From: tip-bot for David Daney on
Commit-ID: a484e54fae891703cbe1c9ec1b536605f11f5482
Author: David Daney <ddaney(a)>
AuthorDate: Fri, 9 Jul 2010 14:52:05 -0700
Committer: Steven Rostedt <rostedt(a)>
CommitDate: Thu, 22 Jul 2010 14:55:43 -0400

tracing: Fix $mcount_regex for MIPS in

I found this issue in a locally patched 2.6.32.x, current kernels have
moved the offending code to an __init function which is skipped by, so the bug is not currently being exercised.
However, I think the patch is still a good idea, to avoid future
problems if _mcount were to ever have its address taken in normal

This is what I originally saw:

Although arch/mips/kernel/ftrace.c is built without -pg, and thus
contains no calls to _mcount, it does use the address of _mcount
in ftrace_make_nop(). This was causing relocations to be emitted
for _mcount which erronously took to be _mcount
call sites. The result was that the text of ftrace_make_nop()
would be patched with garbage leading to a system crash.

In non-module code, all _mcount call sites will have R_MIPS_26
relocations, so we restrict $mcount_regex to only match on these.

Acked-by: Ralf Baechle <ralf(a)>
Acked-by: Wu Zhangjin <wuzhangjin(a)>
Signed-off-by: David Daney <ddaney(a)>
LKML-Reference: <1278712325-12050-1-git-send-email-ddaney(a)>
Cc: Li Hong <lihong.hi(a)>
Cc: Ingo Molnar <mingo(a)>
Cc: Matt Fleming <matt(a)>
Signed-off-by: Steven Rostedt <rostedt(a)>
scripts/ | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/scripts/ b/scripts/
index f3c9c0a..0171060 100755
--- a/scripts/
+++ b/scripts/
@@ -326,7 +326,7 @@ if ($arch eq "x86_64") {
# 18: 00020021 nop
if ($is_module eq "0") {
- $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_26\\s+_mcount\$";
} else {
$mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_HI16\\s+_mcount\$";
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