Celeste Liu <uwu@xxxxxxxxxxxxxxxxx> writes: > 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/ > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Celeste Liu <uwu@xxxxxxxxxxxxxxxxx> > --- > arch/riscv/kernel/ptrace.c | 32 ++++++++++++++++++++++++++++++++ > include/uapi/linux/elf.h | 1 + > 2 files changed, 33 insertions(+) > > diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c > index ea67e9fb7a583683b922fe2c017ea61f3bc848db..18ce07ffb27bb1180667769eed800f6fdf96c083 100644 > --- a/arch/riscv/kernel/ptrace.c > +++ b/arch/riscv/kernel/ptrace.c > @@ -31,6 +31,7 @@ enum riscv_regset { > #ifdef CONFIG_RISCV_ISA_SUPM > REGSET_TAGGED_ADDR_CTRL, > #endif > + REGSET_ORIG_A0, > }; > > static int riscv_gpr_get(struct task_struct *target, > @@ -184,6 +185,29 @@ static int tagged_addr_ctrl_set(struct task_struct *target, > } > #endif > > +static int riscv_orig_a0_get(struct task_struct *target, > + const struct user_regset *regset, > + struct membuf to) > +{ > + return membuf_store(&to, task_pt_regs(target)->orig_a0); > +} > + > +static int riscv_orig_a0_set(struct task_struct *target, > + const struct user_regset *regset, > + unsigned int pos, unsigned int count, > + const void *kbuf, const void __user *ubuf) > +{ > + unsigned long orig_a0 = task_pt_regs(target)->orig_a0; > + int ret; > + > + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &orig_a0, 0, -1); > + if (ret) > + return ret; > + > + task_pt_regs(target)->orig_a0 = orig_a0; > + return ret; Nit: Could be return 0, for readability. Regardless, Reviewed-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
