This is a note to let you know that I've just added the patch titled
x86, hweight: Fix BUG when booting with CONFIG_GCOV_PROFILE_ALL=y
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-hweight-fix-bug-when-booting-with-config_gcov_profile_all-y.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6583327c4dd55acbbf2a6f25e775b28b3abf9a42 Mon Sep 17 00:00:00 2001
From: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
Date: Thu, 6 Feb 2014 15:58:20 +0100
Subject: x86, hweight: Fix BUG when booting with CONFIG_GCOV_PROFILE_ALL=y
From: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
commit 6583327c4dd55acbbf2a6f25e775b28b3abf9a42 upstream.
Commit d61931d89b, "x86: Add optimized popcnt variants" introduced
compile flag -fcall-saved-rdi for lib/hweight.c. When combined with
options -fprofile-arcs and -O2, this flag causes gcc to generate
broken constructor code. As a result, a 64 bit x86 kernel compiled
with CONFIG_GCOV_PROFILE_ALL=y prints message "gcov: could not create
file" and runs into sproadic BUGs during boot.
The gcc people indicate that these kinds of problems are endemic when
using ad hoc calling conventions. It is therefore best to treat any
file compiled with ad hoc calling conventions as an isolated
environment and avoid things like profiling or coverage analysis,
since those subsystems assume a "normal" calling conventions.
This patch avoids the bug by excluding lib/hweight.o from coverage
profiling.
Reported-by: Meelis Roos <mroos@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/52F3A30C.7050205@xxxxxxxxxxxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/Makefile | 1 +
1 file changed, 1 insertion(+)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -47,6 +47,7 @@ lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) +=
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
lib-$(CONFIG_PERCPU_RWSEM) += percpu-rwsem.o
+GCOV_PROFILE_hweight.o := n
CFLAGS_hweight.o = $(subst $(quote),,$(CONFIG_ARCH_HWEIGHT_CFLAGS))
obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
Patches currently in stable-queue which might be from oberpar@xxxxxxxxxxxxxxxxxx are
queue-3.12/x86-hweight-fix-bug-when-booting-with-config_gcov_profile_all-y.patch
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