Hi,
This code in kprobes_64.c from
x86-prepare-kprobes-code-for-unification.patch is problematic:
+static __always_inline int is_IF_modifier(kprobe_opcode_t *insn)
+{
+ switch (*insn) {
+ case 0xfa: /* cli */
+ case 0xfb: /* sti */
+ case 0xcf: /* iret/iretd */
+ case 0x9d: /* popf/popfd */
+ return 1;
+ }
+
+ /*
+ * on 64 bit x86, 0x40-0x4f are prefixes so we need to look
+ * at the next byte instead.. but of course not recurse infinitely
+ */
+ if (*insn >= 0x40 && *insn <= 0x4f && *insn > 0x4f)
+ return is_IF_modifier(++insn);
+ return 0;
+}
Firstly, the conditional in the if() doesn't seem to make much sense.
It appears to be miscopied from:
- if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf)
- return 1;
Secondly, the recursive inlining is making 4.0.2 complain:
/home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/kprobes_64.c: In function
'set_current_kprobe':
/home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/kprobes_64.c:152: sorry,
unimplemented: inlining failed in call to 'is_IF_modifier': recursive inlining
/home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/kprobes_64.c:166: sorry,
unimplemented: called from here
J
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