| From 68df3755e383e6fecf2354a67b08f92f18536594 Mon Sep 17 00:00:00 2001 |
| From: Linus Torvalds <torvalds@linux-foundation.org> |
| Date: Thu, 19 Mar 2009 11:10:17 -0700 |
| Subject: Add '-fwrapv' to gcc CFLAGS |
| |
| From: Linus Torvalds <torvalds@linux-foundation.org> |
| |
| 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 <alan@lxorguk.ukuu.org.uk> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| Makefile | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/Makefile |
| +++ b/Makefile |
| @@ -341,6 +341,7 @@ KBUILD_CPPFLAGS := -D__KERNEL__ $(LINUXI |
| 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) |
