Add three static inline helper functions — is_stack_arg_ldx(), is_stack_arg_st(), and is_stack_arg_stx() — that identify r11-based (BPF_REG_PARAMS) instructions used for stack argument passing. These helpers encapsulate the detailed encoding requirements (operand size, register, offset alignment and sign) and hide raw BPF_REG_PARAMS usage from the verifier, making call sites more readable and explicit. A later patch ("bpf: Enable r11 based insns") will wire these helpers into the verifier. Until then, check_and_resolve_insns() rejects any r11-based registers. Signed-off-by: Yonghong Song --- include/linux/filter.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/include/linux/filter.h b/include/linux/filter.h index b77d0b06db6e..918d9b34eac6 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -749,6 +749,27 @@ static inline u32 bpf_prog_run_pin_on_cpu(const struct bpf_prog *prog, return ret; } +static inline bool is_stack_arg_ldx(const struct bpf_insn *insn) +{ + return insn->code == (BPF_LDX | BPF_MEM | BPF_DW) && + insn->src_reg == BPF_REG_PARAMS && + insn->off > 0 && insn->off % 8 == 0; +} + +static inline bool is_stack_arg_st(const struct bpf_insn *insn) +{ + return insn->code == (BPF_ST | BPF_MEM | BPF_DW) && + insn->dst_reg == BPF_REG_PARAMS && + insn->off < 0 && insn->off % 8 == 0; +} + +static inline bool is_stack_arg_stx(const struct bpf_insn *insn) +{ + return insn->code == (BPF_STX | BPF_MEM | BPF_DW) && + insn->dst_reg == BPF_REG_PARAMS && + insn->off < 0 && insn->off % 8 == 0; +} + #define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN struct bpf_skb_data_end { -- 2.53.0-Meta