On 02/13/2017 05:53 AM, Peter Zijlstra wrote: > On Mon, Feb 13, 2017 at 11:47:16AM +0100, Peter Zijlstra wrote: >> That way we'd end up with something like: >> >> asm(" >> push %rdi; >> movslq %edi, %rdi; >> movq __per_cpu_offset(,%rdi,8), %rax; >> cmpb $0, %[offset](%rax); >> setne %al; >> pop %rdi; >> " : : [offset] "i" (((unsigned long)&steal_time) + offsetof(struct >> steal_time, preempted))); >> >> And if we could get rid of the sign extend on edi we could avoid all the >> push-pop nonsense, but I'm not sure I see how to do that (then again, >> this asm foo isn't my strongest point). > Maybe: > > movsql %edi, %rax; > movq __per_cpu_offset(,%rax,8), %rax; > cmpb $0, %[offset](%rax); > setne %al; > > ?
Yes, that looks good to me. Cheers, Longman _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization