On Wed, Jan 15, 2025 at 07:13:26PM +0800, Celeste Liu wrote: > The orig_a0 is missing in struct user_regs_struct of riscv, and there is > no way to add it without breaking UAPI. (See Link tag below) > > Like NT_ARM_SYSTEM_CALL do, we add a new regset name NT_RISCV_ORIG_A0 to > access original a0 register from userspace via ptrace API. > > Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@xxxxxxxxx/ > > Signed-off-by: Celeste Liu <uwu@xxxxxxxxxxxxxxxxx> > --- > Changes in v6: > - Fix obsolute comment. > - Copy include/linux/stddef.h to tools/include to use offsetofend in > selftests. > - Link to v5: https://lore.kernel.org/r/20250115-riscv-new-regset-v5-0-d0e6ec031a23@xxxxxxxxxxxxxxxxx > > Changes in v5: > - Fix wrong usage in selftests. > - Link to v4: https://lore.kernel.org/r/20241226-riscv-new-regset-v4-0-4496a29d0436@xxxxxxxxxxxxxxxxx > > Changes in v4: > - Fix a copy paste error in selftest. (Forget to commit...) > - Link to v3: https://lore.kernel.org/r/20241226-riscv-new-regset-v3-0-f5b96465826b@xxxxxxxxxxxxxxxxx > > Changes in v3: > - Use return 0 directly for readability. > - Fix test for modify a0. > - Add Fixes: tag > - Remove useless Cc: stable. > - Selftest will check both a0 and orig_a0, but depends on the > correctness of PTRACE_GET_SYSCALL_INFO. > - Link to v2: https://lore.kernel.org/r/20241203-riscv-new-regset-v2-0-d37da8c0cba6@xxxxxxxxxxxxxxxxx > > Changes in v2: > - Fix integer width. > - Add selftest. > - Link to v1: https://lore.kernel.org/r/20241201-riscv-new-regset-v1-1-c83c58abcc7b@xxxxxxxxxxxxxxxxx > > --- > Celeste Liu (3): > riscv/ptrace: add new regset to access original a0 register > tools: copy include/linux/stddef.h to tools/include > riscv: selftests: Add a ptrace test to verify a0 and orig_a0 access > > arch/riscv/kernel/ptrace.c | 32 +++++ > include/uapi/linux/elf.h | 1 + > tools/include/linux/stddef.h | 85 ++++++++++++ > tools/include/uapi/linux/stddef.h | 6 +- > tools/testing/selftests/riscv/abi/.gitignore | 1 + > tools/testing/selftests/riscv/abi/Makefile | 6 +- > tools/testing/selftests/riscv/abi/ptrace.c | 193 +++++++++++++++++++++++++++ > 7 files changed, 319 insertions(+), 5 deletions(-) > --- > base-commit: 0e287d31b62bb53ad81d5e59778384a40f8b6f56 > change-id: 20241201-riscv-new-regset-d529b952ad0d > > Best regards, > -- > Celeste Liu <uwu@xxxxxxxxxxxxxxxxx> > There is also this series that looks like it will solve this problem by providing an architecture agnostic way of changing syscall args with PTRACE_SET_SYSCALL_INFO [1]. - Charlie [1] https://lore.kernel.org/lkml/20250113170925.GA392@xxxxxxxxxxxx/
