Re: [Xen-devel] [PATCH v3 4/4] x86/asm: Rewrite sync_core() to use IRET-to-self

[H. Peter Anvin]

On 12/06/16 00:46, Jan Beulich wrote:
>> +
>> +#ifdef CONFIG_X86_32
>> +	asm volatile (
>> +		"pushfl\n\t"
>> +		"pushl %%cs\n\t"
>> +		"pushl $1f\n\t"
>> +		"iret\n\t"
>> +		"1:"
>> +		: "+r" (__sp) : : "cc", "memory");
> 
> I don't thing EFLAGS (i.e. "cc") gets modified anywhere here. And
> the memory clobber would perhaps better be pulled out into an
> explicit barrier() invocation (making it more obvious what it's needed
> for)?
> 

Not to mention "cc" doesn't do anything on x86 at all.

	-hpa