linux-kernel - Re: [patch 12/26] Xen-paravirt_ops: Fix patch site clobbers to include return register

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Date:	Thu, 01 Mar 2007 16:52:57 -0800
From:	Zachary Amsden <zach@...are.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	Andi Kleen <ak@....de>, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, virtualization@...ts.osdl.org,
	xen-devel@...ts.xensource.com, Chris Wright <chrisw@...s-sol.org>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [patch 12/26] Xen-paravirt_ops: Fix patch site clobbers to include
 return register

Jeremy Fitzhardinge wrote:
> Zachary Amsden wrote:
>   
>> Jeremy Fitzhardinge wrote:
>>     
>>> Fix a few clobbers to include the return register.  The clobbers set
>>> is the set of all registers modified (or may be modified) by the code
>>> snippet, regardless of whether it was deliberate or accidental.
>>>
>>> Signed-off-by: Jeremy Fitzhardinge <jeremy@...source.com>
>>> Cc: Rusty Russell <rusty@...tcorp.com.au>
>>> Cc: Zachary Amsden <zach@...are.com>
>>>
>>> ---
>>>  include/asm-i386/paravirt.h |    4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> ===================================================================
>>> --- a/include/asm-i386/paravirt.h
>>> +++ b/include/asm-i386/paravirt.h
>>> @@ -556,7 +556,7 @@ static inline unsigned long __raw_local_
>>>                         "popl %%edx; popl %%ecx")
>>>                   : "=a"(f): "m"(paravirt_ops.save_fl),
>>>                     paravirt_type(PARAVIRT_PATCH(save_fl)),
>>> -                   paravirt_clobber(CLBR_NONE)
>>> +                   paravirt_clobber(CLBR_EAX)
>>>                   : "memory", "cc");
>>>      return f;
>>>   
>>>       
>> Has this been tested on older gcc's?  I seem to recall them barfing
>> over things like this.
>>     
>
> Things like what?  Do you mean the %[foo] asm parameter syntax?  I think
> those versions are no longer supported - Arjan posted a patch a few days
> ago to convert a pile of asms to this form.  Or do you mean something else?
>   

I meant having an output in the clobber list, I didn't know we were 
dropping support for older versions already.

Zach
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