Merge branch 'bpf-support-bpf_get_func_arg-for-bpf_trace_raw_tp'

Menglong Dong says:

====================
bpf: support bpf_get_func_arg() for BPF_TRACE_RAW_TP

Support bpf_get_func_arg() for BPF_TRACE_RAW_TP by getting the function
argument count from "prog->aux->attach_func_proto" during verifier inline.

Changes v5 -> v4:
* some format adjustment in the 1st patch
* v4: https://lore.kernel.org/bpf/20260120073046.324342-1-dongml2@chinatelecom.cn/

Changes v4 -> v3:
* fix the error of using bpf_get_func_arg() for BPF_TRACE_ITER
* v3: https://lore.kernel.org/bpf/20260119023732.130642-1-dongml2@chinatelecom.cn/

Changes v3 -> v2:
* remove unnecessary NULL checking for prog->aux->attach_func_proto
* v2: https://lore.kernel.org/bpf/20260116071739.121182-1-dongml2@chinatelecom.cn/

Changes v2 -> v1:
* for nr_args, skip first 'void *__data' argument in btf_trace_##name
  typedef
* check the result4 and result5 in the selftests
* v1: https://lore.kernel.org/bpf/20260116035024.98214-1-dongml2@chinatelecom.cn/
====================

Link: https://patch.msgid.link/20260121044348.113201-1-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

6 files changed, 87 insertions, 6 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9905ad40f4d3..c7f5234d5fd2 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 bd15ff62490b..0e9635bcd783 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)
diff --git a/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c b/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
index 64a9c95d4acf..fadee95d3ae8 100644
--- a/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
@@ -33,11 +33,14 @@ void test_get_func_args_test(void)
 
 	ASSERT_EQ(topts.retval >> 16, 1, "test_run");
 	ASSERT_EQ(topts.retval & 0xffff, 1234 + 29, "test_run");
+	ASSERT_OK(trigger_module_test_read(1), "trigger_read");
 
 	ASSERT_EQ(skel->bss->test1_result, 1, "test1_result");
 	ASSERT_EQ(skel->bss->test2_result, 1, "test2_result");
 	ASSERT_EQ(skel->bss->test3_result, 1, "test3_result");
 	ASSERT_EQ(skel->bss->test4_result, 1, "test4_result");
+	ASSERT_EQ(skel->bss->test5_result, 1, "test5_result");
+	ASSERT_EQ(skel->bss->test6_result, 1, "test6_result");
 
 cleanup:
 	get_func_args_test__destroy(skel);
diff --git a/tools/testing/selftests/bpf/progs/get_func_args_test.c b/tools/testing/selftests/bpf/progs/get_func_args_test.c
index e0f34a55e697..5b7233afef05 100644
--- a/tools/testing/selftests/bpf/progs/get_func_args_test.c
+++ b/tools/testing/selftests/bpf/progs/get_func_args_test.c
@@ -121,3 +121,47 @@ int BPF_PROG(fexit_test, int _a, int *_b, int _ret)
 	test4_result &= err == 0 && ret == 1234;
 	return 0;
 }
+
+__u64 test5_result = 0;
+SEC("tp_btf/bpf_testmod_fentry_test1_tp")
+int BPF_PROG(tp_test1)
+{
+	__u64 cnt = bpf_get_func_arg_cnt(ctx);
+	__u64 a = 0, z = 0;
+	__s64 err;
+
+	test5_result = cnt == 1;
+
+	err = bpf_get_func_arg(ctx, 0, &a);
+	test5_result &= err == 0 && ((int) a == 1);
+
+	/* not valid argument */
+	err = bpf_get_func_arg(ctx, 1, &z);
+	test5_result &= err == -EINVAL;
+
+	return 0;
+}
+
+__u64 test6_result = 0;
+SEC("tp_btf/bpf_testmod_fentry_test2_tp")
+int BPF_PROG(tp_test2)
+{
+	__u64 cnt = bpf_get_func_arg_cnt(ctx);
+	__u64 a = 0, b = 0, z = 0;
+	__s64 err;
+
+	test6_result = cnt == 2;
+
+	/* valid arguments */
+	err = bpf_get_func_arg(ctx, 0, &a);
+	test6_result &= err == 0 && (int) a == 2;
+
+	err = bpf_get_func_arg(ctx, 1, &b);
+	test6_result &= err == 0 && b == 3;
+
+	/* not valid argument */
+	err = bpf_get_func_arg(ctx, 2, &z);
+	test6_result &= err == -EINVAL;
+
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
index aeef86b3da74..45a5e41f3a92 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
@@ -63,6 +63,16 @@ BPF_TESTMOD_DECLARE_TRACE(bpf_testmod_test_writable_bare,
 	sizeof(struct bpf_testmod_test_writable_ctx)
 );
 
+DECLARE_TRACE(bpf_testmod_fentry_test1,
+	TP_PROTO(int a),
+	TP_ARGS(a)
+);
+
+DECLARE_TRACE(bpf_testmod_fentry_test2,
+	TP_PROTO(int a, u64 b),
+	TP_ARGS(a, b)
+);
+
 #endif /* _BPF_TESTMOD_EVENTS_H */
 
 #undef TRACE_INCLUDE_PATH
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
index d425034b72d3..77a81fa8ec6a 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
@@ -412,11 +412,15 @@ __weak noinline struct file *bpf_testmod_return_ptr(int arg)
 
 noinline int bpf_testmod_fentry_test1(int a)
 {
+	trace_bpf_testmod_fentry_test1_tp(a);
+
 	return a + 1;
 }
 
 noinline int bpf_testmod_fentry_test2(int a, u64 b)
 {
+	trace_bpf_testmod_fentry_test2_tp(a, b);
+
 	return a + b;
 }