Merge branch 'veristat: CSV output, comparison mode, filtering'

Andrii Nakryiko says:

====================

Add three more critical features to veristat tool, which make it sufficient
for a practical work on BPF verifier:

  - CSV output, which allows easier programmatic post-processing of stats;

  - building upon CSV output, veristat now supports comparison mode, in which
    two previously captured CSV outputs from veristat are compared with each
    other in a convenient form;

  - flexible allow/deny filtering using globs for BPF object files and
    programs, allowing to narrow down target BPF programs to be verified.

See individual patches for more details and examples.

v1->v2:
- split out double-free fix into patch #1 (Yonghong);
- fixed typo in verbose flag (Quentin);
- baseline and comparison stats were reversed in output table, fixed that.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 787 insertions, 83 deletions

diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
index 39e6dc41e504..51030234b60a 100644
--- a/tools/testing/selftests/bpf/veristat.c
+++ b/tools/testing/selftests/bpf/veristat.c
@@ -43,23 +43,44 @@ struct stat_specs {
 	int spec_cnt;
 	enum stat_id ids[ALL_STATS_CNT];
 	bool asc[ALL_STATS_CNT];
-	int lens[ALL_STATS_CNT];
+	int lens[ALL_STATS_CNT * 3]; /* 3x for comparison mode */
+};
+
+enum resfmt {
+	RESFMT_TABLE,
+	RESFMT_TABLE_CALCLEN, /* fake format to pre-calculate table's column widths */
+	RESFMT_CSV,
+};
+
+struct filter {
+	char *file_glob;
+	char *prog_glob;
 };
 
 static struct env {
 	char **filenames;
 	int filename_cnt;
 	bool verbose;
+	enum resfmt out_fmt;
+	bool comparison_mode;
 
 	struct verif_stats *prog_stats;
 	int prog_stat_cnt;
 
+	/* baseline_stats is allocated and used only in comparsion mode */
+	struct verif_stats *baseline_stats;
+	int baseline_stat_cnt;
+
 	struct stat_specs output_spec;
 	struct stat_specs sort_spec;
+
+	struct filter *allow_filters;
+	struct filter *deny_filters;
+	int allow_filter_cnt;
+	int deny_filter_cnt;
 } env;
 
-static int libbpf_print_fn(enum libbpf_print_level level,
-		    const char *format, va_list args)
+static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
 {
 	if (!env.verbose)
 		return 0;
@@ -71,19 +92,25 @@ static int libbpf_print_fn(enum libbpf_print_level level,
 const char *argp_program_version = "veristat";
 const char *argp_program_bug_address = "<bpf@vger.kernel.org>";
 const char argp_program_doc[] =
-"veristat    BPF verifier stats collection tool.\n"
+"veristat    BPF verifier stats collection and comparison tool.\n"
 "\n"
-"USAGE: veristat <obj-file> [<obj-file>...]\n";
+"USAGE: veristat <obj-file> [<obj-file>...]\n"
+"   OR: veristat -C <baseline.csv> <comparison.csv>\n";
 
 static const struct argp_option opts[] = {
 	{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" },
 	{ "verbose", 'v', NULL, 0, "Verbose mode" },
-	{ "output", 'o', "SPEC", 0, "Specify output stats" },
+	{ "emit", 'e', "SPEC", 0, "Specify stats to be emitted" },
 	{ "sort", 's', "SPEC", 0, "Specify sort order" },
+	{ "output-format", 'o', "FMT", 0, "Result output format (table, csv), default is table." },
+	{ "compare", 'C', NULL, 0, "Comparison mode" },
+	{ "filter", 'f', "FILTER", 0, "Filter expressions (or @filename for file with expressions)." },
 	{},
 };
 
 static int parse_stats(const char *stats_str, struct stat_specs *specs);
+static int append_filter(struct filter **filters, int *cnt, const char *str);
+static int append_filter_file(const char *path);
 
 static error_t parse_arg(int key, char *arg, struct argp_state *state)
 {
@@ -97,7 +124,7 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	case 'v':
 		env.verbose = true;
 		break;
-	case 'o':
+	case 'e':
 		err = parse_stats(arg, &env.output_spec);
 		if (err)
 			return err;
@@ -107,6 +134,31 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 		if (err)
 			return err;
 		break;
+	case 'o':
+		if (strcmp(arg, "table") == 0) {
+			env.out_fmt = RESFMT_TABLE;
+		} else if (strcmp(arg, "csv") == 0) {
+			env.out_fmt = RESFMT_CSV;
+		} else {
+			fprintf(stderr, "Unrecognized output format '%s'\n", arg);
+			return -EINVAL;
+		}
+		break;
+	case 'C':
+		env.comparison_mode = true;
+		break;
+	case 'f':
+		if (arg[0] == '@')
+			err = append_filter_file(arg + 1);
+		else if (arg[0] == '!')
+			err = append_filter(&env.deny_filters, &env.deny_filter_cnt, arg + 1);
+		else
+			err = append_filter(&env.allow_filters, &env.allow_filter_cnt, arg);
+		if (err) {
+			fprintf(stderr, "Failed to collect program filter expressions: %d\n", err);
+			return err;
+		}
+		break;
 	case ARGP_KEY_ARG:
 		tmp = realloc(env.filenames, (env.filename_cnt + 1) * sizeof(*env.filenames));
 		if (!tmp)
@@ -123,6 +175,156 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	return 0;
 }
 
+static const struct argp argp = {
+	.options = opts,
+	.parser = parse_arg,
+	.doc = argp_program_doc,
+};
+
+
+/* Adapted from perf/util/string.c */
+static bool glob_matches(const char *str, const char *pat)
+{
+	while (*str && *pat && *pat != '*') {
+		if (*str != *pat)
+			return false;
+		str++;
+		pat++;
+	}
+	/* Check wild card */
+	if (*pat == '*') {
+		while (*pat == '*')
+			pat++;
+		if (!*pat) /* Tail wild card matches all */
+			return true;
+		while (*str)
+			if (glob_matches(str++, pat))
+				return true;
+	}
+	return !*str && !*pat;
+}
+
+static bool should_process_file(const char *filename)
+{
+	int i;
+
+	if (env.deny_filter_cnt > 0) {
+		for (i = 0; i < env.deny_filter_cnt; i++) {
+			if (glob_matches(filename, env.deny_filters[i].file_glob))
+				return false;
+		}
+	}
+
+	if (env.allow_filter_cnt == 0)
+		return true;
+
+	for (i = 0; i < env.allow_filter_cnt; i++) {
+		if (glob_matches(filename, env.allow_filters[i].file_glob))
+			return true;
+	}
+
+	return false;
+}
+
+static bool should_process_prog(const char *filename, const char *prog_name)
+{
+	int i;
+
+	if (env.deny_filter_cnt > 0) {
+		for (i = 0; i < env.deny_filter_cnt; i++) {
+			if (glob_matches(filename, env.deny_filters[i].file_glob))
+				return false;
+			if (!env.deny_filters[i].prog_glob)
+				continue;
+			if (glob_matches(prog_name, env.deny_filters[i].prog_glob))
+				return false;
+		}
+	}
+
+	if (env.allow_filter_cnt == 0)
+		return true;
+
+	for (i = 0; i < env.allow_filter_cnt; i++) {
+		if (!glob_matches(filename, env.allow_filters[i].file_glob))
+			continue;
+		/* if filter specifies only filename glob part, it implicitly
+		 * allows all progs within that file
+		 */
+		if (!env.allow_filters[i].prog_glob)
+			return true;
+		if (glob_matches(prog_name, env.allow_filters[i].prog_glob))
+			return true;
+	}
+
+	return false;
+}
+
+static int append_filter(struct filter **filters, int *cnt, const char *str)
+{
+	struct filter *f;
+	void *tmp;
+	const char *p;
+
+	tmp = realloc(*filters, (*cnt + 1) * sizeof(**filters));
+	if (!tmp)
+		return -ENOMEM;
+	*filters = tmp;
+
+	f = &(*filters)[*cnt];
+	f->file_glob = f->prog_glob = NULL;
+
+	/* filter can be specified either as "<obj-glob>" or "<obj-glob>/<prog-glob>" */
+	p = strchr(str, '/');
+	if (!p) {
+		f->file_glob = strdup(str);
+		if (!f->file_glob)
+			return -ENOMEM;
+	} else {
+		f->file_glob = strndup(str, p - str);
+		f->prog_glob = strdup(p + 1);
+		if (!f->file_glob || !f->prog_glob) {
+			free(f->file_glob);
+			free(f->prog_glob);
+			f->file_glob = f->prog_glob = NULL;
+			return -ENOMEM;
+		}
+	}
+
+	*cnt = *cnt + 1;
+	return 0;
+}
+
+static int append_filter_file(const char *path)
+{
+	char buf[1024];
+	FILE *f;
+	int err = 0;
+
+	f = fopen(path, "r");
+	if (!f) {
+		err = -errno;
+		fprintf(stderr, "Failed to open '%s': %d\n", path, err);
+		return err;
+	}
+
+	while (fscanf(f, " %1023[^\n]\n", buf) == 1) {
+		/* lines starting with # are comments, skip them */
+		if (buf[0] == '\0' || buf[0] == '#')
+			continue;
+		/* lines starting with ! are negative match filters */
+		if (buf[0] == '!')
+			err = append_filter(&env.deny_filters, &env.deny_filter_cnt, buf + 1);
+		else
+			err = append_filter(&env.allow_filters, &env.allow_filter_cnt, buf);
+		if (err)
+			goto cleanup;
+	}
+
+cleanup:
+	fclose(f);
+	return err;
+}
+
 static const struct stat_specs default_output_spec = {
 	.spec_cnt = 7,
 	.ids = {
@@ -147,7 +349,7 @@ static struct stat_def {
 	[FILE_NAME] = { "File", {"file_name", "filename", "file"}, true /* asc */ },
 	[PROG_NAME] = { "Program", {"prog_name", "progname", "prog"}, true /* asc */ },
 	[VERDICT] = { "Verdict", {"verdict"}, true /* asc: failure, success */ },
-	[DURATION] = { "Duration, us", {"duration", "dur"}, },
+	[DURATION] = { "Duration (us)", {"duration", "dur"}, },
 	[TOTAL_INSNS] = { "Total insns", {"total_insns", "insns"}, },
 	[TOTAL_STATES] = { "Total states", {"total_states", "states"}, },
 	[PEAK_STATES] = { "Peak states", {"peak_states"}, },
@@ -201,6 +403,20 @@ static int parse_stats(const char *stats_str, struct stat_specs *specs)
 	return 0;
 }
 
+static void free_verif_stats(struct verif_stats *stats, size_t stat_cnt)
+{
+	int i;
+
+	if (!stats)
+		return;
+
+	for (i = 0; i < stat_cnt; i++) {
+		free(stats[i].file_name);
+		free(stats[i].prog_name);
+	}
+	free(stats);
+}
+
 static char verif_log_buf[64 * 1024];
 
 static int parse_verif_log(const char *buf, size_t buf_sz, struct verif_stats *s)
@@ -236,6 +452,9 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
 	int err = 0;
 	void *tmp;
 
+	if (!should_process_prog(basename(filename), bpf_program__name(prog)))
+		return 0;
+
 	tmp = realloc(env.prog_stats, (env.prog_stat_cnt + 1) * sizeof(*env.prog_stats));
 	if (!tmp)
 		return -ENOMEM;
@@ -283,6 +502,9 @@ static int process_obj(const char *filename)
 	LIBBPF_OPTS(bpf_object_open_opts, opts);
 	int err = 0, prog_cnt = 0;
 
+	if (!should_process_file(basename(filename)))
+		return 0;
+
 	old_libbpf_print_fn = libbpf_set_print(libbpf_print_fn);
 
 	obj = bpf_object__open_file(filename, &opts);
@@ -300,7 +522,6 @@ static int process_obj(const char *filename)
 		prog = bpf_object__next_program(obj, NULL);
 		bpf_program__set_autoload(prog, true);
 		process_prog(filename, obj, prog);
-		bpf_object__close(obj);
 		goto cleanup;
 	}
 
@@ -386,7 +607,21 @@ static int cmp_prog_stats(const void *v1, const void *v2)
 #define HEADER_CHAR '-'
 #define COLUMN_SEP "  "
 
-static void output_headers(bool calc_len)
+static void output_header_underlines(void)
+{
+	int i, j, len;
+
+	for (i = 0; i < env.output_spec.spec_cnt; i++) {
+		len = env.output_spec.lens[i];
+
+		printf("%s", i == 0 ? "" : COLUMN_SEP);
+		for (j = 0; j < len; j++)
+			printf("%c", HEADER_CHAR);
+	}
+	printf("\n");
+}
+
+static void output_headers(enum resfmt fmt)
 {
 	int i, len;
 
@@ -394,34 +629,57 @@ static void output_headers(bool calc_len)
 		int id = env.output_spec.ids[i];
 		int *max_len = &env.output_spec.lens[i];
 
-		if (calc_len) {
+		switch (fmt) {
+		case RESFMT_TABLE_CALCLEN:
 			len = snprintf(NULL, 0, "%s", stat_defs[id].header);
 			if (len > *max_len)
 				*max_len = len;
-		} else {
+			break;
+		case RESFMT_TABLE:
 			printf("%s%-*s", i == 0 ? "" : COLUMN_SEP,  *max_len, stat_defs[id].header);
+			if (i == env.output_spec.spec_cnt - 1)
+				printf("\n");
+			break;
+		case RESFMT_CSV:
+			printf("%s%s", i == 0 ? "" : ",", stat_defs[id].names[0]);
+			if (i == env.output_spec.spec_cnt - 1)
+				printf("\n");
+			break;
 		}
 	}
 
-	if (!calc_len)
-		printf("\n");
+	if (fmt == RESFMT_TABLE)
+		output_header_underlines();
 }
 
-static void output_header_underlines(void)
+static void prepare_value(const struct verif_stats *s, enum stat_id id,
+			  const char **str, long *val)
 {
-	int i, j, len;
-
-	for (i = 0; i < env.output_spec.spec_cnt; i++) {
-		len = env.output_spec.lens[i];
-
-		printf("%s", i == 0 ? "" : COLUMN_SEP);
-		for (j = 0; j < len; j++)
-			printf("%c", HEADER_CHAR);
+	switch (id) {
+	case FILE_NAME:
+		*str = s->file_name;
+		break;
+	case PROG_NAME:
+		*str = s->prog_name;
+		break;
+	case VERDICT:
+		*str = s->stats[VERDICT] ? "success" : "failure";
+		break;
+	case DURATION:
+	case TOTAL_INSNS:
+	case TOTAL_STATES:
+	case PEAK_STATES:
+	case MAX_STATES_PER_INSN:
+	case MARK_READ_MAX_LEN:
+		*val = s->stats[id];
+		break;
+	default:
+		fprintf(stderr, "Unrecognized stat #%d\n", id);
+		exit(1);
 	}
-	printf("\n");
 }
 
-static void output_stats(const struct verif_stats *s, bool calc_len)
+static void output_stats(const struct verif_stats *s, enum resfmt fmt, bool last)
 {
 	int i;
 
@@ -431,107 +689,536 @@ static void output_stats(const struct verif_stats *s, bool calc_len)
 		const char *str = NULL;
 		long val = 0;
 
-		switch (id) {
-		case FILE_NAME:
-			str = s->file_name;
-			break;
-		case PROG_NAME:
-			str = s->prog_name;
-			break;
-		case VERDICT:
-			str = s->stats[VERDICT] ? "success" : "failure";
-			break;
-		case DURATION:
-		case TOTAL_INSNS:
-		case TOTAL_STATES:
-		case PEAK_STATES:
-		case MAX_STATES_PER_INSN:
-		case MARK_READ_MAX_LEN:
-			val = s->stats[id];
-			break;
-		default:
-			fprintf(stderr, "Unrecognized stat #%d\n", id);
-			exit(1);
-		}
+		prepare_value(s, id, &str, &val);
 
-		if (calc_len) {
+		switch (fmt) {
+		case RESFMT_TABLE_CALCLEN:
 			if (str)
 				len = snprintf(NULL, 0, "%s", str);
 			else
 				len = snprintf(NULL, 0, "%ld", val);
 			if (len > *max_len)
 				*max_len = len;
-		} else {
+			break;
+		case RESFMT_TABLE:
 			if (str)
 				printf("%s%-*s", i == 0 ? "" : COLUMN_SEP, *max_len, str);
 			else
 				printf("%s%*ld", i == 0 ? "" : COLUMN_SEP,  *max_len, val);
+			if (i == env.output_spec.spec_cnt - 1)
+				printf("\n");
+			break;
+		case RESFMT_CSV:
+			if (str)
+				printf("%s%s", i == 0 ? "" : ",", str);
+			else
+				printf("%s%ld", i == 0 ? "" : ",", val);
+			if (i == env.output_spec.spec_cnt - 1)
+				printf("\n");
+			break;
 		}
 	}
 
-	if (!calc_len)
-		printf("\n");
+	if (last && fmt == RESFMT_TABLE) {
+		output_header_underlines();
+		printf("Done. Processed %d object files, %d programs.\n",
+		       env.filename_cnt, env.prog_stat_cnt);
+	}
 }
 
-int main(int argc, char **argv)
+static int handle_verif_mode(void)
 {
-	static const struct argp argp = {
-		.options = opts,
-		.parser = parse_arg,
-		.doc = argp_program_doc,
-	};
-	int err = 0, i;
-
-	if (argp_parse(&argp, argc, argv, 0, NULL, NULL))
-		return 1;
+	int i, err;
 
 	if (env.filename_cnt == 0) {
 		fprintf(stderr, "Please provide path to BPF object file!\n");
 		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
-		return 1;
+		return -EINVAL;
 	}
 
-	if (env.output_spec.spec_cnt == 0)
-		env.output_spec = default_output_spec;
-	if (env.sort_spec.spec_cnt == 0)
-		env.sort_spec = default_sort_spec;
-
 	for (i = 0; i < env.filename_cnt; i++) {
 		err = process_obj(env.filenames[i]);
 		if (err) {
 			fprintf(stderr, "Failed to process '%s': %d\n", env.filenames[i], err);
-			goto cleanup;
+			return err;
 		}
 	}
 
 	qsort(env.prog_stats, env.prog_stat_cnt, sizeof(*env.prog_stats), cmp_prog_stats);
 
-	/* calculate column widths */
-	output_headers(true);
-	for (i = 0; i < env.prog_stat_cnt; i++) {
-		output_stats(&env.prog_stats[i], true);
+	if (env.out_fmt == RESFMT_TABLE) {
+		/* calculate column widths */
+		output_headers(RESFMT_TABLE_CALCLEN);
+		for (i = 0; i < env.prog_stat_cnt; i++)
+			output_stats(&env.prog_stats[i], RESFMT_TABLE_CALCLEN, false);
 	}
 
 	/* actually output the table */
-	output_headers(false);
-	output_header_underlines();
+	output_headers(env.out_fmt);
 	for (i = 0; i < env.prog_stat_cnt; i++) {
-		output_stats(&env.prog_stats[i], false);
+		output_stats(&env.prog_stats[i], env.out_fmt, i == env.prog_stat_cnt - 1);
 	}
-	output_header_underlines();
-	printf("\n");
 
-	printf("Done. Processed %d object files, %d programs.\n",
-	       env.filename_cnt, env.prog_stat_cnt);
+	return 0;
+}
+
+static int parse_stat_value(const char *str, enum stat_id id, struct verif_stats *st)
+{
+	switch (id) {
+	case FILE_NAME:
+		st->file_name = strdup(str);
+		if (!st->file_name)
+			return -ENOMEM;
+		break;
+	case PROG_NAME:
+		st->prog_name = strdup(str);
+		if (!st->prog_name)
+			return -ENOMEM;
+		break;
+	case VERDICT:
+		if (strcmp(str, "success") == 0) {
+			st->stats[VERDICT] = true;
+		} else if (strcmp(str, "failure") == 0) {
+			st->stats[VERDICT] = false;
+		} else {
+			fprintf(stderr, "Unrecognized verification verdict '%s'\n", str);
+			return -EINVAL;
+		}
+		break;
+	case DURATION:
+	case TOTAL_INSNS:
+	case TOTAL_STATES:
+	case PEAK_STATES:
+	case MAX_STATES_PER_INSN:
+	case MARK_READ_MAX_LEN: {
+		long val;
+		int err, n;
+
+		if (sscanf(str, "%ld %n", &val, &n) != 1 || n != strlen(str)) {
+			err = -errno;
+			fprintf(stderr, "Failed to parse '%s' as integer\n", str);
+			return err;
+		}
+
+		st->stats[id] = val;
+		break;
+	}
+	default:
+		fprintf(stderr, "Unrecognized stat #%d\n", id);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int parse_stats_csv(const char *filename, struct stat_specs *specs,
+			   struct verif_stats **statsp, int *stat_cntp)
+{
+	char line[4096];
+	FILE *f;
+	int err = 0;
+	bool header = true;
+
+	f = fopen(filename, "r");
+	if (!f) {
+		err = -errno;
+		fprintf(stderr, "Failed to open '%s': %d\n", filename, err);
+		return err;
+	}
+
+	*stat_cntp = 0;
+
+	while (fgets(line, sizeof(line), f)) {
+		char *input = line, *state = NULL, *next;
+		struct verif_stats *st = NULL;
+		int col = 0;
+
+		if (!header) {
+			void *tmp;
+
+			tmp = realloc(*statsp, (*stat_cntp + 1) * sizeof(**statsp));
+			if (!tmp) {
+				err = -ENOMEM;
+				goto cleanup;
+			}
+			*statsp = tmp;
+
+			st = &(*statsp)[*stat_cntp];
+			memset(st, 0, sizeof(*st));
+
+			*stat_cntp += 1;
+		}
+
+		while ((next = strtok_r(state ? NULL : input, ",\n", &state))) {
+			if (header) {
+				/* for the first line, set up spec stats */
+				err = parse_stat(next, specs);
+				if (err)
+					goto cleanup;
+				continue;
+			}
+
+			/* for all other lines, parse values based on spec */
+			if (col >= specs->spec_cnt) {
+				fprintf(stderr, "Found extraneous column #%d in row #%d of '%s'\n",
+					col, *stat_cntp, filename);
+				err = -EINVAL;
+				goto cleanup;
+			}
+			err = parse_stat_value(next, specs->ids[col], st);
+			if (err)
+				goto cleanup;
+			col++;
+		}
+
+		if (header) {
+			header = false;
+			continue;
+		}
+
+		if (col < specs->spec_cnt) {
+			fprintf(stderr, "Not enough columns in row #%d in '%s'\n",
+				*stat_cntp, filename);
+			err = -EINVAL;
+			goto cleanup;
+		}
+
+		if (!st->file_name || !st->prog_name) {
+			fprintf(stderr, "Row #%d in '%s' is missing file and/or program name\n",
+				*stat_cntp, filename);
+			err = -EINVAL;
+			goto cleanup;
+		}
+
+		/* in comparison mode we can only check filters after we
+		 * parsed entire line; if row should be ignored we pretend we
+		 * never parsed it
+		 */
+		if (!should_process_prog(st->file_name, st->prog_name)) {
+			free(st->file_name);
+			free(st->prog_name);
+			*stat_cntp -= 1;
+		}
+	}
+
+	if (!feof(f)) {
+		err = -errno;
+		fprintf(stderr, "Failed I/O for '%s': %d\n", filename, err);
+	}
 
 cleanup:
-	for (i = 0; i < env.prog_stat_cnt; i++) {
-		free(env.prog_stats[i].file_name);
-		free(env.prog_stats[i].prog_name);
+	fclose(f);
+	return err;
+}
+
+/* empty/zero stats for mismatched rows */
+static const struct verif_stats fallback_stats = { .file_name = "", .prog_name = "" };
+
+static bool is_key_stat(enum stat_id id)
+{
+	return id == FILE_NAME || id == PROG_NAME;
+}
+
+static void output_comp_header_underlines(void)
+{
+	int i, j, k;
+
+	for (i = 0; i < env.output_spec.spec_cnt; i++) {
+		int id = env.output_spec.ids[i];
+		int max_j = is_key_stat(id) ? 1 : 3;
+
+		for (j = 0; j < max_j; j++) {
+			int len = env.output_spec.lens[3 * i + j];
+
+			printf("%s", i + j == 0 ? "" : COLUMN_SEP);
+
+			for (k = 0; k < len; k++)
+				printf("%c", HEADER_CHAR);
+		}
 	}
-	free(env.prog_stats);
+	printf("\n");
+}
+
+static void output_comp_headers(enum resfmt fmt)
+{
+	static const char *table_sfxs[3] = {" (A)", " (B)", " (DIFF)"};
+	static const char *name_sfxs[3] = {"_base", "_comp", "_diff"};
+	int i, j, len;
+
+	for (i = 0; i < env.output_spec.spec_cnt; i++) {
+		int id = env.output_spec.ids[i];
+		/* key stats don't have A/B/DIFF columns, they are common for both data sets */
+		int max_j = is_key_stat(id) ? 1 : 3;
+
+		for (j = 0; j < max_j; j++) {
+			int *max_len = &env.output_spec.lens[3 * i + j];
+			bool last = (i == env.output_spec.spec_cnt - 1) && (j == max_j - 1);
+			const char *sfx;
+
+			switch (fmt) {
+			case RESFMT_TABLE_CALCLEN:
+				sfx = is_key_stat(id) ? "" : table_sfxs[j];
+				len = snprintf(NULL, 0, "%s%s", stat_defs[id].header, sfx);
+				if (len > *max_len)
+					*max_len = len;
+				break;
+			case RESFMT_TABLE:
+				sfx = is_key_stat(id) ? "" : table_sfxs[j];
+				printf("%s%-*s%s", i + j == 0 ? "" : COLUMN_SEP,
+				       *max_len - (int)strlen(sfx), stat_defs[id].header, sfx);
+				if (last)
+					printf("\n");
+				break;
+			case RESFMT_CSV:
+				sfx = is_key_stat(id) ? "" : name_sfxs[j];
+				printf("%s%s%s", i + j == 0 ? "" : ",", stat_defs[id].names[0], sfx);
+				if (last)
+					printf("\n");
+				break;
+			}
+		}
+	}
+
+	if (fmt == RESFMT_TABLE)
+		output_comp_header_underlines();
+}
+
+static void output_comp_stats(const struct verif_stats *base, const struct verif_stats *comp,
+			      enum resfmt fmt, bool last)
+{
+	char base_buf[1024] = {}, comp_buf[1024] = {}, diff_buf[1024] = {};
+	int i;
+
+	for (i = 0; i < env.output_spec.spec_cnt; i++) {
+		int id = env.output_spec.ids[i], len;
+		int *max_len_base = &env.output_spec.lens[3 * i + 0];
+		int *max_len_comp = &env.output_spec.lens[3 * i + 1];
+		int *max_len_diff = &env.output_spec.lens[3 * i + 2];
+		const char *base_str = NULL, *comp_str = NULL;
+		long base_val = 0, comp_val = 0, diff_val = 0;
+
+		prepare_value(base, id, &base_str, &base_val);
+		prepare_value(comp, id, &comp_str, &comp_val);
+
+		/* normalize all the outputs to be in string buffers for simplicity */
+		if (is_key_stat(id)) {
+			/* key stats (file and program name) are always strings */
+			if (base != &fallback_stats)
+				snprintf(base_buf, sizeof(base_buf), "%s", base_str);
+			else
+				snprintf(base_buf, sizeof(base_buf), "%s", comp_str);
+		} else if (base_str) {
+			snprintf(base_buf, sizeof(base_buf), "%s", base_str);
+			snprintf(comp_buf, sizeof(comp_buf), "%s", comp_str);
+			if (strcmp(base_str, comp_str) == 0)
+				snprintf(diff_buf, sizeof(diff_buf), "%s", "MATCH");
+			else
+				snprintf(diff_buf, sizeof(diff_buf), "%s", "MISMATCH");
+		} else {
+			snprintf(base_buf, sizeof(base_buf), "%ld", base_val);
+			snprintf(comp_buf, sizeof(comp_buf), "%ld", comp_val);
+
+			diff_val = comp_val - base_val;
+			if (base == &fallback_stats || comp == &fallback_stats || base_val == 0) {
+				snprintf(diff_buf, sizeof(diff_buf), "%+ld (%+.2lf%%)",
+					 diff_val, comp_val < base_val ? -100.0 : 100.0);
+			} else {
+				snprintf(diff_buf, sizeof(diff_buf), "%+ld (%+.2lf%%)",
+					 diff_val, diff_val * 100.0 / base_val);
+			}
+		}
+
+		switch (fmt) {
+		case RESFMT_TABLE_CALCLEN:
+			len = strlen(base_buf);
+			if (len > *max_len_base)
+				*max_len_base = len;
+			if (!is_key_stat(id)) {
+				len = strlen(comp_buf);
+				if (len > *max_len_comp)
+					*max_len_comp = len;
+				len = strlen(diff_buf);
+				if (len > *max_len_diff)
+					*max_len_diff = len;
+			}
+			break;
+		case RESFMT_TABLE: {
+			/* string outputs are left-aligned, number outputs are right-aligned */
+			const char *fmt = base_str ? "%s%-*s" : "%s%*s";
+
+			printf(fmt, i == 0 ? "" : COLUMN_SEP, *max_len_base, base_buf);
+			if (!is_key_stat(id)) {
+				printf(fmt, COLUMN_SEP, *max_len_comp, comp_buf);
+				printf(fmt, COLUMN_SEP, *max_len_diff, diff_buf);
+			}
+			if (i == env.output_spec.spec_cnt - 1)
+				printf("\n");
+			break;
+		}
+		case RESFMT_CSV:
+			printf("%s%s", i == 0 ? "" : ",", base_buf);
+			if (!is_key_stat(id)) {
+				printf("%s%s", i == 0 ? "" : ",", comp_buf);
+				printf("%s%s", i == 0 ? "" : ",", diff_buf);
+			}
+			if (i == env.output_spec.spec_cnt - 1)
+				printf("\n");
+			break;
+		}
+	}
+
+	if (last && fmt == RESFMT_TABLE)
+		output_comp_header_underlines();
+}
+
+static int cmp_stats_key(const struct verif_stats *base, const struct verif_stats *comp)
+{
+	int r;
+
+	r = strcmp(base->file_name, comp->file_name);
+	if (r != 0)
+		return r;
+	return strcmp(base->prog_name, comp->prog_name);
+}
+
+static int handle_comparison_mode(void)
+{
+	struct stat_specs base_specs = {}, comp_specs = {};
+	enum resfmt cur_fmt;
+	int err, i, j;
+
+	if (env.filename_cnt != 2) {
+		fprintf(stderr, "Comparison mode expects exactly two input CSV files!\n");
+		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
+		return -EINVAL;
+	}
+
+	err = parse_stats_csv(env.filenames[0], &base_specs,
+			      &env.baseline_stats, &env.baseline_stat_cnt);
+	if (err) {
+		fprintf(stderr, "Failed to parse stats from '%s': %d\n", env.filenames[0], err);
+		return err;
+	}
+	err = parse_stats_csv(env.filenames[1], &comp_specs,
+			      &env.prog_stats, &env.prog_stat_cnt);
+	if (err) {
+		fprintf(stderr, "Failed to parse stats from '%s': %d\n", env.filenames[1], err);
+		return err;
+	}
+
+	/* To keep it simple we validate that the set and order of stats in
+	 * both CSVs are exactly the same. This can be lifted with a bit more
+	 * pre-processing later.
+	 */
+	if (base_specs.spec_cnt != comp_specs.spec_cnt) {
+		fprintf(stderr, "Number of stats in '%s' and '%s' differs (%d != %d)!\n",
+			env.filenames[0], env.filenames[1],
+			base_specs.spec_cnt, comp_specs.spec_cnt);
+		return -EINVAL;
+	}
+	for (i = 0; i < base_specs.spec_cnt; i++) {
+		if (base_specs.ids[i] != comp_specs.ids[i]) {
+			fprintf(stderr, "Stats composition differs between '%s' and '%s' (%s != %s)!\n",
+				env.filenames[0], env.filenames[1],
+				stat_defs[base_specs.ids[i]].names[0],
+				stat_defs[comp_specs.ids[i]].names[0]);
+			return -EINVAL;
+		}
+	}
+
+	qsort(env.prog_stats, env.prog_stat_cnt, sizeof(*env.prog_stats), cmp_prog_stats);
+	qsort(env.baseline_stats, env.baseline_stat_cnt, sizeof(*env.baseline_stats), cmp_prog_stats);
+
+	/* for human-readable table output we need to do extra pass to
+	 * calculate column widths, so we substitute current output format
+	 * with RESFMT_TABLE_CALCLEN and later revert it back to RESFMT_TABLE
+	 * and do everything again.
+	 */
+	if (env.out_fmt == RESFMT_TABLE)
+		cur_fmt = RESFMT_TABLE_CALCLEN;
+	else
+		cur_fmt = env.out_fmt;
+
+one_more_time:
+	output_comp_headers(cur_fmt);
+
+	/* If baseline and comparison datasets have different subset of rows
+	 * (we match by 'object + prog' as a unique key) then assume
+	 * empty/missing/zero value for rows that are missing in the opposite
+	 * data set
+	 */
+	i = j = 0;
+	while (i < env.baseline_stat_cnt || j < env.prog_stat_cnt) {
+		bool last = (i == env.baseline_stat_cnt - 1) || (j == env.prog_stat_cnt - 1);
+		const struct verif_stats *base, *comp;
+		int r;
+
+		base = i < env.baseline_stat_cnt ? &env.baseline_stats[i] : &fallback_stats;
+		comp = j < env.prog_stat_cnt ? &env.prog_stats[j] : &fallback_stats;
+
+		if (!base->file_name || !base->prog_name) {
+			fprintf(stderr, "Entry #%d in '%s' doesn't have file and/or program name specified!\n",
+				i, env.filenames[0]);
+			return -EINVAL;
+		}
+		if (!comp->file_name || !comp->prog_name) {
+			fprintf(stderr, "Entry #%d in '%s' doesn't have file and/or program name specified!\n",
+				j, env.filenames[1]);
+			return -EINVAL;
+		}
+
+		r = cmp_stats_key(base, comp);
+		if (r == 0) {
+			output_comp_stats(base, comp, cur_fmt, last);
+			i++;
+			j++;
+		} else if (comp == &fallback_stats || r < 0) {
+			output_comp_stats(base, &fallback_stats, cur_fmt, last);
+			i++;
+		} else {
+			output_comp_stats(&fallback_stats, comp, cur_fmt, last);
+			j++;
+		}
+	}
+
+	if (cur_fmt == RESFMT_TABLE_CALCLEN) {
+		cur_fmt = RESFMT_TABLE;
+		goto one_more_time; /* ... this time with feeling */
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int err = 0, i;
+
+	if (argp_parse(&argp, argc, argv, 0, NULL, NULL))
+		return 1;
+
+	if (env.output_spec.spec_cnt == 0)
+		env.output_spec = default_output_spec;
+	if (env.sort_spec.spec_cnt == 0)
+		env.sort_spec = default_sort_spec;
+
+	if (env.comparison_mode)
+		err = handle_comparison_mode();
+	else
+		err = handle_verif_mode();
+
+	free_verif_stats(env.prog_stats, env.prog_stat_cnt);
+	free_verif_stats(env.baseline_stats, env.baseline_stat_cnt);
 	for (i = 0; i < env.filename_cnt; i++)
 		free(env.filenames[i]);
 	free(env.filenames);
+	for (i = 0; i < env.allow_filter_cnt; i++) {
+		free(env.allow_filters[i].file_glob);
+		free(env.allow_filters[i].prog_glob);
+	}
+	free(env.allow_filters);
+	for (i = 0; i < env.deny_filter_cnt; i++) {
+		free(env.deny_filters[i].file_glob);
+		free(env.deny_filters[i].prog_glob);
+	}
+	free(env.deny_filters);
 	return -err;
 }
diff --git a/tools/testing/selftests/bpf/veristat.cfg b/tools/testing/selftests/bpf/veristat.cfg
new file mode 100644
index 000000000000..1a385061618d
--- /dev/null
+++ b/tools/testing/selftests/bpf/veristat.cfg
@@ -0,0 +1,17 @@
+# pre-canned list of rather complex selftests/bpf BPF object files to monitor
+# BPF verifier's performance on
+bpf_flow*
+bpf_loop_bench*
+loop*
+netif_receive_skb*
+profiler*
+pyperf*
+strobemeta*
+test_cls_redirect*
+test_l4lb
+test_sysctl*
+test_tcp_hdr_*
+test_usdt*
+test_verif_scale*
+test_xdp_noinline*
+xdp_synproxy*