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Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent

From Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups linux.kernel
Subject Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent
Date 2017-09-14 19:40 +0200
Message-ID <upGhk-81E-9@gated-at.bofh.it> (permalink)
References (4 earlier) <ukBBE-ap-27@gated-at.bofh.it> <ule0h-1NH-1@gated-at.bofh.it> <upDCO-6hR-9@gated-at.bofh.it> <upFXY-7Vl-13@gated-at.bofh.it> <upG7E-7Yy-9@gated-at.bofh.it>
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On Thu, Sep 14, 2017 at 12:26:27PM -0500, Josh Poimboeuf wrote:
> On Thu, Sep 14, 2017 at 10:16:08AM -0700, Linus Torvalds wrote:
> > On Thu, Sep 14, 2017 at 7:48 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > >
> > > As it turns out, the real problem with this option is that it imposes a
> > > penalty for CONFIG_FRAME_POINTER=n: even with frame pointers disabled,
> > > it forces the frame pointer to be saved for each function which uses the
> > > inline asm "call" statements.  Our current solution doesn't do that.
> > 
> > But couldn't we make the whole stack pointer clobber be dependent on
> > CONFIG_FRAME_POINTER?
> > 
> > The only reason we do it is to make sure the frame pointer is set up
> > before the inline asm is emitted, but with frame pointers disabled we
> > don't need to.
> 
> We could, but then that would mean either:
> 
>  a) uglifying the 15 or so relevant inline asm locations with ifdefs; or

Actually I guess we could put the "sp" in a macro...  I'll try it.

-- 
Josh

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Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Josh Poimboeuf <jpoimboe@redhat.com> - 2017-09-14 16:50 +0200
  Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Linus Torvalds <torvalds@linux-foundation.org> - 2017-09-14 19:20 +0200
    Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Josh Poimboeuf <jpoimboe@redhat.com> - 2017-09-14 19:30 +0200
      Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Josh Poimboeuf <jpoimboe@redhat.com> - 2017-09-14 19:40 +0200
        Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Linus Torvalds <torvalds@linux-foundation.org> - 2017-09-14 20:30 +0200
          Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Josh Poimboeuf <jpoimboe@redhat.com> - 2017-09-14 20:50 +0200
            Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more  clear and consistent Josh Poimboeuf <jpoimboe@redhat.com> - 2017-09-15 18:20 +0200

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