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 *ctx, 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         bool strip_mods = false;
 108
 109         if (strcmp(sec_name, ".data") == 0) {
 110                 sec_ident = "data";
 111         } else if (strcmp(sec_name, ".bss") == 0) {
 112                 sec_ident = "bss";
 113         } else if (strcmp(sec_name, ".rodata") == 0) {
 114                 sec_ident = "rodata";
 115                 strip_mods = true;
 116         } else if (strcmp(sec_name, ".kconfig") == 0) {
 117                 sec_ident = "kconfig";
 118         } else {
 119                 return 0;
 120         }
 121
 122         printf("        struct %s__%s {\n", obj_name, sec_ident);
 123         for (i = 0; i < vlen; i++, sec_var++) {
 124                 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
 125                 const char *var_name = btf__name_by_offset(btf, var->name_off);
 126                 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
 127                         .field_name = var_ident,
 128                         .indent_level = 2,
 129                         .strip_mods = strip_mods,
 130                 );
 131                 int need_off = sec_var->offset, align_off, align;
 132                 __u32 var_type_id = var->type;
 133
 134                 if (off > need_off) {
 135                         p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
 136                               sec_name, i, need_off, off);
 137                         return -EINVAL;
 138                 }
 139
 140                 align = btf__align_of(btf, var->type);
 141                 if (align <= 0) {
 142                         p_err("Failed to determine alignment of variable '%s': %d",
 143                               var_name, align);
 144                         return -EINVAL;
 145                 }
 146
 147                 align_off = (off + align - 1) / align * align;
 148                 if (align_off != need_off) {
 149                         printf("\t\tchar __pad%d[%d];\n",
 150                                pad_cnt, need_off - off);
 151                         pad_cnt++;
 152                 }
 153
 154                 /* sanitize variable name, e.g., for static vars inside
 155                  * a function, it's name is '<function name>.<variable name>',
 156                  * which we'll turn into a '<function name>_<variable name>'
 157                  */
 158                 var_ident[0] = '\0';
 159                 strncat(var_ident, var_name, sizeof(var_ident) - 1);
 160                 sanitize_identifier(var_ident);
 161
 162                 printf("\t\t");
 163                 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
 164                 if (err)
 165                         return err;
 166                 printf(";\n");
 167
 168                 off = sec_var->offset + sec_var->size;
 169         }
 170         printf("        } *%s;\n", sec_ident);
 171         return 0;
 172 }
 173
 174 static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
 175 {
 176         struct btf *btf = bpf_object__btf(obj);
 177         int n = btf__get_nr_types(btf);
 178         struct btf_dump *d;
 179         int i, err = 0;
 180
 181         d = btf_dump__new(btf, NULL, NULL, codegen_btf_dump_printf);
 182         if (IS_ERR(d))
 183                 return PTR_ERR(d);
 184
 185         for (i = 1; i <= n; i++) {
 186                 const struct btf_type *t = btf__type_by_id(btf, i);
 187
 188                 if (!btf_is_datasec(t))
 189                         continue;
 190
 191                 err = codegen_datasec_def(obj, btf, d, t, obj_name);
 192                 if (err)
 193                         goto out;
 194         }
 195 out:
 196         btf_dump__free(d);
 197         return err;
 198 }
 199
 200 static void codegen(const char *template, ...)
 201 {
 202         const char *src, *end;
 203         int skip_tabs = 0, n;
 204         char *s, *dst;
 205         va_list args;
 206         char c;
 207
 208         n = strlen(template);
 209         s = malloc(n + 1);
 210         if (!s)
 211                 exit(-1);
 212         src = template;
 213         dst = s;
 214
 215         /* find out "baseline" indentation to skip */
 216         while ((c = *src++)) {
 217                 if (c == '\t') {
 218                         skip_tabs++;
 219                 } else if (c == '\n') {
 220                         break;
 221                 } else {
 222                         p_err("unrecognized character at pos %td in template '%s'",
 223                               src - template - 1, template);
 224                         free(s);
 225                         exit(-1);
 226                 }
 227         }
 228
 229         while (*src) {
 230                 /* skip baseline indentation tabs */
 231                 for (n = skip_tabs; n > 0; n--, src++) {
 232                         if (*src != '\t') {
 233                                 p_err("not enough tabs at pos %td in template '%s'",
 234                                       src - template - 1, template);
 235                                 free(s);
 236                                 exit(-1);
 237                         }
 238                 }
 239                 /* trim trailing whitespace */
 240                 end = strchrnul(src, '\n');
 241                 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
 242                         ;
 243                 memcpy(dst, src, n);
 244                 dst += n;
 245                 if (*end)
 246                         *dst++ = '\n';
 247                 src = *end ? end + 1 : end;
 248         }
 249         *dst++ = '\0';
 250
 251         /* print out using adjusted template */
 252         va_start(args, template);
 253         n = vprintf(s, args);
 254         va_end(args);
 255
 256         free(s);
 257 }
 258
 259 static int do_skeleton(int argc, char **argv)
 260 {
 261         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
 262         size_t i, map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
 263         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
 264         char obj_name[MAX_OBJ_NAME_LEN], *obj_data;
 265         struct bpf_object *obj = NULL;
 266         const char *file, *ident;
 267         struct bpf_program *prog;
 268         int fd, len, err = -1;
 269         struct bpf_map *map;
 270         struct btf *btf;
 271         struct stat st;
 272
 273         if (!REQ_ARGS(1)) {
 274                 usage();
 275                 return -1;
 276         }
 277         file = GET_ARG();
 278
 279         if (argc) {
 280                 p_err("extra unknown arguments");
 281                 return -1;
 282         }
 283
 284         if (stat(file, &st)) {
 285                 p_err("failed to stat() %s: %s", file, strerror(errno));
 286                 return -1;
 287         }
 288         file_sz = st.st_size;
 289         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
 290         fd = open(file, O_RDONLY);
 291         if (fd < 0) {
 292                 p_err("failed to open() %s: %s", file, strerror(errno));
 293                 return -1;
 294         }
 295         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
 296         if (obj_data == MAP_FAILED) {
 297                 obj_data = NULL;
 298                 p_err("failed to mmap() %s: %s", file, strerror(errno));
 299                 goto out;
 300         }
 301         get_obj_name(obj_name, file);
 302         opts.object_name = obj_name;
 303         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 304         if (IS_ERR(obj)) {
 305                 char err_buf[256];
 306
 307                 libbpf_strerror(PTR_ERR(obj), err_buf, sizeof(err_buf));
 308                 p_err("failed to open BPF object file: %s", err_buf);
 309                 obj = NULL;
 310                 goto out;
 311         }
 312
 313         bpf_object__for_each_map(map, obj) {
 314                 ident = get_map_ident(map);
 315                 if (!ident) {
 316                         p_err("ignoring unrecognized internal map '%s'...",
 317                               bpf_map__name(map));
 318                         continue;
 319                 }
 320                 map_cnt++;
 321         }
 322         bpf_object__for_each_program(prog, obj) {
 323                 prog_cnt++;
 324         }
 325
 326         get_header_guard(header_guard, obj_name);
 327         codegen("\
 328                 \n\
 329                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
 330                                                                             \n\
 331                 /* THIS FILE IS AUTOGENERATED! */                           \n\
 332                 #ifndef %2$s                                                \n\
 333                 #define %2$s                                                \n\
 334                                                                             \n\
 335                 #include <stdlib.h>                                         \n\
 336                 #include <bpf/libbpf.h>                                     \n\
 337                                                                             \n\
 338                 struct %1$s {                                               \n\
 339                         struct bpf_object_skeleton *skeleton;               \n\
 340                         struct bpf_object *obj;                             \n\
 341                 ",
 342                 obj_name, header_guard
 343         );
 344
 345         if (map_cnt) {
 346                 printf("\tstruct {\n");
 347                 bpf_object__for_each_map(map, obj) {
 348                         ident = get_map_ident(map);
 349                         if (!ident)
 350                                 continue;
 351                         printf("\t\tstruct bpf_map *%s;\n", ident);
 352                 }
 353                 printf("\t} maps;\n");
 354         }
 355
 356         if (prog_cnt) {
 357                 printf("\tstruct {\n");
 358                 bpf_object__for_each_program(prog, obj) {
 359                         printf("\t\tstruct bpf_program *%s;\n",
 360                                bpf_program__name(prog));
 361                 }
 362                 printf("\t} progs;\n");
 363                 printf("\tstruct {\n");
 364                 bpf_object__for_each_program(prog, obj) {
 365                         printf("\t\tstruct bpf_link *%s;\n",
 366                                bpf_program__name(prog));
 367                 }
 368                 printf("\t} links;\n");
 369         }
 370
 371         btf = bpf_object__btf(obj);
 372         if (btf) {
 373                 err = codegen_datasecs(obj, obj_name);
 374                 if (err)
 375                         goto out;
 376         }
 377
 378         codegen("\
 379                 \n\
 380                 };                                                          \n\
 381                                                                             \n\
 382                 static void                                                 \n\
 383                 %1$s__destroy(struct %1$s *obj)                             \n\
 384                 {                                                           \n\
 385                         if (!obj)                                           \n\
 386                                 return;                                     \n\
 387                         if (obj->skeleton)                                  \n\
 388                                 bpf_object__destroy_skeleton(obj->skeleton);\n\
 389                         free(obj);                                          \n\
 390                 }                                                           \n\
 391                                                                             \n\
 392                 static inline int                                           \n\
 393                 %1$s__create_skeleton(struct %1$s *obj);                    \n\
 394                                                                             \n\
 395                 static inline struct %1$s *                                 \n\
 396                 %1$s__open_opts(const struct bpf_object_open_opts *opts)    \n\
 397                 {                                                           \n\
 398                         struct %1$s *obj;                                   \n\
 399                                                                             \n\
 400                         obj = (typeof(obj))calloc(1, sizeof(*obj));         \n\
 401                         if (!obj)                                           \n\
 402                                 return NULL;                                \n\
 403                         if (%1$s__create_skeleton(obj))                     \n\
 404                                 goto err;                                   \n\
 405                         if (bpf_object__open_skeleton(obj->skeleton, opts)) \n\
 406                                 goto err;                                   \n\
 407                                                                             \n\
 408                         return obj;                                         \n\
 409                 err:                                                        \n\
 410                         %1$s__destroy(obj);                                 \n\
 411                         return NULL;                                        \n\
 412                 }                                                           \n\
 413                                                                             \n\
 414                 static inline struct %1$s *                                 \n\
 415                 %1$s__open(void)                                            \n\
 416                 {                                                           \n\
 417                         return %1$s__open_opts(NULL);                       \n\
 418                 }                                                           \n\
 419                                                                             \n\
 420                 static inline int                                           \n\
 421                 %1$s__load(struct %1$s *obj)                                \n\
 422                 {                                                           \n\
 423                         return bpf_object__load_skeleton(obj->skeleton);    \n\
 424                 }                                                           \n\
 425                                                                             \n\
 426                 static inline struct %1$s *                                 \n\
 427                 %1$s__open_and_load(void)                                   \n\
 428                 {                                                           \n\
 429                         struct %1$s *obj;                                   \n\
 430                                                                             \n\
 431                         obj = %1$s__open();                                 \n\
 432                         if (!obj)                                           \n\
 433                                 return NULL;                                \n\
 434                         if (%1$s__load(obj)) {                              \n\
 435                                 %1$s__destroy(obj);                         \n\
 436                                 return NULL;                                \n\
 437                         }                                                   \n\
 438                         return obj;                                         \n\
 439                 }                                                           \n\
 440                                                                             \n\
 441                 static inline int                                           \n\
 442                 %1$s__attach(struct %1$s *obj)                              \n\
 443                 {                                                           \n\
 444                         return bpf_object__attach_skeleton(obj->skeleton);  \n\
 445                 }                                                           \n\
 446                                                                             \n\
 447                 static inline void                                          \n\
 448                 %1$s__detach(struct %1$s *obj)                              \n\
 449                 {                                                           \n\
 450                         return bpf_object__detach_skeleton(obj->skeleton);  \n\
 451                 }                                                           \n\
 452                 ",
 453                 obj_name
 454         );
 455
 456         codegen("\
 457                 \n\
 458                                                                             \n\
 459                 static inline int                                           \n\
 460                 %1$s__create_skeleton(struct %1$s *obj)                     \n\
 461                 {                                                           \n\
 462                         struct bpf_object_skeleton *s;                      \n\
 463                                                                             \n\
 464                         s = (typeof(s))calloc(1, sizeof(*s));               \n\
 465                         if (!s)                                             \n\
 466                                 return -1;                                  \n\
 467                         obj->skeleton = s;                                  \n\
 468                                                                             \n\
 469                         s->sz = sizeof(*s);                                 \n\
 470                         s->name = \"%1$s\";                                 \n\
 471                         s->obj = &obj->obj;                                 \n\
 472                 ",
 473                 obj_name
 474         );
 475         if (map_cnt) {
 476                 codegen("\
 477                         \n\
 478                                                                             \n\
 479                                 /* maps */                                  \n\
 480                                 s->map_cnt = %zu;                           \n\
 481                                 s->map_skel_sz = sizeof(*s->maps);          \n\
 482                                 s->maps = (typeof(s->maps))calloc(s->map_cnt, s->map_skel_sz);\n\
 483                                 if (!s->maps)                               \n\
 484                                         goto err;                           \n\
 485                         ",
 486                         map_cnt
 487                 );
 488                 i = 0;
 489                 bpf_object__for_each_map(map, obj) {
 490                         ident = get_map_ident(map);
 491
 492                         if (!ident)
 493                                 continue;
 494
 495                         codegen("\
 496                                 \n\
 497                                                                             \n\
 498                                         s->maps[%zu].name = \"%s\";         \n\
 499                                         s->maps[%zu].map = &obj->maps.%s;   \n\
 500                                 ",
 501                                 i, bpf_map__name(map), i, ident);
 502                         /* memory-mapped internal maps */
 503                         if (bpf_map__is_internal(map) &&
 504                             (bpf_map__def(map)->map_flags & BPF_F_MMAPABLE)) {
 505                                 printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
 506                                        i, ident);
 507                         }
 508                         i++;
 509                 }
 510         }
 511         if (prog_cnt) {
 512                 codegen("\
 513                         \n\
 514                                                                             \n\
 515                                 /* programs */                              \n\
 516                                 s->prog_cnt = %zu;                          \n\
 517                                 s->prog_skel_sz = sizeof(*s->progs);        \n\
 518                                 s->progs = (typeof(s->progs))calloc(s->prog_cnt, s->prog_skel_sz);\n\
 519                                 if (!s->progs)                              \n\
 520                                         goto err;                           \n\
 521                         ",
 522                         prog_cnt
 523                 );
 524                 i = 0;
 525                 bpf_object__for_each_program(prog, obj) {
 526                         codegen("\
 527                                 \n\
 528                                                                             \n\
 529                                         s->progs[%1$zu].name = \"%2$s\";    \n\
 530                                         s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
 531                                         s->progs[%1$zu].link = &obj->links.%2$s;\n\
 532                                 ",
 533                                 i, bpf_program__name(prog));
 534                         i++;
 535                 }
 536         }
 537         codegen("\
 538                 \n\
 539                                                                             \n\
 540                         s->data_sz = %d;                                    \n\
 541                         s->data = (void *)\"\\                              \n\
 542                 ",
 543                 file_sz);
 544
 545         /* embed contents of BPF object file */
 546         for (i = 0, len = 0; i < file_sz; i++) {
 547                 int w = obj_data[i] ? 4 : 2;
 548
 549                 len += w;
 550                 if (len > 78) {
 551                         printf("\\\n");
 552                         len = w;
 553                 }
 554                 if (!obj_data[i])
 555                         printf("\\0");
 556                 else
 557                         printf("\\x%02x", (unsigned char)obj_data[i]);
 558         }
 559
 560         codegen("\
 561                 \n\
 562                 \";                                                         \n\
 563                                                                             \n\
 564                         return 0;                                           \n\
 565                 err:                                                        \n\
 566                         bpf_object__destroy_skeleton(s);                    \n\
 567                         return -1;                                          \n\
 568                 }                                                           \n\
 569                                                                             \n\
 570                 #endif /* %s */                                             \n\
 571                 ",
 572                 header_guard);
 573         err = 0;
 574 out:
 575         bpf_object__close(obj);
 576         if (obj_data)
 577                 munmap(obj_data, mmap_sz);
 578         close(fd);
 579         return err;
 580 }
 581
 582 static int do_help(int argc, char **argv)
 583 {
 584         if (json_output) {
 585                 jsonw_null(json_wtr);
 586                 return 0;
 587         }
 588
 589         fprintf(stderr,
 590                 "Usage: %1$s %2$s skeleton FILE\n"
 591                 "       %1$s %2$s help\n"
 592                 "\n"
 593                 "       " HELP_SPEC_OPTIONS "\n"
 594                 "",
 595                 bin_name, "gen");
 596
 597         return 0;
 598 }
 599
 600 static const struct cmd cmds[] = {
 601         { "skeleton",   do_skeleton },
 602         { "help",       do_help },
 603         { 0 }
 604 };
 605
 606 int do_gen(int argc, char **argv)
 607 {
 608         return cmd_select(cmds, argc, argv, do_help);
 609 }