Updated ARM Patches Posted For Mitigating Spectre V1 With GCC Compiler

ARM's Richard Earnshaw has posted a revised version for their months-in-development patch-set for mitigating against unsafe data speculation by the GCC code compiler. This new Spectre V1 mitigation for ARM 64-bit would be exposed via a new -mtrack-speculation compiler switch.

This second version of the Spectre V1 mitigation work led by ARM for the GCC compiler is now available. This new version incorporates the feedback garnered months ago when these initial patches were published and uses a new approach for tracking data speculation to see whether the CPU's control flow speculation matches the data flow calculations.

The -mtrack-speculation compiler switch with these patches is available for AArch64 (64-bit ARM). 32-bit ARM support isn't being worked on at this time since it would be a lot more involved and more intensive due to less registers on the older ARM architecture. The goal of the new compiler switch is to track when the CPU might be speculating incorrectly.

These updated patches can for now be found on the gcc-patches but presumably will be firmed up in time for next year's GCC 9 stable release.