[patch] kprobes: dont steal interrupts from vm86

From: Stas Sergeev
Date: Tue Nov 09 2004 - 14:02:57 EST


Hello.

With kprobes enabled, vm86 doesn't feel
good. The problem is that kprobes steal
the interrupts (mainly int3 I think) from
it for no good reason.
The attached patch fixes the problem by
checking the VM flag where it makes sense.

Andrew, can this please be applied?

Signed-off-by: Stas Sergeev <stsp@xxxxxxxx>

--- linux-2.6.10-rc1/arch/i386/kernel/traps.c 2004-11-09 12:59:20.000000000 +0300
+++ linux-2.6.10-rc1-kprb/linux/arch/i386/kernel/traps.c 2004-11-09 13:35:18.625427704 +0300
@@ -408,7 +408,8 @@
#define DO_ERROR(trapnr, signr, str, name) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
- if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ if (!(regs->eflags & VM_MASK) && \
+ notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
@@ -422,7 +423,8 @@
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
- if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ if (!(regs->eflags & VM_MASK) && \
+ notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 0, regs, error_code, &info); \
@@ -431,7 +433,8 @@
#define DO_VM86_ERROR(trapnr, signr, str, name) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
- if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ if (!(regs->eflags & VM_MASK) && \
+ notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 1, regs, error_code, NULL); \
@@ -445,7 +448,8 @@
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
- if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ if (!(regs->eflags & VM_MASK) && \
+ notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
do_trap(trapnr, signr, str, 1, regs, error_code, &info); \
@@ -652,7 +656,8 @@
#ifdef CONFIG_KPROBES
asmlinkage int do_int3(struct pt_regs *regs, long error_code)
{
- if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
+ if (!(regs->eflags & VM_MASK) &&
+ notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
== NOTIFY_STOP)
return 1;
/* This is an interrupt gate, because kprobes wants interrupts
@@ -693,7 +698,8 @@

__asm__ __volatile__("movl %%db6,%0" : "=r" (condition));

- if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
+ if (!(regs->eflags & VM_MASK) &&
+ notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
SIGTRAP) == NOTIFY_STOP)
return;
/* It's safe to allow irq's after DR6 has been saved */