bpf, tests: Add module parameter test_suite to test_bpf module

After commit 9298e63e ("bpf/tests: Add exhaustive tests of ALU
operand magnitudes"), when modprobe test_bpf.ko with JIT on mips64,
there exists segment fault due to the following reason:

  [...]
  ALU64_MOV_X: all register value magnitudes jited:1
  Break instruction in kernel code[#1]
  [...]

It seems that the related JIT implementations of some test cases
in test_bpf() have problems. At this moment, I do not care about
the segment fault while I just want to verify the test cases of
tail calls.

Based on the above background and motivation, add the following
module parameter test_suite to the test_bpf.ko:

  test_suite=<string>: only the specified test suite will be run, the
  string can be "test_bpf", "test_tail_calls" or "test_skb_segment".

If test_suite is not specified, but test_id, test_name or test_range
is specified, set 'test_bpf' as the default test suite. This is useful
to only test the corresponding test suite when specifying the valid
test_suite string.

Any invalid test suite will result in -EINVAL being returned and no
tests being run. If the test_suite is not specified or specified as
empty string, it does not change the current logic, all of the test
cases will be run.

Here are some test results:

 # dmesg -c
 # modprobe test_bpf
 # dmesg | grep Summary
 test_bpf: Summary: 1009 PASSED, 0 FAILED, [0/997 JIT'ed]
 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]
 test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_suite=test_bpf
 # dmesg | tail -1
 test_bpf: Summary: 1009 PASSED, 0 FAILED, [0/997 JIT'ed]

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_suite=test_tail_calls
 # dmesg
 test_bpf: #0 Tail call leaf jited:0 21 PASS
 [...]
 test_bpf: #7 Tail call error path, index out of range jited:0 32 PASS
 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_suite=test_skb_segment
 # dmesg
 test_bpf: #0 gso_with_rx_frags PASS
 test_bpf: #1 gso_linear_no_head_frag PASS
 test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_id=1
 # dmesg
 test_bpf: test_bpf: set 'test_bpf' as the default test_suite.
 test_bpf: #1 TXA jited:0 54 51 50 PASS
 test_bpf: Summary: 1 PASSED, 0 FAILED, [0/1 JIT'ed]

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_suite=test_bpf test_name=TXA
 # dmesg
 test_bpf: #1 TXA jited:0 54 50 51 PASS
 test_bpf: Summary: 1 PASSED, 0 FAILED, [0/1 JIT'ed]

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_suite=test_tail_calls test_range=6,7
 # dmesg
 test_bpf: #6 Tail call error path, NULL target jited:0 41 PASS
 test_bpf: #7 Tail call error path, index out of range jited:0 32 PASS
 test_bpf: test_tail_calls: Summary: 2 PASSED, 0 FAILED, [0/2 JIT'ed]

 # rmmod test_bpf
 # dmesg -c
 # modprobe test_bpf test_suite=test_skb_segment test_id=1
 # dmesg
 test_bpf: #1 gso_linear_no_head_frag PASS
 test_bpf: test_skb_segment: Summary: 1 PASSED, 0 FAILED

By the way, the above segment fault has been fixed in the latest bpf-next
tree which contains the mips64 JIT rework.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Link: https://lore.kernel.org/bpf/1635384321-28128-1-git-send-email-yangtiezhu@loongson.cn

lib/test_bpf.c

@@ -14316,72 +14316,9 @@ module_param_string(test_name, test_name, sizeof(test_name), 0);
 static int test_id = -1;
 module_param(test_id, int, 0);
 
-static int test_range[2] = { 0, ARRAY_SIZE(tests) - 1 };
+static int test_range[2] = { 0, INT_MAX };
 module_param_array(test_range, int, NULL, 0);
 
-static __init int find_test_index(const char *test_name)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(tests); i++) {
-		if (!strcmp(tests[i].descr, test_name))
-			return i;
-	}
-	return -1;
-}
-
-static __init int prepare_bpf_tests(void)
-{
-	if (test_id >= 0) {
-		/*
-		 * if a test_id was specified, use test_range to
-		 * cover only that test.
-		 */
-		if (test_id >= ARRAY_SIZE(tests)) {
-			pr_err("test_bpf: invalid test_id specified.\n");
-			return -EINVAL;
-		}
-
-		test_range[0] = test_id;
-		test_range[1] = test_id;
-	} else if (*test_name) {
-		/*
-		 * if a test_name was specified, find it and setup
-		 * test_range to cover only that test.
-		 */
-		int idx = find_test_index(test_name);
-
-		if (idx < 0) {
-			pr_err("test_bpf: no test named '%s' found.\n",
-			       test_name);
-			return -EINVAL;
-		}
-		test_range[0] = idx;
-		test_range[1] = idx;
-	} else {
-		/*
-		 * check that the supplied test_range is valid.
-		 */
-		if (test_range[0] >= ARRAY_SIZE(tests) ||
-		    test_range[1] >= ARRAY_SIZE(tests) ||
-		    test_range[0] < 0 || test_range[1] < 0) {
-			pr_err("test_bpf: test_range is out of bound.\n");
-			return -EINVAL;
-		}
-
-		if (test_range[1] < test_range[0]) {
-			pr_err("test_bpf: test_range is ending before it starts.\n");
-			return -EINVAL;
-		}
-	}
-
-	return 0;
-}
-
-static __init void destroy_bpf_tests(void)
-{
-}
-
 static bool exclude_test(int test_id)
 {
 	return test_id < test_range[0] || test_id > test_range[1];
@@ -14553,6 +14490,10 @@ static __init int test_skb_segment(void)
 	for (i = 0; i < ARRAY_SIZE(skb_segment_tests); i++) {
 		const struct skb_segment_test *test = &skb_segment_tests[i];
 
+		cond_resched();
+		if (exclude_test(i))
+			continue;
+
 		pr_info("#%d %s ", i, test->descr);
 
 		if (test_skb_segment_single(test)) {
@@ -14934,6 +14875,8 @@ static __init int test_tail_calls(struct bpf_array *progs)
 		int ret;
 
 		cond_resched();
+		if (exclude_test(i))
+			continue;
 
 		pr_info("#%d %s ", i, test->descr);
 		if (!fp) {
@@ -14966,20 +14909,131 @@ static __init int test_tail_calls(struct bpf_array *progs)
 	return err_cnt ? -EINVAL : 0;
 }
 
+static char test_suite[32];
+module_param_string(test_suite, test_suite, sizeof(test_suite), 0);
+
+static __init int find_test_index(const char *test_name)
+{
+	int i;
+
+	if (!strcmp(test_suite, "test_bpf")) {
+		for (i = 0; i < ARRAY_SIZE(tests); i++) {
+			if (!strcmp(tests[i].descr, test_name))
+				return i;
+		}
+	}
+
+	if (!strcmp(test_suite, "test_tail_calls")) {
+		for (i = 0; i < ARRAY_SIZE(tail_call_tests); i++) {
+			if (!strcmp(tail_call_tests[i].descr, test_name))
+				return i;
+		}
+	}
+
+	if (!strcmp(test_suite, "test_skb_segment")) {
+		for (i = 0; i < ARRAY_SIZE(skb_segment_tests); i++) {
+			if (!strcmp(skb_segment_tests[i].descr, test_name))
+				return i;
+		}
+	}
+
+	return -1;
+}
+
+static __init int prepare_test_range(void)
+{
+	int valid_range;
+
+	if (!strcmp(test_suite, "test_bpf"))
+		valid_range = ARRAY_SIZE(tests);
+	else if (!strcmp(test_suite, "test_tail_calls"))
+		valid_range = ARRAY_SIZE(tail_call_tests);
+	else if (!strcmp(test_suite, "test_skb_segment"))
+		valid_range = ARRAY_SIZE(skb_segment_tests);
+	else
+		return 0;
+
+	if (test_id >= 0) {
+		/*
+		 * if a test_id was specified, use test_range to
+		 * cover only that test.
+		 */
+		if (test_id >= valid_range) {
+			pr_err("test_bpf: invalid test_id specified for '%s' suite.\n",
+			       test_suite);
+			return -EINVAL;
+		}
+
+		test_range[0] = test_id;
+		test_range[1] = test_id;
+	} else if (*test_name) {
+		/*
+		 * if a test_name was specified, find it and setup
+		 * test_range to cover only that test.
+		 */
+		int idx = find_test_index(test_name);
+
+		if (idx < 0) {
+			pr_err("test_bpf: no test named '%s' found for '%s' suite.\n",
+			       test_name, test_suite);
+			return -EINVAL;
+		}
+		test_range[0] = idx;
+		test_range[1] = idx;
+	} else if (test_range[0] != 0 || test_range[1] != INT_MAX) {
+		/*
+		 * check that the supplied test_range is valid.
+		 */
+		if (test_range[0] < 0 || test_range[1] >= valid_range) {
+			pr_err("test_bpf: test_range is out of bound for '%s' suite.\n",
+			       test_suite);
+			return -EINVAL;
+		}
+
+		if (test_range[1] < test_range[0]) {
+			pr_err("test_bpf: test_range is ending before it starts.\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static int __init test_bpf_init(void)
 {
 	struct bpf_array *progs = NULL;
 	int ret;
 
-	ret = prepare_bpf_tests();
+	if (strlen(test_suite) &&
+	    strcmp(test_suite, "test_bpf") &&
+	    strcmp(test_suite, "test_tail_calls") &&
+	    strcmp(test_suite, "test_skb_segment")) {
+		pr_err("test_bpf: invalid test_suite '%s' specified.\n", test_suite);
+		return -EINVAL;
+	}
+
+	/*
+	 * if test_suite is not specified, but test_id, test_name or test_range
+	 * is specified, set 'test_bpf' as the default test suite.
+	 */
+	if (!strlen(test_suite) &&
+	    (test_id != -1 || strlen(test_name) ||
+	    (test_range[0] != 0 || test_range[1] != INT_MAX))) {
+		pr_info("test_bpf: set 'test_bpf' as the default test_suite.\n");
+		strscpy(test_suite, "test_bpf", sizeof(test_suite));
+	}
+
+	ret = prepare_test_range();
 	if (ret < 0)
 		return ret;
 
+	if (!strlen(test_suite) || !strcmp(test_suite, "test_bpf")) {
 		ret = test_bpf();
-	destroy_bpf_tests();
 		if (ret)
 			return ret;
+	}
 
+	if (!strlen(test_suite) || !strcmp(test_suite, "test_tail_calls")) {
 		ret = prepare_tail_call_tests(&progs);
 		if (ret)
 			return ret;
@@ -14987,8 +15041,12 @@ static int __init test_bpf_init(void)
 		destroy_tail_call_tests(progs);
 		if (ret)
 			return ret;
+	}
 
+	if (!strlen(test_suite) || !strcmp(test_suite, "test_skb_segment"))
 		return test_skb_segment();
+
+	return 0;
 }
 
 static void __exit test_bpf_exit(void)