2025-03-14T14:39:38-07:00, Deepak Gupta debug@rivosinc.com:
Expose a new register type NT_RISCV_USER_CFI for risc-v cfi status and state. Intentionally both landing pad and shadow stack status and state are rolled into cfi state. Creating two different NT_RISCV_USER_XXX would not be useful and wastage of a note type. Enabling or disabling of feature is not allowed via ptrace set interface. However setting `elp` state or setting shadow stack pointer are allowed via ptrace set interface. It is expected `gdb` might have use to fixup `elp` state or `shadow stack` pointer.
Signed-off-by: Deepak Gupta debug@rivosinc.com
arch/riscv/include/uapi/asm/ptrace.h | 18 ++++++++ arch/riscv/kernel/ptrace.c | 83 ++++++++++++++++++++++++++++++++++++ include/uapi/linux/elf.h | 1 + 3 files changed, 102 insertions(+)
diff --git a/arch/riscv/include/uapi/asm/ptrace.h b/arch/riscv/include/uapi/asm/ptrace.h index 659ea3af5680..e6571fba8a8a 100644 --- a/arch/riscv/include/uapi/asm/ptrace.h +++ b/arch/riscv/include/uapi/asm/ptrace.h @@ -131,6 +131,24 @@ struct __sc_riscv_cfi_state { unsigned long ss_ptr; /* shadow stack pointer */ }; +struct __cfi_status {
- /* indirect branch tracking state */
- __u64 lp_en : 1;
- __u64 lp_lock : 1;
- __u64 elp_state : 1;
- /* shadow stack status */
- __u64 shstk_en : 1;
- __u64 shstk_lock : 1;
I remember there was deep hatred towards bitfields in the Linux community, have things changes?
- __u64 rsvd : sizeof(__u64) - 5;
I think you meant "64 - 5".
+};
+struct user_cfi_state {
- struct __cfi_status cfi_status;
- __u64 shstk_ptr;
+};
#endif /* __ASSEMBLY__ */ #endif /* _UAPI_ASM_RISCV_PTRACE_H */ diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c @@ -224,6 +297,16 @@ static const struct user_regset riscv_user_regset[] = { .set = tagged_addr_ctrl_set, }, #endif +#ifdef CONFIG_RISCV_USER_CFI
- [REGSET_CFI] = {
.core_note_type = NT_RISCV_USER_CFI,.align = sizeof(__u64),.n = sizeof(struct user_cfi_state) / sizeof(__u64),.size = sizeof(__u64),
Why not `size = sizeof(struct user_cfi_state)` and `n = 1`?
.regset_get = riscv_cfi_get,.set = riscv_cfi_set,- },
+#endif
[I haven't yet reviewed if a new register is the right thing to do nor looked at the rest of the patch.]