From: Arnd Bergmann Date: Mon, 25 Apr 2016 15:35:30 +0000 (+0200) Subject: gcov: disable tree-loop-im to reduce stack usage X-Git-Tag: v3.2.82~77 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=defacd216d652459350394f5d9b4c18ca3143cd8;ds=sidebyside gcov: disable tree-loop-im to reduce stack usage commit c87bf431448b404a6ef5fbabd74c0e3e42157a7f upstream. Enabling CONFIG_GCOV_PROFILE_ALL produces us a lot of warnings like lib/lz4/lz4hc_compress.c: In function 'lz4_compresshcctx': lib/lz4/lz4hc_compress.c:514:1: warning: the frame size of 1504 bytes is larger than 1024 bytes [-Wframe-larger-than=] After some investigation, I found that this behavior started with gcc-4.9, and opened https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69702. A suggested workaround for it is to use the -fno-tree-loop-im flag that turns off one of the optimization stages in gcc, so the code runs a little slower but does not use excessive amounts of stack. We could make this conditional on the gcc version, but I could not find an easy way to do this in Kbuild and the benefit would be fairly small, given that most of the gcc version in production are affected now. I'm marking this for 'stable' backports because it addresses a bug with code generation in gcc that exists in all kernel versions with the affected gcc releases. Signed-off-by: Arnd Bergmann Acked-by: Peter Oberparleiter Signed-off-by: Michal Marek [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- diff --git a/Makefile b/Makefile index 98c276c53906..0e8d3a162ab1 100644 --- a/Makefile +++ b/Makefile @@ -352,7 +352,7 @@ AFLAGS_MODULE = LDFLAGS_MODULE = CFLAGS_KERNEL = AFLAGS_KERNEL = -CFLAGS_GCOV = -fprofile-arcs -ftest-coverage +CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im # Use LINUXINCLUDE when you must reference the include/ directory.