From a484e54fae891703cbe1c9ec1b536605f11f5482 Mon Sep 17 00:00:00 2001 From: David Daney Date: Fri, 9 Jul 2010 14:52:05 -0700 Subject: [PATCH] tracing: Fix $mcount_regex for MIPS in recordmcount.pl 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 recordmcount.pl, 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 code. 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 recordmcount.pl 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 $mcount_regex to only match on these. Acked-by: Ralf Baechle Acked-by: Wu Zhangjin Signed-off-by: David Daney LKML-Reference: <1278712325-12050-1-git-send-email-ddaney@caviumnetworks.com> Cc: Li Hong Cc: Ingo Molnar Cc: Matt Fleming Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index f3c9c0a90b9..0171060b5fd 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -326,7 +326,7 @@ if ($arch eq "x86_64") { # 14: R_MIPS_NONE *ABS* # 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\$"; }