[PATCH bpf-next v5 0/3] Support array presets in veristat

[PATCH bpf-next v5 0/3] Support array presets in veristat

[Mykyta Yatsenko]

From: Mykyta Yatsenko <yatsenko@meta.com>

This patch series implements support for array variable presets in
veristat. Currently users can set values to global variables before
loading BPF program, but not for arrays. With this change array
elements are supported as well, for example:
```
sudo ./veristat set_global_vars.bpf.o -G "arr[0] = 1"
```

v4 -> v5
 * Simplify array elements offset calculation using  btf__resolve_size
 * Support white spaces in array indexes, e.g. arr [ 0 ]
 * Rename btf_find_member into adjust_var_secinfo_member

v3 -> v4
 * Rework implementation to support multi dimensional arrays
 * Rework data structures for storing parsed presets

v2 -> v3
 * Added more negative tests
 * Fix mem leak
 * Other small fixes

v1 -> v2
 * Support enums as indexes
 * Separating parsing logic from preset processing
 * Add more tests

Mykyta Yatsenko (3):
  selftests/bpf: separate var preset parsing in veristat
  selftests/bpf: support array presets in veristat
  selftests/bpf: test array presets in veristat

 .../selftests/bpf/prog_tests/test_veristat.c  | 127 ++++++-
 .../selftests/bpf/progs/set_global_vars.c     |  56 ++-
 tools/testing/selftests/bpf/veristat.c        | 343 ++++++++++++++----
 3 files changed, 423 insertions(+), 103 deletions(-)

-- 
2.50.0

[PATCH bpf-next v5 1/3] selftests/bpf: separate var preset parsing in veristat

[Mykyta Yatsenko]

From: Mykyta Yatsenko <yatsenko@meta.com>

Refactor var preset parsing in veristat to simplify implementation.
Prepare parsed variable beforehand so that parsing logic is separated
from functionality of calculating offsets and searching fields.
Introduce rvalue struct, storing either int or enum (string value),
will be reused in the next patch, extract parsing rvalue into a
separate function.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
 tools/testing/selftests/bpf/veristat.c | 152 ++++++++++++++++---------
 1 file changed, 99 insertions(+), 53 deletions(-)

diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
index 56771650ee8c..483442c08ecf 100644
--- a/tools/testing/selftests/bpf/veristat.c
+++ b/tools/testing/selftests/bpf/veristat.c
@@ -156,13 +156,23 @@ struct filter {
 	bool abs;
 };
 
-struct var_preset {
-	char *name;
+struct rvalue {
 	enum { INTEGRAL, ENUMERATOR } type;
 	union {
 		long long ivalue;
 		char *svalue;
 	};
+};
+
+struct field_access {
+	char *name;
+};
+
+struct var_preset {
+	struct field_access *atoms;
+	int atom_count;
+	char *full_name;
+	struct rvalue value;
 	bool applied;
 };
 
@@ -1497,6 +1507,35 @@ static int reset_stat_cgroup(void)
 	return 0;
 }
 
+static int parse_rvalue(const char *val, struct rvalue *rvalue)
+{
+	long long value;
+	char *val_end;
+
+	if (val[0] == '-' || isdigit(val[0])) {
+		/* must be a number */
+		errno = 0;
+		value = strtoll(val, &val_end, 0);
+		if (errno == ERANGE) {
+			errno = 0;
+			value = strtoull(val, &val_end, 0);
+		}
+		if (errno || *val_end != '\0') {
+			fprintf(stderr, "Failed to parse value '%s'\n", val);
+			return -EINVAL;
+		}
+		rvalue->ivalue = value;
+		rvalue->type = INTEGRAL;
+	} else {
+		/* if not a number, consider it enum value */
+		rvalue->svalue = strdup(val);
+		if (!rvalue->svalue)
+			return -ENOMEM;
+		rvalue->type = ENUMERATOR;
+	}
+	return 0;
+}
+
 static int process_prog(const char *filename, struct bpf_object *obj, struct bpf_program *prog)
 {
 	const char *base_filename = basename(strdupa(filename));
@@ -1592,13 +1631,36 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
 	return 0;
 };
 
+static int parse_var_atoms(const char *full_var, struct var_preset *preset)
+{
+	char expr[256], *name, *saveptr;
+
+	snprintf(expr, sizeof(expr), "%s", full_var);
+	preset->atom_count = 0;
+	while ((name = strtok_r(preset->atom_count ? NULL : expr, ".", &saveptr))) {
+		struct field_access *tmp;
+		int i = preset->atom_count;
+
+		tmp = reallocarray(preset->atoms, i + 1, sizeof(*preset->atoms));
+		if (!tmp)
+			return -ENOMEM;
+
+		preset->atoms = tmp;
+		preset->atom_count++;
+
+		preset->atoms[i].name = strdup(name);
+		if (!preset->atoms[i].name)
+			return -ENOMEM;
+	}
+	return 0;
+}
+
 static int append_var_preset(struct var_preset **presets, int *cnt, const char *expr)
 {
 	void *tmp;
 	struct var_preset *cur;
-	char var[256], val[256], *val_end;
-	long long value;
-	int n;
+	char var[256], val[256];
+	int n, err;
 
 	tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets));
 	if (!tmp)
@@ -1613,32 +1675,18 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
 		return -EINVAL;
 	}
 
-	if (val[0] == '-' || isdigit(val[0])) {
-		/* must be a number */
-		errno = 0;
-		value = strtoll(val, &val_end, 0);
-		if (errno == ERANGE) {
-			errno = 0;
-			value = strtoull(val, &val_end, 0);
-		}
-		if (errno || *val_end != '\0') {
-			fprintf(stderr, "Failed to parse value '%s'\n", val);
-			return -EINVAL;
-		}
-		cur->ivalue = value;
-		cur->type = INTEGRAL;
-	} else {
-		/* if not a number, consider it enum value */
-		cur->svalue = strdup(val);
-		if (!cur->svalue)
-			return -ENOMEM;
-		cur->type = ENUMERATOR;
-	}
+	err = parse_rvalue(val, &cur->value);
+	if (err)
+		return err;
 
-	cur->name = strdup(var);
-	if (!cur->name)
+	cur->full_name = strdup(var);
+	if (!cur->full_name)
 		return -ENOMEM;
 
+	err = parse_var_atoms(var, cur);
+	if (err)
+		return err;
+
 	return 0;
 }
 
@@ -1765,22 +1813,20 @@ const int btf_find_member(const struct btf *btf,
 }
 
 static int adjust_var_secinfo(struct btf *btf, const struct btf_type *t,
-			      struct btf_var_secinfo *sinfo, const char *var)
+			      struct btf_var_secinfo *sinfo, struct var_preset *preset)
 {
-	char expr[256], *saveptr;
 	const struct btf_type *base_type, *member_type;
-	int err, member_tid;
-	char *name;
+	int err, member_tid, i;
 	__u32 member_offset = 0;
 
 	base_type = btf__type_by_id(btf, btf__resolve_type(btf, t->type));
-	snprintf(expr, sizeof(expr), "%s", var);
-	strtok_r(expr, ".", &saveptr);
 
-	while ((name = strtok_r(NULL, ".", &saveptr))) {
-		err = btf_find_member(btf, base_type, 0, name, &member_tid, &member_offset);
+	for (i = 1; i < preset->atom_count; ++i) {
+		err = btf_find_member(btf, base_type, 0, preset->atoms[i].name,
+				      &member_tid, &member_offset);
 		if (err) {
-			fprintf(stderr, "Could not find member %s for variable %s\n", name, var);
+			fprintf(stderr, "Could not find member %s for variable %s\n",
+				preset->atoms[i].name, preset->atoms[i - 1].name);
 			return err;
 		}
 		member_type = btf__type_by_id(btf, member_tid);
@@ -1798,7 +1844,7 @@ static int set_global_var(struct bpf_object *obj, struct btf *btf,
 {
 	const struct btf_type *base_type;
 	void *ptr;
-	long long value = preset->ivalue;
+	long long value = preset->value.ivalue;
 	size_t size;
 
 	base_type = btf__type_by_id(btf, btf__resolve_type(btf, sinfo->type));
@@ -1812,17 +1858,18 @@ static int set_global_var(struct bpf_object *obj, struct btf *btf,
 		return -EINVAL;
 	}
 
-	if (preset->type == ENUMERATOR) {
+	if (preset->value.type == ENUMERATOR) {
 		if (btf_is_any_enum(base_type)) {
-			if (enum_value_from_name(btf, base_type, preset->svalue, &value)) {
+			if (enum_value_from_name(btf, base_type, preset->value.svalue, &value)) {
 				fprintf(stderr,
 					"Failed to find integer value for enum element %s\n",
-					preset->svalue);
+					preset->value.svalue);
 				return -EINVAL;
 			}
 		} else {
 			fprintf(stderr, "Value %s is not supported for type %s\n",
-				preset->svalue, btf__name_by_offset(btf, base_type->name_off));
+				preset->value.svalue,
+				btf__name_by_offset(btf, base_type->name_off));
 			return -EINVAL;
 		}
 	}
@@ -1889,20 +1936,16 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
 		for (j = 0; j < n; ++j, ++sinfo) {
 			const struct btf_type *var_type = btf__type_by_id(btf, sinfo->type);
 			const char *var_name;
-			int var_len;
 
 			if (!btf_is_var(var_type))
 				continue;
 
 			var_name = btf__name_by_offset(btf, var_type->name_off);
-			var_len = strlen(var_name);
 
 			for (k = 0; k < npresets; ++k) {
 				struct btf_var_secinfo tmp_sinfo;
 
-				if (strncmp(var_name, presets[k].name, var_len) != 0 ||
-				    (presets[k].name[var_len] != '\0' &&
-				     presets[k].name[var_len] != '.'))
+				if (strcmp(var_name, presets[k].atoms[0].name) != 0)
 					continue;
 
 				if (presets[k].applied) {
@@ -1912,7 +1955,7 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
 				}
 				tmp_sinfo = *sinfo;
 				err = adjust_var_secinfo(btf, var_type,
-							 &tmp_sinfo, presets[k].name);
+							 &tmp_sinfo, presets + k);
 				if (err)
 					return err;
 
@@ -1927,7 +1970,7 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
 	for (i = 0; i < npresets; ++i) {
 		if (!presets[i].applied) {
 			fprintf(stderr, "Global variable preset %s has not been applied\n",
-				presets[i].name);
+				presets[i].full_name);
 		}
 		presets[i].applied = false;
 	}
@@ -3061,7 +3104,7 @@ static int handle_replay_mode(void)
 
 int main(int argc, char **argv)
 {
-	int err = 0, i;
+	int err = 0, i, j;
 
 	if (argp_parse(&argp, argc, argv, 0, NULL, NULL))
 		return 1;
@@ -3120,9 +3163,12 @@ int main(int argc, char **argv)
 	}
 	free(env.deny_filters);
 	for (i = 0; i < env.npresets; ++i) {
-		free(env.presets[i].name);
-		if (env.presets[i].type == ENUMERATOR)
-			free(env.presets[i].svalue);
+		free(env.presets[i].full_name);
+		for (j = 0; j < env.presets[i].atom_count; ++j)
+			free(env.presets[i].atoms[j].name);
+		free(env.presets[i].atoms);
+		if (env.presets[i].value.type == ENUMERATOR)
+			free(env.presets[i].value.svalue);
 	}
 	free(env.presets);
 	return -err;
-- 
2.50.0

[PATCH bpf-next v5 2/3] selftests/bpf: support array presets in veristat

[Mykyta Yatsenko]

From: Mykyta Yatsenko <yatsenko@meta.com>

Implement support for presetting values for array elements in veristat.
For example:
```
sudo ./veristat set_global_vars.bpf.o -G "arr[3] = 1"
```
Arrays of structures and structure of arrays work, but each individual
scalar value has to be set separately: `foo[1].bar[2] = value`.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
 tools/testing/selftests/bpf/veristat.c | 239 +++++++++++++++++++------
 1 file changed, 189 insertions(+), 50 deletions(-)

diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
index 483442c08ecf..9c67adcf0a33 100644
--- a/tools/testing/selftests/bpf/veristat.c
+++ b/tools/testing/selftests/bpf/veristat.c
@@ -165,7 +165,11 @@ struct rvalue {
 };
 
 struct field_access {
-	char *name;
+	enum { FIELD_NAME, ARRAY_INDEX } type;
+	union {
+		char *name;
+		struct rvalue index;
+	};
 };
 
 struct var_preset {
@@ -1629,28 +1633,60 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
 		free(buf);
 
 	return 0;
-};
+}
+
+static int append_preset_atom(struct var_preset *preset, char *value, bool is_index)
+{
+	struct field_access *tmp;
+	int i = preset->atom_count;
+	int err;
+
+	tmp = reallocarray(preset->atoms, i + 1, sizeof(*preset->atoms));
+	if (!tmp)
+		return -ENOMEM;
+
+	preset->atoms = tmp;
+	preset->atom_count++;
+
+	if (is_index) {
+		preset->atoms[i].type = ARRAY_INDEX;
+		err = parse_rvalue(value, &preset->atoms[i].index);
+		if (err)
+			return err;
+	} else {
+		preset->atoms[i].type = FIELD_NAME;
+		preset->atoms[i].name = strdup(value);
+		if (!preset->atoms[i].name)
+			return -ENOMEM;
+	}
+	return 0;
+}
 
 static int parse_var_atoms(const char *full_var, struct var_preset *preset)
 {
-	char expr[256], *name, *saveptr;
+	char expr[256], var[256], *name, *saveptr;
+	int n, len, off;
 
 	snprintf(expr, sizeof(expr), "%s", full_var);
 	preset->atom_count = 0;
 	while ((name = strtok_r(preset->atom_count ? NULL : expr, ".", &saveptr))) {
-		struct field_access *tmp;
-		int i = preset->atom_count;
-
-		tmp = reallocarray(preset->atoms, i + 1, sizeof(*preset->atoms));
-		if (!tmp)
-			return -ENOMEM;
-
-		preset->atoms = tmp;
-		preset->atom_count++;
+		len = strlen(name);
+		/* parse variable name */
+		if (sscanf(name, "%[a-zA-Z0-9_] %n", var, &off) != 1) {
+			fprintf(stderr, "Can't parse %s\n", name);
+			return -EINVAL;
+		}
+		append_preset_atom(preset, var, false);
 
-		preset->atoms[i].name = strdup(name);
-		if (!preset->atoms[i].name)
-			return -ENOMEM;
+		/* parse optional array indexes */
+		while (off < len) {
+			if (sscanf(name + off, " [ %[a-zA-Z0-9_] ] %n", var, &n) != 1) {
+				fprintf(stderr, "Can't parse %s as index\n", name + off);
+				return -EINVAL;
+			}
+			append_preset_atom(preset, var, true);
+			off += n;
+		}
 	}
 	return 0;
 }
@@ -1660,7 +1696,7 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
 	void *tmp;
 	struct var_preset *cur;
 	char var[256], val[256];
-	int n, err;
+	int n, err, i;
 
 	tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets));
 	if (!tmp)
@@ -1670,10 +1706,16 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
 	memset(cur, 0, sizeof(*cur));
 	(*cnt)++;
 
-	if (sscanf(expr, "%s = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
+	if (sscanf(expr, " %[][a-zA-Z0-9_. ] = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
 		fprintf(stderr, "Failed to parse expression '%s'\n", expr);
 		return -EINVAL;
 	}
+	/* Remove trailing spaces from var, as scanf may add those */
+	for (i = strlen(var) - 1; i > 0; --i) {
+		if (!isspace(var[i]))
+			break;
+		var[i] = '\0';
+	}
 
 	err = parse_rvalue(val, &cur->value);
 	if (err)
@@ -1763,22 +1805,96 @@ static bool is_preset_supported(const struct btf_type *t)
 	return btf_is_int(t) || btf_is_enum(t) || btf_is_enum64(t);
 }
 
-const int btf_find_member(const struct btf *btf,
-			  const struct btf_type *parent_type,
-			  __u32 parent_offset,
-			  const char *member_name,
-			  int *member_tid,
-			  __u32 *member_offset)
+static int find_enum_value(const struct btf *btf, const char *name, long long *value)
+{
+	const struct btf_type *t;
+	int cnt, i;
+	long long lvalue;
+
+	cnt = btf__type_cnt(btf);
+	for (i = 1; i != cnt; ++i) {
+		t = btf__type_by_id(btf, i);
+
+		if (!btf_is_any_enum(t))
+			continue;
+
+		if (enum_value_from_name(btf, t, name, &lvalue) == 0) {
+			*value = lvalue;
+			return 0;
+		}
+	}
+	return -ESRCH;
+}
+
+static int resolve_rvalue(struct btf *btf, const struct rvalue *rvalue, long long *result)
+{
+	int err = 0;
+
+	switch (rvalue->type) {
+	case INTEGRAL:
+		*result = rvalue->ivalue;
+		return 0;
+	case ENUMERATOR:
+		err = find_enum_value(btf, rvalue->svalue, result);
+		if (err) {
+			fprintf(stderr, "Can't resolve enum value %s\n", rvalue->svalue);
+			return err;
+		}
+		return 0;
+	default:
+		fprintf(stderr, "Unknown rvalue type\n");
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+static int adjust_var_secinfo_array(struct btf *btf, int tid, struct field_access *atom,
+				    const char *array_name, struct btf_var_secinfo *sinfo)
+{
+	const struct btf_type *t;
+	struct btf_array *barr;
+	long long idx;
+	int err;
+
+	tid = btf__resolve_type(btf, tid);
+	t = btf__type_by_id(btf, tid);
+	if (!btf_is_array(t)) {
+		fprintf(stderr, "Array index is not expected for %s\n",
+			array_name);
+		return -EINVAL;
+	}
+	barr = btf_array(t);
+	err = resolve_rvalue(btf, &atom->index, &idx);
+	if (err)
+		return err;
+	if (idx < 0 || idx >= barr->nelems) {
+		fprintf(stderr, "Array index %lld is out of bounds [0, %u]: %s\n",
+			idx, barr->nelems, array_name);
+		return -EINVAL;
+	}
+	sinfo->size = btf__resolve_size(btf, barr->type);
+	sinfo->offset += sinfo->size * idx;
+	sinfo->type = btf__resolve_type(btf, barr->type);
+	return 0;
+}
+
+static int adjust_var_secinfo_member(const struct btf *btf,
+				     const struct btf_type *parent_type,
+				     __u32 parent_offset,
+				     const char *member_name,
+				     struct btf_var_secinfo *sinfo)
 {
 	int i;
 
-	if (!btf_is_composite(parent_type))
+	if (!btf_is_composite(parent_type)) {
+		fprintf(stderr, "Can't resolve field %s for non-composite type\n", member_name);
 		return -EINVAL;
+	}
 
 	for (i = 0; i < btf_vlen(parent_type); ++i) {
 		const struct btf_member *member;
 		const struct btf_type *member_type;
-		int tid;
+		int tid, off;
 
 		member = btf_members(parent_type) + i;
 		tid =  btf__resolve_type(btf, member->type);
@@ -1786,6 +1902,7 @@ const int btf_find_member(const struct btf *btf,
 			return -EINVAL;
 
 		member_type = btf__type_by_id(btf, tid);
+		off = parent_offset + member->offset;
 		if (member->name_off) {
 			const char *name = btf__name_by_offset(btf, member->name_off);
 
@@ -1795,15 +1912,16 @@ const int btf_find_member(const struct btf *btf,
 						name);
 					return -EINVAL;
 				}
-				*member_offset = parent_offset + member->offset;
-				*member_tid = tid;
+				sinfo->offset += off / 8;
+				sinfo->type = tid;
+				sinfo->size = member_type->size;
 				return 0;
 			}
 		} else if (btf_is_composite(member_type)) {
 			int err;
 
-			err = btf_find_member(btf, member_type, parent_offset + member->offset,
-					      member_name, member_tid, member_offset);
+			err = adjust_var_secinfo_member(btf, member_type, off,
+							member_name, sinfo);
 			if (!err)
 				return 0;
 		}
@@ -1815,26 +1933,39 @@ const int btf_find_member(const struct btf *btf,
 static int adjust_var_secinfo(struct btf *btf, const struct btf_type *t,
 			      struct btf_var_secinfo *sinfo, struct var_preset *preset)
 {
-	const struct btf_type *base_type, *member_type;
-	int err, member_tid, i;
-	__u32 member_offset = 0;
+	const struct btf_type *base_type;
+	const char *prev_name;
+	int err, i;
+	int tid;
+
+	assert(preset->atom_count > 0);
+	assert(preset->atoms[0].type == FIELD_NAME);
 
-	base_type = btf__type_by_id(btf, btf__resolve_type(btf, t->type));
+	tid = btf__resolve_type(btf, t->type);
+	base_type = btf__type_by_id(btf, tid);
+	prev_name = preset->atoms[0].name;
 
 	for (i = 1; i < preset->atom_count; ++i) {
-		err = btf_find_member(btf, base_type, 0, preset->atoms[i].name,
-				      &member_tid, &member_offset);
-		if (err) {
-			fprintf(stderr, "Could not find member %s for variable %s\n",
-				preset->atoms[i].name, preset->atoms[i - 1].name);
-			return err;
+		struct field_access *atom = preset->atoms + i;
+
+		switch (atom->type) {
+		case ARRAY_INDEX:
+			err = adjust_var_secinfo_array(btf, tid, atom, prev_name, sinfo);
+			break;
+		case FIELD_NAME:
+			err = adjust_var_secinfo_member(btf, base_type, 0, atom->name, sinfo);
+			prev_name = atom->name;
+			break;
+		default:
+			fprintf(stderr, "Unknown field_access type\n");
+			return -EOPNOTSUPP;
 		}
-		member_type = btf__type_by_id(btf, member_tid);
-		sinfo->offset += member_offset / 8;
-		sinfo->size = member_type->size;
-		sinfo->type = member_tid;
-		base_type = member_type;
+		if (err)
+			return err;
+		base_type = btf__type_by_id(btf, sinfo->type);
+		tid = sinfo->type;
 	}
+
 	return 0;
 }
 
@@ -1853,8 +1984,8 @@ static int set_global_var(struct bpf_object *obj, struct btf *btf,
 		return -EINVAL;
 	}
 	if (!is_preset_supported(base_type)) {
-		fprintf(stderr, "Setting value for type %s is not supported\n",
-			btf__name_by_offset(btf, base_type->name_off));
+		fprintf(stderr, "Can't set %s. Only ints and enums are supported\n",
+			preset->full_name);
 		return -EINVAL;
 	}
 
@@ -1971,6 +2102,7 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
 		if (!presets[i].applied) {
 			fprintf(stderr, "Global variable preset %s has not been applied\n",
 				presets[i].full_name);
+			err = -EINVAL;
 		}
 		presets[i].applied = false;
 	}
@@ -3164,11 +3296,18 @@ int main(int argc, char **argv)
 	free(env.deny_filters);
 	for (i = 0; i < env.npresets; ++i) {
 		free(env.presets[i].full_name);
-		for (j = 0; j < env.presets[i].atom_count; ++j)
-			free(env.presets[i].atoms[j].name);
+		for (j = 0; j < env.presets[i].atom_count; ++j) {
+			switch (env.presets[i].atoms[j].type) {
+			case FIELD_NAME:
+				free(env.presets[i].atoms[j].name);
+				break;
+			case ARRAY_INDEX:
+				if (env.presets[i].atoms[j].index.type == ENUMERATOR)
+					free(env.presets[i].atoms[j].index.svalue);
+				break;
+			}
+		}
 		free(env.presets[i].atoms);
-		if (env.presets[i].value.type == ENUMERATOR)
-			free(env.presets[i].value.svalue);
 	}
 	free(env.presets);
 	return -err;
-- 
2.50.0

[PATCH bpf-next v5 3/3] selftests/bpf: test array presets in veristat

[Mykyta Yatsenko]

From: Mykyta Yatsenko <yatsenko@meta.com>

Modify existing veristat tests to verify that array presets are applied
as expected.
Introduce few negative tests as well to check that common error modes
are handled.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
 .../selftests/bpf/prog_tests/test_veristat.c  | 127 +++++++++++++++++-
 .../selftests/bpf/progs/set_global_vars.c     |  56 +++++---
 2 files changed, 159 insertions(+), 24 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_veristat.c b/tools/testing/selftests/bpf/prog_tests/test_veristat.c
index 47b56c258f3f..367f47e4a936 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_veristat.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_veristat.c
@@ -60,13 +60,19 @@ static void test_set_global_vars_succeeds(void)
 	    " -G \"var_s8 = -128\" "\
 	    " -G \"var_u8 = 255\" "\
 	    " -G \"var_ea = EA2\" "\
-	    " -G \"var_eb = EB2\" "\
-	    " -G \"var_ec = EC2\" "\
+	    " -G \"var_eb  =  EB2\" "\
+	    " -G \"var_ec=EC2\" "\
 	    " -G \"var_b = 1\" "\
-	    " -G \"struct1.struct2.u.var_u8 = 170\" "\
+	    " -G \"struct1[2].struct2[1][2].u.var_u8[2]=170\" "\
 	    " -G \"union1.struct3.var_u8_l = 0xaa\" "\
 	    " -G \"union1.struct3.var_u8_h = 0xaa\" "\
-	    "-vl2 > %s", fix->veristat, fix->tmpfile);
+	    " -G \"arr[3]= 171\" "	\
+	    " -G \"arr[EA2] =172\" "	\
+	    " -G \"enum_arr[EC2]=EA3\" " \
+	    " -G \"three_d[31][7][EA2]=173\"" \
+	    " -G \"struct1[2].struct2[1][2].u.mat[5][3]=174\" " \
+	    " -G \"struct11 [ 7 ] [ 5 ] .struct2[0][1].u.mat[3][0] = 175\" " \
+	    " -vl2 > %s", fix->veristat, fix->tmpfile);
 
 	read(fix->fd, fix->output, fix->sz);
 	__CHECK_STR("_w=0xf000000000000001 ", "var_s64 = 0xf000000000000001");
@@ -81,8 +87,14 @@ static void test_set_global_vars_succeeds(void)
 	__CHECK_STR("_w=12 ", "var_eb = EB2");
 	__CHECK_STR("_w=13 ", "var_ec = EC2");
 	__CHECK_STR("_w=1 ", "var_b = 1");
-	__CHECK_STR("_w=170 ", "struct1.struct2.u.var_u8 = 170");
+	__CHECK_STR("_w=170 ", "struct1[2].struct2[1][2].u.var_u8[2]=170");
 	__CHECK_STR("_w=0xaaaa ", "union1.var_u16 = 0xaaaa");
+	__CHECK_STR("_w=171 ", "arr[3]= 171");
+	__CHECK_STR("_w=172 ", "arr[EA2] =172");
+	__CHECK_STR("_w=10 ", "enum_arr[EC2]=EA3");
+	__CHECK_STR("_w=173 ", "matrix[31][7][11]=173");
+	__CHECK_STR("_w=174 ", "struct1[2].struct2[1][2].u.mat[5][3]=174");
+	__CHECK_STR("_w=175 ", "struct11[7][5].struct2[0][1].u.mat[3][0]=175");
 
 out:
 	teardown_fixture(fix);
@@ -129,6 +141,95 @@ static void test_set_global_vars_out_of_range(void)
 	teardown_fixture(fix);
 }
 
+static void test_unsupported_ptr_array_type(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"ptr_arr[0] = 0\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	read(fix->fd, fix->output, fix->sz);
+	__CHECK_STR("Can't set ptr_arr[0]. Only ints and enums are supported", "ptr_arr");
+
+out:
+	teardown_fixture(fix);
+}
+
+static void test_array_out_of_bounds(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"arr[99] = 0\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	read(fix->fd, fix->output, fix->sz);
+	__CHECK_STR("Array index 99 is out of bounds", "arr[99]");
+
+out:
+	teardown_fixture(fix);
+}
+
+static void test_array_index_not_found(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"arr[EG2] = 0\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	read(fix->fd, fix->output, fix->sz);
+	__CHECK_STR("Can't resolve enum value EG2", "arr[EG2]");
+
+out:
+	teardown_fixture(fix);
+}
+
+static void test_array_index_for_non_array(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"var_b[0] = 1\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	pread(fix->fd, fix->output, fix->sz, 0);
+	__CHECK_STR("Array index is not expected for var_b", "var_b[0] = 1");
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"union1.struct3[0].var_u8_l=1\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	pread(fix->fd, fix->output, fix->sz, 0);
+	__CHECK_STR("Array index is not expected for struct3", "union1.struct3[0].var_u8_l=1");
+
+out:
+	teardown_fixture(fix);
+}
+
+static void test_no_array_index_for_array(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"arr = 1\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	pread(fix->fd, fix->output, fix->sz, 0);
+	__CHECK_STR("Can't set arr. Only ints and enums are supported", "arr = 1");
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"struct1[0].struct2.u.var_u8[2]=1\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	pread(fix->fd, fix->output, fix->sz, 0);
+	__CHECK_STR("Can't resolve field u for non-composite type", "struct1[0].struct2.u.var_u8[2]=1");
+
+out:
+	teardown_fixture(fix);
+}
+
 void test_veristat(void)
 {
 	if (test__start_subtest("set_global_vars_succeeds"))
@@ -139,6 +240,22 @@ void test_veristat(void)
 
 	if (test__start_subtest("set_global_vars_from_file_succeeds"))
 		test_set_global_vars_from_file_succeeds();
+
+	if (test__start_subtest("test_unsupported_ptr_array_type"))
+		test_unsupported_ptr_array_type();
+
+	if (test__start_subtest("test_array_out_of_bounds"))
+		test_array_out_of_bounds();
+
+	if (test__start_subtest("test_array_index_not_found"))
+		test_array_index_not_found();
+
+	if (test__start_subtest("test_array_index_for_non_array"))
+		test_array_index_for_non_array();
+
+	if (test__start_subtest("test_no_array_index_for_array"))
+		test_no_array_index_for_array();
+
 }
 
 #undef __CHECK_STR
diff --git a/tools/testing/selftests/bpf/progs/set_global_vars.c b/tools/testing/selftests/bpf/progs/set_global_vars.c
index 90f5656c3991..ebaef28b2cb3 100644
--- a/tools/testing/selftests/bpf/progs/set_global_vars.c
+++ b/tools/testing/selftests/bpf/progs/set_global_vars.c
@@ -7,22 +7,30 @@
 
 char _license[] SEC("license") = "GPL";
 
-enum Enum { EA1 = 0, EA2 = 11 };
+typedef __s32 s32;
+typedef s32 i32;
+typedef __u8 u8;
+
+enum Enum { EA1 = 0, EA2 = 11, EA3 = 10 };
 enum Enumu64 {EB1 = 0llu, EB2 = 12llu };
 enum Enums64 { EC1 = 0ll, EC2 = 13ll };
 
 const volatile __s64 var_s64 = -1;
 const volatile __u64 var_u64 = 0;
-const volatile __s32 var_s32 = -1;
+const volatile i32 var_s32 = -1;
 const volatile __u32 var_u32 = 0;
 const volatile __s16 var_s16 = -1;
 const volatile __u16 var_u16 = 0;
 const volatile __s8 var_s8 = -1;
-const volatile __u8 var_u8 = 0;
+const volatile u8 var_u8 = 0;
 const volatile enum Enum var_ea = EA1;
 const volatile enum Enumu64 var_eb = EB1;
 const volatile enum Enums64 var_ec = EC1;
 const volatile bool var_b = false;
+const volatile i32 arr[32];
+const volatile enum Enum enum_arr[32];
+const volatile i32 three_d[47][19][17];
+const volatile i32 *ptr_arr[32];
 
 struct Struct {
 	int:16;
@@ -35,34 +43,38 @@ struct Struct {
 		volatile struct {
 			const int:1;
 			union {
-				const volatile __u8 var_u8;
+				const volatile u8 var_u8[3];
 				const volatile __s16 filler3;
 				const int:1;
+				s32 mat[7][5];
 			} u;
 		};
-	} struct2;
+	} struct2[2][4];
 };
 
 const volatile __u32 stru = 0; /* same prefix as below */
-const volatile struct Struct struct1 = {.struct2 = {.u = {.var_u8 = 1}}};
+const volatile struct Struct struct1[3];
+const volatile struct Struct struct11[11][7];
 
-union Union {
-	__u16 var_u16;
-	struct Struct3 {
-		struct {
-			__u8 var_u8_l;
-		};
+struct Struct3 {
+	struct {
+		u8 var_u8_l;
+	};
+	struct {
 		struct {
-			struct {
-				__u8 var_u8_h;
-			};
+			u8 var_u8_h;
 		};
-	} struct3;
+	};
 };
 
-const volatile union Union union1 = {.var_u16 = -1};
+typedef struct Struct3 Struct3_t;
 
-char arr[4] = {0};
+union Union {
+	__u16 var_u16;
+	Struct3_t struct3;
+};
+
+const volatile union Union union1 = {.var_u16 = -1};
 
 SEC("socket")
 int test_set_globals(void *ctx)
@@ -81,8 +93,14 @@ int test_set_globals(void *ctx)
 	a = var_eb;
 	a = var_ec;
 	a = var_b;
-	a = struct1.struct2.u.var_u8;
+	a = struct1[2].struct2[1][2].u.var_u8[2];
 	a = union1.var_u16;
+	a = arr[3];
+	a = arr[EA2];
+	a = enum_arr[EC2];
+	a = three_d[31][7][EA2];
+	a = struct1[2].struct2[1][2].u.mat[5][3];
+	a = struct11[7][5].struct2[0][1].u.mat[3][0];
 
 	return a;
 }
-- 
2.50.0

Re: [PATCH bpf-next v5 1/3] selftests/bpf: separate var preset parsing in veristat

[Eduard Zingerman]

On Wed, 2025-06-25 at 17:59 +0100, Mykyta Yatsenko wrote:
> From: Mykyta Yatsenko <yatsenko@meta.com>
> 
> Refactor var preset parsing in veristat to simplify implementation.
> Prepare parsed variable beforehand so that parsing logic is separated
> from functionality of calculating offsets and searching fields.
> Introduce rvalue struct, storing either int or enum (string value),
> will be reused in the next patch, extract parsing rvalue into a
> separate function.
> 
> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
> ---

This patch is the same as in v4, please don't drop acks.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

[...]

Re: [PATCH bpf-next v5 3/3] selftests/bpf: test array presets in veristat

[Eduard Zingerman]

On Wed, 2025-06-25 at 17:59 +0100, Mykyta Yatsenko wrote:
> From: Mykyta Yatsenko <yatsenko@meta.com>
> 
> Modify existing veristat tests to verify that array presets are applied
> as expected.
> Introduce few negative tests as well to check that common error modes
> are handled.
> 
> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
> ---

Please don't drop acks, it helps to navigating the series, e.g. for
this one I had to diff the diffs to figure out if it is the same I've
acked in v4.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

[...]

Re: [PATCH bpf-next v5 2/3] selftests/bpf: support array presets in veristat

[Eduard Zingerman]

On Wed, 2025-06-25 at 17:59 +0100, Mykyta Yatsenko wrote:
> From: Mykyta Yatsenko <yatsenko@meta.com>
> 
> Implement support for presetting values for array elements in veristat.
> For example:
> ```
> sudo ./veristat set_global_vars.bpf.o -G "arr[3] = 1"
> ```
> Arrays of structures and structure of arrays work, but each individual
> scalar value has to be set separately: `foo[1].bar[2] = value`.
> 
> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
> ---

This looks great, I have a few minor nits but let's land this patch-set.
Maybe fix error reporting below as a follow-up.
New array offset computation logic is much simpler to grasp.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

---

Nit: this signals an error:

        $ ./veristat -G "   arr[   fff  ]      = 1" set_global_vars.bpf.o
        Processing 'set_global_vars.bpf.o'...
        Can't resolve enum value fff
        Failed to set global variables -3
        Failed to process 'set_global_vars.bpf.o': -3
      
     but this does not:

        $ ./veristat -G "   arr[   11111111111111111111111111111  ]      = 1" set_global_vars.bpf.o
        Failed to parse value '11111111111111111111111111111'
        Processing 'set_global_vars.bpf.o'...
        File                   Program           Verdict  Duration (us)  Insns  States  Program size  Jited size
        ---------------------  ----------------  -------  -------------  -----  ------  ------------  ----------
        set_global_vars.bpf.o  test_set_globals  success             27     64       0            82           0
        ---------------------  ----------------  -------  -------------  -----  ------  ------------  ----------
        Done. Processed 1 files, 0 programs. Skipped 1 files, 0 programs.


>  tools/testing/selftests/bpf/veristat.c | 239 +++++++++++++++++++------
>  1 file changed, 189 insertions(+), 50 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
> index 483442c08ecf..9c67adcf0a33 100644
> --- a/tools/testing/selftests/bpf/veristat.c
> +++ b/tools/testing/selftests/bpf/veristat.c

[...]

> @@ -1670,10 +1706,16 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
>  	memset(cur, 0, sizeof(*cur));
>  	(*cnt)++;
>  
> -	if (sscanf(expr, "%s = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
> +	if (sscanf(expr, " %[][a-zA-Z0-9_. ] = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
>  		fprintf(stderr, "Failed to parse expression '%s'\n", expr);
>  		return -EINVAL;
>  	}
> +	/* Remove trailing spaces from var, as scanf may add those */
> +	for (i = strlen(var) - 1; i > 0; --i) {
> +		if (!isspace(var[i]))
> +			break;
> +		var[i] = '\0';
> +	}

Nit: It appears, this sequence is needed only for nicer error reporting,
     I'd just drop it.

>  
>  	err = parse_rvalue(val, &cur->value);
>  	if (err)

[...]

> @@ -3164,11 +3296,18 @@ int main(int argc, char **argv)
>  	free(env.deny_filters);
>  	for (i = 0; i < env.npresets; ++i) {
>  		free(env.presets[i].full_name);
> -		for (j = 0; j < env.presets[i].atom_count; ++j)
> -			free(env.presets[i].atoms[j].name);
> +		for (j = 0; j < env.presets[i].atom_count; ++j) {
> +			switch (env.presets[i].atoms[j].type) {
> +			case FIELD_NAME:
> +				free(env.presets[i].atoms[j].name);
> +				break;
> +			case ARRAY_INDEX:
> +				if (env.presets[i].atoms[j].index.type == ENUMERATOR)
> +					free(env.presets[i].atoms[j].index.svalue);
> +				break;
> +			}
> +		}

Nit: removing union in `struct field_access` would simplify this loop to:

		for (j = 0; j < env.presets[i].atom_count; ++j) {
			free(env.presets[i].atoms[j].name);
			free(env.presets[i].atoms[j].index.svalue);
		}

     (assuming zero initialization).

>  		free(env.presets[i].atoms);
> -		if (env.presets[i].value.type == ENUMERATOR)
> -			free(env.presets[i].value.svalue);
>  	}
>  	free(env.presets);
>  	return -err;

Re: [PATCH bpf-next v5 2/3] selftests/bpf: support array presets in veristat

[Andrii Nakryiko]

On Wed, Jun 25, 2025 at 2:46 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> On Wed, 2025-06-25 at 17:59 +0100, Mykyta Yatsenko wrote:
> > From: Mykyta Yatsenko <yatsenko@meta.com>
> >
> > Implement support for presetting values for array elements in veristat.
> > For example:
> > ```
> > sudo ./veristat set_global_vars.bpf.o -G "arr[3] = 1"
> > ```
> > Arrays of structures and structure of arrays work, but each individual
> > scalar value has to be set separately: `foo[1].bar[2] = value`.
> >
> > Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
> > ---
>
> This looks great, I have a few minor nits but let's land this patch-set.
> Maybe fix error reporting below as a follow-up.
> New array offset computation logic is much simpler to grasp.
>
> Acked-by: Eduard Zingerman <eddyz87@gmail.com>
>

Applied to bpf-next as is. Mykyta, please send a quick follow up
addressing Eduard's suggestions, and let's cut a new veristat release
on Github after that. Thanks!

> ---
>
> Nit: this signals an error:
>
>         $ ./veristat -G "   arr[   fff  ]      = 1" set_global_vars.bpf.o
>         Processing 'set_global_vars.bpf.o'...
>         Can't resolve enum value fff
>         Failed to set global variables -3
>         Failed to process 'set_global_vars.bpf.o': -3
>
>      but this does not:
>
>         $ ./veristat -G "   arr[   11111111111111111111111111111  ]      = 1" set_global_vars.bpf.o
>         Failed to parse value '11111111111111111111111111111'
>         Processing 'set_global_vars.bpf.o'...
>         File                   Program           Verdict  Duration (us)  Insns  States  Program size  Jited size
>         ---------------------  ----------------  -------  -------------  -----  ------  ------------  ----------
>         set_global_vars.bpf.o  test_set_globals  success             27     64       0            82           0
>         ---------------------  ----------------  -------  -------------  -----  ------  ------------  ----------
>         Done. Processed 1 files, 0 programs. Skipped 1 files, 0 programs.
>
>

[...]

Re: [PATCH bpf-next v5 0/3] Support array presets in veristat

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Wed, 25 Jun 2025 17:59:01 +0100 you wrote:
> From: Mykyta Yatsenko <yatsenko@meta.com>
> 
> This patch series implements support for array variable presets in
> veristat. Currently users can set values to global variables before
> loading BPF program, but not for arrays. With this change array
> elements are supported as well, for example:
> ```
> sudo ./veristat set_global_vars.bpf.o -G "arr[0] = 1"
> ```
> 
> [...]

Here is the summary with links:
  - [bpf-next,v5,1/3] selftests/bpf: separate var preset parsing in veristat
    https://git.kernel.org/bpf/bpf-next/c/be898cb5cbf4
  - [bpf-next,v5,2/3] selftests/bpf: support array presets in veristat
    https://git.kernel.org/bpf/bpf-next/c/edc99d0b021c
  - [bpf-next,v5,3/3] selftests/bpf: test array presets in veristat
    https://git.kernel.org/bpf/bpf-next/c/583588594b24

You are awesome, thank you!
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