ld/emultempl/mmo.em

   1 # This shell script emits a C file. -*- C -*-
   2 #   Copyright (C) 2001-2015 Free Software Foundation, Inc.
   3 #
   4 # This file is part of the GNU Binutils.
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 3 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program; if not, write to the Free Software
  18 # Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  19 # MA 02110-1301, USA.
  20 #
  21
  22 # This file is sourced from generic.em.
  23
  24 fragment <<EOF
  25 /* Need to have this macro defined before mmix-elfnmmo, which uses the
  26    name for the before_allocation function, defined in ldemul.c (for
  27    the mmo "emulation") or in elf32.em (for the elf64mmix
  28    "emulation").  */
  29 #define gldmmo_before_allocation before_allocation_default
  30
  31 /* We include this header *not* because we expect to handle ELF here
  32    but because we re-use the map_segments function in elf-generic.em,
  33    a file which is rightly somewhat ELF-centric.  But this is only to
  34    get a weird testcase right; ld-mmix/bpo-22, forcing ELF to be
  35    output from the mmo emulation: -m mmo --oformat elf64-mmix!  */
  36 #include "elf-bfd.h"
  37
  38 static void gld${EMULATION_NAME}_after_allocation (void);
  39 EOF
  40
  41 source_em ${srcdir}/emultempl/elf-generic.em
  42 source_em ${srcdir}/emultempl/mmix-elfnmmo.em
  43
  44 fragment <<EOF
  45
  46 /* Place an orphan section.  We use this to put random SEC_CODE or
  47    SEC_READONLY sections right after MMO_TEXT_SECTION_NAME.  Much borrowed
  48    from elf32.em.  */
  49
  50 static lang_output_section_statement_type *
  51 mmo_place_orphan (asection *s,
  52                   const char *secname,
  53                   int constraint ATTRIBUTE_UNUSED)
  54 {
  55   static struct
  56   {
  57     flagword nonzero_flags;
  58     struct orphan_save orphansave;
  59   } holds[] =
  60       {
  61         {
  62           SEC_CODE | SEC_READONLY,
  63           {
  64             MMO_TEXT_SECTION_NAME,
  65             SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE,
  66             0, 0, 0, 0
  67           }
  68         },
  69         {
  70           SEC_LOAD | SEC_DATA,
  71           {
  72             MMO_DATA_SECTION_NAME,
  73             SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_DATA,
  74             0, 0, 0, 0
  75           }
  76         },
  77         {
  78           SEC_ALLOC,
  79           {
  80             ".bss",
  81             SEC_ALLOC,
  82             0, 0, 0, 0
  83           }
  84         }
  85       };
  86
  87   struct orphan_save *place = NULL;
  88   lang_output_section_statement_type *after;
  89   lang_output_section_statement_type *os;
  90   size_t i;
  91
  92   /* We have nothing to say for anything other than a final link or
  93      for sections that are excluded.  */
  94   if (bfd_link_relocatable (&link_info)
  95       || (s->flags & SEC_EXCLUDE) != 0)
  96     return NULL;
  97
  98   os = lang_output_section_find (secname);
  99
 100   /* We have an output section by this name.  Place the section inside it
 101      (regardless of whether the linker script lists it as input).  */
 102   if (os != NULL)
 103     {
 104       lang_add_section (&os->children, s, NULL, os);
 105       return os;
 106     }
 107
 108   /* Check for matching section type flags for sections we care about.
 109      A section without contents can have SEC_LOAD == 0, but we still
 110      want it attached to a sane section so the symbols appear as
 111      expected.  */
 112   if ((s->flags & (SEC_ALLOC | SEC_READONLY)) != SEC_READONLY)
 113     for (i = 0; i < sizeof (holds) / sizeof (holds[0]); i++)
 114       if ((s->flags & holds[i].nonzero_flags) != 0)
 115         {
 116           place = &holds[i].orphansave;
 117           if (place->os == NULL)
 118             place->os = lang_output_section_find (place->name);
 119           break;
 120         }
 121
 122   if (place == NULL)
 123     {
 124       /* For other combinations, we have to give up, except we make
 125          sure not to place the orphan section after the
 126          linker-generated register section; that'd make it continue
 127          the reg section and we never want that to happen for orphan
 128          sections.  */
 129       lang_output_section_statement_type *before;
 130       lang_output_section_statement_type *lookup;
 131       static struct orphan_save hold_nonreg =
 132         {
 133           NULL,
 134           SEC_READONLY,
 135           0, 0, 0, 0
 136         };
 137
 138       if (hold_nonreg.os == NULL)
 139         {
 140           before = lang_output_section_find (MMIX_REG_CONTENTS_SECTION_NAME);
 141
 142           /* If we have no such section, all fine; we don't care where
 143              it's placed.  */
 144           if (before == NULL)
 145             return NULL;
 146
 147           /* We have to find the oss before this one, so we can use that as
 148              "after".  */
 149           for (lookup = &lang_output_section_statement.head->output_section_statement;
 150                lookup != NULL && lookup->next != before;
 151                lookup = lookup->next)
 152             ;
 153
 154           hold_nonreg.os = lookup;
 155         }
 156
 157       place = &hold_nonreg;
 158     }
 159
 160   after = place->os;
 161   if (after == NULL)
 162     return NULL;
 163
 164   /* If there's an output section by *this* name, we'll use it, regardless
 165      of actual section flags, in contrast to what's done in elf32.em.  */
 166   os = lang_insert_orphan (s, secname, 0, after, place, NULL, NULL);
 167
 168   return os;
 169 }
 170
 171 /* Remove the spurious settings of SEC_RELOC that make it to the output at
 172    link time.  We are as confused as elflink.h:elf_bfd_final_link, and
 173    paper over the bug similarly.  */
 174
 175 static void
 176 mmo_wipe_sec_reloc_flag (bfd *abfd, asection *sec, void *ptr ATTRIBUTE_UNUSED)
 177 {
 178   bfd_set_section_flags (abfd, sec,
 179                          bfd_get_section_flags (abfd, sec) & ~SEC_RELOC);
 180 }
 181
 182 /* Iterate with bfd_map_over_sections over mmo_wipe_sec_reloc_flag... */
 183
 184 static void
 185 gld${EMULATION_NAME}_after_allocation (void)
 186 {
 187   bfd_map_over_sections (link_info.output_bfd, mmo_wipe_sec_reloc_flag, NULL);
 188   gld${EMULATION_NAME}_map_segments (FALSE);
 189 }
 190 \f
 191 /* To get on-demand global register allocation right, we need to parse the
 192    relocs, like what happens when linking to ELF.  It needs to be done
 193    before all input sections are supposed to be present.  When linking to
 194    ELF, it's done when reading symbols.  When linking to mmo, we do it
 195    when all input files are seen, which is equivalent.  */
 196
 197 static void
 198 mmo_after_open (void)
 199 {
 200   /* When there's a mismatch between the output format and the emulation
 201      (using weird combinations like "-m mmo --oformat elf64-mmix" for
 202      example), we'd count relocs twice because they'd also be counted
 203      along the usual route for ELF-only linking, which would lead to an
 204      internal accounting error.  */
 205   if (bfd_get_flavour (link_info.output_bfd) != bfd_target_elf_flavour)
 206     {
 207       LANG_FOR_EACH_INPUT_STATEMENT (is)
 208         {
 209           if (bfd_get_flavour (is->the_bfd) == bfd_target_elf_flavour
 210               && !_bfd_mmix_check_all_relocs (is->the_bfd, &link_info))
 211             einfo ("%X%P: Internal problems scanning %B after opening it",
 212                    is->the_bfd);
 213         }
 214     }
 215   after_open_default ();
 216 }
 217 EOF
 218
 219 LDEMUL_PLACE_ORPHAN=mmo_place_orphan
 220 LDEMUL_AFTER_OPEN=mmo_after_open