projects / people / pmueller / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 00e5a55c BS |
1 | From: Linus Torvalds <torvalds@linux-foundation.org> |
| 2 | Date: Thu, 19 Mar 2009 18:10:17 +0000 (-0700) | |
| 3 | Subject: Add '-fwrapv' to gcc CFLAGS | |
| 4 | Patch-mainline: 2.6.29 | |
| 5 | Git-commit: 68df3755e383e6fecf2354a67b08f92f18536594 | |
| 6 | References: bko#12597 bnc#487106 | |
| 7 | ||
| 8 | Add '-fwrapv' to gcc CFLAGS | |
| 9 | ||
| 10 | This makes sure that gcc doesn't try to optimize away wrapping | |
| 11 | arithmetic, which the kernel occasionally uses for overflow testing, ie | |
| 12 | things like | |
| 13 | ||
| 14 | if (ptr + offset < ptr) | |
| 15 | ||
| 16 | which technically is undefined for non-unsigned types. See | |
| 17 | ||
| 18 | http://bugzilla.kernel.org/show_bug.cgi?id=12597 | |
| 19 | ||
| 20 | for details. | |
| 21 | ||
| 22 | Not all versions of gcc support it, so we need to make it conditional | |
| 23 | (it looks like it was introduced in gcc-3.4). | |
| 24 | ||
| 25 | Reminded-by: Alan Cox <alan@lxorguk.ukuu.org.uk> | |
| 26 | Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> | |
| 27 | Acked-by: Jeff Mahoney <jeffm@suse.com> | |
| 28 | --- | |
| 29 | ||
| 30 | Makefile | 1 + | |
| 31 | 1 file changed, 1 insertion(+) | |
| 32 | ||
| 33 | --- a/Makefile | |
| 34 | +++ b/Makefile | |
| 35 | @@ -341,6 +341,7 @@ KBUILD_CPPFLAGS := -D__KERNEL__ $(LINUXI | |
| 36 | KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ | |
| 37 | -fno-strict-aliasing -fno-common \ | |
| 38 | -Werror-implicit-function-declaration | |
| 39 | +KBUILD_CFLAGS += $(call cc-option,-fwrapv) | |
| 40 | KBUILD_AFLAGS := -D__ASSEMBLY__ | |
| 41 | ||
| 42 | # Warn about unsupported modules in kernels built inside Autobuild |