linux-kernel - Re: [PATCH] sh: remove RELOC_HIDE on exception handlers and syscall routines

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Date:	Tue, 10 Aug 2010 12:09:43 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Stuart Menefy <stuart.menefy@...com>
Cc:	Paul Mundt <lethal@...ux-sh.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sh: remove RELOC_HIDE on exception handlers and
 syscall routines

2010-08-09 (월), 16:29 +0100, Stuart Menefy:
> Unfortunately these are necessary, although it is nothing to do with linker
> relocation. These functions take a struct pt_regs as a parameter (not a
> pointer), and modify some of the fields of that structure. We needed a way
> to ensure that gcc didn't optimise away those assignments - to gcc
> they appear to be assignments to a local variable, so quite legitimately
> get optimised away. So we used RELOC_HIDE() as a way of doing that.
> 

Oh, I didn't know that. Thank you for the comments.


> A clearer way to do this would be to pass in a struct pt_regs pointer,
> but that would require going via a stub function which loads up the
> pointer.
> 
> Stuart
> 

So is it worth if I'm gonna work on it?


-- 
Regards,
Namhyung Kim


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