Re: [PATCH]IA64 trap code 16 bytes atomic copy on montecito, take 2

From: bibo,mao <bibo.mao_at_intel.com>
Date: 2006-11-02 16:04:15
Hi Keith,
  thanks for reviewing my patch, I reply inline.

thanks
bibo,mao

Keith Owens wrote:
> "bibo,mao" (on Thu, 02 Nov 2006 11:11:42 +0800) wrote:
>> +#define ia64_ld16(low, addr)						\
>> +	asm volatile(";;ld16 %0=[%1];;":"=r"(low):"r"(addr):"memory")
>> +#define ia64_st16(low, addr)						\
>> +	asm volatile(";;st16 [%1]=%0;;"::"r"(low),"r"(addr):"memory")
>> ...
>> +#define ia64_st16(low, addr)    __st16(__sttype_none, __sthint_none, addr, low)
>> +#define ia64_ld16(low, addr)					\
>> +  	low =  __ld16(__ldtype_none, __ldtype_none, addr)
>> +
> 
> ld16 clobbers ar.csd, that needs to be added to the definition of
> ia64_ld16.
Here I should add some annotation how ld16/st16 works

> 
> ia64_ld16 does not need a memory clobber.
ok, I will delete memory clobber for ia64_ld16.

> 
> Strictly speaking, ia64_st16 does not need a memory clobber.  addr
> should be a write operand (not read as you have it) and gcc should see
> that addr is clobbered.  However we clobber 16 bytes starting at addr
> and I suspect that gcc has no way of telling about the second set of 8
> bytes.  In this case, we may have to stick with a memory clobber on
> ia64_st16.
> 
>> +#define kprobe_update_bundle(dest, src)		\
>> +do {						\
>> +	unsigned long low;			\
>> +	ia64_ld16(low, src);			\
>> +	ia64_st16(low, dest);			\
>> +} while (0)
> 
> Using unsigned long (8 bytes) is misleading for a 16 byte operation.
> Not sure what we can do about that.
more annotation should be suitable, I will add annotation for this macro.
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Received on Thu Nov 02 16:04:24 2006

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