Messages in this thread | | | From | Nadav Amit <> | Subject | Re: [PATCH 2/6] x86: bug: prevent gcc distortions | Date | Fri, 18 May 2018 19:02:50 +0000 |
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hpa@zytor.com wrote:
> On May 18, 2018 11:50:12 AM PDT, Linus Torvalds <torvalds@linux-foundation.org> wrote: >> On Fri, May 18, 2018 at 11:34 AM <hpa@zytor.com> wrote: >> >>> On May 18, 2018 11:25:32 AM PDT, Linus Torvalds < >> torvalds@linux-foundation.org> wrote: >> >>> Unfortunately gcc doesn't guarantee that global assembly inlines will >> appear at the top of the file. >> >> Yeah. It really would be better to do the "asm version of -inline". >> >> We already do something like that for real *.S files on some >> architectures >> (because their assembly really wants it, eg >> >> arch/arm/Makefile: >> KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) >> -include >> asm/unified.h -msoft-float >> >> but I do want to point out that KBUILD_AFLAGS is *not* used for >> compiler-generated assembly, only for actual *.S files. >> >> Sadly, I don't actually know any way to make gcc call the 'as' phase >> with >> particular options. We can use "-Wa,xyzzy" to pass in xyzzy to the >> assembler, but there is no "-include" option for GNU as afaik. >> >> Can you perhaps define a macro symbol for "--defsym"? Probably not. >> >> Linus > > I looked at this thing a long time ago; it's not there, and the best would probably be to get global asm() working properly in gcc.
I can add a -Wa,[filename.s] switch. It works, but sort of undocumented.
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