On 11/29/22 03:37, Hongtao Liu wrote: > On Mon, Nov 28, 2022 at 10:40 PM Martin Liška <mli...@suse.cz> wrote: >> >> On 11/11/22 02:26, liuhongt via Gcc-patches wrote: >>> 2 years ago, ARM folks support HWASAN[1] in GCC[2], and introduced >>> several >>> target hooks(Many thanks to their work) so other backends can do similar >>> things if they have similar feature. >>> Intel LAM(linear Address Masking)[3 Charpter 14] supports similar >>> feature with >>> the upper bits of pointers can be used as metadata, LAM support two modes: >>> LAM_U48:bits 48-62 can be used as metadata >>> LAM_U57:bits 57-62 can be used as metedata. >>> >>> These 2 patches mainly support those target hooks, but HWASAN is not really >>> enabled until the final decision for the LAM kernel interface which may take >>> quite a long time. We have verified our patches with a "fake" interface >>> locally[4], and >>> decided to push the backend patches to the GCC13 to make other HWASAN >>> developper's work >>> easy. >> >> Hello. >> >> A few random comments I noticed: >> >> 1) please document the new target -mlam in extend.texi > I will.
Thanks. >> 2) the description speaks about bits [48-62] or [57-62], can explain why the >> patch contains: >> > Kernel will use bit 63 for special purposes, and here we want to > extract the tag by shifting right the pointer 57 bits, and need to > manually mask off bit63. And thanks for the explanation. Martin >> + /* Mask off bit63 when LAM_U57. */ >> + if (ix86_lam_type == lam_u57) >> ? >> >> 3) Shouldn't the -lman option emit GNU_PROPERTY_X86_FEATURE_1_LAM_U57 or >> GNU_PROPERTY_X86_FEATURE_1_LAM_U48 >> .gnu.property note? >> >> 4) Can you please explain Florian's comment here: >> https://gitlab.com/x86-psABIs/x86-64-ABI/-/merge_requests/13#note_1181396487 >> >> Thanks, >> Martin >> >>> >>> [1] https://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html >>> [2] https://gcc.gnu.org/pipermail/gcc-patches/2020-November/557857.html >>> [3] >>> https://www.intel.com/content/dam/develop/external/us/en/documents/architecture-instruction-set-extensions-programming-reference.pdf >>> [4] https://gitlab.com/x86-gcc/gcc/-/tree/users/intel/lam/master >>> >>> >>> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}. >>> Ok for trunk? >>> >>> liuhongt (2): >>> Implement hwasan target_hook. >>> Enable hwasan for x86-64. >>> >>> gcc/config/i386/i386-expand.cc | 12 ++++ >>> gcc/config/i386/i386-options.cc | 3 + >>> gcc/config/i386/i386-opts.h | 6 ++ >>> gcc/config/i386/i386-protos.h | 2 + >>> gcc/config/i386/i386.cc | 123 ++++++++++++++++++++++++++++++++ >>> gcc/config/i386/i386.opt | 16 +++++ >>> libsanitizer/configure.tgt | 1 + >>> 7 files changed, 163 insertions(+) >>> >> > >
