linux-kernel - Re: [RFC 0/6] x86 tip asm ENTRY,ENDPROC cleanup

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Date:	Sat, 14 Feb 2009 12:42:55 +0100
From:	"Alexander van Heukelum" <heukelum@...tmail.fm>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Cyrill Gorcunov" <gorcunov@...il.com>,
	"Ingo Molnar" <mingo@...e.hu>, "Jan Beulich" <jbeulich@...ell.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC 0/6] x86 tip asm ENTRY,ENDPROC cleanup

On Fri, 13 Feb 2009 16:34:00 -0800, "H. Peter Anvin" <hpa@...or.com>
said:
> Alexander van Heukelum wrote:
> > 
> > Hi Cyrill,
> > 
> > I like this direction. If I understand correctly:
> > 
> > ENTRY/END or GLOBAL/END for data.
> > ENTRY/ENDPROC or GLOBAL/ENDPROC for functions.
> > 
> 
> Fine for functions, but it's really not okay to use the same macros for 
> data.  Furthermore, we need to consider special entry points that don't 
> behave like normal functions -- like system call or interrupt entry.
> 
> Why?  Because if we're compiling with frame pointers, we would like the 
> wrapper macros for functions to handle setting up and tearing down the 
> frame pointer, at least in the common case.

Hi Peter,

I see. But that would be new behaviour. I would propose to use
completely separate macro's to handle frame-setup code generation,
and keep ENTRY/GLOBAL/END/ENDPROC only for setting metadata and
alignment. I think it's worth it to spell out code-generating
macro's explicitly: there are not that many asm functions, and
quite a few of them would need special handling. I think noone
wants to see an ENDPROC_NOFRAMETEARDOWN ;).

The common-case example would look like this.

GLOBAL(c_callable_function)
        ENTER
        [asm-code]
        LEAVE
        ret
ENDPROC(c_callable_function)

Greetings,
    Alexander

> 	-hpa
-- 
  Alexander van Heukelum
  heukelum@...tmail.fm

-- 
http://www.fastmail.fm - I mean, what is it about a decent email service?

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