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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] Add a compile time option to enable domain 0 running in ring 0.
# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID ee8041b0ab86f9315476f718da57af38cbf2eed7
# Parent 6060937db0fe568d34b83d015ebe22b86194faa9
Add a compile time option to enable domain 0 running in ring 0.
In this mode only a single guest kernel is supported.
This mode only works for x86/32 (not x86/64).
Signed-off-by: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/Makefile
--- a/xen/arch/x86/Makefile Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/Makefile Mon Feb 27 14:52:43 2006
@@ -31,6 +31,10 @@
else
OBJS += shadow32.o # x86_32: old code
endif
+endif
+
+ifneq ($(supervisor_mode_kernel),y)
+OBJS := $(subst x86_32/supervisor_mode_kernel.o,,$(OBJS))
endif
OBJS := $(subst $(TARGET_SUBARCH)/asm-offsets.o,,$(OBJS))
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/Rules.mk
--- a/xen/arch/x86/Rules.mk Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/Rules.mk Mon Feb 27 14:52:43 2006
@@ -6,6 +6,7 @@
# 'make clean' before rebuilding.
#
pae ?= n
+supervisor_mode_kernel ?= n
CFLAGS += -nostdinc -fno-builtin -fno-common -fno-strict-aliasing
CFLAGS += -iwithprefix include -Wall -Werror -Wno-pointer-arith -pipe
@@ -32,6 +33,9 @@
CFLAGS += -DCONFIG_X86_PAE=1
endif
endif
+ifeq ($(supervisor_mode_kernel),y)
+CFLAGS += -DCONFIG_X86_SUPERVISOR_MODE_KERNEL=1
+endif
ifeq ($(TARGET_SUBARCH),x86_64)
CFLAGS += -m64 -mno-red-zone -fpic -fno-reorder-blocks
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/domain.c Mon Feb 27 14:52:43 2006
@@ -351,17 +351,17 @@
if ( !(c->flags & VGCF_HVM_GUEST) )
{
- fixup_guest_selector(c->user_regs.ss);
- fixup_guest_selector(c->kernel_ss);
- fixup_guest_selector(c->user_regs.cs);
+ fixup_guest_stack_selector(c->user_regs.ss);
+ fixup_guest_stack_selector(c->kernel_ss);
+ fixup_guest_code_selector(c->user_regs.cs);
#ifdef __i386__
- fixup_guest_selector(c->event_callback_cs);
- fixup_guest_selector(c->failsafe_callback_cs);
+ fixup_guest_code_selector(c->event_callback_cs);
+ fixup_guest_code_selector(c->failsafe_callback_cs);
#endif
for ( i = 0; i < 256; i++ )
- fixup_guest_selector(c->trap_ctxt[i].cs);
+ fixup_guest_code_selector(c->trap_ctxt[i].cs);
}
else if ( !hvm_enabled )
return -EINVAL;
@@ -847,7 +847,11 @@
regs = guest_cpu_user_regs();
#if defined(__i386__)
regs->eax = op;
- regs->eip -= 2; /* re-execute 'int 0x82' */
+
+ if ( supervisor_mode_kernel )
+ regs->eip &= ~31; /* re-execute entire hypercall entry stub */
+ else
+ regs->eip -= 2; /* re-execute 'int 0x82' */
for ( i = 0; i < nr_args; i++ )
{
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/domain_build.c
--- a/xen/arch/x86/domain_build.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/domain_build.c Mon Feb 27 14:52:43 2006
@@ -793,6 +793,17 @@
update_pagetables(v);
}
+ if ( supervisor_mode_kernel )
+ {
+ v->arch.guest_context.kernel_ss &= ~3;
+ v->arch.guest_context.user_regs.ss &= ~3;
+ v->arch.guest_context.user_regs.es &= ~3;
+ v->arch.guest_context.user_regs.ds &= ~3;
+ v->arch.guest_context.user_regs.fs &= ~3;
+ v->arch.guest_context.user_regs.gs &= ~3;
+ printk("Dom0 runs in ring 0 (supervisor mode)\n");
+ }
+
rc = 0;
/* DOM0 is permitted full I/O capabilities. */
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/traps.c Mon Feb 27 14:52:43 2006
@@ -1429,7 +1429,7 @@
if ( cur.address == 0 )
break;
- fixup_guest_selector(cur.cs);
+ fixup_guest_code_selector(cur.cs);
memcpy(&dst[cur.vector], &cur, sizeof(cur));
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/x86_32/asm-offsets.c
--- a/xen/arch/x86/x86_32/asm-offsets.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/x86_32/asm-offsets.c Mon Feb 27 14:52:43 2006
@@ -72,6 +72,13 @@
DEFINE(_VCPUF_nmi_masked, _VCPUF_nmi_masked);
BLANK();
+ OFFSET(TSS_ss0, struct tss_struct, ss0);
+ OFFSET(TSS_esp0, struct tss_struct, esp0);
+ OFFSET(TSS_ss1, struct tss_struct, ss1);
+ OFFSET(TSS_esp1, struct tss_struct, esp1);
+ DEFINE(TSS_sizeof, sizeof(struct tss_struct));
+ BLANK();
+
OFFSET(VCPU_svm_vmcb_pa, struct vcpu, arch.hvm_svm.vmcb_pa);
OFFSET(VCPU_svm_hsa_pa, struct vcpu, arch.hvm_svm.host_save_pa);
OFFSET(VCPU_svm_vmcb, struct vcpu, arch.hvm_svm.vmcb);
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/x86_32/entry.S
--- a/xen/arch/x86/x86_32/entry.S Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/x86_32/entry.S Mon Feb 27 14:52:43 2006
@@ -77,6 +77,13 @@
restore_all_guest:
testl $X86_EFLAGS_VM,UREGS_eflags(%esp)
jnz restore_all_vm86
+#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL
+ testl $2,UREGS_cs(%esp)
+ jnz 1f
+ call restore_ring0_guest
+ jmp restore_all_vm86
+1:
+#endif
FLT1: mov UREGS_ds(%esp),%ds
FLT2: mov UREGS_es(%esp),%es
FLT3: mov UREGS_fs(%esp),%fs
@@ -157,6 +164,7 @@
ALIGN
ENTRY(hypercall)
subl $4,%esp
+ FIXUP_RING0_GUEST_STACK
SAVE_ALL(b)
sti
GET_CURRENT(%ebx)
@@ -294,6 +302,11 @@
popl %eax
shll $16,%eax # Bits 16-23: saved_upcall_mask
movw UREGS_cs+4(%esp),%ax # Bits 0-15: CS
+#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL
+ testw $2,%ax
+ jnz FLT15
+ and $~3,%ax # RPL 1 -> RPL 0
+#endif
FLT15: movl %eax,%gs:4(%esi)
test $0x00FF0000,%eax # Bits 16-23: saved_upcall_mask
setz %ch # %ch == !saved_upcall_mask
@@ -388,6 +401,7 @@
pushl $TRAP_divide_error<<16
ALIGN
error_code:
+ FIXUP_RING0_GUEST_STACK
SAVE_ALL_NOSEGREGS(a)
SET_XEN_SEGMENTS(a)
testb $X86_EFLAGS_IF>>8,UREGS_eflags+1(%esp)
@@ -505,6 +519,10 @@
jmp error_code
ENTRY(nmi)
+#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL
+ # NMI entry protocol is incompatible with guest kernel in ring 0.
+ iret
+#else
# Save state but do not trash the segment registers!
# We may otherwise be unable to reload them or copy them to ring 1.
pushl %eax
@@ -546,6 +564,7 @@
movl $(APIC_DM_FIXED | APIC_DEST_SELF | APIC_DEST_LOGICAL | \
TRAP_deferred_nmi),%ss:APIC_ICR(%eax)
jmp restore_all_xen
+#endif /* !CONFIG_X86_SUPERVISOR_MODE_KERNEL */
ENTRY(setup_vm86_frame)
# Copies the entire stack frame forwards by 16 bytes.
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/x86_32/mm.c
--- a/xen/arch/x86/x86_32/mm.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/x86_32/mm.c Mon Feb 27 14:52:43 2006
@@ -180,6 +180,15 @@
page_set_owner(page, dom_xen);
}
}
+
+ if ( supervisor_mode_kernel )
+ {
+ /* Guest kernel runs in ring 0, not ring 1. */
+ struct desc_struct *d;
+ d = &gdt_table[(FLAT_RING1_CS >> 3) - FIRST_RESERVED_GDT_ENTRY];
+ d[0].b &= ~_SEGMENT_DPL;
+ d[1].b &= ~_SEGMENT_DPL;
+ }
}
long subarch_memory_op(int op, void *arg)
@@ -223,7 +232,7 @@
int nr = smp_processor_id();
struct tss_struct *t = &init_tss[nr];
- fixup_guest_selector(ss);
+ fixup_guest_stack_selector(ss);
current->arch.guest_context.kernel_ss = ss;
current->arch.guest_context.kernel_sp = esp;
@@ -239,6 +248,10 @@
unsigned long base, limit;
u32 a = d->a, b = d->b;
u16 cs;
+
+ /* Let a ring0 guest kernel set any descriptor it wants to. */
+ if ( supervisor_mode_kernel )
+ return 1;
/* A not-present descriptor will always fault, so is safe. */
if ( !(b & _SEGMENT_P) )
@@ -273,7 +286,7 @@
/* Validate and fix up the target code selector. */
cs = a >> 16;
- fixup_guest_selector(cs);
+ fixup_guest_code_selector(cs);
if ( !guest_gate_selector_okay(cs) )
goto bad;
a = d->a = (d->a & 0xffffU) | (cs << 16);
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/x86_32/traps.c
--- a/xen/arch/x86/x86_32/traps.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/x86_32/traps.c Mon Feb 27 14:52:43 2006
@@ -256,8 +256,14 @@
* We can't virtualise interrupt gates, as there's no way to get
* the CPU to automatically clear the events_mask variable. Also we
* must ensure that the CS is safe to poke into an interrupt gate.
- */
- if ( TI_GET_IF(ti) || !guest_gate_selector_okay(ti->cs) )
+ *
+ * When running with supervisor_mode_kernel enabled a direct trap
+ * to the guest OS cannot be used because the INT instruction will
+ * switch to the Xen stack and we need to swap back to the guest
+ * kernel stack before passing control to the system call entry point.
+ */
+ if ( TI_GET_IF(ti) || !guest_gate_selector_okay(ti->cs) ||
+ supervisor_mode_kernel )
{
v->arch.int80_desc.a = v->arch.int80_desc.b = 0;
return;
@@ -278,8 +284,8 @@
{
struct vcpu *d = current;
- fixup_guest_selector(event_selector);
- fixup_guest_selector(failsafe_selector);
+ fixup_guest_code_selector(event_selector);
+ fixup_guest_code_selector(failsafe_selector);
d->arch.guest_context.event_callback_cs = event_selector;
d->arch.guest_context.event_callback_eip = event_address;
@@ -289,12 +295,51 @@
return 0;
}
-void hypercall_page_initialise(void *hypercall_page)
-{
+static void hypercall_page_initialise_ring0_kernel(void *hypercall_page)
+{
+ extern asmlinkage int hypercall(void);
char *p;
int i;
/* Fill in all the transfer points with template machine code. */
+
+ for ( i = 0; i < NR_hypercalls; i++ )
+ {
+ p = (char *)(hypercall_page + (i * 32));
+
+ *(u8 *)(p+ 0) = 0x9c; /* pushf */
+ *(u8 *)(p+ 1) = 0xfa; /* cli */
+ *(u8 *)(p+ 2) = 0xb8; /* mov $<i>,%eax */
+ *(u32 *)(p+ 3) = i;
+ *(u8 *)(p+ 7) = 0x9a; /* lcall $__HYPERVISOR_CS,&hypercall */
+ *(u32 *)(p+ 8) = (u32)&hypercall;
+ *(u16 *)(p+12) = (u16)__HYPERVISOR_CS;
+ *(u8 *)(p+14) = 0xc3; /* ret */
+ }
+
+ /*
+ * HYPERVISOR_iret is special because it doesn't return and expects a
+ * special stack frame. Guests jump at this transfer point instead of
+ * calling it.
+ */
+ p = (char *)(hypercall_page + (__HYPERVISOR_iret * 32));
+ *(u8 *)(p+ 0) = 0x50; /* push %eax */
+ *(u8 *)(p+ 1) = 0x9c; /* pushf */
+ *(u8 *)(p+ 2) = 0xfa; /* cli */
+ *(u8 *)(p+ 3) = 0xb8; /* mov $<i>,%eax */
+ *(u32 *)(p+ 4) = __HYPERVISOR_iret;
+ *(u8 *)(p+ 8) = 0x9a; /* lcall $__HYPERVISOR_CS,&hypercall */
+ *(u32 *)(p+ 9) = (u32)&hypercall;
+ *(u16 *)(p+13) = (u16)__HYPERVISOR_CS;
+}
+
+static void hypercall_page_initialise_ring1_kernel(void *hypercall_page)
+{
+ char *p;
+ int i;
+
+ /* Fill in all the transfer points with template machine code. */
+
for ( i = 0; i < (PAGE_SIZE / 32); i++ )
{
p = (char *)(hypercall_page + (i * 32));
@@ -314,6 +359,14 @@
*(u8 *)(p+ 1) = 0xb8; /* mov $__HYPERVISOR_iret,%eax */
*(u32 *)(p+ 2) = __HYPERVISOR_iret;
*(u16 *)(p+ 6) = 0x82cd; /* int $0x82 */
+}
+
+void hypercall_page_initialise(void *hypercall_page)
+{
+ if ( supervisor_mode_kernel )
+ hypercall_page_initialise_ring0_kernel(hypercall_page);
+ else
+ hypercall_page_initialise_ring1_kernel(hypercall_page);
}
/*
diff -r 6060937db0fe -r ee8041b0ab86 xen/arch/x86/x86_64/mm.c
--- a/xen/arch/x86/x86_64/mm.c Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/x86_64/mm.c Mon Feb 27 14:52:43 2006
@@ -228,7 +228,7 @@
long do_stack_switch(unsigned long ss, unsigned long esp)
{
- fixup_guest_selector(ss);
+ fixup_guest_stack_selector(ss);
current->arch.guest_context.kernel_ss = ss;
current->arch.guest_context.kernel_sp = esp;
return 0;
@@ -315,7 +315,7 @@
/* Validate and fix up the target code selector. */
cs = a >> 16;
- fixup_guest_selector(cs);
+ fixup_guest_code_selector(cs);
if ( !guest_gate_selector_okay(cs) )
goto bad;
a = d->a = (d->a & 0xffffU) | (cs << 16);
diff -r 6060937db0fe -r ee8041b0ab86 xen/common/dom0_ops.c
--- a/xen/common/dom0_ops.c Mon Feb 27 11:02:00 2006
+++ b/xen/common/dom0_ops.c Mon Feb 27 14:52:43 2006
@@ -170,6 +170,13 @@
cpumask_t cpu_exclude_map;
static domid_t rover = 0;
+ /*
+ * Running the domain 0 kernel in ring 0 is not compatible
+ * with multiple guests.
+ */
+ if ( supervisor_mode_kernel )
+ return -EINVAL;
+
dom = op->u.createdomain.domain;
if ( (dom > 0) && (dom < DOMID_FIRST_RESERVED) )
{
diff -r 6060937db0fe -r ee8041b0ab86 xen/common/kernel.c
--- a/xen/common/kernel.c Mon Feb 27 11:02:00 2006
+++ b/xen/common/kernel.c Mon Feb 27 14:52:43 2006
@@ -195,6 +195,8 @@
(1U << XENFEAT_writable_page_tables) |
(1U << XENFEAT_auto_translated_physmap) |
(1U << XENFEAT_pae_pgdir_above_4gb);
+ if ( supervisor_mode_kernel )
+ fi.submap |= 1U << XENFEAT_supervisor_mode_kernel;
break;
default:
return -EINVAL;
diff -r 6060937db0fe -r ee8041b0ab86 xen/include/asm-ia64/config.h
--- a/xen/include/asm-ia64/config.h Mon Feb 27 11:02:00 2006
+++ b/xen/include/asm-ia64/config.h Mon Feb 27 14:52:43 2006
@@ -39,6 +39,8 @@
//#define CONFIG_NR_CPUS 16
//leave SMP for a later time
//#undef CONFIG_SMP
+
+#define supervisor_mode_kernel (0)
#define MAX_DMADOM_PFN (0x7FFFFFFFUL >> PAGE_SHIFT) /* 31 addressable bits */
diff -r 6060937db0fe -r ee8041b0ab86 xen/include/asm-x86/config.h
--- a/xen/include/asm-x86/config.h Mon Feb 27 11:02:00 2006
+++ b/xen/include/asm-x86/config.h Mon Feb 27 14:52:43 2006
@@ -36,6 +36,12 @@
#define OPT_CONSOLE_STR "com1,vga"
#define NR_CPUS 32
+
+#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL
+# define supervisor_mode_kernel (1)
+#else
+# define supervisor_mode_kernel (0)
+#endif
/* Linkage for x86 */
#define __ALIGN .align 16,0x90
diff -r 6060937db0fe -r ee8041b0ab86 xen/include/asm-x86/desc.h
--- a/xen/include/asm-x86/desc.h Mon Feb 27 11:02:00 2006
+++ b/xen/include/asm-x86/desc.h Mon Feb 27 14:52:43 2006
@@ -27,9 +27,22 @@
#endif
/* Fix up the RPL of a guest segment selector. */
-#define fixup_guest_selector(sel) \
+#define __fixup_guest_selector(sel) \
((sel) = (((sel) & 3) >= GUEST_KERNEL_RPL) ? (sel) : \
(((sel) & ~3) | GUEST_KERNEL_RPL))
+
+/* Stack selectors don't need fixing up if the kernel runs in ring 0. */
+#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL
+#define fixup_guest_stack_selector(ss) ((void)0)
+#else
+#define fixup_guest_stack_selector(ss) __fixup_guest_selector(ss)
+#endif
+
+/*
+ * Code selectors are always fixed up. It allows the Xen exit stub to detect
+ * return to guest context, even when the guest kernel runs in ring 0.
+ */
+#define fixup_guest_code_selector(cs) __fixup_guest_selector(cs)
/*
* We need this function because enforcing the correct guest kernel RPL is
diff -r 6060937db0fe -r ee8041b0ab86 xen/include/asm-x86/x86_32/asm_defns.h
--- a/xen/include/asm-x86/x86_32/asm_defns.h Mon Feb 27 11:02:00 2006
+++ b/xen/include/asm-x86/x86_32/asm_defns.h Mon Feb 27 14:52:43 2006
@@ -48,9 +48,24 @@
#ifdef PERF_COUNTERS
#define PERFC_INCR(_name,_idx) \
- lock incl perfcounters+_name(,_idx,4)
+ lock incl perfcounters+_name(,_idx,4)
#else
#define PERFC_INCR(_name,_idx)
+#endif
+
+#ifdef CONFIG_X86_SUPERVISOR_MODE_KERNEL
+#define FIXUP_RING0_GUEST_STACK \
+ testl $2,8(%esp); \
+ jnz 1f; /* rings 2 & 3 permitted */ \
+ testl $1,8(%esp); \
+ jz 2f; \
+ ud2; /* ring 1 should not be used */ \
+ 2:cmpl $(__HYPERVISOR_VIRT_START),%esp; \
+ jge 1f; \
+ call fixup_ring0_guest_stack; \
+ 1:
+#else
+#define FIXUP_RING0_GUEST_STACK
#endif
#define BUILD_SMP_INTERRUPT(x,v) XBUILD_SMP_INTERRUPT(x,v)
@@ -61,6 +76,7 @@
".globl " STR(x) "\n\t" \
STR(x) ":\n\t" \
"pushl $"#v"<<16\n\t" \
+ STR(FIXUP_RING0_GUEST_STACK) \
STR(SAVE_ALL(a)) \
"movl %esp,%eax\n\t" \
"pushl %eax\n\t" \
@@ -72,6 +88,7 @@
__asm__( \
"\n" __ALIGN_STR"\n" \
"common_interrupt:\n\t" \
+ STR(FIXUP_RING0_GUEST_STACK) \
STR(SAVE_ALL(a)) \
"movl %esp,%eax\n\t" \
"pushl %eax\n\t" \
diff -r 6060937db0fe -r ee8041b0ab86
xen/arch/x86/x86_32/supervisor_mode_kernel.S
--- /dev/null Mon Feb 27 11:02:00 2006
+++ b/xen/arch/x86/x86_32/supervisor_mode_kernel.S Mon Feb 27 14:52:43 2006
@@ -0,0 +1,145 @@
+/*
+ * Handle stack fixup for guest running in RING 0.
+ *
+ * Copyright (c) 2006 Ian Campbell
+ *
+ * When a guest kernel is allowed to run in RING 0 a hypercall,
+ * interrupt or exception interrupting the guest kernel will not cause
+ * a privilege level change and therefore the stack will not be swapped
+ * to the Xen stack.
+ *
+ * To fix this we look for RING 0 activation frames with a stack
+ * pointer below HYPERVISOR_VIRT_START (indicating a guest kernel
+ * frame) and fix this up by locating the Xen stack via the TSS
+ * and moving the activation frame to the Xen stack. In the process we
+ * convert the frame into an inter-privilege frame returning to RING 1
+ * so that we can catch and reverse the process on exit.
+ */
+
+#include <xen/config.h>
+#include <asm/asm_defns.h>
+#include <public/xen.h>
+
+ # Upon entry the stack should be the Xen stack and contain:
+ # %ss, %esp, EFLAGS, %cs|1, %eip, ERROR, SAVE_ALL, RETURN
+ # On exit the stack should be %ss:%esp (i.e. the guest stack)
+ # and contain:
+ # EFLAGS, %cs, %eip, ERROR, SAVE_ALL, RETURN
+ ALIGN
+ENTRY(restore_ring0_guest)
+ # Point %gs:%esi to guest stack.
+RRG0: movw UREGS_ss+4(%esp),%gs
+ movl UREGS_esp+4(%esp),%esi
+
+ # Copy EFLAGS...EBX, RETURN from Xen stack to guest stack.
+ movl $(UREGS_kernel_sizeof>>2)+1,%ecx
+
+1: subl $4,%esi
+ movl -4(%esp,%ecx,4),%eax
+RRG1: movl %eax,%gs:(%esi)
+ loop 1b
+
+RRG2: andl $~3,%gs:UREGS_cs+4(%esi)
+
+ movl %gs,%eax
+
+ # We need to do this because these registers are not present
+ # on the guest stack so they cannot be restored by the code in
+ # restore_all_guest.
+RRG3: mov UREGS_ds+4(%esp),%ds
+RRG4: mov UREGS_es+4(%esp),%es
+RRG5: mov UREGS_fs+4(%esp),%fs
+RRG6: mov UREGS_gs+4(%esp),%gs
+
+RRG7: movl %eax,%ss
+ movl %esi,%esp
+
+ ret
+.section __ex_table,"a"
+ .long RRG0,domain_crash_synchronous
+ .long RRG1,domain_crash_synchronous
+ .long RRG2,domain_crash_synchronous
+ .long RRG3,domain_crash_synchronous
+ .long RRG4,domain_crash_synchronous
+ .long RRG5,domain_crash_synchronous
+ .long RRG6,domain_crash_synchronous
+ .long RRG7,domain_crash_synchronous
+.previous
+
+ # Upon entry the stack should be a guest stack and contain:
+ # EFLAGS, %cs, %eip, ERROR, RETURN
+ # On exit the stack should be the Xen stack and contain:
+ # %ss, %esp, EFLAGS, %cs|1, %eip, ERROR, RETURN
+ ALIGN
+ENTRY(fixup_ring0_guest_stack)
+ pushl %eax
+ pushl %ecx
+ pushl %ds
+ pushl %gs
+ pushl %esi
+
+ movw $__HYPERVISOR_DS,%ax
+ movw %ax,%ds
+
+ # Point %gs:%esi to guest stack frame.
+ movw %ss,%ax
+ movw %ax,%gs
+ movl %esp,%esi
+ # Account for entries on the guest stack:
+ # * Pushed by normal exception/interrupt/hypercall mechanisms
+ # * EFLAGS, %cs, %eip, ERROR == 4 words.
+ # * Pushed by the fixup routine
+ # * [RETURN], %eax, %ecx, %ds, %gs and %esi == 6 words.
+ addl $((6+4)*4),%esi
+
+ # %gs:%esi now points to the guest stack before the
+ # interrupt/exception occured.
+
+ /*
+ * Reverse the __TSS macro, giving us the CPU number.
+ * The TSS for this cpu is at init_tss + ( cpu * 128 ).
+ */
+ str %ecx
+ shrl $3,%ecx # Calculate GDT index
for TSS.
+ subl $(FIRST_RESERVED_GDT_ENTRY+8),%ecx # %ecx = 2*cpu.
+ shll $6,%ecx # Each TSS entry is
0x80 bytes
+ addl $init_tss,%ecx # but we have 2*cpu
from above.
+
+ # Load Xen stack from TSS.
+ movw TSS_ss0(%ecx),%ax
+TRP1: movw %ax,%ss
+ movl TSS_esp0(%ecx),%esp
+
+ pushl %gs
+ pushl %esi
+
+ # Move EFLAGS, %cs, %eip, ERROR, RETURN, %eax, %ecx, %ds, %gs, %esi
+ # from guest stack to Xen stack.
+ movl $10,%ecx
+1: subl $4,%esp
+ subl $4,%esi
+TRP2: movl %gs:(%esi),%eax
+ movl %eax,(%esp)
+ loop 1b
+
+ # CS = CS|1 to simulate RING1 stack frame.
+ orl $1,32(%esp)
+
+ popl %esi
+ popl %gs
+ popl %ds
+ popl %ecx
+ popl %eax
+ ret
+.section __ex_table,"a"
+ .long TRP1,domain_crash_synchronous
+ .long TRP2,domain_crash_synchronous
+.previous
+
+domain_crash_synchronous_string:
+ .asciz "domain_crash_sync called from supervisor_mode_kernel.S (%lx)\n"
+
+domain_crash_synchronous:
+ pushl $domain_crash_synchronous_string
+ call printf
+ jmp __domain_crash_synchronous
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