| 1 | /* ldctor.c -- constructor support routines |
| 2 | Copyright (C) 1991-2019 Free Software Foundation, Inc. |
| 3 | By Steve Chamberlain <sac@cygnus.com> |
| 4 | |
| 5 | This file is part of the GNU Binutils. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 20 | MA 02110-1301, USA. */ |
| 21 | |
| 22 | #include "sysdep.h" |
| 23 | #include "bfd.h" |
| 24 | #include "bfdlink.h" |
| 25 | #include "safe-ctype.h" |
| 26 | #include "ctf-api.h" |
| 27 | |
| 28 | #include "ld.h" |
| 29 | #include "ldexp.h" |
| 30 | #include "ldlang.h" |
| 31 | #include "ldmisc.h" |
| 32 | #include <ldgram.h> |
| 33 | #include "ldmain.h" |
| 34 | #include "ldctor.h" |
| 35 | |
| 36 | /* The list of statements needed to handle constructors. These are |
| 37 | invoked by the command CONSTRUCTORS in the linker script. */ |
| 38 | lang_statement_list_type constructor_list; |
| 39 | |
| 40 | /* Whether the constructors should be sorted. Note that this is |
| 41 | global for the entire link; we assume that there is only a single |
| 42 | CONSTRUCTORS command in the linker script. */ |
| 43 | bfd_boolean constructors_sorted; |
| 44 | |
| 45 | /* The sets we have seen. */ |
| 46 | struct set_info *sets; |
| 47 | |
| 48 | /* Add an entry to a set. H is the entry in the linker hash table. |
| 49 | RELOC is the relocation to use for an entry in the set. SECTION |
| 50 | and VALUE are the value to add. This is called during the first |
| 51 | phase of the link, when we are still gathering symbols together. |
| 52 | We just record the information now. The ldctor_build_sets |
| 53 | function will construct the sets. */ |
| 54 | |
| 55 | void |
| 56 | ldctor_add_set_entry (struct bfd_link_hash_entry *h, |
| 57 | bfd_reloc_code_real_type reloc, |
| 58 | const char *name, |
| 59 | asection *section, |
| 60 | bfd_vma value) |
| 61 | { |
| 62 | struct set_info *p; |
| 63 | struct set_element *e; |
| 64 | struct set_element **epp; |
| 65 | |
| 66 | for (p = sets; p != NULL; p = p->next) |
| 67 | if (p->h == h) |
| 68 | break; |
| 69 | |
| 70 | if (p == NULL) |
| 71 | { |
| 72 | p = (struct set_info *) xmalloc (sizeof (struct set_info)); |
| 73 | p->next = sets; |
| 74 | sets = p; |
| 75 | p->h = h; |
| 76 | p->reloc = reloc; |
| 77 | p->count = 0; |
| 78 | p->elements = NULL; |
| 79 | } |
| 80 | else |
| 81 | { |
| 82 | if (p->reloc != reloc) |
| 83 | { |
| 84 | einfo (_("%X%P: different relocs used in set %s\n"), |
| 85 | h->root.string); |
| 86 | return; |
| 87 | } |
| 88 | |
| 89 | /* Don't permit a set to be constructed from different object |
| 90 | file formats. The same reloc may have different results. We |
| 91 | actually could sometimes handle this, but the case is |
| 92 | unlikely to ever arise. Sometimes constructor symbols are in |
| 93 | unusual sections, such as the absolute section--this appears |
| 94 | to be the case in Linux a.out--and in such cases we just |
| 95 | assume everything is OK. */ |
| 96 | if (p->elements != NULL |
| 97 | && section->owner != NULL |
| 98 | && p->elements->section->owner != NULL |
| 99 | && strcmp (bfd_get_target (section->owner), |
| 100 | bfd_get_target (p->elements->section->owner)) != 0) |
| 101 | { |
| 102 | einfo (_("%X%P: different object file formats composing set %s\n"), |
| 103 | h->root.string); |
| 104 | return; |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | e = (struct set_element *) xmalloc (sizeof (struct set_element)); |
| 109 | e->u.next = NULL; |
| 110 | e->name = name; |
| 111 | e->section = section; |
| 112 | e->value = value; |
| 113 | |
| 114 | for (epp = &p->elements; *epp != NULL; epp = &(*epp)->u.next) |
| 115 | ; |
| 116 | *epp = e; |
| 117 | |
| 118 | ++p->count; |
| 119 | } |
| 120 | |
| 121 | /* Get the priority of a g++ global constructor or destructor from the |
| 122 | symbol name. */ |
| 123 | |
| 124 | static int |
| 125 | ctor_prio (const char *name) |
| 126 | { |
| 127 | /* The name will look something like _GLOBAL_$I$65535$test02__Fv. |
| 128 | There might be extra leading underscores, and the $ characters |
| 129 | might be something else. The I might be a D. */ |
| 130 | |
| 131 | while (*name == '_') |
| 132 | ++name; |
| 133 | |
| 134 | if (!CONST_STRNEQ (name, "GLOBAL_")) |
| 135 | return -1; |
| 136 | |
| 137 | name += sizeof "GLOBAL_" - 1; |
| 138 | |
| 139 | if (name[0] != name[2]) |
| 140 | return -1; |
| 141 | if (name[1] != 'I' && name[1] != 'D') |
| 142 | return -1; |
| 143 | if (!ISDIGIT (name[3])) |
| 144 | return -1; |
| 145 | |
| 146 | return atoi (name + 3); |
| 147 | } |
| 148 | |
| 149 | /* This function is used to sort constructor elements by priority. It |
| 150 | is called via qsort. */ |
| 151 | |
| 152 | static int |
| 153 | ctor_cmp (const void *p1, const void *p2) |
| 154 | { |
| 155 | const struct set_element *pe1 = *(const struct set_element **) p1; |
| 156 | const struct set_element *pe2 = *(const struct set_element **) p2; |
| 157 | const char *n1; |
| 158 | const char *n2; |
| 159 | int prio1; |
| 160 | int prio2; |
| 161 | |
| 162 | n1 = pe1->name; |
| 163 | if (n1 == NULL) |
| 164 | n1 = ""; |
| 165 | n2 = pe2->name; |
| 166 | if (n2 == NULL) |
| 167 | n2 = ""; |
| 168 | |
| 169 | /* We need to sort in reverse order by priority. When two |
| 170 | constructors have the same priority, we should maintain their |
| 171 | current relative position. */ |
| 172 | |
| 173 | prio1 = ctor_prio (n1); |
| 174 | prio2 = ctor_prio (n2); |
| 175 | |
| 176 | /* We sort in reverse order because that is what g++ expects. */ |
| 177 | if (prio1 < prio2) |
| 178 | return 1; |
| 179 | if (prio1 > prio2) |
| 180 | return -1; |
| 181 | |
| 182 | /* Force a stable sort. */ |
| 183 | if (pe1->u.idx < pe2->u.idx) |
| 184 | return -1; |
| 185 | if (pe1->u.idx > pe2->u.idx) |
| 186 | return 1; |
| 187 | return 0; |
| 188 | } |
| 189 | |
| 190 | /* This function is called after the first phase of the link and |
| 191 | before the second phase. At this point all set information has |
| 192 | been gathered. We now put the statements to build the sets |
| 193 | themselves into constructor_list. */ |
| 194 | |
| 195 | void |
| 196 | ldctor_build_sets (void) |
| 197 | { |
| 198 | static bfd_boolean called; |
| 199 | bfd_boolean header_printed; |
| 200 | struct set_info *p; |
| 201 | |
| 202 | /* The emulation code may call us directly, but we only want to do |
| 203 | this once. */ |
| 204 | if (called) |
| 205 | return; |
| 206 | called = TRUE; |
| 207 | |
| 208 | if (constructors_sorted) |
| 209 | { |
| 210 | for (p = sets; p != NULL; p = p->next) |
| 211 | { |
| 212 | int c, i; |
| 213 | struct set_element *e, *enext; |
| 214 | struct set_element **array; |
| 215 | |
| 216 | if (p->elements == NULL) |
| 217 | continue; |
| 218 | |
| 219 | c = 0; |
| 220 | for (e = p->elements; e != NULL; e = e->u.next) |
| 221 | ++c; |
| 222 | |
| 223 | array = (struct set_element **) xmalloc (c * sizeof *array); |
| 224 | |
| 225 | i = 0; |
| 226 | for (e = p->elements; e != NULL; e = enext) |
| 227 | { |
| 228 | array[i] = e; |
| 229 | enext = e->u.next; |
| 230 | e->u.idx = i; |
| 231 | ++i; |
| 232 | } |
| 233 | |
| 234 | qsort (array, c, sizeof *array, ctor_cmp); |
| 235 | |
| 236 | e = array[0]; |
| 237 | p->elements = e; |
| 238 | for (i = 0; i < c - 1; i++) |
| 239 | array[i]->u.next = array[i + 1]; |
| 240 | array[i]->u.next = NULL; |
| 241 | |
| 242 | free (array); |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | lang_list_init (&constructor_list); |
| 247 | push_stat_ptr (&constructor_list); |
| 248 | |
| 249 | header_printed = FALSE; |
| 250 | for (p = sets; p != NULL; p = p->next) |
| 251 | { |
| 252 | struct set_element *e; |
| 253 | reloc_howto_type *howto; |
| 254 | int reloc_size, size; |
| 255 | |
| 256 | /* If the symbol is defined, we may have been invoked from |
| 257 | collect, and the sets may already have been built, so we do |
| 258 | not do anything. */ |
| 259 | if (p->h->type == bfd_link_hash_defined |
| 260 | || p->h->type == bfd_link_hash_defweak) |
| 261 | continue; |
| 262 | |
| 263 | /* For each set we build: |
| 264 | set: |
| 265 | .long number_of_elements |
| 266 | .long element0 |
| 267 | ... |
| 268 | .long elementN |
| 269 | .long 0 |
| 270 | except that we use the right size instead of .long. When |
| 271 | generating relocatable output, we generate relocs instead of |
| 272 | addresses. */ |
| 273 | howto = bfd_reloc_type_lookup (link_info.output_bfd, p->reloc); |
| 274 | if (howto == NULL) |
| 275 | { |
| 276 | if (bfd_link_relocatable (&link_info)) |
| 277 | { |
| 278 | einfo (_("%X%P: %s does not support reloc %s for set %s\n"), |
| 279 | bfd_get_target (link_info.output_bfd), |
| 280 | bfd_get_reloc_code_name (p->reloc), |
| 281 | p->h->root.string); |
| 282 | continue; |
| 283 | } |
| 284 | |
| 285 | /* If this is not a relocatable link, all we need is the |
| 286 | size, which we can get from the input BFD. */ |
| 287 | if (p->elements->section->owner != NULL) |
| 288 | howto = bfd_reloc_type_lookup (p->elements->section->owner, |
| 289 | p->reloc); |
| 290 | if (howto == NULL) |
| 291 | { |
| 292 | /* See PR 20911 for a reproducer. */ |
| 293 | if (p->elements->section->owner == NULL) |
| 294 | einfo (_("%X%P: special section %s does not support reloc %s for set %s\n"), |
| 295 | bfd_section_name (p->elements->section), |
| 296 | bfd_get_reloc_code_name (p->reloc), |
| 297 | p->h->root.string); |
| 298 | else |
| 299 | einfo (_("%X%P: %s does not support reloc %s for set %s\n"), |
| 300 | bfd_get_target (p->elements->section->owner), |
| 301 | bfd_get_reloc_code_name (p->reloc), |
| 302 | p->h->root.string); |
| 303 | continue; |
| 304 | } |
| 305 | } |
| 306 | |
| 307 | reloc_size = bfd_get_reloc_size (howto); |
| 308 | switch (reloc_size) |
| 309 | { |
| 310 | case 1: size = BYTE; break; |
| 311 | case 2: size = SHORT; break; |
| 312 | case 4: size = LONG; break; |
| 313 | case 8: |
| 314 | if (howto->complain_on_overflow == complain_overflow_signed) |
| 315 | size = SQUAD; |
| 316 | else |
| 317 | size = QUAD; |
| 318 | break; |
| 319 | default: |
| 320 | einfo (_("%X%P: unsupported size %d for set %s\n"), |
| 321 | bfd_get_reloc_size (howto), p->h->root.string); |
| 322 | size = LONG; |
| 323 | break; |
| 324 | } |
| 325 | |
| 326 | lang_add_assignment (exp_assign (".", |
| 327 | exp_unop (ALIGN_K, |
| 328 | exp_intop (reloc_size)), |
| 329 | FALSE)); |
| 330 | lang_add_assignment (exp_assign (p->h->root.string, |
| 331 | exp_nameop (NAME, "."), |
| 332 | FALSE)); |
| 333 | lang_add_data (size, exp_intop (p->count)); |
| 334 | |
| 335 | for (e = p->elements; e != NULL; e = e->u.next) |
| 336 | { |
| 337 | if (config.map_file != NULL) |
| 338 | { |
| 339 | int len; |
| 340 | |
| 341 | if (!header_printed) |
| 342 | { |
| 343 | minfo (_("\nSet Symbol\n\n")); |
| 344 | header_printed = TRUE; |
| 345 | } |
| 346 | |
| 347 | minfo ("%s", p->h->root.string); |
| 348 | len = strlen (p->h->root.string); |
| 349 | |
| 350 | if (len >= 19) |
| 351 | { |
| 352 | print_nl (); |
| 353 | len = 0; |
| 354 | } |
| 355 | while (len < 20) |
| 356 | { |
| 357 | print_space (); |
| 358 | ++len; |
| 359 | } |
| 360 | |
| 361 | if (e->name != NULL) |
| 362 | minfo ("%pT\n", e->name); |
| 363 | else |
| 364 | minfo ("%G\n", e->section->owner, e->section, e->value); |
| 365 | } |
| 366 | |
| 367 | /* Need SEC_KEEP for --gc-sections. */ |
| 368 | if (!bfd_is_abs_section (e->section)) |
| 369 | e->section->flags |= SEC_KEEP; |
| 370 | |
| 371 | if (bfd_link_relocatable (&link_info)) |
| 372 | lang_add_reloc (p->reloc, howto, e->section, e->name, |
| 373 | exp_intop (e->value)); |
| 374 | else |
| 375 | lang_add_data (size, exp_relop (e->section, e->value)); |
| 376 | } |
| 377 | |
| 378 | lang_add_data (size, exp_intop (0)); |
| 379 | } |
| 380 | |
| 381 | pop_stat_ptr (); |
| 382 | } |