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                         free(s);
 228                         return -EINVAL;
 229                 }
 230         }
 231
 232         while (*src) {
 233                 /* skip baseline indentation tabs */
 234                 for (n = skip_tabs; n > 0; n--, src++) {
 235                         if (*src != '\t') {
 236                                 p_err("not enough tabs at pos %td in template '%s'",
 237                                       src - template - 1, template);
 238                                 free(s);
 239                                 return -EINVAL;
 240                         }
 241                 }
 242                 /* trim trailing whitespace */
 243                 end = strchrnul(src, '\n');
 244                 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
 245                         ;
 246                 memcpy(dst, src, n);
 247                 dst += n;
 248                 if (*end)
 249                         *dst++ = '\n';
 250                 src = *end ? end + 1 : end;
 251         }
 252         *dst++ = '\0';
 253
 254         /* print out using adjusted template */
 255         va_start(args, template);
 256         n = vprintf(s, args);
 257         va_end(args);
 258
 259         free(s);
 260         return n;
 261 }
 262
 263 static int do_skeleton(int argc, char **argv)
 264 {
 265         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
 266         size_t i, map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
 267         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
 268         char obj_name[MAX_OBJ_NAME_LEN], *obj_data;
 269         struct bpf_object *obj = NULL;
 270         const char *file, *ident;
 271         struct bpf_program *prog;
 272         int fd, len, err = -1;
 273         struct bpf_map *map;
 274         struct btf *btf;
 275         struct stat st;
 276
 277         if (!REQ_ARGS(1)) {
 278                 usage();
 279                 return -1;
 280         }
 281         file = GET_ARG();
 282
 283         if (argc) {
 284                 p_err("extra unknown arguments");
 285                 return -1;
 286         }
 287
 288         if (stat(file, &st)) {
 289                 p_err("failed to stat() %s: %s", file, strerror(errno));
 290                 return -1;
 291         }
 292         file_sz = st.st_size;
 293         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
 294         fd = open(file, O_RDONLY);
 295         if (fd < 0) {
 296                 p_err("failed to open() %s: %s", file, strerror(errno));
 297                 return -1;
 298         }
 299         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
 300         if (obj_data == MAP_FAILED) {
 301                 obj_data = NULL;
 302                 p_err("failed to mmap() %s: %s", file, strerror(errno));
 303                 goto out;
 304         }
 305         get_obj_name(obj_name, file);
 306         opts.object_name = obj_name;
 307         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 308         if (IS_ERR(obj)) {
 309                 obj = NULL;
 310                 p_err("failed to open BPF object file: %ld", PTR_ERR(obj));
 311                 goto out;
 312         }
 313
 314         bpf_object__for_each_map(map, obj) {
 315                 ident = get_map_ident(map);
 316                 if (!ident) {
 317                         p_err("ignoring unrecognized internal map '%s'...",
 318                               bpf_map__name(map));
 319                         continue;
 320                 }
 321                 map_cnt++;
 322         }
 323         bpf_object__for_each_program(prog, obj) {
 324                 prog_cnt++;
 325         }
 326
 327         get_header_guard(header_guard, obj_name);
 328         codegen("\
 329                 \n\
 330                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
 331                                                                             \n\
 332                 /* THIS FILE IS AUTOGENERATED! */                           \n\
 333                 #ifndef %2$s                                                \n\
 334                 #define %2$s                                                \n\
 335                                                                             \n\
 336                 #include <stdlib.h>                                         \n\
 337                 #include <bpf/libbpf.h>                                     \n\
 338                                                                             \n\
 339                 struct %1$s {                                               \n\
 340                         struct bpf_object_skeleton *skeleton;               \n\
 341                         struct bpf_object *obj;                             \n\
 342                 ",
 343                 obj_name, header_guard
 344         );
 345
 346         if (map_cnt) {
 347                 printf("\tstruct {\n");
 348                 bpf_object__for_each_map(map, obj) {
 349                         ident = get_map_ident(map);
 350                         if (!ident)
 351                                 continue;
 352                         printf("\t\tstruct bpf_map *%s;\n", ident);
 353                 }
 354                 printf("\t} maps;\n");
 355         }
 356
 357         if (prog_cnt) {
 358                 printf("\tstruct {\n");
 359                 bpf_object__for_each_program(prog, obj) {
 360                         printf("\t\tstruct bpf_program *%s;\n",
 361                                bpf_program__name(prog));
 362                 }
 363                 printf("\t} progs;\n");
 364                 printf("\tstruct {\n");
 365                 bpf_object__for_each_program(prog, obj) {
 366                         printf("\t\tstruct bpf_link *%s;\n",
 367                                bpf_program__name(prog));
 368                 }
 369                 printf("\t} links;\n");
 370         }
 371
 372         btf = bpf_object__btf(obj);
 373         if (btf) {
 374                 err = codegen_datasecs(obj, obj_name);
 375                 if (err)
 376                         goto out;
 377         }
 378
 379         codegen("\
 380                 \n\
 381                 };                                                          \n\
 382                                                                             \n\
 383                 static void                                                 \n\
 384                 %1$s__destroy(struct %1$s *obj)                             \n\
 385                 {                                                           \n\
 386                         if (!obj)                                           \n\
 387                                 return;                                     \n\
 388                         if (obj->skeleton)                                  \n\
 389                                 bpf_object__destroy_skeleton(obj->skeleton);\n\
 390                         free(obj);                                          \n\
 391                 }                                                           \n\
 392                                                                             \n\
 393                 static inline int                                           \n\
 394                 %1$s__create_skeleton(struct %1$s *obj);                    \n\
 395                                                                             \n\
 396                 static inline struct %1$s *                                 \n\
 397                 %1$s__open_opts(const struct bpf_object_open_opts *opts)    \n\
 398                 {                                                           \n\
 399                         struct %1$s *obj;                                   \n\
 400                                                                             \n\
 401                         obj = (typeof(obj))calloc(1, sizeof(*obj));         \n\
 402                         if (!obj)                                           \n\
 403                                 return NULL;                                \n\
 404                         if (%1$s__create_skeleton(obj))                     \n\
 405                                 goto err;                                   \n\
 406                         if (bpf_object__open_skeleton(obj->skeleton, opts)) \n\
 407                                 goto err;                                   \n\
 408                                                                             \n\
 409                         return obj;                                         \n\
 410                 err:                                                        \n\
 411                         %1$s__destroy(obj);                                 \n\
 412                         return NULL;                                        \n\
 413                 }                                                           \n\
 414                                                                             \n\
 415                 static inline struct %1$s *                                 \n\
 416                 %1$s__open(void)                                            \n\
 417                 {                                                           \n\
 418                         return %1$s__open_opts(NULL);                       \n\
 419                 }                                                           \n\
 420                                                                             \n\
 421                 static inline int                                           \n\
 422                 %1$s__load(struct %1$s *obj)                                \n\
 423                 {                                                           \n\
 424                         return bpf_object__load_skeleton(obj->skeleton);    \n\
 425                 }                                                           \n\
 426                                                                             \n\
 427                 static inline struct %1$s *                                 \n\
 428                 %1$s__open_and_load(void)                                   \n\
 429                 {                                                           \n\
 430                         struct %1$s *obj;                                   \n\
 431                                                                             \n\
 432                         obj = %1$s__open();                                 \n\
 433                         if (!obj)                                           \n\
 434                                 return NULL;                                \n\
 435                         if (%1$s__load(obj)) {                              \n\
 436                                 %1$s__destroy(obj);                         \n\
 437                                 return NULL;                                \n\
 438                         }                                                   \n\
 439                         return obj;                                         \n\
 440                 }                                                           \n\
 441                                                                             \n\
 442                 static inline int                                           \n\
 443                 %1$s__attach(struct %1$s *obj)                              \n\
 444                 {                                                           \n\
 445                         return bpf_object__attach_skeleton(obj->skeleton);  \n\
 446                 }                                                           \n\
 447                                                                             \n\
 448                 static inline void                                          \n\
 449                 %1$s__detach(struct %1$s *obj)                              \n\
 450                 {                                                           \n\
 451                         return bpf_object__detach_skeleton(obj->skeleton);  \n\
 452                 }                                                           \n\
 453                 ",
 454                 obj_name
 455         );
 456
 457         codegen("\
 458                 \n\
 459                                                                             \n\
 460                 static inline int                                           \n\
 461                 %1$s__create_skeleton(struct %1$s *obj)                     \n\
 462                 {                                                           \n\
 463                         struct bpf_object_skeleton *s;                      \n\
 464                                                                             \n\
 465                         s = (typeof(s))calloc(1, sizeof(*s));               \n\
 466                         if (!s)                                             \n\
 467                                 return -1;                                  \n\
 468                         obj->skeleton = s;                                  \n\
 469                                                                             \n\
 470                         s->sz = sizeof(*s);                                 \n\
 471                         s->name = \"%1$s\";                                 \n\
 472                         s->obj = &obj->obj;                                 \n\
 473                 ",
 474                 obj_name
 475         );
 476         if (map_cnt) {
 477                 codegen("\
 478                         \n\
 479                                                                             \n\
 480                                 /* maps */                                  \n\
 481                                 s->map_cnt = %zu;                           \n\
 482                                 s->map_skel_sz = sizeof(*s->maps);          \n\
 483                                 s->maps = (typeof(s->maps))calloc(s->map_cnt, s->map_skel_sz);\n\
 484                                 if (!s->maps)                               \n\
 485                                         goto err;                           \n\
 486                         ",
 487                         map_cnt
 488                 );
 489                 i = 0;
 490                 bpf_object__for_each_map(map, obj) {
 491                         ident = get_map_ident(map);
 492
 493                         if (!ident)
 494                                 continue;
 495
 496                         codegen("\
 497                                 \n\
 498                                                                             \n\
 499                                         s->maps[%zu].name = \"%s\";         \n\
 500                                         s->maps[%zu].map = &obj->maps.%s;   \n\
 501                                 ",
 502                                 i, bpf_map__name(map), i, ident);
 503                         /* memory-mapped internal maps */
 504                         if (bpf_map__is_internal(map) &&
 505                             (bpf_map__def(map)->map_flags & BPF_F_MMAPABLE)) {
 506                                 printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
 507                                        i, ident);
 508                         }
 509                         i++;
 510                 }
 511         }
 512         if (prog_cnt) {
 513                 codegen("\
 514                         \n\
 515                                                                             \n\
 516                                 /* programs */                              \n\
 517                                 s->prog_cnt = %zu;                          \n\
 518                                 s->prog_skel_sz = sizeof(*s->progs);        \n\
 519                                 s->progs = (typeof(s->progs))calloc(s->prog_cnt, s->prog_skel_sz);\n\
 520                                 if (!s->progs)                              \n\
 521                                         goto err;                           \n\
 522                         ",
 523                         prog_cnt
 524                 );
 525                 i = 0;
 526                 bpf_object__for_each_program(prog, obj) {
 527                         codegen("\
 528                                 \n\
 529                                                                             \n\
 530                                         s->progs[%1$zu].name = \"%2$s\";    \n\
 531                                         s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
 532                                         s->progs[%1$zu].link = &obj->links.%2$s;\n\
 533                                 ",
 534                                 i, bpf_program__name(prog));
 535                         i++;
 536                 }
 537         }
 538         codegen("\
 539                 \n\
 540                                                                             \n\
 541                         s->data_sz = %d;                                    \n\
 542                         s->data = (void *)\"\\                              \n\
 543                 ",
 544                 file_sz);
 545
 546         /* embed contents of BPF object file */
 547         for (i = 0, len = 0; i < file_sz; i++) {
 548                 int w = obj_data[i] ? 4 : 2;
 549
 550                 len += w;
 551                 if (len > 78) {
 552                         printf("\\\n");
 553                         len = w;
 554                 }
 555                 if (!obj_data[i])
 556                         printf("\\0");
 557                 else
 558                         printf("\\x%02x", (unsigned char)obj_data[i]);
 559         }
 560
 561         codegen("\
 562                 \n\
 563                 \";                                                         \n\
 564                                                                             \n\
 565                         return 0;                                           \n\
 566                 err:                                                        \n\
 567                         bpf_object__destroy_skeleton(s);                    \n\
 568                         return -1;                                          \n\
 569                 }                                                           \n\
 570                                                                             \n\
 571                 #endif /* %s */                                             \n\
 572                 ",
 573                 header_guard);
 574         err = 0;
 575 out:
 576         bpf_object__close(obj);
 577         if (obj_data)
 578                 munmap(obj_data, mmap_sz);
 579         close(fd);
 580         return err;
 581 }
 582
 583 static int do_help(int argc, char **argv)
 584 {
 585         if (json_output) {
 586                 jsonw_null(json_wtr);
 587                 return 0;
 588         }
 589
 590         fprintf(stderr,
 591                 "Usage: %1$s %2$s skeleton FILE\n"
 592                 "       %1$s %2$s help\n"
 593                 "\n"
 594                 "       " HELP_SPEC_OPTIONS "\n"
 595                 "",
 596                 bin_name, "gen");
 597
 598         return 0;
 599 }
 600
 601 static const struct cmd cmds[] = {
 602         { "skeleton",   do_skeleton },
 603         { "help",       do_help },
 604         { 0 }
 605 };
 606
 607 int do_gen(int argc, char **argv)
 608 {
 609         return cmd_select(cmds, argc, argv, do_help);
 610 }