ld/ldctor.c

   1 /* ldctor.c -- constructor support routines
   2    Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 2000
   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"),
  90                  h->root.string);
  91           return;
  92         }
  93
  94       /* Don't permit a set to be constructed from different object
  95          file formats.  The same reloc may have different results.  We
  96          actually could sometimes handle this, but the case is
  97          unlikely to ever arise.  Sometimes constructor symbols are in
  98          unusual sections, such as the absolute section--this appears
  99          to be the case in Linux a.out--and in such cases we just
 100          assume everything is OK.  */
 101       if (p->elements != NULL
 102           && section->owner != NULL
 103           && p->elements->section->owner != NULL
 104           && strcmp (bfd_get_target (section->owner),
 105                      bfd_get_target (p->elements->section->owner)) != 0)
 106         {
 107           einfo (_("%P%X: Different object file formats composing set %s\n"),
 108                  h->root.string);
 109           return;
 110         }
 111     }
 112
 113   e = (struct set_element *) xmalloc (sizeof (struct set_element));
 114   e->next = NULL;
 115   e->name = name;
 116   e->section = section;
 117   e->value = value;
 118
 119   for (epp = &p->elements; *epp != NULL; epp = &(*epp)->next)
 120     ;
 121   *epp = e;
 122
 123   ++p->count;
 124 }
 125
 126 /* Get the priority of a g++ global constructor or destructor from the
 127    symbol name.  */
 128
 129 static int
 130 ctor_prio (name)
 131      const char *name;
 132 {
 133   /* The name will look something like _GLOBAL_$I$65535$test02__Fv.
 134      There might be extra leading underscores, and the $ characters
 135      might be something else.  The I might be a D.  */
 136
 137   while (*name == '_')
 138     ++name;
 139
 140   if (strncmp (name, "GLOBAL_", sizeof "GLOBAL_" - 1) != 0)
 141     return -1;
 142
 143   name += sizeof "GLOBAL_" - 1;
 144
 145   if (name[0] != name[2])
 146     return -1;
 147   if (name[1] != 'I' && name[1] != 'D')
 148     return -1;
 149   if (! isdigit ((unsigned char) name[3]))
 150     return -1;
 151
 152   return atoi (name + 3);
 153 }
 154
 155 /* This function is used to sort constructor elements by priority.  It
 156    is called via qsort.  */
 157
 158 static int
 159 ctor_cmp (p1, p2)
 160      const PTR p1;
 161      const PTR p2;
 162 {
 163   const struct set_element **pe1 = (const struct set_element **) p1;
 164   const struct set_element **pe2 = (const struct set_element **) p2;
 165   const char *n1;
 166   const char *n2;
 167   int prio1;
 168   int prio2;
 169
 170   n1 = (*pe1)->name;
 171   if (n1 == NULL)
 172     n1 = "";
 173   n2 = (*pe2)->name;
 174   if (n2 == NULL)
 175     n2 = "";
 176
 177   /* We need to sort in reverse order by priority.  When two
 178      constructors have the same priority, we should maintain their
 179      current relative position.  */
 180
 181   prio1 = ctor_prio (n1);
 182   prio2 = ctor_prio (n2);
 183
 184   /* We sort in reverse order because that is what g++ expects.  */
 185   if (prio1 < prio2)
 186     return 1;
 187   else if (prio1 > prio2)
 188     return -1;
 189
 190   /* Force a stable sort.  */
 191
 192   if (pe1 < pe2)
 193     return -1;
 194   else if (pe1 > pe2)
 195     return 1;
 196   else
 197     return 0;
 198 }
 199
 200 /* This function is called after the first phase of the link and
 201    before the second phase.  At this point all set information has
 202    been gathered.  We now put the statements to build the sets
 203    themselves into constructor_list.  */
 204
 205 void
 206 ldctor_build_sets ()
 207 {
 208   static boolean called;
 209   lang_statement_list_type *old;
 210   boolean header_printed;
 211   struct set_info *p;
 212
 213   /* The emulation code may call us directly, but we only want to do
 214      this once.  */
 215   if (called)
 216     return;
 217   called = true;
 218
 219   if (constructors_sorted)
 220     {
 221       for (p = sets; p != NULL; p = p->next)
 222         {
 223           int c, i;
 224           struct set_element *e;
 225           struct set_element **array;
 226
 227           if (p->elements == NULL)
 228             continue;
 229
 230           c = 0;
 231           for (e = p->elements; e != NULL; e = e->next)
 232             ++c;
 233
 234           array = (struct set_element **) xmalloc (c * sizeof *array);
 235
 236           i = 0;
 237           for (e = p->elements; e != NULL; e = e->next)
 238             {
 239               array[i] = e;
 240               ++i;
 241             }
 242
 243           qsort (array, c, sizeof *array, ctor_cmp);
 244
 245           e = array[0];
 246           p->elements = e;
 247           for (i = 0; i < c - 1; i++)
 248             array[i]->next = array[i + 1];
 249           array[i]->next = NULL;
 250
 251           free (array);
 252         }
 253     }
 254
 255   old = stat_ptr;
 256   stat_ptr = &constructor_list;
 257
 258   lang_list_init (stat_ptr);
 259
 260   header_printed = false;
 261   for (p = sets; p != (struct set_info *) NULL; p = p->next)
 262     {
 263       struct set_element *e;
 264       reloc_howto_type *howto;
 265       int reloc_size, size;
 266
 267       /* If the symbol is defined, we may have been invoked from
 268          collect, and the sets may already have been built, so we do
 269          not do anything.  */
 270       if (p->h->type == bfd_link_hash_defined
 271           || p->h->type == bfd_link_hash_defweak)
 272         continue;
 273
 274       /* For each set we build:
 275            set:
 276              .long number_of_elements
 277              .long element0
 278              ...
 279              .long elementN
 280              .long 0
 281          except that we use the right size instead of .long.  When
 282          generating relocateable output, we generate relocs instead of
 283          addresses.  */
 284       howto = bfd_reloc_type_lookup (output_bfd, p->reloc);
 285       if (howto == (reloc_howto_type *) NULL)
 286         {
 287           if (link_info.relocateable)
 288             {
 289               einfo (_("%P%X: %s does not support reloc %s for set %s\n"),
 290                      bfd_get_target (output_bfd),
 291                      bfd_get_reloc_code_name (p->reloc),
 292                      p->h->root.string);
 293               continue;
 294             }
 295
 296           /* If this is not a relocateable link, all we need is the
 297              size, which we can get from the input BFD.  */
 298           if (p->elements->section->owner != NULL)
 299             howto = bfd_reloc_type_lookup (p->elements->section->owner,
 300                                            p->reloc);
 301           if (howto == NULL)
 302             {
 303               einfo (_("%P%X: %s does not support reloc %s for set %s\n"),
 304                      bfd_get_target (p->elements->section->owner),
 305                      bfd_get_reloc_code_name (p->reloc),
 306                      p->h->root.string);
 307               continue;
 308             }
 309         }
 310
 311       reloc_size = bfd_get_reloc_size (howto);
 312       switch (reloc_size)
 313         {
 314         case 1: size = BYTE; break;
 315         case 2: size = SHORT; break;
 316         case 4: size = LONG; break;
 317         case 8:
 318           if (howto->complain_on_overflow == complain_overflow_signed)
 319             size = SQUAD;
 320           else
 321             size = QUAD;
 322           break;
 323         default:
 324           einfo (_("%P%X: Unsupported size %d for set %s\n"),
 325                  bfd_get_reloc_size (howto), p->h->root.string);
 326           size = LONG;
 327           break;
 328         }
 329
 330       lang_add_assignment (exp_assop ('=', ".",
 331                                       exp_unop (ALIGN_K,
 332                                                 exp_intop (reloc_size))));
 333       lang_add_assignment (exp_assop ('=', p->h->root.string,
 334                                       exp_nameop (NAME, ".")));
 335       lang_add_data (size, exp_intop ((bfd_vma) p->count));
 336
 337       for (e = p->elements; e != (struct set_element *) NULL; e = e->next)
 338         {
 339           if (config.map_file != NULL)
 340             {
 341               int len;
 342
 343               if (! header_printed)
 344                 {
 345                   minfo (_("\nSet                 Symbol\n\n"));
 346                   header_printed = true;
 347                 }
 348
 349               minfo ("%s", p->h->root.string);
 350               len = strlen (p->h->root.string);
 351
 352               if (len >= 19)
 353                 {
 354                   print_nl ();
 355                   len = 0;
 356                 }
 357               while (len < 20)
 358                 {
 359                   print_space ();
 360                   ++len;
 361                 }
 362
 363               if (e->name != NULL)
 364                 minfo ("%T\n", e->name);
 365               else
 366                 minfo ("%G\n", e->section->owner, e->section, e->value);
 367             }
 368
 369           /* Need SEC_KEEP for --gc-sections.  */
 370           if (! bfd_is_abs_section (e->section))
 371             e->section->flags |= SEC_KEEP;
 372
 373           if (link_info.relocateable)
 374             lang_add_reloc (p->reloc, howto, e->section, e->name,
 375                             exp_intop (e->value));
 376           else
 377             lang_add_data (size, exp_relop (e->section, e->value));
 378         }
 379
 380       lang_add_data (size, exp_intop (0));
 381     }
 382
 383   stat_ptr = old;
 384 }