linux-kernel - Re: [PATCH] i386/audit: stop scribbling on the stack frame

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Message-ID: <544AB462.9070708@zytor.com>
Date:	Fri, 24 Oct 2014 13:19:46 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Eric Paris <eparis@...hat.com>,
	Andy Lutomirski <luto@...capital.net>
CC:	Richard Guy Briggs <rgb@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-audit@...hat.com
Subject: Re: [PATCH] i386/audit: stop scribbling on the stack frame

On 10/23/2014 12:38 PM, Eric Paris wrote:
>>
>> After the call __audit_syscall_entry aren't they already polluted?
>> Isn't that the reason we need to reload EAX?
> 
> Well, I guess EAX is special...
> 

Because system calls are "asmlinkage", all the parameters are on the
stack, but %eax is used as the index into the system call table.  This
should thus be fine until we get rid of regparm(0) entirely, if that
ever happens.

	-hpa


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