On Wed, Nov 30, 2022 at 10:07 PM Martin Liška <mli...@suse.cz> wrote: > > 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. I've committed 2 patches. > >> > >> 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(+) > >>> > >> > > > > >
-- BR, Hongtao
