path: root/lib
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authorPeter Oberparleiter <oberpar@linux.vnet.ibm.com>2014-02-06 15:58:20 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-20 11:06:11 -0800
commitf878b94f967e1c6ee0d3c220063db3ff52fe0448 (patch)
treeb4b7b3d919f2f58e4ba3c8033708c9ed79d0372e /lib
parentf19148c7959cd94e70a32a92d05a19e92d9826e8 (diff)
x86, hweight: Fix BUG when booting with CONFIG_GCOV_PROFILE_ALL=y
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@linux.ee> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/52F3A30C.7050205@linux.vnet.ibm.com Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib')
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile
index c55a037a354e..9efe480b975e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -45,6 +45,7 @@ lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
lib-$(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