Merge branch 'veristat: replay, filtering, sorting'

Andrii Nakryiko says:

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

This patch set adds a bunch of new featurs and improvements that were sorely
missing during recent active use of veristat to develop BPF verifier precision
changes. Individual patches provide justification, explanation and often
examples showing how new capabilities can be used.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/veristat.c

@@ -17,6 +17,7 @@
 #include <bpf/libbpf.h>
 #include <libelf.h>
 #include <gelf.h>
+#include <float.h>
 
 enum stat_id {
 	VERDICT,
@@ -34,6 +35,45 @@ enum stat_id {
 	NUM_STATS_CNT = FILE_NAME - VERDICT,
 };
 
+/* In comparison mode each stat can specify up to four different values:
+ *   - A side value;
+ *   - B side value;
+ *   - absolute diff value;
+ *   - relative (percentage) diff value.
+ *
+ * When specifying stat specs in comparison mode, user can use one of the
+ * following variant suffixes to specify which exact variant should be used for
+ * ordering or filtering:
+ *   - `_a` for A side value;
+ *   - `_b` for B side value;
+ *   - `_diff` for absolute diff value;
+ *   - `_pct` for relative (percentage) diff value.
+ *
+ * If no variant suffix is provided, then `_b` (control data) is assumed.
+ *
+ * As an example, let's say instructions stat has the following output:
+ *
+ * Insns (A)  Insns (B)  Insns   (DIFF)
+ * ---------  ---------  --------------
+ * 21547      20920       -627 (-2.91%)
+ *
+ * Then:
+ *   - 21547 is A side value (insns_a);
+ *   - 20920 is B side value (insns_b);
+ *   - -627 is absolute diff value (insns_diff);
+ *   - -2.91% is relative diff value (insns_pct).
+ *
+ * For verdict there is no verdict_pct variant.
+ * For file and program name, _a and _b variants are equivalent and there are
+ * no _diff or _pct variants.
+ */
+enum stat_variant {
+	VARIANT_A,
+	VARIANT_B,
+	VARIANT_DIFF,
+	VARIANT_PCT,
+};
+
 struct verif_stats {
 	char *file_name;
 	char *prog_name;
@@ -41,9 +81,19 @@ struct verif_stats {
 	long stats[NUM_STATS_CNT];
 };
 
+/* joined comparison mode stats */
+struct verif_stats_join {
+	char *file_name;
+	char *prog_name;
+
+	const struct verif_stats *stats_a;
+	const struct verif_stats *stats_b;
+};
+
 struct stat_specs {
 	int spec_cnt;
 	enum stat_id ids[ALL_STATS_CNT];
+	enum stat_variant variants[ALL_STATS_CNT];
 	bool asc[ALL_STATS_CNT];
 	int lens[ALL_STATS_CNT * 3]; /* 3x for comparison mode */
 };
@@ -54,9 +104,31 @@ enum resfmt {
 	RESFMT_CSV,
 };
 
+enum filter_kind {
+	FILTER_NAME,
+	FILTER_STAT,
+};
+
+enum operator_kind {
+	OP_EQ,		/* == or = */
+	OP_NEQ,		/* != or <> */
+	OP_LT,		/* < */
+	OP_LE,		/* <= */
+	OP_GT,		/* > */
+	OP_GE,		/* >= */
+};
+
 struct filter {
+	enum filter_kind kind;
+	/* FILTER_NAME */
+	char *any_glob;
 	char *file_glob;
 	char *prog_glob;
+	/* FILTER_STAT */
+	enum operator_kind op;
+	int stat_id;
+	enum stat_variant stat_var;
+	long value;
 };
 
 static struct env {
@@ -67,6 +139,7 @@ static struct env {
 	int log_level;
 	enum resfmt out_fmt;
 	bool comparison_mode;
+	bool replay_mode;
 
 	struct verif_stats *prog_stats;
 	int prog_stat_cnt;
@@ -75,6 +148,9 @@ static struct env {
 	struct verif_stats *baseline_stats;
 	int baseline_stat_cnt;
 
+	struct verif_stats_join *join_stats;
+	int join_stat_cnt;
+
 	struct stat_specs output_spec;
 	struct stat_specs sort_spec;
 
@@ -115,6 +191,7 @@ static const struct argp_option opts[] = {
 	{ "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" },
+	{ "replay", 'R', NULL, 0, "Replay mode" },
 	{ "filter", 'f', "FILTER", 0, "Filter expressions (or @filename for file with expressions)." },
 	{},
 };
@@ -169,6 +246,9 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	case 'C':
 		env.comparison_mode = true;
 		break;
+	case 'R':
+		env.replay_mode = true;
+		break;
 	case 'f':
 		if (arg[0] == '@')
 			err = append_filter_file(arg + 1);
@@ -226,28 +306,6 @@ static bool glob_matches(const char *str, const char *pat)
 	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 is_bpf_obj_file(const char *path) {
 	Elf64_Ehdr *ehdr;
 	int fd, err = -EINVAL;
@@ -280,45 +338,78 @@ static bool is_bpf_obj_file(const char *path) {
 	return err == 0;
 }
 
-static bool should_process_prog(const char *path, const char *prog_name)
+static bool should_process_file_prog(const char *filename, const char *prog_name)
 {
-	const char *filename = basename(path);
-	int i;
+	struct filter *f;
+	int i, allow_cnt = 0;
 
-	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;
-		}
-	}
+	for (i = 0; i < env.deny_filter_cnt; i++) {
+		f = &env.deny_filters[i];
+		if (f->kind != FILTER_NAME)
+			continue;
 
-	if (env.allow_filter_cnt == 0)
-		return true;
+		if (f->any_glob && glob_matches(filename, f->any_glob))
+			return false;
+		if (f->any_glob && prog_name && glob_matches(prog_name, f->any_glob))
+			return false;
+		if (f->file_glob && glob_matches(filename, f->file_glob))
+			return false;
+		if (f->prog_glob && prog_name && glob_matches(prog_name, f->prog_glob))
+			return false;
+	}
 
 	for (i = 0; i < env.allow_filter_cnt; i++) {
-		if (!glob_matches(filename, env.allow_filters[i].file_glob))
+		f = &env.allow_filters[i];
+		if (f->kind != FILTER_NAME)
 			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))
+
+		allow_cnt++;
+		if (f->any_glob) {
+			if (glob_matches(filename, f->any_glob))
+				return true;
+			if (prog_name && glob_matches(prog_name, f->any_glob))
+				return true;
+		} else {
+			if (f->file_glob && !glob_matches(filename, f->file_glob))
+				continue;
+			if (f->prog_glob && prog_name && !glob_matches(prog_name, f->prog_glob))
+				continue;
 			return true;
+		}
 	}
 
-	return false;
+	/* if there are no file/prog name allow filters, allow all progs,
+	 * unless they are denied earlier explicitly
+	 */
+	return allow_cnt == 0;
 }
 
+static struct {
+	enum operator_kind op_kind;
+	const char *op_str;
+} operators[] = {
+	/* Order of these definitions matter to avoid situations like '<'
+	 * matching part of what is actually a '<>' operator. That is,
+	 * substrings should go last.
+	 */
+	{ OP_EQ, "==" },
+	{ OP_NEQ, "!=" },
+	{ OP_NEQ, "<>" },
+	{ OP_LE, "<=" },
+	{ OP_LT, "<" },
+	{ OP_GE, ">=" },
+	{ OP_GT, ">" },
+	{ OP_EQ, "=" },
+};
+
+static bool parse_stat_id_var(const char *name, size_t len, int *id, enum stat_variant *var);
+
 static int append_filter(struct filter **filters, int *cnt, const char *str)
 {
 	struct filter *f;
 	void *tmp;
 	const char *p;
+	int i;
 
 	tmp = realloc(*filters, (*cnt + 1) * sizeof(**filters));
 	if (!tmp)
@@ -326,26 +417,108 @@ static int append_filter(struct filter **filters, int *cnt, const char *str)
 	*filters = tmp;
 
 	f = &(*filters)[*cnt];
-	f->file_glob = f->prog_glob = NULL;
+	memset(f, 0, sizeof(*f));
+
+	/* First, let's check if it's a stats filter of the following form:
+	 * <stat><op><value, where:
+	 *   - <stat> is one of supported numerical stats (verdict is also
+	 *     considered numerical, failure == 0, success == 1);
+	 *   - <op> is comparison operator (see `operators` definitions);
+	 *   - <value> is an integer (or failure/success, or false/true as
+	 *     special aliases for 0 and 1, respectively).
+	 * If the form doesn't match what user provided, we assume file/prog
+	 * glob filter.
+	 */
+	for (i = 0; i < ARRAY_SIZE(operators); i++) {
+		enum stat_variant var;
+		int id;
+		long val;
+		const char *end = str;
+		const char *op_str;
 
-	/* filter can be specified either as "<obj-glob>" or "<obj-glob>/<prog-glob>" */
+		op_str = operators[i].op_str;
+		p = strstr(str, op_str);
+		if (!p)
+			continue;
+
+		if (!parse_stat_id_var(str, p - str, &id, &var)) {
+			fprintf(stderr, "Unrecognized stat name in '%s'!\n", str);
+			return -EINVAL;
+		}
+		if (id >= FILE_NAME) {
+			fprintf(stderr, "Non-integer stat is specified in '%s'!\n", str);
+			return -EINVAL;
+		}
+
+		p += strlen(op_str);
+
+		if (strcasecmp(p, "true") == 0 ||
+		    strcasecmp(p, "t") == 0 ||
+		    strcasecmp(p, "success") == 0 ||
+		    strcasecmp(p, "succ") == 0 ||
+		    strcasecmp(p, "s") == 0 ||
+		    strcasecmp(p, "match") == 0 ||
+		    strcasecmp(p, "m") == 0) {
+			val = 1;
+		} else if (strcasecmp(p, "false") == 0 ||
+			   strcasecmp(p, "f") == 0 ||
+			   strcasecmp(p, "failure") == 0 ||
+			   strcasecmp(p, "fail") == 0 ||
+			   strcasecmp(p, "mismatch") == 0 ||
+			   strcasecmp(p, "mis") == 0) {
+			val = 0;
+		} else {
+			errno = 0;
+			val = strtol(p, (char **)&end, 10);
+			if (errno || end == p || *end != '\0' ) {
+				fprintf(stderr, "Invalid integer value in '%s'!\n", str);
+				return -EINVAL;
+			}
+		}
+
+		f->kind = FILTER_STAT;
+		f->stat_id = id;
+		f->stat_var = var;
+		f->op = operators[i].op_kind;
+		f->value = val;
+
+		*cnt += 1;
+		return 0;
+	}
+
+	/* File/prog filter can be specified either as '<glob>' or
+	 * '<file-glob>/<prog-glob>'. In the former case <glob> is applied to
+	 * both file and program names. This seems to be way more useful in
+	 * practice. If user needs full control, they can use '/<prog-glob>'
+	 * form to glob just program name, or '<file-glob>/' to glob only file
+	 * name. But usually common <glob> seems to be the most useful and
+	 * ergonomic way.
+	 */
+	f->kind = FILTER_NAME;
 	p = strchr(str, '/');
 	if (!p) {
-		f->file_glob = strdup(str);
-		if (!f->file_glob)
+		f->any_glob = strdup(str);
+		if (!f->any_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;
+		if (str != p) {
+			/* non-empty file glob */
+			f->file_glob = strndup(str, p - str);
+			if (!f->file_glob)
+				return -ENOMEM;
+		}
+		if (strlen(p + 1) > 0) {
+			/* non-empty prog glob */
+			f->prog_glob = strdup(p + 1);
+			if (!f->prog_glob) {
+				free(f->file_glob);
+				f->file_glob = NULL;
+				return -ENOMEM;
+			}
 		}
 	}
 
-	*cnt = *cnt + 1;
+	*cnt += 1;
 	return 0;
 }
 
@@ -388,6 +561,15 @@ static const struct stat_specs default_output_spec = {
 	},
 };
 
+static const struct stat_specs default_csv_output_spec = {
+	.spec_cnt = 9,
+	.ids = {
+		FILE_NAME, PROG_NAME, VERDICT, DURATION,
+		TOTAL_INSNS, TOTAL_STATES, PEAK_STATES,
+		MAX_STATES_PER_INSN, MARK_READ_MAX_LEN,
+	},
+};
+
 static const struct stat_specs default_sort_spec = {
 	.spec_cnt = 2,
 	.ids = {
@@ -396,48 +578,123 @@ static const struct stat_specs default_sort_spec = {
 	.asc = { true, true, },
 };
 
+/* sorting for comparison mode to join two data sets */
+static const struct stat_specs join_sort_spec = {
+	.spec_cnt = 2,
+	.ids = {
+		FILE_NAME, PROG_NAME,
+	},
+	.asc = { true, true, },
+};
+
 static struct stat_def {
 	const char *header;
 	const char *names[4];
 	bool asc_by_default;
+	bool left_aligned;
 } stat_defs[] = {
-	[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 */ },
+	[FILE_NAME] = { "File", {"file_name", "filename", "file"}, true /* asc */, true /* left */ },
+	[PROG_NAME] = { "Program", {"prog_name", "progname", "prog"}, true /* asc */, true /* left */ },
+	[VERDICT] = { "Verdict", {"verdict"}, true /* asc: failure, success */, true /* left */ },
 	[DURATION] = { "Duration (us)", {"duration", "dur"}, },
-	[TOTAL_INSNS] = { "Total insns", {"total_insns", "insns"}, },
-	[TOTAL_STATES] = { "Total states", {"total_states", "states"}, },
+	[TOTAL_INSNS] = { "Insns", {"total_insns", "insns"}, },
+	[TOTAL_STATES] = { "States", {"total_states", "states"}, },
 	[PEAK_STATES] = { "Peak states", {"peak_states"}, },
 	[MAX_STATES_PER_INSN] = { "Max states per insn", {"max_states_per_insn"}, },
 	[MARK_READ_MAX_LEN] = { "Max mark read length", {"max_mark_read_len", "mark_read"}, },
 };
 
+static bool parse_stat_id_var(const char *name, size_t len, int *id, enum stat_variant *var)
+{
+	static const char *var_sfxs[] = {
+		[VARIANT_A] = "_a",
+		[VARIANT_B] = "_b",
+		[VARIANT_DIFF] = "_diff",
+		[VARIANT_PCT] = "_pct",
+	};
+	int i, j, k;
+
+	for (i = 0; i < ARRAY_SIZE(stat_defs); i++) {
+		struct stat_def *def = &stat_defs[i];
+		size_t alias_len, sfx_len;
+		const char *alias;
+
+		for (j = 0; j < ARRAY_SIZE(stat_defs[i].names); j++) {
+			alias = def->names[j];
+			if (!alias)
+				continue;
+
+			alias_len = strlen(alias);
+			if (strncmp(name, alias, alias_len) != 0)
+				continue;
+
+			if (alias_len == len) {
+				/* If no variant suffix is specified, we
+				 * assume control group (just in case we are
+				 * in comparison mode. Variant is ignored in
+				 * non-comparison mode.
+				 */
+				*var = VARIANT_B;
+				*id = i;
+				return true;
+			}
+
+			for (k = 0; k < ARRAY_SIZE(var_sfxs); k++) {
+				sfx_len = strlen(var_sfxs[k]);
+				if (alias_len + sfx_len != len)
+					continue;
+
+				if (strncmp(name + alias_len, var_sfxs[k], sfx_len) == 0) {
+					*var = (enum stat_variant)k;
+					*id = i;
+					return true;
+				}
+			}
+		}
+	}
+
+	return false;
+}
+
+static bool is_asc_sym(char c)
+{
+	return c == '^';
+}
+
+static bool is_desc_sym(char c)
+{
+	return c == 'v' || c == 'V' || c == '.' || c == '!' || c == '_';
+}
+
 static int parse_stat(const char *stat_name, struct stat_specs *specs)
 {
-	int id, i;
+	int id;
+	bool has_order = false, is_asc = false;
+	size_t len = strlen(stat_name);
+	enum stat_variant var;
 
 	if (specs->spec_cnt >= ARRAY_SIZE(specs->ids)) {
 		fprintf(stderr, "Can't specify more than %zd stats\n", ARRAY_SIZE(specs->ids));
 		return -E2BIG;
 	}
 
-	for (id = 0; id < ARRAY_SIZE(stat_defs); id++) {
-		struct stat_def *def = &stat_defs[id];
-
-		for (i = 0; i < ARRAY_SIZE(stat_defs[id].names); i++) {
-			if (!def->names[i] || strcmp(def->names[i], stat_name) != 0)
-				continue;
-
-			specs->ids[specs->spec_cnt] = id;
-			specs->asc[specs->spec_cnt] = def->asc_by_default;
-			specs->spec_cnt++;
+	if (len > 1 && (is_asc_sym(stat_name[len - 1]) || is_desc_sym(stat_name[len - 1]))) {
+		has_order = true;
+		is_asc = is_asc_sym(stat_name[len - 1]);
+		len -= 1;
+	}
 
-			return 0;
-		}
+	if (!parse_stat_id_var(stat_name, len, &id, &var)) {
+		fprintf(stderr, "Unrecognized stat name '%s'\n", stat_name);
+		return -ESRCH;
 	}
 
-	fprintf(stderr, "Unrecognized stat name '%s'\n", stat_name);
-	return -ESRCH;
+	specs->ids[specs->spec_cnt] = id;
+	specs->variants[specs->spec_cnt] = var;
+	specs->asc[specs->spec_cnt] = has_order ? is_asc : stat_defs[id].asc_by_default;
+	specs->spec_cnt++;
+
+	return 0;
 }
 
 static int parse_stats(const char *stats_str, struct stat_specs *specs)
@@ -540,7 +797,7 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
 	int err = 0;
 	void *tmp;
 
-	if (!should_process_prog(filename, bpf_program__name(prog))) {
+	if (!should_process_file_prog(basename(filename), bpf_program__name(prog))) {
 		env.progs_skipped++;
 		return 0;
 	}
@@ -596,7 +853,7 @@ 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))) {
+	if (!should_process_file_prog(basename(filename), NULL)) {
 		if (env.verbose)
 			printf("Skipping '%s' due to filters...\n", filename);
 		env.files_skipped++;
@@ -716,7 +973,106 @@ static int cmp_prog_stats(const void *v1, const void *v2)
 			return cmp;
 	}
 
-	return 0;
+	/* always disambiguate with file+prog, which are unique */
+	cmp = strcmp(s1->file_name, s2->file_name);
+	if (cmp != 0)
+		return cmp;
+	return strcmp(s1->prog_name, s2->prog_name);
+}
+
+static void fetch_join_stat_value(const struct verif_stats_join *s,
+				  enum stat_id id, enum stat_variant var,
+				  const char **str_val,
+				  double *num_val)
+{
+	long v1, v2;
+
+	if (id == FILE_NAME) {
+		*str_val = s->file_name;
+		return;
+	}
+	if (id == PROG_NAME) {
+		*str_val = s->prog_name;
+		return;
+	}
+
+	v1 = s->stats_a ? s->stats_a->stats[id] : 0;
+	v2 = s->stats_b ? s->stats_b->stats[id] : 0;
+
+	switch (var) {
+	case VARIANT_A:
+		if (!s->stats_a)
+			*num_val = -DBL_MAX;
+		else
+			*num_val = s->stats_a->stats[id];
+		return;
+	case VARIANT_B:
+		if (!s->stats_b)
+			*num_val = -DBL_MAX;
+		else
+			*num_val = s->stats_b->stats[id];
+		return;
+	case VARIANT_DIFF:
+		if (!s->stats_a || !s->stats_b)
+			*num_val = -DBL_MAX;
+		else if (id == VERDICT)
+			*num_val = v1 == v2 ? 1.0 /* MATCH */ : 0.0 /* MISMATCH */;
+		else
+			*num_val = (double)(v2 - v1);
+		return;
+	case VARIANT_PCT:
+		if (!s->stats_a || !s->stats_b) {
+			*num_val = -DBL_MAX;
+		} else if (v1 == 0) {
+			if (v1 == v2)
+				*num_val = 0.0;
+			else
+				*num_val = v2 < v1 ? -100.0 : 100.0;
+		} else {
+			 *num_val = (v2 - v1) * 100.0 / v1;
+		}
+		return;
+	}
+}
+
+static int cmp_join_stat(const struct verif_stats_join *s1,
+			 const struct verif_stats_join *s2,
+			 enum stat_id id, enum stat_variant var, bool asc)
+{
+	const char *str1 = NULL, *str2 = NULL;
+	double v1, v2;
+	int cmp = 0;
+
+	fetch_join_stat_value(s1, id, var, &str1, &v1);
+	fetch_join_stat_value(s2, id, var, &str2, &v2);
+
+	if (str1)
+		cmp = strcmp(str1, str2);
+	else if (v1 != v2)
+		cmp = v1 < v2 ? -1 : 1;
+
+	return asc ? cmp : -cmp;
+}
+
+static int cmp_join_stats(const void *v1, const void *v2)
+{
+	const struct verif_stats_join *s1 = v1, *s2 = v2;
+	int i, cmp;
+
+	for (i = 0; i < env.sort_spec.spec_cnt; i++) {
+		cmp = cmp_join_stat(s1, s2,
+				    env.sort_spec.ids[i],
+				    env.sort_spec.variants[i],
+				    env.sort_spec.asc[i]);
+		if (cmp != 0)
+			return cmp;
+	}
+
+	/* always disambiguate with file+prog, which are unique */
+	cmp = strcmp(s1->file_name, s2->file_name);
+	if (cmp != 0)
+		return cmp;
+	return strcmp(s1->prog_name, s2->prog_name);
 }
 
 #define HEADER_CHAR '-'
@@ -738,6 +1094,7 @@ static void output_header_underlines(void)
 
 static void output_headers(enum resfmt fmt)
 {
+	const char *fmt_str;
 	int i, len;
 
 	for (i = 0; i < env.output_spec.spec_cnt; i++) {
@@ -751,7 +1108,8 @@ static void output_headers(enum resfmt fmt)
 				*max_len = len;
 			break;
 		case RESFMT_TABLE:
-			printf("%s%-*s", i == 0 ? "" : COLUMN_SEP,  *max_len, stat_defs[id].header);
+			fmt_str = stat_defs[id].left_aligned ? "%s%-*s" : "%s%*s";
+			printf(fmt_str, i == 0 ? "" : COLUMN_SEP,  *max_len, stat_defs[id].header);
 			if (i == env.output_spec.spec_cnt - 1)
 				printf("\n");
 			break;
@@ -772,13 +1130,16 @@ static void prepare_value(const struct verif_stats *s, enum stat_id id,
 {
 	switch (id) {
 	case FILE_NAME:
-		*str = s->file_name;
+		*str = s ? s->file_name : "N/A";
 		break;
 	case PROG_NAME:
-		*str = s->prog_name;
+		*str = s ? s->prog_name : "N/A";
 		break;
 	case VERDICT:
-		*str = s->stats[VERDICT] ? "success" : "failure";
+		if (!s)
+			*str = "N/A";
+		else
+			*str = s->stats[VERDICT] ? "success" : "failure";
 		break;
 	case DURATION:
 	case TOTAL_INSNS:
@@ -786,7 +1147,7 @@ static void prepare_value(const struct verif_stats *s, enum stat_id id,
 	case PEAK_STATES:
 	case MAX_STATES_PER_INSN:
 	case MARK_READ_MAX_LEN:
-		*val = s->stats[id];
+		*val = s ? s->stats[id] : 0;
 		break;
 	default:
 		fprintf(stderr, "Unrecognized stat #%d\n", id);
@@ -841,42 +1202,6 @@ static void output_stats(const struct verif_stats *s, enum resfmt fmt, bool last
 	}
 }
 
-static int handle_verif_mode(void)
-{
-	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 -EINVAL;
-	}
-
-	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);
-			return err;
-		}
-	}
-
-	qsort(env.prog_stats, env.prog_stat_cnt, sizeof(*env.prog_stats), cmp_prog_stats);
-
-	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(env.out_fmt);
-	for (i = 0; i < env.prog_stat_cnt; i++) {
-		output_stats(&env.prog_stats[i], env.out_fmt, i == env.prog_stat_cnt - 1);
-	}
-
-	return 0;
-}
-
 static int parse_stat_value(const char *str, enum stat_id id, struct verif_stats *st)
 {
 	switch (id) {
@@ -1008,7 +1333,7 @@ static int parse_stats_csv(const char *filename, struct stat_specs *specs,
 		 * parsed entire line; if row should be ignored we pretend we
 		 * never parsed it
 		 */
-		if (!should_process_prog(st->file_name, st->prog_name)) {
+		if (!should_process_file_prog(st->file_name, st->prog_name)) {
 			free(st->file_name);
 			free(st->prog_name);
 			*stat_cntp -= 1;
@@ -1097,9 +1422,11 @@ static void output_comp_headers(enum resfmt fmt)
 		output_comp_header_underlines();
 }
 
-static void output_comp_stats(const struct verif_stats *base, const struct verif_stats *comp,
+static void output_comp_stats(const struct verif_stats_join *join_stats,
 			      enum resfmt fmt, bool last)
 {
+	const struct verif_stats *base = join_stats->stats_a;
+	const struct verif_stats *comp = join_stats->stats_b;
 	char base_buf[1024] = {}, comp_buf[1024] = {}, diff_buf[1024] = {};
 	int i;
 
@@ -1117,33 +1444,45 @@ static void output_comp_stats(const struct verif_stats *base, const struct verif
 		/* 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)
+			if (base)
 				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)
+			if (!base || !comp)
+				snprintf(diff_buf, sizeof(diff_buf), "%s", "N/A");
+			else 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 {
 			double p = 0.0;
 
-			snprintf(base_buf, sizeof(base_buf), "%ld", base_val);
-			snprintf(comp_buf, sizeof(comp_buf), "%ld", comp_val);
+			if (base)
+				snprintf(base_buf, sizeof(base_buf), "%ld", base_val);
+			else
+				snprintf(base_buf, sizeof(base_buf), "%s", "N/A");
+			if (comp)
+				snprintf(comp_buf, sizeof(comp_buf), "%ld", comp_val);
+			else
+				snprintf(comp_buf, sizeof(comp_buf), "%s", "N/A");
 
 			diff_val = comp_val - base_val;
-			if (base == &fallback_stats || comp == &fallback_stats || base_val == 0) {
-				if (comp_val == base_val)
-					p = 0.0; /* avoid +0 (+100%) case */
-				else
-					p = comp_val < base_val ? -100.0 : 100.0;
+			if (!base || !comp) {
+				snprintf(diff_buf, sizeof(diff_buf), "%s", "N/A");
 			} else {
-				 p = diff_val * 100.0 / base_val;
+				if (base_val == 0) {
+					if (comp_val == base_val)
+						p = 0.0; /* avoid +0 (+100%) case */
+					else
+						p = comp_val < base_val ? -100.0 : 100.0;
+				} else {
+					 p = diff_val * 100.0 / base_val;
+				}
+				snprintf(diff_buf, sizeof(diff_buf), "%+ld (%+.2lf%%)", diff_val, p);
 			}
-			snprintf(diff_buf, sizeof(diff_buf), "%+ld (%+.2lf%%)", diff_val, p);
 		}
 
 		switch (fmt) {
@@ -1199,14 +1538,64 @@ static int cmp_stats_key(const struct verif_stats *base, const struct verif_stat
 	return strcmp(base->prog_name, comp->prog_name);
 }
 
+static bool is_join_stat_filter_matched(struct filter *f, const struct verif_stats_join *stats)
+{
+	static const double eps = 1e-9;
+	const char *str = NULL;
+	double value = 0.0;
+
+	fetch_join_stat_value(stats, f->stat_id, f->stat_var, &str, &value);
+
+	switch (f->op) {
+	case OP_EQ: return value > f->value - eps && value < f->value + eps;
+	case OP_NEQ: return value < f->value - eps || value > f->value + eps;
+	case OP_LT: return value < f->value - eps;
+	case OP_LE: return value <= f->value + eps;
+	case OP_GT: return value > f->value + eps;
+	case OP_GE: return value >= f->value - eps;
+	}
+
+	fprintf(stderr, "BUG: unknown filter op %d!\n", f->op);
+	return false;
+}
+
+static bool should_output_join_stats(const struct verif_stats_join *stats)
+{
+	struct filter *f;
+	int i, allow_cnt = 0;
+
+	for (i = 0; i < env.deny_filter_cnt; i++) {
+		f = &env.deny_filters[i];
+		if (f->kind != FILTER_STAT)
+			continue;
+
+		if (is_join_stat_filter_matched(f, stats))
+			return false;
+	}
+
+	for (i = 0; i < env.allow_filter_cnt; i++) {
+		f = &env.allow_filters[i];
+		if (f->kind != FILTER_STAT)
+			continue;
+		allow_cnt++;
+
+		if (is_join_stat_filter_matched(f, stats))
+			return true;
+	}
+
+	/* if there are no stat allowed filters, pass everything through */
+	return allow_cnt == 0;
+}
+
 static int handle_comparison_mode(void)
 {
 	struct stat_specs base_specs = {}, comp_specs = {};
+	struct stat_specs tmp_sort_spec;
 	enum resfmt cur_fmt;
-	int err, i, j;
+	int err, i, j, last_idx;
 
 	if (env.filename_cnt != 2) {
-		fprintf(stderr, "Comparison mode expects exactly two input CSV files!\n");
+		fprintf(stderr, "Comparison mode expects exactly two input CSV files!\n\n");
 		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
 		return -EINVAL;
 	}
@@ -1244,31 +1633,26 @@ static int handle_comparison_mode(void)
 		}
 	}
 
+	/* Replace user-specified sorting spec with file+prog sorting rule to
+	 * be able to join two datasets correctly. Once we are done, we will
+	 * restore the original sort spec.
+	 */
+	tmp_sort_spec = env.sort_spec;
+	env.sort_spec = join_sort_spec;
 	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);
+	env.sort_spec = tmp_sort_spec;
 
-	/* 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
+	/* Join two datasets together. 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;
+		struct verif_stats_join *join;
+		void *tmp;
 		int r;
 
 		base = i < env.baseline_stat_cnt ? &env.baseline_stats[i] : &fallback_stats;
@@ -1285,18 +1669,64 @@ static int handle_comparison_mode(void)
 			return -EINVAL;
 		}
 
+		tmp = realloc(env.join_stats, (env.join_stat_cnt + 1) * sizeof(*env.join_stats));
+		if (!tmp)
+			return -ENOMEM;
+		env.join_stats = tmp;
+
+		join = &env.join_stats[env.join_stat_cnt];
+		memset(join, 0, sizeof(*join));
+
 		r = cmp_stats_key(base, comp);
 		if (r == 0) {
-			output_comp_stats(base, comp, cur_fmt, last);
+			join->file_name = base->file_name;
+			join->prog_name = base->prog_name;
+			join->stats_a = base;
+			join->stats_b = comp;
 			i++;
 			j++;
 		} else if (comp == &fallback_stats || r < 0) {
-			output_comp_stats(base, &fallback_stats, cur_fmt, last);
+			join->file_name = base->file_name;
+			join->prog_name = base->prog_name;
+			join->stats_a = base;
+			join->stats_b = NULL;
 			i++;
 		} else {
-			output_comp_stats(&fallback_stats, comp, cur_fmt, last);
+			join->file_name = comp->file_name;
+			join->prog_name = comp->prog_name;
+			join->stats_a = NULL;
+			join->stats_b = comp;
 			j++;
 		}
+		env.join_stat_cnt += 1;
+	}
+
+	/* now sort joined results accorsing to sort spec */
+	qsort(env.join_stats, env.join_stat_cnt, sizeof(*env.join_stats), cmp_join_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);
+
+	for (i = 0; i < env.join_stat_cnt; i++) {
+		const struct verif_stats_join *join = &env.join_stats[i];
+
+		if (!should_output_join_stats(join))
+			continue;
+
+		if (cur_fmt == RESFMT_TABLE_CALCLEN)
+			last_idx = i;
+
+		output_comp_stats(join, cur_fmt, i == last_idx);
 	}
 
 	if (cur_fmt == RESFMT_TABLE_CALCLEN) {
@@ -1307,6 +1737,128 @@ static int handle_comparison_mode(void)
 	return 0;
 }
 
+static bool is_stat_filter_matched(struct filter *f, const struct verif_stats *stats)
+{
+	long value = stats->stats[f->stat_id];
+
+	switch (f->op) {
+	case OP_EQ: return value == f->value;
+	case OP_NEQ: return value != f->value;
+	case OP_LT: return value < f->value;
+	case OP_LE: return value <= f->value;
+	case OP_GT: return value > f->value;
+	case OP_GE: return value >= f->value;
+	}
+
+	fprintf(stderr, "BUG: unknown filter op %d!\n", f->op);
+	return false;
+}
+
+static bool should_output_stats(const struct verif_stats *stats)
+{
+	struct filter *f;
+	int i, allow_cnt = 0;
+
+	for (i = 0; i < env.deny_filter_cnt; i++) {
+		f = &env.deny_filters[i];
+		if (f->kind != FILTER_STAT)
+			continue;
+
+		if (is_stat_filter_matched(f, stats))
+			return false;
+	}
+
+	for (i = 0; i < env.allow_filter_cnt; i++) {
+		f = &env.allow_filters[i];
+		if (f->kind != FILTER_STAT)
+			continue;
+		allow_cnt++;
+
+		if (is_stat_filter_matched(f, stats))
+			return true;
+	}
+
+	/* if there are no stat allowed filters, pass everything through */
+	return allow_cnt == 0;
+}
+
+static void output_prog_stats(void)
+{
+	const struct verif_stats *stats;
+	int i, last_stat_idx = 0;
+
+	if (env.out_fmt == RESFMT_TABLE) {
+		/* calculate column widths */
+		output_headers(RESFMT_TABLE_CALCLEN);
+		for (i = 0; i < env.prog_stat_cnt; i++) {
+			stats = &env.prog_stats[i];
+			if (!should_output_stats(stats))
+				continue;
+			output_stats(stats, RESFMT_TABLE_CALCLEN, false);
+			last_stat_idx = i;
+		}
+	}
+
+	/* actually output the table */
+	output_headers(env.out_fmt);
+	for (i = 0; i < env.prog_stat_cnt; i++) {
+		stats = &env.prog_stats[i];
+		if (!should_output_stats(stats))
+			continue;
+		output_stats(stats, env.out_fmt, i == last_stat_idx);
+	}
+}
+
+static int handle_verif_mode(void)
+{
+	int i, err;
+
+	if (env.filename_cnt == 0) {
+		fprintf(stderr, "Please provide path to BPF object file!\n\n");
+		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
+		return -EINVAL;
+	}
+
+	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);
+			return err;
+		}
+	}
+
+	qsort(env.prog_stats, env.prog_stat_cnt, sizeof(*env.prog_stats), cmp_prog_stats);
+
+	output_prog_stats();
+
+	return 0;
+}
+
+static int handle_replay_mode(void)
+{
+	struct stat_specs specs = {};
+	int err;
+
+	if (env.filename_cnt != 1) {
+		fprintf(stderr, "Replay mode expects exactly one input CSV file!\n\n");
+		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
+		return -EINVAL;
+	}
+
+	err = parse_stats_csv(env.filenames[0], &specs,
+			      &env.prog_stats, &env.prog_stat_cnt);
+	if (err) {
+		fprintf(stderr, "Failed to parse stats from '%s': %d\n", env.filenames[0], err);
+		return err;
+	}
+
+	qsort(env.prog_stats, env.prog_stat_cnt, sizeof(*env.prog_stats), cmp_prog_stats);
+
+	output_prog_stats();
+
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	int err = 0, i;
@@ -1315,34 +1867,49 @@ int main(int argc, char **argv)
 		return 1;
 
 	if (env.verbose && env.quiet) {
-		fprintf(stderr, "Verbose and quiet modes are incompatible, please specify just one or neither!\n");
+		fprintf(stderr, "Verbose and quiet modes are incompatible, please specify just one or neither!\n\n");
 		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
 		return 1;
 	}
 	if (env.verbose && env.log_level == 0)
 		env.log_level = 1;
 
-	if (env.output_spec.spec_cnt == 0)
-		env.output_spec = default_output_spec;
+	if (env.output_spec.spec_cnt == 0) {
+		if (env.out_fmt == RESFMT_CSV)
+			env.output_spec = default_csv_output_spec;
+		else
+			env.output_spec = default_output_spec;
+	}
 	if (env.sort_spec.spec_cnt == 0)
 		env.sort_spec = default_sort_spec;
 
+	if (env.comparison_mode && env.replay_mode) {
+		fprintf(stderr, "Can't specify replay and comparison mode at the same time!\n\n");
+		argp_help(&argp, stderr, ARGP_HELP_USAGE, "veristat");
+		return 1;
+	}
+
 	if (env.comparison_mode)
 		err = handle_comparison_mode();
+	else if (env.replay_mode)
+		err = handle_replay_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);
+	free(env.join_stats);
 	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].any_glob);
 		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].any_glob);
 		free(env.deny_filters[i].file_glob);
 		free(env.deny_filters[i].prog_glob);
 	}