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Diffstat (limited to 'arch/x86/kernel/kprobes.c')
-rw-r--r--arch/x86/kernel/kprobes.c33
1 files changed, 17 insertions, 16 deletions
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 675879b..1bfb6cf 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -126,16 +126,22 @@ static void __kprobes synthesize_reljump(void *from, void *to)
}
/*
- * Check for the REX prefix which can only exist on X86_64
- * X86_32 always returns 0
+ * Skip the prefixes of the instruction.
*/
-static int __kprobes is_REX_prefix(kprobe_opcode_t *insn)
+static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn)
{
+ insn_attr_t attr;
+
+ attr = inat_get_opcode_attribute((insn_byte_t)*insn);
+ while (inat_is_legacy_prefix(attr)) {
+ insn++;
+ attr = inat_get_opcode_attribute((insn_byte_t)*insn);
+ }
#ifdef CONFIG_X86_64
- if ((*insn & 0xf0) == 0x40)
- return 1;
+ if (inat_is_rex_prefix(attr))
+ insn++;
#endif
- return 0;
+ return insn;
}
/*
@@ -272,6 +278,9 @@ static int __kprobes can_probe(unsigned long paddr)
*/
static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
{
+ /* Skip prefixes */
+ insn = skip_prefixes(insn);
+
switch (*insn) {
case 0xfa: /* cli */
case 0xfb: /* sti */
@@ -280,13 +289,6 @@ static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
return 1;
}
- /*
- * 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 (is_REX_prefix(insn))
- return is_IF_modifier(++insn);
-
return 0;
}
@@ -803,9 +805,8 @@ static void __kprobes resume_execution(struct kprobe *p,
unsigned long orig_ip = (unsigned long)p->addr;
kprobe_opcode_t *insn = p->ainsn.insn;
- /*skip the REX prefix*/
- if (is_REX_prefix(insn))
- insn++;
+ /* Skip prefixes */
+ insn = skip_prefixes(insn);
regs->flags &= ~X86_EFLAGS_TF;
switch (*insn) {
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