asb added a comment. In D148034#4262991 <https://reviews.llvm.org/D148034#4262991>, @MaskRay wrote:
> In D148034#4260376 <https://reviews.llvm.org/D148034#4260376>, @asb wrote: > >> Will `--[no-]relax-gp` make its way into a minor gcc point release or do we >> need to wait for the next major release? >> >> In terms of this breaking GNU users - isn't it the case that without this >> option, they may get silently broken code when using the shadow call stack? >> Breaking loudly and early seems preferable, though of course it would be >> best if it's easily fixable by e.g. updating to a newer released binutils. > > Yes, `-fsanitize=shadow-call-stack` using gp users will get silently broken > code if linked with GNU ld, unless GNU ld is specified, or `-Wl,--no-relax` > or `-Wl,--no-relax-gp` is specified. > This is an instance of the guideline proposed in > https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/371/commits/bb0df41a4f2626fa039173c2a975039905dce99c > >> For such platforms, care must be taken to ensure all code (compiler >> generated or otherwise) avoids using gp in a way incompatible with the >> platform specific purpose, and that global pointer relaxation is disabled in >> the toolchain. > > Personally I think most `-fsanitize=shadow-call-stack` users do not use GNU > ld, so this incompatibility is actually minor. > > `-fsanitize=shadow-call-stack` is already a quite specific configuration. For > GNU ld users, I think placing the burden more on user education is fine > (sorry, just that we don't have better options). I just wanted to make sure I'm following your suggestion here. Have you come round to the idea of adding `--no-relax-gp` when shadow call stack is enabled and letting it error for users of old GNU tools on the basis that there aren't better options? Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D148034/new/ https://reviews.llvm.org/D148034 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
