lkml.org 
[lkml]   [2007]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
Subjectproblem with x86-prepare-kprobes-code-for-unification.patch
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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-11-10 01:31    [W:0.033 / U:1.992 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site