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[Xen-changelog] [xen-unstable] [IA64] import perfmon, oprofile related files from linux to linux-sparse



# HG changeset patch
# User awilliam@xxxxxxxxxxx
# Node ID da51aee40456f617666586154b46874480cea768
# Parent  6cfe32a69ac62a1eeea1f1a9782ea4cd62fdd80d
[IA64] import perfmon, oprofile related files from linux to linux-sparse

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

Updated to 2.6.16.33

Signed-off-by: Alex Williamson <alex.williamson@xxxxxx>
---
 linux-2.6-xen-sparse/arch/ia64/kernel/perfmon.c   | 6852 ++++++++++++++++++++++
 linux-2.6-xen-sparse/arch/ia64/oprofile/Makefile  |   10 
 linux-2.6-xen-sparse/arch/ia64/oprofile/init.c    |   38 
 linux-2.6-xen-sparse/arch/ia64/oprofile/perfmon.c |  100 
 4 files changed, 7000 insertions(+)

diff -r 6cfe32a69ac6 -r da51aee40456 
linux-2.6-xen-sparse/arch/ia64/kernel/perfmon.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/linux-2.6-xen-sparse/arch/ia64/kernel/perfmon.c   Tue Nov 28 11:19:40 
2006 -0700
@@ -0,0 +1,6852 @@
+/*
+ * This file implements the perfmon-2 subsystem which is used
+ * to program the IA-64 Performance Monitoring Unit (PMU).
+ *
+ * The initial version of perfmon.c was written by
+ * Ganesh Venkitachalam, IBM Corp.
+ *
+ * Then it was modified for perfmon-1.x by Stephane Eranian and
+ * David Mosberger, Hewlett Packard Co.
+ *
+ * Version Perfmon-2.x is a rewrite of perfmon-1.x
+ * by Stephane Eranian, Hewlett Packard Co.
+ *
+ * Copyright (C) 1999-2005  Hewlett Packard Co
+ *               Stephane Eranian <eranian@xxxxxxxxxx>
+ *               David Mosberger-Tang <davidm@xxxxxxxxxx>
+ *
+ * More information about perfmon available at:
+ *     http://www.hpl.hp.com/research/linux/perfmon
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/smp_lock.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/sysctl.h>
+#include <linux/list.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/vfs.h>
+#include <linux/pagemap.h>
+#include <linux/mount.h>
+#include <linux/bitops.h>
+#include <linux/capability.h>
+#include <linux/rcupdate.h>
+#include <linux/completion.h>
+
+#include <asm/errno.h>
+#include <asm/intrinsics.h>
+#include <asm/page.h>
+#include <asm/perfmon.h>
+#include <asm/processor.h>
+#include <asm/signal.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/delay.h>
+
+#ifdef CONFIG_PERFMON
+/*
+ * perfmon context state
+ */
+#define PFM_CTX_UNLOADED       1       /* context is not loaded onto any task 
*/
+#define PFM_CTX_LOADED         2       /* context is loaded onto a task */
+#define PFM_CTX_MASKED         3       /* context is loaded but monitoring is 
masked due to overflow */
+#define PFM_CTX_ZOMBIE         4       /* owner of the context is closing it */
+
+#define PFM_INVALID_ACTIVATION (~0UL)
+
+/*
+ * depth of message queue
+ */
+#define PFM_MAX_MSGS           32
+#define PFM_CTXQ_EMPTY(g)      ((g)->ctx_msgq_head == (g)->ctx_msgq_tail)
+
+/*
+ * type of a PMU register (bitmask).
+ * bitmask structure:
+ *     bit0   : register implemented
+ *     bit1   : end marker
+ *     bit2-3 : reserved
+ *     bit4   : pmc has pmc.pm
+ *     bit5   : pmc controls a counter (has pmc.oi), pmd is used as counter
+ *     bit6-7 : register type
+ *     bit8-31: reserved
+ */
+#define PFM_REG_NOTIMPL                0x0 /* not implemented at all */
+#define PFM_REG_IMPL           0x1 /* register implemented */
+#define PFM_REG_END            0x2 /* end marker */
+#define PFM_REG_MONITOR                (0x1<<4|PFM_REG_IMPL) /* a PMC with a 
pmc.pm field only */
+#define PFM_REG_COUNTING       (0x2<<4|PFM_REG_MONITOR) /* a monitor + pmc.oi+ 
PMD used as a counter */
+#define PFM_REG_CONTROL                (0x4<<4|PFM_REG_IMPL) /* PMU control 
register */
+#define        PFM_REG_CONFIG          (0x8<<4|PFM_REG_IMPL) /* configuration 
register */
+#define PFM_REG_BUFFER         (0xc<<4|PFM_REG_IMPL) /* PMD used as buffer */
+
+#define PMC_IS_LAST(i) (pmu_conf->pmc_desc[i].type & PFM_REG_END)
+#define PMD_IS_LAST(i) (pmu_conf->pmd_desc[i].type & PFM_REG_END)
+
+#define PMC_OVFL_NOTIFY(ctx, i)        ((ctx)->ctx_pmds[i].flags &  
PFM_REGFL_OVFL_NOTIFY)
+
+/* i assumed unsigned */
+#define PMC_IS_IMPL(i)   (i< PMU_MAX_PMCS && (pmu_conf->pmc_desc[i].type & 
PFM_REG_IMPL))
+#define PMD_IS_IMPL(i)   (i< PMU_MAX_PMDS && (pmu_conf->pmd_desc[i].type & 
PFM_REG_IMPL))
+
+/* XXX: these assume that register i is implemented */
+#define PMD_IS_COUNTING(i) ((pmu_conf->pmd_desc[i].type & PFM_REG_COUNTING) == 
PFM_REG_COUNTING)
+#define PMC_IS_COUNTING(i) ((pmu_conf->pmc_desc[i].type & PFM_REG_COUNTING) == 
PFM_REG_COUNTING)
+#define PMC_IS_MONITOR(i)  ((pmu_conf->pmc_desc[i].type & PFM_REG_MONITOR)  == 
PFM_REG_MONITOR)
+#define PMC_IS_CONTROL(i)  ((pmu_conf->pmc_desc[i].type & PFM_REG_CONTROL)  == 
PFM_REG_CONTROL)
+
+#define PMC_DFL_VAL(i)     pmu_conf->pmc_desc[i].default_value
+#define PMC_RSVD_MASK(i)   pmu_conf->pmc_desc[i].reserved_mask
+#define PMD_PMD_DEP(i)    pmu_conf->pmd_desc[i].dep_pmd[0]
+#define PMC_PMD_DEP(i)    pmu_conf->pmc_desc[i].dep_pmd[0]
+
+#define PFM_NUM_IBRS     IA64_NUM_DBG_REGS
+#define PFM_NUM_DBRS     IA64_NUM_DBG_REGS
+
+#define CTX_OVFL_NOBLOCK(c)    ((c)->ctx_fl_block == 0)
+#define CTX_HAS_SMPL(c)                ((c)->ctx_fl_is_sampling)
+#define PFM_CTX_TASK(h)                (h)->ctx_task
+
+#define PMU_PMC_OI             5 /* position of pmc.oi bit */
+
+/* XXX: does not support more than 64 PMDs */
+#define CTX_USED_PMD(ctx, mask) (ctx)->ctx_used_pmds[0] |= (mask)
+#define CTX_IS_USED_PMD(ctx, c) (((ctx)->ctx_used_pmds[0] & (1UL << (c))) != 
0UL)
+
+#define CTX_USED_MONITOR(ctx, mask) (ctx)->ctx_used_monitors[0] |= (mask)
+
+#define CTX_USED_IBR(ctx,n)    (ctx)->ctx_used_ibrs[(n)>>6] |= 1UL<< ((n) % 64)
+#define CTX_USED_DBR(ctx,n)    (ctx)->ctx_used_dbrs[(n)>>6] |= 1UL<< ((n) % 64)
+#define CTX_USES_DBREGS(ctx)   (((pfm_context_t 
*)(ctx))->ctx_fl_using_dbreg==1)
+#define PFM_CODE_RR    0       /* requesting code range restriction */
+#define PFM_DATA_RR    1       /* requestion data range restriction */
+
+#define PFM_CPUINFO_CLEAR(v)   pfm_get_cpu_var(pfm_syst_info) &= ~(v)
+#define PFM_CPUINFO_SET(v)     pfm_get_cpu_var(pfm_syst_info) |= (v)
+#define PFM_CPUINFO_GET()      pfm_get_cpu_var(pfm_syst_info)
+
+#define RDEP(x)        (1UL<<(x))
+
+/*
+ * context protection macros
+ * in SMP:
+ *     - we need to protect against CPU concurrency (spin_lock)
+ *     - we need to protect against PMU overflow interrupts (local_irq_disable)
+ * in UP:
+ *     - we need to protect against PMU overflow interrupts (local_irq_disable)
+ *
+ * spin_lock_irqsave()/spin_lock_irqrestore():
+ *     in SMP: local_irq_disable + spin_lock
+ *     in UP : local_irq_disable
+ *
+ * spin_lock()/spin_lock():
+ *     in UP : removed automatically
+ *     in SMP: protect against context accesses from other CPU. interrupts
+ *             are not masked. This is useful for the PMU interrupt handler
+ *             because we know we will not get PMU concurrency in that code.
+ */
+#define PROTECT_CTX(c, f) \
+       do {  \
+               DPRINT(("spinlock_irq_save ctx %p by [%d]\n", c, 
current->pid)); \
+               spin_lock_irqsave(&(c)->ctx_lock, f); \
+               DPRINT(("spinlocked ctx %p  by [%d]\n", c, current->pid)); \
+       } while(0)
+
+#define UNPROTECT_CTX(c, f) \
+       do { \
+               DPRINT(("spinlock_irq_restore ctx %p by [%d]\n", c, 
current->pid)); \
+               spin_unlock_irqrestore(&(c)->ctx_lock, f); \
+       } while(0)
+
+#define PROTECT_CTX_NOPRINT(c, f) \
+       do {  \
+               spin_lock_irqsave(&(c)->ctx_lock, f); \
+       } while(0)
+
+
+#define UNPROTECT_CTX_NOPRINT(c, f) \
+       do { \
+               spin_unlock_irqrestore(&(c)->ctx_lock, f); \
+       } while(0)
+
+
+#define PROTECT_CTX_NOIRQ(c) \
+       do {  \
+               spin_lock(&(c)->ctx_lock); \
+       } while(0)
+
+#define UNPROTECT_CTX_NOIRQ(c) \
+       do { \
+               spin_unlock(&(c)->ctx_lock); \
+       } while(0)
+
+
+#ifdef CONFIG_SMP
+
+#define GET_ACTIVATION()       pfm_get_cpu_var(pmu_activation_number)
+#define INC_ACTIVATION()       pfm_get_cpu_var(pmu_activation_number)++
+#define SET_ACTIVATION(c)      (c)->ctx_last_activation = GET_ACTIVATION()
+
+#else /* !CONFIG_SMP */
+#define SET_ACTIVATION(t)      do {} while(0)
+#define GET_ACTIVATION(t)      do {} while(0)
+#define INC_ACTIVATION(t)      do {} while(0)
+#endif /* CONFIG_SMP */
+
+#define SET_PMU_OWNER(t, c)    do { pfm_get_cpu_var(pmu_owner) = (t); 
pfm_get_cpu_var(pmu_ctx) = (c); } while(0)
+#define GET_PMU_OWNER()                pfm_get_cpu_var(pmu_owner)
+#define GET_PMU_CTX()          pfm_get_cpu_var(pmu_ctx)
+
+#define LOCK_PFS(g)            spin_lock_irqsave(&pfm_sessions.pfs_lock, g)
+#define UNLOCK_PFS(g)          spin_unlock_irqrestore(&pfm_sessions.pfs_lock, 
g)
+
+#define PFM_REG_RETFLAG_SET(flags, val)        do { flags &= 
~PFM_REG_RETFL_MASK; flags |= (val); } while(0)
+
+/*
+ * cmp0 must be the value of pmc0
+ */
+#define PMC0_HAS_OVFL(cmp0)  (cmp0 & ~0x1UL)
+
+#define PFMFS_MAGIC 0xa0b4d889
+
+/*
+ * debugging
+ */
+#define PFM_DEBUGGING 1
+#ifdef PFM_DEBUGGING
+#define DPRINT(a) \
+       do { \
+               if (unlikely(pfm_sysctl.debug >0)) { printk("%s.%d: CPU%d [%d] 
", __FUNCTION__, __LINE__, smp_processor_id(), current->pid); printk a; } \
+       } while (0)
+
+#define DPRINT_ovfl(a) \
+       do { \
+               if (unlikely(pfm_sysctl.debug > 0 && pfm_sysctl.debug_ovfl >0)) 
{ printk("%s.%d: CPU%d [%d] ", __FUNCTION__, __LINE__, smp_processor_id(), 
current->pid); printk a; } \
+       } while (0)
+#endif
+
+/*
+ * 64-bit software counter structure
+ *
+ * the next_reset_type is applied to the next call to pfm_reset_regs()
+ */
+typedef struct {
+       unsigned long   val;            /* virtual 64bit counter value */
+       unsigned long   lval;           /* last reset value */
+       unsigned long   long_reset;     /* reset value on sampling overflow */
+       unsigned long   short_reset;    /* reset value on overflow */
+       unsigned long   reset_pmds[4];  /* which other pmds to reset when this 
counter overflows */
+       unsigned long   smpl_pmds[4];   /* which pmds are accessed when counter 
overflow */
+       unsigned long   seed;           /* seed for random-number generator */
+       unsigned long   mask;           /* mask for random-number generator */
+       unsigned int    flags;          /* notify/do not notify */
+       unsigned long   eventid;        /* overflow event identifier */
+} pfm_counter_t;
+
+/*
+ * context flags
+ */
+typedef struct {
+       unsigned int block:1;           /* when 1, task will blocked on user 
notifications */
+       unsigned int system:1;          /* do system wide monitoring */
+       unsigned int using_dbreg:1;     /* using range restrictions (debug 
registers) */
+       unsigned int is_sampling:1;     /* true if using a custom format */
+       unsigned int excl_idle:1;       /* exclude idle task in system wide 
session */
+       unsigned int going_zombie:1;    /* context is zombie (MASKED+blocking) 
*/
+       unsigned int trap_reason:2;     /* reason for going into 
pfm_handle_work() */
+       unsigned int no_msg:1;          /* no message sent on overflow */
+       unsigned int can_restart:1;     /* allowed to issue a PFM_RESTART */
+       unsigned int reserved:22;
+} pfm_context_flags_t;
+
+#define PFM_TRAP_REASON_NONE           0x0     /* default value */
+#define PFM_TRAP_REASON_BLOCK          0x1     /* we need to block on overflow 
*/
+#define PFM_TRAP_REASON_RESET          0x2     /* we need to reset PMDs */
+
+
+/*
+ * perfmon context: encapsulates all the state of a monitoring session
+ */
+
+typedef struct pfm_context {
+       spinlock_t              ctx_lock;               /* context protection */
+
+       pfm_context_flags_t     ctx_flags;              /* bitmask of flags  
(block reason incl.) */
+       unsigned int            ctx_state;              /* state: 
active/inactive (no bitfield) */
+
+       struct task_struct      *ctx_task;              /* task to which 
context is attached */
+
+       unsigned long           ctx_ovfl_regs[4];       /* which registers 
overflowed (notification) */
+
+       struct completion       ctx_restart_done;       /* use for blocking 
notification mode */
+
+       unsigned long           ctx_used_pmds[4];       /* bitmask of PMD used  
          */
+       unsigned long           ctx_all_pmds[4];        /* bitmask of all 
accessible PMDs */
+       unsigned long           ctx_reload_pmds[4];     /* bitmask of force 
reload PMD on ctxsw in */
+
+       unsigned long           ctx_all_pmcs[4];        /* bitmask of all 
accessible PMCs */
+       unsigned long           ctx_reload_pmcs[4];     /* bitmask of force 
reload PMC on ctxsw in */
+       unsigned long           ctx_used_monitors[4];   /* bitmask of monitor 
PMC being used */
+
+       unsigned long           ctx_pmcs[IA64_NUM_PMC_REGS];    /*  saved 
copies of PMC values */
+
+       unsigned int            ctx_used_ibrs[1];               /* bitmask of 
used IBR (speedup ctxsw in) */
+       unsigned int            ctx_used_dbrs[1];               /* bitmask of 
used DBR (speedup ctxsw in) */
+       unsigned long           ctx_dbrs[IA64_NUM_DBG_REGS];    /* DBR values 
(cache) when not loaded */
+       unsigned long           ctx_ibrs[IA64_NUM_DBG_REGS];    /* IBR values 
(cache) when not loaded */
+
+       pfm_counter_t           ctx_pmds[IA64_NUM_PMD_REGS]; /* software state 
for PMDS */
+
+       u64                     ctx_saved_psr_up;       /* only contains psr.up 
value */
+
+       unsigned long           ctx_last_activation;    /* context last 
activation number for last_cpu */
+       unsigned int            ctx_last_cpu;           /* CPU id of current or 
last CPU used (SMP only) */
+       unsigned int            ctx_cpu;                /* cpu to which perfmon 
is applied (system wide) */
+
+       int                     ctx_fd;                 /* file descriptor used 
my this context */
+       pfm_ovfl_arg_t          ctx_ovfl_arg;           /* argument to custom 
buffer format handler */
+
+       pfm_buffer_fmt_t        *ctx_buf_fmt;           /* buffer format 
callbacks */
+       void                    *ctx_smpl_hdr;          /* points to sampling 
buffer header kernel vaddr */
+       unsigned long           ctx_smpl_size;          /* size of sampling 
buffer */
+       void                    *ctx_smpl_vaddr;        /* user level virtual 
address of smpl buffer */
+
+       wait_queue_head_t       ctx_msgq_wait;
+       pfm_msg_t               ctx_msgq[PFM_MAX_MSGS];
+       int                     ctx_msgq_head;
+       int                     ctx_msgq_tail;
+       struct fasync_struct    *ctx_async_queue;
+
+       wait_queue_head_t       ctx_zombieq;            /* termination cleanup 
wait queue */
+} pfm_context_t;
+
+/*
+ * magic number used to verify that structure is really
+ * a perfmon context
+ */
+#define PFM_IS_FILE(f)         ((f)->f_op == &pfm_file_ops)
+
+#define PFM_GET_CTX(t)         ((pfm_context_t *)(t)->thread.pfm_context)
+
+#ifdef CONFIG_SMP
+#define SET_LAST_CPU(ctx, v)   (ctx)->ctx_last_cpu = (v)
+#define GET_LAST_CPU(ctx)      (ctx)->ctx_last_cpu
+#else
+#define SET_LAST_CPU(ctx, v)   do {} while(0)
+#define GET_LAST_CPU(ctx)      do {} while(0)
+#endif
+
+
+#define ctx_fl_block           ctx_flags.block
+#define ctx_fl_system          ctx_flags.system
+#define ctx_fl_using_dbreg     ctx_flags.using_dbreg
+#define ctx_fl_is_sampling     ctx_flags.is_sampling
+#define ctx_fl_excl_idle       ctx_flags.excl_idle
+#define ctx_fl_going_zombie    ctx_flags.going_zombie
+#define ctx_fl_trap_reason     ctx_flags.trap_reason
+#define ctx_fl_no_msg          ctx_flags.no_msg
+#define ctx_fl_can_restart     ctx_flags.can_restart
+
+#define PFM_SET_WORK_PENDING(t, v)     do { (t)->thread.pfm_needs_checking = 
v; } while(0);
+#define PFM_GET_WORK_PENDING(t)                (t)->thread.pfm_needs_checking
+
+/*
+ * global information about all sessions
+ * mostly used to synchronize between system wide and per-process
+ */
+typedef struct {
+       spinlock_t              pfs_lock;                  /* lock the 
structure */
+
+       unsigned int            pfs_task_sessions;         /* number of per 
task sessions */
+       unsigned int            pfs_sys_sessions;          /* number of per 
system wide sessions */
+       unsigned int            pfs_sys_use_dbregs;        /* incremented when 
a system wide session uses debug regs */
+       unsigned int            pfs_ptrace_use_dbregs;     /* incremented when 
a process uses debug regs */
+       struct task_struct      *pfs_sys_session[NR_CPUS]; /* point to task 
owning a system-wide session */
+} pfm_session_t;
+
+/*
+ * information about a PMC or PMD.
+ * dep_pmd[]: a bitmask of dependent PMD registers
+ * dep_pmc[]: a bitmask of dependent PMC registers
+ */
+typedef int (*pfm_reg_check_t)(struct task_struct *task, pfm_context_t *ctx, 
unsigned int cnum, unsigned long *val, struct pt_regs *regs);
+typedef struct {
+       unsigned int            type;
+       int                     pm_pos;
+       unsigned long           default_value;  /* power-on default value */
+       unsigned long           reserved_mask;  /* bitmask of reserved bits */
+       pfm_reg_check_t         read_check;
+       pfm_reg_check_t         write_check;
+       unsigned long           dep_pmd[4];
+       unsigned long           dep_pmc[4];
+} pfm_reg_desc_t;
+
+/* assume cnum is a valid monitor */
+#define PMC_PM(cnum, val)      (((val) >> (pmu_conf->pmc_desc[cnum].pm_pos)) & 
0x1)
+
+/*
+ * This structure is initialized at boot time and contains
+ * a description of the PMU main characteristics.
+ *
+ * If the probe function is defined, detection is based
+ * on its return value: 
+ *     - 0 means recognized PMU
+ *     - anything else means not supported
+ * When the probe function is not defined, then the pmu_family field
+ * is used and it must match the host CPU family such that:
+ *     - cpu->family & config->pmu_family != 0
+ */
+typedef struct {
+       unsigned long  ovfl_val;        /* overflow value for counters */
+
+       pfm_reg_desc_t *pmc_desc;       /* detailed PMC register dependencies 
descriptions */
+       pfm_reg_desc_t *pmd_desc;       /* detailed PMD register dependencies 
descriptions */
+
+       unsigned int   num_pmcs;        /* number of PMCS: computed at init 
time */
+       unsigned int   num_pmds;        /* number of PMDS: computed at init 
time */
+       unsigned long  impl_pmcs[4];    /* bitmask of implemented PMCS */
+       unsigned long  impl_pmds[4];    /* bitmask of implemented PMDS */
+
+       char          *pmu_name;        /* PMU family name */
+       unsigned int  pmu_family;       /* cpuid family pattern used to 
identify pmu */
+       unsigned int  flags;            /* pmu specific flags */
+       unsigned int  num_ibrs;         /* number of IBRS: computed at init 
time */
+       unsigned int  num_dbrs;         /* number of DBRS: computed at init 
time */
+       unsigned int  num_counters;     /* PMC/PMD counting pairs : computed at 
init time */
+       int           (*probe)(void);   /* customized probe routine */
+       unsigned int  use_rr_dbregs:1;  /* set if debug registers used for 
range restriction */
+} pmu_config_t;
+/*
+ * PMU specific flags
+ */
+#define PFM_PMU_IRQ_RESEND     1       /* PMU needs explicit IRQ resend */
+
+/*
+ * debug register related type definitions
+ */
+typedef struct {
+       unsigned long ibr_mask:56;
+       unsigned long ibr_plm:4;
+       unsigned long ibr_ig:3;
+       unsigned long ibr_x:1;
+} ibr_mask_reg_t;
+
+typedef struct {
+       unsigned long dbr_mask:56;
+       unsigned long dbr_plm:4;
+       unsigned long dbr_ig:2;
+       unsigned long dbr_w:1;
+       unsigned long dbr_r:1;
+} dbr_mask_reg_t;
+
+typedef union {
+       unsigned long  val;
+       ibr_mask_reg_t ibr;
+       dbr_mask_reg_t dbr;
+} dbreg_t;
+
+
+/*
+ * perfmon command descriptions
+ */
+typedef struct {
+       int             (*cmd_func)(pfm_context_t *ctx, void *arg, int count, 
struct pt_regs *regs);
+       char            *cmd_name;
+       int             cmd_flags;
+       unsigned int    cmd_narg;
+       size_t          cmd_argsize;
+       int             (*cmd_getsize)(void *arg, size_t *sz);
+} pfm_cmd_desc_t;
+
+#define PFM_CMD_FD             0x01    /* command requires a file descriptor */
+#define PFM_CMD_ARG_READ       0x02    /* command must read argument(s) */
+#define PFM_CMD_ARG_RW         0x04    /* command must read/write argument(s) 
*/
+#define PFM_CMD_STOP           0x08    /* command does not work on zombie 
context */
+
+
+#define PFM_CMD_NAME(cmd)      pfm_cmd_tab[(cmd)].cmd_name
+#define PFM_CMD_READ_ARG(cmd)  (pfm_cmd_tab[(cmd)].cmd_flags & 
PFM_CMD_ARG_READ)
+#define PFM_CMD_RW_ARG(cmd)    (pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_ARG_RW)
+#define PFM_CMD_USE_FD(cmd)    (pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_FD)
+#define PFM_CMD_STOPPED(cmd)   (pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_STOP)
+
+#define PFM_CMD_ARG_MANY       -1 /* cannot be zero */
+
+typedef struct {
+       unsigned long pfm_spurious_ovfl_intr_count;     /* keep track of 
spurious ovfl interrupts */
+       unsigned long pfm_replay_ovfl_intr_count;       /* keep track of 
replayed ovfl interrupts */
+       unsigned long pfm_ovfl_intr_count;              /* keep track of ovfl 
interrupts */
+       unsigned long pfm_ovfl_intr_cycles;             /* cycles spent 
processing ovfl interrupts */
+       unsigned long pfm_ovfl_intr_cycles_min;         /* min cycles spent 
processing ovfl interrupts */
+       unsigned long pfm_ovfl_intr_cycles_max;         /* max cycles spent 
processing ovfl interrupts */
+       unsigned long pfm_smpl_handler_calls;
+       unsigned long pfm_smpl_handler_cycles;
+       char pad[SMP_CACHE_BYTES] ____cacheline_aligned;
+} pfm_stats_t;
+
+/*
+ * perfmon internal variables
+ */
+static pfm_stats_t             pfm_stats[NR_CPUS];
+static pfm_session_t           pfm_sessions;   /* global sessions information 
*/
+
+static DEFINE_SPINLOCK(pfm_alt_install_check);
+static pfm_intr_handler_desc_t  *pfm_alt_intr_handler;
+
+static struct proc_dir_entry   *perfmon_dir;
+static pfm_uuid_t              pfm_null_uuid = {0,};
+
+static spinlock_t              pfm_buffer_fmt_lock;
+static LIST_HEAD(pfm_buffer_fmt_list);
+
+static pmu_config_t            *pmu_conf;
+
+/* sysctl() controls */
+pfm_sysctl_t pfm_sysctl;
+EXPORT_SYMBOL(pfm_sysctl);
+
+static ctl_table pfm_ctl_table[]={
+       {1, "debug", &pfm_sysctl.debug, sizeof(int), 0666, NULL, 
&proc_dointvec, NULL,},
+       {2, "debug_ovfl", &pfm_sysctl.debug_ovfl, sizeof(int), 0666, NULL, 
&proc_dointvec, NULL,},
+       {3, "fastctxsw", &pfm_sysctl.fastctxsw, sizeof(int), 0600, NULL, 
&proc_dointvec, NULL,},
+       {4, "expert_mode", &pfm_sysctl.expert_mode, sizeof(int), 0600, NULL, 
&proc_dointvec, NULL,},
+       { 0, },
+};
+static ctl_table pfm_sysctl_dir[] = {
+       {1, "perfmon", NULL, 0, 0755, pfm_ctl_table, },
+       {0,},
+};
+static ctl_table pfm_sysctl_root[] = {
+       {1, "kernel", NULL, 0, 0755, pfm_sysctl_dir, },
+       {0,},
+};
+static struct ctl_table_header *pfm_sysctl_header;
+
+static int pfm_context_unload(pfm_context_t *ctx, void *arg, int count, struct 
pt_regs *regs);
+static int pfm_flush(struct file *filp);
+
+#define pfm_get_cpu_var(v)             __ia64_per_cpu_var(v)
+#define pfm_get_cpu_data(a,b)          per_cpu(a, b)
+
+static inline void
+pfm_put_task(struct task_struct *task)
+{
+       if (task != current) put_task_struct(task);
+}
+
+static inline void
+pfm_set_task_notify(struct task_struct *task)
+{
+       struct thread_info *info;
+
+       info = (struct thread_info *) ((char *) task + IA64_TASK_SIZE);
+       set_bit(TIF_NOTIFY_RESUME, &info->flags);
+}
+
+static inline void
+pfm_clear_task_notify(void)
+{
+       clear_thread_flag(TIF_NOTIFY_RESUME);
+}
+
+static inline void
+pfm_reserve_page(unsigned long a)
+{
+       SetPageReserved(vmalloc_to_page((void *)a));
+}
+static inline void
+pfm_unreserve_page(unsigned long a)
+{
+       ClearPageReserved(vmalloc_to_page((void*)a));
+}
+
+static inline unsigned long
+pfm_protect_ctx_ctxsw(pfm_context_t *x)
+{
+       spin_lock(&(x)->ctx_lock);
+       return 0UL;
+}
+
+static inline void
+pfm_unprotect_ctx_ctxsw(pfm_context_t *x, unsigned long f)
+{
+       spin_unlock(&(x)->ctx_lock);
+}
+
+static inline unsigned int
+pfm_do_munmap(struct mm_struct *mm, unsigned long addr, size_t len, int acct)
+{
+       return do_munmap(mm, addr, len);
+}
+
+static inline unsigned long 
+pfm_get_unmapped_area(struct file *file, unsigned long addr, unsigned long 
len, unsigned long pgoff, unsigned long flags, unsigned long exec)
+{
+       return get_unmapped_area(file, addr, len, pgoff, flags);
+}
+
+
+static struct super_block *
+pfmfs_get_sb(struct file_system_type *fs_type, int flags, const char 
*dev_name, void *data)
+{
+       return get_sb_pseudo(fs_type, "pfm:", NULL, PFMFS_MAGIC);
+}
+
+static struct file_system_type pfm_fs_type = {
+       .name     = "pfmfs",
+       .get_sb   = pfmfs_get_sb,
+       .kill_sb  = kill_anon_super,
+};
+
+DEFINE_PER_CPU(unsigned long, pfm_syst_info);
+DEFINE_PER_CPU(struct task_struct *, pmu_owner);
+DEFINE_PER_CPU(pfm_context_t  *, pmu_ctx);
+DEFINE_PER_CPU(unsigned long, pmu_activation_number);
+EXPORT_PER_CPU_SYMBOL_GPL(pfm_syst_info);
+
+
+/* forward declaration */
+static struct file_operations pfm_file_ops;
+
+/*
+ * forward declarations
+ */
+#ifndef CONFIG_SMP
+static void pfm_lazy_save_regs (struct task_struct *ta);
+#endif
+
+void dump_pmu_state(const char *);
+static int pfm_write_ibr_dbr(int mode, pfm_context_t *ctx, void *arg, int 
count, struct pt_regs *regs);
+
+#include "perfmon_itanium.h"
+#include "perfmon_mckinley.h"
+#include "perfmon_montecito.h"
+#include "perfmon_generic.h"
+
+static pmu_config_t *pmu_confs[]={
+       &pmu_conf_mont,
+       &pmu_conf_mck,
+       &pmu_conf_ita,
+       &pmu_conf_gen, /* must be last */
+       NULL
+};
+
+
+static int pfm_end_notify_user(pfm_context_t *ctx);
+
+static inline void
+pfm_clear_psr_pp(void)
+{
+       ia64_rsm(IA64_PSR_PP);
+       ia64_srlz_i();
+}
+
+static inline void
+pfm_set_psr_pp(void)
+{
+       ia64_ssm(IA64_PSR_PP);
+       ia64_srlz_i();
+}
+
+static inline void
+pfm_clear_psr_up(void)
+{
+       ia64_rsm(IA64_PSR_UP);
+       ia64_srlz_i();
+}
+
+static inline void
+pfm_set_psr_up(void)
+{
+       ia64_ssm(IA64_PSR_UP);
+       ia64_srlz_i();
+}
+
+static inline unsigned long
+pfm_get_psr(void)
+{
+       unsigned long tmp;
+       tmp = ia64_getreg(_IA64_REG_PSR);
+       ia64_srlz_i();
+       return tmp;
+}
+
+static inline void
+pfm_set_psr_l(unsigned long val)
+{
+       ia64_setreg(_IA64_REG_PSR_L, val);
+       ia64_srlz_i();
+}
+
+static inline void
+pfm_freeze_pmu(void)
+{
+       ia64_set_pmc(0,1UL);
+       ia64_srlz_d();
+}
+
+static inline void
+pfm_unfreeze_pmu(void)
+{
+       ia64_set_pmc(0,0UL);
+       ia64_srlz_d();
+}
+
+static inline void
+pfm_restore_ibrs(unsigned long *ibrs, unsigned int nibrs)
+{
+       int i;
+
+       for (i=0; i < nibrs; i++) {
+               ia64_set_ibr(i, ibrs[i]);
+               ia64_dv_serialize_instruction();
+       }
+       ia64_srlz_i();
+}
+
+static inline void
+pfm_restore_dbrs(unsigned long *dbrs, unsigned int ndbrs)
+{
+       int i;
+
+       for (i=0; i < ndbrs; i++) {
+               ia64_set_dbr(i, dbrs[i]);
+               ia64_dv_serialize_data();
+       }
+       ia64_srlz_d();
+}
+
+/*
+ * PMD[i] must be a counter. no check is made
+ */
+static inline unsigned long
+pfm_read_soft_counter(pfm_context_t *ctx, int i)
+{
+       return ctx->ctx_pmds[i].val + (ia64_get_pmd(i) & pmu_conf->ovfl_val);
+}
+
+/*
+ * PMD[i] must be a counter. no check is made
+ */
+static inline void
+pfm_write_soft_counter(pfm_context_t *ctx, int i, unsigned long val)
+{
+       unsigned long ovfl_val = pmu_conf->ovfl_val;
+
+       ctx->ctx_pmds[i].val = val  & ~ovfl_val;
+       /*
+        * writing to unimplemented part is ignore, so we do not need to
+        * mask off top part
+        */
+       ia64_set_pmd(i, val & ovfl_val);
+}
+
+static pfm_msg_t *
+pfm_get_new_msg(pfm_context_t *ctx)
+{
+       int idx, next;
+
+       next = (ctx->ctx_msgq_tail+1) % PFM_MAX_MSGS;
+
+       DPRINT(("ctx_fd=%p head=%d tail=%d\n", ctx, ctx->ctx_msgq_head, 
ctx->ctx_msgq_tail));
+       if (next == ctx->ctx_msgq_head) return NULL;
+
+       idx =   ctx->ctx_msgq_tail;
+       ctx->ctx_msgq_tail = next;
+
+       DPRINT(("ctx=%p head=%d tail=%d msg=%d\n", ctx, ctx->ctx_msgq_head, 
ctx->ctx_msgq_tail, idx));
+
+       return ctx->ctx_msgq+idx;
+}
+
+static pfm_msg_t *
+pfm_get_next_msg(pfm_context_t *ctx)
+{
+       pfm_msg_t *msg;
+
+       DPRINT(("ctx=%p head=%d tail=%d\n", ctx, ctx->ctx_msgq_head, 
ctx->ctx_msgq_tail));
+
+       if (PFM_CTXQ_EMPTY(ctx)) return NULL;
+
+       /*
+        * get oldest message
+        */
+       msg = ctx->ctx_msgq+ctx->ctx_msgq_head;
+
+       /*
+        * and move forward
+        */
+       ctx->ctx_msgq_head = (ctx->ctx_msgq_head+1) % PFM_MAX_MSGS;
+
+       DPRINT(("ctx=%p head=%d tail=%d type=%d\n", ctx, ctx->ctx_msgq_head, 
ctx->ctx_msgq_tail, msg->pfm_gen_msg.msg_type));
+
+       return msg;
+}
+
+static void
+pfm_reset_msgq(pfm_context_t *ctx)
+{
+       ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0;
+       DPRINT(("ctx=%p msgq reset\n", ctx));
+}
+
+static void *
+pfm_rvmalloc(unsigned long size)
+{
+       void *mem;
+       unsigned long addr;
+
+       size = PAGE_ALIGN(size);
+       mem  = vmalloc(size);
+       if (mem) {
+               //printk("perfmon: CPU%d pfm_rvmalloc(%ld)=%p\n", 
smp_processor_id(), size, mem);
+               memset(mem, 0, size);
+               addr = (unsigned long)mem;
+               while (size > 0) {
+                       pfm_reserve_page(addr);
+                       addr+=PAGE_SIZE;
+                       size-=PAGE_SIZE;
+               }
+       }
+       return mem;
+}
+
+static void
+pfm_rvfree(void *mem, unsigned long size)
+{
+       unsigned long addr;
+
+       if (mem) {
+               DPRINT(("freeing physical buffer @%p size=%lu\n", mem, size));
+               addr = (unsigned long) mem;
+               while ((long) size > 0) {
+                       pfm_unreserve_page(addr);
+                       addr+=PAGE_SIZE;
+                       size-=PAGE_SIZE;
+               }
+               vfree(mem);
+       }
+       return;
+}
+
+static pfm_context_t *
+pfm_context_alloc(void)
+{
+       pfm_context_t *ctx;
+
+       /* 
+        * allocate context descriptor 
+        * must be able to free with interrupts disabled
+        */
+       ctx = kmalloc(sizeof(pfm_context_t), GFP_KERNEL);
+       if (ctx) {
+               memset(ctx, 0, sizeof(pfm_context_t));
+               DPRINT(("alloc ctx @%p\n", ctx));
+       }
+       return ctx;
+}
+
+static void
+pfm_context_free(pfm_context_t *ctx)
+{
+       if (ctx) {
+               DPRINT(("free ctx @%p\n", ctx));
+               kfree(ctx);
+       }
+}
+
+static void
+pfm_mask_monitoring(struct task_struct *task)
+{
+       pfm_context_t *ctx = PFM_GET_CTX(task);
+       struct thread_struct *th = &task->thread;
+       unsigned long mask, val, ovfl_mask;
+       int i;
+
+       DPRINT_ovfl(("masking monitoring for [%d]\n", task->pid));
+
+       ovfl_mask = pmu_conf->ovfl_val;
+       /*
+        * monitoring can only be masked as a result of a valid
+        * counter overflow. In UP, it means that the PMU still
+        * has an owner. Note that the owner can be different
+        * from the current task. However the PMU state belongs
+        * to the owner.
+        * In SMP, a valid overflow only happens when task is
+        * current. Therefore if we come here, we know that
+        * the PMU state belongs to the current task, therefore
+        * we can access the live registers.
+        *
+        * So in both cases, the live register contains the owner's
+        * state. We can ONLY touch the PMU registers and NOT the PSR.
+        *
+        * As a consequence to this call, the thread->pmds[] array
+        * contains stale information which must be ignored
+        * when context is reloaded AND monitoring is active (see
+        * pfm_restart).
+        */
+       mask = ctx->ctx_used_pmds[0];
+       for (i = 0; mask; i++, mask>>=1) {
+               /* skip non used pmds */
+               if ((mask & 0x1) == 0) continue;
+               val = ia64_get_pmd(i);
+
+               if (PMD_IS_COUNTING(i)) {
+                       /*
+                        * we rebuild the full 64 bit value of the counter
+                        */
+                       ctx->ctx_pmds[i].val += (val & ovfl_mask);
+               } else {
+                       ctx->ctx_pmds[i].val = val;
+               }
+               DPRINT_ovfl(("pmd[%d]=0x%lx hw_pmd=0x%lx\n",
+                       i,
+                       ctx->ctx_pmds[i].val,
+                       val & ovfl_mask));
+       }
+       /*
+        * mask monitoring by setting the privilege level to 0
+        * we cannot use psr.pp/psr.up for this, it is controlled by
+        * the user
+        *
+        * if task is current, modify actual registers, otherwise modify
+        * thread save state, i.e., what will be restored in pfm_load_regs()
+        */
+       mask = ctx->ctx_used_monitors[0] >> PMU_FIRST_COUNTER;
+       for(i= PMU_FIRST_COUNTER; mask; i++, mask>>=1) {
+               if ((mask & 0x1) == 0UL) continue;
+               ia64_set_pmc(i, th->pmcs[i] & ~0xfUL);
+               th->pmcs[i] &= ~0xfUL;
+               DPRINT_ovfl(("pmc[%d]=0x%lx\n", i, th->pmcs[i]));
+       }
+       /*
+        * make all of this visible
+        */
+       ia64_srlz_d();
+}
+
+/*
+ * must always be done with task == current
+ *
+ * context must be in MASKED state when calling
+ */
+static void
+pfm_restore_monitoring(struct task_struct *task)
+{
+       pfm_context_t *ctx = PFM_GET_CTX(task);
+       struct thread_struct *th = &task->thread;
+       unsigned long mask, ovfl_mask;
+       unsigned long psr, val;
+       int i, is_system;
+
+       is_system = ctx->ctx_fl_system;
+       ovfl_mask = pmu_conf->ovfl_val;
+
+       if (task != current) {
+               printk(KERN_ERR "perfmon.%d: invalid task[%d] current[%d]\n", 
__LINE__, task->pid, current->pid);
+               return;
+       }
+       if (ctx->ctx_state != PFM_CTX_MASKED) {
+               printk(KERN_ERR "perfmon.%d: task[%d] current[%d] invalid 
state=%d\n", __LINE__,
+                       task->pid, current->pid, ctx->ctx_state);
+               return;
+       }
+       psr = pfm_get_psr();
+       /*
+        * monitoring is masked via the PMC.
+        * As we restore their value, we do not want each counter to
+        * restart right away. We stop monitoring using the PSR,
+        * restore the PMC (and PMD) and then re-establish the psr
+        * as it was. Note that there can be no pending overflow at
+        * this point, because monitoring was MASKED.
+        *
+        * system-wide session are pinned and self-monitoring
+        */
+       if (is_system && (PFM_CPUINFO_GET() & PFM_CPUINFO_DCR_PP)) {
+               /* disable dcr pp */
+               ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) & 
~IA64_DCR_PP);
+               pfm_clear_psr_pp();
+       } else {
+               pfm_clear_psr_up();
+       }
+       /*
+        * first, we restore the PMD
+        */
+       mask = ctx->ctx_used_pmds[0];
+       for (i = 0; mask; i++, mask>>=1) {
+               /* skip non used pmds */
+               if ((mask & 0x1) == 0) continue;
+
+               if (PMD_IS_COUNTING(i)) {
+                       /*
+                        * we split the 64bit value according to
+                        * counter width
+                        */
+                       val = ctx->ctx_pmds[i].val & ovfl_mask;
+                       ctx->ctx_pmds[i].val &= ~ovfl_mask;
+               } else {
+                       val = ctx->ctx_pmds[i].val;
+               }
+               ia64_set_pmd(i, val);
+
+               DPRINT(("pmd[%d]=0x%lx hw_pmd=0x%lx\n",
+                       i,
+                       ctx->ctx_pmds[i].val,
+                       val));
+       }
+       /*
+        * restore the PMCs
+        */
+       mask = ctx->ctx_used_monitors[0] >> PMU_FIRST_COUNTER;
+       for(i= PMU_FIRST_COUNTER; mask; i++, mask>>=1) {
+               if ((mask & 0x1) == 0UL) continue;
+               th->pmcs[i] = ctx->ctx_pmcs[i];
+               ia64_set_pmc(i, th->pmcs[i]);
+               DPRINT(("[%d] pmc[%d]=0x%lx\n", task->pid, i, th->pmcs[i]));
+       }
+       ia64_srlz_d();
+
+       /*
+        * must restore DBR/IBR because could be modified while masked
+        * XXX: need to optimize 
+        */
+       if (ctx->ctx_fl_using_dbreg) {
+               pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
+               pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
+       }
+
+       /*
+        * now restore PSR
+        */
+       if (is_system && (PFM_CPUINFO_GET() & PFM_CPUINFO_DCR_PP)) {
+               /* enable dcr pp */
+               ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) | 
IA64_DCR_PP);
+               ia64_srlz_i();
+       }
+       pfm_set_psr_l(psr);
+}
+
+static inline void
+pfm_save_pmds(unsigned long *pmds, unsigned long mask)
+{
+       int i;
+
+       ia64_srlz_d();
+
+       for (i=0; mask; i++, mask>>=1) {
+               if (mask & 0x1) pmds[i] = ia64_get_pmd(i);
+       }
+}
+
+/*
+ * reload from thread state (used for ctxw only)
+ */
+static inline void
+pfm_restore_pmds(unsigned long *pmds, unsigned long mask)
+{
+       int i;
+       unsigned long val, ovfl_val = pmu_conf->ovfl_val;
+
+       for (i=0; mask; i++, mask>>=1) {
+               if ((mask & 0x1) == 0) continue;
+               val = PMD_IS_COUNTING(i) ? pmds[i] & ovfl_val : pmds[i];
+               ia64_set_pmd(i, val);
+       }
+       ia64_srlz_d();
+}
+
+/*
+ * propagate PMD from context to thread-state
+ */
+static inline void
+pfm_copy_pmds(struct task_struct *task, pfm_context_t *ctx)
+{
+       struct thread_struct *thread = &task->thread;
+       unsigned long ovfl_val = pmu_conf->ovfl_val;
+       unsigned long mask = ctx->ctx_all_pmds[0];
+       unsigned long val;
+       int i;
+
+       DPRINT(("mask=0x%lx\n", mask));
+
+       for (i=0; mask; i++, mask>>=1) {
+
+               val = ctx->ctx_pmds[i].val;
+
+               /*
+                * We break up the 64 bit value into 2 pieces
+                * the lower bits go to the machine state in the
+                * thread (will be reloaded on ctxsw in).
+                * The upper part stays in the soft-counter.
+                */
+               if (PMD_IS_COUNTING(i)) {
+                       ctx->ctx_pmds[i].val = val & ~ovfl_val;
+                        val &= ovfl_val;
+               }
+               thread->pmds[i] = val;
+
+               DPRINT(("pmd[%d]=0x%lx soft_val=0x%lx\n",
+                       i,
+                       thread->pmds[i],
+                       ctx->ctx_pmds[i].val));
+       }
+}
+
+/*
+ * propagate PMC from context to thread-state
+ */
+static inline void
+pfm_copy_pmcs(struct task_struct *task, pfm_context_t *ctx)
+{
+       struct thread_struct *thread = &task->thread;
+       unsigned long mask = ctx->ctx_all_pmcs[0];
+       int i;
+
+       DPRINT(("mask=0x%lx\n", mask));
+
+       for (i=0; mask; i++, mask>>=1) {
+               /* masking 0 with ovfl_val yields 0 */
+               thread->pmcs[i] = ctx->ctx_pmcs[i];
+               DPRINT(("pmc[%d]=0x%lx\n", i, thread->pmcs[i]));
+       }
+}
+
+
+
+static inline void
+pfm_restore_pmcs(unsigned long *pmcs, unsigned long mask)
+{
+       int i;
+
+       for (i=0; mask; i++, mask>>=1) {
+               if ((mask & 0x1) == 0) continue;
+               ia64_set_pmc(i, pmcs[i]);
+       }
+       ia64_srlz_d();
+}
+
+static inline int
+pfm_uuid_cmp(pfm_uuid_t a, pfm_uuid_t b)
+{
+       return memcmp(a, b, sizeof(pfm_uuid_t));
+}
+
+static inline int
+pfm_buf_fmt_exit(pfm_buffer_fmt_t *fmt, struct task_struct *task, void *buf, 
struct pt_regs *regs)
+{
+       int ret = 0;
+       if (fmt->fmt_exit) ret = (*fmt->fmt_exit)(task, buf, regs);
+       return ret;
+}
+
+static inline int
+pfm_buf_fmt_getsize(pfm_buffer_fmt_t *fmt, struct task_struct *task, unsigned 
int flags, int cpu, void *arg, unsigned long *size)
+{
+       int ret = 0;
+       if (fmt->fmt_getsize) ret = (*fmt->fmt_getsize)(task, flags, cpu, arg, 
size);
+       return ret;
+}
+
+
+static inline int
+pfm_buf_fmt_validate(pfm_buffer_fmt_t *fmt, struct task_struct *task, unsigned 
int flags,
+                    int cpu, void *arg)
+{
+       int ret = 0;
+       if (fmt->fmt_validate) ret = (*fmt->fmt_validate)(task, flags, cpu, 
arg);
+       return ret;
+}
+
+static inline int
+pfm_buf_fmt_init(pfm_buffer_fmt_t *fmt, struct task_struct *task, void *buf, 
unsigned int flags,
+                    int cpu, void *arg)
+{
+       int ret = 0;
+       if (fmt->fmt_init) ret = (*fmt->fmt_init)(task, buf, flags, cpu, arg);
+       return ret;
+}
+
+static inline int
+pfm_buf_fmt_restart(pfm_buffer_fmt_t *fmt, struct task_struct *task, 
pfm_ovfl_ctrl_t *ctrl, void *buf, struct pt_regs *regs)
+{
+       int ret = 0;
+       if (fmt->fmt_restart) ret = (*fmt->fmt_restart)(task, ctrl, buf, regs);
+       return ret;
+}
+
+static inline int
+pfm_buf_fmt_restart_active(pfm_buffer_fmt_t *fmt, struct task_struct *task, 
pfm_ovfl_ctrl_t *ctrl, void *buf, struct pt_regs *regs)
+{
+       int ret = 0;
+       if (fmt->fmt_restart_active) ret = (*fmt->fmt_restart_active)(task, 
ctrl, buf, regs);
+       return ret;
+}
+
+static pfm_buffer_fmt_t *
+__pfm_find_buffer_fmt(pfm_uuid_t uuid)
+{
+       struct list_head * pos;
+       pfm_buffer_fmt_t * entry;
+
+       list_for_each(pos, &pfm_buffer_fmt_list) {
+               entry = list_entry(pos, pfm_buffer_fmt_t, fmt_list);
+               if (pfm_uuid_cmp(uuid, entry->fmt_uuid) == 0)
+                       return entry;
+       }
+       return NULL;
+}
+ 
+/*
+ * find a buffer format based on its uuid
+ */
+static pfm_buffer_fmt_t *
+pfm_find_buffer_fmt(pfm_uuid_t uuid)
+{
+       pfm_buffer_fmt_t * fmt;
+       spin_lock(&pfm_buffer_fmt_lock);
+       fmt = __pfm_find_buffer_fmt(uuid);
+       spin_unlock(&pfm_buffer_fmt_lock);
+       return fmt;
+}
+ 
+int
+pfm_register_buffer_fmt(pfm_buffer_fmt_t *fmt)
+{
+       int ret = 0;
+
+       /* some sanity checks */
+       if (fmt == NULL || fmt->fmt_name == NULL) return -EINVAL;
+
+       /* we need at least a handler */
+       if (fmt->fmt_handler == NULL) return -EINVAL;
+
+       /*
+        * XXX: need check validity of fmt_arg_size
+        */
+
+       spin_lock(&pfm_buffer_fmt_lock);
+
+       if (__pfm_find_buffer_fmt(fmt->fmt_uuid)) {
+               printk(KERN_ERR "perfmon: duplicate sampling format: %s\n", 
fmt->fmt_name);
+               ret = -EBUSY;
+               goto out;
+       } 
+       list_add(&fmt->fmt_list, &pfm_buffer_fmt_list);
+       printk(KERN_INFO "perfmon: added sampling format %s\n", fmt->fmt_name);
+
+out:
+       spin_unlock(&pfm_buffer_fmt_lock);
+       return ret;
+}
+EXPORT_SYMBOL(pfm_register_buffer_fmt);
+
+int
+pfm_unregister_buffer_fmt(pfm_uuid_t uuid)
+{
+       pfm_buffer_fmt_t *fmt;
+       int ret = 0;
+
+       spin_lock(&pfm_buffer_fmt_lock);
+
+       fmt = __pfm_find_buffer_fmt(uuid);
+       if (!fmt) {
+               printk(KERN_ERR "perfmon: cannot unregister format, not 
found\n");
+               ret = -EINVAL;
+               goto out;
+       }
+       list_del_init(&fmt->fmt_list);
+       printk(KERN_INFO "perfmon: removed sampling format: %s\n", 
fmt->fmt_name);
+
+out:
+       spin_unlock(&pfm_buffer_fmt_lock);
+       return ret;
+
+}
+EXPORT_SYMBOL(pfm_unregister_buffer_fmt);
+
+extern void update_pal_halt_status(int);
+
+static int
+pfm_reserve_session(struct task_struct *task, int is_syswide, unsigned int cpu)
+{
+       unsigned long flags;
+       /*
+        * validy checks on cpu_mask have been done upstream
+        */
+       LOCK_PFS(flags);
+
+       DPRINT(("in sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d 
cpu=%u\n",
+               pfm_sessions.pfs_sys_sessions,
+               pfm_sessions.pfs_task_sessions,
+               pfm_sessions.pfs_sys_use_dbregs,
+               is_syswide,
+               cpu));
+
+       if (is_syswide) {
+               /*
+                * cannot mix system wide and per-task sessions
+                */
+               if (pfm_sessions.pfs_task_sessions > 0UL) {
+                       DPRINT(("system wide not possible, %u conflicting 
task_sessions\n",
+                               pfm_sessions.pfs_task_sessions));
+                       goto abort;
+               }
+
+               if (pfm_sessions.pfs_sys_session[cpu]) goto error_conflict;
+
+               DPRINT(("reserving system wide session on CPU%u currently on 
CPU%u\n", cpu, smp_processor_id()));
+
+               pfm_sessions.pfs_sys_session[cpu] = task;
+
+               pfm_sessions.pfs_sys_sessions++ ;
+
+       } else {
+               if (pfm_sessions.pfs_sys_sessions) goto abort;
+               pfm_sessions.pfs_task_sessions++;
+       }
+
+       DPRINT(("out sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d 
cpu=%u\n",
+               pfm_sessions.pfs_sys_sessions,
+               pfm_sessions.pfs_task_sessions,
+               pfm_sessions.pfs_sys_use_dbregs,
+               is_syswide,
+               cpu));
+
+       /*
+        * disable default_idle() to go to PAL_HALT
+        */
+       update_pal_halt_status(0);
+
+       UNLOCK_PFS(flags);
+
+       return 0;
+
+error_conflict:
+       DPRINT(("system wide not possible, conflicting session [%d] on CPU%d\n",
+               pfm_sessions.pfs_sys_session[cpu]->pid,
+               cpu));
+abort:
+       UNLOCK_PFS(flags);
+
+       return -EBUSY;
+
+}
+
+static int
+pfm_unreserve_session(pfm_context_t *ctx, int is_syswide, unsigned int cpu)
+{
+       unsigned long flags;
+       /*
+        * validy checks on cpu_mask have been done upstream
+        */
+       LOCK_PFS(flags);
+
+       DPRINT(("in sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d 
cpu=%u\n",
+               pfm_sessions.pfs_sys_sessions,
+               pfm_sessions.pfs_task_sessions,
+               pfm_sessions.pfs_sys_use_dbregs,
+               is_syswide,
+               cpu));
+
+
+       if (is_syswide) {
+               pfm_sessions.pfs_sys_session[cpu] = NULL;
+               /*
+                * would not work with perfmon+more than one bit in cpu_mask
+                */
+               if (ctx && ctx->ctx_fl_using_dbreg) {
+                       if (pfm_sessions.pfs_sys_use_dbregs == 0) {
+                               printk(KERN_ERR "perfmon: invalid release for 
ctx %p sys_use_dbregs=0\n", ctx);
+                       } else {
+                               pfm_sessions.pfs_sys_use_dbregs--;
+                       }
+               }
+               pfm_sessions.pfs_sys_sessions--;
+       } else {
+               pfm_sessions.pfs_task_sessions--;
+       }
+       DPRINT(("out sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d 
cpu=%u\n",
+               pfm_sessions.pfs_sys_sessions,
+               pfm_sessions.pfs_task_sessions,
+               pfm_sessions.pfs_sys_use_dbregs,
+               is_syswide,
+               cpu));
+
+       /*
+        * if possible, enable default_idle() to go into PAL_HALT
+        */
+       if (pfm_sessions.pfs_task_sessions == 0 && 
pfm_sessions.pfs_sys_sessions == 0)
+               update_pal_halt_status(1);
+
+       UNLOCK_PFS(flags);
+
+       return 0;
+}
+
+/*
+ * removes virtual mapping of the sampling buffer.
+ * IMPORTANT: cannot be called with interrupts disable, e.g. inside
+ * a PROTECT_CTX() section.
+ */
+static int
+pfm_remove_smpl_mapping(struct task_struct *task, void *vaddr, unsigned long 
size)
+{
+       int r;
+
+       /* sanity checks */
+       if (task->mm == NULL || size == 0UL || vaddr == NULL) {
+               printk(KERN_ERR "perfmon: pfm_remove_smpl_mapping [%d] invalid 
context mm=%p\n", task->pid, task->mm);
+               return -EINVAL;
+       }
+
+       DPRINT(("smpl_vaddr=%p size=%lu\n", vaddr, size));
+
+       /*
+        * does the actual unmapping
+        */
+       down_write(&task->mm->mmap_sem);
+
+       DPRINT(("down_write done smpl_vaddr=%p size=%lu\n", vaddr, size));
+
+       r = pfm_do_munmap(task->mm, (unsigned long)vaddr, size, 0);
+
+       up_write(&task->mm->mmap_sem);
+       if (r !=0) {
+               printk(KERN_ERR "perfmon: [%d] unable to unmap sampling buffer 
@%p size=%lu\n", task->pid, vaddr, size);
+       }
+
+       DPRINT(("do_unmap(%p, %lu)=%d\n", vaddr, size, r));
+
+       return 0;
+}
+
+/*
+ * free actual physical storage used by sampling buffer
+ */
+#if 0
+static int
+pfm_free_smpl_buffer(pfm_context_t *ctx)
+{
+       pfm_buffer_fmt_t *fmt;
+
+       if (ctx->ctx_smpl_hdr == NULL) goto invalid_free;
+
+       /*
+        * we won't use the buffer format anymore
+        */
+       fmt = ctx->ctx_buf_fmt;
+
+       DPRINT(("sampling buffer @%p size %lu vaddr=%p\n",
+               ctx->ctx_smpl_hdr,
+               ctx->ctx_smpl_size,
+               ctx->ctx_smpl_vaddr));
+
+       pfm_buf_fmt_exit(fmt, current, NULL, NULL);
+
+       /*
+        * free the buffer
+        */
+       pfm_rvfree(ctx->ctx_smpl_hdr, ctx->ctx_smpl_size);
+
+       ctx->ctx_smpl_hdr  = NULL;
+       ctx->ctx_smpl_size = 0UL;
+
+       return 0;
+
+invalid_free:
+       printk(KERN_ERR "perfmon: pfm_free_smpl_buffer [%d] no buffer\n", 
current->pid);
+       return -EINVAL;
+}
+#endif
+
+static inline void
+pfm_exit_smpl_buffer(pfm_buffer_fmt_t *fmt)
+{
+       if (fmt == NULL) return;
+
+       pfm_buf_fmt_exit(fmt, current, NULL, NULL);
+
+}
+
+/*
+ * pfmfs should _never_ be mounted by userland - too much of security hassle,
+ * no real gain from having the whole whorehouse mounted. So we don't need
+ * any operations on the root directory. However, we need a non-trivial
+ * d_name - pfm: will go nicely and kill the special-casing in procfs.
+ */
+static struct vfsmount *pfmfs_mnt;
+
+static int __init
+init_pfm_fs(void)
+{
+       int err = register_filesystem(&pfm_fs_type);
+       if (!err) {
+               pfmfs_mnt = kern_mount(&pfm_fs_type);
+               err = PTR_ERR(pfmfs_mnt);
+               if (IS_ERR(pfmfs_mnt))
+                       unregister_filesystem(&pfm_fs_type);
+               else
+                       err = 0;
+       }
+       return err;
+}
+
+static void __exit
+exit_pfm_fs(void)
+{
+       unregister_filesystem(&pfm_fs_type);
+       mntput(pfmfs_mnt);
+}
+
+static ssize_t
+pfm_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
+{
+       pfm_context_t *ctx;
+       pfm_msg_t *msg;
+       ssize_t ret;
+       unsigned long flags;
+       DECLARE_WAITQUEUE(wait, current);
+       if (PFM_IS_FILE(filp) == 0) {
+               printk(KERN_ERR "perfmon: pfm_poll: bad magic [%d]\n", 
current->pid);
+               return -EINVAL;
+       }
+
+       ctx = (pfm_context_t *)filp->private_data;
+       if (ctx == NULL) {
+               printk(KERN_ERR "perfmon: pfm_read: NULL ctx [%d]\n", 
current->pid);
+               return -EINVAL;
+       }
+
+       /*
+        * check even when there is no message
+        */
+       if (size < sizeof(pfm_msg_t)) {
+               DPRINT(("message is too small ctx=%p (>=%ld)\n", ctx, 
sizeof(pfm_msg_t)));
+               return -EINVAL;
+       }
+
+       PROTECT_CTX(ctx, flags);
+
+       /*
+        * put ourselves on the wait queue
+        */
+       add_wait_queue(&ctx->ctx_msgq_wait, &wait);
+
+
+       for(;;) {
+               /*
+                * check wait queue
+                */
+
+               set_current_state(TASK_INTERRUPTIBLE);
+
+               DPRINT(("head=%d tail=%d\n", ctx->ctx_msgq_head, 
ctx->ctx_msgq_tail));
+
+               ret = 0;
+               if(PFM_CTXQ_EMPTY(ctx) == 0) break;
+
+               UNPROTECT_CTX(ctx, flags);
+
+               /*
+                * check non-blocking read
+                */
+               ret = -EAGAIN;
+               if(filp->f_flags & O_NONBLOCK) break;
+
+               /*
+                * check pending signals
+                */
+               if(signal_pending(current)) {
+                       ret = -EINTR;
+                       break;
+               }
+               /*
+                * no message, so wait
+                */
+               schedule();
+
+               PROTECT_CTX(ctx, flags);
+       }
+       DPRINT(("[%d] back to running ret=%ld\n", current->pid, ret));
+       set_current_state(TASK_RUNNING);
+       remove_wait_queue(&ctx->ctx_msgq_wait, &wait);
+
+       if (ret < 0) goto abort;
+
+       ret = -EINVAL;
+       msg = pfm_get_next_msg(ctx);
+       if (msg == NULL) {
+               printk(KERN_ERR "perfmon: pfm_read no msg for ctx=%p [%d]\n", 
ctx, current->pid);
+               goto abort_locked;
+       }
+
+       DPRINT(("fd=%d type=%d\n", msg->pfm_gen_msg.msg_ctx_fd, 
msg->pfm_gen_msg.msg_type));
+
+       ret = -EFAULT;
+       if(copy_to_user(buf, msg, sizeof(pfm_msg_t)) == 0) ret = 
sizeof(pfm_msg_t);
+
+abort_locked:
+       UNPROTECT_CTX(ctx, flags);
+abort:
+       return ret;
+}
+
+static ssize_t
+pfm_write(struct file *file, const char __user *ubuf,
+                         size_t size, loff_t *ppos)
+{
+       DPRINT(("pfm_write called\n"));
+       return -EINVAL;
+}
+
+static unsigned int
+pfm_poll(struct file *filp, poll_table * wait)
+{
+       pfm_context_t *ctx;
+       unsigned long flags;
+       unsigned int mask = 0;
+
+       if (PFM_IS_FILE(filp) == 0) {
+               printk(KERN_ERR "perfmon: pfm_poll: bad magic [%d]\n", 
current->pid);
+               return 0;
+       }
+
+       ctx = (pfm_context_t *)filp->private_data;
+       if (ctx == NULL) {
+               printk(KERN_ERR "perfmon: pfm_poll: NULL ctx [%d]\n", 
current->pid);
+               return 0;
+       }
+
+
+       DPRINT(("pfm_poll ctx_fd=%d before poll_wait\n", ctx->ctx_fd));
+
+       poll_wait(filp, &ctx->ctx_msgq_wait, wait);
+
+       PROTECT_CTX(ctx, flags);
+
+       if (PFM_CTXQ_EMPTY(ctx) == 0)
+               mask =  POLLIN | POLLRDNORM;
+
+       UNPROTECT_CTX(ctx, flags);
+
+       DPRINT(("pfm_poll ctx_fd=%d mask=0x%x\n", ctx->ctx_fd, mask));
+
+       return mask;
+}
+
+static int
+pfm_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned 
long arg)
+{
+       DPRINT(("pfm_ioctl called\n"));
+       return -EINVAL;
+}
+
+/*
+ * interrupt cannot be masked when coming here
+ */
+static inline int
+pfm_do_fasync(int fd, struct file *filp, pfm_context_t *ctx, int on)
+{
+       int ret;
+
+       ret = fasync_helper (fd, filp, on, &ctx->ctx_async_queue);
+
+       DPRINT(("pfm_fasync called by [%d] on ctx_fd=%d on=%d async_queue=%p 
ret=%d\n",
+               current->pid,
+               fd,
+               on,
+               ctx->ctx_async_queue, ret));
+
+       return ret;
+}
+
+static int
+pfm_fasync(int fd, struct file *filp, int on)
+{
+       pfm_context_t *ctx;
+       int ret;
+
+       if (PFM_IS_FILE(filp) == 0) {
+               printk(KERN_ERR "perfmon: pfm_fasync bad magic [%d]\n", 
current->pid);
+               return -EBADF;
+       }
+
+       ctx = (pfm_context_t *)filp->private_data;
+       if (ctx == NULL) {
+               printk(KERN_ERR "perfmon: pfm_fasync NULL ctx [%d]\n", 
current->pid);
+               return -EBADF;
+       }
+       /*
+        * we cannot mask interrupts during this call because this may
+        * may go to sleep if memory is not readily avalaible.
+        *
+        * We are protected from the conetxt disappearing by the 
get_fd()/put_fd()
+        * done in caller. Serialization of this function is ensured by caller.
+        */
+       ret = pfm_do_fasync(fd, filp, ctx, on);
+
+
+       DPRINT(("pfm_fasync called on ctx_fd=%d on=%d async_queue=%p ret=%d\n",
+               fd,
+               on,
+               ctx->ctx_async_queue, ret));
+
+       return ret;
+}
+
+#ifdef CONFIG_SMP
+/*
+ * this function is exclusively called from pfm_close().
+ * The context is not protected at that time, nor are interrupts
+ * on the remote CPU. That's necessary to avoid deadlocks.
+ */
+static void
+pfm_syswide_force_stop(void *info)
+{
+       pfm_context_t   *ctx = (pfm_context_t *)info;
+       struct pt_regs *regs = task_pt_regs(current);
+       struct task_struct *owner;
+       unsigned long flags;
+       int ret;
+
+       if (ctx->ctx_cpu != smp_processor_id()) {
+               printk(KERN_ERR "perfmon: pfm_syswide_force_stop for CPU%d  but 
on CPU%d\n",
+                       ctx->ctx_cpu,
+                       smp_processor_id());
+               return;
+       }
+       owner = GET_PMU_OWNER();
+       if (owner != ctx->ctx_task) {
+               printk(KERN_ERR "perfmon: pfm_syswide_force_stop CPU%d 
unexpected owner [%d] instead of [%d]\n",
+                       smp_processor_id(),
+                       owner->pid, ctx->ctx_task->pid);
+               return;
+       }
+       if (GET_PMU_CTX() != ctx) {
+               printk(KERN_ERR "perfmon: pfm_syswide_force_stop CPU%d 
unexpected ctx %p instead of %p\n",
+                       smp_processor_id(),
+                       GET_PMU_CTX(), ctx);
+               return;
+       }
+
+       DPRINT(("on CPU%d forcing system wide stop for [%d]\n", 
smp_processor_id(), ctx->ctx_task->pid));       
+       /*
+        * the context is already protected in pfm_close(), we simply
+        * need to mask interrupts to avoid a PMU interrupt race on
+        * this CPU
+        */
+       local_irq_save(flags);
+
+       ret = pfm_context_unload(ctx, NULL, 0, regs);
+       if (ret) {
+               DPRINT(("context_unload returned %d\n", ret));
+       }
+
+       /*
+        * unmask interrupts, PMU interrupts are now spurious here
+        */
+       local_irq_restore(flags);
+}
+
+static void
+pfm_syswide_cleanup_other_cpu(pfm_context_t *ctx)
+{
+       int ret;
+
+       DPRINT(("calling CPU%d for cleanup\n", ctx->ctx_cpu));
+       ret = smp_call_function_single(ctx->ctx_cpu, pfm_syswide_force_stop, 
ctx, 0, 1);
+       DPRINT(("called CPU%d for cleanup ret=%d\n", ctx->ctx_cpu, ret));
+}
+#endif /* CONFIG_SMP */
+
+/*
+ * called for each close(). Partially free resources.
+ * When caller is self-monitoring, the context is unloaded.
+ */
+static int
+pfm_flush(struct file *filp)
+{
+       pfm_context_t *ctx;
+       struct task_struct *task;
+       struct pt_regs *regs;
+       unsigned long flags;
+       unsigned long smpl_buf_size = 0UL;
+       void *smpl_buf_vaddr = NULL;
+       int state, is_system;
+
+       if (PFM_IS_FILE(filp) == 0) {
+               DPRINT(("bad magic for\n"));
+               return -EBADF;
+       }
+
+       ctx = (pfm_context_t *)filp->private_data;
+       if (ctx == NULL) {
+               printk(KERN_ERR "perfmon: pfm_flush: NULL ctx [%d]\n", 
current->pid);
+               return -EBADF;
+       }
+
+       /*
+        * remove our file from the async queue, if we use this mode.
+        * This can be done without the context being protected. We come
+        * here when the context has become unreacheable by other tasks.
+        *
+        * We may still have active monitoring at this point and we may
+        * end up in pfm_overflow_handler(). However, fasync_helper()
+        * operates with interrupts disabled and it cleans up the
+        * queue. If the PMU handler is called prior to entering
+        * fasync_helper() then it will send a signal. If it is
+        * invoked after, it will find an empty queue and no
+        * signal will be sent. In both case, we are safe
+        */
+       if (filp->f_flags & FASYNC) {
+               DPRINT(("cleaning up async_queue=%p\n", ctx->ctx_async_queue));
+               pfm_do_fasync (-1, filp, ctx, 0);
+       }
+
+       PROTECT_CTX(ctx, flags);
+
+       state     = ctx->ctx_state;
+       is_system = ctx->ctx_fl_system;
+
+       task = PFM_CTX_TASK(ctx);
+       regs = task_pt_regs(task);
+
+       DPRINT(("ctx_state=%d is_current=%d\n",
+               state,
+               task == current ? 1 : 0));
+
+       /*
+        * if state == UNLOADED, then task is NULL
+        */
+
+       /*
+        * we must stop and unload because we are losing access to the context.
+        */
+       if (task == current) {
+#ifdef CONFIG_SMP
+               /*
+                * the task IS the owner but it migrated to another CPU: that's 
bad
+                * but we must handle this cleanly. Unfortunately, the kernel 
does
+                * not provide a mechanism to block migration (while the 
context is loaded).
+                *
+                * We need to release the resource on the ORIGINAL cpu.
+                */
+               if (is_system && ctx->ctx_cpu != smp_processor_id()) {
+
+                       DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+                       /*
+                        * keep context protected but unmask interrupt for IPI
+                        */
+                       local_irq_restore(flags);
+
+                       pfm_syswide_cleanup_other_cpu(ctx);
+
+                       /*
+                        * restore interrupt masking
+                        */
+                       local_irq_save(flags);
+
+                       /*
+                        * context is unloaded at this point
+                        */
+               } else
+#endif /* CONFIG_SMP */
+               {
+
+                       DPRINT(("forcing unload\n"));
+                       /*
+                       * stop and unload, returning with state UNLOADED
+                       * and session unreserved.
+                       */
+                       pfm_context_unload(ctx, NULL, 0, regs);
+
+                       DPRINT(("ctx_state=%d\n", ctx->ctx_state));
+               }
+       }
+
+       /*
+        * remove virtual mapping, if any, for the calling task.
+        * cannot reset ctx field until last user is calling close().
+        *
+        * ctx_smpl_vaddr must never be cleared because it is needed
+        * by every task with access to the context
+        *
+        * When called from do_exit(), the mm context is gone already, therefore
+        * mm is NULL, i.e., the VMA is already gone  and we do not have to
+        * do anything here
+        */
+       if (ctx->ctx_smpl_vaddr && current->mm) {
+               smpl_buf_vaddr = ctx->ctx_smpl_vaddr;
+               smpl_buf_size  = ctx->ctx_smpl_size;
+       }
+
+       UNPROTECT_CTX(ctx, flags);
+
+       /*
+        * if there was a mapping, then we systematically remove it
+        * at this point. Cannot be done inside critical section
+        * because some VM function reenables interrupts.
+        *
+        */
+       if (smpl_buf_vaddr) pfm_remove_smpl_mapping(current, smpl_buf_vaddr, 
smpl_buf_size);
+
+       return 0;
+}
+/*
+ * called either on explicit close() or from exit_files(). 
+ * Only the LAST user of the file gets to this point, i.e., it is
+ * called only ONCE.
+ *
+ * IMPORTANT: we get called ONLY when the refcnt on the file gets to zero 
+ * (fput()),i.e, last task to access the file. Nobody else can access the 
+ * file at this point.
+ *
+ * When called from exit_files(), the VMA has been freed because exit_mm()
+ * is executed before exit_files().
+ *
+ * When called from exit_files(), the current task is not yet ZOMBIE but we
+ * flush the PMU state to the context. 
+ */
+static int
+pfm_close(struct inode *inode, struct file *filp)
+{
+       pfm_context_t *ctx;
+       struct task_struct *task;
+       struct pt_regs *regs;
+       DECLARE_WAITQUEUE(wait, current);
+       unsigned long flags;
+       unsigned long smpl_buf_size = 0UL;
+       void *smpl_buf_addr = NULL;
+       int free_possible = 1;
+       int state, is_system;
+
+       DPRINT(("pfm_close called private=%p\n", filp->private_data));
+
+       if (PFM_IS_FILE(filp) == 0) {
+               DPRINT(("bad magic\n"));
+               return -EBADF;
+       }
+       
+       ctx = (pfm_context_t *)filp->private_data;
+       if (ctx == NULL) {
+               printk(KERN_ERR "perfmon: pfm_close: NULL ctx [%d]\n", 
current->pid);
+               return -EBADF;
+       }
+
+       PROTECT_CTX(ctx, flags);
+
+       state     = ctx->ctx_state;
+       is_system = ctx->ctx_fl_system;
+
+       task = PFM_CTX_TASK(ctx);
+       regs = task_pt_regs(task);
+
+       DPRINT(("ctx_state=%d is_current=%d\n", 
+               state,
+               task == current ? 1 : 0));
+
+       /*
+        * if task == current, then pfm_flush() unloaded the context
+        */
+       if (state == PFM_CTX_UNLOADED) goto doit;
+
+       /*
+        * context is loaded/masked and task != current, we need to
+        * either force an unload or go zombie
+        */
+
+       /*
+        * The task is currently blocked or will block after an overflow.
+        * we must force it to wakeup to get out of the
+        * MASKED state and transition to the unloaded state by itself.
+        *
+        * This situation is only possible for per-task mode
+        */
+       if (state == PFM_CTX_MASKED && CTX_OVFL_NOBLOCK(ctx) == 0) {
+
+               /*
+                * set a "partial" zombie state to be checked
+                * upon return from down() in pfm_handle_work().
+                *
+                * We cannot use the ZOMBIE state, because it is checked
+                * by pfm_load_regs() which is called upon wakeup from down().
+                * In such case, it would free the context and then we would
+                * return to pfm_handle_work() which would access the
+                * stale context. Instead, we set a flag invisible to 
pfm_load_regs()
+                * but visible to pfm_handle_work().
+                *
+                * For some window of time, we have a zombie context with
+                * ctx_state = MASKED  and not ZOMBIE
+                */
+               ctx->ctx_fl_going_zombie = 1;
+
+               /*
+                * force task to wake up from MASKED state
+                */
+               complete(&ctx->ctx_restart_done);
+
+               DPRINT(("waking up ctx_state=%d\n", state));
+
+               /*
+                * put ourself to sleep waiting for the other
+                * task to report completion
+                *
+                * the context is protected by mutex, therefore there
+                * is no risk of being notified of completion before
+                * begin actually on the waitq.
+                */
+               set_current_state(TASK_INTERRUPTIBLE);
+               add_wait_queue(&ctx->ctx_zombieq, &wait);
+
+               UNPROTECT_CTX(ctx, flags);
+
+               /*
+                * XXX: check for signals :
+                *      - ok for explicit close
+                *      - not ok when coming from exit_files()
+                */
+               schedule();
+
+
+               PROTECT_CTX(ctx, flags);
+
+
+               remove_wait_queue(&ctx->ctx_zombieq, &wait);
+               set_current_state(TASK_RUNNING);
+
+               /*
+                * context is unloaded at this point
+                */
+               DPRINT(("after zombie wakeup ctx_state=%d for\n", state));
+       }
+       else if (task != current) {
+#ifdef CONFIG_SMP
+               /*
+                * switch context to zombie state
+                */
+               ctx->ctx_state = PFM_CTX_ZOMBIE;
+
+               DPRINT(("zombie ctx for [%d]\n", task->pid));
+               /*
+                * cannot free the context on the spot. deferred until
+                * the task notices the ZOMBIE state
+                */
+               free_possible = 0;
+#else
+               pfm_context_unload(ctx, NULL, 0, regs);
+#endif
+       }
+
+doit:
+       /* reload state, may have changed during  opening of critical section */
+       state = ctx->ctx_state;
+
+       /*
+        * the context is still attached to a task (possibly current)
+        * we cannot destroy it right now
+        */
+
+       /*
+        * we must free the sampling buffer right here because
+        * we cannot rely on it being cleaned up later by the
+        * monitored task. It is not possible to free vmalloc'ed
+        * memory in pfm_load_regs(). Instead, we remove the buffer
+        * now. should there be subsequent PMU overflow originally
+        * meant for sampling, the will be converted to spurious
+        * and that's fine because the monitoring tools is gone anyway.
+        */
+       if (ctx->ctx_smpl_hdr) {
+               smpl_buf_addr = ctx->ctx_smpl_hdr;
+               smpl_buf_size = ctx->ctx_smpl_size;
+               /* no more sampling */
+               ctx->ctx_smpl_hdr = NULL;
+               ctx->ctx_fl_is_sampling = 0;
+       }
+
+       DPRINT(("ctx_state=%d free_possible=%d addr=%p size=%lu\n",
+               state,
+               free_possible,
+               smpl_buf_addr,
+               smpl_buf_size));
+
+       if (smpl_buf_addr) pfm_exit_smpl_buffer(ctx->ctx_buf_fmt);
+
+       /*
+        * UNLOADED that the session has already been unreserved.
+        */
+       if (state == PFM_CTX_ZOMBIE) {
+               pfm_unreserve_session(ctx, ctx->ctx_fl_system , ctx->ctx_cpu);
+       }
+
+       /*
+        * disconnect file descriptor from context must be done
+        * before we unlock.
+        */
+       filp->private_data = NULL;
+
+       /*
+        * if we free on the spot, the context is now completely unreacheable
+        * from the callers side. The monitored task side is also cut, so we
+        * can freely cut.
+        *
+        * If we have a deferred free, only the caller side is disconnected.
+        */
+       UNPROTECT_CTX(ctx, flags);
+
+       /*
+        * All memory free operations (especially for vmalloc'ed memory)
+        * MUST be done with interrupts ENABLED.
+        */
+       if (smpl_buf_addr)  pfm_rvfree(smpl_buf_addr, smpl_buf_size);
+
+       /*
+        * return the memory used by the context
+        */
+       if (free_possible) pfm_context_free(ctx);
+
+       return 0;
+}
+
+static int
+pfm_no_open(struct inode *irrelevant, struct file *dontcare)
+{
+       DPRINT(("pfm_no_open called\n"));
+       return -ENXIO;
+}
+
+
+
+static struct file_operations pfm_file_ops = {
+       .llseek   = no_llseek,
+       .read     = pfm_read,
+       .write    = pfm_write,
+       .poll     = pfm_poll,
+       .ioctl    = pfm_ioctl,
+       .open     = pfm_no_open,        /* special open code to disallow open 
via /proc */
+       .fasync   = pfm_fasync,
+       .release  = pfm_close,
+       .flush    = pfm_flush
+};
+
+static int
+pfmfs_delete_dentry(struct dentry *dentry)
+{
+       return 1;
+}
+
+static struct dentry_operations pfmfs_dentry_operations = {
+       .d_delete = pfmfs_delete_dentry,
+};
+
+
+static int
+pfm_alloc_fd(struct file **cfile)
+{
+       int fd, ret = 0;
+       struct file *file = NULL;
+       struct inode * inode;
+       char name[32];
+       struct qstr this;
+
+       fd = get_unused_fd();
+       if (fd < 0) return -ENFILE;
+
+       ret = -ENFILE;
+
+       file = get_empty_filp();
+       if (!file) goto out;
+
+       /*
+        * allocate a new inode
+        */
+       inode = new_inode(pfmfs_mnt->mnt_sb);
+       if (!inode) goto out;
+
+       DPRINT(("new inode ino=%ld @%p\n", inode->i_ino, inode));
+
+       inode->i_mode = S_IFCHR|S_IRUGO;
+       inode->i_uid  = current->fsuid;
+       inode->i_gid  = current->fsgid;
+
+       sprintf(name, "[%lu]", inode->i_ino);
+       this.name = name;
+       this.len  = strlen(name);
+       this.hash = inode->i_ino;
+
+       ret = -ENOMEM;
+
+       /*
+        * allocate a new dcache entry
+        */
+       file->f_dentry = d_alloc(pfmfs_mnt->mnt_sb->s_root, &this);
+       if (!file->f_dentry) goto out;
+
+       file->f_dentry->d_op = &pfmfs_dentry_operations;
+
+       d_add(file->f_dentry, inode);
+       file->f_vfsmnt = mntget(pfmfs_mnt);
+       file->f_mapping = inode->i_mapping;
+
+       file->f_op    = &pfm_file_ops;
+       file->f_mode  = FMODE_READ;
+       file->f_flags = O_RDONLY;
+       file->f_pos   = 0;
+
+       /*
+        * may have to delay until context is attached?
+        */
+       fd_install(fd, file);
+
+       /*
+        * the file structure we will use
+        */
+       *cfile = file;
+
+       return fd;
+out:
+       if (file) put_filp(file);
+       put_unused_fd(fd);
+       return ret;
+}
+
+static void
+pfm_free_fd(int fd, struct file *file)
+{
+       struct files_struct *files = current->files;
+       struct fdtable *fdt;
+
+       /* 
+        * there ie no fd_uninstall(), so we do it here
+        */
+       spin_lock(&files->file_lock);
+       fdt = files_fdtable(files);
+       rcu_assign_pointer(fdt->fd[fd], NULL);
+       spin_unlock(&files->file_lock);
+
+       if (file)
+               put_filp(file);
+       put_unused_fd(fd);
+}
+
+static int
+pfm_remap_buffer(struct vm_area_struct *vma, unsigned long buf, unsigned long 
addr, unsigned long size)
+{
+       DPRINT(("CPU%d buf=0x%lx addr=0x%lx size=%ld\n", smp_processor_id(), 
buf, addr, size));
+
+       while (size > 0) {
+               unsigned long pfn = ia64_tpa(buf) >> PAGE_SHIFT;
+
+
+               if (remap_pfn_range(vma, addr, pfn, PAGE_SIZE, PAGE_READONLY))
+                       return -ENOMEM;
+
+               addr  += PAGE_SIZE;
+               buf   += PAGE_SIZE;
+               size  -= PAGE_SIZE;
+       }
+       return 0;
+}
+
+/*
+ * allocate a sampling buffer and remaps it into the user address space of the 
task
+ */
+static int
+pfm_smpl_buffer_alloc(struct task_struct *task, pfm_context_t *ctx, unsigned 
long rsize, void **user_vaddr)
+{
+       struct mm_struct *mm = task->mm;
+       struct vm_area_struct *vma = NULL;
+       unsigned long size;
+       void *smpl_buf;
+
+
+       /*
+        * the fixed header + requested size and align to page boundary
+        */
+       size = PAGE_ALIGN(rsize);
+
+       DPRINT(("sampling buffer rsize=%lu size=%lu bytes\n", rsize, size));
+
+       /*
+        * check requested size to avoid Denial-of-service attacks
+        * XXX: may have to refine this test
+        * Check against address space limit.
+        *
+        * if ((mm->total_vm << PAGE_SHIFT) + len> 
task->rlim[RLIMIT_AS].rlim_cur)
+        *      return -ENOMEM;
+        */
+       if (size > task->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
+               return -ENOMEM;
+
+       /*
+        * We do the easy to undo allocations first.
+        *
+        * pfm_rvmalloc(), clears the buffer, so there is no leak
+        */
+       smpl_buf = pfm_rvmalloc(size);
+       if (smpl_buf == NULL) {
+               DPRINT(("Can't allocate sampling buffer\n"));
+               return -ENOMEM;
+       }
+
+       DPRINT(("smpl_buf @%p\n", smpl_buf));
+
+       /* allocate vma */
+       vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+       if (!vma) {
+               DPRINT(("Cannot allocate vma\n"));
+               goto error_kmem;
+       }
+       memset(vma, 0, sizeof(*vma));
+
+       /*
+        * partially initialize the vma for the sampling buffer
+        */
+       vma->vm_mm           = mm;
+       vma->vm_flags        = VM_READ| VM_MAYREAD |VM_RESERVED;
+       vma->vm_page_prot    = PAGE_READONLY; /* XXX may need to change */
+
+       /*
+        * Now we have everything we need and we can initialize
+        * and connect all the data structures
+        */
+
+       ctx->ctx_smpl_hdr   = smpl_buf;
+       ctx->ctx_smpl_size  = size; /* aligned size */
+
+       /*
+        * Let's do the difficult operations next.
+        *
+        * now we atomically find some area in the address space and
+        * remap the buffer in it.
+        */
+       down_write(&task->mm->mmap_sem);
+
+       /* find some free area in address space, must have mmap sem held */
+       vma->vm_start = pfm_get_unmapped_area(NULL, 0, size, 0, 
MAP_PRIVATE|MAP_ANONYMOUS, 0);
+       if (vma->vm_start == 0UL) {
+               DPRINT(("Cannot find unmapped area for size %ld\n", size));
+               up_write(&task->mm->mmap_sem);
+               goto error;
+       }
+       vma->vm_end = vma->vm_start + size;
+       vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
+
+       DPRINT(("aligned size=%ld, hdr=%p mapped @0x%lx\n", size, 
ctx->ctx_smpl_hdr, vma->vm_start));
+
+       /* can only be applied to current task, need to have the mm semaphore 
held when called */
+       if (pfm_remap_buffer(vma, (unsigned long)smpl_buf, vma->vm_start, 
size)) {
+               DPRINT(("Can't remap buffer\n"));
+               up_write(&task->mm->mmap_sem);
+               goto error;
+       }
+
+       /*
+        * now insert the vma in the vm list for the process, must be
+        * done with mmap lock held
+        */
+       insert_vm_struct(mm, vma);
+
+       mm->total_vm  += size >> PAGE_SHIFT;
+       vm_stat_account(vma->vm_mm, vma->vm_flags, vma->vm_file,
+                                                       vma_pages(vma));
+       up_write(&task->mm->mmap_sem);
+
+       /*
+        * keep track of user level virtual address
+        */
+       ctx->ctx_smpl_vaddr = (void *)vma->vm_start;
+       *(unsigned long *)user_vaddr = vma->vm_start;
+
+       return 0;
+
+error:
+       kmem_cache_free(vm_area_cachep, vma);
+error_kmem:
+       pfm_rvfree(smpl_buf, size);
+
+       return -ENOMEM;
+}
+
+/*
+ * XXX: do something better here
+ */
+static int
+pfm_bad_permissions(struct task_struct *task)
+{
+       /* inspired by ptrace_attach() */
+       DPRINT(("cur: uid=%d gid=%d task: euid=%d suid=%d uid=%d egid=%d 
sgid=%d\n",
+               current->uid,
+               current->gid,
+               task->euid,
+               task->suid,
+               task->uid,
+               task->egid,
+               task->sgid));
+
+       return ((current->uid != task->euid)
+           || (current->uid != task->suid)
+           || (current->uid != task->uid)
+           || (current->gid != task->egid)
+           || (current->gid != task->sgid)
+           || (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE);
+}
+
+static int
+pfarg_is_sane(struct task_struct *task, pfarg_context_t *pfx)
+{
+       int ctx_flags;
+
+       /* valid signal */
+
+       ctx_flags = pfx->ctx_flags;
+
+       if (ctx_flags & PFM_FL_SYSTEM_WIDE) {
+
+               /*
+                * cannot block in this mode
+                */
+               if (ctx_flags & PFM_FL_NOTIFY_BLOCK) {
+                       DPRINT(("cannot use blocking mode when in system wide 
monitoring\n"));
+                       return -EINVAL;
+               }
+       } else {
+       }
+       /* probably more to add here */
+
+       return 0;
+}
+
+static int
+pfm_setup_buffer_fmt(struct task_struct *task, pfm_context_t *ctx, unsigned 
int ctx_flags,
+                    unsigned int cpu, pfarg_context_t *arg)
+{
+       pfm_buffer_fmt_t *fmt = NULL;
+       unsigned long size = 0UL;
+       void *uaddr = NULL;
+       void *fmt_arg = NULL;
+       int ret = 0;
+#define PFM_CTXARG_BUF_ARG(a)  (pfm_buffer_fmt_t *)(a+1)
+
+       /* invoke and lock buffer format, if found */
+       fmt = pfm_find_buffer_fmt(arg->ctx_smpl_buf_id);
+       if (fmt == NULL) {
+               DPRINT(("[%d] cannot find buffer format\n", task->pid));
+               return -EINVAL;
+       }
+
+       /*
+        * buffer argument MUST be contiguous to pfarg_context_t
+        */
+       if (fmt->fmt_arg_size) fmt_arg = PFM_CTXARG_BUF_ARG(arg);
+
+       ret = pfm_buf_fmt_validate(fmt, task, ctx_flags, cpu, fmt_arg);
+
+       DPRINT(("[%d] after validate(0x%x,%d,%p)=%d\n", task->pid, ctx_flags, 
cpu, fmt_arg, ret));
+
+       if (ret) goto error;
+
+       /* link buffer format and context */
+       ctx->ctx_buf_fmt = fmt;
+
+       /*
+        * check if buffer format wants to use perfmon buffer 
allocation/mapping service
+        */
+       ret = pfm_buf_fmt_getsize(fmt, task, ctx_flags, cpu, fmt_arg, &size);
+       if (ret) goto error;
+
+       if (size) {
+               /*
+                * buffer is always remapped into the caller's address space
+                */
+               ret = pfm_smpl_buffer_alloc(current, ctx, size, &uaddr);
+               if (ret) goto error;
+
+               /* keep track of user address of buffer */
+               arg->ctx_smpl_vaddr = uaddr;
+       }
+       ret = pfm_buf_fmt_init(fmt, task, ctx->ctx_smpl_hdr, ctx_flags, cpu, 
fmt_arg);
+
+error:
+       return ret;
+}
+
+static void
+pfm_reset_pmu_state(pfm_context_t *ctx)
+{
+       int i;
+
+       /*
+        * install reset values for PMC.
+        */
+       for (i=1; PMC_IS_LAST(i) == 0; i++) {
+               if (PMC_IS_IMPL(i) == 0) continue;
+               ctx->ctx_pmcs[i] = PMC_DFL_VAL(i);
+               DPRINT(("pmc[%d]=0x%lx\n", i, ctx->ctx_pmcs[i]));
+       }
+       /*
+        * PMD registers are set to 0UL when the context in memset()
+        */
+
+       /*
+        * On context switched restore, we must restore ALL pmc and ALL pmd even
+        * when they are not actively used by the task. In UP, the incoming 
process
+        * may otherwise pick up left over PMC, PMD state from the previous 
process.
+        * As opposed to PMD, stale PMC can cause harm to the incoming
+        * process because they may change what is being measured.
+        * Therefore, we must systematically reinstall the entire
+        * PMC state. In SMP, the same thing is possible on the
+        * same CPU but also on between 2 CPUs.
+        *
+        * The problem with PMD is information leaking especially
+        * to user level when psr.sp=0
+        *
+        * There is unfortunately no easy way to avoid this problem
+        * on either UP or SMP. This definitively slows down the
+        * pfm_load_regs() function.
+        */
+
+        /*
+         * bitmask of all PMCs accessible to this context
+         *
+         * PMC0 is treated differently.
+         */
+       ctx->ctx_all_pmcs[0] = pmu_conf->impl_pmcs[0] & ~0x1;
+
+       /*
+        * bitmask of all PMDs that are accesible to this context
+        */
+       ctx->ctx_all_pmds[0] = pmu_conf->impl_pmds[0];
+
+       DPRINT(("<%d> all_pmcs=0x%lx all_pmds=0x%lx\n", ctx->ctx_fd, 
ctx->ctx_all_pmcs[0],ctx->ctx_all_pmds[0]));
+
+       /*
+        * useful in case of re-enable after disable
+        */
+       ctx->ctx_used_ibrs[0] = 0UL;
+       ctx->ctx_used_dbrs[0] = 0UL;
+}
+
+static int
+pfm_ctx_getsize(void *arg, size_t *sz)
+{
+       pfarg_context_t *req = (pfarg_context_t *)arg;
+       pfm_buffer_fmt_t *fmt;
+
+       *sz = 0;
+
+       if (!pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) return 0;
+
+       fmt = pfm_find_buffer_fmt(req->ctx_smpl_buf_id);
+       if (fmt == NULL) {
+               DPRINT(("cannot find buffer format\n"));
+               return -EINVAL;
+       }
+       /* get just enough to copy in user parameters */
+       *sz = fmt->fmt_arg_size;
+       DPRINT(("arg_size=%lu\n", *sz));
+
+       return 0;
+}
+
+
+
+/*
+ * cannot attach if :
+ *     - kernel task
+ *     - task not owned by caller
+ *     - task incompatible with context mode
+ */
+static int
+pfm_task_incompatible(pfm_context_t *ctx, struct task_struct *task)
+{
+       /*
+        * no kernel task or task not owner by caller
+        */
+       if (task->mm == NULL) {
+               DPRINT(("task [%d] has not memory context (kernel thread)\n", 
task->pid));
+               return -EPERM;
+       }
+       if (pfm_bad_permissions(task)) {
+               DPRINT(("no permission to attach to  [%d]\n", task->pid));
+               return -EPERM;
+       }
+       /*
+        * cannot block in self-monitoring mode
+        */
+       if (CTX_OVFL_NOBLOCK(ctx) == 0 && task == current) {
+               DPRINT(("cannot load a blocking context on self for [%d]\n", 
task->pid));
+               return -EINVAL;
+       }
+
+       if (task->exit_state == EXIT_ZOMBIE) {
+               DPRINT(("cannot attach to  zombie task [%d]\n", task->pid));
+               return -EBUSY;
+       }
+
+       /*
+        * always ok for self
+        */
+       if (task == current) return 0;
+
+       if ((task->state != TASK_STOPPED) && (task->state != TASK_TRACED)) {
+               DPRINT(("cannot attach to non-stopped task [%d] state=%ld\n", 
task->pid, task->state));
+               return -EBUSY;
+       }
+       /*
+        * make sure the task is off any CPU
+        */
+       wait_task_inactive(task);
+
+       /* more to come... */
+
+       return 0;
+}
+
+static int
+pfm_get_task(pfm_context_t *ctx, pid_t pid, struct task_struct **task)
+{
+       struct task_struct *p = current;
+       int ret;
+
+       /* XXX: need to add more checks here */
+       if (pid < 2) return -EPERM;
+
+       if (pid != current->pid) {
+
+               read_lock(&tasklist_lock);
+
+               p = find_task_by_pid(pid);
+
+               /* make sure task cannot go away while we operate on it */
+               if (p) get_task_struct(p);
+
+               read_unlock(&tasklist_lock);
+
+               if (p == NULL) return -ESRCH;
+       }
+
+       ret = pfm_task_incompatible(ctx, p);
+       if (ret == 0) {
+               *task = p;
+       } else if (p != current) {
+               pfm_put_task(p);
+       }
+       return ret;
+}
+
+
+
+static int
+pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs 
*regs)
+{
+       pfarg_context_t *req = (pfarg_context_t *)arg;
+       struct file *filp;
+       int ctx_flags;
+       int ret;
+
+       /* let's check the arguments first */
+       ret = pfarg_is_sane(current, req);
+       if (ret < 0) return ret;
+
+       ctx_flags = req->ctx_flags;
+
+       ret = -ENOMEM;
+
+       ctx = pfm_context_alloc();
+       if (!ctx) goto error;
+
+       ret = pfm_alloc_fd(&filp);
+       if (ret < 0) goto error_file;
+
+       req->ctx_fd = ctx->ctx_fd = ret;
+
+       /*
+        * attach context to file
+        */
+       filp->private_data = ctx;
+
+       /*
+        * does the user want to sample?
+        */
+       if (pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) {
+               ret = pfm_setup_buffer_fmt(current, ctx, ctx_flags, 0, req);
+               if (ret) goto buffer_error;
+       }
+
+       /*
+        * init context protection lock
+        */
+       spin_lock_init(&ctx->ctx_lock);
+
+       /*
+        * context is unloaded
+        */
+       ctx->ctx_state = PFM_CTX_UNLOADED;
+
+       /*
+        * initialization of context's flags
+        */
+       ctx->ctx_fl_block       = (ctx_flags & PFM_FL_NOTIFY_BLOCK) ? 1 : 0;
+       ctx->ctx_fl_system      = (ctx_flags & PFM_FL_SYSTEM_WIDE) ? 1: 0;
+       ctx->ctx_fl_is_sampling = ctx->ctx_buf_fmt ? 1 : 0; /* assume record() 
is defined */
+       ctx->ctx_fl_no_msg      = (ctx_flags & PFM_FL_OVFL_NO_MSG) ? 1: 0;
+       /*
+        * will move to set properties
+        * ctx->ctx_fl_excl_idle   = (ctx_flags & PFM_FL_EXCL_IDLE) ? 1: 0;
+        */
+
+       /*
+        * init restart semaphore to locked
+        */
+       init_completion(&ctx->ctx_restart_done);
+
+       /*
+        * activation is used in SMP only
+        */
+       ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
+       SET_LAST_CPU(ctx, -1);
+
+       /*
+        * initialize notification message queue
+        */
+       ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0;
+       init_waitqueue_head(&ctx->ctx_msgq_wait);
+       init_waitqueue_head(&ctx->ctx_zombieq);
+
+       DPRINT(("ctx=%p flags=0x%x system=%d notify_block=%d excl_idle=%d 
no_msg=%d ctx_fd=%d \n",
+               ctx,
+               ctx_flags,
+               ctx->ctx_fl_system,
+               ctx->ctx_fl_block,
+               ctx->ctx_fl_excl_idle,
+               ctx->ctx_fl_no_msg,
+               ctx->ctx_fd));
+
+       /*
+        * initialize soft PMU state
+        */
+       pfm_reset_pmu_state(ctx);
+
+       return 0;
+
+buffer_error:
+       pfm_free_fd(ctx->ctx_fd, filp);
+
+       if (ctx->ctx_buf_fmt) {
+               pfm_buf_fmt_exit(ctx->ctx_buf_fmt, current, NULL, regs);
+       }
+error_file:
+       pfm_context_free(ctx);
+
+error:
+       return ret;
+}
+
+static inline unsigned long
+pfm_new_counter_value (pfm_counter_t *reg, int is_long_reset)
+{
+       unsigned long val = is_long_reset ? reg->long_reset : reg->short_reset;
+       unsigned long new_seed, old_seed = reg->seed, mask = reg->mask;
+       extern unsigned long carta_random32 (unsigned long seed);
+
+       if (reg->flags & PFM_REGFL_RANDOM) {
+               new_seed = carta_random32(old_seed);
+               val -= (old_seed & mask);       /* counter values are negative 
numbers! */
+               if ((mask >> 32) != 0)
+                       /* construct a full 64-bit random value: */
+                       new_seed |= carta_random32(old_seed >> 32) << 32;
+               reg->seed = new_seed;
+       }
+       reg->lval = val;
+       return val;
+}
+
+static void
+pfm_reset_regs_masked(pfm_context_t *ctx, unsigned long *ovfl_regs, int 
is_long_reset)
+{
+       unsigned long mask = ovfl_regs[0];
+       unsigned long reset_others = 0UL;
+       unsigned long val;
+       int i;
+
+       /*
+        * now restore reset value on sampling overflowed counters
+        */
+       mask >>= PMU_FIRST_COUNTER;
+       for(i = PMU_FIRST_COUNTER; mask; i++, mask >>= 1) {
+
+               if ((mask & 0x1UL) == 0UL) continue;
+
+               ctx->ctx_pmds[i].val = val = 
pfm_new_counter_value(ctx->ctx_pmds+ i, is_long_reset);
+               reset_others        |= ctx->ctx_pmds[i].reset_pmds[0];
+
+               DPRINT_ovfl((" %s reset ctx_pmds[%d]=%lx\n", is_long_reset ? 
"long" : "short", i, val));
+       }
+
+       /*
+        * Now take care of resetting the other registers
+        */
+       for(i = 0; reset_others; i++, reset_others >>= 1) {
+
+               if ((reset_others & 0x1) == 0) continue;
+
+               ctx->ctx_pmds[i].val = val = 
pfm_new_counter_value(ctx->ctx_pmds + i, is_long_reset);
+
+               DPRINT_ovfl(("%s reset_others pmd[%d]=%lx\n",
+                         is_long_reset ? "long" : "short", i, val));
+       }
+}
+
+static void
+pfm_reset_regs(pfm_context_t *ctx, unsigned long *ovfl_regs, int is_long_reset)
+{
+       unsigned long mask = ovfl_regs[0];
+       unsigned long reset_others = 0UL;
+       unsigned long val;
+       int i;
+
+       DPRINT_ovfl(("ovfl_regs=0x%lx is_long_reset=%d\n", ovfl_regs[0], 
is_long_reset));
+
+       if (ctx->ctx_state == PFM_CTX_MASKED) {
+               pfm_reset_regs_masked(ctx, ovfl_regs, is_long_reset);
+               return;
+       }
+
+       /*
+        * now restore reset value on sampling overflowed counters
+        */
+       mask >>= PMU_FIRST_COUNTER;
+       for(i = PMU_FIRST_COUNTER; mask; i++, mask >>= 1) {
+
+               if ((mask & 0x1UL) == 0UL) continue;
+
+               val           = pfm_new_counter_value(ctx->ctx_pmds+ i, 
is_long_reset);
+               reset_others |= ctx->ctx_pmds[i].reset_pmds[0];
+
+               DPRINT_ovfl((" %s reset ctx_pmds[%d]=%lx\n", is_long_reset ? 
"long" : "short", i, val));
+
+               pfm_write_soft_counter(ctx, i, val);
+       }
+
+       /*
+        * Now take care of resetting the other registers
+        */
+       for(i = 0; reset_others; i++, reset_others >>= 1) {
+
+               if ((reset_others & 0x1) == 0) continue;
+
+               val = pfm_new_counter_value(ctx->ctx_pmds + i, is_long_reset);
+
+               if (PMD_IS_COUNTING(i)) {
+                       pfm_write_soft_counter(ctx, i, val);
+               } else {
+                       ia64_set_pmd(i, val);
+               }
+               DPRINT_ovfl(("%s reset_others pmd[%d]=%lx\n",
+                         is_long_reset ? "long" : "short", i, val));
+       }
+       ia64_srlz_d();
+}
+
+static int
+pfm_write_pmcs(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       struct thread_struct *thread = NULL;
+       struct task_struct *task;
+       pfarg_reg_t *req = (pfarg_reg_t *)arg;
+       unsigned long value, pmc_pm;
+       unsigned long smpl_pmds, reset_pmds, impl_pmds;
+       unsigned int cnum, reg_flags, flags, pmc_type;
+       int i, can_access_pmu = 0, is_loaded, is_system, expert_mode;
+       int is_monitor, is_counting, state;
+       int ret = -EINVAL;
+       pfm_reg_check_t wr_func;
+#define PFM_CHECK_PMC_PM(x, y, z) ((x)->ctx_fl_system ^ PMC_PM(y, z))
+
+       state     = ctx->ctx_state;
+       is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
+       is_system = ctx->ctx_fl_system;
+       task      = ctx->ctx_task;
+       impl_pmds = pmu_conf->impl_pmds[0];
+
+       if (state == PFM_CTX_ZOMBIE) return -EINVAL;
+
+       if (is_loaded) {
+               thread = &task->thread;
+               /*
+                * In system wide and when the context is loaded, access can 
only happen
+                * when the caller is running on the CPU being monitored by the 
session.
+                * It does not have to be the owner (ctx_task) of the context 
per se.
+                */
+               if (is_system && ctx->ctx_cpu != smp_processor_id()) {
+                       DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+                       return -EBUSY;
+               }
+               can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
+       }
+       expert_mode = pfm_sysctl.expert_mode; 
+
+       for (i = 0; i < count; i++, req++) {
+
+               cnum       = req->reg_num;
+               reg_flags  = req->reg_flags;
+               value      = req->reg_value;
+               smpl_pmds  = req->reg_smpl_pmds[0];
+               reset_pmds = req->reg_reset_pmds[0];
+               flags      = 0;
+
+
+               if (cnum >= PMU_MAX_PMCS) {
+                       DPRINT(("pmc%u is invalid\n", cnum));
+                       goto error;
+               }
+
+               pmc_type   = pmu_conf->pmc_desc[cnum].type;
+               pmc_pm     = (value >> pmu_conf->pmc_desc[cnum].pm_pos) & 0x1;
+               is_counting = (pmc_type & PFM_REG_COUNTING) == PFM_REG_COUNTING 
? 1 : 0;
+               is_monitor  = (pmc_type & PFM_REG_MONITOR) == PFM_REG_MONITOR ? 
1 : 0;
+
+               /*
+                * we reject all non implemented PMC as well
+                * as attempts to modify PMC[0-3] which are used
+                * as status registers by the PMU
+                */
+               if ((pmc_type & PFM_REG_IMPL) == 0 || (pmc_type & 
PFM_REG_CONTROL) == PFM_REG_CONTROL) {
+                       DPRINT(("pmc%u is unimplemented or no-access 
pmc_type=%x\n", cnum, pmc_type));
+                       goto error;
+               }
+               wr_func = pmu_conf->pmc_desc[cnum].write_check;
+               /*
+                * If the PMC is a monitor, then if the value is not the 
default:
+                *      - system-wide session: PMCx.pm=1 (privileged monitor)
+                *      - per-task           : PMCx.pm=0 (user monitor)
+                */
+               if (is_monitor && value != PMC_DFL_VAL(cnum) && is_system ^ 
pmc_pm) {
+                       DPRINT(("pmc%u pmc_pm=%lu is_system=%d\n",
+                               cnum,
+                               pmc_pm,
+                               is_system));
+                       goto error;
+               }
+
+               if (is_counting) {
+                       /*
+                        * enforce generation of overflow interrupt. Necessary 
on all
+                        * CPUs.
+                        */
+                       value |= 1 << PMU_PMC_OI;
+
+                       if (reg_flags & PFM_REGFL_OVFL_NOTIFY) {
+                               flags |= PFM_REGFL_OVFL_NOTIFY;
+                       }
+
+                       if (reg_flags & PFM_REGFL_RANDOM) flags |= 
PFM_REGFL_RANDOM;
+
+                       /* verify validity of smpl_pmds */
+                       if ((smpl_pmds & impl_pmds) != smpl_pmds) {
+                               DPRINT(("invalid smpl_pmds 0x%lx for pmc%u\n", 
smpl_pmds, cnum));
+                               goto error;
+                       }
+
+                       /* verify validity of reset_pmds */
+                       if ((reset_pmds & impl_pmds) != reset_pmds) {
+                               DPRINT(("invalid reset_pmds 0x%lx for pmc%u\n", 
reset_pmds, cnum));
+                               goto error;
+                       }
+               } else {
+                       if (reg_flags & 
(PFM_REGFL_OVFL_NOTIFY|PFM_REGFL_RANDOM)) {
+                               DPRINT(("cannot set ovfl_notify or random on 
pmc%u\n", cnum));
+                               goto error;
+                       }
+                       /* eventid on non-counting monitors are ignored */
+               }
+
+               /*
+                * execute write checker, if any
+                */
+               if (likely(expert_mode == 0 && wr_func)) {
+                       ret = (*wr_func)(task, ctx, cnum, &value, regs);
+                       if (ret) goto error;
+                       ret = -EINVAL;
+               }
+
+               /*
+                * no error on this register
+                */
+               PFM_REG_RETFLAG_SET(req->reg_flags, 0);
+
+               /*
+                * Now we commit the changes to the software state
+                */
+
+               /*
+                * update overflow information
+                */
+               if (is_counting) {
+                       /*
+                        * full flag update each time a register is programmed
+                        */
+                       ctx->ctx_pmds[cnum].flags = flags;
+
+                       ctx->ctx_pmds[cnum].reset_pmds[0] = reset_pmds;
+                       ctx->ctx_pmds[cnum].smpl_pmds[0]  = smpl_pmds;
+                       ctx->ctx_pmds[cnum].eventid       = 
req->reg_smpl_eventid;
+
+                       /*
+                        * Mark all PMDS to be accessed as used.
+                        *
+                        * We do not keep track of PMC because we have to
+                        * systematically restore ALL of them.
+                        *
+                        * We do not update the used_monitors mask, because
+                        * if we have not programmed them, then will be in
+                        * a quiescent state, therefore we will not need to
+                        * mask/restore then when context is MASKED.
+                        */
+                       CTX_USED_PMD(ctx, reset_pmds);
+                       CTX_USED_PMD(ctx, smpl_pmds);
+                       /*
+                        * make sure we do not try to reset on
+                        * restart because we have established new values
+                        */
+                       if (state == PFM_CTX_MASKED) ctx->ctx_ovfl_regs[0] &= 
~1UL << cnum;
+               }
+               /*
+                * Needed in case the user does not initialize the equivalent
+                * PMD. Clearing is done indirectly via pfm_reset_pmu_state() 
so there is no
+                * possible leak here.
+                */
+               CTX_USED_PMD(ctx, pmu_conf->pmc_desc[cnum].dep_pmd[0]);
+
+               /*
+                * keep track of the monitor PMC that we are using.
+                * we save the value of the pmc in ctx_pmcs[] and if
+                * the monitoring is not stopped for the context we also
+                * place it in the saved state area so that it will be
+                * picked up later by the context switch code.
+                *
+                * The value in ctx_pmcs[] can only be changed in 
pfm_write_pmcs().
+                *
+                * The value in thread->pmcs[] may be modified on overflow, 
i.e.,  when
+                * monitoring needs to be stopped.
+                */
+               if (is_monitor) CTX_USED_MONITOR(ctx, 1UL << cnum);
+
+               /*
+                * update context state
+                */
+               ctx->ctx_pmcs[cnum] = value;
+
+               if (is_loaded) {
+                       /*
+                        * write thread state
+                        */
+                       if (is_system == 0) thread->pmcs[cnum] = value;
+
+                       /*
+                        * write hardware register if we can
+                        */
+                       if (can_access_pmu) {
+                               ia64_set_pmc(cnum, value);
+                       }
+#ifdef CONFIG_SMP
+                       else {
+                               /*
+                                * per-task SMP only here
+                                *
+                                * we are guaranteed that the task is not 
running on the other CPU,
+                                * we indicate that this PMD will need to be 
reloaded if the task
+                                * is rescheduled on the CPU it ran last on.
+                                */
+                               ctx->ctx_reload_pmcs[0] |= 1UL << cnum;
+                       }
+#endif
+               }
+
+               DPRINT(("pmc[%u]=0x%lx ld=%d apmu=%d flags=0x%x all_pmcs=0x%lx 
used_pmds=0x%lx eventid=%ld smpl_pmds=0x%lx reset_pmds=0x%lx reloads_pmcs=0x%lx 
used_monitors=0x%lx ovfl_regs=0x%lx\n",
+                         cnum,
+                         value,
+                         is_loaded,
+                         can_access_pmu,
+                         flags,
+                         ctx->ctx_all_pmcs[0],
+                         ctx->ctx_used_pmds[0],
+                         ctx->ctx_pmds[cnum].eventid,
+                         smpl_pmds,
+                         reset_pmds,
+                         ctx->ctx_reload_pmcs[0],
+                         ctx->ctx_used_monitors[0],
+                         ctx->ctx_ovfl_regs[0]));
+       }
+
+       /*
+        * make sure the changes are visible
+        */
+       if (can_access_pmu) ia64_srlz_d();
+
+       return 0;
+error:
+       PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
+       return ret;
+}
+
+static int
+pfm_write_pmds(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       struct thread_struct *thread = NULL;
+       struct task_struct *task;
+       pfarg_reg_t *req = (pfarg_reg_t *)arg;
+       unsigned long value, hw_value, ovfl_mask;
+       unsigned int cnum;
+       int i, can_access_pmu = 0, state;
+       int is_counting, is_loaded, is_system, expert_mode;
+       int ret = -EINVAL;
+       pfm_reg_check_t wr_func;
+
+
+       state     = ctx->ctx_state;
+       is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
+       is_system = ctx->ctx_fl_system;
+       ovfl_mask = pmu_conf->ovfl_val;
+       task      = ctx->ctx_task;
+
+       if (unlikely(state == PFM_CTX_ZOMBIE)) return -EINVAL;
+
+       /*
+        * on both UP and SMP, we can only write to the PMC when the task is
+        * the owner of the local PMU.
+        */
+       if (likely(is_loaded)) {
+               thread = &task->thread;
+               /*
+                * In system wide and when the context is loaded, access can 
only happen
+                * when the caller is running on the CPU being monitored by the 
session.
+                * It does not have to be the owner (ctx_task) of the context 
per se.
+                */
+               if (unlikely(is_system && ctx->ctx_cpu != smp_processor_id())) {
+                       DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+                       return -EBUSY;
+               }
+               can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
+       }
+       expert_mode = pfm_sysctl.expert_mode; 
+
+       for (i = 0; i < count; i++, req++) {
+
+               cnum  = req->reg_num;
+               value = req->reg_value;
+
+               if (!PMD_IS_IMPL(cnum)) {
+                       DPRINT(("pmd[%u] is unimplemented or invalid\n", cnum));
+                       goto abort_mission;
+               }
+               is_counting = PMD_IS_COUNTING(cnum);
+               wr_func     = pmu_conf->pmd_desc[cnum].write_check;
+
+               /*
+                * execute write checker, if any
+                */
+               if (unlikely(expert_mode == 0 && wr_func)) {
+                       unsigned long v = value;
+
+                       ret = (*wr_func)(task, ctx, cnum, &v, regs);
+                       if (ret) goto abort_mission;
+
+                       value = v;
+                       ret   = -EINVAL;
+               }
+
+               /*
+                * no error on this register
+                */
+               PFM_REG_RETFLAG_SET(req->reg_flags, 0);
+
+               /*
+                * now commit changes to software state
+                */
+               hw_value = value;
+
+               /*
+                * update virtualized (64bits) counter
+                */
+               if (is_counting) {
+                       /*
+                        * write context state
+                        */
+                       ctx->ctx_pmds[cnum].lval = value;
+
+                       /*
+                        * when context is load we use the split value
+                        */
+                       if (is_loaded) {
+                               hw_value = value &  ovfl_mask;
+                               value    = value & ~ovfl_mask;
+                       }
+               }
+               /*
+                * update reset values (not just for counters)
+                */
+               ctx->ctx_pmds[cnum].long_reset  = req->reg_long_reset;
+               ctx->ctx_pmds[cnum].short_reset = req->reg_short_reset;
+
+               /*
+                * update randomization parameters (not just for counters)
+                */
+               ctx->ctx_pmds[cnum].seed = req->reg_random_seed;
+               ctx->ctx_pmds[cnum].mask = req->reg_random_mask;
+
+               /*
+                * update context value
+                */
+               ctx->ctx_pmds[cnum].val  = value;
+
+               /*
+                * Keep track of what we use
+                *
+                * We do not keep track of PMC because we have to
+                * systematically restore ALL of them.
+                */
+               CTX_USED_PMD(ctx, PMD_PMD_DEP(cnum));
+
+               /*
+                * mark this PMD register used as well
+                */
+               CTX_USED_PMD(ctx, RDEP(cnum));
+
+               /*
+                * make sure we do not try to reset on
+                * restart because we have established new values
+                */
+               if (is_counting && state == PFM_CTX_MASKED) {
+                       ctx->ctx_ovfl_regs[0] &= ~1UL << cnum;
+               }
+
+               if (is_loaded) {
+                       /*
+                        * write thread state
+                        */
+                       if (is_system == 0) thread->pmds[cnum] = hw_value;
+
+                       /*
+                        * write hardware register if we can
+                        */
+                       if (can_access_pmu) {
+                               ia64_set_pmd(cnum, hw_value);
+                       } else {
+#ifdef CONFIG_SMP
+                               /*
+                                * we are guaranteed that the task is not 
running on the other CPU,
+                                * we indicate that this PMD will need to be 
reloaded if the task
+                                * is rescheduled on the CPU it ran last on.
+                                */
+                               ctx->ctx_reload_pmds[0] |= 1UL << cnum;
+#endif
+                       }
+               }
+
+               DPRINT(("pmd[%u]=0x%lx ld=%d apmu=%d, hw_value=0x%lx 
ctx_pmd=0x%lx  short_reset=0x%lx "
+                         "long_reset=0x%lx notify=%c seed=0x%lx mask=0x%lx 
used_pmds=0x%lx reset_pmds=0x%lx reload_pmds=0x%lx all_pmds=0x%lx 
ovfl_regs=0x%lx\n",
+                       cnum,
+                       value,
+                       is_loaded,
+                       can_access_pmu,
+                       hw_value,
+                       ctx->ctx_pmds[cnum].val,
+                       ctx->ctx_pmds[cnum].short_reset,
+                       ctx->ctx_pmds[cnum].long_reset,
+                       PMC_OVFL_NOTIFY(ctx, cnum) ? 'Y':'N',
+                       ctx->ctx_pmds[cnum].seed,
+                       ctx->ctx_pmds[cnum].mask,
+                       ctx->ctx_used_pmds[0],
+                       ctx->ctx_pmds[cnum].reset_pmds[0],
+                       ctx->ctx_reload_pmds[0],
+                       ctx->ctx_all_pmds[0],
+                       ctx->ctx_ovfl_regs[0]));
+       }
+
+       /*
+        * make changes visible
+        */
+       if (can_access_pmu) ia64_srlz_d();
+
+       return 0;
+
+abort_mission:
+       /*
+        * for now, we have only one possibility for error
+        */
+       PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
+       return ret;
+}
+
+/*
+ * By the way of PROTECT_CONTEXT(), interrupts are masked while we are in this 
function.
+ * Therefore we know, we do not have to worry about the PMU overflow 
interrupt. If an
+ * interrupt is delivered during the call, it will be kept pending until we 
leave, making
+ * it appears as if it had been generated at the UNPROTECT_CONTEXT(). At least 
we are
+ * guaranteed to return consistent data to the user, it may simply be old. It 
is not
+ * trivial to treat the overflow while inside the call because you may end up 
in
+ * some module sampling buffer code causing deadlocks.
+ */
+static int
+pfm_read_pmds(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       struct thread_struct *thread = NULL;
+       struct task_struct *task;
+       unsigned long val = 0UL, lval, ovfl_mask, sval;
+       pfarg_reg_t *req = (pfarg_reg_t *)arg;
+       unsigned int cnum, reg_flags = 0;
+       int i, can_access_pmu = 0, state;
+       int is_loaded, is_system, is_counting, expert_mode;
+       int ret = -EINVAL;
+       pfm_reg_check_t rd_func;
+
+       /*
+        * access is possible when loaded only for
+        * self-monitoring tasks or in UP mode
+        */
+
+       state     = ctx->ctx_state;
+       is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
+       is_system = ctx->ctx_fl_system;
+       ovfl_mask = pmu_conf->ovfl_val;
+       task      = ctx->ctx_task;
+
+       if (state == PFM_CTX_ZOMBIE) return -EINVAL;
+
+       if (likely(is_loaded)) {
+               thread = &task->thread;
+               /*
+                * In system wide and when the context is loaded, access can 
only happen
+                * when the caller is running on the CPU being monitored by the 
session.
+                * It does not have to be the owner (ctx_task) of the context 
per se.
+                */
+               if (unlikely(is_system && ctx->ctx_cpu != smp_processor_id())) {
+                       DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+                       return -EBUSY;
+               }
+               /*
+                * this can be true when not self-monitoring only in UP
+                */
+               can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
+
+               if (can_access_pmu) ia64_srlz_d();
+       }
+       expert_mode = pfm_sysctl.expert_mode; 
+
+       DPRINT(("ld=%d apmu=%d ctx_state=%d\n",
+               is_loaded,
+               can_access_pmu,
+               state));
+
+       /*
+        * on both UP and SMP, we can only read the PMD from the hardware 
register when
+        * the task is the owner of the local PMU.
+        */
+
+       for (i = 0; i < count; i++, req++) {
+
+               cnum        = req->reg_num;
+               reg_flags   = req->reg_flags;
+
+               if (unlikely(!PMD_IS_IMPL(cnum))) goto error;
+               /*
+                * we can only read the register that we use. That includes
+                * the one we explicitely initialize AND the one we want 
included
+                * in the sampling buffer (smpl_regs).
+                *
+                * Having this restriction allows optimization in the ctxsw 
routine
+                * without compromising security (leaks)
+                */
+               if (unlikely(!CTX_IS_USED_PMD(ctx, cnum))) goto error;
+
+               sval        = ctx->ctx_pmds[cnum].val;
+               lval        = ctx->ctx_pmds[cnum].lval;
+               is_counting = PMD_IS_COUNTING(cnum);
+
+               /*
+                * If the task is not the current one, then we check if the
+                * PMU state is still in the local live register due to lazy 
ctxsw.
+                * If true, then we read directly from the registers.
+                */
+               if (can_access_pmu){
+                       val = ia64_get_pmd(cnum);
+               } else {
+                       /*
+                        * context has been saved
+                        * if context is zombie, then task does not exist 
anymore.
+                        * In this case, we use the full value saved in the 
context (pfm_flush_regs()).
+                        */
+                       val = is_loaded ? thread->pmds[cnum] : 0UL;
+               }
+               rd_func = pmu_conf->pmd_desc[cnum].read_check;
+
+               if (is_counting) {
+                       /*
+                        * XXX: need to check for overflow when loaded
+                        */
+                       val &= ovfl_mask;
+                       val += sval;
+               }
+
+               /*
+                * execute read checker, if any
+                */
+               if (unlikely(expert_mode == 0 && rd_func)) {
+                       unsigned long v = val;
+                       ret = (*rd_func)(ctx->ctx_task, ctx, cnum, &v, regs);
+                       if (ret) goto error;
+                       val = v;
+                       ret = -EINVAL;
+               }
+
+               PFM_REG_RETFLAG_SET(reg_flags, 0);
+
+               DPRINT(("pmd[%u]=0x%lx\n", cnum, val));
+
+               /*
+                * update register return value, abort all if problem during 
copy.
+                * we only modify the reg_flags field. no check mode is fine 
because
+                * access has been verified upfront in sys_perfmonctl().
+                */
+               req->reg_value            = val;
+               req->reg_flags            = reg_flags;
+               req->reg_last_reset_val   = lval;
+       }
+
+       return 0;
+
+error:
+       PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
+       return ret;
+}
+
+int
+pfm_mod_write_pmcs(struct task_struct *task, void *req, unsigned int nreq, 
struct pt_regs *regs)
+{
+       pfm_context_t *ctx;
+
+       if (req == NULL) return -EINVAL;
+
+       ctx = GET_PMU_CTX();
+
+       if (ctx == NULL) return -EINVAL;
+
+       /*
+        * for now limit to current task, which is enough when calling
+        * from overflow handler
+        */
+       if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
+
+       return pfm_write_pmcs(ctx, req, nreq, regs);
+}
+EXPORT_SYMBOL(pfm_mod_write_pmcs);
+
+int
+pfm_mod_read_pmds(struct task_struct *task, void *req, unsigned int nreq, 
struct pt_regs *regs)
+{
+       pfm_context_t *ctx;
+
+       if (req == NULL) return -EINVAL;
+
+       ctx = GET_PMU_CTX();
+
+       if (ctx == NULL) return -EINVAL;
+
+       /*
+        * for now limit to current task, which is enough when calling
+        * from overflow handler
+        */
+       if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
+
+       return pfm_read_pmds(ctx, req, nreq, regs);
+}
+EXPORT_SYMBOL(pfm_mod_read_pmds);
+
+/*
+ * Only call this function when a process it trying to
+ * write the debug registers (reading is always allowed)
+ */
+int
+pfm_use_debug_registers(struct task_struct *task)
+{
+       pfm_context_t *ctx = task->thread.pfm_context;
+       unsigned long flags;
+       int ret = 0;
+
+       if (pmu_conf->use_rr_dbregs == 0) return 0;
+
+       DPRINT(("called for [%d]\n", task->pid));
+
+       /*
+        * do it only once
+        */
+       if (task->thread.flags & IA64_THREAD_DBG_VALID) return 0;
+
+       /*
+        * Even on SMP, we do not need to use an atomic here because
+        * the only way in is via ptrace() and this is possible only when the
+        * process is stopped. Even in the case where the ctxsw out is not 
totally
+        * completed by the time we come here, there is no way the 'stopped' 
process
+        * could be in the middle of fiddling with the pfm_write_ibr_dbr() 
routine.
+        * So this is always safe.
+        */
+       if (ctx && ctx->ctx_fl_using_dbreg == 1) return -1;
+
+       LOCK_PFS(flags);
+
+       /*
+        * We cannot allow setting breakpoints when system wide monitoring
+        * sessions are using the debug registers.
+        */
+       if (pfm_sessions.pfs_sys_use_dbregs> 0)
+               ret = -1;
+       else
+               pfm_sessions.pfs_ptrace_use_dbregs++;
+
+       DPRINT(("ptrace_use_dbregs=%u  sys_use_dbregs=%u by [%d] ret = %d\n",
+                 pfm_sessions.pfs_ptrace_use_dbregs,
+                 pfm_sessions.pfs_sys_use_dbregs,
+                 task->pid, ret));
+
+       UNLOCK_PFS(flags);
+
+       return ret;
+}
+
+/*
+ * This function is called for every task that exits with the
+ * IA64_THREAD_DBG_VALID set. This indicates a task which was
+ * able to use the debug registers for debugging purposes via
+ * ptrace(). Therefore we know it was not using them for
+ * perfmormance monitoring, so we only decrement the number
+ * of "ptraced" debug register users to keep the count up to date
+ */
+int
+pfm_release_debug_registers(struct task_struct *task)
+{
+       unsigned long flags;
+       int ret;
+
+       if (pmu_conf->use_rr_dbregs == 0) return 0;
+
+       LOCK_PFS(flags);
+       if (pfm_sessions.pfs_ptrace_use_dbregs == 0) {
+               printk(KERN_ERR "perfmon: invalid release for [%d] 
ptrace_use_dbregs=0\n", task->pid);
+               ret = -1;
+       }  else {
+               pfm_sessions.pfs_ptrace_use_dbregs--;
+               ret = 0;
+       }
+       UNLOCK_PFS(flags);
+
+       return ret;
+}
+
+static int
+pfm_restart(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       struct task_struct *task;
+       pfm_buffer_fmt_t *fmt;
+       pfm_ovfl_ctrl_t rst_ctrl;
+       int state, is_system;
+       int ret = 0;
+
+       state     = ctx->ctx_state;
+       fmt       = ctx->ctx_buf_fmt;
+       is_system = ctx->ctx_fl_system;
+       task      = PFM_CTX_TASK(ctx);
+
+       switch(state) {
+               case PFM_CTX_MASKED:
+                       break;
+               case PFM_CTX_LOADED: 
+                       if (CTX_HAS_SMPL(ctx) && fmt->fmt_restart_active) break;
+                       /* fall through */
+               case PFM_CTX_UNLOADED:
+               case PFM_CTX_ZOMBIE:
+                       DPRINT(("invalid state=%d\n", state));
+                       return -EBUSY;
+               default:
+                       DPRINT(("state=%d, cannot operate (no active_restart 
handler)\n", state));
+                       return -EINVAL;
+       }
+
+       /*
+        * In system wide and when the context is loaded, access can only happen
+        * when the caller is running on the CPU being monitored by the session.
+        * It does not have to be the owner (ctx_task) of the context per se.
+        */
+       if (is_system && ctx->ctx_cpu != smp_processor_id()) {
+               DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+               return -EBUSY;
+       }
+
+       /* sanity check */
+       if (unlikely(task == NULL)) {
+               printk(KERN_ERR "perfmon: [%d] pfm_restart no task\n", 
current->pid);
+               return -EINVAL;
+       }
+
+       if (task == current || is_system) {
+
+               fmt = ctx->ctx_buf_fmt;
+
+               DPRINT(("restarting self %d ovfl=0x%lx\n",
+                       task->pid,
+                       ctx->ctx_ovfl_regs[0]));
+
+               if (CTX_HAS_SMPL(ctx)) {
+
+                       prefetch(ctx->ctx_smpl_hdr);
+
+                       rst_ctrl.bits.mask_monitoring = 0;
+                       rst_ctrl.bits.reset_ovfl_pmds = 0;
+
+                       if (state == PFM_CTX_LOADED)
+                               ret = pfm_buf_fmt_restart_active(fmt, task, 
&rst_ctrl, ctx->ctx_smpl_hdr, regs);
+                       else
+                               ret = pfm_buf_fmt_restart(fmt, task, &rst_ctrl, 
ctx->ctx_smpl_hdr, regs);
+               } else {
+                       rst_ctrl.bits.mask_monitoring = 0;
+                       rst_ctrl.bits.reset_ovfl_pmds = 1;
+               }
+
+               if (ret == 0) {
+                       if (rst_ctrl.bits.reset_ovfl_pmds)
+                               pfm_reset_regs(ctx, ctx->ctx_ovfl_regs, 
PFM_PMD_LONG_RESET);
+
+                       if (rst_ctrl.bits.mask_monitoring == 0) {
+                               DPRINT(("resuming monitoring for [%d]\n", 
task->pid));
+
+                               if (state == PFM_CTX_MASKED) 
pfm_restore_monitoring(task);
+                       } else {
+                               DPRINT(("keeping monitoring stopped for 
[%d]\n", task->pid));
+
+                               // cannot use pfm_stop_monitoring(task, regs);
+                       }
+               }
+               /*
+                * clear overflowed PMD mask to remove any stale information
+                */
+               ctx->ctx_ovfl_regs[0] = 0UL;
+
+               /*
+                * back to LOADED state
+                */
+               ctx->ctx_state = PFM_CTX_LOADED;
+
+               /*
+                * XXX: not really useful for self monitoring
+                */
+               ctx->ctx_fl_can_restart = 0;
+
+               return 0;
+       }
+
+       /* 
+        * restart another task
+        */
+
+       /*
+        * When PFM_CTX_MASKED, we cannot issue a restart before the previous 
+        * one is seen by the task.
+        */
+       if (state == PFM_CTX_MASKED) {
+               if (ctx->ctx_fl_can_restart == 0) return -EINVAL;
+               /*
+                * will prevent subsequent restart before this one is
+                * seen by other task
+                */
+               ctx->ctx_fl_can_restart = 0;
+       }
+
+       /*
+        * if blocking, then post the semaphore is PFM_CTX_MASKED, i.e.
+        * the task is blocked or on its way to block. That's the normal
+        * restart path. If the monitoring is not masked, then the task
+        * can be actively monitoring and we cannot directly intervene.
+        * Therefore we use the trap mechanism to catch the task and
+        * force it to reset the buffer/reset PMDs.
+        *
+        * if non-blocking, then we ensure that the task will go into
+        * pfm_handle_work() before returning to user mode.
+        *
+        * We cannot explicitely reset another task, it MUST always
+        * be done by the task itself. This works for system wide because
+        * the tool that is controlling the session is logically doing 
+        * "self-monitoring".
+        */
+       if (CTX_OVFL_NOBLOCK(ctx) == 0 && state == PFM_CTX_MASKED) {
+               DPRINT(("unblocking [%d] \n", task->pid));
+               complete(&ctx->ctx_restart_done);
+       } else {
+               DPRINT(("[%d] armed exit trap\n", task->pid));
+
+               ctx->ctx_fl_trap_reason = PFM_TRAP_REASON_RESET;
+
+               PFM_SET_WORK_PENDING(task, 1);
+
+               pfm_set_task_notify(task);
+
+               /*
+                * XXX: send reschedule if task runs on another CPU
+                */
+       }
+       return 0;
+}
+
+static int
+pfm_debug(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       unsigned int m = *(unsigned int *)arg;
+
+       pfm_sysctl.debug = m == 0 ? 0 : 1;
+
+       printk(KERN_INFO "perfmon debugging %s (timing reset)\n", 
pfm_sysctl.debug ? "on" : "off");
+
+       if (m == 0) {
+               memset(pfm_stats, 0, sizeof(pfm_stats));
+               for(m=0; m < NR_CPUS; m++) 
pfm_stats[m].pfm_ovfl_intr_cycles_min = ~0UL;
+       }
+       return 0;
+}
+
+/*
+ * arg can be NULL and count can be zero for this function
+ */
+static int
+pfm_write_ibr_dbr(int mode, pfm_context_t *ctx, void *arg, int count, struct 
pt_regs *regs)
+{
+       struct thread_struct *thread = NULL;
+       struct task_struct *task;
+       pfarg_dbreg_t *req = (pfarg_dbreg_t *)arg;
+       unsigned long flags;
+       dbreg_t dbreg;
+       unsigned int rnum;
+       int first_time;
+       int ret = 0, state;
+       int i, can_access_pmu = 0;
+       int is_system, is_loaded;
+
+       if (pmu_conf->use_rr_dbregs == 0) return -EINVAL;
+
+       state     = ctx->ctx_state;
+       is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
+       is_system = ctx->ctx_fl_system;
+       task      = ctx->ctx_task;
+
+       if (state == PFM_CTX_ZOMBIE) return -EINVAL;
+
+       /*
+        * on both UP and SMP, we can only write to the PMC when the task is
+        * the owner of the local PMU.
+        */
+       if (is_loaded) {
+               thread = &task->thread;
+               /*
+                * In system wide and when the context is loaded, access can 
only happen
+                * when the caller is running on the CPU being monitored by the 
session.
+                * It does not have to be the owner (ctx_task) of the context 
per se.
+                */
+               if (unlikely(is_system && ctx->ctx_cpu != smp_processor_id())) {
+                       DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+                       return -EBUSY;
+               }
+               can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
+       }
+
+       /*
+        * we do not need to check for ipsr.db because we do clear ibr.x, 
dbr.r, and dbr.w
+        * ensuring that no real breakpoint can be installed via this call.
+        *
+        * IMPORTANT: regs can be NULL in this function
+        */
+
+       first_time = ctx->ctx_fl_using_dbreg == 0;
+
+       /*
+        * don't bother if we are loaded and task is being debugged
+        */
+       if (is_loaded && (thread->flags & IA64_THREAD_DBG_VALID) != 0) {
+               DPRINT(("debug registers already in use for [%d]\n", 
task->pid));
+               return -EBUSY;
+       }
+
+       /*
+        * check for debug registers in system wide mode
+        *
+        * If though a check is done in pfm_context_load(),
+        * we must repeat it here, in case the registers are
+        * written after the context is loaded
+        */
+       if (is_loaded) {
+               LOCK_PFS(flags);
+
+               if (first_time && is_system) {
+                       if (pfm_sessions.pfs_ptrace_use_dbregs)
+                               ret = -EBUSY;
+                       else
+                               pfm_sessions.pfs_sys_use_dbregs++;
+               }
+               UNLOCK_PFS(flags);
+       }
+
+       if (ret != 0) return ret;
+
+       /*
+        * mark ourself as user of the debug registers for
+        * perfmon purposes.
+        */
+       ctx->ctx_fl_using_dbreg = 1;
+
+       /*
+        * clear hardware registers to make sure we don't
+        * pick up stale state.
+        *
+        * for a system wide session, we do not use
+        * thread.dbr, thread.ibr because this process
+        * never leaves the current CPU and the state
+        * is shared by all processes running on it
+        */
+       if (first_time && can_access_pmu) {
+               DPRINT(("[%d] clearing ibrs, dbrs\n", task->pid));
+               for (i=0; i < pmu_conf->num_ibrs; i++) {
+                       ia64_set_ibr(i, 0UL);
+                       ia64_dv_serialize_instruction();
+               }
+               ia64_srlz_i();
+               for (i=0; i < pmu_conf->num_dbrs; i++) {
+                       ia64_set_dbr(i, 0UL);
+                       ia64_dv_serialize_data();
+               }
+               ia64_srlz_d();
+       }
+
+       /*
+        * Now install the values into the registers
+        */
+       for (i = 0; i < count; i++, req++) {
+
+               rnum      = req->dbreg_num;
+               dbreg.val = req->dbreg_value;
+
+               ret = -EINVAL;
+
+               if ((mode == PFM_CODE_RR && rnum >= PFM_NUM_IBRS) || ((mode == 
PFM_DATA_RR) && rnum >= PFM_NUM_DBRS)) {
+                       DPRINT(("invalid register %u val=0x%lx mode=%d i=%d 
count=%d\n",
+                                 rnum, dbreg.val, mode, i, count));
+
+                       goto abort_mission;
+               }
+
+               /*
+                * make sure we do not install enabled breakpoint
+                */
+               if (rnum & 0x1) {
+                       if (mode == PFM_CODE_RR)
+                               dbreg.ibr.ibr_x = 0;
+                       else
+                               dbreg.dbr.dbr_r = dbreg.dbr.dbr_w = 0;
+               }
+
+               PFM_REG_RETFLAG_SET(req->dbreg_flags, 0);
+
+               /*
+                * Debug registers, just like PMC, can only be modified
+                * by a kernel call. Moreover, perfmon() access to those
+                * registers are centralized in this routine. The hardware
+                * does not modify the value of these registers, therefore,
+                * if we save them as they are written, we can avoid having
+                * to save them on context switch out. This is made possible
+                * by the fact that when perfmon uses debug registers, ptrace()
+                * won't be able to modify them concurrently.
+                */
+               if (mode == PFM_CODE_RR) {
+                       CTX_USED_IBR(ctx, rnum);
+
+                       if (can_access_pmu) {
+                               ia64_set_ibr(rnum, dbreg.val);
+                               ia64_dv_serialize_instruction();
+                       }
+
+                       ctx->ctx_ibrs[rnum] = dbreg.val;
+
+                       DPRINT(("write ibr%u=0x%lx used_ibrs=0x%x ld=%d 
apmu=%d\n",
+                               rnum, dbreg.val, ctx->ctx_used_ibrs[0], 
is_loaded, can_access_pmu));
+               } else {
+                       CTX_USED_DBR(ctx, rnum);
+
+                       if (can_access_pmu) {
+                               ia64_set_dbr(rnum, dbreg.val);
+                               ia64_dv_serialize_data();
+                       }
+                       ctx->ctx_dbrs[rnum] = dbreg.val;
+
+                       DPRINT(("write dbr%u=0x%lx used_dbrs=0x%x ld=%d 
apmu=%d\n",
+                               rnum, dbreg.val, ctx->ctx_used_dbrs[0], 
is_loaded, can_access_pmu));
+               }
+       }
+
+       return 0;
+
+abort_mission:
+       /*
+        * in case it was our first attempt, we undo the global modifications
+        */
+       if (first_time) {
+               LOCK_PFS(flags);
+               if (ctx->ctx_fl_system) {
+                       pfm_sessions.pfs_sys_use_dbregs--;
+               }
+               UNLOCK_PFS(flags);
+               ctx->ctx_fl_using_dbreg = 0;
+       }
+       /*
+        * install error return flag
+        */
+       PFM_REG_RETFLAG_SET(req->dbreg_flags, PFM_REG_RETFL_EINVAL);
+
+       return ret;
+}
+
+static int
+pfm_write_ibrs(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       return pfm_write_ibr_dbr(PFM_CODE_RR, ctx, arg, count, regs);
+}
+
+static int
+pfm_write_dbrs(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       return pfm_write_ibr_dbr(PFM_DATA_RR, ctx, arg, count, regs);
+}
+
+int
+pfm_mod_write_ibrs(struct task_struct *task, void *req, unsigned int nreq, 
struct pt_regs *regs)
+{
+       pfm_context_t *ctx;
+
+       if (req == NULL) return -EINVAL;
+
+       ctx = GET_PMU_CTX();
+
+       if (ctx == NULL) return -EINVAL;
+
+       /*
+        * for now limit to current task, which is enough when calling
+        * from overflow handler
+        */
+       if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
+
+       return pfm_write_ibrs(ctx, req, nreq, regs);
+}
+EXPORT_SYMBOL(pfm_mod_write_ibrs);
+
+int
+pfm_mod_write_dbrs(struct task_struct *task, void *req, unsigned int nreq, 
struct pt_regs *regs)
+{
+       pfm_context_t *ctx;
+
+       if (req == NULL) return -EINVAL;
+
+       ctx = GET_PMU_CTX();
+
+       if (ctx == NULL) return -EINVAL;
+
+       /*
+        * for now limit to current task, which is enough when calling
+        * from overflow handler
+        */
+       if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
+
+       return pfm_write_dbrs(ctx, req, nreq, regs);
+}
+EXPORT_SYMBOL(pfm_mod_write_dbrs);
+
+
+static int
+pfm_get_features(pfm_context_t *ctx, void *arg, int count, struct pt_regs 
*regs)
+{
+       pfarg_features_t *req = (pfarg_features_t *)arg;
+
+       req->ft_version = PFM_VERSION;
+       return 0;
+}
+
+static int
+pfm_stop(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       struct pt_regs *tregs;
+       struct task_struct *task = PFM_CTX_TASK(ctx);
+       int state, is_system;
+
+       state     = ctx->ctx_state;
+       is_system = ctx->ctx_fl_system;
+
+       /*
+        * context must be attached to issue the stop command (includes 
LOADED,MASKED,ZOMBIE)
+        */
+       if (state == PFM_CTX_UNLOADED) return -EINVAL;
+
+       /*
+        * In system wide and when the context is loaded, access can only happen
+        * when the caller is running on the CPU being monitored by the session.
+        * It does not have to be the owner (ctx_task) of the context per se.
+        */
+       if (is_system && ctx->ctx_cpu != smp_processor_id()) {
+               DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+               return -EBUSY;
+       }
+       DPRINT(("task [%d] ctx_state=%d is_system=%d\n",
+               PFM_CTX_TASK(ctx)->pid,
+               state,
+               is_system));
+       /*
+        * in system mode, we need to update the PMU directly
+        * and the user level state of the caller, which may not
+        * necessarily be the creator of the context.
+        */
+       if (is_system) {
+               /*
+                * Update local PMU first
+                *
+                * disable dcr pp
+                */
+               ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) & 
~IA64_DCR_PP);
+               ia64_srlz_i();
+
+               /*
+                * update local cpuinfo
+                */
+               PFM_CPUINFO_CLEAR(PFM_CPUINFO_DCR_PP);
+
+               /*
+                * stop monitoring, does srlz.i
+                */
+               pfm_clear_psr_pp();
+
+               /*
+                * stop monitoring in the caller
+                */
+               ia64_psr(regs)->pp = 0;
+
+               return 0;
+       }
+       /*
+        * per-task mode
+        */
+
+       if (task == current) {
+               /* stop monitoring  at kernel level */
+               pfm_clear_psr_up();
+
+               /*
+                * stop monitoring at the user level
+                */
+               ia64_psr(regs)->up = 0;
+       } else {
+               tregs = task_pt_regs(task);
+
+               /*
+                * stop monitoring at the user level
+                */
+               ia64_psr(tregs)->up = 0;
+
+               /*
+                * monitoring disabled in kernel at next reschedule
+                */
+               ctx->ctx_saved_psr_up = 0;
+               DPRINT(("task=[%d]\n", task->pid));
+       }
+       return 0;
+}
+
+
+static int
+pfm_start(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
+{
+       struct pt_regs *tregs;
+       int state, is_system;
+
+       state     = ctx->ctx_state;
+       is_system = ctx->ctx_fl_system;
+
+       if (state != PFM_CTX_LOADED) return -EINVAL;
+
+       /*
+        * In system wide and when the context is loaded, access can only happen
+        * when the caller is running on the CPU being monitored by the session.
+        * It does not have to be the owner (ctx_task) of the context per se.
+        */
+       if (is_system && ctx->ctx_cpu != smp_processor_id()) {
+               DPRINT(("should be running on CPU%d\n", ctx->ctx_cpu));
+               return -EBUSY;
+       }
+
+       /*
+        * in system mode, we need to update the PMU directly
+        * and the user level state of the caller, which may not
+        * necessarily be the creator of the context.
+        */
+       if (is_system) {
+
+               /*
+                * set user level psr.pp for the caller
+                */
+               ia64_psr(regs)->pp = 1;
+
+               /*
+                * now update the local PMU and cpuinfo
+                */
+               PFM_CPUINFO_SET(PFM_CPUINFO_DCR_PP);
+
+               /*
+                * start monitoring at kernel level
+                */
+               pfm_set_psr_pp();
+
+               /* enable dcr pp */
+               ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) | 
IA64_DCR_PP);
+               ia64_srlz_i();
+
+               return 0;
+       }
+
+       /*
+        * per-process mode
+        */
+
+       if (ctx->ctx_task == current) {
+
+               /* start monitoring at kernel level */
+               pfm_set_psr_up();
+
+               /*
+                * activate monitoring at user level
+                */
+               ia64_psr(regs)->up = 1;
+
+       } else {
+               tregs = task_pt_regs(ctx->ctx_task);
+
+               /*
+                * start monitoring at the kernel level the next
+                * time the task is scheduled
+                */
+               ctx->ctx_saved_psr_up = IA64_PSR_UP;
+
+               /*
+                * activate monitoring at user level
+                */
+               ia64_psr(tregs)->up = 1;
+       }
+       return 0;
+}
+
+static int
+pfm_get_pmc_reset(pfm_context_t *ctx, void *arg, int count, struct pt_regs 
*regs)
+{
+       pfarg_reg_t *req = (pfarg_reg_t *)arg;
+       unsigned int cnum;
+       int i;
+       int ret = -EINVAL;
+
+       for (i = 0; i < count; i++, req++) {
+
+               cnum = req->reg_num;
+
+               if (!PMC_IS_IMPL(cnum)) goto abort_mission;
+
+               req->reg_value = PMC_DFL_VAL(cnum);
+
+               PFM_REG_RETFLAG_SET(req->reg_flags, 0);
+
+               DPRINT(("pmc_reset_val pmc[%u]=0x%lx\n", cnum, req->reg_value));
+       }
+       return 0;
+
+abort_mission:
+       PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
+       return ret;
+}
+
+static int
+pfm_check_task_exist(pfm_context_t *ctx)
+{
+       struct task_struct *g, *t;
+       int ret = -ESRCH;
+
+       read_lock(&tasklist_lock);
+
+       do_each_thread (g, t) {
+               if (t->thread.pfm_context == ctx) {
+                       ret = 0;
+                       break;
+               }
+       } while_each_thread (g, t);
+
+       read_unlock(&tasklist_lock);
+
+       DPRINT(("pfm_check_task_exist: ret=%d ctx=%p\n", ret, ctx));
+
+       return ret;
+}
+
+static int
+pfm_context_load(pfm_context_t *ctx, void *arg, int count, struct pt_regs 
*regs)
+{
+       struct task_struct *task;
+       struct thread_struct *thread;
+       struct pfm_context_t *old;
+       unsigned long flags;
+#ifndef CONFIG_SMP
+       struct task_struct *owner_task = NULL;
+#endif
+       pfarg_load_t *req = (pfarg_load_t *)arg;
+       unsigned long *pmcs_source, *pmds_source;
+       int the_cpu;
+       int ret = 0;
+       int state, is_system, set_dbregs = 0;
+
+       state     = ctx->ctx_state;
+       is_system = ctx->ctx_fl_system;
+       /*
+        * can only load from unloaded or terminated state
+        */
+       if (state != PFM_CTX_UNLOADED) {
+               DPRINT(("cannot load to [%d], invalid ctx_state=%d\n",
+                       req->load_pid,
+                       ctx->ctx_state));
+               return -EBUSY;
+       }
+
+       DPRINT(("load_pid [%d] using_dbreg=%d\n", req->load_pid, 
ctx->ctx_fl_using_dbreg));
+
+       if (CTX_OVFL_NOBLOCK(ctx) == 0 && req->load_pid == current->pid) {
+               DPRINT(("cannot use blocking mode on self\n"));
+               return -EINVAL;
+       }
+
+       ret = pfm_get_task(ctx, req->load_pid, &task);
+       if (ret) {
+               DPRINT(("load_pid [%d] get_task=%d\n", req->load_pid, ret));
+               return ret;
+       }
+
+       ret = -EINVAL;
+
+       /*
+        * system wide is self monitoring only
+        */
+       if (is_system && task != current) {
+               DPRINT(("system wide is self monitoring only load_pid=%d\n",
+                       req->load_pid));
+               goto error;
+       }
+
+       thread = &task->thread;
+
+       ret = 0;
+       /*
+        * cannot load a context which is using range restrictions,
+        * into a task that is being debugged.
+        */
+       if (ctx->ctx_fl_using_dbreg) {
+               if (thread->flags & IA64_THREAD_DBG_VALID) {
+                       ret = -EBUSY;
+                       DPRINT(("load_pid [%d] task is debugged, cannot load 
range restrictions\n", req->load_pid));
+                       goto error;
+               }
+               LOCK_PFS(flags);
+
+               if (is_system) {
+                       if (pfm_sessions.pfs_ptrace_use_dbregs) {
+                               DPRINT(("cannot load [%d] dbregs in use\n", 
task->pid));
+                               ret = -EBUSY;
+                       } else {
+                               pfm_sessions.pfs_sys_use_dbregs++;
+                               DPRINT(("load [%d] increased 
sys_use_dbreg=%u\n", task->pid, pfm_sessions.pfs_sys_use_dbregs));
+                               set_dbregs = 1;
+                       }
+               }
+
+               UNLOCK_PFS(flags);
+
+               if (ret) goto error;
+       }
+
+       /*
+        * SMP system-wide monitoring implies self-monitoring.
+        *
+        * The programming model expects the task to
+        * be pinned on a CPU throughout the session.
+        * Here we take note of the current CPU at the
+        * time the context is loaded. No call from
+        * another CPU will be allowed.
+        *
+        * The pinning via shed_setaffinity()
+        * must be done by the calling task prior
+        * to this call.
+        *
+        * systemwide: keep track of CPU this session is supposed to run on
+        */
+       the_cpu = ctx->ctx_cpu = smp_processor_id();
+
+       ret = -EBUSY;
+       /*
+        * now reserve the session
+        */
+       ret = pfm_reserve_session(current, is_system, the_cpu);
+       if (ret) goto error;
+
+       /*
+        * task is necessarily stopped at this point.
+        *
+        * If the previous context was zombie, then it got removed in
+        * pfm_save_regs(). Therefore we should not see it here.
+        * If we see a context, then this is an active context
+        *
+        * XXX: needs to be atomic
+        */
+       DPRINT(("before cmpxchg() old_ctx=%p new_ctx=%p\n",
+               thread->pfm_context, ctx));
+
+       ret = -EBUSY;
+       old = ia64_cmpxchg(acq, &thread->pfm_context, NULL, ctx, 
sizeof(pfm_context_t *));
+       if (old != NULL) {
+               DPRINT(("load_pid [%d] already has a context\n", 
req->load_pid));
+               goto error_unres;
+       }
+
+       pfm_reset_msgq(ctx);
+
+       ctx->ctx_state = PFM_CTX_LOADED;
+
+       /*
+        * link context to task
+        */
+       ctx->ctx_task = task;
+
+       if (is_system) {
+               /*
+                * we load as stopped
+                */
+               PFM_CPUINFO_SET(PFM_CPUINFO_SYST_WIDE);
+               PFM_CPUINFO_CLEAR(PFM_CPUINFO_DCR_PP);
+
+               if (ctx->ctx_fl_excl_idle) 
PFM_CPUINFO_SET(PFM_CPUINFO_EXCL_IDLE);
+       } else {
+               thread->flags |= IA64_THREAD_PM_VALID;
+       }
+
+       /*
+        * propagate into thread-state
+        */
+       pfm_copy_pmds(task, ctx);
+       pfm_copy_pmcs(task, ctx);
+
+       pmcs_source = thread->pmcs;
+       pmds_source = thread->pmds;
+
+       /*
+        * always the case for system-wide
+        */
+       if (task == current) {
+
+               if (is_system == 0) {
+
+                       /* allow user level control */
+                       ia64_psr(regs)->sp = 0;
+                       DPRINT(("clearing psr.sp for [%d]\n", task->pid));
+
+                       SET_LAST_CPU(ctx, smp_processor_id());
+                       INC_ACTIVATION();
+                       SET_ACTIVATION(ctx);
+#ifndef CONFIG_SMP
+                       /*
+                        * push the other task out, if any
+                        */
+                       owner_task = GET_PMU_OWNER();
+                       if (owner_task) pfm_lazy_save_regs(owner_task);
+#endif
+               }
+               /*
+                * load all PMD from ctx to PMU (as opposed to thread state)
+                * restore all PMC from ctx to PMU
+                */
+               pfm_restore_pmds(pmds_source, ctx->ctx_all_pmds[0]);
+               pfm_restore_pmcs(pmcs_source, ctx->ctx_all_pmcs[0]);
+
+               ctx->ctx_reload_pmcs[0] = 0UL;
+               ctx->ctx_reload_pmds[0] = 0UL;
+
+               /*
+                * guaranteed safe by earlier check against DBG_VALID
+                */
+               if (ctx->ctx_fl_using_dbreg) {
+                       pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
+                       pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
+               }
+               /*
+                * set new ownership
+                */
+               SET_PMU_OWNER(task, ctx);
+
+               DPRINT(("context loaded on PMU for [%d]\n", task->pid));
+       } else {
+               /*
+                * when not current, task MUST be stopped, so this is safe
+                */
+               regs = task_pt_regs(task);
+
+               /* force a full reload */
+               ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
+               SET_LAST_CPU(ctx, -1);
+
+               /* initial saved psr (stopped) */
+               ctx->ctx_saved_psr_up = 0UL;
+               ia64_psr(regs)->up = ia64_psr(regs)->pp = 0;
+       }
+
+       ret = 0;
+
+error_unres:
+       if (ret) pfm_unreserve_session(ctx, ctx->ctx_fl_system, the_cpu);
+error:
+       /*
+        * we must undo the dbregs setting (for system-wide)
+        */
+       if (ret && set_dbregs) {
+               LOCK_PFS(flags);
+               pfm_sessions.pfs_sys_use_dbregs--;
+               UNLOCK_PFS(flags);
+       }
+       /*
+        * release task, there is now a link with the context
+        */
+       if (is_system == 0 && task != current) {
+               pfm_put_task(task);
+
+               if (ret == 0) {
+                       ret = pfm_check_task_exist(ctx);
+                       if (ret) {
+                               ctx->ctx_state = PFM_CTX_UNLOADED;
+                               ctx->ctx_task  = NULL;
+                       }
+               }
+       }
+       return ret;
+}
+
+/*
+ * in this function, we do not need to increase the use count
+ * for the task via get_task_struct(), because we hold the
+ * context lock. If the task were to disappear while having
+ * a context attached, it would go through pfm_exit_thread()
+ * which also grabs the context lock  and would therefore be blocked
+ * until we are here.
+ */
+static void pfm_flush_pmds(struct task_struct *, pfm_context_t *ctx);
+
+static int
+pfm_context_unload(pfm_context_t *ctx, void *arg, int count, struct pt_regs 
*regs)
+{
+       struct task_struct *task = PFM_CTX_TASK(ctx);
+       struct pt_regs *tregs;
+       int prev_state, is_system;
+       int ret;
+
+       DPRINT(("ctx_state=%d task [%d]\n", ctx->ctx_state, task ? task->pid : 
-1));
+
+       prev_state = ctx->ctx_state;
+       is_system  = ctx->ctx_fl_system;
+
+       /*
+        * unload only when necessary
+        */
+       if (prev_state == PFM_CTX_UNLOADED) {
+               DPRINT(("ctx_state=%d, nothing to do\n", prev_state));
+               return 0;
+       }
+
+       /*
+        * clear psr and dcr bits
+        */
+       ret = pfm_stop(ctx, NULL, 0, regs);
+       if (ret) return ret;
+
+       ctx->ctx_state = PFM_CTX_UNLOADED;
+
+       /*
+        * in system mode, we need to update the PMU directly
+        * and the user level state of the caller, which may not
+        * necessarily be the creator of the context.
+        */
+       if (is_system) {
+
+               /*
+                * Update cpuinfo
+                *
+                * local PMU is taken care of in pfm_stop()
+                */
+               PFM_CPUINFO_CLEAR(PFM_CPUINFO_SYST_WIDE);
+               PFM_CPUINFO_CLEAR(PFM_CPUINFO_EXCL_IDLE);
+
+               /*
+                * save PMDs in context
+                * release ownership
+                */
+               pfm_flush_pmds(current, ctx);
+
+               /*
+                * at this point we are done with the PMU
+                * so we can unreserve the resource.
+                */
+               if (prev_state != PFM_CTX_ZOMBIE) 
+                       pfm_unreserve_session(ctx, 1 , ctx->ctx_cpu);
+
+               /*
+                * disconnect context from task
+                */
+               task->thread.pfm_context = NULL;
+               /*
+                * disconnect task from context
+                */
+               ctx->ctx_task = NULL;
+
+               /*
+                * There is nothing more to cleanup here.
+                */
+               return 0;
+       }
+
+       /*
+        * per-task mode
+        */
+       tregs = task == current ? regs : task_pt_regs(task);
+
+       if (task == current) {
+               /*
+                * cancel user level control
+                */
+               ia64_psr(regs)->sp = 1;
+
+               DPRINT(("setting psr.sp for [%d]\n", task->pid));
+       }
+       /*
+        * save PMDs to context
+        * release ownership
+        */
+       pfm_flush_pmds(task, ctx);
+
+       /*
+        * at this point we are done with the PMU
+        * so we can unreserve the resource.
+        *
+        * when state was ZOMBIE, we have already unreserved.
+        */
+       if (prev_state != PFM_CTX_ZOMBIE) 
+               pfm_unreserve_session(ctx, 0 , ctx->ctx_cpu);
+
+       /*
+        * reset activation counter and psr
+        */
+       ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
+       SET_LAST_CPU(ctx, -1);
+
+       /*
+        * PMU state will not be restored
+        */
+       task->thread.flags &= ~IA64_THREAD_PM_VALID;
+
+       /*
+        * break links between context and task
+        */
+       task->thread.pfm_context  = NULL;
+       ctx->ctx_task             = NULL;
+
+       PFM_SET_WORK_PENDING(task, 0);
+
+       ctx->ctx_fl_trap_reason  = PFM_TRAP_REASON_NONE;
+       ctx->ctx_fl_can_restart  = 0;
+       ctx->ctx_fl_going_zombie = 0;
+
+       DPRINT(("disconnected [%d] from context\n", task->pid));
+
+       return 0;
+}
+
+
+/*
+ * called only from exit_thread(): task == current
+ * we come here only if current has a context attached (loaded or masked)
+ */
+void
+pfm_exit_thread(struct task_struct *task)
+{
+       pfm_context_t *ctx;
+       unsigned long flags;
+       struct pt_regs *regs = task_pt_regs(task);
+       int ret, state;
+       int free_ok = 0;
+
+       ctx = PFM_GET_CTX(task);
+
+       PROTECT_CTX(ctx, flags);
+
+       DPRINT(("state=%d task [%d]\n", ctx->ctx_state, task->pid));
+
+       state = ctx->ctx_state;
+       switch(state) {
+               case PFM_CTX_UNLOADED:
+                       /*
+                        * only comes to thios function if pfm_context is not 
NULL, i.e., cannot
+                        * be in unloaded state
+                        */
+                       printk(KERN_ERR "perfmon: pfm_exit_thread [%d] ctx 
unloaded\n", task->pid);
+                       break;
+               case PFM_CTX_LOADED:
+               case PFM_CTX_MASKED:
+                       ret = pfm_context_unload(ctx, NULL, 0, regs);
+                       if (ret) {
+                               printk(KERN_ERR "perfmon: pfm_exit_thread [%d] 
state=%d unload failed %d\n", task->pid, state, ret);
+                       }
+                       DPRINT(("ctx unloaded for current state was %d\n", 
state));
+
+                       pfm_end_notify_user(ctx);
+                       break;
+               case PFM_CTX_ZOMBIE:
+                       ret = pfm_context_unload(ctx, NULL, 0, regs);
+                       if (ret) {
+                               printk(KERN_ERR "perfmon: pfm_exit_thread [%d] 
state=%d unload failed %d\n", task->pid, state, ret);
+                       }
+                       free_ok = 1;
+                       break;
+               default:
+                       printk(KERN_ERR "perfmon: pfm_exit_thread [%d] 
unexpected state=%d\n", task->pid, state);
+                       break;
+       }
+       UNPROTECT_CTX(ctx, flags);
+
+       { u64 psr = pfm_get_psr();
+         BUG_ON(psr & (IA64_PSR_UP|IA64_PSR_PP));
+         BUG_ON(GET_PMU_OWNER());
+         BUG_ON(ia64_psr(regs)->up);
+         BUG_ON(ia64_psr(regs)->pp);
+       }
+
+       /*
+        * All memory free operations (especially for vmalloc'ed memory)
+        * MUST be done with interrupts ENABLED.
+        */
+       if (free_ok) pfm_context_free(ctx);
+}
+
+/*
+ * functions MUST be listed in the increasing order of their index (see 
permfon.h)
+ */
+#define PFM_CMD(name, flags, arg_count, arg_type, getsz) { name, #name, flags, 
arg_count, sizeof(arg_type), getsz }
+#define PFM_CMD_S(name, flags) { name, #name, flags, 0, 0, NULL }
+#define PFM_CMD_PCLRWS (PFM_CMD_FD|PFM_CMD_ARG_RW|PFM_CMD_STOP)
+#define PFM_CMD_PCLRW  (PFM_CMD_FD|PFM_CMD_ARG_RW)
+#define PFM_CMD_NONE   { NULL, "no-cmd", 0, 0, 0, NULL}
+
+static pfm_cmd_desc_t pfm_cmd_tab[]={
+/* 0  */PFM_CMD_NONE,
+/* 1  */PFM_CMD(pfm_write_pmcs, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_reg_t, 
NULL),
+/* 2  */PFM_CMD(pfm_write_pmds, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_reg_t, 
NULL),
+/* 3  */PFM_CMD(pfm_read_pmds, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_reg_t, 
NULL),
+/* 4  */PFM_CMD_S(pfm_stop, PFM_CMD_PCLRWS),
+/* 5  */PFM_CMD_S(pfm_start, PFM_CMD_PCLRWS),
+/* 6  */PFM_CMD_NONE,
+/* 7  */PFM_CMD_NONE,
+/* 8  */PFM_CMD(pfm_context_create, PFM_CMD_ARG_RW, 1, pfarg_context_t, 
pfm_ctx_getsize),
+/* 9  */PFM_CMD_NONE,
+/* 10 */PFM_CMD_S(pfm_restart, PFM_CMD_PCLRW),
+/* 11 */PFM_CMD_NONE,
+/* 12 */PFM_CMD(pfm_get_features, PFM_CMD_ARG_RW, 1, pfarg_features_t, NULL),
+/* 13 */PFM_CMD(pfm_debug, 0, 1, unsigned int, NULL),
+/* 14 */PFM_CMD_NONE,
+/* 15 */PFM_CMD(pfm_get_pmc_reset, PFM_CMD_ARG_RW, PFM_CMD_ARG_MANY, 
pfarg_reg_t, NULL),
+/* 16 */PFM_CMD(pfm_context_load, PFM_CMD_PCLRWS, 1, pfarg_load_t, NULL),
+/* 17 */PFM_CMD_S(pfm_context_unload, PFM_CMD_PCLRWS),
+/* 18 */PFM_CMD_NONE,
+/* 19 */PFM_CMD_NONE,
+/* 20 */PFM_CMD_NONE,
+/* 21 */PFM_CMD_NONE,
+/* 22 */PFM_CMD_NONE,
+/* 23 */PFM_CMD_NONE,
+/* 24 */PFM_CMD_NONE,
+/* 25 */PFM_CMD_NONE,
+/* 26 */PFM_CMD_NONE,
+/* 27 */PFM_CMD_NONE,
+/* 28 */PFM_CMD_NONE,
+/* 29 */PFM_CMD_NONE,
+/* 30 */PFM_CMD_NONE,
+/* 31 */PFM_CMD_NONE,
+/* 32 */PFM_CMD(pfm_write_ibrs, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, 
pfarg_dbreg_t, NULL),
+/* 33 */PFM_CMD(pfm_write_dbrs, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, 
pfarg_dbreg_t, NULL)
+};
+#define PFM_CMD_COUNT  (sizeof(pfm_cmd_tab)/sizeof(pfm_cmd_desc_t))
+
+static int
+pfm_check_task_state(pfm_context_t *ctx, int cmd, unsigned long flags)
+{
+       struct task_struct *task;
+       int state, old_state;
+
+recheck:
+       state = ctx->ctx_state;
+       task  = ctx->ctx_task;
+
+       if (task == NULL) {
+               DPRINT(("context %d no task, state=%d\n", ctx->ctx_fd, state));
+               return 0;
+       }
+
+       DPRINT(("context %d state=%d [%d] task_state=%ld must_stop=%d\n",
+               ctx->ctx_fd,
+               state,
+               task->pid,
+               task->state, PFM_CMD_STOPPED(cmd)));
+
+       /*
+        * self-monitoring always ok.
+        *
+        * for system-wide the caller can either be the creator of the
+        * context (to one to which the context is attached to) OR
+        * a task running on the same CPU as the session.
+        */
+       if (task == current || ctx->ctx_fl_system) return 0;
+
+       /*
+        * we are monitoring another thread
+        */
+       switch(state) {
+               case PFM_CTX_UNLOADED:
+                       /*
+                        * if context is UNLOADED we are safe to go
+                        */
+                       return 0;
+               case PFM_CTX_ZOMBIE:
+                       /*
+                        * no command can operate on a zombie context
+                        */
+                       DPRINT(("cmd %d state zombie cannot operate on 
context\n", cmd));
+                       return -EINVAL;
+               case PFM_CTX_MASKED:
+                       /*
+                        * PMU state has been saved to software even though
+                        * the thread may still be running.
+                        */
+                       if (cmd != PFM_UNLOAD_CONTEXT) return 0;
+       }
+
+       /*
+        * context is LOADED or MASKED. Some commands may need to have 
+        * the task stopped.
+        *
+        * We could lift this restriction for UP but it would mean that
+        * the user has no guarantee the task would not run between
+        * two successive calls to perfmonctl(). That's probably OK.
+        * If this user wants to ensure the task does not run, then
+        * the task must be stopped.
+        */
+       if (PFM_CMD_STOPPED(cmd)) {
+               if ((task->state != TASK_STOPPED) && (task->state != 
TASK_TRACED)) {
+                       DPRINT(("[%d] task not in stopped state\n", task->pid));
+                       return -EBUSY;
+               }
+               /*
+                * task is now stopped, wait for ctxsw out
+                *
+                * This is an interesting point in the code.
+                * We need to unprotect the context because
+                * the pfm_save_regs() routines needs to grab
+                * the same lock. There are danger in doing
+                * this because it leaves a window open for
+                * another task to get access to the context
+                * and possibly change its state. The one thing
+                * that is not possible is for the context to disappear
+                * because we are protected by the VFS layer, i.e.,
+                * get_fd()/put_fd().
+                */
+               old_state = state;
+
+               UNPROTECT_CTX(ctx, flags);
+
+               wait_task_inactive(task);
+
+               PROTECT_CTX(ctx, flags);
+
+               /*
+                * we must recheck to verify if state has changed
+                */
+               if (ctx->ctx_state != old_state) {
+                       DPRINT(("old_state=%d new_state=%d\n", old_state, 
ctx->ctx_state));
+                       goto recheck;
+               }
+       }
+       return 0;
+}
+
+/*
+ * system-call entry point (must return long)
+ */
+asmlinkage long
+sys_perfmonctl (int fd, int cmd, void __user *arg, int count)
+{
+       struct file *file = NULL;
+       pfm_context_t *ctx = NULL;
+       unsigned long flags = 0UL;
+       void *args_k = NULL;
+       long ret; /* will expand int return types */
+       size_t base_sz, sz, xtra_sz = 0;
+       int narg, completed_args = 0, call_made = 0, cmd_flags;
+       int (*func)(pfm_context_t *ctx, void *arg, int count, struct pt_regs 
*regs);
+       int (*getsize)(void *arg, size_t *sz);
+#define PFM_MAX_ARGSIZE        4096
+
+       /*
+        * reject any call if perfmon was disabled at initialization
+        */
+       if (unlikely(pmu_conf == NULL)) return -ENOSYS;
+
+       if (unlikely(cmd < 0 || cmd >= PFM_CMD_COUNT)) {
+               DPRINT(("invalid cmd=%d\n", cmd));
+               return -EINVAL;
+       }
+
+       func      = pfm_cmd_tab[cmd].cmd_func;
+       narg      = pfm_cmd_tab[cmd].cmd_narg;
+       base_sz   = pfm_cmd_tab[cmd].cmd_argsize;
+       getsize   = pfm_cmd_tab[cmd].cmd_getsize;
+       cmd_flags = pfm_cmd_tab[cmd].cmd_flags;
+
+       if (unlikely(func == NULL)) {
+               DPRINT(("invalid cmd=%d\n", cmd));
+               return -EINVAL;
+       }
+
+       DPRINT(("cmd=%s idx=%d narg=0x%x argsz=%lu count=%d\n",
+               PFM_CMD_NAME(cmd),
+               cmd,
+               narg,
+               base_sz,
+               count));
+
+       /*
+        * check if number of arguments matches what the command expects
+        */
+       if (unlikely((narg == PFM_CMD_ARG_MANY && count <= 0) || (narg > 0 && 
narg != count)))
+               return -EINVAL;
+
+restart_args:
+       sz = xtra_sz + base_sz*count;
+       /*
+        * limit abuse to min page size
+        */
+       if (unlikely(sz > PFM_MAX_ARGSIZE)) {
+               printk(KERN_ERR "perfmon: [%d] argument too big %lu\n", 
current->pid, sz);
+               return -E2BIG;
+       }
+
+       /*
+        * allocate default-sized argument buffer
+        */
+       if (likely(count && args_k == NULL)) {
+               args_k = kmalloc(PFM_MAX_ARGSIZE, GFP_KERNEL);
+               if (args_k == NULL) return -ENOMEM;
+       }
+
+       ret = -EFAULT;
+
+       /*
+        * copy arguments
+        *
+        * assume sz = 0 for command without parameters
+        */
+       if (sz && copy_from_user(args_k, arg, sz)) {
+               DPRINT(("cannot copy_from_user %lu bytes @%p\n", sz, arg));
+               goto error_args;
+       }
+
+       /*
+        * check if command supports extra parameters
+        */
+       if (completed_args == 0 && getsize) {
+               /*
+                * get extra parameters size (based on main argument)
+                */
+               ret = (*getsize)(args_k, &xtra_sz);
+               if (ret) goto error_args;
+
+               completed_args = 1;
+
+               DPRINT(("restart_args sz=%lu xtra_sz=%lu\n", sz, xtra_sz));
+
+               /* retry if necessary */
+               if (likely(xtra_sz)) goto restart_args;
+       }
+
+       if (unlikely((cmd_flags & PFM_CMD_FD) == 0)) goto skip_fd;
+
+       ret = -EBADF;
+
+       file = fget(fd);
+       if (unlikely(file == NULL)) {
+               DPRINT(("invalid fd %d\n", fd));
+               goto error_args;
+       }
+       if (unlikely(PFM_IS_FILE(file) == 0)) {
+               DPRINT(("fd %d not related to perfmon\n", fd));
+               goto error_args;
+       }
+
+       ctx = (pfm_context_t *)file->private_data;
+       if (unlikely(ctx == NULL)) {
+               DPRINT(("no context for fd %d\n", fd));
+               goto error_args;
+       }
+       prefetch(&ctx->ctx_state);
+
+       PROTECT_CTX(ctx, flags);
+
+       /*
+        * check task is stopped
+        */
+       ret = pfm_check_task_state(ctx, cmd, flags);
+       if (unlikely(ret)) goto abort_locked;
+
+skip_fd:
+       ret = (*func)(ctx, args_k, count, task_pt_regs(current));
+
+       call_made = 1;
+
+abort_locked:
+       if (likely(ctx)) {
+               DPRINT(("context unlocked\n"));
+               UNPROTECT_CTX(ctx, flags);
+       }
+
+       /* copy argument back to user, if needed */
+       if (call_made && PFM_CMD_RW_ARG(cmd) && copy_to_user(arg, args_k, 
base_sz*count)) ret = -EFAULT;
+
+error_args:
+       if (file)
+               fput(file);
+
+       kfree(args_k);
+
+       DPRINT(("cmd=%s ret=%ld\n", PFM_CMD_NAME(cmd), ret));
+
+       return ret;
+}
+
+static void
+pfm_resume_after_ovfl(pfm_context_t *ctx, unsigned long ovfl_regs, struct 
pt_regs *regs)
+{
+       pfm_buffer_fmt_t *fmt = ctx->ctx_buf_fmt;
+       pfm_ovfl_ctrl_t rst_ctrl;
+       int state;
+       int ret = 0;
+
+       state = ctx->ctx_state;
+       /*
+        * Unlock sampling buffer and reset index atomically
+        * XXX: not really needed when blocking
+        */
+       if (CTX_HAS_SMPL(ctx)) {
+
+               rst_ctrl.bits.mask_monitoring = 0;
+               rst_ctrl.bits.reset_ovfl_pmds = 0;
+
+               if (state == PFM_CTX_LOADED)
+                       ret = pfm_buf_fmt_restart_active(fmt, current, 
&rst_ctrl, ctx->ctx_smpl_hdr, regs);
+               else
+                       ret = pfm_buf_fmt_restart(fmt, current, &rst_ctrl, 
ctx->ctx_smpl_hdr, regs);
+       } else {
+               rst_ctrl.bits.mask_monitoring = 0;
+               rst_ctrl.bits.reset_ovfl_pmds = 1;
+       }
+
+       if (ret == 0) {
+               if (rst_ctrl.bits.reset_ovfl_pmds) {
+                       pfm_reset_regs(ctx, &ovfl_regs, PFM_PMD_LONG_RESET);
+               }
+               if (rst_ctrl.bits.mask_monitoring == 0) {
+                       DPRINT(("resuming monitoring\n"));
+                       if (ctx->ctx_state == PFM_CTX_MASKED) 
pfm_restore_monitoring(current);
+               } else {
+                       DPRINT(("stopping monitoring\n"));
+                       //pfm_stop_monitoring(current, regs);
+               }
+               ctx->ctx_state = PFM_CTX_LOADED;
+       }
+}
+
+/*
+ * context MUST BE LOCKED when calling
+ * can only be called for current
+ */
+static void
+pfm_context_force_terminate(pfm_context_t *ctx, struct pt_regs *regs)
+{
+       int ret;
+
+       DPRINT(("entering for [%d]\n", current->pid));
+
+       ret = pfm_context_unload(ctx, NULL, 0, regs);
+       if (ret) {
+               printk(KERN_ERR "pfm_context_force_terminate: [%d] unloaded 
failed with %d\n", current->pid, ret);
+       }
+
+       /*
+        * and wakeup controlling task, indicating we are now disconnected
+        */
+       wake_up_interruptible(&ctx->ctx_zombieq);
+
+       /*
+        * given that context is still locked, the controlling
+        * task will only get access when we return from
+        * pfm_handle_work().
+        */
+}
+
+static int pfm_ovfl_notify_user(pfm_context_t *ctx, unsigned long ovfl_pmds);
+ /*
+  * pfm_handle_work() can be called with interrupts enabled
+  * (TIF_NEED_RESCHED) or disabled. The down_interruptible
+  * call may sleep, therefore we must re-enable interrupts
+  * to avoid deadlocks. It is safe to do so because this function
+  * is called ONLY when returning to user level (PUStk=1), in which case
+  * there is no risk of kernel stack overflow due to deep
+  * interrupt nesting.
+  */
+void
+pfm_handle_work(void)
+{
+       pfm_context_t *ctx;
+       struct pt_regs *regs;
+       unsigned long flags, dummy_flags;
+       unsigned long ovfl_regs;
+       unsigned int reason;
+       int ret;
+
+       ctx = PFM_GET_CTX(current);
+       if (ctx == NULL) {
+               printk(KERN_ERR "perfmon: [%d] has no PFM context\n", 
current->pid);
+               return;
+       }
+
+       PROTECT_CTX(ctx, flags);
+
+       PFM_SET_WORK_PENDING(current, 0);
+
+       pfm_clear_task_notify();
+
+       regs = task_pt_regs(current);
+
+       /*
+        * extract reason for being here and clear
+        */
+       reason = ctx->ctx_fl_trap_reason;
+       ctx->ctx_fl_trap_reason = PFM_TRAP_REASON_NONE;
+       ovfl_regs = ctx->ctx_ovfl_regs[0];
+
+       DPRINT(("reason=%d state=%d\n", reason, ctx->ctx_state));
+
+       /*
+        * must be done before we check for simple-reset mode
+        */
+       if (ctx->ctx_fl_going_zombie || ctx->ctx_state == PFM_CTX_ZOMBIE) goto 
do_zombie;
+
+
+       //if (CTX_OVFL_NOBLOCK(ctx)) goto skip_blocking;
+       if (reason == PFM_TRAP_REASON_RESET) goto skip_blocking;
+
+       /*
+        * restore interrupt mask to what it was on entry.
+        * Could be enabled/diasbled.
+        */
+       UNPROTECT_CTX(ctx, flags);
+
+       /*
+        * force interrupt enable because of down_interruptible()
+        */
+       local_irq_enable();
+
+       DPRINT(("before block sleeping\n"));
+
+       /*
+        * may go through without blocking on SMP systems
+        * if restart has been received already by the time we call down()
+        */
+       ret = wait_for_completion_interruptible(&ctx->ctx_restart_done);
+
+       DPRINT(("after block sleeping ret=%d\n", ret));
+
+       /*
+        * lock context and mask interrupts again
+        * We save flags into a dummy because we may have
+        * altered interrupts mask compared to entry in this
+        * function.
+        */
+       PROTECT_CTX(ctx, dummy_flags);
+
+       /*
+        * we need to read the ovfl_regs only after wake-up
+        * because we may have had pfm_write_pmds() in between
+        * and that can changed PMD values and therefore 
+        * ovfl_regs is reset for these new PMD values.
+        */
+       ovfl_regs = ctx->ctx_ovfl_regs[0];
+
+       if (ctx->ctx_fl_going_zombie) {
+do_zombie:
+               DPRINT(("context is zombie, bailing out\n"));
+               pfm_context_force_terminate(ctx, regs);
+               goto nothing_to_do;
+       }
+       /*
+        * in case of interruption of down() we don't restart anything
+        */
+       if (ret < 0) goto nothing_to_do;
+
+skip_blocking:
+       pfm_resume_after_ovfl(ctx, ovfl_regs, regs);
+       ctx->ctx_ovfl_regs[0] = 0UL;
+
+nothing_to_do:
+       /*
+        * restore flags as they were upon entry
+        */
+       UNPROTECT_CTX(ctx, flags);
+}
+
+static int
+pfm_notify_user(pfm_context_t *ctx, pfm_msg_t *msg)
+{
+       if (ctx->ctx_state == PFM_CTX_ZOMBIE) {
+               DPRINT(("ignoring overflow notification, owner is zombie\n"));
+               return 0;
+       }
+
+       DPRINT(("waking up somebody\n"));
+
+       if (msg) wake_up_interruptible(&ctx->ctx_msgq_wait);
+
+       /*
+        * safe, we are not in intr handler, nor in ctxsw when
+        * we come here
+        */
+       kill_fasync (&ctx->ctx_async_queue, SIGIO, POLL_IN);
+
+       return 0;
+}
+
+static int
+pfm_ovfl_notify_user(pfm_context_t *ctx, unsigned long ovfl_pmds)
+{
+       pfm_msg_t *msg = NULL;
+
+       if (ctx->ctx_fl_no_msg == 0) {
+               msg = pfm_get_new_msg(ctx);
+               if (msg == NULL) {
+                       printk(KERN_ERR "perfmon: pfm_ovfl_notify_user no more 
notification msgs\n");
+                       return -1;
+               }
+
+               msg->pfm_ovfl_msg.msg_type         = PFM_MSG_OVFL;
+               msg->pfm_ovfl_msg.msg_ctx_fd       = ctx->ctx_fd;
+               msg->pfm_ovfl_msg.msg_active_set   = 0;
+               msg->pfm_ovfl_msg.msg_ovfl_pmds[0] = ovfl_pmds;
+               msg->pfm_ovfl_msg.msg_ovfl_pmds[1] = 0UL;
+               msg->pfm_ovfl_msg.msg_ovfl_pmds[2] = 0UL;
+               msg->pfm_ovfl_msg.msg_ovfl_pmds[3] = 0UL;
+               msg->pfm_ovfl_msg.msg_tstamp       = 0UL;
+       }
+
+       DPRINT(("ovfl msg: msg=%p no_msg=%d fd=%d ovfl_pmds=0x%lx\n",
+               msg,
+               ctx->ctx_fl_no_msg,
+               ctx->ctx_fd,
+               ovfl_pmds));
+
+       return pfm_notify_user(ctx, msg);
+}
+
+static int
+pfm_end_notify_user(pfm_context_t *ctx)
+{
+       pfm_msg_t *msg;
+
+       msg = pfm_get_new_msg(ctx);
+       if (msg == NULL) {
+               printk(KERN_ERR "perfmon: pfm_end_notify_user no more 
notification msgs\n");
+               return -1;
+       }
+       /* no leak */
+       memset(msg, 0, sizeof(*msg));
+
+       msg->pfm_end_msg.msg_type    = PFM_MSG_END;
+       msg->pfm_end_msg.msg_ctx_fd  = ctx->ctx_fd;
+       msg->pfm_ovfl_msg.msg_tstamp = 0UL;
+
+       DPRINT(("end msg: msg=%p no_msg=%d ctx_fd=%d\n",
+               msg,
+               ctx->ctx_fl_no_msg,
+               ctx->ctx_fd));
+
+       return pfm_notify_user(ctx, msg);
+}
+
+/*
+ * main overflow processing routine.
+ * it can be called from the interrupt path or explicitely during the context 
switch code
+ */
+static void
+pfm_overflow_handler(struct task_struct *task, pfm_context_t *ctx, u64 pmc0, 
struct pt_regs *regs)
+{
+       pfm_ovfl_arg_t *ovfl_arg;
+       unsigned long mask;
+       unsigned long old_val, ovfl_val, new_val;
+       unsigned long ovfl_notify = 0UL, ovfl_pmds = 0UL, smpl_pmds = 0UL, 
reset_pmds;
+       unsigned long tstamp;
+       pfm_ovfl_ctrl_t ovfl_ctrl;
+       unsigned int i, has_smpl;
+       int must_notify = 0;
+
+       if (unlikely(ctx->ctx_state == PFM_CTX_ZOMBIE)) goto stop_monitoring;
+
+       /*
+        * sanity test. Should never happen
+        */
+       if (unlikely((pmc0 & 0x1) == 0)) goto sanity_check;
+
+       tstamp   = ia64_get_itc();
+       mask     = pmc0 >> PMU_FIRST_COUNTER;
+       ovfl_val = pmu_conf->ovfl_val;
+       has_smpl = CTX_HAS_SMPL(ctx);
+
+       DPRINT_ovfl(("pmc0=0x%lx pid=%d iip=0x%lx, %s "
+                    "used_pmds=0x%lx\n",
+                       pmc0,
+                       task ? task->pid: -1,
+                       (regs ? regs->cr_iip : 0),
+                       CTX_OVFL_NOBLOCK(ctx) ? "nonblocking" : "blocking",
+                       ctx->ctx_used_pmds[0]));
+
+
+       /*
+        * first we update the virtual counters
+        * assume there was a prior ia64_srlz_d() issued
+        */
+       for (i = PMU_FIRST_COUNTER; mask ; i++, mask >>= 1) {
+
+               /* skip pmd which did not overflow */
+               if ((mask & 0x1) == 0) continue;
+
+               /*
+                * Note that the pmd is not necessarily 0 at this point as 
qualified events
+                * may have happened before the PMU was frozen. The residual 
count is not
+                * taken into consideration here but will be with any read of 
the pmd via
+                * pfm_read_pmds().
+                */
+               old_val              = new_val = ctx->ctx_pmds[i].val;
+               new_val             += 1 + ovfl_val;
+               ctx->ctx_pmds[i].val = new_val;
+
+               /*
+                * check for overflow condition
+                */
+               if (likely(old_val > new_val)) {
+                       ovfl_pmds |= 1UL << i;
+                       if (PMC_OVFL_NOTIFY(ctx, i)) ovfl_notify |= 1UL << i;
+               }
+
+               DPRINT_ovfl(("ctx_pmd[%d].val=0x%lx old_val=0x%lx pmd=0x%lx 
ovfl_pmds=0x%lx ovfl_notify=0x%lx\n",
+                       i,
+                       new_val,
+                       old_val,
+                       ia64_get_pmd(i) & ovfl_val,
+                       ovfl_pmds,
+                       ovfl_notify));
+       }
+
+       /*
+        * there was no 64-bit overflow, nothing else to do
+        */
+       if (ovfl_pmds == 0UL) return;
+
+       /* 
+        * reset all control bits
+        */
+       ovfl_ctrl.val = 0;
+       reset_pmds    = 0UL;
+
+       /*
+        * if a sampling format module exists, then we "cache" the overflow by 
+        * calling the module's handler() routine.
+        */
+       if (has_smpl) {
+               unsigned long start_cycles, end_cycles;
+               unsigned long pmd_mask;
+               int j, k, ret = 0;
+               int this_cpu = smp_processor_id();
+
+               pmd_mask = ovfl_pmds >> PMU_FIRST_COUNTER;
+               ovfl_arg = &ctx->ctx_ovfl_arg;
+
+               prefetch(ctx->ctx_smpl_hdr);
+
+               for(i=PMU_FIRST_COUNTER; pmd_mask && ret == 0; i++, pmd_mask 
>>=1) {
+
+                       mask = 1UL << i;
+
+                       if ((pmd_mask & 0x1) == 0) continue;
+
+                       ovfl_arg->ovfl_pmd      = (unsigned char )i;
+                       ovfl_arg->ovfl_notify   = ovfl_notify & mask ? 1 : 0;
+                       ovfl_arg->active_set    = 0;
+                       ovfl_arg->ovfl_ctrl.val = 0; /* module must fill in all 
fields */
+                       ovfl_arg->smpl_pmds[0]  = smpl_pmds = 
ctx->ctx_pmds[i].smpl_pmds[0];
+
+                       ovfl_arg->pmd_value      = ctx->ctx_pmds[i].val;
+                       ovfl_arg->pmd_last_reset = ctx->ctx_pmds[i].lval;
+                       ovfl_arg->pmd_eventid    = ctx->ctx_pmds[i].eventid;
+
+                       /*
+                        * copy values of pmds of interest. Sampling format may 
copy them
+                        * into sampling buffer.
+                        */
+                       if (smpl_pmds) {
+                               for(j=0, k=0; smpl_pmds; j++, smpl_pmds >>=1) {
+                                       if ((smpl_pmds & 0x1) == 0) continue;
+                                       ovfl_arg->smpl_pmds_values[k++] = 
PMD_IS_COUNTING(j) ?  pfm_read_soft_counter(ctx, j) : ia64_get_pmd(j);
+                                       
DPRINT_ovfl(("smpl_pmd[%d]=pmd%u=0x%lx\n", k-1, j, 
ovfl_arg->smpl_pmds_values[k-1]));
+                               }
+                       }
+
+                       pfm_stats[this_cpu].pfm_smpl_handler_calls++;
+
+                       start_cycles = ia64_get_itc();
+
+                       /*
+                        * call custom buffer format record (handler) routine
+                        */
+                       ret = (*ctx->ctx_buf_fmt->fmt_handler)(task, 
ctx->ctx_smpl_hdr, ovfl_arg, regs, tstamp);
+
+                       end_cycles = ia64_get_itc();
+
+                       /*
+                        * For those controls, we take the union because they 
have
+                        * an all or nothing behavior.
+                        */
+                       ovfl_ctrl.bits.notify_user     |= 
ovfl_arg->ovfl_ctrl.bits.notify_user;
+                       ovfl_ctrl.bits.block_task      |= 
ovfl_arg->ovfl_ctrl.bits.block_task;
+                       ovfl_ctrl.bits.mask_monitoring |= 
ovfl_arg->ovfl_ctrl.bits.mask_monitoring;
+                       /*
+                        * build the bitmask of pmds to reset now
+                        */
+                       if (ovfl_arg->ovfl_ctrl.bits.reset_ovfl_pmds) 
reset_pmds |= mask;
+
+                       pfm_stats[this_cpu].pfm_smpl_handler_cycles += 
end_cycles - start_cycles;
+               }
+               /*
+                * when the module cannot handle the rest of the overflows, we 
abort right here
+                */
+               if (ret && pmd_mask) {
+                       DPRINT(("handler aborts leftover ovfl_pmds=0x%lx\n",
+                               pmd_mask<<PMU_FIRST_COUNTER));
+               }
+               /*
+                * remove the pmds we reset now from the set of pmds to reset 
in pfm_restart()
+                */
+               ovfl_pmds &= ~reset_pmds;
+       } else {
+               /*
+                * when no sampling module is used, then the default
+                * is to notify on overflow if requested by user
+                */
+               ovfl_ctrl.bits.notify_user     = ovfl_notify ? 1 : 0;
+               ovfl_ctrl.bits.block_task      = ovfl_notify ? 1 : 0;
+               ovfl_ctrl.bits.mask_monitoring = ovfl_notify ? 1 : 0; /* XXX: 
change for saturation */
+               ovfl_ctrl.bits.reset_ovfl_pmds = ovfl_notify ? 0 : 1;
+               /*
+                * if needed, we reset all overflowed pmds
+                */
+               if (ovfl_notify == 0) reset_pmds = ovfl_pmds;
+       }
+
+       DPRINT_ovfl(("ovfl_pmds=0x%lx reset_pmds=0x%lx\n", ovfl_pmds, 
reset_pmds));
+
+       /*
+        * reset the requested PMD registers using the short reset values
+        */
+       if (reset_pmds) {
+               unsigned long bm = reset_pmds;
+               pfm_reset_regs(ctx, &bm, PFM_PMD_SHORT_RESET);
+       }
+
+       if (ovfl_notify && ovfl_ctrl.bits.notify_user) {
+               /*
+                * keep track of what to reset when unblocking
+                */
+               ctx->ctx_ovfl_regs[0] = ovfl_pmds;
+
+               /*
+                * check for blocking context 
+                */
+               if (CTX_OVFL_NOBLOCK(ctx) == 0 && ovfl_ctrl.bits.block_task) {
+
+                       ctx->ctx_fl_trap_reason = PFM_TRAP_REASON_BLOCK;
+
+                       /*
+                        * set the perfmon specific checking pending work for 
the task
+                        */
+                       PFM_SET_WORK_PENDING(task, 1);
+
+                       /*
+                        * when coming from ctxsw, current still points to the
+                        * previous task, therefore we must work with task and 
not current.
+                        */
+                       pfm_set_task_notify(task);
+               }
+               /*
+                * defer until state is changed (shorten spin window). the 
context is locked
+                * anyway, so the signal receiver would come spin for nothing.
+                */
+               must_notify = 1;
+       }
+
+       DPRINT_ovfl(("owner [%d] pending=%ld reason=%u ovfl_pmds=0x%lx 
ovfl_notify=0x%lx masked=%d\n",
+                       GET_PMU_OWNER() ? GET_PMU_OWNER()->pid : -1,
+                       PFM_GET_WORK_PENDING(task),
+                       ctx->ctx_fl_trap_reason,
+                       ovfl_pmds,
+                       ovfl_notify,
+                       ovfl_ctrl.bits.mask_monitoring ? 1 : 0));
+       /*
+        * in case monitoring must be stopped, we toggle the psr bits
+        */
+       if (ovfl_ctrl.bits.mask_monitoring) {
+               pfm_mask_monitoring(task);
+               ctx->ctx_state = PFM_CTX_MASKED;
+               ctx->ctx_fl_can_restart = 1;
+       }
+
+       /*
+        * send notification now
+        */
+       if (must_notify) pfm_ovfl_notify_user(ctx, ovfl_notify);
+
+       return;
+
+sanity_check:
+       printk(KERN_ERR "perfmon: CPU%d overflow handler [%d] pmc0=0x%lx\n",
+                       smp_processor_id(),
+                       task ? task->pid : -1,
+                       pmc0);
+       return;
+
+stop_monitoring:
+       /*
+        * in SMP, zombie context is never restored but reclaimed in 
pfm_load_regs().
+        * Moreover, zombies are also reclaimed in pfm_save_regs(). Therefore 
we can
+        * come here as zombie only if the task is the current task. In which 
case, we
+        * can access the PMU  hardware directly.
+        *
+        * Note that zombies do have PM_VALID set. So here we do the minimal.
+        *
+        * In case the context was zombified it could not be reclaimed at the 
time
+        * the monitoring program exited. At this point, the PMU reservation 
has been
+        * returned, the sampiing buffer has been freed. We must convert this 
call
+        * into a spurious interrupt. However, we must also avoid infinite 
overflows
+        * by stopping monitoring for this task. We can only come here for a 
per-task
+        * context. All we need to do is to stop monitoring using the psr bits 
which
+        * are always task private. By re-enabling secure montioring, we ensure 
that
+        * the monitored task will not be able to re-activate monitoring.
+        * The task will eventually be context switched out, at which point the 
context
+        * will be reclaimed (that includes releasing ownership of the PMU).
+        *
+        * So there might be a window of time where the number of per-task 
session is zero
+        * yet one PMU might have a owner and get at most one overflow 
interrupt for a zombie
+        * context. This is safe because if a per-task session comes in, it 
will push this one
+        * out and by the virtue on pfm_save_regs(), this one will disappear. 
If a system wide
+        * session is force on that CPU, given that we use task pinning, 
pfm_save_regs() will
+        * also push our zombie context out.
+        *
+        * Overall pretty hairy stuff....
+        */
+       DPRINT(("ctx is zombie for [%d], converted to spurious\n", task ? 
task->pid: -1));
+       pfm_clear_psr_up();
+       ia64_psr(regs)->up = 0;
+       ia64_psr(regs)->sp = 1;
+       return;
+}
+
+static int
+pfm_do_interrupt_handler(int irq, void *arg, struct pt_regs *regs)
+{
+       struct task_struct *task;
+       pfm_context_t *ctx;
+       unsigned long flags;
+       u64 pmc0;
+       int this_cpu = smp_processor_id();
+       int retval = 0;
+
+       pfm_stats[this_cpu].pfm_ovfl_intr_count++;
+
+       /*
+        * srlz.d done before arriving here
+        */
+       pmc0 = ia64_get_pmc(0);
+
+       task = GET_PMU_OWNER();
+       ctx  = GET_PMU_CTX();
+
+       /*
+        * if we have some pending bits set
+        * assumes : if any PMC0.bit[63-1] is set, then PMC0.fr = 1
+        */
+       if (PMC0_HAS_OVFL(pmc0) && task) {
+               /*
+                * we assume that pmc0.fr is always set here
+                */
+
+               /* sanity check */
+               if (!ctx) goto report_spurious1;
+
+               if (ctx->ctx_fl_system == 0 && (task->thread.flags & 
IA64_THREAD_PM_VALID) == 0) 
+                       goto report_spurious2;
+
+               PROTECT_CTX_NOPRINT(ctx, flags);
+
+               pfm_overflow_handler(task, ctx, pmc0, regs);
+
+               UNPROTECT_CTX_NOPRINT(ctx, flags);
+
+       } else {
+               pfm_stats[this_cpu].pfm_spurious_ovfl_intr_count++;
+               retval = -1;
+       }
+       /*
+        * keep it unfrozen at all times
+        */
+       pfm_unfreeze_pmu();
+
+       return retval;
+
+report_spurious1:
+       printk(KERN_INFO "perfmon: spurious overflow interrupt on CPU%d: 
process %d has no PFM context\n",
+               this_cpu, task->pid);
+       pfm_unfreeze_pmu();
+       return -1;
+report_spurious2:
+       printk(KERN_INFO "perfmon: spurious overflow interrupt on CPU%d: 
process %d, invalid flag\n", 
+               this_cpu, 
+               task->pid);
+       pfm_unfreeze_pmu();
+       return -1;
+}
+
+static irqreturn_t
+pfm_interrupt_handler(int irq, void *arg, struct pt_regs *regs)
+{
+       unsigned long start_cycles, total_cycles;
+       unsigned long min, max;
+       int this_cpu;
+       int ret;
+
+       this_cpu = get_cpu();
+       if (likely(!pfm_alt_intr_handler)) {
+               min = pfm_stats[this_cpu].pfm_ovfl_intr_cycles_min;
+               max = pfm_stats[this_cpu].pfm_ovfl_intr_cycles_max;
+
+               start_cycles = ia64_get_itc();
+
+               ret = pfm_do_interrupt_handler(irq, arg, regs);
+
+               total_cycles = ia64_get_itc();
+
+               /*
+                * don't measure spurious interrupts
+                */
+               if (likely(ret == 0)) {
+                       total_cycles -= start_cycles;
+
+                       if (total_cycles < min) 
pfm_stats[this_cpu].pfm_ovfl_intr_cycles_min = total_cycles;
+                       if (total_cycles > max) 
pfm_stats[this_cpu].pfm_ovfl_intr_cycles_max = total_cycles;
+
+                       pfm_stats[this_cpu].pfm_ovfl_intr_cycles += 
total_cycles;
+               }
+       }
+       else {
+               (*pfm_alt_intr_handler->handler)(irq, arg, regs);
+       }
+
+       put_cpu_no_resched();
+       return IRQ_HANDLED;
+}
+
+/*
+ * /proc/perfmon interface, for debug only
+ */
+
+#define PFM_PROC_SHOW_HEADER   ((void *)NR_CPUS+1)
+
+static void *
+pfm_proc_start(struct seq_file *m, loff_t *pos)
+{
+       if (*pos == 0) {
+               return PFM_PROC_SHOW_HEADER;
+       }
+
+       while (*pos <= NR_CPUS) {
+               if (cpu_online(*pos - 1)) {
+                       return (void *)*pos;
+               }
+               ++*pos;
+       }
+       return NULL;
+}
+
+static void *
+pfm_proc_next(struct seq_file *m, void *v, loff_t *pos)
+{
+       ++*pos;
+       return pfm_proc_start(m, pos);
+}
+
+static void
+pfm_proc_stop(struct seq_file *m, void *v)
+{
+}
+
+static void
+pfm_proc_show_header(struct seq_file *m)
+{
+       struct list_head * pos;
+       pfm_buffer_fmt_t * entry;
+       unsigned long flags;
+
+       seq_printf(m,
+               "perfmon version           : %u.%u\n"
+               "model                     : %s\n"
+               "fastctxsw                 : %s\n"
+               "expert mode               : %s\n"
+               "ovfl_mask                 : 0x%lx\n"
+               "PMU flags                 : 0x%x\n",
+               PFM_VERSION_MAJ, PFM_VERSION_MIN,
+               pmu_conf->pmu_name,
+               pfm_sysctl.fastctxsw > 0 ? "Yes": "No",
+               pfm_sysctl.expert_mode > 0 ? "Yes": "No",
+               pmu_conf->ovfl_val,
+               pmu_conf->flags);
+
+       LOCK_PFS(flags);
+
+       seq_printf(m,
+               "proc_sessions             : %u\n"
+               "sys_sessions              : %u\n"
+               "sys_use_dbregs            : %u\n"
+               "ptrace_use_dbregs         : %u\n",
+               pfm_sessions.pfs_task_sessions,
+               pfm_sessions.pfs_sys_sessions,
+               pfm_sessions.pfs_sys_use_dbregs,
+               pfm_sessions.pfs_ptrace_use_dbregs);
+
+       UNLOCK_PFS(flags);
+
+       spin_lock(&pfm_buffer_fmt_lock);
+
+       list_for_each(pos, &pfm_buffer_fmt_list) {
+               entry = list_entry(pos, pfm_buffer_fmt_t, fmt_list);
+               seq_printf(m, "format                    : 
%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x 
%s\n",
+                       entry->fmt_uuid[0],
+                       entry->fmt_uuid[1],
+                       entry->fmt_uuid[2],
+                       entry->fmt_uuid[3],
+                       entry->fmt_uuid[4],
+                       entry->fmt_uuid[5],
+                       entry->fmt_uuid[6],
+                       entry->fmt_uuid[7],
+                       entry->fmt_uuid[8],
+                       entry->fmt_uuid[9],
+                       entry->fmt_uuid[10],
+                       entry->fmt_uuid[11],
+                       entry->fmt_uuid[12],
+                       entry->fmt_uuid[13],
+                       entry->fmt_uuid[14],
+                       entry->fmt_uuid[15],
+                       entry->fmt_name);
+       }
+       spin_unlock(&pfm_buffer_fmt_lock);
+
+}
+
+static int
+pfm_proc_show(struct seq_file *m, void *v)
+{
+       unsigned long psr;
+       unsigned int i;
+       int cpu;
+
+       if (v == PFM_PROC_SHOW_HEADER) {
+               pfm_proc_show_header(m);
+               return 0;
+       }
+
+       /* show info for CPU (v - 1) */
+
+       cpu = (long)v - 1;
+       seq_printf(m,
+               "CPU%-2d overflow intrs      : %lu\n"
+               "CPU%-2d overflow cycles     : %lu\n"
+               "CPU%-2d overflow min        : %lu\n"
+               "CPU%-2d overflow max        : %lu\n"
+               "CPU%-2d smpl handler calls  : %lu\n"
+               "CPU%-2d smpl handler cycles : %lu\n"
+               "CPU%-2d spurious intrs      : %lu\n"
+               "CPU%-2d replay   intrs      : %lu\n"
+               "CPU%-2d syst_wide           : %d\n"
+               "CPU%-2d dcr_pp              : %d\n"
+               "CPU%-2d exclude idle        : %d\n"
+               "CPU%-2d owner               : %d\n"
+               "CPU%-2d context             : %p\n"
+               "CPU%-2d activations         : %lu\n",
+               cpu, pfm_stats[cpu].pfm_ovfl_intr_count,
+               cpu, pfm_stats[cpu].pfm_ovfl_intr_cycles,
+               cpu, pfm_stats[cpu].pfm_ovfl_intr_cycles_min,
+               cpu, pfm_stats[cpu].pfm_ovfl_intr_cycles_max,
+               cpu, pfm_stats[cpu].pfm_smpl_handler_calls,
+               cpu, pfm_stats[cpu].pfm_smpl_handler_cycles,
+               cpu, pfm_stats[cpu].pfm_spurious_ovfl_intr_count,
+               cpu, pfm_stats[cpu].pfm_replay_ovfl_intr_count,
+               cpu, pfm_get_cpu_data(pfm_syst_info, cpu) & 
PFM_CPUINFO_SYST_WIDE ? 1 : 0,
+               cpu, pfm_get_cpu_data(pfm_syst_info, cpu) & PFM_CPUINFO_DCR_PP 
? 1 : 0,
+               cpu, pfm_get_cpu_data(pfm_syst_info, cpu) & 
PFM_CPUINFO_EXCL_IDLE ? 1 : 0,
+               cpu, pfm_get_cpu_data(pmu_owner, cpu) ? 
pfm_get_cpu_data(pmu_owner, cpu)->pid: -1,
+               cpu, pfm_get_cpu_data(pmu_ctx, cpu),
+               cpu, pfm_get_cpu_data(pmu_activation_number, cpu));
+
+       if (num_online_cpus() == 1 && pfm_sysctl.debug > 0) {
+
+               psr = pfm_get_psr();
+
+               ia64_srlz_d();
+
+               seq_printf(m, 
+                       "CPU%-2d psr                 : 0x%lx\n"
+                       "CPU%-2d pmc0                : 0x%lx\n", 
+                       cpu, psr,
+                       cpu, ia64_get_pmc(0));
+
+               for (i=0; PMC_IS_LAST(i) == 0;  i++) {
+                       if (PMC_IS_COUNTING(i) == 0) continue;
+                       seq_printf(m, 
+                               "CPU%-2d pmc%u                : 0x%lx\n"
+                               "CPU%-2d pmd%u                : 0x%lx\n", 
+                               cpu, i, ia64_get_pmc(i),
+                               cpu, i, ia64_get_pmd(i));
+               }
+       }
+       return 0;
+}
+
+struct seq_operations pfm_seq_ops = {
+       .start =        pfm_proc_start,
+       .next =         pfm_proc_next,
+       .stop =         pfm_proc_stop,
+       .show =         pfm_proc_show
+};
+
+static int
+pfm_proc_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &pfm_seq_ops);
+}
+
+
+/*
+ * we come here as soon as local_cpu_data->pfm_syst_wide is set. this happens
+ * during pfm_enable() hence before pfm_start(). We cannot assume monitoring
+ * is active or inactive based on mode. We must rely on the value in
+ * local_cpu_data->pfm_syst_info
+ */
+void
+pfm_syst_wide_update_task(struct task_struct *task, unsigned long info, int 
is_ctxswin)
+{
+       struct pt_regs *regs;
+       unsigned long dcr;
+       unsigned long dcr_pp;
+
+       dcr_pp = info & PFM_CPUINFO_DCR_PP ? 1 : 0;
+
+       /*
+        * pid 0 is guaranteed to be the idle task. There is one such task with 
pid 0
+        * on every CPU, so we can rely on the pid to identify the idle task.
+        */
+       if ((info & PFM_CPUINFO_EXCL_IDLE) == 0 || task->pid) {
+               regs = task_pt_regs(task);
+               ia64_psr(regs)->pp = is_ctxswin ? dcr_pp : 0;
+               return;
+       }
+       /*
+        * if monitoring has started
+        */
+       if (dcr_pp) {
+               dcr = ia64_getreg(_IA64_REG_CR_DCR);
+               /*
+                * context switching in?
+                */
+               if (is_ctxswin) {
+                       /* mask monitoring for the idle task */
+                       ia64_setreg(_IA64_REG_CR_DCR, dcr & ~IA64_DCR_PP);
+                       pfm_clear_psr_pp();
+                       ia64_srlz_i();
+                       return;
+               }
+               /*
+                * context switching out
+                * restore monitoring for next task
+                *
+                * Due to inlining this odd if-then-else construction generates
+                * better code.
+                */
+               ia64_setreg(_IA64_REG_CR_DCR, dcr |IA64_DCR_PP);
+               pfm_set_psr_pp();
+               ia64_srlz_i();
+       }
+}
+
+#ifdef CONFIG_SMP
+
+static void
+pfm_force_cleanup(pfm_context_t *ctx, struct pt_regs *regs)
+{
+       struct task_struct *task = ctx->ctx_task;
+
+       ia64_psr(regs)->up = 0;
+       ia64_psr(regs)->sp = 1;
+
+       if (GET_PMU_OWNER() == task) {
+               DPRINT(("cleared ownership for [%d]\n", ctx->ctx_task->pid));
+               SET_PMU_OWNER(NULL, NULL);
+       }
+
+       /*
+        * disconnect the task from the context and vice-versa
+        */
+       PFM_SET_WORK_PENDING(task, 0);
+
+       task->thread.pfm_context  = NULL;
+       task->thread.flags       &= ~IA64_THREAD_PM_VALID;
+
+       DPRINT(("force cleanup for [%d]\n",  task->pid));
+}
+
+
+/*
+ * in 2.6, interrupts are masked when we come here and the runqueue lock is 
held
+ */
+void
+pfm_save_regs(struct task_struct *task)
+{
+       pfm_context_t *ctx;
+       struct thread_struct *t;
+       unsigned long flags;
+       u64 psr;
+
+
+       ctx = PFM_GET_CTX(task);
+       if (ctx == NULL) return;
+       t = &task->thread;
+
+       /*
+        * we always come here with interrupts ALREADY disabled by
+        * the scheduler. So we simply need to protect against concurrent
+        * access, not CPU concurrency.
+        */
+       flags = pfm_protect_ctx_ctxsw(ctx);
+
+       if (ctx->ctx_state == PFM_CTX_ZOMBIE) {
+               struct pt_regs *regs = task_pt_regs(task);
+
+               pfm_clear_psr_up();
+
+               pfm_force_cleanup(ctx, regs);
+
+               BUG_ON(ctx->ctx_smpl_hdr);
+
+               pfm_unprotect_ctx_ctxsw(ctx, flags);
+
+               pfm_context_free(ctx);
+               return;
+       }
+
+       /*
+        * save current PSR: needed because we modify it
+        */
+       ia64_srlz_d();
+       psr = pfm_get_psr();
+
+       BUG_ON(psr & (IA64_PSR_I));
+
+       /*
+        * stop monitoring:
+        * This is the last instruction which may generate an overflow
+        *
+        * We do not need to set psr.sp because, it is irrelevant in kernel.
+        * It will be restored from ipsr when going back to user level
+        */
+       pfm_clear_psr_up();
+
+       /*
+        * keep a copy of psr.up (for reload)
+        */
+       ctx->ctx_saved_psr_up = psr & IA64_PSR_UP;
+
+       /*
+        * release ownership of this PMU.
+        * PM interrupts are masked, so nothing
+        * can happen.
+        */
+       SET_PMU_OWNER(NULL, NULL);
+
+       /*
+        * we systematically save the PMD as we have no
+        * guarantee we will be schedule at that same
+        * CPU again.
+        */
+       pfm_save_pmds(t->pmds, ctx->ctx_used_pmds[0]);
+
+       /*
+        * save pmc0 ia64_srlz_d() done in pfm_save_pmds()
+        * we will need it on the restore path to check
+        * for pending overflow.
+        */
+       t->pmcs[0] = ia64_get_pmc(0);
+
+       /*
+        * unfreeze PMU if had pending overflows
+        */
+       if (t->pmcs[0] & ~0x1UL) pfm_unfreeze_pmu();
+
+       /*
+        * finally, allow context access.
+        * interrupts will still be masked after this call.
+        */
+       pfm_unprotect_ctx_ctxsw(ctx, flags);
+}
+
+#else /* !CONFIG_SMP */
+void
+pfm_save_regs(struct task_struct *task)
+{
+       pfm_context_t *ctx;
+       u64 psr;
+
+       ctx = PFM_GET_CTX(task);
+       if (ctx == NULL) return;
+
+       /*
+        * save current PSR: needed because we modify it
+        */
+       psr = pfm_get_psr();
+
+       BUG_ON(psr & (IA64_PSR_I));
+
+       /*
+        * stop monitoring:
+        * This is the last instruction which may generate an overflow
+        *
+        * We do not need to set psr.sp because, it is irrelevant in kernel.
+        * It will be restored from ipsr when going back to user level
+        */
+       pfm_clear_psr_up();
+
+       /*
+        * keep a copy of psr.up (for reload)
+        */
+       ctx->ctx_saved_psr_up = psr & IA64_PSR_UP;
+}
+
+static void
+pfm_lazy_save_regs (struct task_struct *task)
+{
+       pfm_context_t *ctx;
+       struct thread_struct *t;
+       unsigned long flags;
+
+       { u64 psr  = pfm_get_psr();
+         BUG_ON(psr & IA64_PSR_UP);
+       }
+
+       ctx = PFM_GET_CTX(task);
+       t   = &task->thread;
+
+       /*
+        * we need to mask PMU overflow here to
+        * make sure that we maintain pmc0 until
+        * we save it. overflow interrupts are
+        * treated as spurious if there is no
+        * owner.
+        *
+        * XXX: I don't think this is necessary
+        */
+       PROTECT_CTX(ctx,flags);
+
+       /*
+        * release ownership of this PMU.
+        * must be done before we save the registers.
+        *
+        * after this call any PMU interrupt is treated
+        * as spurious.
+        */
+       SET_PMU_OWNER(NULL, NULL);
+
+       /*
+        * save all the pmds we use
+        */
+       pfm_save_pmds(t->pmds, ctx->ctx_used_pmds[0]);
+
+       /*
+        * save pmc0 ia64_srlz_d() done in pfm_save_pmds()
+        * it is needed to check for pended overflow
+        * on the restore path
+        */
+       t->pmcs[0] = ia64_get_pmc(0);
+
+       /*
+        * unfreeze PMU if had pending overflows
+        */
+       if (t->pmcs[0] & ~0x1UL) pfm_unfreeze_pmu();
+
+       /*
+        * now get can unmask PMU interrupts, they will
+        * be treated as purely spurious and we will not
+        * lose any information
+        */
+       UNPROTECT_CTX(ctx,flags);
+}
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_SMP
+/*
+ * in 2.6, interrupts are masked when we come here and the runqueue lock is 
held
+ */
+void
+pfm_load_regs (struct task_struct *task)
+{
+       pfm_context_t *ctx;
+       struct thread_struct *t;
+       unsigned long pmc_mask = 0UL, pmd_mask = 0UL;
+       unsigned long flags;
+       u64 psr, psr_up;
+       int need_irq_resend;
+
+       ctx = PFM_GET_CTX(task);
+       if (unlikely(ctx == NULL)) return;
+
+       BUG_ON(GET_PMU_OWNER());
+
+       t     = &task->thread;
+       /*
+        * possible on unload
+        */
+       if (unlikely((t->flags & IA64_THREAD_PM_VALID) == 0)) return;
+
+       /*
+        * we always come here with interrupts ALREADY disabled by
+        * the scheduler. So we simply need to protect against concurrent
+        * access, not CPU concurrency.
+        */
+       flags = pfm_protect_ctx_ctxsw(ctx);
+       psr   = pfm_get_psr();
+
+       need_irq_resend = pmu_conf->flags & PFM_PMU_IRQ_RESEND;
+
+       BUG_ON(psr & (IA64_PSR_UP|IA64_PSR_PP));
+       BUG_ON(psr & IA64_PSR_I);
+
+       if (unlikely(ctx->ctx_state == PFM_CTX_ZOMBIE)) {
+               struct pt_regs *regs = task_pt_regs(task);
+
+               BUG_ON(ctx->ctx_smpl_hdr);
+
+               pfm_force_cleanup(ctx, regs);
+
+               pfm_unprotect_ctx_ctxsw(ctx, flags);
+
+               /*
+                * this one (kmalloc'ed) is fine with interrupts disabled
+                */
+               pfm_context_free(ctx);
+
+               return;
+       }
+
+       /*
+        * we restore ALL the debug registers to avoid picking up
+        * stale state.
+        */
+       if (ctx->ctx_fl_using_dbreg) {
+               pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
+               pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
+       }
+       /*
+        * retrieve saved psr.up
+        */
+       psr_up = ctx->ctx_saved_psr_up;
+
+       /*
+        * if we were the last user of the PMU on that CPU,
+        * then nothing to do except restore psr
+        */
+       if (GET_LAST_CPU(ctx) == smp_processor_id() && ctx->ctx_last_activation 
== GET_ACTIVATION()) {
+
+               /*
+                * retrieve partial reload masks (due to user modifications)
+                */
+               pmc_mask = ctx->ctx_reload_pmcs[0];
+               pmd_mask = ctx->ctx_reload_pmds[0];
+
+       } else {
+               /*
+                * To avoid leaking information to the user level when psr.sp=0,
+                * we must reload ALL implemented pmds (even the ones we don't 
use).
+                * In the kernel we only allow PFM_READ_PMDS on registers which
+                * we initialized or requested (sampling) so there is no risk 
there.
+                */
+               pmd_mask = pfm_sysctl.fastctxsw ?  ctx->ctx_used_pmds[0] : 
ctx->ctx_all_pmds[0];
+
+               /*
+                * ALL accessible PMCs are systematically reloaded, unused 
registers
+                * get their default (from pfm_reset_pmu_state()) values to 
avoid picking
+                * up stale configuration.
+                *
+                * PMC0 is never in the mask. It is always restored separately.
+                */
+               pmc_mask = ctx->ctx_all_pmcs[0];
+       }
+       /*
+        * when context is MASKED, we will restore PMC with plm=0
+        * and PMD with stale information, but that's ok, nothing
+        * will be captured.
+        *
+        * XXX: optimize here
+        */
+       if (pmd_mask) pfm_restore_pmds(t->pmds, pmd_mask);
+       if (pmc_mask) pfm_restore_pmcs(t->pmcs, pmc_mask);
+
+       /*
+        * check for pending overflow at the time the state
+        * was saved.
+        */
+       if (unlikely(PMC0_HAS_OVFL(t->pmcs[0]))) {
+               /*
+                * reload pmc0 with the overflow information
+                * On McKinley PMU, this will trigger a PMU interrupt
+                */
+               ia64_set_pmc(0, t->pmcs[0]);
+               ia64_srlz_d();
+               t->pmcs[0] = 0UL;
+
+               /*
+                * will replay the PMU interrupt
+                */
+               if (need_irq_resend) hw_resend_irq(NULL, IA64_PERFMON_VECTOR);
+
+               pfm_stats[smp_processor_id()].pfm_replay_ovfl_intr_count++;
+       }
+
+       /*
+        * we just did a reload, so we reset the partial reload fields
+        */
+       ctx->ctx_reload_pmcs[0] = 0UL;
+       ctx->ctx_reload_pmds[0] = 0UL;
+
+       SET_LAST_CPU(ctx, smp_processor_id());
+
+       /*
+        * dump activation value for this PMU
+        */
+       INC_ACTIVATION();
+       /*
+        * record current activation for this context
+        */
+       SET_ACTIVATION(ctx);
+
+       /*
+        * establish new ownership. 
+        */
+       SET_PMU_OWNER(task, ctx);
+
+       /*
+        * restore the psr.up bit. measurement
+        * is active again.
+        * no PMU interrupt can happen at this point
+        * because we still have interrupts disabled.
+        */
+       if (likely(psr_up)) pfm_set_psr_up();
+
+       /*
+        * allow concurrent access to context
+        */
+       pfm_unprotect_ctx_ctxsw(ctx, flags);
+}
+#else /*  !CONFIG_SMP */
+/*
+ * reload PMU state for UP kernels
+ * in 2.5 we come here with interrupts disabled
+ */
+void
+pfm_load_regs (struct task_struct *task)
+{
+       struct thread_struct *t;
+       pfm_context_t *ctx;
+       struct task_struct *owner;
+       unsigned long pmd_mask, pmc_mask;
+       u64 psr, psr_up;
+       int need_irq_resend;
+
+       owner = GET_PMU_OWNER();
+       ctx   = PFM_GET_CTX(task);
+       t     = &task->thread;
+       psr   = pfm_get_psr();
+
+       BUG_ON(psr & (IA64_PSR_UP|IA64_PSR_PP));
+       BUG_ON(psr & IA64_PSR_I);
+
+       /*
+        * we restore ALL the debug registers to avoid picking up
+        * stale state.
+        *
+        * This must be done even when the task is still the owner
+        * as the registers may have been modified via ptrace()
+        * (not perfmon) by the previous task.
+        */
+       if (ctx->ctx_fl_using_dbreg) {
+               pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
+               pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
+       }
+
+       /*
+        * retrieved saved psr.up
+        */
+       psr_up = ctx->ctx_saved_psr_up;
+       need_irq_resend = pmu_conf->flags & PFM_PMU_IRQ_RESEND;
+
+       /*
+        * short path, our state is still there, just
+        * need to restore psr and we go
+        *
+        * we do not touch either PMC nor PMD. the psr is not touched
+        * by the overflow_handler. So we are safe w.r.t. to interrupt
+        * concurrency even without interrupt masking.
+        */
+       if (likely(owner == task)) {
+               if (likely(psr_up)) pfm_set_psr_up();
+               return;
+       }
+
+       /*
+        * someone else is still using the PMU, first push it out and
+        * then we'll be able to install our stuff !
+        *
+        * Upon return, there will be no owner for the current PMU
+        */
+       if (owner) pfm_lazy_save_regs(owner);
+
+       /*
+        * To avoid leaking information to the user level when psr.sp=0,
+        * we must reload ALL implemented pmds (even the ones we don't use).
+        * In the kernel we only allow PFM_READ_PMDS on registers which
+        * we initialized or requested (sampling) so there is no risk there.
+        */
+       pmd_mask = pfm_sysctl.fastctxsw ?  ctx->ctx_used_pmds[0] : 
ctx->ctx_all_pmds[0];
+
+       /*
+        * ALL accessible PMCs are systematically reloaded, unused registers
+        * get their default (from pfm_reset_pmu_state()) values to avoid 
picking
+        * up stale configuration.
+        *
+        * PMC0 is never in the mask. It is always restored separately
+        */
+       pmc_mask = ctx->ctx_all_pmcs[0];
+
+       pfm_restore_pmds(t->pmds, pmd_mask);
+       pfm_restore_pmcs(t->pmcs, pmc_mask);
+
+       /*
+        * check for pending overflow at the time the state
+        * was saved.
+        */
+       if (unlikely(PMC0_HAS_OVFL(t->pmcs[0]))) {
+               /*
+                * reload pmc0 with the overflow information
+                * On McKinley PMU, this will trigger a PMU interrupt
+                */
+               ia64_set_pmc(0, t->pmcs[0]);
+               ia64_srlz_d();
+
+               t->pmcs[0] = 0UL;
+
+               /*
+                * will replay the PMU interrupt
+                */
+               if (need_irq_resend) hw_resend_irq(NULL, IA64_PERFMON_VECTOR);
+
+               pfm_stats[smp_processor_id()].pfm_replay_ovfl_intr_count++;
+       }
+
+       /*
+        * establish new ownership. 
+        */
+       SET_PMU_OWNER(task, ctx);
+
+       /*
+        * restore the psr.up bit. measurement
+        * is active again.
+        * no PMU interrupt can happen at this point
+        * because we still have interrupts disabled.
+        */
+       if (likely(psr_up)) pfm_set_psr_up();
+}
+#endif /* CONFIG_SMP */
+
+/*
+ * this function assumes monitoring is stopped
+ */
+static void
+pfm_flush_pmds(struct task_struct *task, pfm_context_t *ctx)
+{
+       u64 pmc0;
+       unsigned long mask2, val, pmd_val, ovfl_val;
+       int i, can_access_pmu = 0;
+       int is_self;
+
+       /*
+        * is the caller the task being monitored (or which initiated the
+        * session for system wide measurements)
+        */
+       is_self = ctx->ctx_task == task ? 1 : 0;
+
+       /*
+        * can access PMU is task is the owner of the PMU state on the current 
CPU
+        * or if we are running on the CPU bound to the context in system-wide 
mode
+        * (that is not necessarily the task the context is attached to in this 
mode).
+        * In system-wide we always have can_access_pmu true because a task 
running on an
+        * invalid processor is flagged earlier in the call stack (see 
pfm_stop).
+        */
+       can_access_pmu = (GET_PMU_OWNER() == task) || (ctx->ctx_fl_system && 
ctx->ctx_cpu == smp_processor_id());
+       if (can_access_pmu) {
+               /*
+                * Mark the PMU as not owned
+                * This will cause the interrupt handler to do nothing in case 
an overflow
+                * interrupt was in-flight
+                * This also guarantees that pmc0 will contain the final state
+                * It virtually gives us full control on overflow processing 
from that point
+                * on.
+                */
+               SET_PMU_OWNER(NULL, NULL);
+               DPRINT(("releasing ownership\n"));
+
+               /*
+                * read current overflow status:
+                *
+                * we are guaranteed to read the final stable state
+                */
+               ia64_srlz_d();
+               pmc0 = ia64_get_pmc(0); /* slow */
+
+               /*
+                * reset freeze bit, overflow status information destroyed
+                */
+               pfm_unfreeze_pmu();
+       } else {
+               pmc0 = task->thread.pmcs[0];
+               /*
+                * clear whatever overflow status bits there were
+                */
+               task->thread.pmcs[0] = 0;
+       }
+       ovfl_val = pmu_conf->ovfl_val;
+       /*
+        * we save all the used pmds
+        * we take care of overflows for counting PMDs
+        *
+        * XXX: sampling situation is not taken into account here
+        */
+       mask2 = ctx->ctx_used_pmds[0];
+
+       DPRINT(("is_self=%d ovfl_val=0x%lx mask2=0x%lx\n", is_self, ovfl_val, 
mask2));
+
+       for (i = 0; mask2; i++, mask2>>=1) {
+
+               /* skip non used pmds */
+               if ((mask2 & 0x1) == 0) continue;
+
+               /*
+                * can access PMU always true in system wide mode
+                */
+               val = pmd_val = can_access_pmu ? ia64_get_pmd(i) : 
task->thread.pmds[i];
+
+               if (PMD_IS_COUNTING(i)) {
+                       DPRINT(("[%d] pmd[%d] ctx_pmd=0x%lx hw_pmd=0x%lx\n",
+                               task->pid,
+                               i,
+                               ctx->ctx_pmds[i].val,
+                               val & ovfl_val));
+
+                       /*
+                        * we rebuild the full 64 bit value of the counter
+                        */
+                       val = ctx->ctx_pmds[i].val + (val & ovfl_val);
+
+                       /*
+                        * now everything is in ctx_pmds[] and we need
+                        * to clear the saved context from save_regs() such that
+                        * pfm_read_pmds() gets the correct value
+                        */
+                       pmd_val = 0UL;
+
+                       /*
+                        * take care of overflow inline
+                        */
+                       if (pmc0 & (1UL << i)) {
+                               val += 1 + ovfl_val;
+                               DPRINT(("[%d] pmd[%d] overflowed\n", task->pid, 
i));
+                       }
+               }
+
+               DPRINT(("[%d] ctx_pmd[%d]=0x%lx  pmd_val=0x%lx\n", task->pid, 
i, val, pmd_val));
+
+               if (is_self) task->thread.pmds[i] = pmd_val;
+
+               ctx->ctx_pmds[i].val = val;
+       }
+}
+
+static struct irqaction perfmon_irqaction = {
+       .handler = pfm_interrupt_handler,
+       .flags   = SA_INTERRUPT,
+       .name    = "perfmon"
+};
+
+static void
+pfm_alt_save_pmu_state(void *data)
+{
+       struct pt_regs *regs;
+
+       regs = task_pt_regs(current);
+
+       DPRINT(("called\n"));
+
+       /*
+        * should not be necessary but
+        * let's take not risk
+        */
+       pfm_clear_psr_up();
+       pfm_clear_psr_pp();
+       ia64_psr(regs)->pp = 0;
+
+       /*
+        * This call is required
+        * May cause a spurious interrupt on some processors
+        */
+       pfm_freeze_pmu();
+
+       ia64_srlz_d();
+}
+
+void
+pfm_alt_restore_pmu_state(void *data)
+{
+       struct pt_regs *regs;
+
+       regs = task_pt_regs(current);
+
+       DPRINT(("called\n"));
+
+       /*
+        * put PMU back in state expected
+        * by perfmon
+        */
+       pfm_clear_psr_up();
+       pfm_clear_psr_pp();
+       ia64_psr(regs)->pp = 0;
+
+       /*
+        * perfmon runs with PMU unfrozen at all times
+        */
+       pfm_unfreeze_pmu();
+
+       ia64_srlz_d();
+}
+
+int
+pfm_install_alt_pmu_interrupt(pfm_intr_handler_desc_t *hdl)
+{
+       int ret, i;
+       int reserve_cpu;
+
+       /* some sanity checks */
+       if (hdl == NULL || hdl->handler == NULL) return -EINVAL;
+
+       /* do the easy test first */
+       if (pfm_alt_intr_handler) return -EBUSY;
+
+       /* one at a time in the install or remove, just fail the others */
+       if (!spin_trylock(&pfm_alt_install_check)) {
+               return -EBUSY;
+       }
+
+       /* reserve our session */
+       for_each_online_cpu(reserve_cpu) {
+               ret = pfm_reserve_session(NULL, 1, reserve_cpu);
+               if (ret) goto cleanup_reserve;
+       }
+
+       /* save the current system wide pmu states */
+       ret = on_each_cpu(pfm_alt_save_pmu_state, NULL, 0, 1);
+       if (ret) {
+               DPRINT(("on_each_cpu() failed: %d\n", ret));
+               goto cleanup_reserve;
+       }
+
+       /* officially change to the alternate interrupt handler */
+       pfm_alt_intr_handler = hdl;
+
+       spin_unlock(&pfm_alt_install_check);
+
+       return 0;
+
+cleanup_reserve:
+       for_each_online_cpu(i) {
+               /* don't unreserve more than we reserved */
+               if (i >= reserve_cpu) break;
+
+               pfm_unreserve_session(NULL, 1, i);
+       }
+
+       spin_unlock(&pfm_alt_install_check);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(pfm_install_alt_pmu_interrupt);
+
+int
+pfm_remove_alt_pmu_interrupt(pfm_intr_handler_desc_t *hdl)
+{
+       int i;
+       int ret;
+
+       if (hdl == NULL) return -EINVAL;
+
+       /* cannot remove someone else's handler! */
+       if (pfm_alt_intr_handler != hdl) return -EINVAL;
+
+       /* one at a time in the install or remove, just fail the others */
+       if (!spin_trylock(&pfm_alt_install_check)) {
+               return -EBUSY;
+       }
+
+       pfm_alt_intr_handler = NULL;
+
+       ret = on_each_cpu(pfm_alt_restore_pmu_state, NULL, 0, 1);
+       if (ret) {
+               DPRINT(("on_each_cpu() failed: %d\n", ret));
+       }
+
+       for_each_online_cpu(i) {
+               pfm_unreserve_session(NULL, 1, i);
+       }
+
+       spin_unlock(&pfm_alt_install_check);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(pfm_remove_alt_pmu_interrupt);
+
+/*
+ * perfmon initialization routine, called from the initcall() table
+ */
+static int init_pfm_fs(void);
+
+static int __init
+pfm_probe_pmu(void)
+{
+       pmu_config_t **p;
+       int family;
+
+       family = local_cpu_data->family;
+       p      = pmu_confs;
+
+       while(*p) {
+               if ((*p)->probe) {
+                       if ((*p)->probe() == 0) goto found;
+               } else if ((*p)->pmu_family == family || (*p)->pmu_family == 
0xff) {
+                       goto found;
+               }
+               p++;
+       }
+       return -1;
+found:
+       pmu_conf = *p;
+       return 0;
+}
+
+static struct file_operations pfm_proc_fops = {
+       .open           = pfm_proc_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = seq_release,
+};
+
+int __init
+pfm_init(void)
+{
+       unsigned int n, n_counters, i;
+
+       printk("perfmon: version %u.%u IRQ %u\n",
+               PFM_VERSION_MAJ,
+               PFM_VERSION_MIN,
+               IA64_PERFMON_VECTOR);
+
+       if (pfm_probe_pmu()) {
+               printk(KERN_INFO "perfmon: disabled, there is no support for 
processor family %d\n", 
+                               local_cpu_data->family);
+               return -ENODEV;
+       }
+
+       /*
+        * compute the number of implemented PMD/PMC from the
+        * description tables
+        */
+       n = 0;
+       for (i=0; PMC_IS_LAST(i) == 0;  i++) {
+               if (PMC_IS_IMPL(i) == 0) continue;
+               pmu_conf->impl_pmcs[i>>6] |= 1UL << (i&63);
+               n++;
+       }
+       pmu_conf->num_pmcs = n;
+
+       n = 0; n_counters = 0;
+       for (i=0; PMD_IS_LAST(i) == 0;  i++) {
+               if (PMD_IS_IMPL(i) == 0) continue;
+               pmu_conf->impl_pmds[i>>6] |= 1UL << (i&63);
+               n++;
+               if (PMD_IS_COUNTING(i)) n_counters++;
+       }
+       pmu_conf->num_pmds      = n;
+       pmu_conf->num_counters  = n_counters;
+
+       /*
+        * sanity checks on the number of debug registers
+        */
+       if (pmu_conf->use_rr_dbregs) {
+               if (pmu_conf->num_ibrs > IA64_NUM_DBG_REGS) {
+                       printk(KERN_INFO "perfmon: unsupported number of code 
debug registers (%u)\n", pmu_conf->num_ibrs);
+                       pmu_conf = NULL;
+                       return -1;
+               }
+               if (pmu_conf->num_dbrs > IA64_NUM_DBG_REGS) {
+                       printk(KERN_INFO "perfmon: unsupported number of data 
debug registers (%u)\n", pmu_conf->num_ibrs);
+                       pmu_conf = NULL;
+                       return -1;
+               }
+       }
+
+       printk("perfmon: %s PMU detected, %u PMCs, %u PMDs, %u counters (%lu 
bits)\n",
+              pmu_conf->pmu_name,
+              pmu_conf->num_pmcs,
+              pmu_conf->num_pmds,
+              pmu_conf->num_counters,
+              ffz(pmu_conf->ovfl_val));
+
+       /* sanity check */
+       if (pmu_conf->num_pmds >= IA64_NUM_PMD_REGS || pmu_conf->num_pmcs >= 
IA64_NUM_PMC_REGS) {
+               printk(KERN_ERR "perfmon: not enough pmc/pmd, perfmon 
disabled\n");
+               pmu_conf = NULL;
+               return -1;
+       }
+
+       /*
+        * create /proc/perfmon (mostly for debugging purposes)
+        */
+       perfmon_dir = create_proc_entry("perfmon", S_IRUGO, NULL);
+       if (perfmon_dir == NULL) {
+               printk(KERN_ERR "perfmon: cannot create /proc entry, perfmon 
disabled\n");
+               pmu_conf = NULL;
+               return -1;
+       }
+       /*
+        * install customized file operations for /proc/perfmon entry
+        */
+       perfmon_dir->proc_fops = &pfm_proc_fops;
+
+       /*
+        * create /proc/sys/kernel/perfmon (for debugging purposes)
+        */
+       pfm_sysctl_header = register_sysctl_table(pfm_sysctl_root, 0);
+
+       /*
+        * initialize all our spinlocks
+        */
+       spin_lock_init(&pfm_sessions.pfs_lock);
+       spin_lock_init(&pfm_buffer_fmt_lock);
+
+       init_pfm_fs();
+
+       for(i=0; i < NR_CPUS; i++) pfm_stats[i].pfm_ovfl_intr_cycles_min = ~0UL;
+
+       return 0;
+}
+
+__initcall(pfm_init);
+
+/*
+ * this function is called before pfm_init()
+ */
+void
+pfm_init_percpu (void)
+{
+       /*
+        * make sure no measurement is active
+        * (may inherit programmed PMCs from EFI).
+        */
+       pfm_clear_psr_pp();
+       pfm_clear_psr_up();
+
+       /*
+        * we run with the PMU not frozen at all times
+        */
+       pfm_unfreeze_pmu();
+
+       if (smp_processor_id() == 0)
+               register_percpu_irq(IA64_PERFMON_VECTOR, &perfmon_irqaction);
+
+       ia64_setreg(_IA64_REG_CR_PMV, IA64_PERFMON_VECTOR);
+       ia64_srlz_d();
+}
+
+/*
+ * used for debug purposes only
+ */
+void
+dump_pmu_state(const char *from)
+{
+       struct task_struct *task;
+       struct thread_struct *t;
+       struct pt_regs *regs;
+       pfm_context_t *ctx;
+       unsigned long psr, dcr, info, flags;
+       int i, this_cpu;
+
+       local_irq_save(flags);
+
+       this_cpu = smp_processor_id();
+       regs     = task_pt_regs(current);
+       info     = PFM_CPUINFO_GET();
+       dcr      = ia64_getreg(_IA64_REG_CR_DCR);
+
+       if (info == 0 && ia64_psr(regs)->pp == 0 && (dcr & IA64_DCR_PP) == 0) {
+               local_irq_restore(flags);
+               return;
+       }
+
+       printk("CPU%d from %s() current [%d] iip=0x%lx %s\n", 
+               this_cpu, 
+               from, 
+               current->pid, 
+               regs->cr_iip,
+               current->comm);
+
+       task = GET_PMU_OWNER();
+       ctx  = GET_PMU_CTX();
+
+       printk("->CPU%d owner [%d] ctx=%p\n", this_cpu, task ? task->pid : -1, 
ctx);
+
+       psr = pfm_get_psr();
+
+       printk("->CPU%d pmc0=0x%lx psr.pp=%d psr.up=%d dcr.pp=%d 
syst_info=0x%lx user_psr.up=%d user_psr.pp=%d\n", 
+               this_cpu,
+               ia64_get_pmc(0),
+               psr & IA64_PSR_PP ? 1 : 0,
+               psr & IA64_PSR_UP ? 1 : 0,
+               dcr & IA64_DCR_PP ? 1 : 0,
+               info,
+               ia64_psr(regs)->up,
+               ia64_psr(regs)->pp);
+
+       ia64_psr(regs)->up = 0;
+       ia64_psr(regs)->pp = 0;
+
+       t = &current->thread;
+
+       for (i=1; PMC_IS_LAST(i) == 0; i++) {
+               if (PMC_IS_IMPL(i) == 0) continue;
+               printk("->CPU%d pmc[%d]=0x%lx thread_pmc[%d]=0x%lx\n", 
this_cpu, i, ia64_get_pmc(i), i, t->pmcs[i]);
+       }
+
+       for (i=1; PMD_IS_LAST(i) == 0; i++) {
+               if (PMD_IS_IMPL(i) == 0) continue;
+               printk("->CPU%d pmd[%d]=0x%lx thread_pmd[%d]=0x%lx\n", 
this_cpu, i, ia64_get_pmd(i), i, t->pmds[i]);
+       }
+
+       if (ctx) {
+               printk("->CPU%d ctx_state=%d vaddr=%p addr=%p fd=%d 
ctx_task=[%d] saved_psr_up=0x%lx\n",
+                               this_cpu,
+                               ctx->ctx_state,
+                               ctx->ctx_smpl_vaddr,
+                               ctx->ctx_smpl_hdr,
+                               ctx->ctx_msgq_head,
+                               ctx->ctx_msgq_tail,
+                               ctx->ctx_saved_psr_up);
+       }
+       local_irq_restore(flags);
+}
+
+/*
+ * called from process.c:copy_thread(). task is new child.
+ */
+void
+pfm_inherit(struct task_struct *task, struct pt_regs *regs)
+{
+       struct thread_struct *thread;
+
+       DPRINT(("perfmon: pfm_inherit clearing state for [%d]\n", task->pid));
+
+       thread = &task->thread;
+
+       /*
+        * cut links inherited from parent (current)
+        */
+       thread->pfm_context = NULL;
+
+       PFM_SET_WORK_PENDING(task, 0);
+
+       /*
+        * the psr bits are already set properly in copy_threads()
+        */
+}
+#else  /* !CONFIG_PERFMON */
+asmlinkage long
+sys_perfmonctl (int fd, int cmd, void *arg, int count)
+{
+       return -ENOSYS;
+}
+#endif /* CONFIG_PERFMON */
diff -r 6cfe32a69ac6 -r da51aee40456 
linux-2.6-xen-sparse/arch/ia64/oprofile/Makefile
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/linux-2.6-xen-sparse/arch/ia64/oprofile/Makefile  Tue Nov 28 11:19:40 
2006 -0700
@@ -0,0 +1,10 @@
+obj-$(CONFIG_OPROFILE) += oprofile.o
+
+DRIVER_OBJS := $(addprefix ../../../drivers/oprofile/, \
+               oprof.o cpu_buffer.o buffer_sync.o \
+               event_buffer.o oprofile_files.o \
+               oprofilefs.o oprofile_stats.o \
+               timer_int.o )
+
+oprofile-y := $(DRIVER_OBJS) init.o backtrace.o
+oprofile-$(CONFIG_PERFMON) += perfmon.o
diff -r 6cfe32a69ac6 -r da51aee40456 
linux-2.6-xen-sparse/arch/ia64/oprofile/init.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/linux-2.6-xen-sparse/arch/ia64/oprofile/init.c    Tue Nov 28 11:19:40 
2006 -0700
@@ -0,0 +1,38 @@
+/**
+ * @file init.c
+ *
+ * @remark Copyright 2002 OProfile authors
+ * @remark Read the file COPYING
+ *
+ * @author John Levon <levon@xxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/kernel.h>
+#include <linux/oprofile.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+ 
+extern int perfmon_init(struct oprofile_operations * ops);
+extern void perfmon_exit(void);
+extern void ia64_backtrace(struct pt_regs * const regs, unsigned int depth);
+
+int __init oprofile_arch_init(struct oprofile_operations * ops)
+{
+       int ret = -ENODEV;
+
+#ifdef CONFIG_PERFMON
+       /* perfmon_init() can fail, but we have no way to report it */
+       ret = perfmon_init(ops);
+#endif
+       ops->backtrace = ia64_backtrace;
+
+       return ret;
+}
+
+
+void oprofile_arch_exit(void)
+{
+#ifdef CONFIG_PERFMON
+       perfmon_exit();
+#endif
+}
diff -r 6cfe32a69ac6 -r da51aee40456 
linux-2.6-xen-sparse/arch/ia64/oprofile/perfmon.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/linux-2.6-xen-sparse/arch/ia64/oprofile/perfmon.c Tue Nov 28 11:19:40 
2006 -0700
@@ -0,0 +1,100 @@
+/**
+ * @file perfmon.c
+ *
+ * @remark Copyright 2003 OProfile authors
+ * @remark Read the file COPYING
+ *
+ * @author John Levon <levon@xxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/kernel.h>
+#include <linux/config.h>
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <asm/perfmon.h>
+#include <asm/ptrace.h>
+#include <asm/errno.h>
+
+static int allow_ints;
+
+static int
+perfmon_handler(struct task_struct *task, void *buf, pfm_ovfl_arg_t *arg,
+                struct pt_regs *regs, unsigned long stamp)
+{
+       int event = arg->pmd_eventid;
+ 
+       arg->ovfl_ctrl.bits.reset_ovfl_pmds = 1;
+
+       /* the owner of the oprofile event buffer may have exited
+        * without perfmon being shutdown (e.g. SIGSEGV)
+        */
+       if (allow_ints)
+               oprofile_add_sample(regs, event);
+       return 0;
+}
+
+
+static int perfmon_start(void)
+{
+       allow_ints = 1;
+       return 0;
+}
+
+
+static void perfmon_stop(void)
+{
+       allow_ints = 0;
+}
+
+
+#define OPROFILE_FMT_UUID { \
+       0x77, 0x7a, 0x6e, 0x61, 0x20, 0x65, 0x73, 0x69, 0x74, 0x6e, 0x72, 0x20, 
0x61, 0x65, 0x0a, 0x6c }
+
+static pfm_buffer_fmt_t oprofile_fmt = {
+       .fmt_name           = "oprofile_format",
+       .fmt_uuid           = OPROFILE_FMT_UUID,
+       .fmt_handler        = perfmon_handler,
+};
+
+
+static char * get_cpu_type(void)
+{
+       __u8 family = local_cpu_data->family;
+
+       switch (family) {
+               case 0x07:
+                       return "ia64/itanium";
+               case 0x1f:
+                       return "ia64/itanium2";
+               default:
+                       return "ia64/ia64";
+       }
+}
+
+
+/* all the ops are handled via userspace for IA64 perfmon */
+
+static int using_perfmon;
+
+int perfmon_init(struct oprofile_operations * ops)
+{
+       int ret = pfm_register_buffer_fmt(&oprofile_fmt);
+       if (ret)
+               return -ENODEV;
+
+       ops->cpu_type = get_cpu_type();
+       ops->start = perfmon_start;
+       ops->stop = perfmon_stop;
+       using_perfmon = 1;
+       printk(KERN_INFO "oprofile: using perfmon.\n");
+       return 0;
+}
+
+
+void perfmon_exit(void)
+{
+       if (!using_perfmon)
+               return;
+
+       pfm_unregister_buffer_fmt(oprofile_fmt.fmt_uuid);
+}

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