Merge branch 'selftests-bpf-implement-setting-global-variables-in-veristat'

Mykyta Yatsenko says:

====================
selftests/bpf: implement setting global variables in veristat

From: Mykyta Yatsenko <yatsenko@meta.com>

To better verify some complex BPF programs by veristat, it would be useful
to preset global variables. This patch set implements this functionality
and introduces tests for veristat.

v4->v5
  * Rework parsing to use sscanf for integers
  * Addressing nits

v3->v4:
  * Fixing bug in set_global_var introduced by refactoring in previous patch set
  * Addressed nits from Eduard

v2->v3:
  * Reworked parsing of the presets, using sscanf to split into variable and
  value, but still use strtoll/strtoull to support range checks when parsing
  integers
  * Fix test failures for no_alu32 & cpuv4 by checking if veristat binary is in
  parent folder
  * Introduce __CHECK_STR macro for simplifying checks in test
  * Modify tests into sub-tests
====================

Link: https://patch.msgid.link/20250225163101.121043-1-mykyta.yatsenko5@gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -688,6 +688,7 @@ $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS)			\
 			     $(TRUNNER_EXTRA_OBJS) $$(BPFOBJ)		\
 			     $(RESOLVE_BTFIDS)				\
 			     $(TRUNNER_BPFTOOL)				\
+			     $(OUTPUT)/veristat				\
 			     | $(TRUNNER_BINARY)-extras
 	$$(call msg,BINARY,,$$@)
 	$(Q)$$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) $$(LDFLAGS) -o $$@

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

@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include <string.h>
+#include <stdio.h>
+
+#define __CHECK_STR(str, name)					    \
+	do {							    \
+		if (!ASSERT_HAS_SUBSTR(fix->output, (str), (name))) \
+			goto out;				    \
+	} while (0)
+
+struct fixture {
+	char tmpfile[80];
+	int fd;
+	char *output;
+	size_t sz;
+	char veristat[80];
+};
+
+static struct fixture *init_fixture(void)
+{
+	struct fixture *fix = malloc(sizeof(struct fixture));
+
+	/* for no_alu32 and cpuv4 veristat is in parent folder */
+	if (access("./veristat", F_OK) == 0)
+		strcpy(fix->veristat, "./veristat");
+	else if (access("../veristat", F_OK) == 0)
+		strcpy(fix->veristat, "../veristat");
+	else
+		PRINT_FAIL("Can't find veristat binary");
+
+	snprintf(fix->tmpfile, sizeof(fix->tmpfile), "/tmp/test_veristat.XXXXXX");
+	fix->fd = mkstemp(fix->tmpfile);
+	fix->sz = 1000000;
+	fix->output = malloc(fix->sz);
+	return fix;
+}
+
+static void teardown_fixture(struct fixture *fix)
+{
+	free(fix->output);
+	close(fix->fd);
+	remove(fix->tmpfile);
+	free(fix);
+}
+
+static void test_set_global_vars_succeeds(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS(out,
+	    "%s set_global_vars.bpf.o"\
+	    " -G \"var_s64 = 0xf000000000000001\" "\
+	    " -G \"var_u64 = 0xfedcba9876543210\" "\
+	    " -G \"var_s32 = -0x80000000\" "\
+	    " -G \"var_u32 = 0x76543210\" "\
+	    " -G \"var_s16 = -32768\" "\
+	    " -G \"var_u16 = 60652\" "\
+	    " -G \"var_s8 = -128\" "\
+	    " -G \"var_u8 = 255\" "\
+	    " -G \"var_ea = EA2\" "\
+	    " -G \"var_eb = EB2\" "\
+	    " -G \"var_ec = EC2\" "\
+	    " -G \"var_b = 1\" "\
+	    "-vl2 > %s", fix->veristat, fix->tmpfile);
+
+	read(fix->fd, fix->output, fix->sz);
+	__CHECK_STR("_w=0xf000000000000001 ", "var_s64 = 0xf000000000000001");
+	__CHECK_STR("_w=0xfedcba9876543210 ", "var_u64 = 0xfedcba9876543210");
+	__CHECK_STR("_w=0x80000000 ", "var_s32 = -0x80000000");
+	__CHECK_STR("_w=0x76543210 ", "var_u32 = 0x76543210");
+	__CHECK_STR("_w=0x8000 ", "var_s16 = -32768");
+	__CHECK_STR("_w=0xecec ", "var_u16 = 60652");
+	__CHECK_STR("_w=128 ", "var_s8 = -128");
+	__CHECK_STR("_w=255 ", "var_u8 = 255");
+	__CHECK_STR("_w=11 ", "var_ea = EA2");
+	__CHECK_STR("_w=12 ", "var_eb = EB2");
+	__CHECK_STR("_w=13 ", "var_ec = EC2");
+	__CHECK_STR("_w=1 ", "var_b = 1");
+
+out:
+	teardown_fixture(fix);
+}
+
+static void test_set_global_vars_from_file_succeeds(void)
+{
+	struct fixture *fix = init_fixture();
+	char input_file[80];
+	const char *vars = "var_s16 = -32768\nvar_u16 = 60652";
+	int fd;
+
+	snprintf(input_file, sizeof(input_file), "/tmp/veristat_input.XXXXXX");
+	fd = mkstemp(input_file);
+	if (!ASSERT_GE(fd, 0, "valid fd"))
+		goto out;
+
+	write(fd, vars, strlen(vars));
+	syncfs(fd);
+	SYS(out, "%s set_global_vars.bpf.o -G \"@%s\" -vl2 > %s",
+	    fix->veristat, input_file, fix->tmpfile);
+	read(fix->fd, fix->output, fix->sz);
+	__CHECK_STR("_w=0x8000 ", "var_s16 = -32768");
+	__CHECK_STR("_w=0xecec ", "var_u16 = 60652");
+
+out:
+	close(fd);
+	remove(input_file);
+	teardown_fixture(fix);
+}
+
+static void test_set_global_vars_out_of_range(void)
+{
+	struct fixture *fix = init_fixture();
+
+	SYS_FAIL(out,
+		 "%s set_global_vars.bpf.o -G \"var_s32 = 2147483648\" -vl2 2> %s",
+		 fix->veristat, fix->tmpfile);
+
+	read(fix->fd, fix->output, fix->sz);
+	__CHECK_STR("is out of range [-2147483648; 2147483647]", "out of range");
+
+out:
+	teardown_fixture(fix);
+}
+
+void test_veristat(void)
+{
+	if (test__start_subtest("set_global_vars_succeeds"))
+		test_set_global_vars_succeeds();
+
+	if (test__start_subtest("set_global_vars_out_of_range"))
+		test_set_global_vars_out_of_range();
+
+	if (test__start_subtest("set_global_vars_from_file_succeeds"))
+		test_set_global_vars_from_file_succeeds();
+}
+
+#undef __CHECK_STR

tools/testing/selftests/bpf/progs/set_global_vars.c

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+#include "bpf_experimental.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include <stdbool.h>
+
+char _license[] SEC("license") = "GPL";
+
+enum Enum { EA1 = 0, EA2 = 11 };
+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 __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 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;
+
+char arr[4] = {0};
+
+SEC("socket")
+int test_set_globals(void *ctx)
+{
+	volatile __s8 a;
+
+	a = var_s64;
+	a = var_u64;
+	a = var_s32;
+	a = var_u32;
+	a = var_s16;
+	a = var_u16;
+	a = var_s8;
+	a = var_u8;
+	a = var_ea;
+	a = var_eb;
+	a = var_ec;
+	a = var_b;
+	return a;
+}

tools/testing/selftests/bpf/test_progs.h

@@ -427,6 +427,14 @@ void hexdump(const char *prefix, const void *buf, size_t len);
 			goto goto_label;				\
 	})
 
+#define SYS_FAIL(goto_label, fmt, ...)					\
+	({								\
+		char cmd[1024];						\
+		snprintf(cmd, sizeof(cmd), fmt, ##__VA_ARGS__);		\
+		if (!ASSERT_NEQ(0, system(cmd), cmd))			\
+			goto goto_label;				\
+	})
+
 #define ALL_TO_DEV_NULL " >/dev/null 2>&1"
 
 #define SYS_NOFAIL(fmt, ...)						\

tools/testing/selftests/bpf/veristat.c

@@ -3,6 +3,7 @@
 #define _GNU_SOURCE
 #include <argp.h>
 #include <libgen.h>
+#include <ctype.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sched.h>
@@ -154,6 +155,16 @@ struct filter {
 	bool abs;
 };
 
+struct var_preset {
+	char *name;
+	enum { INTEGRAL, ENUMERATOR } type;
+	union {
+		long long ivalue;
+		char *svalue;
+	};
+	bool applied;
+};
+
 static struct env {
 	char **filenames;
 	int filename_cnt;
@@ -195,6 +206,8 @@ static struct env {
 	int progs_processed;
 	int progs_skipped;
 	int top_src_lines;
+	struct var_preset *presets;
+	int npresets;
 } env;
 
 static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
@@ -246,12 +259,15 @@ static const struct argp_option opts[] = {
 	{ "test-reg-invariants", 'r', NULL, 0,
 	  "Force BPF verifier failure on register invariant violation (BPF_F_TEST_REG_INVARIANTS program flag)" },
 	{ "top-src-lines", 'S', "N", 0, "Emit N most frequent source code lines" },
+	{ "set-global-vars", 'G', "GLOBAL", 0, "Set global variables provided in the expression, for example \"var1 = 1\"" },
 	{},
 };
 
 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 int append_var_preset(struct var_preset **presets, int *cnt, const char *expr);
+static int append_var_preset_file(const char *filename);
 
 static error_t parse_arg(int key, char *arg, struct argp_state *state)
 {
@@ -353,6 +369,17 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 			argp_usage(state);
 		}
 		break;
+	case 'G': {
+		if (arg[0] == '@')
+			err = append_var_preset_file(arg + 1);
+		else
+			err = append_var_preset(&env.presets, &env.npresets, arg);
+		if (err) {
+			fprintf(stderr, "Failed to parse global variable presets: %s\n", arg);
+			return err;
+		}
+		break;
+	}
 	case ARGP_KEY_ARG:
 		tmp = realloc(env.filenames, (env.filename_cnt + 1) * sizeof(*env.filenames));
 		if (!tmp)
@@ -632,7 +659,7 @@ static int append_filter_file(const char *path)
 	f = fopen(path, "r");
 	if (!f) {
 		err = -errno;
-		fprintf(stderr, "Failed to open filters in '%s': %d\n", path, err);
+		fprintf(stderr, "Failed to open filters in '%s': %s\n", path, strerror(err));
 		return err;
 	}
 
@@ -1292,6 +1319,261 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
 	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;
+
+	tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets));
+	if (!tmp)
+		return -ENOMEM;
+	*presets = tmp;
+	cur = &(*presets)[*cnt];
+	memset(cur, 0, sizeof(*cur));
+	(*cnt)++;
+
+	if (sscanf(expr, "%s = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
+		fprintf(stderr, "Failed to parse expression '%s'\n", expr);
+		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;
+	}
+
+	cur->name = strdup(var);
+	if (!cur->name)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int append_var_preset_file(const char *filename)
+{
+	char buf[1024];
+	FILE *f;
+	int err = 0;
+
+	f = fopen(filename, "rt");
+	if (!f) {
+		err = -errno;
+		fprintf(stderr, "Failed to open presets in '%s': %s\n", filename, strerror(err));
+		return -EINVAL;
+	}
+
+	while (fscanf(f, " %1023[^\n]\n", buf) == 1) {
+		if (buf[0] == '\0' || buf[0] == '#')
+			continue;
+
+		err = append_var_preset(&env.presets, &env.npresets, buf);
+		if (err)
+			goto cleanup;
+	}
+
+cleanup:
+	fclose(f);
+	return err;
+}
+
+static bool is_signed_type(const struct btf_type *t)
+{
+	if (btf_is_int(t))
+		return btf_int_encoding(t) & BTF_INT_SIGNED;
+	if (btf_is_any_enum(t))
+		return btf_kflag(t);
+	return true;
+}
+
+static int enum_value_from_name(const struct btf *btf, const struct btf_type *t,
+				const char *evalue, long long *retval)
+{
+	if (btf_is_enum(t)) {
+		struct btf_enum *e = btf_enum(t);
+		int i, n = btf_vlen(t);
+
+		for (i = 0; i < n; ++i, ++e) {
+			const char *cur_name = btf__name_by_offset(btf, e->name_off);
+
+			if (strcmp(cur_name, evalue) == 0) {
+				*retval = e->val;
+				return 0;
+			}
+		}
+	} else if (btf_is_enum64(t)) {
+		struct btf_enum64 *e = btf_enum64(t);
+		int i, n = btf_vlen(t);
+
+		for (i = 0; i < n; ++i, ++e) {
+			const char *cur_name = btf__name_by_offset(btf, e->name_off);
+			__u64 value =  btf_enum64_value(e);
+
+			if (strcmp(cur_name, evalue) == 0) {
+				*retval = value;
+				return 0;
+			}
+		}
+	}
+	return -EINVAL;
+}
+
+static bool is_preset_supported(const struct btf_type *t)
+{
+	return btf_is_int(t) || btf_is_enum(t) || btf_is_enum64(t);
+}
+
+static int set_global_var(struct bpf_object *obj, struct btf *btf, const struct btf_type *t,
+			  struct bpf_map *map, struct btf_var_secinfo *sinfo,
+			  struct var_preset *preset)
+{
+	const struct btf_type *base_type;
+	void *ptr;
+	long long value = preset->ivalue;
+	size_t size;
+
+	base_type = btf__type_by_id(btf, btf__resolve_type(btf, t->type));
+	if (!base_type) {
+		fprintf(stderr, "Failed to resolve type %d\n", t->type);
+		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));
+		return -EINVAL;
+	}
+
+	if (preset->type == ENUMERATOR) {
+		if (btf_is_any_enum(base_type)) {
+			if (enum_value_from_name(btf, base_type, preset->svalue, &value)) {
+				fprintf(stderr,
+					"Failed to find integer value for enum element %s\n",
+					preset->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));
+			return -EINVAL;
+		}
+	}
+
+	/* Check if value fits into the target variable size */
+	if  (sinfo->size < sizeof(value)) {
+		bool is_signed = is_signed_type(base_type);
+		__u32 unsigned_bits = sinfo->size * 8 - (is_signed ? 1 : 0);
+		long long max_val = 1ll << unsigned_bits;
+
+		if (value >= max_val || value < -max_val) {
+			fprintf(stderr,
+				"Variable %s value %lld is out of range [%lld; %lld]\n",
+				btf__name_by_offset(btf, t->name_off), value,
+				is_signed ? -max_val : 0, max_val - 1);
+			return -EINVAL;
+		}
+	}
+
+	ptr = bpf_map__initial_value(map, &size);
+	if (!ptr || sinfo->offset + sinfo->size > size)
+		return -EINVAL;
+
+	if (__BYTE_ORDER == __LITTLE_ENDIAN) {
+		memcpy(ptr + sinfo->offset, &value, sinfo->size);
+	} else { /* __BYTE_ORDER == __BIG_ENDIAN */
+		__u8 src_offset = sizeof(value) - sinfo->size;
+
+		memcpy(ptr + sinfo->offset, (void *)&value + src_offset, sinfo->size);
+	}
+	return 0;
+}
+
+static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, int npresets)
+{
+	struct btf_var_secinfo *sinfo;
+	const char *sec_name;
+	const struct btf_type *t;
+	struct bpf_map *map;
+	struct btf *btf;
+	int i, j, k, n, cnt, err = 0;
+
+	if (npresets == 0)
+		return 0;
+
+	btf = bpf_object__btf(obj);
+	if (!btf)
+		return -EINVAL;
+
+	cnt = btf__type_cnt(btf);
+	for (i = 1; i != cnt; ++i) {
+		t = btf__type_by_id(btf, i);
+
+		if (!btf_is_datasec(t))
+			continue;
+
+		sinfo = btf_var_secinfos(t);
+		sec_name = btf__name_by_offset(btf, t->name_off);
+		map = bpf_object__find_map_by_name(obj, sec_name);
+		if (!map)
+			continue;
+
+		n = btf_vlen(t);
+		for (j = 0; j < n; ++j, ++sinfo) {
+			const struct btf_type *var_type = btf__type_by_id(btf, sinfo->type);
+			const char *var_name;
+
+			if (!btf_is_var(var_type))
+				continue;
+
+			var_name = btf__name_by_offset(btf, var_type->name_off);
+
+			for (k = 0; k < npresets; ++k) {
+				if (strcmp(var_name, presets[k].name) != 0)
+					continue;
+
+				if (presets[k].applied) {
+					fprintf(stderr, "Variable %s is set more than once",
+						var_name);
+					return -EINVAL;
+				}
+
+				err = set_global_var(obj, btf, var_type, map, sinfo, presets + k);
+				if (err)
+					return err;
+
+				presets[k].applied = true;
+				break;
+			}
+		}
+	}
+	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].applied = false;
+	}
+	return err;
+}
+
 static int process_obj(const char *filename)
 {
 	const char *base_filename = basename(strdupa(filename));
@@ -1341,6 +1623,11 @@ static int process_obj(const char *filename)
 	if (prog_cnt == 1) {
 		prog = bpf_object__next_program(obj, NULL);
 		bpf_program__set_autoload(prog, true);
+		err = set_global_vars(obj, env.presets, env.npresets);
+		if (err) {
+			fprintf(stderr, "Failed to set global variables %d\n", err);
+			goto cleanup;
+		}
 		process_prog(filename, obj, prog);
 		goto cleanup;
 	}
@@ -1355,6 +1642,12 @@ static int process_obj(const char *filename)
 			goto cleanup;
 		}
 
+		err = set_global_vars(tobj, env.presets, env.npresets);
+		if (err) {
+			fprintf(stderr, "Failed to set global variables %d\n", err);
+			goto cleanup;
+		}
+
 		lprog = NULL;
 		bpf_object__for_each_program(tprog, tobj) {
 			const char *tprog_name = bpf_program__name(tprog);
@@ -2460,5 +2753,11 @@ int main(int argc, char **argv)
 		free(env.deny_filters[i].prog_glob);
 	}
 	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);
 	return -err;
 }