bpf: Add test ops for BPF_PROG_TYPE_TRACING

The current fexit and fentry tests rely on a different program to
exercise the functions they attach to. Instead of doing this, implement
the test operations for tracing which will also be used for
BPF_MODIFY_RETURN in a subsequent patch.

Also, clean up the fexit test to use the generated skeleton.

Signed-off-by: KP Singh <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Acked-by: Andrii Nakryiko <[e-mail]>
Acked-by: Daniel Borkmann <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

include/linux/bpf.h

···
 			  union bpf_attr __user *uattr);
 int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 			  union bpf_attr __user *uattr);
+int bpf_prog_test_run_tracing(struct bpf_prog *prog,
+			      const union bpf_attr *kattr,
+			      union bpf_attr __user *uattr);
 int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 				     const union bpf_attr *kattr,
 				     union bpf_attr __user *uattr);
···
 static inline int bpf_prog_test_run_skb(struct bpf_prog *prog,
 					const union bpf_attr *kattr,
 					union bpf_attr __user *uattr)
+{
+	return -ENOTSUPP;
+}
+
+static inline int bpf_prog_test_run_tracing(struct bpf_prog *prog,
+					    const union bpf_attr *kattr,
+					    union bpf_attr __user *uattr)
 {
 	return -ENOTSUPP;
 }

kernel/trace/bpf_trace.c

···
 };
 
 const struct bpf_prog_ops tracing_prog_ops = {
+	.test_run = bpf_prog_test_run_tracing,
 };
 
 static bool raw_tp_writable_prog_is_valid_access(int off, int size,

net/bpf/test_run.c

···
 		kfree(data);
 		return ERR_PTR(-EFAULT);
 	}
-	if (bpf_fentry_test1(1) != 2 ||
-	    bpf_fentry_test2(2, 3) != 5 ||
-	    bpf_fentry_test3(4, 5, 6) != 15 ||
-	    bpf_fentry_test4((void *)7, 8, 9, 10) != 34 ||
-	    bpf_fentry_test5(11, (void *)12, 13, 14, 15) != 65 ||
-	    bpf_fentry_test6(16, (void *)17, 18, 19, (void *)20, 21) != 111) {
-		kfree(data);
-		return ERR_PTR(-EFAULT);
-	}
+
 	return data;
+}
+
+int bpf_prog_test_run_tracing(struct bpf_prog *prog,
+			      const union bpf_attr *kattr,
+			      union bpf_attr __user *uattr)
+{
+	int err = -EFAULT;
+
+	switch (prog->expected_attach_type) {
+	case BPF_TRACE_FENTRY:
+	case BPF_TRACE_FEXIT:
+		if (bpf_fentry_test1(1) != 2 ||
+		    bpf_fentry_test2(2, 3) != 5 ||
+		    bpf_fentry_test3(4, 5, 6) != 15 ||
+		    bpf_fentry_test4((void *)7, 8, 9, 10) != 34 ||
+		    bpf_fentry_test5(11, (void *)12, 13, 14, 15) != 65 ||
+		    bpf_fentry_test6(16, (void *)17, 18, 19, (void *)20, 21) != 111)
+			goto out;
+		break;
+	default:
+		goto out;
+	}
+
+	err = 0;
+out:
+	trace_bpf_test_finish(&err);
+	return err;
 }
 
 static void *bpf_ctx_init(const union bpf_attr *kattr, u32 max_size)

tools/testing/selftests/bpf/prog_tests/fentry_fexit.c

···
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2019 Facebook */
 #include <test_progs.h>
-#include "test_pkt_access.skel.h"
 #include "fentry_test.skel.h"
 #include "fexit_test.skel.h"
 
 void test_fentry_fexit(void)
 {
-	struct test_pkt_access *pkt_skel = NULL;
 	struct fentry_test *fentry_skel = NULL;
 	struct fexit_test *fexit_skel = NULL;
 	__u64 *fentry_res, *fexit_res;
 	__u32 duration = 0, retval;
-	int err, pkt_fd, i;
+	int err, prog_fd, i;
 
-	pkt_skel = test_pkt_access__open_and_load();
-	if (CHECK(!pkt_skel, "pkt_skel_load", "pkt_access skeleton failed\n"))
-		return;
 	fentry_skel = fentry_test__open_and_load();
 	if (CHECK(!fentry_skel, "fentry_skel_load", "fentry skeleton failed\n"))
 		goto close_prog;
···
 	if (CHECK(err, "fexit_attach", "fexit attach failed: %d\n", err))
 		goto close_prog;
 
-	pkt_fd = bpf_program__fd(pkt_skel->progs.test_pkt_access);
-	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6),
+	prog_fd = bpf_program__fd(fexit_skel->progs.test1);
+	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
 				NULL, NULL, &retval, &duration);
 	CHECK(err || retval, "ipv6",
 	      "err %d errno %d retval %d duration %d\n",
···
 	}
 
 close_prog:
-	test_pkt_access__destroy(pkt_skel);
 	fentry_test__destroy(fentry_skel);
 	fexit_test__destroy(fexit_skel);
 }

tools/testing/selftests/bpf/prog_tests/fentry_test.c

···
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2019 Facebook */
 #include <test_progs.h>
-#include "test_pkt_access.skel.h"
 #include "fentry_test.skel.h"
 
 void test_fentry_test(void)
 {
-	struct test_pkt_access *pkt_skel = NULL;
 	struct fentry_test *fentry_skel = NULL;
-	int err, pkt_fd, i;
+	int err, prog_fd, i;
 	__u32 duration = 0, retval;
 	__u64 *result;
 
-	pkt_skel = test_pkt_access__open_and_load();
-	if (CHECK(!pkt_skel, "pkt_skel_load", "pkt_access skeleton failed\n"))
-		return;
 	fentry_skel = fentry_test__open_and_load();
 	if (CHECK(!fentry_skel, "fentry_skel_load", "fentry skeleton failed\n"))
 		goto cleanup;
···
 	if (CHECK(err, "fentry_attach", "fentry attach failed: %d\n", err))
 		goto cleanup;
 
-	pkt_fd = bpf_program__fd(pkt_skel->progs.test_pkt_access);
-	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6),
+	prog_fd = bpf_program__fd(fentry_skel->progs.test1);
+	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
 				NULL, NULL, &retval, &duration);
-	CHECK(err || retval, "ipv6",
+	CHECK(err || retval, "test_run",
 	      "err %d errno %d retval %d duration %d\n",
 	      err, errno, retval, duration);
 
···
 
 cleanup:
 	fentry_test__destroy(fentry_skel);
-	test_pkt_access__destroy(pkt_skel);
 }

tools/testing/selftests/bpf/prog_tests/fexit_test.c

···
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2019 Facebook */
 #include <test_progs.h>
+#include "fexit_test.skel.h"
 
 void test_fexit_test(void)
 {
-	struct bpf_prog_load_attr attr = {
-		.file = "./fexit_test.o",
-	};
-
-	char prog_name[] = "fexit/bpf_fentry_testX";
-	struct bpf_object *obj = NULL, *pkt_obj;
-	int err, pkt_fd, kfree_skb_fd, i;
-	struct bpf_link *link[6] = {};
-	struct bpf_program *prog[6];
+	struct fexit_test *fexit_skel = NULL;
+	int err, prog_fd, i;
 	__u32 duration = 0, retval;
-	struct bpf_map *data_map;
-	const int zero = 0;
-	u64 result[6];
+	__u64 *result;
 
-	err = bpf_prog_load("./test_pkt_access.o", BPF_PROG_TYPE_SCHED_CLS,
-			    &pkt_obj, &pkt_fd);
-	if (CHECK(err, "prog_load sched cls", "err %d errno %d\n", err, errno))
-		return;
-	err = bpf_prog_load_xattr(&attr, &obj, &kfree_skb_fd);
-	if (CHECK(err, "prog_load fail", "err %d errno %d\n", err, errno))
-		goto close_prog;
+	fexit_skel = fexit_test__open_and_load();
+	if (CHECK(!fexit_skel, "fexit_skel_load", "fexit skeleton failed\n"))
+		goto cleanup;
 
-	for (i = 0; i < 6; i++) {
-		prog_name[sizeof(prog_name) - 2] = '1' + i;
-		prog[i] = bpf_object__find_program_by_title(obj, prog_name);
-		if (CHECK(!prog[i], "find_prog", "prog %s not found\n", prog_name))
-			goto close_prog;
-		link[i] = bpf_program__attach_trace(prog[i]);
-		if (CHECK(IS_ERR(link[i]), "attach_trace", "failed to link\n"))
-			goto close_prog;
-	}
-	data_map = bpf_object__find_map_by_name(obj, "fexit_te.bss");
-	if (CHECK(!data_map, "find_data_map", "data map not found\n"))
-		goto close_prog;
+	err = fexit_test__attach(fexit_skel);
+	if (CHECK(err, "fexit_attach", "fexit attach failed: %d\n", err))
+		goto cleanup;
 
-	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6),
+	prog_fd = bpf_program__fd(fexit_skel->progs.test1);
+	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
 				NULL, NULL, &retval, &duration);
-	CHECK(err || retval, "ipv6",
+	CHECK(err || retval, "test_run",
 	      "err %d errno %d retval %d duration %d\n",
 	      err, errno, retval, duration);
 
-	err = bpf_map_lookup_elem(bpf_map__fd(data_map), &zero, &result);
-	if (CHECK(err, "get_result",
-		  "failed to get output data: %d\n", err))
-		goto close_prog;
+	result = (__u64 *)fexit_skel->bss;
+	for (i = 0; i < 6; i++) {
+		if (CHECK(result[i] != 1, "result",
+			  "fexit_test%d failed err %lld\n", i + 1, result[i]))
+			goto cleanup;
+	}
 
-	for (i = 0; i < 6; i++)
-		if (CHECK(result[i] != 1, "result", "bpf_fentry_test%d failed err %ld\n",
-			  i + 1, result[i]))
-			goto close_prog;
-
-close_prog:
-	for (i = 0; i < 6; i++)
-		if (!IS_ERR_OR_NULL(link[i]))
-			bpf_link__destroy(link[i]);
-	bpf_object__close(obj);
-	bpf_object__close(pkt_obj);
+cleanup:
+	fexit_test__destroy(fexit_skel);
 }