> > Hi HJ, > > > > > -----Original Message----- > > > From: gcc-patches-ow...@gcc.gnu.org [mailto:gcc-patches- > > > ow...@gcc.gnu.org] On Behalf Of H.J. Lu > > > Sent: Sunday, January 14, 2018 9:07 AM > > > To: gcc-patches@gcc.gnu.org > > > Subject: [PATCH 0/5] x86: CVE-2017-5715, aka Spectre > > > > > > This set of patches for GCC 8 mitigates variant #2 of the speculative > > > execution vulnerabilities on x86 processors identified by CVE-2017-5715, > > > aka > > > Spectre. They convert indirect branches and function returns to call and > > > return thunks to avoid speculative execution via indirect call, jmp and > > > ret. > > > > > > H.J. Lu (5): > > > x86: Add -mindirect-branch= > > > x86: Add -mfunction-return= > > > x86: Add -mindirect-branch-register > > > x86: Add 'V' register operand modifier > > > x86: Disallow -mindirect-branch=/-mfunction-return= with > > > -mcmodel=large > > > > Current set of patches don't seem to have any option to generate "lfence" > > as the loop filler in "retpoline", which is required by AMD. > > Can you please clarify the plan. We would like to get this checked-in GCC > > 8. > > Since thunks are output as strings, it is easy to add the option > on the top of patch #1 of the series. I do not fully understand > the reason for choosing pause over lfence for Intel, but if we need > to do both, we need to have command line option (and possibly attribute). > What would be reasonable name for it?
I forgot there is -mindirect-branch-loop for that in the original patchset. So for now we should be happy with having both lfence and pause in there or do we still need it? Honza > > Honza
