On Thu, Sep 03, 2020 at 09:29:54AM -0500, Qing Zhao wrote: > On average, all the options starting with “used_…” (i.e, only the registers > that are used in the routine will be zeroed) have very low runtime overheads, > at most 1.72% for integer benchmarks, and 1.17% for FP benchmarks. > If all the registers will be zeroed, the runtime overhead is bigger, all_arg > is 5.7%, all_gpr is 3.5%, and all is 17.56% for integer benchmarks on > average. > Looks like the overhead of zeroing vector registers is much bigger. > > For ROP mitigation, -fzero-call-used-regs=used-gpr-arg should be enough, the > runtime overhead with this is very small.
That looks great; thanks for doing those tests! (And it seems like these benchmarks are kind of a "worst case" scenario with regard to performance, yes? As in it's mostly tight call loops?) -- Kees Cook
