Re: [PATCH 00/12] x86/crypto: Fix RBP usage in several crypto .S files
From: Ingo Molnar
Date: Fri Sep 15 2017 - 01:34:42 EST
* Eric Biggers <ebiggers3@xxxxxxxxx> wrote:
> Hi Josh,
> On Wed, Sep 13, 2017 at 05:33:03PM -0500, Josh Poimboeuf wrote:
> > And here's v2 of the sha512-avx2 patch. It should hopefully gain back
> > most of the performance lost by v1.
> > From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > Subject: [PATCH] x86/crypto: Fix RBP usage in sha512-avx2-asm.S
> > Using RBP as a temporary register breaks frame pointer convention and
> > breaks stack traces when unwinding from an interrupt in the crypto code.
> > Mix things up a little bit to get rid of the RBP usage, without
> > destroying performance. Use RDI instead of RBP for the TBL pointer.
> > That will clobber CTX, so save CTX on the stack and use RDI as CTX
> > before it gets clobbered, and R12 as CTX after it gets clobbered.
> > Also remove the unused y4 variable.
> I tested the v2 patches for both sha256-avx2 and sha512-avx2 on Skylake. They
> both pass the crypto self-tests, and there was no noticable performance
> difference compared to the unpatched versions. Thanks!
Cool, thanks for review and the testing! Can we add your Tested-by + Acked-by tags
to the patches?