selftest/bpf: centralize libbpf logging management for test_progs

Make test_progs test runner own libbpf logging. Also introduce two
levels of verbosity: -v and -vv. First one will be used in subsequent
patches to enable test log output always. Second one increases verbosity
level of libbpf logging further to include debug output as well.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -70,10 +70,11 @@ void test_bpf_verif_scale(void)
 	const char *cg_sysctl[] = {
 		"./test_sysctl_loop1.o", "./test_sysctl_loop2.o",
 	};
+	libbpf_print_fn_t old_print_fn = NULL;
 	int err, i;
 
 	if (verifier_stats)
-		libbpf_set_print(libbpf_debug_print);
+		old_print_fn = libbpf_set_print(libbpf_debug_print);
 
 	err = check_load("./loop3.o", BPF_PROG_TYPE_RAW_TRACEPOINT);
 	printf("test_scale:loop3:%s\n", err ? (error_cnt--, "OK") : "FAIL");
@@ -97,4 +98,7 @@ void test_bpf_verif_scale(void)
 
 	err = check_load("./test_seg6_loop.o", BPF_PROG_TYPE_LWT_SEG6LOCAL);
 	printf("test_scale:test_seg6_loop:%s\n", err ? "FAIL" : "OK");
+
+	if (verifier_stats)
+		libbpf_set_print(old_print_fn);
 }

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

 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 
-static int libbpf_debug_print(enum libbpf_print_level level,
-			      const char *format, va_list args)
-{
-	if (level == LIBBPF_DEBUG)
-		return 0;
-
-	return vfprintf(stderr, format, args);
-}
-
 void test_reference_tracking(void)
 {
 	const char *file = "./test_sk_lookup_kern.o";
@@ -36,9 +27,11 @@ void test_reference_tracking(void)
 
 		/* Expect verifier failure if test name has 'fail' */
 		if (strstr(title, "fail") != NULL) {
-			libbpf_set_print(NULL);
+			libbpf_print_fn_t old_print_fn;
+
+			old_print_fn = libbpf_set_print(NULL);
 			err = !bpf_program__load(prog, "GPL", 0);
-			libbpf_set_print(libbpf_debug_print);
+			libbpf_set_print(old_print_fn);
 		} else {
 			err = bpf_program__load(prog, "GPL", 0);
 		}

tools/testing/selftests/bpf/test_progs.c

@@ -186,6 +186,8 @@ enum ARG_KEYS {
 	ARG_TEST_NUM = 'n',
 	ARG_TEST_NAME = 't',
 	ARG_VERIFIER_STATS = 's',
+
+	ARG_VERBOSE = 'v',
 };
 	
 static const struct argp_option opts[] = {
@@ -195,6 +197,8 @@ static const struct argp_option opts[] = {
 	  "Run tests with names containing NAME" },
 	{ "verifier-stats", ARG_VERIFIER_STATS, NULL, 0,
 	  "Output verifier statistics", },
+	{ "verbose", ARG_VERBOSE, "LEVEL", OPTION_ARG_OPTIONAL,
+	  "Verbose output (use -vv for extra verbose output)" },
 	{},
 };
 
@@ -202,12 +206,22 @@ struct test_env {
 	int test_num_selector;
 	const char *test_name_selector;
 	bool verifier_stats;
+	bool verbose;
+	bool very_verbose;
 };
 
 static struct test_env env = {
 	.test_num_selector = -1,
 };
 
+static int libbpf_print_fn(enum libbpf_print_level level,
+			   const char *format, va_list args)
+{
+	if (!env.very_verbose && level == LIBBPF_DEBUG)
+		return 0;
+	return vfprintf(stderr, format, args);
+}
+
 static error_t parse_arg(int key, char *arg, struct argp_state *state)
 {
 	struct test_env *env = state->input;
@@ -229,6 +243,19 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	case ARG_VERIFIER_STATS:
 		env->verifier_stats = true;
 		break;
+	case ARG_VERBOSE:
+		if (arg) {
+			if (strcmp(arg, "v") == 0) {
+				env->very_verbose = true;
+			} else {
+				fprintf(stderr,
+					"Unrecognized verbosity setting ('%s'), only -v and -vv are supported\n",
+					arg);
+				return -EINVAL;
+			}
+		}
+		env->verbose = true;
+		break;
 	case ARGP_KEY_ARG:
 		argp_usage(state);
 		break;
@@ -255,6 +282,8 @@ int main(int argc, char **argv)
 	if (err)
 		return err;
 
+	libbpf_set_print(libbpf_print_fn);
+
 	srand(time(NULL));
 
 	jit_enabled = is_jit_enabled();