From f878b94f967e1c6ee0d3c220063db3ff52fe0448 Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Thu, 6 Feb 2014 15:58:20 +0100 Subject: 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 Cc: Andrew Morton Signed-off-by: Peter Oberparleiter Link: http://lkml.kernel.org/r/52F3A30C.7050205@linux.vnet.ibm.com Signed-off-by: H. Peter Anvin Signed-off-by: Greg Kroah-Hartman --- lib/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'lib') 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_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 -- cgit v1.2.3