On Fri, Jul 17, 2015 at 1:37 PM, Josh Poimboeuf <jpoim...@redhat.com> wrote:
> 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.
>

This really is about frame pointers, right?  How about
ENTRY_FRAMEPTR_xyz where xyz can be prologue, epilogue, return,
whatever?

> --
> Josh



-- 
Andy Lutomirski
AMA Capital Management, LLC
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