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| author | Andy Lutomirski <luto@kernel.org> | 2015-07-21 19:27:18 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-07-22 09:20:29 +0300 |
| commit | b2c51106c7581866c37ffc77c5d739f3d4b7cbc9 (patch) | |
| tree | 228177956681a7e4b1afec070d12f2071dafc740 | |
| parent | f2a50f8b7da45ff2de93a71393e715a2ab9f3b68 (diff) | |
| download | linux-b2c51106c7581866c37ffc77c5d739f3d4b7cbc9.tar.xz | |
x86/build: Fix detection of GCC -mpreferred-stack-boundary support
As per:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
GCC only allows -mpreferred-stack-boundary=3 on x86_64 if -mno-sse is set.
That means that cc-option will not detect -mpreferred-stack-boundary=3
support, because we test for it before setting -mno-sse.
Fix it by reordering the Makefile bits.
Compile-tested only. This should help avoid code generation
issues such as the one that was worked around in:
b96fecbfa8c8 ("x86/fpu: Fix boot crash in the early FPU code")
I'm a bit concerned that we could still have problems on older
GCC versions given that our asm code does not respect GCC's idea
of the ABI-required stack alignment.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f5297c192969adfa0d28b84cf8a22d59573db26d.1436126872.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/Makefile | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 118e6debc483..054ff969fcdb 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -39,6 +39,16 @@ ifdef CONFIG_X86_NEED_RELOCS LDFLAGS_vmlinux := --emit-relocs endif +# +# Prevent GCC from generating any FP code by mistake. +# +# This must happen before we try the -mpreferred-stack-boundary, see: +# +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383 +# +KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow +KBUILD_CFLAGS += $(call cc-option,-mno-avx,) + ifeq ($(CONFIG_X86_32),y) BITS := 32 UTS_MACHINE := i386 @@ -167,9 +177,6 @@ KBUILD_CFLAGS += -pipe KBUILD_CFLAGS += -Wno-sign-compare # KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -# prevent gcc from generating any FP code by mistake -KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -KBUILD_CFLAGS += $(call cc-option,-mno-avx,) KBUILD_CFLAGS += $(mflags-y) KBUILD_AFLAGS += $(mflags-y) |