Re: [PATCH 2/6] x86: bug: prevent gcc distortions

[Linus Torvalds]

On Fri, May 18, 2018 at 11:34 AM <hpa@xxxxxxxxx> wrote:

> On May 18, 2018 11:25:32 AM PDT, Linus Torvalds <
torvalds@xxxxxxxxxxxxxxxxxxxx> 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