Hi, This is a PING for an old patch proposed by H. J. Lu on Oct, 2018:
https://gcc.gnu.org/legacy-ml/gcc-patches/2018-10/msg02079.html This is the first patch of the total 3 patches set, which provides the following new feature: -mzero-caller-saved-regs=[skip|used-gpr|all-gpr|used|all] command-line option and zero_caller_saved_regs("skip|used|all") function attribue: 1. -mzero-caller-saved-regs=skip and zero_caller_saved_regs("skip") Don't zero caller-saved registers upon function return. 2. -mzero-caller-saved-regs=used-gpr and zero_caller_saved_regs("used-gpr") Zero used caller-saved integer registers upon function return. 3. -mzero-caller-saved-regs=all-gpr and zero_caller_saved_regs("all-gpr”) Zero all caller-saved integer registers upon function return. 4. -mzero-caller-saved-regs=used and zero_caller_saved_regs("used") Zero used caller-saved integer and vector registers upon function return. 5. -mzero-caller-saved-regs=all and zero_caller_saved_regs("all") Zero all caller-saved integer and vector registers upon function return. This feature is needed by Linux kernel security improvement. Please refer to Kees Cook’s talk on Linux Plumber Conference 2019: https://outflux.net/slides/2019/lpc/gcc-and-clang.pdf <https://outflux.net/slides/2019/lpc/gcc-and-clang.pdf> Tested on x86-64 with bootstrapping GCC trunk, regression tests exposed several new regressions, these new regressions are fixed by 2 following patches I will send in next two emails. Any comment? thanks. Qing
