[Xen-changelog] [linux-2.6.18-xen] Add backtrace support to xenoprof.

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1181220507 -3600
# Node ID 56b6e11f15fe2db18c5d4992124a273c781d894b
# Parent  85b046c1da186089a6069b4d0f879ea7c32c4c42
Add backtrace support to xenoprof.
Signed-off-by: Amitabha Roy <amitabha.roy@xxxxxxxxx>
Reviewed-by: Jose Renato G Santos <joserenato.santos@xxxxxx>
---
 drivers/xen/xenoprof/xenoprofile.c |  102 ++++++++++++++++++++++++++-----------
 1 files changed, 73 insertions(+), 29 deletions(-)

diff -r 85b046c1da18 -r 56b6e11f15fe drivers/xen/xenoprof/xenoprofile.c
--- a/drivers/xen/xenoprof/xenoprofile.c        Thu Jun 07 11:11:13 2007 +0100
+++ b/drivers/xen/xenoprof/xenoprofile.c        Thu Jun 07 13:48:27 2007 +0100
@@ -51,11 +51,13 @@ static int xenoprof_is_primary = 0;
 static int xenoprof_is_primary = 0;
 static int active_defined;
 
+extern unsigned long backtrace_depth;
+
 /* Number of buffers in shared area (one per VCPU) */
 int nbuf;
 /* Mappings of VIRQ_XENOPROF to irq number (per cpu) */
 int ovf_irq[NR_CPUS];
-/* cpu model type string - copied from Xen memory space on XENOPROF_init 
command */
+/* cpu model type string - copied from Xen on XENOPROF_init command */
 char cpu_type[XENOPROF_CPU_TYPE_SIZE];
 
 #ifdef CONFIG_PM
@@ -115,38 +117,54 @@ unsigned int pdomains;
 unsigned int pdomains;
 struct xenoprof_passive passive_domains[MAX_OPROF_DOMAINS];
 
+/* Check whether the given entry is an escape code */
+static int xenoprof_is_escape(xenoprof_buf_t * buf, int tail)
+{
+       return (buf->event_log[tail].eip == XENOPROF_ESCAPE_CODE);
+}
+
+/* Get the event at the given entry  */
+static uint8_t xenoprof_get_event(xenoprof_buf_t * buf, int tail)
+{
+       return (buf->event_log[tail].event);
+}
+
 static void xenoprof_add_pc(xenoprof_buf_t *buf, int is_passive)
 {
        int head, tail, size;
+       int tracing = 0;
 
        head = buf->event_head;
        tail = buf->event_tail;
        size = buf->event_size;
 
-       if (tail > head) {
-               while (tail < size) {
-                       oprofile_add_pc(buf->event_log[tail].eip,
-                                       buf->event_log[tail].mode,
-                                       buf->event_log[tail].event);
+       while (tail != head) {
+               if (xenoprof_is_escape(buf, tail) &&
+                   xenoprof_get_event(buf, tail) == XENOPROF_TRACE_BEGIN) {
+                       tracing=1;
+                       oprofile_add_pc(ESCAPE_CODE, buf->event_log[tail].mode, 
+                                       CPU_TRACE_BEGIN); 
                        if (!is_passive)
                                oprofile_samples++;
                        else
                                p_oprofile_samples++;
-                       tail++;
-               }
-               tail = 0;
-       }
-       while (tail < head) {
-               oprofile_add_pc(buf->event_log[tail].eip,
-                               buf->event_log[tail].mode,
-                               buf->event_log[tail].event);
-               if (!is_passive)
-                       oprofile_samples++;
-               else
-                       p_oprofile_samples++;
+                       
+               } else {
+                       oprofile_add_pc(buf->event_log[tail].eip,
+                                       buf->event_log[tail].mode,
+                                       buf->event_log[tail].event);
+                       if (!tracing) {
+                               if (!is_passive)
+                                       oprofile_samples++;
+                               else
+                                       p_oprofile_samples++;
+                       }
+       
+               }
                tail++;
-       }
-
+               if(tail==size)
+                   tail=0;
+       }
        buf->event_tail = tail;
 }
 
@@ -162,8 +180,8 @@ static void xenoprof_handle_passive(void
                        if (buf->event_head == buf->event_tail)
                                continue;
                        if (!flag_domain) {
-                               if 
(!oprofile_add_domain_switch(passive_domains[i].
-                                                               domain_id))
+                               if (!oprofile_add_domain_switch(
+                                       passive_domains[i].domain_id))
                                        goto done;
                                flag_domain = 1;
                        }
@@ -284,22 +302,31 @@ static int xenoprof_setup(void)
                /* Define dom0 as an active domain if not done yet */
                if (!active_defined) {
                        domid_t domid;
-                       ret = 
HYPERVISOR_xenoprof_op(XENOPROF_reset_active_list, NULL);
+                       ret = HYPERVISOR_xenoprof_op(
+                               XENOPROF_reset_active_list, NULL);
                        if (ret)
                                goto err;
                        domid = 0;
-                       ret = HYPERVISOR_xenoprof_op(XENOPROF_set_active, 
&domid);
+                       ret = HYPERVISOR_xenoprof_op(
+                               XENOPROF_set_active, &domid);
                        if (ret)
                                goto err;
                        active_defined = 1;
                }
 
+               if (backtrace_depth > 0) {
+                       ret = HYPERVISOR_xenoprof_op(XENOPROF_set_backtrace, 
+                                                    &backtrace_depth);
+                       if (ret)
+                               backtrace_depth = 0;
+               }
+
                ret = HYPERVISOR_xenoprof_op(XENOPROF_reserve_counters, NULL);
                if (ret)
                        goto err;
+               
                xenoprof_arch_counter();
                ret = HYPERVISOR_xenoprof_op(XENOPROF_setup_events, NULL);
-
                if (ret)
                        goto err;
        }
@@ -425,7 +452,8 @@ static int xenoprof_set_passive(int * p_
                        goto out;
                for (j = 0; j < passive_domains[i].nbuf; j++) {
                        buf = (struct xenoprof_buf *)
-                               &p_shared_buffer[i].buffer[j * 
passive_domains[i].bufsize];
+                               &p_shared_buffer[i].buffer[
+                               j * passive_domains[i].bufsize];
                        BUG_ON(buf->vcpu_id >= MAX_VIRT_CPUS);
                        p_xenoprof_buf[i][buf->vcpu_id] = buf;
                }
@@ -438,8 +466,22 @@ out:
        for (j = 0; j < i; j++)
                xenoprof_arch_unmap_shared_buffer(&p_shared_buffer[i]);
 
-       return ret;
-}
+       return ret;
+}
+
+
+/* The dummy backtrace function to keep oprofile happy
+ * The real backtrace is done in xen
+ */
+static void xenoprof_dummy_backtrace(struct pt_regs * const regs, 
+                                    unsigned int depth)
+{
+       /* this should never be called */
+       BUG();
+       return;
+}
+
+
 
 struct oprofile_operations xenoprof_ops = {
 #ifdef HAVE_XENOPROF_CREATE_FILES
@@ -450,7 +492,8 @@ struct oprofile_operations xenoprof_ops 
        .setup          = xenoprof_setup,
        .shutdown       = xenoprof_shutdown,
        .start          = xenoprof_start,
-       .stop           = xenoprof_stop
+       .stop           = xenoprof_stop,
+       .backtrace      = xenoprof_dummy_backtrace
 };
 
 
@@ -481,6 +524,7 @@ int __init xenoprofile_init(struct oprof
 
                active_defined = 0;
        }
+
        printk(KERN_INFO "%s: ret %d, events %d, xenoprof_is_primary %d\n",
               __func__, ret, init.num_events, xenoprof_is_primary);
        return ret;

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