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  1. /* ldctor.c -- constructor support routines
  2.    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
  3.    2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011
  4.    Free Software Foundation, Inc.
  5.    By Steve Chamberlain <sac@cygnus.com>
  6.  
  7.    This file is part of the GNU Binutils.
  8.  
  9.    This program is free software; you can redistribute it and/or modify
  10.    it under the terms of the GNU General Public License as published by
  11.    the Free Software Foundation; either version 3 of the License, or
  12.    (at your option) any later version.
  13.  
  14.    This program is distributed in the hope that it will be useful,
  15.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17.    GNU General Public License for more details.
  18.  
  19.    You should have received a copy of the GNU General Public License
  20.    along with this program; if not, write to the Free Software
  21.    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  22.    MA 02110-1301, USA.  */
  23.  
  24. #include "sysdep.h"
  25. #include "bfd.h"
  26. #include "bfdlink.h"
  27. #include "safe-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. /* The list of statements needed to handle constructors.  These are
  38.    invoked by the command CONSTRUCTORS in the linker script.  */
  39. lang_statement_list_type constructor_list;
  40.  
  41. /* Whether the constructors should be sorted.  Note that this is
  42.    global for the entire link; we assume that there is only a single
  43.    CONSTRUCTORS command in the linker script.  */
  44. bfd_boolean constructors_sorted;
  45.  
  46. /* The sets we have seen.  */
  47. struct set_info *sets;
  48.  
  49. /* Add an entry to a set.  H is the entry in the linker hash table.
  50.    RELOC is the relocation to use for an entry in the set.  SECTION
  51.    and VALUE are the value to add.  This is called during the first
  52.    phase of the link, when we are still gathering symbols together.
  53.    We just record the information now.  The ldctor_build_sets
  54.    function will construct the sets.  */
  55.  
  56. void
  57. ldctor_add_set_entry (struct bfd_link_hash_entry *h,
  58.                       bfd_reloc_code_real_type reloc,
  59.                       const char *name,
  60.                       asection *section,
  61.                       bfd_vma value)
  62. {
  63.   struct set_info *p;
  64.   struct set_element *e;
  65.   struct set_element **epp;
  66.  
  67.   for (p = sets; p != NULL; p = p->next)
  68.     if (p->h == h)
  69.       break;
  70.  
  71.   if (p == NULL)
  72.     {
  73.       p = (struct set_info *) xmalloc (sizeof (struct set_info));
  74.       p->next = sets;
  75.       sets = p;
  76.       p->h = h;
  77.       p->reloc = reloc;
  78.       p->count = 0;
  79.       p->elements = NULL;
  80.     }
  81.   else
  82.     {
  83.       if (p->reloc != reloc)
  84.         {
  85.           einfo (_("%P%X: Different relocs used in set %s\n"),
  86.                  h->root.string);
  87.           return;
  88.         }
  89.  
  90.       /* Don't permit a set to be constructed from different object
  91.          file formats.  The same reloc may have different results.  We
  92.          actually could sometimes handle this, but the case is
  93.          unlikely to ever arise.  Sometimes constructor symbols are in
  94.          unusual sections, such as the absolute section--this appears
  95.          to be the case in Linux a.out--and in such cases we just
  96.          assume everything is OK.  */
  97.       if (p->elements != NULL
  98.           && section->owner != NULL
  99.           && p->elements->section->owner != NULL
  100.           && strcmp (bfd_get_target (section->owner),
  101.                      bfd_get_target (p->elements->section->owner)) != 0)
  102.         {
  103.           einfo (_("%P%X: Different object file formats composing set %s\n"),
  104.                  h->root.string);
  105.           return;
  106.         }
  107.     }
  108.  
  109.   e = (struct set_element *) xmalloc (sizeof (struct set_element));
  110.   e->next = NULL;
  111.   e->name = name;
  112.   e->section = section;
  113.   e->value = value;
  114.  
  115.   for (epp = &p->elements; *epp != NULL; epp = &(*epp)->next)
  116.     ;
  117.   *epp = e;
  118.  
  119.   ++p->count;
  120. }
  121.  
  122. /* Get the priority of a g++ global constructor or destructor from the
  123.    symbol name.  */
  124.  
  125. static int
  126. ctor_prio (const char *name)
  127. {
  128.   /* The name will look something like _GLOBAL_$I$65535$test02__Fv.
  129.      There might be extra leading underscores, and the $ characters
  130.      might be something else.  The I might be a D.  */
  131.  
  132.   while (*name == '_')
  133.     ++name;
  134.  
  135.   if (! CONST_STRNEQ (name, "GLOBAL_"))
  136.     return -1;
  137.  
  138.   name += sizeof "GLOBAL_" - 1;
  139.  
  140.   if (name[0] != name[2])
  141.     return -1;
  142.   if (name[1] != 'I' && name[1] != 'D')
  143.     return -1;
  144.   if (! ISDIGIT (name[3]))
  145.     return -1;
  146.  
  147.   return atoi (name + 3);
  148. }
  149.  
  150. /* This function is used to sort constructor elements by priority.  It
  151.    is called via qsort.  */
  152.  
  153. static int
  154. ctor_cmp (const void *p1, const void *p2)
  155. {
  156.   const struct set_element * const *pe1 =
  157.       (const struct set_element * const *) p1;
  158.   const struct set_element * const *pe2 =
  159.       (const struct set_element * const *) p2;
  160.   const char *n1;
  161.   const char *n2;
  162.   int prio1;
  163.   int prio2;
  164.  
  165.   n1 = (*pe1)->name;
  166.   if (n1 == NULL)
  167.     n1 = "";
  168.   n2 = (*pe2)->name;
  169.   if (n2 == NULL)
  170.     n2 = "";
  171.  
  172.   /* We need to sort in reverse order by priority.  When two
  173.      constructors have the same priority, we should maintain their
  174.      current relative position.  */
  175.  
  176.   prio1 = ctor_prio (n1);
  177.   prio2 = ctor_prio (n2);
  178.  
  179.   /* We sort in reverse order because that is what g++ expects.  */
  180.   if (prio1 < prio2)
  181.     return 1;
  182.   else if (prio1 > prio2)
  183.     return -1;
  184.  
  185.   /* Force a stable sort.  */
  186.  
  187.   if (pe1 < pe2)
  188.     return -1;
  189.   else if (pe1 > pe2)
  190.     return 1;
  191.   else
  192.     return 0;
  193. }
  194.  
  195. /* This function is called after the first phase of the link and
  196.    before the second phase.  At this point all set information has
  197.    been gathered.  We now put the statements to build the sets
  198.    themselves into constructor_list.  */
  199.  
  200. void
  201. ldctor_build_sets (void)
  202. {
  203.   static bfd_boolean called;
  204.   bfd_boolean header_printed;
  205.   struct set_info *p;
  206.  
  207.   /* The emulation code may call us directly, but we only want to do
  208.      this once.  */
  209.   if (called)
  210.     return;
  211.   called = TRUE;
  212.  
  213.   if (constructors_sorted)
  214.     {
  215.       for (p = sets; p != NULL; p = p->next)
  216.         {
  217.           int c, i;
  218.           struct set_element *e;
  219.           struct set_element **array;
  220.  
  221.           if (p->elements == NULL)
  222.             continue;
  223.  
  224.           c = 0;
  225.           for (e = p->elements; e != NULL; e = e->next)
  226.             ++c;
  227.  
  228.           array = (struct set_element **) xmalloc (c * sizeof *array);
  229.  
  230.           i = 0;
  231.           for (e = p->elements; e != NULL; e = e->next)
  232.             {
  233.               array[i] = e;
  234.               ++i;
  235.             }
  236.  
  237.           qsort (array, c, sizeof *array, ctor_cmp);
  238.  
  239.           e = array[0];
  240.           p->elements = e;
  241.           for (i = 0; i < c - 1; i++)
  242.             array[i]->next = array[i + 1];
  243.           array[i]->next = NULL;
  244.  
  245.           free (array);
  246.         }
  247.     }
  248.  
  249.   lang_list_init (&constructor_list);
  250.   push_stat_ptr (&constructor_list);
  251.  
  252.   header_printed = FALSE;
  253.   for (p = sets; p != NULL; p = p->next)
  254.     {
  255.       struct set_element *e;
  256.       reloc_howto_type *howto;
  257.       int reloc_size, size;
  258.  
  259.       /* If the symbol is defined, we may have been invoked from
  260.          collect, and the sets may already have been built, so we do
  261.          not do anything.  */
  262.       if (p->h->type == bfd_link_hash_defined
  263.           || p->h->type == bfd_link_hash_defweak)
  264.         continue;
  265.  
  266.       /* For each set we build:
  267.            set:
  268.              .long number_of_elements
  269.              .long element0
  270.              ...
  271.              .long elementN
  272.              .long 0
  273.          except that we use the right size instead of .long.  When
  274.          generating relocatable output, we generate relocs instead of
  275.          addresses.  */
  276.       howto = bfd_reloc_type_lookup (link_info.output_bfd, p->reloc);
  277.       if (howto == NULL)
  278.         {
  279.           if (link_info.relocatable)
  280.             {
  281.               einfo (_("%P%X: %s does not support reloc %s for set %s\n"),
  282.                      bfd_get_target (link_info.output_bfd),
  283.                      bfd_get_reloc_code_name (p->reloc),
  284.                      p->h->root.string);
  285.               continue;
  286.             }
  287.  
  288.           /* If this is not a relocatable link, all we need is the
  289.              size, which we can get from the input BFD.  */
  290.           if (p->elements->section->owner != NULL)
  291.             howto = bfd_reloc_type_lookup (p->elements->section->owner,
  292.                                            p->reloc);
  293.           if (howto == NULL)
  294.             {
  295.               einfo (_("%P%X: %s does not support reloc %s for set %s\n"),
  296.                      bfd_get_target (p->elements->section->owner),
  297.                      bfd_get_reloc_code_name (p->reloc),
  298.                      p->h->root.string);
  299.               continue;
  300.             }
  301.         }
  302.  
  303.       reloc_size = bfd_get_reloc_size (howto);
  304.       switch (reloc_size)
  305.         {
  306.         case 1: size = BYTE; break;
  307.         case 2: size = SHORT; break;
  308.         case 4: size = LONG; break;
  309.         case 8:
  310.           if (howto->complain_on_overflow == complain_overflow_signed)
  311.             size = SQUAD;
  312.           else
  313.             size = QUAD;
  314.           break;
  315.         default:
  316.           einfo (_("%P%X: Unsupported size %d for set %s\n"),
  317.                  bfd_get_reloc_size (howto), p->h->root.string);
  318.           size = LONG;
  319.           break;
  320.         }
  321.  
  322.       lang_add_assignment (exp_assign (".",
  323.                                        exp_unop (ALIGN_K,
  324.                                                  exp_intop (reloc_size)),
  325.                                        FALSE));
  326.       lang_add_assignment (exp_assign (p->h->root.string,
  327.                                        exp_nameop (NAME, "."),
  328.                                        FALSE));
  329.       lang_add_data (size, exp_intop (p->count));
  330.  
  331.       for (e = p->elements; e != NULL; e = e->next)
  332.         {
  333.           if (config.map_file != NULL)
  334.             {
  335.               int len;
  336.  
  337.               if (! header_printed)
  338.                 {
  339.                   minfo (_("\nSet                 Symbol\n\n"));
  340.                   header_printed = TRUE;
  341.                 }
  342.  
  343.               minfo ("%s", p->h->root.string);
  344.               len = strlen (p->h->root.string);
  345.  
  346.               if (len >= 19)
  347.                 {
  348.                   print_nl ();
  349.                   len = 0;
  350.                 }
  351.               while (len < 20)
  352.                 {
  353.                   print_space ();
  354.                   ++len;
  355.                 }
  356.  
  357.               if (e->name != NULL)
  358.                 minfo ("%T\n", e->name);
  359.               else
  360.                 minfo ("%G\n", e->section->owner, e->section, e->value);
  361.             }
  362.  
  363.           /* Need SEC_KEEP for --gc-sections.  */
  364.           if (! bfd_is_abs_section (e->section))
  365.             e->section->flags |= SEC_KEEP;
  366.  
  367.           if (link_info.relocatable)
  368.             lang_add_reloc (p->reloc, howto, e->section, e->name,
  369.                             exp_intop (e->value));
  370.           else
  371.             lang_add_data (size, exp_relop (e->section, e->value));
  372.         }
  373.  
  374.       lang_add_data (size, exp_intop (0));
  375.     }
  376.  
  377.   pop_stat_ptr ();
  378. }
  379.