Messages in this thread | | | Date | Thu, 14 Sep 2017 12:33:48 -0500 | From | Josh Poimboeuf <> | Subject | Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent |
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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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