1 /* Stabs in sections linking support.
2 Copyright (C) 1996-2016 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Cygnus Support.
5 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
23 /* This file contains support for linking stabs in sections, as used
29 #include "aout/stab_gnu.h"
30 #include "safe-ctype.h"
32 /* Stabs entries use a 12 byte format:
33 4 byte string table index
35 1 byte stab other field
36 2 byte stab desc field
38 FIXME: This will have to change for a 64 bit object format.
40 The stabs symbols are divided into compilation units. For the
41 first entry in each unit, the type of 0, the value is the length of
42 the string table for this unit, and the desc field is the number of
43 stabs symbols for this unit. */
52 /* A linked list of totals that we have found for a particular header
53 file. A total is a unique identifier for a particular BINCL...EINCL
54 sequence of STABs that can be used to identify duplicate sequences.
55 It consists of three fields, 'sum_chars' which is the sum of all the
56 STABS characters; 'num_chars' which is the number of these charactes
57 and 'symb' which is a buffer of all the symbols in the sequence. This
58 buffer is only checked as a last resort. */
60 struct stab_link_includes_totals
62 struct stab_link_includes_totals *next;
63 bfd_vma sum_chars; /* Accumulated sum of STABS characters. */
64 bfd_vma num_chars; /* Number of STABS characters. */
65 const char* symb; /* The STABS characters themselves. */
68 /* An entry in the header file hash table. */
70 struct stab_link_includes_entry
72 struct bfd_hash_entry root;
73 /* List of totals we have found for this file. */
74 struct stab_link_includes_totals *totals;
77 /* This structure is used to hold a list of N_BINCL symbols, some of
78 which might be converted into N_EXCL symbols. */
82 /* The next symbol to convert. */
83 struct stab_excl_list *next;
84 /* The offset to this symbol in the section contents. */
86 /* The value to use for the symbol. */
88 /* The type of this symbol (N_BINCL or N_EXCL). */
92 /* This structure is stored with each .stab section. */
94 struct stab_section_info
96 /* This is a linked list of N_BINCL symbols which should be
97 converted into N_EXCL symbols. */
98 struct stab_excl_list *excls;
100 /* This is used to map input stab offsets within their sections
101 to output stab offsets, to take into account stabs that have
102 been deleted. If it is NULL, the output offsets are the same
103 as the input offsets, because no stabs have been deleted from
104 this section. Otherwise the i'th entry is the number of
105 bytes of stabs that have been deleted prior to the i'th
107 bfd_size_type *cumulative_skips;
109 /* This is an array of string indices. For each stab symbol, we
110 store the string index here. If a stab symbol should not be
111 included in the final output, the string index is -1. */
112 bfd_size_type stridxs[1];
116 /* The function to create a new entry in the header file hash table. */
118 static struct bfd_hash_entry *
119 stab_link_includes_newfunc (struct bfd_hash_entry *entry,
120 struct bfd_hash_table *table,
123 struct stab_link_includes_entry *ret =
124 (struct stab_link_includes_entry *) entry;
126 /* Allocate the structure if it has not already been allocated by a
129 ret = (struct stab_link_includes_entry *)
130 bfd_hash_allocate (table, sizeof (struct stab_link_includes_entry));
134 /* Call the allocation method of the superclass. */
135 ret = ((struct stab_link_includes_entry *)
136 bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
138 /* Set local fields. */
141 return (struct bfd_hash_entry *) ret;
144 /* This function is called for each input file from the add_symbols
145 pass of the linker. */
148 _bfd_link_section_stabs (bfd *abfd,
149 struct stab_info *sinfo,
151 asection *stabstrsec,
153 bfd_size_type *pstring_offset)
156 bfd_size_type count, amt;
157 struct stab_section_info *secinfo;
158 bfd_byte *stabbuf = NULL;
159 bfd_byte *stabstrbuf = NULL;
160 bfd_byte *sym, *symend;
161 bfd_size_type stroff, next_stroff, skip;
162 bfd_size_type *pstridx;
164 if (stabsec->size == 0
165 || stabstrsec->size == 0)
166 /* This file does not contain stabs debugging information. */
169 if (stabsec->size % STABSIZE != 0)
170 /* Something is wrong with the format of these stab symbols.
171 Don't try to optimize them. */
174 if ((stabstrsec->flags & SEC_RELOC) != 0)
175 /* We shouldn't see relocations in the strings, and we aren't
176 prepared to handle them. */
179 if (bfd_is_abs_section (stabsec->output_section)
180 || bfd_is_abs_section (stabstrsec->output_section))
181 /* At least one of the sections is being discarded from the
182 link, so we should just ignore them. */
187 if (sinfo->stabstr == NULL)
191 /* Initialize the stabs information we need to keep track of. */
193 sinfo->strings = _bfd_stringtab_init ();
194 if (sinfo->strings == NULL)
196 /* Make sure the first byte is zero. */
197 (void) _bfd_stringtab_add (sinfo->strings, "", TRUE, TRUE);
198 if (! bfd_hash_table_init (&sinfo->includes,
199 stab_link_includes_newfunc,
200 sizeof (struct stab_link_includes_entry)))
202 flags = (SEC_HAS_CONTENTS | SEC_READONLY | SEC_DEBUGGING
203 | SEC_LINKER_CREATED);
204 sinfo->stabstr = bfd_make_section_anyway_with_flags (abfd, ".stabstr",
206 if (sinfo->stabstr == NULL)
210 /* Initialize the information we are going to store for this .stab
212 count = stabsec->size / STABSIZE;
214 amt = sizeof (struct stab_section_info);
215 amt += (count - 1) * sizeof (bfd_size_type);
216 *psecinfo = bfd_alloc (abfd, amt);
217 if (*psecinfo == NULL)
220 secinfo = (struct stab_section_info *) *psecinfo;
221 secinfo->excls = NULL;
222 stabsec->rawsize = stabsec->size;
223 secinfo->cumulative_skips = NULL;
224 memset (secinfo->stridxs, 0, (size_t) count * sizeof (bfd_size_type));
226 /* Read the stabs information from abfd. */
227 if (!bfd_malloc_and_get_section (abfd, stabsec, &stabbuf)
228 || !bfd_malloc_and_get_section (abfd, stabstrsec, &stabstrbuf))
231 /* Look through the stabs symbols, work out the new string indices,
232 and identify N_BINCL symbols which can be eliminated. */
234 /* The stabs sections can be split when
235 -split-by-reloc/-split-by-file is used. We must keep track of
236 each stab section's place in the single concatenated string
238 next_stroff = pstring_offset ? *pstring_offset : 0;
241 symend = stabbuf + stabsec->size;
242 for (sym = stabbuf, pstridx = secinfo->stridxs;
244 sym += STABSIZE, ++pstridx)
246 bfd_size_type symstroff;
251 /* This symbol has already been handled by an N_BINCL pass. */
258 /* Special type 0 stabs indicate the offset to the next
259 string table. We only copy the very first one. */
260 stroff = next_stroff;
261 next_stroff += bfd_get_32 (abfd, sym + 8);
263 *pstring_offset = next_stroff;
266 *pstridx = (bfd_size_type) -1;
273 /* Store the string in the hash table, and record the index. */
274 symstroff = stroff + bfd_get_32 (abfd, sym + STRDXOFF);
275 if (symstroff >= stabstrsec->size)
278 (_("%B(%A+0x%lx): Stabs entry has invalid string index."),
279 abfd, stabsec, (long) (sym - stabbuf));
280 bfd_set_error (bfd_error_bad_value);
283 string = (char *) stabstrbuf + symstroff;
284 *pstridx = _bfd_stringtab_add (sinfo->strings, string, TRUE, TRUE);
286 /* An N_BINCL symbol indicates the start of the stabs entries
287 for a header file. We need to scan ahead to the next N_EINCL
288 symbol, ignoring nesting, adding up all the characters in the
289 symbol names, not including the file numbers in types (the
290 first number after an open parenthesis). */
291 if (type == (int) N_BINCL)
300 struct stab_link_includes_entry * incl_entry;
301 struct stab_link_includes_totals * t;
302 struct stab_excl_list * ne;
304 symb = symb_rover = NULL;
305 sum_chars = num_chars = 0;
308 for (incl_sym = sym + STABSIZE;
310 incl_sym += STABSIZE)
314 incl_type = incl_sym[TYPEOFF];
317 else if (incl_type == (int) N_EXCL)
319 else if (incl_type == (int) N_EINCL)
325 else if (incl_type == (int) N_BINCL)
331 str = ((char *) stabstrbuf
333 + bfd_get_32 (abfd, incl_sym + STRDXOFF));
334 for (; *str != '\0'; str++)
336 if (num_chars >= buf_len)
338 buf_len += 32 * 1024;
339 symb = (char *) bfd_realloc_or_free (symb, buf_len);
342 symb_rover = symb + num_chars;
344 * symb_rover ++ = * str;
349 /* Skip the file number. */
351 while (ISDIGIT (*str))
359 BFD_ASSERT (num_chars == (bfd_vma) (symb_rover - symb));
361 /* If we have already included a header file with the same
362 value, then replaced this one with an N_EXCL symbol. */
363 incl_entry = (struct stab_link_includes_entry * )
364 bfd_hash_lookup (&sinfo->includes, string, TRUE, TRUE);
365 if (incl_entry == NULL)
368 for (t = incl_entry->totals; t != NULL; t = t->next)
369 if (t->sum_chars == sum_chars
370 && t->num_chars == num_chars
371 && memcmp (t->symb, symb, num_chars) == 0)
374 /* Record this symbol, so that we can set the value
377 ne = (struct stab_excl_list *) bfd_alloc (abfd, amt);
380 ne->offset = sym - stabbuf;
382 ne->type = (int) N_BINCL;
383 ne->next = secinfo->excls;
388 /* This is the first time we have seen this header file
389 with this set of stabs strings. */
390 t = (struct stab_link_includes_totals *)
391 bfd_hash_allocate (&sinfo->includes, sizeof *t);
394 t->sum_chars = sum_chars;
395 t->num_chars = num_chars;
396 /* Trim data down. */
397 t->symb = symb = (char *) bfd_realloc_or_free (symb, num_chars);
398 t->next = incl_entry->totals;
399 incl_entry->totals = t;
403 bfd_size_type *incl_pstridx;
405 /* We have seen this header file before. Tell the final
406 pass to change the type to N_EXCL. */
407 ne->type = (int) N_EXCL;
409 /* Free off superfluous symbols. */
412 /* Mark the skipped symbols. */
415 for (incl_sym = sym + STABSIZE, incl_pstridx = pstridx + 1;
417 incl_sym += STABSIZE, ++incl_pstridx)
421 incl_type = incl_sym[TYPEOFF];
423 if (incl_type == (int) N_EINCL)
427 *incl_pstridx = (bfd_size_type) -1;
433 else if (incl_type == (int) N_BINCL)
435 else if (incl_type == (int) N_EXCL)
436 /* Keep existing exclusion marks. */
440 *incl_pstridx = (bfd_size_type) -1;
453 /* We need to set the section sizes such that the linker will
454 compute the output section sizes correctly. We set the .stab
455 size to not include the entries we don't want. We set
456 SEC_EXCLUDE for the .stabstr section, so that it will be dropped
457 from the link. We record the size of the strtab in the first
458 .stabstr section we saw, and make sure we don't set SEC_EXCLUDE
460 stabsec->size = (count - skip) * STABSIZE;
461 if (stabsec->size == 0)
462 stabsec->flags |= SEC_EXCLUDE | SEC_KEEP;
463 stabstrsec->flags |= SEC_EXCLUDE | SEC_KEEP;
464 sinfo->stabstr->size = _bfd_stringtab_size (sinfo->strings);
466 /* Calculate the `cumulative_skips' array now that stabs have been
467 deleted for this section. */
471 bfd_size_type i, offset;
472 bfd_size_type *pskips;
474 amt = count * sizeof (bfd_size_type);
475 secinfo->cumulative_skips = (bfd_size_type *) bfd_alloc (abfd, amt);
476 if (secinfo->cumulative_skips == NULL)
479 pskips = secinfo->cumulative_skips;
480 pstridx = secinfo->stridxs;
483 for (i = 0; i < count; i++, pskips++, pstridx++)
486 if (*pstridx == (bfd_size_type) -1)
490 BFD_ASSERT (offset != 0);
498 if (stabstrbuf != NULL)
503 /* This function is called for each input file before the stab
504 section is relocated. It discards stab entries for discarded
505 functions and variables. The function returns TRUE iff
506 any entries have been deleted.
510 _bfd_discard_section_stabs (bfd *abfd,
513 bfd_boolean (*reloc_symbol_deleted_p) (bfd_vma, void *),
516 bfd_size_type count, amt;
517 struct stab_section_info *secinfo;
518 bfd_byte *stabbuf = NULL;
519 bfd_byte *sym, *symend;
521 bfd_size_type *pstridx;
524 if (stabsec->size == 0)
525 /* This file does not contain stabs debugging information. */
528 if (stabsec->size % STABSIZE != 0)
529 /* Something is wrong with the format of these stab symbols.
530 Don't try to optimize them. */
533 if ((stabsec->output_section != NULL
534 && bfd_is_abs_section (stabsec->output_section)))
535 /* At least one of the sections is being discarded from the
536 link, so we should just ignore them. */
539 /* We should have initialized our data in _bfd_link_section_stabs.
540 If there was some bizarre error reading the string sections, though,
541 we might not have. Bail rather than asserting. */
542 if (psecinfo == NULL)
545 count = stabsec->rawsize / STABSIZE;
546 secinfo = (struct stab_section_info *) psecinfo;
548 /* Read the stabs information from abfd. */
549 if (!bfd_malloc_and_get_section (abfd, stabsec, &stabbuf))
552 /* Look through the stabs symbols and discard any information for
553 discarded functions. */
557 symend = stabbuf + stabsec->rawsize;
558 for (sym = stabbuf, pstridx = secinfo->stridxs;
560 sym += STABSIZE, ++pstridx)
564 if (*pstridx == (bfd_size_type) -1)
565 /* This stab was deleted in a previous pass. */
570 if (type == (int) N_FUN)
572 int strx = bfd_get_32 (abfd, sym + STRDXOFF);
585 if ((*reloc_symbol_deleted_p) (sym + VALOFF - stabbuf, cookie))
594 else if (deleting == -1)
596 /* Outside of a function. Check for deleted variables. */
597 if (type == (int) N_STSYM || type == (int) N_LCSYM)
598 if ((*reloc_symbol_deleted_p) (sym + VALOFF - stabbuf, cookie))
603 /* We should also check for N_GSYM entries which reference a
604 deleted global, but those are less harmful to debuggers
605 and would require parsing the stab strings. */
612 /* Shrink the stabsec as needed. */
613 stabsec->size -= skip * STABSIZE;
614 if (stabsec->size == 0)
615 stabsec->flags |= SEC_EXCLUDE | SEC_KEEP;
617 /* Recalculate the `cumulative_skips' array now that stabs have been
618 deleted for this section. */
622 bfd_size_type i, offset;
623 bfd_size_type *pskips;
625 if (secinfo->cumulative_skips == NULL)
627 amt = count * sizeof (bfd_size_type);
628 secinfo->cumulative_skips = (bfd_size_type *) bfd_alloc (abfd, amt);
629 if (secinfo->cumulative_skips == NULL)
633 pskips = secinfo->cumulative_skips;
634 pstridx = secinfo->stridxs;
637 for (i = 0; i < count; i++, pskips++, pstridx++)
640 if (*pstridx == (bfd_size_type) -1)
644 BFD_ASSERT (offset != 0);
655 /* Write out the stab section. This is called with the relocated
659 _bfd_write_section_stabs (bfd *output_bfd,
660 struct stab_info *sinfo,
665 struct stab_section_info *secinfo;
666 struct stab_excl_list *e;
667 bfd_byte *sym, *tosym, *symend;
668 bfd_size_type *pstridx;
670 secinfo = (struct stab_section_info *) *psecinfo;
673 return bfd_set_section_contents (output_bfd, stabsec->output_section,
674 contents, stabsec->output_offset,
677 /* Handle each N_BINCL entry. */
678 for (e = secinfo->excls; e != NULL; e = e->next)
682 BFD_ASSERT (e->offset < stabsec->rawsize);
683 excl_sym = contents + e->offset;
684 bfd_put_32 (output_bfd, e->val, excl_sym + VALOFF);
685 excl_sym[TYPEOFF] = e->type;
688 /* Copy over all the stabs symbols, omitting the ones we don't want,
689 and correcting the string indices for those we do want. */
691 symend = contents + stabsec->rawsize;
692 for (sym = contents, pstridx = secinfo->stridxs;
694 sym += STABSIZE, ++pstridx)
696 if (*pstridx != (bfd_size_type) -1)
699 memcpy (tosym, sym, STABSIZE);
700 bfd_put_32 (output_bfd, *pstridx, tosym + STRDXOFF);
702 if (sym[TYPEOFF] == 0)
704 /* This is the header symbol for the stabs section. We
705 don't really need one, since we have merged all the
706 input stabs sections into one, but we generate one
707 for the benefit of readers which expect to see one. */
708 BFD_ASSERT (sym == contents);
709 bfd_put_32 (output_bfd, _bfd_stringtab_size (sinfo->strings),
711 bfd_put_16 (output_bfd,
712 stabsec->output_section->size / STABSIZE - 1,
720 BFD_ASSERT ((bfd_size_type) (tosym - contents) == stabsec->size);
722 return bfd_set_section_contents (output_bfd, stabsec->output_section,
723 contents, (file_ptr) stabsec->output_offset,
727 /* Write out the .stabstr section. */
730 _bfd_write_stab_strings (bfd *output_bfd, struct stab_info *sinfo)
732 if (bfd_is_abs_section (sinfo->stabstr->output_section))
733 /* The section was discarded from the link. */
736 BFD_ASSERT ((sinfo->stabstr->output_offset
737 + _bfd_stringtab_size (sinfo->strings))
738 <= sinfo->stabstr->output_section->size);
740 if (bfd_seek (output_bfd,
741 (file_ptr) (sinfo->stabstr->output_section->filepos
742 + sinfo->stabstr->output_offset),
746 if (! _bfd_stringtab_emit (output_bfd, sinfo->strings))
749 /* We no longer need the stabs information. */
750 _bfd_stringtab_free (sinfo->strings);
751 bfd_hash_table_free (&sinfo->includes);
756 /* Adjust an address in the .stab section. Given OFFSET within
757 STABSEC, this returns the new offset in the adjusted stab section,
758 or -1 if the address refers to a stab which has been removed. */
761 _bfd_stab_section_offset (asection *stabsec,
765 struct stab_section_info *secinfo;
767 secinfo = (struct stab_section_info *) psecinfo;
772 if (offset >= stabsec->rawsize)
773 return offset - stabsec->rawsize + stabsec->size;
775 if (secinfo->cumulative_skips)
779 i = offset / STABSIZE;
781 if (secinfo->stridxs [i] == (bfd_size_type) -1)
784 return offset - secinfo->cumulative_skips [i];