Commit 68df3755e383e6fecf2354a67b08f92f18536594
1 parent
a1e4ee2286
Add '-fwrapv' to gcc CFLAGS
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>
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Makefile
... | ... | @@ -347,6 +347,7 @@ |
347 | 347 | KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ |
348 | 348 | -fno-strict-aliasing -fno-common \ |
349 | 349 | -Werror-implicit-function-declaration |
350 | +KBUILD_CFLAGS += $(call cc-option,-fwrapv) | |
350 | 351 | KBUILD_AFLAGS := -D__ASSEMBLY__ |
351 | 352 | |
352 | 353 | # Read KERNELRELEASE from include/config/kernel.release (if it exists) |