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