From 68df3755e383e6fecf2354a67b08f92f18536594 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 19 Mar 2009 11:10:17 -0700 Subject: 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 Signed-off-by: Linus Torvalds --- Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 2e2f4a4324a..f607658ac89 100644 --- a/Makefile +++ b/Makefile @@ -347,6 +347,7 @@ KBUILD_CPPFLAGS := -D__KERNEL__ 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) -- cgit v1.2.3 From d0115552cdb0b4d4146975889fee2e9355515c4b Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 19 Mar 2009 15:53:19 -0700 Subject: Move cc-option to below arch-specific setup Sam Ravnborg says: "We have several architectures that plays strange games with $(CC) and $(CROSS_COMPILE). So we need to postpone any use of $(call cc-option..) until we have included the arch specific Makefile so we try with the correct $(CC) version." Requested-by: Sam Ravnborg Signed-off-by: Linus Torvalds --- Makefile | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index f607658ac89..a2c2efe9e82 100644 --- a/Makefile +++ b/Makefile @@ -347,7 +347,6 @@ KBUILD_CPPFLAGS := -D__KERNEL__ 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) @@ -567,6 +566,9 @@ KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) # disable pointer signed / unsigned warnings in gcc 4.0 KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,) +# disable invalid "can't wrap" optimzations for signed / pointers +KBUILD_CFLAGS += $(call cc-option,-fwrapv) + # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments # But warn user when we do so warn-assign = \ -- cgit v1.2.3