linux-kernel - Re: [PATCH 2/5] x86/uprobes: implement x86 specific arch_uprobe_*

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 08 Aug 2012 17:02:33 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	linux-kernel@...r.kernel.org, x86@...nel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Roland McGrath <roland@...hat.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ananth N Mavinakaynahalli <ananth@...ibm.com>,
	stan_shebs@...tor.com
Subject: Re: [PATCH 2/5] x86/uprobes: implement x86 specific arch_uprobe_*_step

On 08/08/2012 04:53 PM, Oleg Nesterov wrote:
>> Why? I tried 'lock popf' and I got invalid instruction. The same for
>> 'rep popf'.
>
> 	int main(void)
> 	{
> 		asm volatile ("pushf; rep; popf");
>
> 		return 0;
> 	}
>

Just tested and it works. Hmm.

> OK, probably nobody should do this (although the kernel should not
> assume this imho), but
>
> 	asm volatile ("pushfw; popfw");
>
> doesn't look bad and the code is
>
> 	000000000040047c<main>:
> 	  40047c:       55                      push   %rbp
> 	  40047d:       48 89 e5                mov    %rsp,%rbp
> 	  400480:       66 9c                   pushfw
> 	  400482:       66 9d                   popfw
> 	  400484:       b8 00 00 00 00          mov    $0x0,%eax
> 	  400489:       c9                      leaveq
> 	  40048a:       c3                      retq

Yes, that one works as well.

> And in any case it would be better to re-use auprobe->fixups.

Okay.

> Oleg.
>

Sebastian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/