From: Linus Torvalds Date: Thu, 19 Mar 2009 18:10:17 +0000 (-0700) Subject: Add '-fwrapv' to gcc CFLAGS X-Git-Tag: v2.6.28.9~25 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92db6956ecd01ceb7934be0252b3b184a82ebb64;p=thirdparty%2Fkernel%2Fstable.git Add '-fwrapv' to gcc CFLAGS commit 68df3755e383e6fecf2354a67b08f92f18536594 upstream. This makes sure that gcc doesn't try to optimize away wrapping arithmetic, which the kernel occasionally uses for overflow testing, ie things like if (ptr + offset < ptr) which technically is undefined for non-unsigned types. See http://bugzilla.kernel.org/show_bug.cgi?id=12597 for details. Not all versions of gcc support it, so we need to make it conditional (it looks like it was introduced in gcc-3.4). Reminded-by: Alan Cox Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/Makefile b/Makefile index 2b46f70958563..987d21b3e4daa 100644 --- a/Makefile +++ b/Makefile @@ -341,6 +341,7 @@ KBUILD_CPPFLAGS := -D__KERNEL__ $(LINUXINCLUDE) KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common \ -Werror-implicit-function-declaration +KBUILD_CFLAGS += $(call cc-option,-fwrapv) KBUILD_AFLAGS := -D__ASSEMBLY__ # Read KERNELRELEASE from include/config/kernel.release (if it exists)