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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Bastian Blank <bastian@waldi.eu.org>,
	Ingo Molnar <mingo@redhat.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Stable Kernel <stable@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Xen-devel <xen-devel@lists.xensource.com>
Subject: Re: [Xen-devel] Re: [PATCH] xen: Disable stack protector for irq helper
Date: Mon, 05 Oct 2009 17:36:02 -0700	[thread overview]
Message-ID: <4ACA90F2.1060909@goop.org> (raw)
In-Reply-To: <20091005224310.GA32144@wavehammer.waldi.eu.org>

On 10/05/09 15:43, Bastian Blank wrote:
> On Mon, Oct 05, 2009 at 10:21:01AM -0700, Jeremy Fitzhardinge wrote:
>   
>>> Save all caller-saved registers on x86_32 for the paravirt callee saved
>>> registers.
>>>       
>> That looks better, but it is still overkill.  We only need to save the
>> set of registers the ABI requires the callee to preserve.  What
>> additional register(s) gets clobbered by stack-protector that need to be
>> saved?
>>     
> Well, exactly the two, ecx and edx. eax is still clobbered by the return
> value. Anyway, it works in praxis.

I'm confused.  It already saves ecx, so what else needs saving?

Besides, most of the code in that file isn't used unless you're using a
very old version of Xen; it will generally prefer to use the ones in
xen-asm_X.S.

I have the feeling we haven't really found the root cause of your
problem yet.

Thanks,
    J


WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Bastian Blank <bastian@waldi.eu.org>,
	Ingo Molnar <mingo@redhat.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Stable Kernel <stable@kernel.org>,
	Linux Kernel Mailing List <linux->
Subject: Re: Re: [PATCH] xen: Disable stack protector for irq helper
Date: Mon, 05 Oct 2009 17:36:02 -0700	[thread overview]
Message-ID: <4ACA90F2.1060909@goop.org> (raw)
In-Reply-To: <20091005224310.GA32144@wavehammer.waldi.eu.org>

On 10/05/09 15:43, Bastian Blank wrote:
> On Mon, Oct 05, 2009 at 10:21:01AM -0700, Jeremy Fitzhardinge wrote:
>   
>>> Save all caller-saved registers on x86_32 for the paravirt callee saved
>>> registers.
>>>       
>> That looks better, but it is still overkill.  We only need to save the
>> set of registers the ABI requires the callee to preserve.  What
>> additional register(s) gets clobbered by stack-protector that need to be
>> saved?
>>     
> Well, exactly the two, ecx and edx. eax is still clobbered by the return
> value. Anyway, it works in praxis.

I'm confused.  It already saves ecx, so what else needs saving?

Besides, most of the code in that file isn't used unless you're using a
very old version of Xen; it will generally prefer to use the ones in
xen-asm_X.S.

I have the feeling we haven't really found the root cause of your
problem yet.

Thanks,
    J

  reply	other threads:[~2009-10-06  0:36 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-04 18:30 [PATCH] xen: Disable stack protector for irq helper Bastian Blank
2009-10-04 18:30 ` Bastian Blank
2009-10-04 23:06 ` Jeremy Fitzhardinge
2009-10-04 23:06   ` Jeremy Fitzhardinge
2009-10-05  1:35   ` Bastian Blank
2009-10-05  1:35     ` Bastian Blank
2009-10-05 17:21     ` Jeremy Fitzhardinge
2009-10-05 17:21       ` Jeremy Fitzhardinge
2009-10-05 22:43       ` [Xen-devel] " Bastian Blank
2009-10-05 22:43         ` Bastian Blank
2009-10-06  0:36         ` Jeremy Fitzhardinge [this message]
2009-10-06  0:36           ` Jeremy Fitzhardinge
2009-10-06  3:30           ` [Xen-devel] " Bastian Blank
2009-10-06  3:30             ` Bastian Blank
2009-10-06 19:01             ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-06 19:01               ` Jeremy Fitzhardinge
2009-10-07 16:35               ` [Xen-devel] " Bastian Blank
2009-10-07 16:35                 ` Bastian Blank
2009-10-08  0:33                 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-08  0:33                   ` Jeremy Fitzhardinge
2009-10-12 20:52                   ` [Xen-devel] " Ingo Molnar
2009-10-12 20:52                     ` Ingo Molnar
2009-10-12 21:12                     ` [Xen-devel] " Bastian Blank
2009-10-12 21:12                       ` Bastian Blank
2009-10-12 22:20                       ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-12 22:20                         ` Jeremy Fitzhardinge
2009-10-12 23:32                     ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-12 23:32                       ` Jeremy Fitzhardinge
2009-10-13  7:25                       ` [tip:x86/urgent] x86/paravirt: Use normal calling sequences for irq enable/disable tip-bot for Jeremy Fitzhardinge
2009-10-13  7:25                         ` tip-bot for Jeremy Fitzhardinge
2009-10-05  1:52   ` [PATCH] xen: fbdev frontend needs xenbus frontend Bastian Blank

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