linux-kernel - Re: [PATCH 2/3] x86: Pass in pt_regs pointer for syscalls that need it

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Message-ID: <4992812B.1050800@kernel.org>
Date:	Wed, 11 Feb 2009 16:41:31 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Brian Gerst <brgerst@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] x86: Pass in pt_regs pointer for syscalls that need
 it

Hello, Brian.

Brian Gerst wrote:
> Some syscalls need to access the pt_regs structure, either to copy
> user register state or to modifiy it.  This patch adds stubs to load
> the address of the pt_regs struct into the %eax register, and changes
> the syscalls to regparm(1) to receive the pt_regs pointer as the
> first argument.

Heh... neat.  Just one question.

> -asmlinkage long sys_iopl(unsigned long regsp)
> +ptregscall long sys_iopl(struct pt_regs *regs, unsigned int level)
>  {
> -	struct pt_regs *regs = (struct pt_regs *)&regsp;
> -	unsigned int level = regs->bx;

Here and at other places where the function takes more than one
arguments, wouldn't it be better to just take *regs and use other
parameters from regs?  That way we won't have to worry about gcc
corrupting register frame at all and I think it's cleaner that way.

Thanks.

-- 
tejun
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