tools/bpf/bpftool/gen.c

   1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
   2 /* Copyright (C) 2019 Facebook */
   3
   4 #ifndef _GNU_SOURCE
   5 #define _GNU_SOURCE
   6 #endif
   7 #include <ctype.h>
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <linux/err.h>
  11 #include <stdbool.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15 #include <bpf/bpf.h>
  16 #include <bpf/libbpf.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <sys/mman.h>
  20 #include <bpf/btf.h>
  21
  22 #include "json_writer.h"
  23 #include "main.h"
  24
  25 #define MAX_OBJ_NAME_LEN 64
  26
  27 static void sanitize_identifier(char *name)
  28 {
  29         int i;
  30
  31         for (i = 0; name[i]; i++)
  32                 if (!isalnum(name[i]) && name[i] != '_')
  33                         name[i] = '_';
  34 }
  35
  36 static bool str_has_suffix(const char *str, const char *suffix)
  37 {
  38         size_t i, n1 = strlen(str), n2 = strlen(suffix);
  39
  40         if (n1 < n2)
  41                 return false;
  42
  43         for (i = 0; i < n2; i++) {
  44                 if (str[n1 - i - 1] != suffix[n2 - i - 1])
  45                         return false;
  46         }
  47
  48         return true;
  49 }
  50
  51 static void get_obj_name(char *name, const char *file)
  52 {
  53         /* Using basename() GNU version which doesn't modify arg. */
  54         strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
  55         name[MAX_OBJ_NAME_LEN - 1] = '\0';
  56         if (str_has_suffix(name, ".o"))
  57                 name[strlen(name) - 2] = '\0';
  58         sanitize_identifier(name);
  59 }
  60
  61 static void get_header_guard(char *guard, const char *obj_name)
  62 {
  63         int i;
  64
  65         sprintf(guard, "__%s_SKEL_H__", obj_name);
  66         for (i = 0; guard[i]; i++)
  67                 guard[i] = toupper(guard[i]);
  68 }
  69
  70 static const char *get_map_ident(const struct bpf_map *map)
  71 {
  72         const char *name = bpf_map__name(map);
  73
  74         if (!bpf_map__is_internal(map))
  75                 return name;
  76
  77         if (str_has_suffix(name, ".data"))
  78                 return "data";
  79         else if (str_has_suffix(name, ".rodata"))
  80                 return "rodata";
  81         else if (str_has_suffix(name, ".bss"))
  82                 return "bss";
  83         else if (str_has_suffix(name, ".kconfig"))
  84                 return "kconfig";
  85         else
  86                 return NULL;
  87 }
  88
  89 static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
  90 {
  91         vprintf(fmt, args);
  92 }
  93
  94 static int codegen_datasec_def(struct bpf_object *obj,
  95                                struct btf *btf,
  96                                struct btf_dump *d,
  97                                const struct btf_type *sec,
  98                                const char *obj_name)
  99 {
 100         const char *sec_name = btf__name_by_offset(btf, sec->name_off);
 101         const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
 102         int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
 103         const char *sec_ident;
 104         char var_ident[256];
 105         bool strip_mods = false;
 106
 107         if (strcmp(sec_name, ".data") == 0) {
 108                 sec_ident = "data";
 109         } else if (strcmp(sec_name, ".bss") == 0) {
 110                 sec_ident = "bss";
 111         } else if (strcmp(sec_name, ".rodata") == 0) {
 112                 sec_ident = "rodata";
 113                 strip_mods = true;
 114         } else if (strcmp(sec_name, ".kconfig") == 0) {
 115                 sec_ident = "kconfig";
 116         } else {
 117                 return 0;
 118         }
 119
 120         printf("        struct %s__%s {\n", obj_name, sec_ident);
 121         for (i = 0; i < vlen; i++, sec_var++) {
 122                 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
 123                 const char *var_name = btf__name_by_offset(btf, var->name_off);
 124                 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
 125                         .field_name = var_ident,
 126                         .indent_level = 2,
 127                         .strip_mods = strip_mods,
 128                 );
 129                 int need_off = sec_var->offset, align_off, align;
 130                 __u32 var_type_id = var->type;
 131
 132                 if (off > need_off) {
 133                         p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
 134                               sec_name, i, need_off, off);
 135                         return -EINVAL;
 136                 }
 137
 138                 align = btf__align_of(btf, var->type);
 139                 if (align <= 0) {
 140                         p_err("Failed to determine alignment of variable '%s': %d",
 141                               var_name, align);
 142                         return -EINVAL;
 143                 }
 144                 /* Assume 32-bit architectures when generating data section
 145                  * struct memory layout. Given bpftool can't know which target
 146                  * host architecture it's emitting skeleton for, we need to be
 147                  * conservative and assume 32-bit one to ensure enough padding
 148                  * bytes are generated for pointer and long types. This will
 149                  * still work correctly for 64-bit architectures, because in
 150                  * the worst case we'll generate unnecessary padding field,
 151                  * which on 64-bit architectures is not strictly necessary and
 152                  * would be handled by natural 8-byte alignment. But it still
 153                  * will be a correct memory layout, based on recorded offsets
 154                  * in BTF.
 155                  */
 156                 if (align > 4)
 157                         align = 4;
 158
 159                 align_off = (off + align - 1) / align * align;
 160                 if (align_off != need_off) {
 161                         printf("\t\tchar __pad%d[%d];\n",
 162                                pad_cnt, need_off - off);
 163                         pad_cnt++;
 164                 }
 165
 166                 /* sanitize variable name, e.g., for static vars inside
 167                  * a function, it's name is '<function name>.<variable name>',
 168                  * which we'll turn into a '<function name>_<variable name>'
 169                  */
 170                 var_ident[0] = '\0';
 171                 strncat(var_ident, var_name, sizeof(var_ident) - 1);
 172                 sanitize_identifier(var_ident);
 173
 174                 printf("\t\t");
 175                 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
 176                 if (err)
 177                         return err;
 178                 printf(";\n");
 179
 180                 off = sec_var->offset + sec_var->size;
 181         }
 182         printf("        } *%s;\n", sec_ident);
 183         return 0;
 184 }
 185
 186 static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
 187 {
 188         struct btf *btf = bpf_object__btf(obj);
 189         int n = btf__get_nr_types(btf);
 190         struct btf_dump *d;
 191         int i, err = 0;
 192
 193         d = btf_dump__new(btf, NULL, NULL, codegen_btf_dump_printf);
 194         if (IS_ERR(d))
 195                 return PTR_ERR(d);
 196
 197         for (i = 1; i <= n; i++) {
 198                 const struct btf_type *t = btf__type_by_id(btf, i);
 199
 200                 if (!btf_is_datasec(t))
 201                         continue;
 202
 203                 err = codegen_datasec_def(obj, btf, d, t, obj_name);
 204                 if (err)
 205                         goto out;
 206         }
 207 out:
 208         btf_dump__free(d);
 209         return err;
 210 }
 211
 212 static void codegen(const char *template, ...)
 213 {
 214         const char *src, *end;
 215         int skip_tabs = 0, n;
 216         char *s, *dst;
 217         va_list args;
 218         char c;
 219
 220         n = strlen(template);
 221         s = malloc(n + 1);
 222         if (!s)
 223                 exit(-1);
 224         src = template;
 225         dst = s;
 226
 227         /* find out "baseline" indentation to skip */
 228         while ((c = *src++)) {
 229                 if (c == '\t') {
 230                         skip_tabs++;
 231                 } else if (c == '\n') {
 232                         break;
 233                 } else {
 234                         p_err("unrecognized character at pos %td in template '%s'",
 235                               src - template - 1, template);
 236                         free(s);
 237                         exit(-1);
 238                 }
 239         }
 240
 241         while (*src) {
 242                 /* skip baseline indentation tabs */
 243                 for (n = skip_tabs; n > 0; n--, src++) {
 244                         if (*src != '\t') {
 245                                 p_err("not enough tabs at pos %td in template '%s'",
 246                                       src - template - 1, template);
 247                                 free(s);
 248                                 exit(-1);
 249                         }
 250                 }
 251                 /* trim trailing whitespace */
 252                 end = strchrnul(src, '\n');
 253                 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
 254                         ;
 255                 memcpy(dst, src, n);
 256                 dst += n;
 257                 if (*end)
 258                         *dst++ = '\n';
 259                 src = *end ? end + 1 : end;
 260         }
 261         *dst++ = '\0';
 262
 263         /* print out using adjusted template */
 264         va_start(args, template);
 265         n = vprintf(s, args);
 266         va_end(args);
 267
 268         free(s);
 269 }
 270
 271 static int do_skeleton(int argc, char **argv)
 272 {
 273         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
 274         size_t i, map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
 275         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
 276         char obj_name[MAX_OBJ_NAME_LEN], *obj_data;
 277         struct bpf_object *obj = NULL;
 278         const char *file, *ident;
 279         struct bpf_program *prog;
 280         int fd, len, err = -1;
 281         struct bpf_map *map;
 282         struct btf *btf;
 283         struct stat st;
 284
 285         if (!REQ_ARGS(1)) {
 286                 usage();
 287                 return -1;
 288         }
 289         file = GET_ARG();
 290
 291         if (argc) {
 292                 p_err("extra unknown arguments");
 293                 return -1;
 294         }
 295
 296         if (stat(file, &st)) {
 297                 p_err("failed to stat() %s: %s", file, strerror(errno));
 298                 return -1;
 299         }
 300         file_sz = st.st_size;
 301         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
 302         fd = open(file, O_RDONLY);
 303         if (fd < 0) {
 304                 p_err("failed to open() %s: %s", file, strerror(errno));
 305                 return -1;
 306         }
 307         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
 308         if (obj_data == MAP_FAILED) {
 309                 obj_data = NULL;
 310                 p_err("failed to mmap() %s: %s", file, strerror(errno));
 311                 goto out;
 312         }
 313         get_obj_name(obj_name, file);
 314         opts.object_name = obj_name;
 315         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 316         if (IS_ERR(obj)) {
 317                 char err_buf[256];
 318
 319                 libbpf_strerror(PTR_ERR(obj), err_buf, sizeof(err_buf));
 320                 p_err("failed to open BPF object file: %s", err_buf);
 321                 obj = NULL;
 322                 goto out;
 323         }
 324
 325         bpf_object__for_each_map(map, obj) {
 326                 ident = get_map_ident(map);
 327                 if (!ident) {
 328                         p_err("ignoring unrecognized internal map '%s'...",
 329                               bpf_map__name(map));
 330                         continue;
 331                 }
 332                 map_cnt++;
 333         }
 334         bpf_object__for_each_program(prog, obj) {
 335                 prog_cnt++;
 336         }
 337
 338         get_header_guard(header_guard, obj_name);
 339         codegen("\
 340                 \n\
 341                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
 342                                                                             \n\
 343                 /* THIS FILE IS AUTOGENERATED! */                           \n\
 344                 #ifndef %2$s                                                \n\
 345                 #define %2$s                                                \n\
 346                                                                             \n\
 347                 #include <stdlib.h>                                         \n\
 348                 #include <bpf/libbpf.h>                                     \n\
 349                                                                             \n\
 350                 struct %1$s {                                               \n\
 351                         struct bpf_object_skeleton *skeleton;               \n\
 352                         struct bpf_object *obj;                             \n\
 353                 ",
 354                 obj_name, header_guard
 355         );
 356
 357         if (map_cnt) {
 358                 printf("\tstruct {\n");
 359                 bpf_object__for_each_map(map, obj) {
 360                         ident = get_map_ident(map);
 361                         if (!ident)
 362                                 continue;
 363                         printf("\t\tstruct bpf_map *%s;\n", ident);
 364                 }
 365                 printf("\t} maps;\n");
 366         }
 367
 368         if (prog_cnt) {
 369                 printf("\tstruct {\n");
 370                 bpf_object__for_each_program(prog, obj) {
 371                         printf("\t\tstruct bpf_program *%s;\n",
 372                                bpf_program__name(prog));
 373                 }
 374                 printf("\t} progs;\n");
 375                 printf("\tstruct {\n");
 376                 bpf_object__for_each_program(prog, obj) {
 377                         printf("\t\tstruct bpf_link *%s;\n",
 378                                bpf_program__name(prog));
 379                 }
 380                 printf("\t} links;\n");
 381         }
 382
 383         btf = bpf_object__btf(obj);
 384         if (btf) {
 385                 err = codegen_datasecs(obj, obj_name);
 386                 if (err)
 387                         goto out;
 388         }
 389
 390         codegen("\
 391                 \n\
 392                 };                                                          \n\
 393                                                                             \n\
 394                 static void                                                 \n\
 395                 %1$s__destroy(struct %1$s *obj)                             \n\
 396                 {                                                           \n\
 397                         if (!obj)                                           \n\
 398                                 return;                                     \n\
 399                         if (obj->skeleton)                                  \n\
 400                                 bpf_object__destroy_skeleton(obj->skeleton);\n\
 401                         free(obj);                                          \n\
 402                 }                                                           \n\
 403                                                                             \n\
 404                 static inline int                                           \n\
 405                 %1$s__create_skeleton(struct %1$s *obj);                    \n\
 406                                                                             \n\
 407                 static inline struct %1$s *                                 \n\
 408                 %1$s__open_opts(const struct bpf_object_open_opts *opts)    \n\
 409                 {                                                           \n\
 410                         struct %1$s *obj;                                   \n\
 411                                                                             \n\
 412                         obj = (struct %1$s *)calloc(1, sizeof(*obj));       \n\
 413                         if (!obj)                                           \n\
 414                                 return NULL;                                \n\
 415                         if (%1$s__create_skeleton(obj))                     \n\
 416                                 goto err;                                   \n\
 417                         if (bpf_object__open_skeleton(obj->skeleton, opts)) \n\
 418                                 goto err;                                   \n\
 419                                                                             \n\
 420                         return obj;                                         \n\
 421                 err:                                                        \n\
 422                         %1$s__destroy(obj);                                 \n\
 423                         return NULL;                                        \n\
 424                 }                                                           \n\
 425                                                                             \n\
 426                 static inline struct %1$s *                                 \n\
 427                 %1$s__open(void)                                            \n\
 428                 {                                                           \n\
 429                         return %1$s__open_opts(NULL);                       \n\
 430                 }                                                           \n\
 431                                                                             \n\
 432                 static inline int                                           \n\
 433                 %1$s__load(struct %1$s *obj)                                \n\
 434                 {                                                           \n\
 435                         return bpf_object__load_skeleton(obj->skeleton);    \n\
 436                 }                                                           \n\
 437                                                                             \n\
 438                 static inline struct %1$s *                                 \n\
 439                 %1$s__open_and_load(void)                                   \n\
 440                 {                                                           \n\
 441                         struct %1$s *obj;                                   \n\
 442                                                                             \n\
 443                         obj = %1$s__open();                                 \n\
 444                         if (!obj)                                           \n\
 445                                 return NULL;                                \n\
 446                         if (%1$s__load(obj)) {                              \n\
 447                                 %1$s__destroy(obj);                         \n\
 448                                 return NULL;                                \n\
 449                         }                                                   \n\
 450                         return obj;                                         \n\
 451                 }                                                           \n\
 452                                                                             \n\
 453                 static inline int                                           \n\
 454                 %1$s__attach(struct %1$s *obj)                              \n\
 455                 {                                                           \n\
 456                         return bpf_object__attach_skeleton(obj->skeleton);  \n\
 457                 }                                                           \n\
 458                                                                             \n\
 459                 static inline void                                          \n\
 460                 %1$s__detach(struct %1$s *obj)                              \n\
 461                 {                                                           \n\
 462                         return bpf_object__detach_skeleton(obj->skeleton);  \n\
 463                 }                                                           \n\
 464                 ",
 465                 obj_name
 466         );
 467
 468         codegen("\
 469                 \n\
 470                                                                             \n\
 471                 static inline int                                           \n\
 472                 %1$s__create_skeleton(struct %1$s *obj)                     \n\
 473                 {                                                           \n\
 474                         struct bpf_object_skeleton *s;                      \n\
 475                                                                             \n\
 476                         s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
 477                         if (!s)                                             \n\
 478                                 return -1;                                  \n\
 479                         obj->skeleton = s;                                  \n\
 480                                                                             \n\
 481                         s->sz = sizeof(*s);                                 \n\
 482                         s->name = \"%1$s\";                                 \n\
 483                         s->obj = &obj->obj;                                 \n\
 484                 ",
 485                 obj_name
 486         );
 487         if (map_cnt) {
 488                 codegen("\
 489                         \n\
 490                                                                             \n\
 491                                 /* maps */                                  \n\
 492                                 s->map_cnt = %zu;                           \n\
 493                                 s->map_skel_sz = sizeof(*s->maps);          \n\
 494                                 s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
 495                                 if (!s->maps)                               \n\
 496                                         goto err;                           \n\
 497                         ",
 498                         map_cnt
 499                 );
 500                 i = 0;
 501                 bpf_object__for_each_map(map, obj) {
 502                         ident = get_map_ident(map);
 503
 504                         if (!ident)
 505                                 continue;
 506
 507                         codegen("\
 508                                 \n\
 509                                                                             \n\
 510                                         s->maps[%zu].name = \"%s\";         \n\
 511                                         s->maps[%zu].map = &obj->maps.%s;   \n\
 512                                 ",
 513                                 i, bpf_map__name(map), i, ident);
 514                         /* memory-mapped internal maps */
 515                         if (bpf_map__is_internal(map) &&
 516                             (bpf_map__def(map)->map_flags & BPF_F_MMAPABLE)) {
 517                                 printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
 518                                        i, ident);
 519                         }
 520                         i++;
 521                 }
 522         }
 523         if (prog_cnt) {
 524                 codegen("\
 525                         \n\
 526                                                                             \n\
 527                                 /* programs */                              \n\
 528                                 s->prog_cnt = %zu;                          \n\
 529                                 s->prog_skel_sz = sizeof(*s->progs);        \n\
 530                                 s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
 531                                 if (!s->progs)                              \n\
 532                                         goto err;                           \n\
 533                         ",
 534                         prog_cnt
 535                 );
 536                 i = 0;
 537                 bpf_object__for_each_program(prog, obj) {
 538                         codegen("\
 539                                 \n\
 540                                                                             \n\
 541                                         s->progs[%1$zu].name = \"%2$s\";    \n\
 542                                         s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
 543                                         s->progs[%1$zu].link = &obj->links.%2$s;\n\
 544                                 ",
 545                                 i, bpf_program__name(prog));
 546                         i++;
 547                 }
 548         }
 549         codegen("\
 550                 \n\
 551                                                                             \n\
 552                         s->data_sz = %d;                                    \n\
 553                         s->data = (void *)\"\\                              \n\
 554                 ",
 555                 file_sz);
 556
 557         /* embed contents of BPF object file */
 558         for (i = 0, len = 0; i < file_sz; i++) {
 559                 int w = obj_data[i] ? 4 : 2;
 560
 561                 len += w;
 562                 if (len > 78) {
 563                         printf("\\\n");
 564                         len = w;
 565                 }
 566                 if (!obj_data[i])
 567                         printf("\\0");
 568                 else
 569                         printf("\\x%02x", (unsigned char)obj_data[i]);
 570         }
 571
 572         codegen("\
 573                 \n\
 574                 \";                                                         \n\
 575                                                                             \n\
 576                         return 0;                                           \n\
 577                 err:                                                        \n\
 578                         bpf_object__destroy_skeleton(s);                    \n\
 579                         return -1;                                          \n\
 580                 }                                                           \n\
 581                                                                             \n\
 582                 #endif /* %s */                                             \n\
 583                 ",
 584                 header_guard);
 585         err = 0;
 586 out:
 587         bpf_object__close(obj);
 588         if (obj_data)
 589                 munmap(obj_data, mmap_sz);
 590         close(fd);
 591         return err;
 592 }
 593
 594 static int do_help(int argc, char **argv)
 595 {
 596         if (json_output) {
 597                 jsonw_null(json_wtr);
 598                 return 0;
 599         }
 600
 601         fprintf(stderr,
 602                 "Usage: %1$s %2$s skeleton FILE\n"
 603                 "       %1$s %2$s help\n"
 604                 "\n"
 605                 "       " HELP_SPEC_OPTIONS "\n"
 606                 "",
 607                 bin_name, "gen");
 608
 609         return 0;
 610 }
 611
 612 static const struct cmd cmds[] = {
 613         { "skeleton",   do_skeleton },
 614         { "help",       do_help },
 615         { 0 }
 616 };
 617
 618 int do_gen(int argc, char **argv)
 619 {
 620         return cmd_select(cmds, argc, argv, do_help);
 621 }