Commit 85c7f914 authored by Menglong Dong's avatar Menglong Dong Committed by Alexei Starovoitov
Browse files

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: default avatarMenglong Dong <dongml2@chinatelecom.cn>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20260121044348.113201-2-dongml2@chinatelecom.cn


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent ba335bf3

kernel/bpf/verifier.c

+18 −4
Original line number Diff line number Diff line
@@ -23741,8 +23741,15 @@ static int do_misc_fixups(struct bpf_verifier_env *env) 
		/* Implement bpf_get_func_arg inline. */

		if (prog_type == BPF_PROG_TYPE_TRACING &&

		    insn->imm == BPF_FUNC_get_func_arg) {

			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 @@ static int do_misc_fixups(struct bpf_verifier_env *env)







		/* Implement get_func_arg_cnt inline. */









		if (prog_type == BPF_PROG_TYPE_TRACING &&









		    insn->imm == BPF_FUNC_get_func_arg_cnt) {









			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)

























kernel/trace/bpf_trace.c



+8
−2






























Original line number
Diff line number
Diff line







@@ -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)