linux-kernel - Re: [PATCH 1/many] PROC macro to annotate functions in assembly files

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Date:	Thu, 18 Dec 2008 13:40:55 +0100
From:	"Alexander van Heukelum" <heukelum@...tmail.fm>
To:	"Cyrill Gorcunov" <gorcunov@...il.com>
Cc:	"Sam Ravnborg" <sam@...nborg.org>,
	"Jan Beulich" <jbeulich@...ell.com>, linux-arch@...r.kernel.org,
	"Alexander van Heukelum" <heukelum@...lshack.com>,
	"Ingo Molnar" <mingo@...e.hu>,
	"LKML" <linux-kernel@...r.kernel.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/many] PROC macro to annotate functions in assembly files


On Thu, 18 Dec 2008 15:03:25 +0300, "Cyrill Gorcunov"
<gorcunov@...il.com> said:
> On Thu, Dec 18, 2008 at 12:51 PM, Alexander van Heukelum
> <heukelum@...tmail.fm> wrote:
> [...]
> >> >
> >> > Sam, I think eventually we should get something like this:
> >> >
> >> > - KPROBE will be eliminated and explicit section descriptions
> >> >   are to be used
> >> > - ENTRY could be used / or renamed for something more descriptive
> >> >   and being used aligned jmp targets or in case of procs with
> >> >   shared body
> >
> > I don't think ENTRY should be used for nested procedures. If the
> > author wants to do something like that, he better knew something
> > about the assembler anyhow.
> 
> Author anyway have to knew something. We can't bring some kind
> of lexical machine that eliminate this needing :)
> 
> >
> >> > - PROC/ENDPROC are to replace old ENTRY/END for procs being called
> >> >   mostly from C code
> >
> > Currently there is many different patterns. Some functions use ENTRY
> > without END, some use ENTRY/ENDPROC, some use ENDPROC without annotation
> > at the start...
> 
> Alexander, I was just trying to say Sam about what we're planning to get
> at the end of all this procedure. I mean I know there are some issues to
> be fixed first.

I understood, but I wanted to avoid the meme that this procedure is
just ebout renaming ENTRY->PROC and END->ENDPROC ;).

> Fix me if I'm wrong.
> 
> >
> >> So what prevents us from extending ENTRY/END instead of introducing
> >> another set?
> >
> > ENTRY/END alone is not enough if one wants to be able to distinguish
> > between code (functions) and non-executed data.
> >
> >> Let us try to extend what we have and not introduce something new.
> >
> > Agreed. I vote to complement the existing ENDPROC annotation with
> > the proposed PROC annotation. Let's call that an extension, not
> > something new ;). As it stands it is not impossible to go with
> > ENTRY/ENDPROC for code and ENTRY/END for data. However, ENTRY
> > implies alignment and the prefered alignment for code and data
> > might differ.
> 
> If ENTRY will be used for data objects it shouldn't contain any kind of
> alignment since in general we could have arrays of bytes, words and so
> on.

I would suggest using sizeof(long) alignment for data.

Greetings,
   Alexander
-- 
  Alexander van Heukelum
  heukelum@...tmail.fm

-- 
http://www.fastmail.fm - mmm... Fastmail...

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