On 10/09/2015 09:48 PM, Andy Lutomirski wrote:
> Anyway, it's still a win, but I'll keep playing. There may be even
> better ways to do this.
Such as this?
Drop OR, check for cleared IF here:
testl $X86_EFLAGS_NT, EFLAGS(%rsp)
jnz sysenter_fix_flags
testl $X86_EFLAGS_IF, EFLAGS(%rsp)
jz sysenter_fix_flags
sysenter_flags_fixed:
and make sysenter_fix_flags code set IF in addition to TF clearing.
This way, we don't even have an unconditional RMW op.
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