1 /* ELF program property support.
2 Copyright (C) 2017-2018 Free Software Foundation, Inc.
4 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
21 /* GNU program property draft is at:
23 https://github.com/hjl-tools/linux-abi/wiki/property-draft.pdf
31 /* Get a property, allocate a new one if needed. */
34 _bfd_elf_get_property (bfd *abfd, unsigned int type, unsigned int datasz)
36 elf_property_list *p, **lastp;
38 if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
40 /* Never should happen. */
44 /* Keep the property list in order of type. */
45 lastp = &elf_properties (abfd);
46 for (p = *lastp; p; p = p->next)
48 /* Reuse the existing entry. */
49 if (type == p->property.pr_type)
51 if (datasz > p->property.pr_datasz)
53 /* This can happen when mixing 32-bit and 64-bit objects. */
54 p->property.pr_datasz = datasz;
58 else if (type < p->property.pr_type)
62 p = (elf_property_list *) bfd_alloc (abfd, sizeof (*p));
65 _bfd_error_handler (_("%B: out of memory in _bfd_elf_get_property"),
69 memset (p, 0, sizeof (*p));
70 p->property.pr_type = type;
71 p->property.pr_datasz = datasz;
77 /* Parse GNU properties. */
80 _bfd_elf_parse_gnu_properties (bfd *abfd, Elf_Internal_Note *note)
82 const struct elf_backend_data *bed = get_elf_backend_data (abfd);
83 unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
84 bfd_byte *ptr = (bfd_byte *) note->descdata;
85 bfd_byte *ptr_end = ptr + note->descsz;
87 if (note->descsz < 8 || (note->descsz % align_size) != 0)
91 (_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) size: %#lx"),
92 abfd, note->type, note->descsz);
96 while (ptr != ptr_end)
102 if ((size_t) (ptr_end - ptr) < 8)
105 type = bfd_h_get_32 (abfd, ptr);
106 datasz = bfd_h_get_32 (abfd, ptr + 4);
109 if (datasz > (size_t) (ptr_end - ptr))
112 (_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) type (0x%x) datasz: 0x%x"),
113 abfd, note->type, type, datasz);
114 /* Clear all properties. */
115 elf_properties (abfd) = NULL;
119 if (type >= GNU_PROPERTY_LOPROC)
121 if (bed->elf_machine_code == EM_NONE)
123 /* Ignore processor-specific properties with generic ELF
124 target vector. They should be handled by the matching
125 ELF target vector. */
128 else if (type < GNU_PROPERTY_LOUSER
129 && bed->parse_gnu_properties)
131 enum elf_property_kind kind
132 = bed->parse_gnu_properties (abfd, type, ptr, datasz);
133 if (kind == property_corrupt)
135 /* Clear all properties. */
136 elf_properties (abfd) = NULL;
139 else if (kind != property_ignored)
147 case GNU_PROPERTY_STACK_SIZE:
148 if (datasz != align_size)
151 (_("warning: %B: corrupt stack size: 0x%x"),
153 /* Clear all properties. */
154 elf_properties (abfd) = NULL;
157 prop = _bfd_elf_get_property (abfd, type, datasz);
159 prop->u.number = bfd_h_get_64 (abfd, ptr);
161 prop->u.number = bfd_h_get_32 (abfd, ptr);
162 prop->pr_kind = property_number;
165 case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
169 (_("warning: %B: corrupt no copy on protected size: 0x%x"),
171 /* Clear all properties. */
172 elf_properties (abfd) = NULL;
175 prop = _bfd_elf_get_property (abfd, type, datasz);
176 elf_has_no_copy_on_protected (abfd) = TRUE;
177 prop->pr_kind = property_number;
186 (_("warning: %B: unsupported GNU_PROPERTY_TYPE (%ld) type: 0x%x"),
187 abfd, note->type, type);
190 ptr += (datasz + (align_size - 1)) & ~ (align_size - 1);
196 /* Merge GNU property BPROP with APROP. If APROP isn't NULL, return TRUE
197 if APROP is updated. Otherwise, return TRUE if BPROP should be merged
201 elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd,
202 elf_property *aprop, elf_property *bprop)
204 const struct elf_backend_data *bed = get_elf_backend_data (abfd);
205 unsigned int pr_type = aprop != NULL ? aprop->pr_type : bprop->pr_type;
207 if (bed->merge_gnu_properties != NULL
208 && pr_type >= GNU_PROPERTY_LOPROC
209 && pr_type < GNU_PROPERTY_LOUSER)
210 return bed->merge_gnu_properties (info, abfd, aprop, bprop);
214 case GNU_PROPERTY_STACK_SIZE:
215 if (aprop != NULL && bprop != NULL)
217 if (bprop->u.number > aprop->u.number)
219 aprop->u.number = bprop->u.number;
226 case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
227 /* Return TRUE if APROP is NULL to indicate that BPROP should
229 return aprop == NULL;
232 /* Never should happen. */
239 /* Return the property of TYPE on *LISTP and remove it from *LISTP.
240 Return NULL if not found. */
242 static elf_property *
243 elf_find_and_remove_property (elf_property_list **listp,
246 elf_property_list *list;
248 for (list = *listp; list; list = list->next)
250 if (type == list->property.pr_type)
252 /* Remove this property. */
254 return &list->property;
256 else if (type < list->property.pr_type)
264 /* Merge GNU property list *LISTP with ABFD. */
267 elf_merge_gnu_property_list (struct bfd_link_info *info, bfd *abfd,
268 elf_property_list **listp)
270 elf_property_list *p, **lastp;
273 /* Merge each GNU property in ABFD with the one on *LISTP. */
274 lastp = &elf_properties (abfd);
275 for (p = *lastp; p; p = p->next)
277 pr = elf_find_and_remove_property (listp, p->property.pr_type);
278 /* Pass NULL to elf_merge_gnu_properties for the property which
280 elf_merge_gnu_properties (info, abfd, &p->property, pr);
281 if (p->property.pr_kind == property_remove)
283 /* Remove this property. */
290 /* Merge the remaining properties on *LISTP with ABFD. */
291 for (p = *listp; p != NULL; p = p->next)
292 if (elf_merge_gnu_properties (info, abfd, NULL, &p->property))
294 if (p->property.pr_type == GNU_PROPERTY_NO_COPY_ON_PROTECTED)
295 elf_has_no_copy_on_protected (abfd) = TRUE;
297 pr = _bfd_elf_get_property (abfd, p->property.pr_type,
298 p->property.pr_datasz);
299 /* It must be a new property. */
300 if (pr->pr_kind != property_unknown)
302 /* Add a new property. */
307 /* Set up GNU properties. Return the first relocatable ELF input with
308 GNU properties if found. Otherwise, return NULL. */
311 _bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info)
313 bfd *abfd, *first_pbfd = NULL;
314 elf_property_list *list;
316 bfd_boolean has_properties = FALSE;
317 const struct elf_backend_data *bed
318 = get_elf_backend_data (info->output_bfd);
319 unsigned int elfclass = bed->s->elfclass;
320 int elf_machine_code = bed->elf_machine_code;
322 /* Find the first relocatable ELF input with GNU properties. */
323 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
324 if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
325 && (abfd->flags & DYNAMIC) == 0
326 && elf_properties (abfd) != NULL)
328 has_properties = TRUE;
330 /* Ignore GNU properties from ELF objects with different machine
331 code or class. Also skip objects without a GNU_PROPERTY note
333 if ((elf_machine_code
334 == get_elf_backend_data (abfd)->elf_machine_code)
336 == get_elf_backend_data (abfd)->s->elfclass)
337 && bfd_get_section_by_name (abfd,
338 NOTE_GNU_PROPERTY_SECTION_NAME) != NULL
341 /* Keep .note.gnu.property section in FIRST_PBFD. */
347 /* Do nothing if there is no .note.gnu.property section. */
351 /* Merge .note.gnu.property sections. */
352 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
353 if (abfd != first_pbfd && (abfd->flags & DYNAMIC) == 0)
355 elf_property_list *null_ptr = NULL;
356 elf_property_list **listp = &null_ptr;
358 /* Merge .note.gnu.property section in relocatable ELF input. */
359 if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
361 list = elf_properties (abfd);
363 /* Ignore GNU properties from ELF objects with different
367 == get_elf_backend_data (abfd)->elf_machine_code))
368 listp = &elf_properties (abfd);
373 /* Merge properties with FIRST_PBFD. FIRST_PBFD can be NULL
374 when all properties are from ELF objects with different
375 machine code or class. */
376 if (first_pbfd != NULL)
377 elf_merge_gnu_property_list (info, first_pbfd, listp);
381 /* Discard the .note.gnu.property section in this bfd. */
382 sec = bfd_get_section_by_name (abfd,
383 NOTE_GNU_PROPERTY_SECTION_NAME);
385 sec->output_section = bfd_abs_section_ptr;
389 /* Rewrite .note.gnu.property section so that GNU properties are
390 always sorted by type even if input GNU properties aren't sorted. */
391 if (first_pbfd != NULL)
396 Elf_External_Note *e_note;
397 unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
399 sec = bfd_get_section_by_name (first_pbfd,
400 NOTE_GNU_PROPERTY_SECTION_NAME);
401 BFD_ASSERT (sec != NULL);
403 /* Update stack size in .note.gnu.property with -z stack-size=N
405 if (info->stacksize > 0)
408 bfd_vma stacksize = info->stacksize;
410 p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_STACK_SIZE,
412 if (p->pr_kind == property_unknown)
414 /* Create GNU_PROPERTY_STACK_SIZE. */
415 p->u.number = stacksize;
416 p->pr_kind = property_number;
418 else if (stacksize > p->u.number)
419 p->u.number = stacksize;
421 else if (elf_properties (first_pbfd) == NULL)
423 /* Discard .note.gnu.property section if all properties have
425 sec->output_section = bfd_abs_section_ptr;
429 /* Compute the section size. */
430 descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
431 descsz = (descsz + 3) & -(unsigned int) 4;
433 for (list = elf_properties (first_pbfd);
437 /* There are 4 byte type + 4 byte datasz for each property. */
438 size += 4 + 4 + list->property.pr_datasz;
439 /* Align each property. */
440 size = (size + (align_size - 1)) & ~(align_size - 1);
443 /* Update .note.gnu.property section now. */
445 contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);
447 e_note = (Elf_External_Note *) contents;
448 bfd_h_put_32 (first_pbfd, sizeof "GNU", &e_note->namesz);
449 bfd_h_put_32 (first_pbfd, size - descsz, &e_note->descsz);
450 bfd_h_put_32 (first_pbfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
451 memcpy (e_note->name, "GNU", sizeof "GNU");
454 for (list = elf_properties (first_pbfd);
458 /* There are 4 byte type + 4 byte datasz for each property. */
459 bfd_h_put_32 (first_pbfd, list->property.pr_type,
461 bfd_h_put_32 (first_pbfd, list->property.pr_datasz,
462 contents + size + 4);
465 /* Write out property value. */
466 switch (list->property.pr_kind)
468 case property_number:
469 switch (list->property.pr_datasz)
472 /* Never should happen. */
479 bfd_h_put_32 (first_pbfd, list->property.u.number,
484 bfd_h_put_64 (first_pbfd, list->property.u.number,
491 /* Never should happen. */
494 size += list->property.pr_datasz;
496 /* Align each property. */
497 size = (size + (align_size - 1)) & ~ (align_size - 1);
500 /* Cache the section contents for elf_link_input_bfd. */
501 elf_section_data (sec)->this_hdr.contents = contents;
503 /* If GNU_PROPERTY_NO_COPY_ON_PROTECTED is set, protected data
504 symbol is defined in the shared object. */
505 if (elf_has_no_copy_on_protected (first_pbfd))
506 info->extern_protected_data = FALSE;