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

["H. Peter Anvin" <hpa@xxxxxxxxx>]

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



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