scripts/kallsyms.c

   1 /* Generate assembler source containing symbol information
   2  *
   3  * Copyright 2002       by Kai Germaschewski
   4  *
   5  * This software may be used and distributed according to the terms
   6  * of the GNU General Public License, incorporated herein by reference.
   7  *
   8  * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S
   9  *
  10  *      Table compression uses all the unused char codes on the symbols and
  11  *  maps these to the most used substrings (tokens). For instance, it might
  12  *  map char code 0xF7 to represent "write_" and then in every symbol where
  13  *  "write_" appears it can be replaced by 0xF7, saving 5 bytes.
  14  *      The used codes themselves are also placed in the table so that the
  15  *  decompresion can work without "special cases".
  16  *      Applied to kernel symbols, this usually produces a compression ratio
  17  *  of about 50%.
  18  *
  19  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <ctype.h>
  25 #include <limits.h>
  26
  27 #ifndef ARRAY_SIZE
  28 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
  29 #endif
  30
  31 #define KSYM_NAME_LEN           128
  32
  33 struct sym_entry {
  34         unsigned long long addr;
  35         unsigned int len;
  36         unsigned int start_pos;
  37         unsigned char *sym;
  38         unsigned int percpu_absolute;
  39 };
  40
  41 struct addr_range {
  42         const char *start_sym, *end_sym;
  43         unsigned long long start, end;
  44 };
  45
  46 static unsigned long long _text;
  47 static unsigned long long relative_base;
  48 static struct addr_range text_ranges[] = {
  49         { "_stext",     "_etext"     },
  50         { "_sinittext", "_einittext" },
  51         { "_stext_l1",  "_etext_l1"  }, /* Blackfin on-chip L1 inst SRAM */
  52         { "_stext_l2",  "_etext_l2"  }, /* Blackfin on-chip L2 SRAM */
  53 };
  54 #define text_range_text     (&text_ranges[0])
  55 #define text_range_inittext (&text_ranges[1])
  56
  57 static struct addr_range percpu_range = {
  58         "__per_cpu_start", "__per_cpu_end", -1ULL, 0
  59 };
  60
  61 static struct sym_entry *table;
  62 static unsigned int table_size, table_cnt;
  63 static int all_symbols = 0;
  64 static int absolute_percpu = 0;
  65 static char symbol_prefix_char = '\0';
  66 static int base_relative = 0;
  67
  68 int token_profit[0x10000];
  69
  70 /* the table that holds the result of the compression */
  71 unsigned char best_table[256][2];
  72 unsigned char best_table_len[256];
  73
  74
  75 static void usage(void)
  76 {
  77         fprintf(stderr, "Usage: kallsyms [--all-symbols] "
  78                         "[--symbol-prefix=<prefix char>] "
  79                         "[--base-relative] < in.map > out.S\n");
  80         exit(1);
  81 }
  82
  83 /*
  84  * This ignores the intensely annoying "mapping symbols" found
  85  * in ARM ELF files: $a, $t and $d.
  86  */
  87 static inline int is_arm_mapping_symbol(const char *str)
  88 {
  89         return str[0] == '$' && strchr("axtd", str[1])
  90                && (str[2] == '\0' || str[2] == '.');
  91 }
  92
  93 static int check_symbol_range(const char *sym, unsigned long long addr,
  94                               struct addr_range *ranges, int entries)
  95 {
  96         size_t i;
  97         struct addr_range *ar;
  98
  99         for (i = 0; i < entries; ++i) {
 100                 ar = &ranges[i];
 101
 102                 if (strcmp(sym, ar->start_sym) == 0) {
 103                         ar->start = addr;
 104                         return 0;
 105                 } else if (strcmp(sym, ar->end_sym) == 0) {
 106                         ar->end = addr;
 107                         return 0;
 108                 }
 109         }
 110
 111         return 1;
 112 }
 113
 114 static int read_symbol(FILE *in, struct sym_entry *s)
 115 {
 116         char str[500];
 117         char *sym, stype;
 118         int rc;
 119
 120         rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
 121         if (rc != 3) {
 122                 if (rc != EOF && fgets(str, 500, in) == NULL)
 123                         fprintf(stderr, "Read error or end of file.\n");
 124                 return -1;
 125         }
 126         if (strlen(str) > KSYM_NAME_LEN) {
 127                 fprintf(stderr, "Symbol %s too long for kallsyms (%zu vs %d).\n"
 128                                 "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
 129                         str, strlen(str), KSYM_NAME_LEN);
 130                 return -1;
 131         }
 132
 133         sym = str;
 134         /* skip prefix char */
 135         if (symbol_prefix_char && str[0] == symbol_prefix_char)
 136                 sym++;
 137
 138         /* Ignore most absolute/undefined (?) symbols. */
 139         if (strcmp(sym, "_text") == 0)
 140                 _text = s->addr;
 141         else if (check_symbol_range(sym, s->addr, text_ranges,
 142                                     ARRAY_SIZE(text_ranges)) == 0)
 143                 /* nothing to do */;
 144         else if (toupper(stype) == 'A')
 145         {
 146                 /* Keep these useful absolute symbols */
 147                 if (strcmp(sym, "__kernel_syscall_via_break") &&
 148                     strcmp(sym, "__kernel_syscall_via_epc") &&
 149                     strcmp(sym, "__kernel_sigtramp") &&
 150                     strcmp(sym, "__gp"))
 151                         return -1;
 152
 153         }
 154         else if (toupper(stype) == 'U' ||
 155                  is_arm_mapping_symbol(sym))
 156                 return -1;
 157         /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
 158         else if (str[0] == '$')
 159                 return -1;
 160         /* exclude debugging symbols */
 161         else if (stype == 'N' || stype == 'n')
 162                 return -1;
 163
 164         /* include the type field in the symbol name, so that it gets
 165          * compressed together */
 166         s->len = strlen(str) + 1;
 167         s->sym = malloc(s->len + 1);
 168         if (!s->sym) {
 169                 fprintf(stderr, "kallsyms failure: "
 170                         "unable to allocate required amount of memory\n");
 171                 exit(EXIT_FAILURE);
 172         }
 173         strcpy((char *)s->sym + 1, str);
 174         s->sym[0] = stype;
 175
 176         s->percpu_absolute = 0;
 177
 178         /* Record if we've found __per_cpu_start/end. */
 179         check_symbol_range(sym, s->addr, &percpu_range, 1);
 180
 181         return 0;
 182 }
 183
 184 static int symbol_in_range(struct sym_entry *s, struct addr_range *ranges,
 185                            int entries)
 186 {
 187         size_t i;
 188         struct addr_range *ar;
 189
 190         for (i = 0; i < entries; ++i) {
 191                 ar = &ranges[i];
 192
 193                 if (s->addr >= ar->start && s->addr <= ar->end)
 194                         return 1;
 195         }
 196
 197         return 0;
 198 }
 199
 200 static int symbol_valid(struct sym_entry *s)
 201 {
 202         /* Symbols which vary between passes.  Passes 1 and 2 must have
 203          * identical symbol lists.  The kallsyms_* symbols below are only added
 204          * after pass 1, they would be included in pass 2 when --all-symbols is
 205          * specified so exclude them to get a stable symbol list.
 206          */
 207         static char *special_symbols[] = {
 208                 "kallsyms_addresses",
 209                 "kallsyms_offsets",
 210                 "kallsyms_relative_base",
 211                 "kallsyms_num_syms",
 212                 "kallsyms_names",
 213                 "kallsyms_markers",
 214                 "kallsyms_token_table",
 215                 "kallsyms_token_index",
 216
 217         /* Exclude linker generated symbols which vary between passes */
 218                 "_SDA_BASE_",           /* ppc */
 219                 "_SDA2_BASE_",          /* ppc */
 220                 NULL };
 221
 222         static char *special_prefixes[] = {
 223                 "__crc_",               /* modversions */
 224                 "__efistub_",           /* arm64 EFI stub namespace */
 225                 NULL };
 226
 227         static char *special_suffixes[] = {
 228                 "_veneer",              /* arm */
 229                 "_from_arm",            /* arm */
 230                 "_from_thumb",          /* arm */
 231                 NULL };
 232
 233         int i;
 234         char *sym_name = (char *)s->sym + 1;
 235
 236         /* skip prefix char */
 237         if (symbol_prefix_char && *sym_name == symbol_prefix_char)
 238                 sym_name++;
 239
 240
 241         /* if --all-symbols is not specified, then symbols outside the text
 242          * and inittext sections are discarded */
 243         if (!all_symbols) {
 244                 if (symbol_in_range(s, text_ranges,
 245                                     ARRAY_SIZE(text_ranges)) == 0)
 246                         return 0;
 247                 /* Corner case.  Discard any symbols with the same value as
 248                  * _etext _einittext; they can move between pass 1 and 2 when
 249                  * the kallsyms data are added.  If these symbols move then
 250                  * they may get dropped in pass 2, which breaks the kallsyms
 251                  * rules.
 252                  */
 253                 if ((s->addr == text_range_text->end &&
 254                                 strcmp(sym_name,
 255                                        text_range_text->end_sym)) ||
 256                     (s->addr == text_range_inittext->end &&
 257                                 strcmp(sym_name,
 258                                        text_range_inittext->end_sym)))
 259                         return 0;
 260         }
 261
 262         /* Exclude symbols which vary between passes. */
 263         for (i = 0; special_symbols[i]; i++)
 264                 if (strcmp(sym_name, special_symbols[i]) == 0)
 265                         return 0;
 266
 267         for (i = 0; special_prefixes[i]; i++) {
 268                 int l = strlen(special_prefixes[i]);
 269
 270                 if (l <= strlen(sym_name) &&
 271                     strncmp(sym_name, special_prefixes[i], l) == 0)
 272                         return 0;
 273         }
 274
 275         for (i = 0; special_suffixes[i]; i++) {
 276                 int l = strlen(sym_name) - strlen(special_suffixes[i]);
 277
 278                 if (l >= 0 && strcmp(sym_name + l, special_suffixes[i]) == 0)
 279                         return 0;
 280         }
 281
 282         return 1;
 283 }
 284
 285 static void read_map(FILE *in)
 286 {
 287         while (!feof(in)) {
 288                 if (table_cnt >= table_size) {
 289                         table_size += 10000;
 290                         table = realloc(table, sizeof(*table) * table_size);
 291                         if (!table) {
 292                                 fprintf(stderr, "out of memory\n");
 293                                 exit (1);
 294                         }
 295                 }
 296                 if (read_symbol(in, &table[table_cnt]) == 0) {
 297                         table[table_cnt].start_pos = table_cnt;
 298                         table_cnt++;
 299                 }
 300         }
 301 }
 302
 303 static void output_label(char *label)
 304 {
 305         if (symbol_prefix_char)
 306                 printf(".globl %c%s\n", symbol_prefix_char, label);
 307         else
 308                 printf(".globl %s\n", label);
 309         printf("\tALGN\n");
 310         if (symbol_prefix_char)
 311                 printf("%c%s:\n", symbol_prefix_char, label);
 312         else
 313                 printf("%s:\n", label);
 314 }
 315
 316 /* uncompress a compressed symbol. When this function is called, the best table
 317  * might still be compressed itself, so the function needs to be recursive */
 318 static int expand_symbol(unsigned char *data, int len, char *result)
 319 {
 320         int c, rlen, total=0;
 321
 322         while (len) {
 323                 c = *data;
 324                 /* if the table holds a single char that is the same as the one
 325                  * we are looking for, then end the search */
 326                 if (best_table[c][0]==c && best_table_len[c]==1) {
 327                         *result++ = c;
 328                         total++;
 329                 } else {
 330                         /* if not, recurse and expand */
 331                         rlen = expand_symbol(best_table[c], best_table_len[c], result);
 332                         total += rlen;
 333                         result += rlen;
 334                 }
 335                 data++;
 336                 len--;
 337         }
 338         *result=0;
 339
 340         return total;
 341 }
 342
 343 static int symbol_absolute(struct sym_entry *s)
 344 {
 345         return s->percpu_absolute;
 346 }
 347
 348 static void write_src(void)
 349 {
 350         unsigned int i, k, off;
 351         unsigned int best_idx[256];
 352         unsigned int *markers;
 353         char buf[KSYM_NAME_LEN];
 354
 355         printf("#include <asm/types.h>\n");
 356         printf("#if BITS_PER_LONG == 64\n");
 357         printf("#define PTR .quad\n");
 358         printf("#define ALGN .align 8\n");
 359         printf("#else\n");
 360         printf("#define PTR .long\n");
 361         printf("#define ALGN .align 4\n");
 362         printf("#endif\n");
 363
 364         printf("\t.section .rodata, \"a\"\n");
 365
 366         /* Provide proper symbols relocatability by their relativeness
 367          * to a fixed anchor point in the runtime image, either '_text'
 368          * for absolute address tables, in which case the linker will
 369          * emit the final addresses at build time. Otherwise, use the
 370          * offset relative to the lowest value encountered of all relative
 371          * symbols, and emit non-relocatable fixed offsets that will be fixed
 372          * up at runtime.
 373          *
 374          * The symbol names cannot be used to construct normal symbol
 375          * references as the list of symbols contains symbols that are
 376          * declared static and are private to their .o files.  This prevents
 377          * .tmp_kallsyms.o or any other object from referencing them.
 378          */
 379         if (!base_relative)
 380                 output_label("kallsyms_addresses");
 381         else
 382                 output_label("kallsyms_offsets");
 383
 384         for (i = 0; i < table_cnt; i++) {
 385                 if (base_relative) {
 386                         long long offset;
 387                         int overflow;
 388
 389                         if (!absolute_percpu) {
 390                                 offset = table[i].addr - relative_base;
 391                                 overflow = (offset < 0 || offset > UINT_MAX);
 392                         } else if (symbol_absolute(&table[i])) {
 393                                 offset = table[i].addr;
 394                                 overflow = (offset < 0 || offset > INT_MAX);
 395                         } else {
 396                                 offset = relative_base - table[i].addr - 1;
 397                                 overflow = (offset < INT_MIN || offset >= 0);
 398                         }
 399                         if (overflow) {
 400                                 fprintf(stderr, "kallsyms failure: "
 401                                         "%s symbol value %#llx out of range in relative mode\n",
 402                                         symbol_absolute(&table[i]) ? "absolute" : "relative",
 403                                         table[i].addr);
 404                                 exit(EXIT_FAILURE);
 405                         }
 406                         printf("\t.long\t%#x\n", (int)offset);
 407                 } else if (!symbol_absolute(&table[i])) {
 408                         if (_text <= table[i].addr)
 409                                 printf("\tPTR\t_text + %#llx\n",
 410                                         table[i].addr - _text);
 411                         else
 412                                 printf("\tPTR\t_text - %#llx\n",
 413                                         _text - table[i].addr);
 414                 } else {
 415                         printf("\tPTR\t%#llx\n", table[i].addr);
 416                 }
 417         }
 418         printf("\n");
 419
 420         if (base_relative) {
 421                 output_label("kallsyms_relative_base");
 422                 printf("\tPTR\t_text - %#llx\n", _text - relative_base);
 423                 printf("\n");
 424         }
 425
 426         output_label("kallsyms_num_syms");
 427         printf("\tPTR\t%d\n", table_cnt);
 428         printf("\n");
 429
 430         /* table of offset markers, that give the offset in the compressed stream
 431          * every 256 symbols */
 432         markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
 433         if (!markers) {
 434                 fprintf(stderr, "kallsyms failure: "
 435                         "unable to allocate required memory\n");
 436                 exit(EXIT_FAILURE);
 437         }
 438
 439         output_label("kallsyms_names");
 440         off = 0;
 441         for (i = 0; i < table_cnt; i++) {
 442                 if ((i & 0xFF) == 0)
 443                         markers[i >> 8] = off;
 444
 445                 printf("\t.byte 0x%02x", table[i].len);
 446                 for (k = 0; k < table[i].len; k++)
 447                         printf(", 0x%02x", table[i].sym[k]);
 448                 printf("\n");
 449
 450                 off += table[i].len + 1;
 451         }
 452         printf("\n");
 453
 454         output_label("kallsyms_markers");
 455         for (i = 0; i < ((table_cnt + 255) >> 8); i++)
 456                 printf("\tPTR\t%d\n", markers[i]);
 457         printf("\n");
 458
 459         free(markers);
 460
 461         output_label("kallsyms_token_table");
 462         off = 0;
 463         for (i = 0; i < 256; i++) {
 464                 best_idx[i] = off;
 465                 expand_symbol(best_table[i], best_table_len[i], buf);
 466                 printf("\t.asciz\t\"%s\"\n", buf);
 467                 off += strlen(buf) + 1;
 468         }
 469         printf("\n");
 470
 471         output_label("kallsyms_token_index");
 472         for (i = 0; i < 256; i++)
 473                 printf("\t.short\t%d\n", best_idx[i]);
 474         printf("\n");
 475 }
 476
 477
 478 /* table lookup compression functions */
 479
 480 /* count all the possible tokens in a symbol */
 481 static void learn_symbol(unsigned char *symbol, int len)
 482 {
 483         int i;
 484
 485         for (i = 0; i < len - 1; i++)
 486                 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
 487 }
 488
 489 /* decrease the count for all the possible tokens in a symbol */
 490 static void forget_symbol(unsigned char *symbol, int len)
 491 {
 492         int i;
 493
 494         for (i = 0; i < len - 1; i++)
 495                 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
 496 }
 497
 498 /* remove all the invalid symbols from the table and do the initial token count */
 499 static void build_initial_tok_table(void)
 500 {
 501         unsigned int i, pos;
 502
 503         pos = 0;
 504         for (i = 0; i < table_cnt; i++) {
 505                 if ( symbol_valid(&table[i]) ) {
 506                         if (pos != i)
 507                                 table[pos] = table[i];
 508                         learn_symbol(table[pos].sym, table[pos].len);
 509                         pos++;
 510                 }
 511         }
 512         table_cnt = pos;
 513 }
 514
 515 static void *find_token(unsigned char *str, int len, unsigned char *token)
 516 {
 517         int i;
 518
 519         for (i = 0; i < len - 1; i++) {
 520                 if (str[i] == token[0] && str[i+1] == token[1])
 521                         return &str[i];
 522         }
 523         return NULL;
 524 }
 525
 526 /* replace a given token in all the valid symbols. Use the sampled symbols
 527  * to update the counts */
 528 static void compress_symbols(unsigned char *str, int idx)
 529 {
 530         unsigned int i, len, size;
 531         unsigned char *p1, *p2;
 532
 533         for (i = 0; i < table_cnt; i++) {
 534
 535                 len = table[i].len;
 536                 p1 = table[i].sym;
 537
 538                 /* find the token on the symbol */
 539                 p2 = find_token(p1, len, str);
 540                 if (!p2) continue;
 541
 542                 /* decrease the counts for this symbol's tokens */
 543                 forget_symbol(table[i].sym, len);
 544
 545                 size = len;
 546
 547                 do {
 548                         *p2 = idx;
 549                         p2++;
 550                         size -= (p2 - p1);
 551                         memmove(p2, p2 + 1, size);
 552                         p1 = p2;
 553                         len--;
 554
 555                         if (size < 2) break;
 556
 557                         /* find the token on the symbol */
 558                         p2 = find_token(p1, size, str);
 559
 560                 } while (p2);
 561
 562                 table[i].len = len;
 563
 564                 /* increase the counts for this symbol's new tokens */
 565                 learn_symbol(table[i].sym, len);
 566         }
 567 }
 568
 569 /* search the token with the maximum profit */
 570 static int find_best_token(void)
 571 {
 572         int i, best, bestprofit;
 573
 574         bestprofit=-10000;
 575         best = 0;
 576
 577         for (i = 0; i < 0x10000; i++) {
 578                 if (token_profit[i] > bestprofit) {
 579                         best = i;
 580                         bestprofit = token_profit[i];
 581                 }
 582         }
 583         return best;
 584 }
 585
 586 /* this is the core of the algorithm: calculate the "best" table */
 587 static void optimize_result(void)
 588 {
 589         int i, best;
 590
 591         /* using the '\0' symbol last allows compress_symbols to use standard
 592          * fast string functions */
 593         for (i = 255; i >= 0; i--) {
 594
 595                 /* if this table slot is empty (it is not used by an actual
 596                  * original char code */
 597                 if (!best_table_len[i]) {
 598
 599                         /* find the token with the breates profit value */
 600                         best = find_best_token();
 601                         if (token_profit[best] == 0)
 602                                 break;
 603
 604                         /* place it in the "best" table */
 605                         best_table_len[i] = 2;
 606                         best_table[i][0] = best & 0xFF;
 607                         best_table[i][1] = (best >> 8) & 0xFF;
 608
 609                         /* replace this token in all the valid symbols */
 610                         compress_symbols(best_table[i], i);
 611                 }
 612         }
 613 }
 614
 615 /* start by placing the symbols that are actually used on the table */
 616 static void insert_real_symbols_in_table(void)
 617 {
 618         unsigned int i, j, c;
 619
 620         memset(best_table, 0, sizeof(best_table));
 621         memset(best_table_len, 0, sizeof(best_table_len));
 622
 623         for (i = 0; i < table_cnt; i++) {
 624                 for (j = 0; j < table[i].len; j++) {
 625                         c = table[i].sym[j];
 626                         best_table[c][0]=c;
 627                         best_table_len[c]=1;
 628                 }
 629         }
 630 }
 631
 632 static void optimize_token_table(void)
 633 {
 634         build_initial_tok_table();
 635
 636         insert_real_symbols_in_table();
 637
 638         /* When valid symbol is not registered, exit to error */
 639         if (!table_cnt) {
 640                 fprintf(stderr, "No valid symbol.\n");
 641                 exit(1);
 642         }
 643
 644         optimize_result();
 645 }
 646
 647 /* guess for "linker script provide" symbol */
 648 static int may_be_linker_script_provide_symbol(const struct sym_entry *se)
 649 {
 650         const char *symbol = (char *)se->sym + 1;
 651         int len = se->len - 1;
 652
 653         if (len < 8)
 654                 return 0;
 655
 656         if (symbol[0] != '_' || symbol[1] != '_')
 657                 return 0;
 658
 659         /* __start_XXXXX */
 660         if (!memcmp(symbol + 2, "start_", 6))
 661                 return 1;
 662
 663         /* __stop_XXXXX */
 664         if (!memcmp(symbol + 2, "stop_", 5))
 665                 return 1;
 666
 667         /* __end_XXXXX */
 668         if (!memcmp(symbol + 2, "end_", 4))
 669                 return 1;
 670
 671         /* __XXXXX_start */
 672         if (!memcmp(symbol + len - 6, "_start", 6))
 673                 return 1;
 674
 675         /* __XXXXX_end */
 676         if (!memcmp(symbol + len - 4, "_end", 4))
 677                 return 1;
 678
 679         return 0;
 680 }
 681
 682 static int prefix_underscores_count(const char *str)
 683 {
 684         const char *tail = str;
 685
 686         while (*tail == '_')
 687                 tail++;
 688
 689         return tail - str;
 690 }
 691
 692 static int compare_symbols(const void *a, const void *b)
 693 {
 694         const struct sym_entry *sa;
 695         const struct sym_entry *sb;
 696         int wa, wb;
 697
 698         sa = a;
 699         sb = b;
 700
 701         /* sort by address first */
 702         if (sa->addr > sb->addr)
 703                 return 1;
 704         if (sa->addr < sb->addr)
 705                 return -1;
 706
 707         /* sort by "weakness" type */
 708         wa = (sa->sym[0] == 'w') || (sa->sym[0] == 'W');
 709         wb = (sb->sym[0] == 'w') || (sb->sym[0] == 'W');
 710         if (wa != wb)
 711                 return wa - wb;
 712
 713         /* sort by "linker script provide" type */
 714         wa = may_be_linker_script_provide_symbol(sa);
 715         wb = may_be_linker_script_provide_symbol(sb);
 716         if (wa != wb)
 717                 return wa - wb;
 718
 719         /* sort by the number of prefix underscores */
 720         wa = prefix_underscores_count((const char *)sa->sym + 1);
 721         wb = prefix_underscores_count((const char *)sb->sym + 1);
 722         if (wa != wb)
 723                 return wa - wb;
 724
 725         /* sort by initial order, so that other symbols are left undisturbed */
 726         return sa->start_pos - sb->start_pos;
 727 }
 728
 729 static void sort_symbols(void)
 730 {
 731         qsort(table, table_cnt, sizeof(struct sym_entry), compare_symbols);
 732 }
 733
 734 static void make_percpus_absolute(void)
 735 {
 736         unsigned int i;
 737
 738         for (i = 0; i < table_cnt; i++)
 739                 if (symbol_in_range(&table[i], &percpu_range, 1)) {
 740                         /*
 741                          * Keep the 'A' override for percpu symbols to
 742                          * ensure consistent behavior compared to older
 743                          * versions of this tool.
 744                          */
 745                         table[i].sym[0] = 'A';
 746                         table[i].percpu_absolute = 1;
 747                 }
 748 }
 749
 750 /* find the minimum non-absolute symbol address */
 751 static void record_relative_base(void)
 752 {
 753         unsigned int i;
 754
 755         relative_base = -1ULL;
 756         for (i = 0; i < table_cnt; i++)
 757                 if (!symbol_absolute(&table[i]) &&
 758                     table[i].addr < relative_base)
 759                         relative_base = table[i].addr;
 760 }
 761
 762 int main(int argc, char **argv)
 763 {
 764         if (argc >= 2) {
 765                 int i;
 766                 for (i = 1; i < argc; i++) {
 767                         if(strcmp(argv[i], "--all-symbols") == 0)
 768                                 all_symbols = 1;
 769                         else if (strcmp(argv[i], "--absolute-percpu") == 0)
 770                                 absolute_percpu = 1;
 771                         else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
 772                                 char *p = &argv[i][16];
 773                                 /* skip quote */
 774                                 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
 775                                         p++;
 776                                 symbol_prefix_char = *p;
 777                         } else if (strcmp(argv[i], "--base-relative") == 0)
 778                                 base_relative = 1;
 779                         else
 780                                 usage();
 781                 }
 782         } else if (argc != 1)
 783                 usage();
 784
 785         read_map(stdin);
 786         if (absolute_percpu)
 787                 make_percpus_absolute();
 788         if (base_relative)
 789                 record_relative_base();
 790         sort_symbols();
 791         optimize_token_table();
 792         write_src();
 793
 794         return 0;
 795 }