src/patches/suse-2.6.27.25/patches.fixes/add-fwrapv-to-gcc-CFLAGS

   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