pengfei added a comment. In D126137#3530777 <https://reviews.llvm.org/D126137#3530777>, @kristof.beyls wrote:
> See https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html, documentation > for "mharden-sls": For AArch64, the options available on the command line are > "retbr", "blr", "none" and "all". > I don't think the options necessarily have to be the same for x86. > But assuming I understand this patch correctly, it seems to me that with this > patch -mharden-sls=all would mean fundamentally slightly different things for > x86 vs arm and aarch64, which could be confusing to users. > IIUC this patch correctly, this patch implements the equivalent of > aarch64/arm's -mharden-sls=retbr (i.e. add a straight-line-speculation > mitigation for returns and indirect jumps, but not for indirect function > calls). > Therefore, I wonder if it wouldn't be better to name this -mharden-sls=retbr > for more consistency across architectures? > Or is the indirect function call case not relevant for x86 (sorry - I'm not > up to speed on the details on the x86 side)? > > Or does `MBB.back().getDesc().isIndirectBranch()` also return True for > indirect calls, in which case my whole remark here can probably be ignored? Thanks for the information! I referred to the AArch64's implementation when I wrote the patch. But the ideas came from GCC. You can find the documentation of X86 on GCC https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html#x86-Options which has already been different from AArch64. The `all` here means 'return' + 'indirect-jmp'. So, yes, there's no indirect function call here. But it matches with GCC X86's options. (A tangential question is do we need these two options expect `all`? @nickdesaulniers) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D126137/new/ https://reviews.llvm.org/D126137 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
