Re: [Xen-devel] Re: [PATCH] xen: Disable stack protector for irqhelper

[Jeremy Fitzhardinge]

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

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