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[86.26.115.213]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f259d9be9sm24880003f8f.79.2025.02.21.14.33.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Feb 2025 14:33:05 -0800 (PST) From: Mykyta Yatsenko To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kafai@meta.com, kernel-team@meta.com, eddyz87@gmail.com Cc: Mykyta Yatsenko Subject: [PATCH bpf-next v4 1/2] selftests/bpf: implement setting global variables in veristat Date: Fri, 21 Feb 2025 22:32:58 +0000 Message-ID: <20250221223259.677471-2-mykyta.yatsenko5@gmail.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250221223259.677471-1-mykyta.yatsenko5@gmail.com> References: <20250221223259.677471-1-mykyta.yatsenko5@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Mykyta Yatsenko To better verify some complex BPF programs we'd like to preset global variables. This patch introduces CLI argument `--set-global-vars` or `-G` to veristat, that allows presetting values to global variables defined in BPF program. For example: prog.c: ``` enum Enum { ELEMENT1 = 0, ELEMENT2 = 5 }; const volatile __s64 a = 5; const volatile __u8 b = 5; const volatile enum Enum c = ELEMENT2; const volatile bool d = false; char arr[4] = {0}; SEC("tp_btf/sched_switch") int BPF_PROG(...) { bpf_printk("%c\n", arr[a]); bpf_printk("%c\n", arr[b]); bpf_printk("%c\n", arr[c]); bpf_printk("%c\n", arr[d]); return 0; } ``` By default verification of the program fails: ``` ./veristat prog.bpf.o ``` By presetting global variables, we can make verification pass: ``` ./veristat wq.bpf.o -G "a = 0" -G "b = 1" -G "c = 2" -G "d = 3" ``` Signed-off-by: Mykyta Yatsenko --- tools/testing/selftests/bpf/veristat.c | 290 ++++++++++++++++++++++++- 1 file changed, 289 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c index 06af5029885b..1e1bc0dfa50a 100644 --- a/tools/testing/selftests/bpf/veristat.c +++ b/tools/testing/selftests/bpf/veristat.c @@ -154,6 +154,16 @@ struct filter { bool abs; }; +struct var_preset { + char *name; + enum { INTEGRAL, NAME } type; + union { + long long ivalue; + char *svalue; + }; + bool applied; +}; + static struct env { char **filenames; int filename_cnt; @@ -195,6 +205,8 @@ 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 +258,15 @@ 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', "GLOBALS", 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) { @@ -363,6 +378,19 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state) return -ENOMEM; env.filename_cnt++; break; + case 'G': { + if (arg[0] == '@') { + if (append_var_preset_file(arg + 1)) { + fprintf(stderr, "Could not parse global variables preset: %s\n", + arg); + argp_usage(state); + } + } else if (append_var_preset(&env.presets, &env.npresets, arg)) { + fprintf(stderr, "Could not parse global variables preset: %s\n", arg); + argp_usage(state); + } + break; + } default: return ARGP_ERR_UNKNOWN; } @@ -632,7 +660,7 @@ 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 +1320,249 @@ 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]; + + tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets)); + if (!tmp) + return -ENOMEM; + *presets = tmp; + cur = &(*presets)[*cnt]; + cur->applied = false; + + if (sscanf(expr, "%s = %s\n", var, val) != 2) { + fprintf(stderr, "Could not parse expression %s\n", expr); + return -EINVAL; + } + + if (isalpha(*val)) { + cur->svalue = strdup(val); + cur->type = NAME; + } else if (*val == '-' || isdigit(*val)) { + long long value; + + errno = 0; + value = strtoll(val, NULL, 0); + if (errno == ERANGE) { + errno = 0; + value = strtoull(val, NULL, 0); + } + cur->ivalue = value; + cur->type = INTEGRAL; + if (errno) { + fprintf(stderr, "Could not parse integer value %s\n", val); + return -EINVAL; + } + } else { + fprintf(stderr, "Could not parse value %s\n", val); + return -EINVAL; + } + cur->name = strdup(var); + (*cnt)++; + 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, "Could not resolve type %d\n", t->type); + return -EINVAL; + } + if (!is_preset_supported(base_type)) { + fprintf(stderr, "Setting global variable for btf kind %d is not supported\n", + btf_kind(base_type)); + return -EINVAL; + } + + if (preset->type == NAME && btf_is_any_enum(base_type)) { + if (enum_value_from_name(btf, base_type, preset->svalue, &value) != 0) { + fprintf(stderr, "Could not find integer value for enum element %s\n", + preset->svalue); + 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 = (void *)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 if (__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 +1612,11 @@ 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\n"); + goto cleanup; + } process_prog(filename, obj, prog); goto cleanup; } @@ -1355,6 +1631,12 @@ 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\n"); + goto cleanup; + } + lprog = NULL; bpf_object__for_each_program(tprog, tobj) { const char *tprog_name = bpf_program__name(tprog); @@ -2460,5 +2742,11 @@ 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 == NAME) + free(env.presets[i].svalue); + } + free(env.presets); return -err; }