From 9930927f36ac3e39ffa674dc23ef06f13c39cef7 Mon Sep 17 00:00:00 2001 From: Harvey Harrison Date: Wed, 30 Jan 2008 13:32:14 +0100 Subject: [PATCH] x86: introduce REX prefix helper for kprobes Fold some small ifdefs into a helper function. Signed-off-by: Harvey Harrison Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/kprobes.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 4e33329ce8..b1804e4023 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -170,6 +170,19 @@ static void __kprobes set_jmp_op(void *from, void *to) 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. * 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 */ 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 */ - if (*insn >= 0x40 && *insn <= 0x4f) + if (is_REX_prefix(insn)) return is_IF_modifier(++insn); -#endif + return 0; } @@ -284,7 +297,7 @@ static void __kprobes fix_riprel(struct kprobe *p) } /* Skip REX instruction prefix. */ - if ((*insn & 0xf0) == 0x40) + if (is_REX_prefix(insn)) ++insn; if (*insn == 0x0f) { @@ -748,11 +761,9 @@ static void __kprobes resume_execution(struct kprobe *p, unsigned long orig_ip = (unsigned long)p->addr; kprobe_opcode_t *insn = p->ainsn.insn; -#ifdef CONFIG_X86_64 /*skip the REX prefix*/ - if (*insn >= 0x40 && *insn <= 0x4f) + if (is_REX_prefix(insn)) insn++; -#endif regs->flags &= ~X86_EFLAGS_TF; switch (*insn) { -- 2.39.5