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authorPeter Oberparleiter <oberpar@linux.vnet.ibm.com>2014-02-06 15:58:20 +0100
committerBen Hutchings <ben@decadent.org.uk>2014-04-02 00:58:49 +0100
commitd2fc4a69dadefef65e38ebfb15b8e29d9a3a9206 (patch)
tree99fe5dd9c3cc6c8445e274e2a26481e0a3201136 /lib
parent2fc5a0290af97e1891fedd02961240e92f1619e2 (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: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'lib')
-rw-r--r--lib/Makefile1
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile
index a4da283f5dc0..c06efca00c05 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
+GCOV_PROFILE_hweight.o := n
CFLAGS_hweight.o = $(subst $(quote),,$(CONFIG_ARCH_HWEIGHT_CFLAGS))
obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o