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Mon, 10 Feb 2025 17:24:54 -0800 (PST) Message-ID: <5d89c59467645cbb6d9a38a4ab52c7f7e614ec48.camel@gmail.com> Subject: Re: [PATCH bpf-next v2 1/2] selftests/bpf: implement setting global variables in veristat From: Eduard Zingerman To: Mykyta Yatsenko , bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kafai@meta.com, kernel-team@meta.com Cc: Mykyta Yatsenko Date: Mon, 10 Feb 2025 17:24:48 -0800 In-Reply-To: <20250210135129.719119-2-mykyta.yatsenko5@gmail.com> References: <20250210135129.719119-1-mykyta.yatsenko5@gmail.com> <20250210135129.719119-2-mykyta.yatsenko5@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-02-10 at 13:51 +0000, Mykyta Yatsenko wrote: [...] > @@ -363,6 +378,24 @@ static error_t parse_arg(int key, char *arg, struct = argp_state *state) > return -ENOMEM; > env.filename_cnt++; > break; > + case 'G': { > + static int presets_cap; > + char *expr =3D strdup(arg); > + > + if (expr[0] =3D=3D '@') { > + if (parse_var_presets_from_file(expr + 1, &env.presets, > + &presets_cap, &env.npresets)) { Nit: I'd modify 'env' directly in parse_var_presets{,_from_file} and add presets_cap field to 'env': to avoid static variable and to avoid '(*presets)[*size].name =3D ...' below. > + fprintf(stderr, "Could not parse global variables preset: %s\n", > + arg); > + argp_usage(state); > + } > + } else if (parse_var_presets(expr, &env.presets, &presets_cap, &env.np= resets)) { > + fprintf(stderr, "Could not parse global variables preset: %s\n", arg)= ; > + argp_usage(state); > + } > + free(expr); > + break; > + } > default: > return ARGP_ERR_UNKNOWN; > } > @@ -1292,6 +1325,273 @@ static int process_prog(const char *filename, str= uct bpf_object *obj, struct bpf > return 0; > }; > =20 > +static int parse_var_presets(char *expr, struct var_preset **presets, in= t *capacity, int *size) > +{ > + char *eq_ptr =3D strchr(expr, '=3D'); > + char *name_ptr =3D expr; > + char *name_end =3D eq_ptr - 1; > + char *val_ptr =3D eq_ptr + 1; > + long long value; > + > + if (!eq_ptr) { > + fprintf(stderr, "No assignment in expression\n"); > + return -EINVAL; > + } > + > + while (isspace(*name_ptr)) > + ++name_ptr; > + while (isspace(*name_end)) > + --name_end; I think this loop has to be capped by string start check, otherwise for -G ' =3D 10' it might read some uninitialized memory. > + while (isspace(*val_ptr)) > + ++val_ptr; > + > + if (name_ptr > name_end) { > + fprintf(stderr, "Empty variable name in expression %s\n", expr); > + return -EINVAL; > + } > + > + if (*size >=3D *capacity) { > + *capacity =3D max(*capacity * 2, 1); > + *presets =3D realloc(*presets, *capacity * sizeof(**presets)); Nit: if realloc() fails it returns NULL, so the pointer to older *presets would be lost and never freed (but we exit the program in case of an error, so not really an issue). Also, check for NULL and return -ENOMEM? > + } > + > + if (isalpha(*val_ptr)) { > + char *value_end =3D val_ptr + strlen(val_ptr) - 1; > + > + while (isspace(*value_end)) > + --value_end; > + *(value_end + 1) =3D '\0'; > + > + (*presets)[*size].svalue =3D strdup(val_ptr); Silly question, why strdup here and for .name? Keeping pointers to argv should be fine as far as I know. > + (*presets)[*size].type =3D NAME; > + } else if (*val_ptr =3D=3D '-' || isdigit(*val_ptr)) { > + errno =3D 0; > + value =3D strtoll(val_ptr, NULL, 0); > + if (errno =3D=3D ERANGE) { > + errno =3D 0; > + value =3D strtoull(val_ptr, NULL, 0); > + } > + (*presets)[*size].ivalue =3D value; > + (*presets)[*size].type =3D INTEGRAL; > + if (errno) { > + fprintf(stderr, "Could not parse integer value %s\n", val_ptr); > + return -EINVAL; > + } > + } else { > + fprintf(stderr, "Could not parse value %s\n", val_ptr); > + return -EINVAL; > + } > + *(name_end + 1) =3D '\0'; > + (*presets)[*size].name =3D strdup(name_ptr); > + (*size)++; > + return 0; > +} > + > +static int parse_var_presets_from_file(const char *filename, struct var_= preset **presets, > + int *capacity, int *size) Thank you for adding this! > +{ > + FILE *f; > + char line[256]; > + int err =3D 0; > + > + f =3D fopen(filename, "rt"); > + if (!f) { > + fprintf(stderr, "Could not open file %s\n", filename); > + return -EINVAL; > + } > + > + while (fgets(line, sizeof(line), f)) { > + int err =3D parse_var_presets(line, presets, capacity, size); > + > + if (err) > + goto cleanup; > + } > + > +cleanup: Nit: I'd check for ferror(f) and write something to stderr here. > + 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_enum(t)) > + return btf_kflag(t); > + return true; > +} [...] > +static int set_global_vars(struct bpf_object *obj, struct var_preset *pr= esets, int npresets) > +{ > + struct btf_var_secinfo *sinfo; > + const char *sec_name; > + const struct btf_type *type; > + struct bpf_map *map; > + struct btf *btf; > + bool *set_var; > + int i, j, k, n, cnt, err =3D 0; > + > + if (npresets =3D=3D 0) > + return 0; > + > + btf =3D bpf_object__btf(obj); > + if (!btf) > + return -EINVAL; > + > + set_var =3D calloc(npresets, sizeof(bool)); > + for (i =3D 0; i < npresets; ++i) > + set_var[i] =3D false; As Andrii writes in a sibling thread, I'd keep this flag in the 'struct var_preset'. > + > + cnt =3D btf__type_cnt(btf); > + for (i =3D 0; i !=3D cnt; ++i) { > + type =3D btf__type_by_id(btf, i); > + > + if (!btf_is_datasec(type)) > + continue; > + > + sinfo =3D btf_var_secinfos(type); > + sec_name =3D btf__name_by_offset(btf, type->name_off); > + map =3D bpf_object__find_map_by_name(obj, sec_name); > + if (!map) > + continue; > + > + n =3D btf_vlen(type); > + for (j =3D 0; j < n; ++j, ++sinfo) { > + const struct btf_type *var_type =3D btf__type_by_id(btf, sinfo->type)= ; > + const char *var_name =3D btf__name_by_offset(btf, var_type->name_off)= ; > + > + if (!btf_is_var(var_type)) > + continue; > + > + for (k =3D 0; k < npresets; ++k) { > + if (strcmp(var_name, presets[k].name) !=3D 0) > + continue; > + > + if (set_var[k]) { > + fprintf(stderr, "Variable %s is set more than once", > + var_name); > + } > + > + err =3D set_global_var(obj, btf, var_type, map, sinfo, presets + k); > + if (err) > + goto out; > + > + set_var[k] =3D true; > + break; > + } > + } > + } > + for (i =3D 0; i < npresets; ++i) { > + if (!set_var[i]) { > + fprintf(stderr, "Global variable preset %s has not been applied\n", > + presets[i].name); > + } > + } > +out: > + free(set_var); > + return err; > +} > + [...]