1 /* ldctor.c -- constructor support routines 2 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 1998 3 Free Software Foundation, Inc. 4 By Steve Chamberlain <sac@cygnus.com> 5 6 This file is part of GLD, the Gnu Linker. 7 8 GLD is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 2, or (at your option) 11 any later version. 12 13 GLD is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with GLD; see the file COPYING. If not, write to the Free 20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA 21 02111-1307, USA. */ 22 23 #include "bfd.h" 24 #include "sysdep.h" 25 #include "bfdlink.h" 26 27 #include <ctype.h> 28 29 #include "ld.h" 30 #include "ldexp.h" 31 #include "ldlang.h" 32 #include "ldmisc.h" 33 #include "ldgram.h" 34 #include "ldmain.h" 35 #include "ldctor.h" 36 37 static int ctor_prio PARAMS ((const char *)); 38 static int ctor_cmp PARAMS ((const PTR, const PTR)); 39 40 /* The list of statements needed to handle constructors. These are 41 invoked by the command CONSTRUCTORS in the linker script. */ 42 lang_statement_list_type constructor_list; 43 44 /* Whether the constructors should be sorted. Note that this is 45 global for the entire link; we assume that there is only a single 46 CONSTRUCTORS command in the linker script. */ 47 boolean constructors_sorted; 48 49 /* The sets we have seen. */ 50 struct set_info *sets; 51 52 /* Add an entry to a set. H is the entry in the linker hash table. 53 RELOC is the relocation to use for an entry in the set. SECTION 54 and VALUE are the value to add. This is called during the first 55 phase of the link, when we are still gathering symbols together. 56 We just record the information now. The ldctor_find_constructors 57 function will construct the sets. */ 58 59 void 60 ldctor_add_set_entry (h, reloc, name, section, value) 61 struct bfd_link_hash_entry *h; 62 bfd_reloc_code_real_type reloc; 63 const char *name; 64 asection *section; 65 bfd_vma value; 66 { 67 struct set_info *p; 68 struct set_element *e; 69 struct set_element **epp; 70 71 for (p = sets; p != (struct set_info *) NULL; p = p->next) 72 if (p->h == h) 73 break; 74 75 if (p == (struct set_info *) NULL) 76 { 77 p = (struct set_info *) xmalloc (sizeof (struct set_info)); 78 p->next = sets; 79 sets = p; 80 p->h = h; 81 p->reloc = reloc; 82 p->count = 0; 83 p->elements = NULL; 84 } 85 else 86 { 87 if (p->reloc != reloc) 88 { 89 einfo (_("%P%X: Different relocs used in set %s\n"), h->root.string); 90 return; 91 } 92 93 /* Don't permit a set to be constructed from different object 94 file formats. The same reloc may have different results. We 95 actually could sometimes handle this, but the case is 96 unlikely to ever arise. Sometimes constructor symbols are in 97 unusual sections, such as the absolute section--this appears 98 to be the case in Linux a.out--and in such cases we just 99 assume everything is OK. */ 100 if (p->elements != NULL 101 && section->owner != NULL 102 && p->elements->section->owner != NULL 103 && strcmp (bfd_get_target (section->owner), 104 bfd_get_target (p->elements->section->owner)) != 0) 105 { 106 einfo (_("%P%X: Different object file formats composing set %s\n"), 107 h->root.string); 108 return; 109 } 110 } 111 112 e = (struct set_element *) xmalloc (sizeof (struct set_element)); 113 e->next = NULL; 114 e->name = name; 115 e->section = section; 116 e->value = value; 117 118 for (epp = &p->elements; *epp != NULL; epp = &(*epp)->next) 119 ; 120 *epp = e; 121 122 ++p->count; 123 } 124 125 /* Get the priority of a g++ global constructor or destructor from the 126 symbol name. */ 127 128 static int 129 ctor_prio (name) 130 const char *name; 131 { 132 /* The name will look something like _GLOBAL_$I$65535$test02__Fv. 133 There might be extra leading underscores, and the $ characters 134 might be something else. The I might be a D. */ 135 136 while (*name == '_') 137 ++name; 138 139 if (strncmp (name, "GLOBAL_", sizeof "GLOBAL_" - 1) != 0) 140 return -1; 141 142 name += sizeof "GLOBAL_" - 1; 143 144 if (name[0] != name[2]) 145 return -1; 146 if (name[1] != 'I' && name[1] != 'D') 147 return -1; 148 if (! isdigit ((unsigned char) name[3])) 149 return -1; 150 151 return atoi (name + 3); 152 } 153 154 /* This function is used to sort constructor elements by priority. It 155 is called via qsort. */ 156 157 static int 158 ctor_cmp (p1, p2) 159 const PTR p1; 160 const PTR p2; 161 { 162 const struct set_element **pe1 = (const struct set_element **) p1; 163 const struct set_element **pe2 = (const struct set_element **) p2; 164 const char *n1; 165 const char *n2; 166 int prio1; 167 int prio2; 168 169 n1 = (*pe1)->name; 170 if (n1 == NULL) 171 n1 = ""; 172 n2 = (*pe2)->name; 173 if (n2 == NULL) 174 n2 = ""; 175 176 /* We need to sort in reverse order by priority. When two 177 constructors have the same priority, we should maintain their 178 current relative position. */ 179 180 prio1 = ctor_prio (n1); 181 prio2 = ctor_prio (n2); 182 183 /* We sort in reverse order because that is what g++ expects. */ 184 if (prio1 < prio2) 185 return 1; 186 else if (prio1 > prio2) 187 return -1; 188 189 /* Force a stable sort. */ 190 191 if (pe1 < pe2) 192 return -1; 193 else if (pe1 > pe2) 194 return 1; 195 else 196 return 0; 197 } 198 199 /* This function is called after the first phase of the link and 200 before the second phase. At this point all set information has 201 been gathered. We now put the statements to build the sets 202 themselves into constructor_list. */ 203 204 void 205 ldctor_build_sets () 206 { 207 static boolean called; 208 lang_statement_list_type *old; 209 boolean header_printed; 210 struct set_info *p; 211 212 /* The emulation code may call us directly, but we only want to do 213 this once. */ 214 if (called) 215 return; 216 called = true; 217 218 if (constructors_sorted) 219 { 220 for (p = sets; p != NULL; p = p->next) 221 { 222 int c, i; 223 struct set_element *e; 224 struct set_element **array; 225 226 if (p->elements == NULL) 227 continue; 228 229 c = 0; 230 for (e = p->elements; e != NULL; e = e->next) 231 ++c; 232 233 array = (struct set_element **) xmalloc (c * sizeof *array); 234 235 i = 0; 236 for (e = p->elements; e != NULL; e = e->next) 237 { 238 array[i] = e; 239 ++i; 240 } 241 242 qsort (array, c, sizeof *array, ctor_cmp); 243 244 e = array[0]; 245 p->elements = e; 246 for (i = 0; i < c - 1; i++) 247 array[i]->next = array[i + 1]; 248 array[i]->next = NULL; 249 250 free (array); 251 } 252 } 253 254 old = stat_ptr; 255 stat_ptr = &constructor_list; 256 257 lang_list_init (stat_ptr); 258 259 header_printed = false; 260 for (p = sets; p != (struct set_info *) NULL; p = p->next) 261 { 262 struct set_element *e; 263 reloc_howto_type *howto; 264 int reloc_size, size; 265 266 /* If the symbol is defined, we may have been invoked from 267 collect, and the sets may already have been built, so we do 268 not do anything. */ 269 if (p->h->type == bfd_link_hash_defined 270 || p->h->type == bfd_link_hash_defweak) 271 continue; 272 273 /* For each set we build: 274 set: 275 .long number_of_elements 276 .long element0 277 ... 278 .long elementN 279 .long 0 280 except that we use the right size instead of .long. When 281 generating relocateable output, we generate relocs instead of 282 addresses. */ 283 howto = bfd_reloc_type_lookup (output_bfd, p->reloc); 284 if (howto == (reloc_howto_type *) NULL) 285 { 286 if (link_info.relocateable) 287 { 288 einfo (_("%P%X: %s does not support reloc %s for set %s\n"), 289 bfd_get_target (output_bfd), 290 bfd_get_reloc_code_name (p->reloc), 291 p->h->root.string); 292 continue; 293 } 294 295 /* If this is not a relocateable link, all we need is the 296 size, which we can get from the input BFD. */ 297 if (p->elements->section->owner != NULL) 298 howto = bfd_reloc_type_lookup (p->elements->section->owner, 299 p->reloc); 300 if (howto == NULL) 301 { 302 einfo (_("%P%X: %s does not support reloc %s for set %s\n"), 303 bfd_get_target (p->elements->section->owner), 304 bfd_get_reloc_code_name (p->reloc), 305 p->h->root.string); 306 continue; 307 } 308 } 309 310 reloc_size = bfd_get_reloc_size (howto); 311 switch (reloc_size) 312 { 313 case 1: size = BYTE; break; 314 case 2: size = SHORT; break; 315 case 4: size = LONG; break; 316 case 8: 317 if (howto->complain_on_overflow == complain_overflow_signed) 318 size = SQUAD; 319 else 320 size = QUAD; 321 break; 322 default: 323 einfo (_("%P%X: Unsupported size %d for set %s\n"), 324 bfd_get_reloc_size (howto), p->h->root.string); 325 size = LONG; 326 break; 327 } 328 329 lang_add_assignment (exp_assop ('=', ".", 330 exp_unop (ALIGN_K, 331 exp_intop (reloc_size)))); 332 lang_add_assignment (exp_assop ('=', p->h->root.string, 333 exp_nameop (NAME, "."))); 334 lang_add_data (size, exp_intop ((bfd_vma) p->count)); 335 336 for (e = p->elements; e != (struct set_element *) NULL; e = e->next) 337 { 338 if (config.map_file != NULL) 339 { 340 int len; 341 342 if (! header_printed) 343 { 344 minfo (_("\nSet Symbol\n\n")); 345 header_printed = true; 346 } 347 348 minfo ("%s", p->h->root.string); 349 len = strlen (p->h->root.string); 350 351 if (len >= 19) 352 { 353 print_nl (); 354 len = 0; 355 } 356 while (len < 20) 357 { 358 print_space (); 359 ++len; 360 } 361 362 if (e->name != NULL) 363 minfo ("%T\n", e->name); 364 else 365 minfo ("%G\n", e->section->owner, e->section, e->value); 366 } 367 368 /* Need SEC_KEEP for --gc-sections */ 369 if (! bfd_is_abs_section (e->section)) 370 e->section->flags |= SEC_KEEP; 371 372 if (link_info.relocateable) 373 lang_add_reloc (p->reloc, howto, e->section, e->name, 374 exp_intop (e->value)); 375 else 376 lang_add_data (size, exp_relop (e->section, e->value)); 377 } 378 379 lang_add_data (size, exp_intop (0)); 380 } 381 382 stat_ptr = old; 383 } 384