On Fri, Jul 17, 2015 at 12:44:42PM -0700, Andy Lutomirski wrote:
> On Fri, Jul 17, 2015 at 12:43 PM, Ingo Molnar <mi...@kernel.org> wrote:
> >
> > * Josh Poimboeuf <jpoim...@redhat.com> wrote:
> >
> >>  ENTRY(aesni_set_key)
> >> +     FRAME
> >>  #ifndef __x86_64__
> >>       pushl KEYP
> >>       movl 8(%esp), KEYP              # ctx
> >> @@ -1905,6 +1907,7 @@ ENTRY(aesni_set_key)
> >>  #ifndef __x86_64__
> >>       popl KEYP
> >>  #endif
> >> +     ENDFRAME
> >>       ret
> >>  ENDPROC(aesni_set_key)
> >
> > So cannot we make this a bit more compact and less fragile?
> >
> > Instead of:
> >
> >         ENTRY(aesni_set_key)
> >                 FRAME
> >         ...
> >                 ENDFRAME
> >                 ret
> >         ENDPROC(aesni_set_key)
> >
> >
> > How about writing this as:
> >
> >         FUNCTION_ENTRY(aesni_set_key)
> >         ...
> >         FUNCTION_RETURN(aesni_set_key)
> >
> > which does the same thing in a short, symmetric construct?
> >
> > One potential problem with this approach would be that what 'looks' like an 
> > entry
> > declaration, but it will now generate real code.
> >
> > OTOH if people find this intuitive enough then it's a lot harder to mess it 
> > up,
> > and I think 'RETURN' makes it clear enough that there's a real instruction
> > generated there.
> >
> 
> How about FUNCTION_PROLOGUE and FUNCTION_EPILOGUE?

Perhaps the macro name should describe what the epilogue does, since
frame pointers aren't required for _all_ functions, only those which
don't have call instructions.

What do you think about ENTRY_FRAME and ENDPROC_FRAME_RETURN?  The
ending macro is kind of long, but at least it a) matches the existing
ENTRY/ENDPROC convention for asm functions; b) gives a clue that frame
pointers are involved; and c) lets you know that the return is there.

-- 
Josh
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