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SubjectRe: [PATCH v2 07/36] x86/entry/64/compat: After SYSENTER, move STI after the NT fixup
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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