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x86: introduce REX prefix helper for kprobes

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Fold some small ifdefs into a helper function.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Harvey Harrison
2008-01-30 13:32:14 +01:00
committed by Ingo Molnar
parent e419190683
commit 9930927f36
1 changed files with 19 additions and 8 deletions
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27
arch/x86/kernel/kprobes.c
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@@ -170,6 +170,19 @@ static void __kprobes set_jmp_op(void *from, void *to)
jop->op = RELATIVEJUMP_INSTRUCTION; jop->op = RELATIVEJUMP_INSTRUCTION;
} }
/*
* Check for the REX prefix which can only exist on X86_64
* X86_32 always returns 0
*/
static int __kprobes is_REX_prefix(kprobe_opcode_t *insn)
{
#ifdef CONFIG_X86_64
if ((*insn & 0xf0) == 0x40)
return 1;
#endif
return 0;
}
/* /*
* Returns non-zero if opcode is boostable. * Returns non-zero if opcode is boostable.
* RIP relative instructions are adjusted at copying time in 64 bits mode * RIP relative instructions are adjusted at copying time in 64 bits mode
@@ -239,14 +252,14 @@ static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
case 0x9d: /* popf/popfd */ case 0x9d: /* popf/popfd */
return 1; return 1;
} }
#ifdef CONFIG_X86_64
/* /*
* on 64 bit x86, 0x40-0x4f are prefixes so we need to look * on X86_64, 0x40-0x4f are REX prefixes so we need to look
* at the next byte instead.. but of course not recurse infinitely * at the next byte instead.. but of course not recurse infinitely
*/ */
if (*insn >= 0x40 && *insn <= 0x4f) if (is_REX_prefix(insn))
return is_IF_modifier(++insn); return is_IF_modifier(++insn);
#endif
return 0; return 0;
} }
@@ -284,7 +297,7 @@ static void __kprobes fix_riprel(struct kprobe *p)
} }
/* Skip REX instruction prefix. */ /* Skip REX instruction prefix. */
if ((*insn & 0xf0) == 0x40) if (is_REX_prefix(insn))
++insn; ++insn;
if (*insn == 0x0f) { if (*insn == 0x0f) {
@@ -748,11 +761,9 @@ static void __kprobes resume_execution(struct kprobe *p,
unsigned long orig_ip = (unsigned long)p->addr; unsigned long orig_ip = (unsigned long)p->addr;
kprobe_opcode_t *insn = p->ainsn.insn; kprobe_opcode_t *insn = p->ainsn.insn;
#ifdef CONFIG_X86_64
/*skip the REX prefix*/ /*skip the REX prefix*/
if (*insn >= 0x40 && *insn <= 0x4f) if (is_REX_prefix(insn))
insn++; insn++;
#endif
regs->flags &= ~X86_EFLAGS_TF; regs->flags &= ~X86_EFLAGS_TF;
switch (*insn) { switch (*insn) {