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Date: Thu, 29 Jan 2009 01:30:34 -0800
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: Rusty Russell <rusty@rustcorp.com.au>
CC: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Xen-devel <xen-devel@lists.xensource.com>,
       the arch/x86 maintainers <x86@kernel.org>,
       Ian Campbell <ian.campbell@citrix.com>,
       Zachary Amsden <zach@vmware.com>,
       Ravikiran Thirumalai <kiran@scalemp.com>
Subject: Re: [PATCH 4 of 7] x86/paravirt: selectively save/restore regs around
 pvops calls
References: <patchbomb.1233182100@abulafia.goop.org> <5849eb6475c1bbe5a6ca.1233182104@abulafia.goop.org> <200901291917.26601.rusty@rustcorp.com.au>
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Rusty Russell wrote:
> On Thursday 29 January 2009 09:05:04 Jeremy Fitzhardinge wrote:
>   
>> +#define PV_SAVE_REGS(set)			\
>> +	COND_PUSH(set, CLBR_RAX, rax);		\
>> +	COND_PUSH(set, CLBR_RCX, rcx);		\
>> +	COND_PUSH(set, CLBR_RDX, rdx);		\
>> +	COND_PUSH(set, CLBR_RSI, rsi);		\
>> +	COND_PUSH(set, CLBR_RDI, rdi);		\
>> +	COND_PUSH(set, CLBR_R8, r8);		\
>> +	COND_PUSH(set, CLBR_R9, r9);		\
>> +	COND_PUSH(set, CLBR_R10, r10);		\
>> +	COND_PUSH(set, CLBR_R11, r11)
>>     
>
> It's kind of messy.  Can we do something clever here with token pasting?
>   

I tried a few things, but no.  Passing in just RAX, and then pasting 
CLBR_##reg works, and the assembler accepts %RAX - but - the asm code 
also #defines RAX <some stack offset>, so the assembler ends up seeing 
%48.  I considered renaming all the CLBR_ defines to CLBR_rax, but that 
looks unhappy too.  So I stayed with this.

    J
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