From 85c7f914714741de992fc19c2ba673f6c400a584 Mon Sep 17 00:00:00 2001 From: Menglong Dong Date: Wed, 21 Jan 2026 12:43:47 +0800 Subject: [PATCH] bpf: support bpf_get_func_arg() for BPF_TRACE_RAW_TP For now, bpf_get_func_arg() and bpf_get_func_arg_cnt() is not supported by the BPF_TRACE_RAW_TP, which is not convenient to get the argument of the tracepoint, especially for the case that the position of the arguments in a tracepoint can change. The target tracepoint BTF type id is specified during loading time, therefore we can get the function argument count from the function prototype instead of the stack. Signed-off-by: Menglong Dong Acked-by: Yonghong Song Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20260121044348.113201-2-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 22 ++++++++++++++++++---- kernel/trace/bpf_trace.c | 10 ++++++++-- 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9905ad40f4d36..c7f5234d5fd22 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -23741,8 +23741,15 @@ patch_map_ops_generic: /* Implement bpf_get_func_arg inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_arg) { - /* Load nr_args from ctx - 8 */ - insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + if (eatype == BPF_TRACE_RAW_TP) { + int nr_args = btf_type_vlen(prog->aux->attach_func_proto); + + /* skip 'void *__data' in btf_trace_##name() and save to reg0 */ + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args - 1); + } else { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + } insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6); insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3); insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1); @@ -23794,8 +23801,15 @@ patch_map_ops_generic: /* Implement get_func_arg_cnt inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_arg_cnt) { - /* Load nr_args from ctx - 8 */ - insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + if (eatype == BPF_TRACE_RAW_TP) { + int nr_args = btf_type_vlen(prog->aux->attach_func_proto); + + /* skip 'void *__data' in btf_trace_##name() and save to reg0 */ + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args - 1); + } else { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + } new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); if (!new_prog) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index bd15ff62490b0..0e9635bcd783f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1734,11 +1734,17 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_d_path: return &bpf_d_path_proto; case BPF_FUNC_get_func_arg: - return bpf_prog_has_trampoline(prog) ? &bpf_get_func_arg_proto : NULL; + if (bpf_prog_has_trampoline(prog) || + prog->expected_attach_type == BPF_TRACE_RAW_TP) + return &bpf_get_func_arg_proto; + return NULL; case BPF_FUNC_get_func_ret: return bpf_prog_has_trampoline(prog) ? &bpf_get_func_ret_proto : NULL; case BPF_FUNC_get_func_arg_cnt: - return bpf_prog_has_trampoline(prog) ? &bpf_get_func_arg_cnt_proto : NULL; + if (bpf_prog_has_trampoline(prog) || + prog->expected_attach_type == BPF_TRACE_RAW_TP) + return &bpf_get_func_arg_cnt_proto; + return NULL; case BPF_FUNC_get_attach_cookie: if (prog->type == BPF_PROG_TYPE_TRACING && prog->expected_attach_type == BPF_TRACE_RAW_TP) -- 2.47.3