selftests/bpf: Integrate verbose verifier log into test_progs

Add exra level of verboseness, activated by -vvv argument. When -vv is
specified, verbose libbpf and verifier log (level 1) is output, even for
successful tests. With -vvv, verifier log goes to level 2.

This is extremely useful to debug verifier failures, as well as just see the
state and flow of verification. Before this, you'd have to go and modify
load_program()'s source code inside libbpf to specify extra log_level flags,
which is suboptimal to say the least.

Currently -vv and -vvv triggering verifier output is integrated into
test_stub's bpf_prog_load as well as bpf_verif_scale.c tests.

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

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

···
 	return 0;
 }
 
+extern int extra_prog_load_log_flags;
+
 static int check_load(const char *file, enum bpf_prog_type type)
 {
 	struct bpf_prog_load_attr attr;
···
 	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
 	attr.file = file;
 	attr.prog_type = type;
-	attr.log_level = 4;
+	attr.log_level = 4 | extra_prog_load_log_flags;
 	attr.prog_flags = BPF_F_TEST_RND_HI32;
 	err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
 	bpf_object__close(obj);

tools/testing/selftests/bpf/test_progs.c

···
 
 	fflush(stdout); /* exports env.log_buf & env.log_cnt */
 
-	if (env.verbose || test->force_log || failed) {
+	if (env.verbosity > VERBOSE_NONE || test->force_log || failed) {
 		if (env.log_cnt) {
 			env.log_buf[env.log_cnt] = '\0';
 			fprintf(env.stdout, "%s", env.log_buf);
···
 	{ "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)" },
+	  "Verbose output (use -vv or -vvv for progressively verbose output)" },
 	{},
 };
 
 static int libbpf_print_fn(enum libbpf_print_level level,
 			   const char *format, va_list args)
 {
-	if (!env.very_verbose && level == LIBBPF_DEBUG)
+	if (env.verbosity < VERBOSE_VERY && level == LIBBPF_DEBUG)
 		return 0;
 	vprintf(format, args);
 	return 0;
···
 	return 0;
 }
 
+extern int extra_prog_load_log_flags;
+
 static error_t parse_arg(int key, char *arg, struct argp_state *state)
 {
 	struct test_env *env = state->input;
···
 		env->verifier_stats = true;
 		break;
 	case ARG_VERBOSE:
+		env->verbosity = VERBOSE_NORMAL;
 		if (arg) {
 			if (strcmp(arg, "v") == 0) {
-				env->very_verbose = true;
+				env->verbosity = VERBOSE_VERY;
+				extra_prog_load_log_flags = 1;
+			} else if (strcmp(arg, "vv") == 0) {
+				env->verbosity = VERBOSE_SUPER;
+				extra_prog_load_log_flags = 2;
 			} else {
 				fprintf(stderr,
 					"Unrecognized verbosity setting ('%s'), only -v and -vv are supported\n",
···
 				return -EINVAL;
 			}
 		}
-		env->verbose = true;
 		break;
 	case ARGP_KEY_ARG:
 		argp_usage(state);
···
 	env.stdout = stdout;
 	env.stderr = stderr;
 
-	if (env.verbose) {
+	if (env.verbosity > VERBOSE_NONE) {
 		/* nothing to do, output to stdout by default */
 		return;
 	}

tools/testing/selftests/bpf/test_progs.h

···
 #include "trace_helpers.h"
 #include "flow_dissector_load.h"
 
+enum verbosity {
+	VERBOSE_NONE,
+	VERBOSE_NORMAL,
+	VERBOSE_VERY,
+	VERBOSE_SUPER,
+};
+
 struct test_selector {
 	const char *name;
 	bool *num_set;
···
 	struct test_selector test_selector;
 	struct test_selector subtest_selector;
 	bool verifier_stats;
-	bool verbose;
-	bool very_verbose;
+	enum verbosity verbosity;
 
 	bool jit_enabled;
 

tools/testing/selftests/bpf/test_stub.c

···
 #include <bpf/libbpf.h>
 #include <string.h>
 
+int extra_prog_load_log_flags = 0;
+
 int bpf_prog_test_load(const char *file, enum bpf_prog_type type,
 		       struct bpf_object **pobj, int *prog_fd)
 {
···
 	attr.prog_type = type;
 	attr.expected_attach_type = 0;
 	attr.prog_flags = BPF_F_TEST_RND_HI32;
+	attr.log_level = extra_prog_load_log_flags;
 
 	return bpf_prog_load_xattr(&attr, pobj, prog_fd);
 }
···
 	load_attr.license = license;
 	load_attr.kern_version = kern_version;
 	load_attr.prog_flags = BPF_F_TEST_RND_HI32;
+	load_attr.log_level = extra_prog_load_log_flags;
 
 	return bpf_load_program_xattr(&load_attr, log_buf, log_buf_sz);
 }