[deliverable/binutils-gdb.git] / bfd / elf-properties.c

/* ELF program property support.
   Copyright (C) 2017 Free Software Foundation, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

/* GNU program property draft is at:

   https://github.com/hjl-tools/linux-abi/wiki/property-draft.pdf
 */

#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "elf-bfd.h"

/* Get a property, allocate a new one if needed.  */

elf_property *
_bfd_elf_get_property (bfd *abfd, unsigned int type, unsigned int datasz)
{
  elf_property_list *p, **lastp;

  if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
    {
      /* Never should happen.  */
      abort ();
    }

  /* Keep the property list in order of type.  */
  lastp = &elf_properties (abfd);
  for (p = *lastp; p; p = p->next)
    {
      /* Reuse the existing entry.  */
      if (type == p->property.pr_type)
	{
	  if (datasz > p->property.pr_datasz)
	    {
	      /* This can happen when mixing 32-bit and 64-bit objects.  */
	      p->property.pr_datasz = datasz;
	    }
	  return &p->property;
	}
      else if (type < p->property.pr_type)
	break;
      lastp = &p->next;
    }
  p = (elf_property_list *) bfd_alloc (abfd, sizeof (*p));
  if (p == NULL)
    {
      _bfd_error_handler (_("%B: out of memory in _bfd_elf_get_property"),
			  abfd);
      _exit (EXIT_FAILURE);
    }
  memset (p, 0, sizeof (*p));
  p->property.pr_type = type;
  p->property.pr_datasz = datasz;
  p->next = *lastp;
  *lastp = p;
  return &p->property;
}

/* Parse GNU properties.  */

bfd_boolean
_bfd_elf_parse_gnu_properties (bfd *abfd, Elf_Internal_Note *note)
{
  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
  unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
  bfd_byte *ptr = (bfd_byte *) note->descdata;
  bfd_byte *ptr_end = ptr + note->descsz;

  if (note->descsz < 8 || (note->descsz % align_size) != 0)
    {
bad_size:
      _bfd_error_handler
	(_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) size: %#lx\n"),
	 abfd, note->type, note->descsz);
      return FALSE;
    }

  while (1)
    {
      unsigned int type = bfd_h_get_32 (abfd, ptr);
      unsigned int datasz = bfd_h_get_32 (abfd, ptr + 4);
      elf_property *prop;

      ptr += 8;

      if ((ptr + datasz) > ptr_end)
	{
	  _bfd_error_handler
	    (_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) type (0x%x) datasz: 0x%x\n"),
	     abfd, note->type, type, datasz);
	  /* Clear all properties.  */
	  elf_properties (abfd) = NULL;
	  return FALSE;
	}

      if (type >= GNU_PROPERTY_LOPROC)
	{
	  if (type < GNU_PROPERTY_LOUSER && bed->parse_gnu_properties)
	    {
	      enum elf_property_kind kind
		= bed->parse_gnu_properties (abfd, type, ptr, datasz);
	      if (kind == property_corrupt)
		{
		  /* Clear all properties.  */
		  elf_properties (abfd) = NULL;
		  return FALSE;
		}
	      else if (kind != property_ignored)
		goto next;
	    }
	}
      else
	{
	  switch (type)
	    {
	    case GNU_PROPERTY_STACK_SIZE:
	      if (datasz != align_size)
		{
		  _bfd_error_handler
		    (_("warning: %B: corrupt stack size: 0x%x\n"),
		     abfd, datasz);
		  /* Clear all properties.  */
		  elf_properties (abfd) = NULL;
		  return FALSE;
		}
	      prop = _bfd_elf_get_property (abfd, type, datasz);
	      if (datasz == 8)
		prop->u.number = bfd_h_get_64 (abfd, ptr);
	      else
		prop->u.number = bfd_h_get_32 (abfd, ptr);
	      prop->pr_kind = property_number;
	      goto next;

	    case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
	      if (datasz != 0)
		{
		  _bfd_error_handler
		    (_("warning: %B: corrupt no copy on protected size: 0x%x\n"),
		     abfd, datasz);
		  /* Clear all properties.  */
		  elf_properties (abfd) = NULL;
		  return FALSE;
		}
	      prop = _bfd_elf_get_property (abfd, type, datasz);
	      prop->pr_kind = property_number;
	      goto next;

	    default:
	      break;
	    }
	}

      _bfd_error_handler
	(_("warning: %B: unsupported GNU_PROPERTY_TYPE (%ld) type: 0x%x\n"),
	 abfd, note->type, type);

next:
      ptr += (datasz + (align_size - 1)) & ~ (align_size - 1);
      if (ptr == ptr_end)
	break;

      if (ptr > (ptr_end - 8))
	goto bad_size;
    }

  return TRUE;
}

/* Merge GNU property BPROP with APROP.  If APROP isn't NULL, return TRUE
   if APROP is updated.  Otherwise, return TRUE if BPROP should be merged
   with ABFD.  */

static bfd_boolean
elf_merge_gnu_properties (bfd *abfd, elf_property *aprop,
			  elf_property *bprop)
{
  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
  unsigned int pr_type = aprop != NULL ? aprop->pr_type : bprop->pr_type;

  if (bed->merge_gnu_properties != NULL
      && pr_type >= GNU_PROPERTY_LOPROC
      && pr_type < GNU_PROPERTY_LOUSER)
    return bed->merge_gnu_properties (abfd, aprop, bprop);

  switch (pr_type)
    {
    case GNU_PROPERTY_STACK_SIZE:
      if (aprop != NULL && bprop != NULL)
	{
	  if (bprop->u.number > aprop->u.number)
	    {
	      aprop->u.number = bprop->u.number;
	      return TRUE;
	    }
	  break;
	}
      /* FALLTHROUGH */

    case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
      /* Return TRUE if APROP is NULL to indicate that BPROP should
	 be added to ABFD.  */
      return aprop == NULL;

    default:
      /* Never should happen.  */
      abort ();
    }

  return FALSE;
}

/* Return the property of TYPE on *LISTP and remove it from *LISTP.
   Return NULL if not found.  */

static elf_property *
elf_find_and_remove_property (elf_property_list **listp,
			      unsigned int type)
{
  elf_property_list *list;

  for (list = *listp; list; list = list->next)
    {
      if (type == list->property.pr_type)
	{
	  /* Remove this property.  */
	  *listp = list->next;
	  return &list->property;
	}
      else if (type < list->property.pr_type)
	break;
      listp = &list->next;
    }

  return NULL;
}

/* Merge GNU property list *LISTP with ABFD.  */

static void
elf_merge_gnu_property_list (bfd *abfd, elf_property_list **listp)
{
  elf_property_list *p, **lastp;
  elf_property *pr;

  /* Merge each GNU property in ABFD with the one on *LISTP.  */
  lastp = &elf_properties (abfd);
  for (p = *lastp; p; p = p->next)
    {
      pr = elf_find_and_remove_property (listp, p->property.pr_type);
      /* Pass NULL to elf_merge_gnu_properties for the property which
	 isn't on *LISTP.  */
      elf_merge_gnu_properties (abfd, &p->property, pr);
      if (p->property.pr_kind == property_remove)
	{
	  /* Remove this property.  */
	  *lastp = p->next;
	  continue;
	}
      lastp = &p->next;
    }

  /* Merge the remaining properties on *LISTP with ABFD.  */
  for (p = *listp; p != NULL; p = p->next)
    if (elf_merge_gnu_properties (abfd, NULL, &p->property))
      {
	pr = _bfd_elf_get_property (abfd, p->property.pr_type,
				    p->property.pr_datasz);
	/* It must be a new property.  */
	if (pr->pr_kind != property_unknown)
	  abort ();
	/* Add a new property.  */
	*pr = p->property;
      }
}

/* Set up GNU properties.  */

void
_bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info)
{
  bfd *abfd, *first_pbfd = NULL;
  elf_property_list *list;
  asection *sec;
  bfd_boolean has_properties = FALSE;
  const struct elf_backend_data *bed
    = get_elf_backend_data (info->output_bfd);
  unsigned int elfclass = bed->s->elfclass;
  int elf_machine_code = bed->elf_machine_code;

  /* Find the first relocatable ELF input with GNU properties.  */
  for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
    if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
	&& bfd_count_sections (abfd) != 0
	&& elf_properties (abfd) != NULL)
      {
	has_properties = TRUE;

	/* Ignore GNU properties from ELF objects with different machine
	   code or class.  */
	if ((elf_machine_code
	     == get_elf_backend_data (abfd)->elf_machine_code)
	    && (elfclass
		== get_elf_backend_data (abfd)->s->elfclass))
	  {
	    /* Keep .note.gnu.property section in FIRST_PBFD.  */
	    first_pbfd = abfd;
	    break;
	  }
      }

  /* Do nothing if there is no .note.gnu.property section.  */
  if (!has_properties)
    return;

  /* Merge .note.gnu.property sections.  */
  for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
    if (abfd != first_pbfd && bfd_count_sections (abfd) != 0)
      {
	elf_property_list *null_ptr = NULL;
	elf_property_list **listp = &null_ptr;

	/* Merge .note.gnu.property section in relocatable ELF input.  */
	if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
	  {
	    list = elf_properties (abfd);

	    /* Ignore GNU properties from ELF objects with different
	       machine code.  */
	    if (list != NULL
		&& (elf_machine_code
		    == get_elf_backend_data (abfd)->elf_machine_code))
	      listp = &elf_properties (abfd);
	  }
	else
	  list = NULL;

	/* Merge properties with FIRST_PBFD.  FIRST_PBFD can be NULL
	   when all properties are from ELF objects with different
	   machine code or class.  */
	if (first_pbfd != NULL)
	  elf_merge_gnu_property_list (first_pbfd, listp);

	if (list != NULL)
	  {
	    /* Discard .note.gnu.property section in the rest inputs.  */
	    sec = bfd_get_section_by_name (abfd,
					   NOTE_GNU_PROPERTY_SECTION_NAME);
	    sec->output_section = bfd_abs_section_ptr;
	  }
      }

  /* Rewrite .note.gnu.property section so that GNU properties are
     always sorted by type even if input GNU properties aren't sorted.  */
  if (first_pbfd != NULL)
    {
      unsigned int size;
      unsigned int descsz;
      bfd_byte *contents;
      Elf_External_Note *e_note;
      unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;

      sec = bfd_get_section_by_name (first_pbfd,
				     NOTE_GNU_PROPERTY_SECTION_NAME);

      /* Update stack size in .note.gnu.property with -z stack-size=N
	 if N > 0.  */
      if (info->stacksize > 0)
	{
	  elf_property *p;
	  bfd_vma stacksize = info->stacksize;

	  p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_STACK_SIZE,
				     align_size);
	  if (p->pr_kind == property_unknown)
	    {
	      /* Create GNU_PROPERTY_STACK_SIZE.  */
	      p->u.number = stacksize;
	      p->pr_kind = property_number;
	    }
	  else if (stacksize > p->u.number)
	    p->u.number = stacksize;
	}
      else if (elf_properties (first_pbfd) == NULL)
	{
	  /* Discard .note.gnu.property section if all properties have
	     been removed.  */
	  sec->output_section = bfd_abs_section_ptr;
	  return;
	}

      /* Compute the section size.  */
      descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
      descsz = (descsz + 3) & -(unsigned int) 4;
      size = descsz;
      for (list = elf_properties (first_pbfd);
	   list != NULL;
	   list = list->next)
	{
	  /* There are 4 byte type + 4 byte datasz for each property.  */
	  size += 4 + 4 + list->property.pr_datasz;
	  /* Align each property.  */
	  size = (size + (align_size - 1)) & ~(align_size - 1);
	}

      /* Update .note.gnu.property section now.  */
      sec->size = size;
      contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);

      e_note = (Elf_External_Note *) contents;
      bfd_h_put_32 (first_pbfd, sizeof "GNU", &e_note->namesz);
      bfd_h_put_32 (first_pbfd, size - descsz, &e_note->descsz);
      bfd_h_put_32 (first_pbfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
      memcpy (e_note->name, "GNU", sizeof "GNU");

      size = descsz;
      for (list = elf_properties (first_pbfd);
	   list != NULL;
	   list = list->next)
	{
	  /* There are 4 byte type + 4 byte datasz for each property.  */
	  bfd_h_put_32 (first_pbfd, list->property.pr_type,
			contents + size);
	  bfd_h_put_32 (first_pbfd, list->property.pr_datasz,
			contents + size + 4);
	  size += 4 + 4;

	  /* Write out property value.  */
	  switch (list->property.pr_kind)
	    {
	    case property_number:
	      switch (list->property.pr_datasz)
		{
		default:
		  /* Never should happen.  */
		  abort ();

		case 0:
		  break;

		case 4:
		  bfd_h_put_32 (first_pbfd, list->property.u.number,
				contents + size);
		  break;

		case 8:
		  bfd_h_put_64 (first_pbfd, list->property.u.number,
				contents + size);
		  break;
		}
	      break;

	    default:
	      /* Never should happen.  */
	      abort ();
	    }
	  size += list->property.pr_datasz;

	  /* Align each property.  */
	  size = (size + (align_size - 1)) & ~ (align_size - 1);
	}

      /* Cache the section contents for elf_link_input_bfd.  */
      elf_section_data (sec)->this_hdr.contents = contents;
    }
}
Commit	Line	Data
46bed679 L	1	/* ELF program property support.
	2	Copyright (C) 2017 Free Software Foundation, Inc.
	3
	4	This file is part of BFD, the Binary File Descriptor library.
	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	/* GNU program property draft is at:
	22
	23	https://github.com/hjl-tools/linux-abi/wiki/property-draft.pdf
	24	*/
	25
	26	#include "sysdep.h"
	27	#include "bfd.h"
	28	#include "libbfd.h"
	29	#include "elf-bfd.h"
	30
	31	/* Get a property, allocate a new one if needed. */
	32
	33	elf_property *
	34	_bfd_elf_get_property (bfd *abfd, unsigned int type, unsigned int datasz)
	35	{
	36	elf_property_list p, *lastp;
	37
	38	if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
	39	{
	40	/* Never should happen. */
	41	abort ();
	42	}
	43
	44	/* Keep the property list in order of type. */
	45	lastp = &elf_properties (abfd);
	46	for (p = *lastp; p; p = p->next)
	47	{
	48	/* Reuse the existing entry. */
	49	if (type == p->property.pr_type)
	50	{
	51	if (datasz > p->property.pr_datasz)
	52	{
	53	/* This can happen when mixing 32-bit and 64-bit objects. */
	54	p->property.pr_datasz = datasz;
	55	}
	56	return &p->property;
	57	}
	58	else if (type < p->property.pr_type)
	59	break;
	60	lastp = &p->next;
	61	}
	62	p = (elf_property_list ) bfd_alloc (abfd, sizeof (p));
	63	if (p == NULL)
	64	{
65	_bfd_error_handler (_("%B: out of memory in _bfd_elf_get_property"),
66	abfd);
67	_exit (EXIT_FAILURE);
68	}
69	memset (p, 0, sizeof (*p));
70	p->property.pr_type = type;
71	p->property.pr_datasz = datasz;
72	p->next = *lastp;
73	*lastp = p;
74	return &p->property;
75	}
76
77	/* Parse GNU properties. */
78
79	bfd_boolean
80	_bfd_elf_parse_gnu_properties (bfd abfd, Elf_Internal_Note note)
81	{
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;
86
87	if (note->descsz < 8 \|\| (note->descsz % align_size) != 0)
88	{
89	bad_size:
90	_bfd_error_handler
91	(_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) size: %#lx\n"),
92	abfd, note->type, note->descsz);
93	return FALSE;
94	}
95
96	while (1)
97	{
98	unsigned int type = bfd_h_get_32 (abfd, ptr);
99	unsigned int datasz = bfd_h_get_32 (abfd, ptr + 4);
100	elf_property *prop;
101
102	ptr += 8;
103
104	if ((ptr + datasz) > ptr_end)
105	{
106	_bfd_error_handler
107	(_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) type (0x%x) datasz: 0x%x\n"),
108	abfd, note->type, type, datasz);
109	/* Clear all properties. */
110	elf_properties (abfd) = NULL;
111	return FALSE;
112	}
113
114	if (type >= GNU_PROPERTY_LOPROC)
115	{
116	if (type < GNU_PROPERTY_LOUSER && bed->parse_gnu_properties)
117	{
118	enum elf_property_kind kind
119	= bed->parse_gnu_properties (abfd, type, ptr, datasz);
120	if (kind == property_corrupt)
121	{
122	/* Clear all properties. */
123	elf_properties (abfd) = NULL;
124	return FALSE;
125	}
126	else if (kind != property_ignored)
127	goto next;
128	}
129	}
130	else
131	{
132	switch (type)
133	{
134	case GNU_PROPERTY_STACK_SIZE:
135	if (datasz != align_size)
136	{
137	_bfd_error_handler
138	(_("warning: %B: corrupt stack size: 0x%x\n"),
139	abfd, datasz);
140	/* Clear all properties. */
141	elf_properties (abfd) = NULL;
142	return FALSE;
143	}
144	prop = _bfd_elf_get_property (abfd, type, datasz);
145	if (datasz == 8)
146	prop->u.number = bfd_h_get_64 (abfd, ptr);
147	else
148	prop->u.number = bfd_h_get_32 (abfd, ptr);
149	prop->pr_kind = property_number;
150	goto next;
151
152	case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
153	if (datasz != 0)
154	{
155	_bfd_error_handler
156	(_("warning: %B: corrupt no copy on protected size: 0x%x\n"),
157	abfd, datasz);
158	/* Clear all properties. */
159	elf_properties (abfd) = NULL;
160	return FALSE;
161	}
162	prop = _bfd_elf_get_property (abfd, type, datasz);
163	prop->pr_kind = property_number;
164	goto next;
165
166	default:
167	break;
168	}
169	}
170
171	_bfd_error_handler
172	(_("warning: %B: unsupported GNU_PROPERTY_TYPE (%ld) type: 0x%x\n"),
173	abfd, note->type, type);
174
175	next:
176	ptr += (datasz + (align_size - 1)) & ~ (align_size - 1);
177	if (ptr == ptr_end)
178	break;
179
180	if (ptr > (ptr_end - 8))
181	goto bad_size;
182	}
183
184	return TRUE;
185	}
186
187	/* Merge GNU property BPROP with APROP. If APROP isn't NULL, return TRUE
188	if APROP is updated. Otherwise, return TRUE if BPROP should be merged
189	with ABFD. */
190
191	static bfd_boolean
192	elf_merge_gnu_properties (bfd abfd, elf_property aprop,
193	elf_property *bprop)
194	{
195	const struct elf_backend_data *bed = get_elf_backend_data (abfd);
196	unsigned int pr_type = aprop != NULL ? aprop->pr_type : bprop->pr_type;
197
198	if (bed->merge_gnu_properties != NULL
199	&& pr_type >= GNU_PROPERTY_LOPROC
200	&& pr_type < GNU_PROPERTY_LOUSER)
201	return bed->merge_gnu_properties (abfd, aprop, bprop);
202
203	switch (pr_type)
204	{
205	case GNU_PROPERTY_STACK_SIZE:
206	if (aprop != NULL && bprop != NULL)
207	{
208	if (bprop->u.number > aprop->u.number)
209	{
210	aprop->u.number = bprop->u.number;
211	return TRUE;
212	}
213	break;
214	}
215	/* FALLTHROUGH */
216
217	case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
218	/* Return TRUE if APROP is NULL to indicate that BPROP should
219	be added to ABFD. */
220	return aprop == NULL;
221
222	default:
223	/* Never should happen. */
224	abort ();
225	}
226
227	return FALSE;
228	}
229
230	/* Return the property of TYPE on LISTP and remove it from LISTP.
231	Return NULL if not found. */
232
233	static elf_property *
234	elf_find_and_remove_property (elf_property_list **listp,
235	unsigned int type)
236	{
237	elf_property_list *list;
238
239	for (list = *listp; list; list = list->next)
240	{
241	if (type == list->property.pr_type)
242	{
243	/* Remove this property. */
244	*listp = list->next;
245	return &list->property;
246	}
247	else if (type < list->property.pr_type)
248	break;
249	listp = &list->next;
250	}
251
252	return NULL;
253	}
254
255	/* Merge GNU property list LISTP with ABFD. /
256
257	static void
258	elf_merge_gnu_property_list (bfd abfd, elf_property_list *listp)
259	{
260	elf_property_list p, *lastp;
261	elf_property *pr;
262
263	/* Merge each GNU property in ABFD with the one on LISTP. /
264	lastp = &elf_properties (abfd);
265	for (p = *lastp; p; p = p->next)
266	{
267	pr = elf_find_and_remove_property (listp, p->property.pr_type);
268	/* Pass NULL to elf_merge_gnu_properties for the property which
269	isn't on LISTP. /
270	elf_merge_gnu_properties (abfd, &p->property, pr);
271	if (p->property.pr_kind == property_remove)
272	{
273	/* Remove this property. */
274	*lastp = p->next;
275	continue;
276	}
277	lastp = &p->next;
278	}
279
280	/* Merge the remaining properties on LISTP with ABFD. /
281	for (p = *listp; p != NULL; p = p->next)
282	if (elf_merge_gnu_properties (abfd, NULL, &p->property))
283	{
284	pr = _bfd_elf_get_property (abfd, p->property.pr_type,
285	p->property.pr_datasz);
286	/* It must be a new property. */
287	if (pr->pr_kind != property_unknown)
288	abort ();
289	/* Add a new property. */
290	*pr = p->property;
291	}
292	}
293
294	/* Set up GNU properties. */
295
296	void
297	_bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info)
298	{
299	bfd abfd, first_pbfd = NULL;
300	elf_property_list *list;
301	asection *sec;
302	bfd_boolean has_properties = FALSE;
303	const struct elf_backend_data *bed
304	= get_elf_backend_data (info->output_bfd);
305	unsigned int elfclass = bed->s->elfclass;
306	int elf_machine_code = bed->elf_machine_code;
307
308	/* Find the first relocatable ELF input with GNU properties. */
309	for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
310	if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
311	&& bfd_count_sections (abfd) != 0
312	&& elf_properties (abfd) != NULL)
313	{
314	has_properties = TRUE;
315
316	/* Ignore GNU properties from ELF objects with different machine
317	code or class. */
318	if ((elf_machine_code
319	== get_elf_backend_data (abfd)->elf_machine_code)
320	&& (elfclass
321	== get_elf_backend_data (abfd)->s->elfclass))
322	{
323	/* Keep .note.gnu.property section in FIRST_PBFD. */
324	first_pbfd = abfd;
325	break;
326	}
327	}
328
329	/* Do nothing if there is no .note.gnu.property section. */
330	if (!has_properties)
331	return;
332
333	/* Merge .note.gnu.property sections. */
334	for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
335	if (abfd != first_pbfd && bfd_count_sections (abfd) != 0)
336	{
337	elf_property_list *null_ptr = NULL;
338	elf_property_list **listp = &null_ptr;
339
340	/* Merge .note.gnu.property section in relocatable ELF input. */
341	if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
342	{
343	list = elf_properties (abfd);
344
345	/* Ignore GNU properties from ELF objects with different
346	machine code. */
347	if (list != NULL
348	&& (elf_machine_code
349	== get_elf_backend_data (abfd)->elf_machine_code))
350	listp = &elf_properties (abfd);
351	}
352	else
353	list = NULL;
354
355	/* Merge properties with FIRST_PBFD. FIRST_PBFD can be NULL
356	when all properties are from ELF objects with different
357	machine code or class. */
358	if (first_pbfd != NULL)
359	elf_merge_gnu_property_list (first_pbfd, listp);
360
361	if (list != NULL)
362	{
363	/* Discard .note.gnu.property section in the rest inputs. */
364	sec = bfd_get_section_by_name (abfd,
365	NOTE_GNU_PROPERTY_SECTION_NAME);
366	sec->output_section = bfd_abs_section_ptr;
367	}
368	}
369
370	/* Rewrite .note.gnu.property section so that GNU properties are
371	always sorted by type even if input GNU properties aren't sorted. */
372	if (first_pbfd != NULL)
373	{
374	unsigned int size;
375	unsigned int descsz;
376	bfd_byte *contents;
377	Elf_External_Note *e_note;
378	unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
379
380	sec = bfd_get_section_by_name (first_pbfd,
381	NOTE_GNU_PROPERTY_SECTION_NAME);
382
383	/* Update stack size in .note.gnu.property with -z stack-size=N
384	if N > 0. */
385	if (info->stacksize > 0)
386	{
387	elf_property *p;
388	bfd_vma stacksize = info->stacksize;
389
390	p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_STACK_SIZE,
391	align_size);
392	if (p->pr_kind == property_unknown)
393	{
394	/* Create GNU_PROPERTY_STACK_SIZE. */
395	p->u.number = stacksize;
396	p->pr_kind = property_number;
397	}
398	else if (stacksize > p->u.number)
399	p->u.number = stacksize;
400	}
401	else if (elf_properties (first_pbfd) == NULL)
402	{
403	/* Discard .note.gnu.property section if all properties have
404	been removed. */
405	sec->output_section = bfd_abs_section_ptr;
406	return;
407	}
408
409	/* Compute the section size. */
410	descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
411	descsz = (descsz + 3) & -(unsigned int) 4;
412	size = descsz;
413	for (list = elf_properties (first_pbfd);
414	list != NULL;
415	list = list->next)
416	{
417	/* There are 4 byte type + 4 byte datasz for each property. */
418	size += 4 + 4 + list->property.pr_datasz;
419	/* Align each property. */
420	size = (size + (align_size - 1)) & ~(align_size - 1);
421	}
422
423	/* Update .note.gnu.property section now. */
424	sec->size = size;
425	contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);
426
427	e_note = (Elf_External_Note *) contents;
428	bfd_h_put_32 (first_pbfd, sizeof "GNU", &e_note->namesz);
429	bfd_h_put_32 (first_pbfd, size - descsz, &e_note->descsz);
430	bfd_h_put_32 (first_pbfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
431	memcpy (e_note->name, "GNU", sizeof "GNU");
432
433	size = descsz;
434	for (list = elf_properties (first_pbfd);
435	list != NULL;
436	list = list->next)
437	{
438	/* There are 4 byte type + 4 byte datasz for each property. */
439	bfd_h_put_32 (first_pbfd, list->property.pr_type,
440	contents + size);
441	bfd_h_put_32 (first_pbfd, list->property.pr_datasz,
442	contents + size + 4);
443	size += 4 + 4;
444
445	/* Write out property value. */
446	switch (list->property.pr_kind)
447	{
448	case property_number:
449	switch (list->property.pr_datasz)
450	{
451	default:
452	/* Never should happen. */
453	abort ();
454
455	case 0:
456	break;
457
458	case 4:
459	bfd_h_put_32 (first_pbfd, list->property.u.number,
460	contents + size);
461	break;
462
463	case 8:
464	bfd_h_put_64 (first_pbfd, list->property.u.number,
465	contents + size);
466	break;
467	}
468	break;
469
470	default:
471	/* Never should happen. */
472	abort ();
473	}
474	size += list->property.pr_datasz;
475
476	/* Align each property. */
477	size = (size + (align_size - 1)) & ~ (align_size - 1);
478	}
479
480	/* Cache the section contents for elf_link_input_bfd. */
481	elf_section_data (sec)->this_hdr.contents = contents;
482	}
483	}