On Sat, Jul 28, 2018 at 1:25 AM, Uros Bizjak <ubiz...@gmail.com> wrote: > On Fri, Jul 27, 2018 at 11:37 AM, Richard Earnshaw > <richard.earns...@arm.com> wrote: >> >> This patch adds a speculation barrier for x86, based on my >> understanding of the required mitigation for that CPU, which is to use >> an lfence instruction. >> >> This patch needs some review by an x86 expert and if adjustments are >> needed, I'd appreciate it if they could be picked up by the port >> maintainer. This is supposed to serve as an example of how to deploy >> the new __builtin_speculation_safe_value() intrinsic on this >> architecture. >> >> * config/i386/i386.md (unspecv): Add UNSPECV_SPECULATION_BARRIER. >> (speculation_barrier): New insn. > > The implementation is OK, but someone from Intel (CC'd) should clarify > if lfence is the correct insn. >
I checked with our people. lfence is OK. Thanks. -- H.J.
