Messages in this thread | | | Date | Thu, 14 Oct 2021 17:43:14 +0300 | From | Ville Syrjälä <> | Subject | Re: [regression] commit d298b03506d3 ("x86/fpu: Restore the masking out of reserved MXCSR bits") |
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On Thu, Oct 14, 2021 at 05:34:14PM +0300, Ville Syrjälä wrote: > On Thu, Oct 14, 2021 at 04:27:07PM +0200, Borislav Petkov wrote: > > On Thu, Oct 14, 2021 at 02:44:33PM +0300, Ville Syrjälä wrote: > > > I have a 32bit installation here that stopped working. Bisected it > > > to commit d298b03506d3 ("x86/fpu: Restore the masking out of reserved > > > MXCSR bits"). > > > > Lemme make sure I understand this correctly: this patch is bad and with > > it reverted it works? > > Yes. > > > > > Because before this patch, the restoring would be a more restrictive > > than before and this patch reverts the code to the old behavior for > > invalid MXCSR bits.
Yeah, it's a bit weird.
Hmm. Actually I just stared at the code a bit more it looks a bit funny. Was it supposed to do this instead?
- fpu->state.fxsave.mxcsr &= ~mxcsr_feature_mask; + fpu->state.fxsave.mxcsr &= mxcsr_feature_mask;
-- Ville Syrjälä Intel
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