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gnu / binutils-gdb / c144f638337944101131d9fe6de4ab908f6d4c2d / . / bfd / elf-eh-frame.c
blob: 902d7c16334ea725b0caac8033d05422316bb4c5 [file] [log] [blame]
/* .eh_frame section optimization.
Copyright (C) 2001-2024 Free Software Foundation, Inc.
Written by Jakub Jelinek <jakub@redhat.com>.
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. */
#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "dwarf2.h"
#define EH_FRAME_HDR_SIZE 8
struct cie
{
unsigned int length;
unsigned int hash;
unsigned char version;
unsigned char local_personality;
char augmentation[20];
bfd_vma code_align;
bfd_signed_vma data_align;
bfd_vma ra_column;
bfd_vma augmentation_size;
union {
struct elf_link_hash_entry *h;
struct {
unsigned int bfd_id;
unsigned int index;
} sym;
unsigned int reloc_index;
} personality;
struct eh_cie_fde *cie_inf;
unsigned char per_encoding;
unsigned char lsda_encoding;
unsigned char fde_encoding;
unsigned char initial_insn_length;
unsigned char can_make_lsda_relative;
unsigned char initial_instructions[50];
};
/* If *ITER hasn't reached END yet, read the next byte into *RESULT and
move onto the next byte. Return true on success. */
static inline bool
read_byte (bfd_byte **iter, bfd_byte *end, unsigned char *result)
{
if (*iter >= end)
return false;
*result = *((*iter)++);
return true;
}
/* Move *ITER over LENGTH bytes, or up to END, whichever is closer.
Return true it was possible to move LENGTH bytes. */
static inline bool
skip_bytes (bfd_byte **iter, bfd_byte *end, bfd_size_type length)
{
if ((bfd_size_type) (end - *iter) < length)
{
*iter = end;
return false;
}
*iter += length;
return true;
}
/* Move *ITER over an leb128, stopping at END. Return true if the end
of the leb128 was found. */
static bool
skip_leb128 (bfd_byte **iter, bfd_byte *end)
{
unsigned char byte;
do
if (!read_byte (iter, end, &byte))
return false;
while (byte & 0x80);
return true;
}
/* Like skip_leb128, but treat the leb128 as an unsigned value and
store it in *VALUE. */
static bool
read_uleb128 (bfd_byte **iter, bfd_byte *end, bfd_vma *value)
{
bfd_byte *start, *p;
start = *iter;
if (!skip_leb128 (iter, end))
return false;
p = *iter;
*value = *--p;
while (p > start)
*value = (*value << 7) | (*--p & 0x7f);
return true;
}
/* Like read_uleb128, but for signed values. */
static bool
read_sleb128 (bfd_byte **iter, bfd_byte *end, bfd_signed_vma *value)
{
bfd_byte *start, *p;
start = *iter;
if (!skip_leb128 (iter, end))
return false;
p = *iter;
*value = ((*--p & 0x7f) ^ 0x40) - 0x40;
while (p > start)
*value = (*value << 7) | (*--p & 0x7f);
return true;
}
/* Return 0 if either encoding is variable width, or not yet known to bfd. */
static
int get_DW_EH_PE_width (int encoding, int ptr_size)
{
/* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame
was added to bfd. */
if ((encoding & 0x60) == 0x60)
return 0;
switch (encoding & 7)
{
case DW_EH_PE_udata2: return 2;
case DW_EH_PE_udata4: return 4;
case DW_EH_PE_udata8: return 8;
case DW_EH_PE_absptr: return ptr_size;
default:
break;
}
return 0;
}
#define get_DW_EH_PE_signed(encoding) (((encoding) & DW_EH_PE_signed) != 0)
/* Read a width sized value from memory. */
static bfd_vma
read_value (bfd *abfd, bfd_byte *buf, int width, int is_signed)
{
bfd_vma value;
switch (width)
{
case 2:
if (is_signed)
value = bfd_get_signed_16 (abfd, buf);
else
value = bfd_get_16 (abfd, buf);
break;
case 4:
if (is_signed)
value = bfd_get_signed_32 (abfd, buf);
else
value = bfd_get_32 (abfd, buf);
break;
case 8:
if (is_signed)
value = bfd_get_signed_64 (abfd, buf);
else
value = bfd_get_64 (abfd, buf);
break;
default:
BFD_FAIL ();
return 0;
}
return value;
}
/* Store a width sized value to memory. */
static void
write_value (bfd *abfd, bfd_byte *buf, bfd_vma value, int width)
{
switch (width)
{
case 2: bfd_put_16 (abfd, value, buf); break;
case 4: bfd_put_32 (abfd, value, buf); break;
case 8: bfd_put_64 (abfd, value, buf); break;
default: BFD_FAIL ();
}
}
/* Return one if C1 and C2 CIEs can be merged. */
static int
cie_eq (const void *e1, const void *e2)
{
const struct cie *c1 = (const struct cie *) e1;
const struct cie *c2 = (const struct cie *) e2;
if (c1->hash == c2->hash
&& c1->length == c2->length
&& c1->version == c2->version
&& c1->local_personality == c2->local_personality
&& strcmp (c1->augmentation, c2->augmentation) == 0
&& strcmp (c1->augmentation, "eh") != 0
&& c1->code_align == c2->code_align
&& c1->data_align == c2->data_align
&& c1->ra_column == c2->ra_column
&& c1->augmentation_size == c2->augmentation_size
&& memcmp (&c1->personality, &c2->personality,
sizeof (c1->personality)) == 0
&& (c1->cie_inf->u.cie.u.sec->output_section
== c2->cie_inf->u.cie.u.sec->output_section)
&& c1->per_encoding == c2->per_encoding
&& c1->lsda_encoding == c2->lsda_encoding
&& c1->fde_encoding == c2->fde_encoding
&& c1->initial_insn_length == c2->initial_insn_length
&& c1->initial_insn_length <= sizeof (c1->initial_instructions)
&& memcmp (c1->initial_instructions,
c2->initial_instructions,
c1->initial_insn_length) == 0)
return 1;
return 0;
}
static hashval_t
cie_hash (const void *e)
{
const struct cie *c = (const struct cie *) e;
return c->hash;
}
static hashval_t
cie_compute_hash (struct cie *c)
{
hashval_t h = 0;
size_t len;
h = iterative_hash_object (c->length, h);
h = iterative_hash_object (c->version, h);
h = iterative_hash (c->augmentation, strlen (c->augmentation) + 1, h);
h = iterative_hash_object (c->code_align, h);
h = iterative_hash_object (c->data_align, h);
h = iterative_hash_object (c->ra_column, h);
h = iterative_hash_object (c->augmentation_size, h);
h = iterative_hash_object (c->personality, h);
h = iterative_hash_object (c->cie_inf->u.cie.u.sec->output_section, h);
h = iterative_hash_object (c->per_encoding, h);
h = iterative_hash_object (c->lsda_encoding, h);
h = iterative_hash_object (c->fde_encoding, h);
h = iterative_hash_object (c->initial_insn_length, h);
len = c->initial_insn_length;
if (len > sizeof (c->initial_instructions))
len = sizeof (c->initial_instructions);
h = iterative_hash (c->initial_instructions, len, h);
c->hash = h;
return h;
}
/* Return the number of extra bytes that we'll be inserting into
ENTRY's augmentation string. */
static inline unsigned int
extra_augmentation_string_bytes (struct eh_cie_fde *entry)
{
unsigned int size = 0;
if (entry->cie)
{
if (entry->add_augmentation_size)
size++;
if (entry->u.cie.add_fde_encoding)
size++;
}
return size;
}
/* Likewise ENTRY's augmentation data. */
static inline unsigned int
extra_augmentation_data_bytes (struct eh_cie_fde *entry)
{
unsigned int size = 0;
if (entry->add_augmentation_size)
size++;
if (entry->cie && entry->u.cie.add_fde_encoding)
size++;
return size;
}
/* Return the size that ENTRY will have in the output. */
static unsigned int
size_of_output_cie_fde (struct eh_cie_fde *entry)
{
if (entry->removed)
return 0;
if (entry->size == 4)
return 4;
return (entry->size
+ extra_augmentation_string_bytes (entry)
+ extra_augmentation_data_bytes (entry));
}
/* Return the offset of the FDE or CIE after ENT. */
static unsigned int
next_cie_fde_offset (const struct eh_cie_fde *ent,
const struct eh_cie_fde *last,
const asection *sec)
{
while (++ent < last)
{
if (!ent->removed)
return ent->new_offset;
}
return sec->size;
}
/* Assume that the bytes between *ITER and END are CFA instructions.
Try to move *ITER past the first instruction and return true on
success. ENCODED_PTR_WIDTH gives the width of pointer entries. */
static bool
skip_cfa_op (bfd_byte **iter, bfd_byte *end, unsigned int encoded_ptr_width)
{
bfd_byte op;
bfd_vma length;
if (!read_byte (iter, end, &op))
return false;
switch (op & 0xc0 ? op & 0xc0 : op)
{
case DW_CFA_nop:
case DW_CFA_advance_loc:
case DW_CFA_restore:
case DW_CFA_remember_state:
case DW_CFA_restore_state:
case DW_CFA_GNU_window_save:
/* No arguments. */
return true;
case DW_CFA_offset:
case DW_CFA_restore_extended:
case DW_CFA_undefined:
case DW_CFA_same_value:
case DW_CFA_def_cfa_register:
case DW_CFA_def_cfa_offset:
case DW_CFA_def_cfa_offset_sf:
case DW_CFA_GNU_args_size:
/* One leb128 argument. */
return skip_leb128 (iter, end);
case DW_CFA_val_offset:
case DW_CFA_val_offset_sf:
case DW_CFA_offset_extended:
case DW_CFA_register:
case DW_CFA_def_cfa:
case DW_CFA_offset_extended_sf:
case DW_CFA_GNU_negative_offset_extended:
case DW_CFA_def_cfa_sf:
/* Two leb128 arguments. */
return (skip_leb128 (iter, end)
&& skip_leb128 (iter, end));
case DW_CFA_def_cfa_expression:
/* A variable-length argument. */
return (read_uleb128 (iter, end, &length)
&& skip_bytes (iter, end, length));
case DW_CFA_expression:
case DW_CFA_val_expression:
/* A leb128 followed by a variable-length argument. */
return (skip_leb128 (iter, end)
&& read_uleb128 (iter, end, &length)
&& skip_bytes (iter, end, length));
case DW_CFA_set_loc:
return skip_bytes (iter, end, encoded_ptr_width);
case DW_CFA_advance_loc1:
return skip_bytes (iter, end, 1);
case DW_CFA_advance_loc2:
return skip_bytes (iter, end, 2);
case DW_CFA_advance_loc4:
return skip_bytes (iter, end, 4);
case DW_CFA_MIPS_advance_loc8:
return skip_bytes (iter, end, 8);
default:
return false;
}
}
/* Try to interpret the bytes between BUF and END as CFA instructions.
If every byte makes sense, return a pointer to the first DW_CFA_nop
padding byte, or END if there is no padding. Return null otherwise.
ENCODED_PTR_WIDTH is as for skip_cfa_op. */
static bfd_byte *
skip_non_nops (bfd_byte *buf, bfd_byte *end, unsigned int encoded_ptr_width,
unsigned int *set_loc_count)
{
bfd_byte *last;
last = buf;
while (buf < end)
if (*buf == DW_CFA_nop)
buf++;
else
{
if (*buf == DW_CFA_set_loc)
++*set_loc_count;
if (!skip_cfa_op (&buf, end, encoded_ptr_width))
return 0;
last = buf;
}
return last;
}
/* Convert absolute encoding ENCODING into PC-relative form.
SIZE is the size of a pointer. */
static unsigned char
make_pc_relative (unsigned char encoding, unsigned int ptr_size)
{
if ((encoding & 0x7f) == DW_EH_PE_absptr)
switch (ptr_size)
{
case 2:
encoding |= DW_EH_PE_sdata2;
break;
case 4:
encoding |= DW_EH_PE_sdata4;
break;
case 8:
encoding |= DW_EH_PE_sdata8;
break;
}
return encoding | DW_EH_PE_pcrel;
}
/* Examine each .eh_frame_entry section and discard those
those that are marked SEC_EXCLUDE. */
static void
bfd_elf_discard_eh_frame_entry (struct eh_frame_hdr_info *hdr_info)
{
unsigned int i;
for (i = 0; i < hdr_info->array_count; i++)
{
if (hdr_info->u.compact.entries[i]->flags & SEC_EXCLUDE)
{
unsigned int j;
for (j = i + 1; j < hdr_info->array_count; j++)
hdr_info->u.compact.entries[j-1] = hdr_info->u.compact.entries[j];
hdr_info->array_count--;
hdr_info->u.compact.entries[hdr_info->array_count] = NULL;
i--;
}
}
}
/* Add a .eh_frame_entry section. */
static void
bfd_elf_record_eh_frame_entry (struct eh_frame_hdr_info *hdr_info,
asection *sec)
{
if (hdr_info->array_count == hdr_info->u.compact.allocated_entries)
{
if (hdr_info->u.compact.allocated_entries == 0)
{
hdr_info->frame_hdr_is_compact = true;
hdr_info->u.compact.allocated_entries = 2;
hdr_info->u.compact.entries =
bfd_malloc (hdr_info->u.compact.allocated_entries
* sizeof (hdr_info->u.compact.entries[0]));
}
else
{
hdr_info->u.compact.allocated_entries *= 2;
hdr_info->u.compact.entries =
bfd_realloc (hdr_info->u.compact.entries,
hdr_info->u.compact.allocated_entries
* sizeof (hdr_info->u.compact.entries[0]));
}
BFD_ASSERT (hdr_info->u.compact.entries);
}
hdr_info->u.compact.entries[hdr_info->array_count++] = sec;
}
/* Parse a .eh_frame_entry section. Figure out which text section it
references. */
bool
_bfd_elf_parse_eh_frame_entry (struct bfd_link_info *info,
asection *sec, struct elf_reloc_cookie *cookie)
{
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
unsigned long r_symndx;
asection *text_sec;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (sec->size == 0
|| sec->sec_info_type != SEC_INFO_TYPE_NONE)
{
return true;
}
if (sec->output_section && bfd_is_abs_section (sec->output_section))
{
/* At least one of the sections is being discarded from the
link, so we should just ignore them. */
return true;
}
if (cookie->rel == cookie->relend)
return false;
/* The first relocation is the function start. */
r_symndx = cookie->rel->r_info >> cookie->r_sym_shift;
if (r_symndx == STN_UNDEF)
return false;
text_sec = _bfd_elf_section_for_symbol (cookie, r_symndx, false);
if (text_sec == NULL)
return false;
elf_section_eh_frame_entry (text_sec) = sec;
if (text_sec->output_section
&& bfd_is_abs_section (text_sec->output_section))
sec->flags |= SEC_EXCLUDE;
sec->sec_info_type = SEC_INFO_TYPE_EH_FRAME_ENTRY;
elf_section_data (sec)->sec_info = text_sec;
bfd_elf_record_eh_frame_entry (hdr_info, sec);
return true;
}
/* Try to parse .eh_frame section SEC, which belongs to ABFD. Store the
information in the section's sec_info field on success. COOKIE
describes the relocations in SEC. */
void
_bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
asection *sec, struct elf_reloc_cookie *cookie)
{
#define REQUIRE(COND) \
do \
if (!(COND)) \
goto free_no_table; \
while (0)
bfd_byte *ehbuf = NULL, *buf, *end;
bfd_byte *last_fde;
struct eh_cie_fde *this_inf;
unsigned int hdr_length, hdr_id;
unsigned int cie_count;
struct cie *cie, *local_cies = NULL;
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
struct eh_frame_sec_info *sec_info = NULL;
unsigned int ptr_size;
unsigned int num_cies;
unsigned int num_entries;
elf_gc_mark_hook_fn gc_mark_hook;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (sec->size == 0
|| (sec->flags & SEC_HAS_CONTENTS) == 0
|| sec->sec_info_type != SEC_INFO_TYPE_NONE)
{
/* This file does not contain .eh_frame information. */
return;
}
if (bfd_is_abs_section (sec->output_section))
{
/* At least one of the sections is being discarded from the
link, so we should just ignore them. */
return;
}
/* Read the frame unwind information from abfd. */
REQUIRE (_bfd_elf_mmap_section_contents (abfd, sec, &ehbuf));
/* If .eh_frame section size doesn't fit into int, we cannot handle
it (it would need to use 64-bit .eh_frame format anyway). */
REQUIRE (sec->size == (unsigned int) sec->size);
ptr_size = (get_elf_backend_data (abfd)
->elf_backend_eh_frame_address_size (abfd, sec));
REQUIRE (ptr_size != 0);
/* Go through the section contents and work out how many FDEs and
CIEs there are. */
buf = ehbuf;
end = ehbuf + sec->size;
num_cies = 0;
num_entries = 0;
while (buf != end)
{
num_entries++;
/* Read the length of the entry. */
REQUIRE (skip_bytes (&buf, end, 4));
hdr_length = bfd_get_32 (abfd, buf - 4);
/* 64-bit .eh_frame is not supported. */
REQUIRE (hdr_length != 0xffffffff);
if (hdr_length == 0)
break;
REQUIRE (skip_bytes (&buf, end, 4));
hdr_id = bfd_get_32 (abfd, buf - 4);
if (hdr_id == 0)
num_cies++;
REQUIRE (skip_bytes (&buf, end, hdr_length - 4));
}
sec_info = (struct eh_frame_sec_info *)
bfd_zmalloc (sizeof (struct eh_frame_sec_info)
+ (num_entries - 1) * sizeof (struct eh_cie_fde));
REQUIRE (sec_info);
/* We need to have a "struct cie" for each CIE in this section. */
if (num_cies)
{
local_cies = (struct cie *) bfd_zmalloc (num_cies * sizeof (*local_cies));
REQUIRE (local_cies);
}
/* FIXME: octets_per_byte. */
#define ENSURE_NO_RELOCS(buf) \
while (cookie->rel < cookie->relend \
&& (cookie->rel->r_offset \
< (bfd_size_type) ((buf) - ehbuf))) \
{ \
REQUIRE (cookie->rel->r_info == 0); \
cookie->rel++; \
}
/* FIXME: octets_per_byte. */
#define SKIP_RELOCS(buf) \
while (cookie->rel < cookie->relend \
&& (cookie->rel->r_offset \
< (bfd_size_type) ((buf) - ehbuf))) \
cookie->rel++
/* FIXME: octets_per_byte. */
#define GET_RELOC(buf) \
((cookie->rel < cookie->relend \
&& (cookie->rel->r_offset \
== (bfd_size_type) ((buf) - ehbuf))) \
? cookie->rel : NULL)
buf = ehbuf;
cie_count = 0;
gc_mark_hook = get_elf_backend_data (abfd)->gc_mark_hook;
while ((bfd_size_type) (buf - ehbuf) != sec->size)
{
char *aug;
bfd_byte *start, *insns, *insns_end;
bfd_size_type length;
unsigned int set_loc_count;
this_inf = sec_info->entry + sec_info->count;
last_fde = buf;
/* Read the length of the entry. */
REQUIRE (skip_bytes (&buf, ehbuf + sec->size, 4));
hdr_length = bfd_get_32 (abfd, buf - 4);
/* The CIE/FDE must be fully contained in this input section. */
REQUIRE ((bfd_size_type) (buf - ehbuf) + hdr_length <= sec->size);
end = buf + hdr_length;
this_inf->offset = last_fde - ehbuf;
this_inf->size = 4 + hdr_length;
this_inf->reloc_index = cookie->rel - cookie->rels;
if (hdr_length == 0)
{
/* A zero-length CIE should only be found at the end of
the section, but allow multiple terminators. */
while (skip_bytes (&buf, ehbuf + sec->size, 4))
REQUIRE (bfd_get_32 (abfd, buf - 4) == 0);
REQUIRE ((bfd_size_type) (buf - ehbuf) == sec->size);
ENSURE_NO_RELOCS (buf);
sec_info->count++;
break;
}
REQUIRE (skip_bytes (&buf, end, 4));
hdr_id = bfd_get_32 (abfd, buf - 4);
if (hdr_id == 0)
{
unsigned int initial_insn_length;
/* CIE */
this_inf->cie = 1;
/* Point CIE to one of the section-local cie structures. */
cie = local_cies + cie_count++;
cie->cie_inf = this_inf;
cie->length = hdr_length;
start = buf;
REQUIRE (read_byte (&buf, end, &cie->version));
/* Cannot handle unknown versions. */
REQUIRE (cie->version == 1
|| cie->version == 3
|| cie->version == 4);
REQUIRE (strlen ((char *) buf) < sizeof (cie->augmentation));
strcpy (cie->augmentation, (char *) buf);
buf = (bfd_byte *) strchr ((char *) buf, '\0') + 1;
this_inf->u.cie.aug_str_len = buf - start - 1;
ENSURE_NO_RELOCS (buf);
if (buf[0] == 'e' && buf[1] == 'h')
{
/* GCC < 3.0 .eh_frame CIE */
/* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__
is private to each CIE, so we don't need it for anything.
Just skip it. */
REQUIRE (skip_bytes (&buf, end, ptr_size));
SKIP_RELOCS (buf);
}
if (cie->version >= 4)
{
REQUIRE (buf + 1 < end);
REQUIRE (buf[0] == ptr_size);
REQUIRE (buf[1] == 0);
buf += 2;
}
REQUIRE (read_uleb128 (&buf, end, &cie->code_align));
REQUIRE (read_sleb128 (&buf, end, &cie->data_align));
if (cie->version == 1)
{
REQUIRE (buf < end);
cie->ra_column = *buf++;
}
else
REQUIRE (read_uleb128 (&buf, end, &cie->ra_column));
ENSURE_NO_RELOCS (buf);
cie->lsda_encoding = DW_EH_PE_omit;
cie->fde_encoding = DW_EH_PE_omit;
cie->per_encoding = DW_EH_PE_omit;
aug = cie->augmentation;
if (aug[0] != 'e' || aug[1] != 'h')
{
if (*aug == 'z')
{
aug++;
REQUIRE (read_uleb128 (&buf, end, &cie->augmentation_size));
ENSURE_NO_RELOCS (buf);
}
while (*aug != '\0')
switch (*aug++)
{
case 'B':
break;
case 'L':
REQUIRE (read_byte (&buf, end, &cie->lsda_encoding));
ENSURE_NO_RELOCS (buf);
REQUIRE (get_DW_EH_PE_width (cie->lsda_encoding, ptr_size));
break;
case 'R':
REQUIRE (read_byte (&buf, end, &cie->fde_encoding));
ENSURE_NO_RELOCS (buf);
REQUIRE (get_DW_EH_PE_width (cie->fde_encoding, ptr_size));
break;
case 'S':
break;
case 'P':
{
int per_width;
REQUIRE (read_byte (&buf, end, &cie->per_encoding));
per_width = get_DW_EH_PE_width (cie->per_encoding,
ptr_size);
REQUIRE (per_width);
if ((cie->per_encoding & 0x70) == DW_EH_PE_aligned)
{
length = -(buf - ehbuf) & (per_width - 1);
REQUIRE (skip_bytes (&buf, end, length));
if (per_width == 8)
this_inf->u.cie.per_encoding_aligned8 = 1;
}
this_inf->u.cie.personality_offset = buf - start;
ENSURE_NO_RELOCS (buf);
/* Ensure we have a reloc here. */
REQUIRE (GET_RELOC (buf));
cie->personality.reloc_index
= cookie->rel - cookie->rels;
/* Cope with MIPS-style composite relocations. */
do
cookie->rel++;
while (GET_RELOC (buf) != NULL);
REQUIRE (skip_bytes (&buf, end, per_width));
}
break;
default:
/* Unrecognized augmentation. Better bail out. */
goto free_no_table;
}
}
this_inf->u.cie.aug_data_len
= buf - start - 1 - this_inf->u.cie.aug_str_len;
/* For shared libraries, try to get rid of as many RELATIVE relocs
as possible. */
if (bfd_link_pic (info)
&& (get_elf_backend_data (abfd)
->elf_backend_can_make_relative_eh_frame
(abfd, info, sec)))
{
if ((cie->fde_encoding & 0x70) == DW_EH_PE_absptr)
this_inf->make_relative = 1;
/* If the CIE doesn't already have an 'R' entry, it's fairly
easy to add one, provided that there's no aligned data
after the augmentation string. */
else if (cie->fde_encoding == DW_EH_PE_omit
&& (cie->per_encoding & 0x70) != DW_EH_PE_aligned)
{
if (*cie->augmentation == 0)
this_inf->add_augmentation_size = 1;
this_inf->u.cie.add_fde_encoding = 1;
this_inf->make_relative = 1;
}
if ((cie->lsda_encoding & 0x70) == DW_EH_PE_absptr)
cie->can_make_lsda_relative = 1;
}
/* If FDE encoding was not specified, it defaults to
DW_EH_absptr. */
if (cie->fde_encoding == DW_EH_PE_omit)
cie->fde_encoding = DW_EH_PE_absptr;
initial_insn_length = end - buf;
cie->initial_insn_length = initial_insn_length;
memcpy (cie->initial_instructions, buf,
initial_insn_length <= sizeof (cie->initial_instructions)
? initial_insn_length : sizeof (cie->initial_instructions));
insns = buf;
buf += initial_insn_length;
ENSURE_NO_RELOCS (buf);
if (!bfd_link_relocatable (info))
{
/* Keep info for merging cies. */
this_inf->u.cie.u.full_cie = cie;
this_inf->u.cie.per_encoding_relative
= (cie->per_encoding & 0x70) == DW_EH_PE_pcrel;
}
}
else
{
/* Find the corresponding CIE. */
unsigned int cie_offset = this_inf->offset + 4 - hdr_id;
for (cie = local_cies; cie < local_cies + cie_count; cie++)
if (cie_offset == cie->cie_inf->offset)
break;
/* Ensure this FDE references one of the CIEs in this input
section. */
REQUIRE (cie != local_cies + cie_count);
this_inf->u.fde.cie_inf = cie->cie_inf;
this_inf->make_relative = cie->cie_inf->make_relative;
this_inf->add_augmentation_size
= cie->cie_inf->add_augmentation_size;
ENSURE_NO_RELOCS (buf);
if ((sec->flags & SEC_LINKER_CREATED) == 0 || cookie->rels != NULL)
{
asection *rsec;
REQUIRE (GET_RELOC (buf));
/* Chain together the FDEs for each section. */
rsec = _bfd_elf_gc_mark_rsec (info, sec, gc_mark_hook,
cookie, NULL);
/* RSEC will be NULL if FDE was cleared out as it was belonging to
a discarded SHT_GROUP. */
if (rsec)
{
REQUIRE (rsec->owner == abfd);
this_inf->u.fde.next_for_section = elf_fde_list (rsec);
elf_fde_list (rsec) = this_inf;
}
}
/* Skip the initial location and address range. */
start = buf;
length = get_DW_EH_PE_width (cie->fde_encoding, ptr_size);
REQUIRE (skip_bytes (&buf, end, 2 * length));
SKIP_RELOCS (buf - length);
if (!GET_RELOC (buf - length)
&& read_value (abfd, buf - length, length, false) == 0)
{
(*info->callbacks->minfo)
/* xgettext:c-format */
(_("discarding zero address range FDE in %pB(%pA).\n"),
abfd, sec);
this_inf->u.fde.cie_inf = NULL;
}
/* Skip the augmentation size, if present. */
if (cie->augmentation[0] == 'z')
REQUIRE (read_uleb128 (&buf, end, &length));
else
length = 0;
/* Of the supported augmentation characters above, only 'L'
adds augmentation data to the FDE. This code would need to
be adjusted if any future augmentations do the same thing. */
if (cie->lsda_encoding != DW_EH_PE_omit)
{
SKIP_RELOCS (buf);
if (cie->can_make_lsda_relative && GET_RELOC (buf))
cie->cie_inf->u.cie.make_lsda_relative = 1;
this_inf->lsda_offset = buf - start;
/* If there's no 'z' augmentation, we don't know where the
CFA insns begin. Assume no padding. */
if (cie->augmentation[0] != 'z')
length = end - buf;
}
/* Skip over the augmentation data. */
REQUIRE (skip_bytes (&buf, end, length));
insns = buf;
buf = last_fde + 4 + hdr_length;
/* For NULL RSEC (cleared FDE belonging to a discarded section)
the relocations are commonly cleared. We do not sanity check if
all these relocations are cleared as (1) relocations to
.gcc_except_table will remain uncleared (they will get dropped
with the drop of this unused FDE) and (2) BFD already safely drops
relocations of any type to .eh_frame by
elf_section_ignore_discarded_relocs.
TODO: The .gcc_except_table entries should be also filtered as
.eh_frame entries; or GCC could rather use COMDAT for them. */
SKIP_RELOCS (buf);
}
/* Try to interpret the CFA instructions and find the first
padding nop. Shrink this_inf's size so that it doesn't
include the padding. */
length = get_DW_EH_PE_width (cie->fde_encoding, ptr_size);
set_loc_count = 0;
insns_end = skip_non_nops (insns, end, length, &set_loc_count);
/* If we don't understand the CFA instructions, we can't know
what needs to be adjusted there. */
if (insns_end == NULL
/* For the time being we don't support DW_CFA_set_loc in
CIE instructions. */
|| (set_loc_count && this_inf->cie))
goto free_no_table;
this_inf->size -= end - insns_end;
if (insns_end != end && this_inf->cie)
{
cie->initial_insn_length -= end - insns_end;
cie->length -= end - insns_end;
}
if (set_loc_count
&& ((cie->fde_encoding & 0x70) == DW_EH_PE_pcrel
|| this_inf->make_relative))
{
unsigned int cnt;
bfd_byte *p;
this_inf->set_loc = (unsigned int *)
bfd_malloc ((set_loc_count + 1) * sizeof (unsigned int));
REQUIRE (this_inf->set_loc);
this_inf->set_loc[0] = set_loc_count;
p = insns;
cnt = 0;
while (p < end)
{
if (*p == DW_CFA_set_loc)
this_inf->set_loc[++cnt] = p + 1 - start;
REQUIRE (skip_cfa_op (&p, end, length));
}
}
this_inf->removed = 1;
this_inf->fde_encoding = cie->fde_encoding;
this_inf->lsda_encoding = cie->lsda_encoding;
sec_info->count++;
}
BFD_ASSERT (sec_info->count == num_entries);
BFD_ASSERT (cie_count == num_cies);
elf_section_data (sec)->sec_info = sec_info;
sec->sec_info_type = SEC_INFO_TYPE_EH_FRAME;
if (!bfd_link_relocatable (info))
{
/* Keep info for merging cies. */
sec_info->cies = local_cies;
local_cies = NULL;
}
goto success;
free_no_table:
_bfd_error_handler
/* xgettext:c-format */
(_("error in %pB(%pA); no .eh_frame_hdr table will be created"),
abfd, sec);
hdr_info->u.dwarf.table = false;
free (sec_info);
success:
_bfd_elf_munmap_section_contents (sec, ehbuf);
free (local_cies);
#undef REQUIRE
}
/* Order eh_frame_hdr entries by the VMA of their text section. */
static int
cmp_eh_frame_hdr (const void *a, const void *b)
{
bfd_vma text_a;
bfd_vma text_b;
asection *sec;
sec = *(asection *const *)a;
sec = (asection *) elf_section_data (sec)->sec_info;
text_a = sec->output_section->vma + sec->output_offset;
sec = *(asection *const *)b;
sec = (asection *) elf_section_data (sec)->sec_info;
text_b = sec->output_section->vma + sec->output_offset;
if (text_a < text_b)
return -1;
return text_a > text_b;
}
/* Add space for a CANTUNWIND terminator to SEC if the text sections
referenced by it and NEXT are not contiguous, or NEXT is NULL. */
static void
add_eh_frame_hdr_terminator (asection *sec,
asection *next)
{
bfd_vma end;
bfd_vma next_start;
asection *text_sec;
if (next)
{
/* See if there is a gap (presumably a text section without unwind info)
between these two entries. */
text_sec = (asection *) elf_section_data (sec)->sec_info;
end = text_sec->output_section->vma + text_sec->output_offset
+ text_sec->size;
text_sec = (asection *) elf_section_data (next)->sec_info;
next_start = text_sec->output_section->vma + text_sec->output_offset;
if (end == next_start)
return;
}
/* Add space for a CANTUNWIND terminator. */
if (!sec->rawsize)
sec->rawsize = sec->size;
bfd_set_section_size (sec, sec->size + 8);
}
/* Finish a pass over all .eh_frame_entry sections. */
bool
_bfd_elf_end_eh_frame_parsing (struct bfd_link_info *info)
{
struct eh_frame_hdr_info *hdr_info;
unsigned int i;
hdr_info = &elf_hash_table (info)->eh_info;
if (info->eh_frame_hdr_type != COMPACT_EH_HDR
|| hdr_info->array_count == 0)
return false;
bfd_elf_discard_eh_frame_entry (hdr_info);
qsort (hdr_info->u.compact.entries, hdr_info->array_count,
sizeof (asection *), cmp_eh_frame_hdr);
for (i = 0; i < hdr_info->array_count - 1; i++)
{
add_eh_frame_hdr_terminator (hdr_info->u.compact.entries[i],
hdr_info->u.compact.entries[i + 1]);
}
/* Add a CANTUNWIND terminator after the last entry. */
add_eh_frame_hdr_terminator (hdr_info->u.compact.entries[i], NULL);
return true;
}
/* Mark all relocations against CIE or FDE ENT, which occurs in
.eh_frame section SEC. COOKIE describes the relocations in SEC;
its "rel" field can be changed freely. */
static bool
mark_entry (struct bfd_link_info *info, asection *sec,
struct eh_cie_fde *ent, elf_gc_mark_hook_fn gc_mark_hook,
struct elf_reloc_cookie *cookie)
{
/* FIXME: octets_per_byte. */
for (cookie->rel = cookie->rels + ent->reloc_index;
cookie->rel < cookie->relend
&& cookie->rel->r_offset < ent->offset + ent->size;
cookie->rel++)
if (!_bfd_elf_gc_mark_reloc (info, sec, gc_mark_hook, cookie))
return false;
return true;
}
/* Mark all the relocations against FDEs that relate to code in input
section SEC. The FDEs belong to .eh_frame section EH_FRAME, whose
relocations are described by COOKIE. */
bool
_bfd_elf_gc_mark_fdes (struct bfd_link_info *info, asection *sec,
asection *eh_frame, elf_gc_mark_hook_fn gc_mark_hook,
struct elf_reloc_cookie *cookie)
{
struct eh_cie_fde *fde, *cie;
for (fde = elf_fde_list (sec); fde; fde = fde->u.fde.next_for_section)
{
if (!mark_entry (info, eh_frame, fde, gc_mark_hook, cookie))
return false;
/* At this stage, all cie_inf fields point to local CIEs, so we
can use the same cookie to refer to them. */
cie = fde->u.fde.cie_inf;
if (cie != NULL && !cie->u.cie.gc_mark)
{
cie->u.cie.gc_mark = 1;
if (!mark_entry (info, eh_frame, cie, gc_mark_hook, cookie))
return false;
}
}
return true;
}
/* Input section SEC of ABFD is an .eh_frame section that contains the
CIE described by CIE_INF. Return a version of CIE_INF that is going
to be kept in the output, adding CIE_INF to the output if necessary.
HDR_INFO is the .eh_frame_hdr information and COOKIE describes the
relocations in REL. */
static struct eh_cie_fde *
find_merged_cie (bfd *abfd, struct bfd_link_info *info, asection *sec,
struct eh_frame_hdr_info *hdr_info,
struct elf_reloc_cookie *cookie,
struct eh_cie_fde *cie_inf)
{
unsigned long r_symndx;
struct cie *cie, *new_cie;
Elf_Internal_Rela *rel;
void **loc;
/* Use CIE_INF if we have already decided to keep it. */
if (!cie_inf->removed)
return cie_inf;
/* If we have merged CIE_INF with another CIE, use that CIE instead. */
if (cie_inf->u.cie.merged)
return cie_inf->u.cie.u.merged_with;
cie = cie_inf->u.cie.u.full_cie;
/* Assume we will need to keep CIE_INF. */
cie_inf->removed = 0;
cie_inf->u.cie.u.sec = sec;
/* If we are not merging CIEs, use CIE_INF. */
if (cie == NULL)
return cie_inf;
if (cie->per_encoding != DW_EH_PE_omit)
{
bool per_binds_local;
/* Work out the address of personality routine, or at least
enough info that we could calculate the address had we made a
final section layout. The symbol on the reloc is enough,
either the hash for a global, or (bfd id, index) pair for a
local. The assumption here is that no one uses addends on
the reloc. */
rel = cookie->rels + cie->personality.reloc_index;
memset (&cie->personality, 0, sizeof (cie->personality));
#ifdef BFD64
if (elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64)
r_symndx = ELF64_R_SYM (rel->r_info);
else
#endif
r_symndx = ELF32_R_SYM (rel->r_info);
if (r_symndx >= cookie->locsymcount
|| ELF_ST_BIND (cookie->locsyms[r_symndx].st_info) != STB_LOCAL)
{
struct elf_link_hash_entry *h;
r_symndx -= cookie->extsymoff;
h = cookie->sym_hashes[r_symndx];
while (h->root.type == bfd_link_hash_indirect
|| h->root.type == bfd_link_hash_warning)
h = (struct elf_link_hash_entry *) h->root.u.i.link;
cie->personality.h = h;
per_binds_local = SYMBOL_REFERENCES_LOCAL (info, h);
}
else
{
Elf_Internal_Sym *sym;
asection *sym_sec;
sym = &cookie->locsyms[r_symndx];
sym_sec = bfd_section_from_elf_index (abfd, sym->st_shndx);
if (sym_sec == NULL)
return cie_inf;
if (sym_sec->kept_section != NULL)
sym_sec = sym_sec->kept_section;
if (sym_sec->output_section == NULL)
return cie_inf;
cie->local_personality = 1;
cie->personality.sym.bfd_id = abfd->id;
cie->personality.sym.index = r_symndx;
per_binds_local = true;
}
if (per_binds_local
&& bfd_link_pic (info)
&& (cie->per_encoding & 0x70) == DW_EH_PE_absptr
&& (get_elf_backend_data (abfd)
->elf_backend_can_make_relative_eh_frame (abfd, info, sec)))
{
cie_inf->u.cie.make_per_encoding_relative = 1;
cie_inf->u.cie.per_encoding_relative = 1;
}
}
/* See if we can merge this CIE with an earlier one. */
cie_compute_hash (cie);
if (hdr_info->u.dwarf.cies == NULL)
{
hdr_info->u.dwarf.cies = htab_try_create (1, cie_hash, cie_eq, free);
if (hdr_info->u.dwarf.cies == NULL)
return cie_inf;
}
loc = htab_find_slot_with_hash (hdr_info->u.dwarf.cies, cie,
cie->hash, INSERT);
if (loc == NULL)
return cie_inf;
new_cie = (struct cie *) *loc;
if (new_cie == NULL)
{
/* Keep CIE_INF and record it in the hash table. */
new_cie = (struct cie *) malloc (sizeof (struct cie));
if (new_cie == NULL)
return cie_inf;
memcpy (new_cie, cie, sizeof (struct cie));
*loc = new_cie;
}
else
{
/* Merge CIE_INF with NEW_CIE->CIE_INF. */
cie_inf->removed = 1;
cie_inf->u.cie.merged = 1;
cie_inf->u.cie.u.merged_with = new_cie->cie_inf;
if (cie_inf->u.cie.make_lsda_relative)
new_cie->cie_inf->u.cie.make_lsda_relative = 1;
}
return new_cie->cie_inf;
}
/* For a given OFFSET in SEC, return the delta to the new location
after .eh_frame editing. */
static bfd_signed_vma
offset_adjust (bfd_vma offset, const asection *sec)
{
struct eh_frame_sec_info *sec_info
= (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
unsigned int lo, hi, mid;
struct eh_cie_fde *ent = NULL;
bfd_signed_vma delta;
lo = 0;
hi = sec_info->count;
if (hi == 0)
return 0;
while (lo < hi)
{
mid = (lo + hi) / 2;
ent = &sec_info->entry[mid];
if (offset < ent->offset)
hi = mid;
else if (mid + 1 >= hi)
break;
else if (offset >= ent[1].offset)
lo = mid + 1;
else
break;
}
if (!ent->removed)
delta = (bfd_vma) ent->new_offset - (bfd_vma) ent->offset;
else if (ent->cie && ent->u.cie.merged)
{
struct eh_cie_fde *cie = ent->u.cie.u.merged_with;
delta = ((bfd_vma) cie->new_offset + cie->u.cie.u.sec->output_offset
- (bfd_vma) ent->offset - sec->output_offset);
}
else
{
/* Is putting the symbol on the next entry best for a deleted
CIE/FDE? */
struct eh_cie_fde *last = sec_info->entry + sec_info->count;
delta = ((bfd_vma) next_cie_fde_offset (ent, last, sec)
- (bfd_vma) ent->offset);
return delta;
}
/* Account for editing within this CIE/FDE. */
offset -= ent->offset;
if (ent->cie)
{
unsigned int extra
= ent->add_augmentation_size + ent->u.cie.add_fde_encoding;
if (extra == 0
|| offset <= 9u + ent->u.cie.aug_str_len)
return delta;
delta += extra;
if (offset <= 9u + ent->u.cie.aug_str_len + ent->u.cie.aug_data_len)
return delta;
delta += extra;
}
else
{
unsigned int ptr_size, width, extra = ent->add_augmentation_size;
if (offset <= 12 || extra == 0)
return delta;
ptr_size = (get_elf_backend_data (sec->owner)
->elf_backend_eh_frame_address_size (sec->owner, sec));
width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
if (offset <= 8 + 2 * width)
return delta;
delta += extra;
}
return delta;
}
/* Adjust a global symbol defined in .eh_frame, so that it stays
relative to its original CIE/FDE. It is assumed that a symbol
defined at the beginning of a CIE/FDE belongs to that CIE/FDE
rather than marking the end of the previous CIE/FDE. This matters
when a CIE is merged with a previous CIE, since the symbol is
moved to the merged CIE. */
bool
_bfd_elf_adjust_eh_frame_global_symbol (struct elf_link_hash_entry *h,
void *arg ATTRIBUTE_UNUSED)
{
asection *sym_sec;
bfd_signed_vma delta;
if (h->root.type != bfd_link_hash_defined
&& h->root.type != bfd_link_hash_defweak)
return true;
sym_sec = h->root.u.def.section;
if (sym_sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME
|| elf_section_data (sym_sec)->sec_info == NULL)
return true;
delta = offset_adjust (h->root.u.def.value, sym_sec);
h->root.u.def.value += delta;
return true;
}
/* The same for all local symbols defined in .eh_frame. Returns true
if any symbol was changed. */
static int
adjust_eh_frame_local_symbols (const asection *sec,
struct elf_reloc_cookie *cookie)
{
int adjusted = 0;
if (cookie->locsymcount > 1)
{
unsigned int shndx = elf_section_data (sec)->this_idx;
Elf_Internal_Sym *end_sym = cookie->locsyms + cookie->locsymcount;
Elf_Internal_Sym *sym;
for (sym = cookie->locsyms + 1; sym < end_sym; ++sym)
if (sym->st_info <= ELF_ST_INFO (STB_LOCAL, STT_OBJECT)
&& sym->st_shndx == shndx)
{
bfd_signed_vma delta = offset_adjust (sym->st_value, sec);
if (delta != 0)
{
adjusted = 1;
sym->st_value += delta;
}
}
}
return adjusted;
}
/* This function is called for each input file before the .eh_frame
section is relocated. It discards duplicate CIEs and FDEs for discarded
functions. The function returns TRUE iff any entries have been
deleted. */
bool
_bfd_elf_discard_section_eh_frame
(bfd *abfd, struct bfd_link_info *info, asection *sec,
bool (*reloc_symbol_deleted_p) (bfd_vma, void *),
struct elf_reloc_cookie *cookie)
{
struct eh_cie_fde *ent;
struct eh_frame_sec_info *sec_info;
struct eh_frame_hdr_info *hdr_info;
unsigned int ptr_size, offset, eh_alignment;
int changed;
if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
return false;
sec_info = (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
if (sec_info == NULL)
return false;
ptr_size = (get_elf_backend_data (sec->owner)
->elf_backend_eh_frame_address_size (sec->owner, sec));
hdr_info = &elf_hash_table (info)->eh_info;
for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
if (ent->size == 4)
/* There should only be one zero terminator, on the last input
file supplying .eh_frame (crtend.o). Remove any others. */
ent->removed = sec->map_head.s != NULL;
else if (!ent->cie && ent->u.fde.cie_inf != NULL)
{
bool keep;
if ((sec->flags & SEC_LINKER_CREATED) != 0 && cookie->rels == NULL)
{
unsigned int width
= get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
bfd_vma value
= read_value (abfd, sec->contents + ent->offset + 8 + width,
width, get_DW_EH_PE_signed (ent->fde_encoding));
keep = value != 0;
}
else
{
cookie->rel = cookie->rels + ent->reloc_index;
/* FIXME: octets_per_byte. */
BFD_ASSERT (cookie->rel < cookie->relend
&& cookie->rel->r_offset == ent->offset + 8);
keep = !(*reloc_symbol_deleted_p) (ent->offset + 8, cookie);
}
if (keep)
{
if (bfd_link_pic (info)
&& (((ent->fde_encoding & 0x70) == DW_EH_PE_absptr
&& ent->make_relative == 0)
|| (ent->fde_encoding & 0x70) == DW_EH_PE_aligned))
{
static int num_warnings_issued = 0;
/* If a shared library uses absolute pointers
which we cannot turn into PC relative,
don't create the binary search table,
since it is affected by runtime relocations. */
hdr_info->u.dwarf.table = false;
/* Only warn if --eh-frame-hdr was specified. */
if (info->eh_frame_hdr_type != 0)
{
if (num_warnings_issued < 10)
{
_bfd_error_handler
/* xgettext:c-format */
(_("FDE encoding in %pB(%pA) prevents .eh_frame_hdr"
" table being created"), abfd, sec);
num_warnings_issued ++;
}
else if (num_warnings_issued == 10)
{
_bfd_error_handler
(_("further warnings about FDE encoding preventing .eh_frame_hdr generation dropped"));
num_warnings_issued ++;
}
}
}
ent->removed = 0;
hdr_info->u.dwarf.fde_count++;
ent->u.fde.cie_inf = find_merged_cie (abfd, info, sec, hdr_info,
cookie, ent->u.fde.cie_inf);
}
}
free (sec_info->cies);
sec_info->cies = NULL;
/* It may be that some .eh_frame input section has greater alignment
than other .eh_frame sections. In that case we run the risk of
padding with zeros before that section, which would be seen as a
zero terminator. Alignment padding must be added *inside* the
last FDE instead. For other FDEs we align according to their
encoding, in order to align FDE address range entries naturally. */
offset = 0;
changed = 0;
for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
if (!ent->removed)
{
eh_alignment = 4;
if (ent->size == 4)
;
else if (ent->cie)
{
if (ent->u.cie.per_encoding_aligned8)
eh_alignment = 8;
}
else
{
eh_alignment = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
if (eh_alignment < 4)
eh_alignment = 4;
}
offset = (offset + eh_alignment - 1) & -eh_alignment;
ent->new_offset = offset;
if (ent->new_offset != ent->offset)
changed = 1;
offset += size_of_output_cie_fde (ent);
}
eh_alignment = 4;
offset = (offset + eh_alignment - 1) & -eh_alignment;
sec->rawsize = sec->size;
sec->size = offset;
if (sec->size != sec->rawsize)
changed = 1;
if (changed && adjust_eh_frame_local_symbols (sec, cookie))
{
Elf_Internal_Shdr *symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
symtab_hdr->contents = (unsigned char *) cookie->locsyms;
}
return changed;
}
/* This function is called for .eh_frame_hdr section after
_bfd_elf_discard_section_eh_frame has been called on all .eh_frame
input sections. It finalizes the size of .eh_frame_hdr section. */
bool
_bfd_elf_discard_section_eh_frame_hdr (struct bfd_link_info *info)
{
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
asection *sec;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (!hdr_info->frame_hdr_is_compact && hdr_info->u.dwarf.cies != NULL)
{
htab_delete (hdr_info->u.dwarf.cies);
hdr_info->u.dwarf.cies = NULL;
}
sec = hdr_info->hdr_sec;
if (sec == NULL)
return false;
if (info->eh_frame_hdr_type == COMPACT_EH_HDR)
{
/* For compact frames we only add the header. The actual table comes
from the .eh_frame_entry sections. */
sec->size = 8;
}
else
{
sec->size = EH_FRAME_HDR_SIZE;
if (hdr_info->u.dwarf.table)
sec->size += 4 + hdr_info->u.dwarf.fde_count * 8;
}
return true;
}
/* Return true if there is at least one non-empty .eh_frame section in
input files. Can only be called after ld has mapped input to
output sections, and before sections are stripped. */
bool
_bfd_elf_eh_frame_present (struct bfd_link_info *info)
{
asection *eh = bfd_get_section_by_name (info->output_bfd, ".eh_frame");
if (eh == NULL)
return false;
/* Count only sections which have at least a single CIE or FDE.
There cannot be any CIE or FDE <= 8 bytes. */
for (eh = eh->map_head.s; eh != NULL; eh = eh->map_head.s)
if (eh->size > 8)
return true;
return false;
}
/* Return true if there is at least one .eh_frame_entry section in
input files. */
bool
_bfd_elf_eh_frame_entry_present (struct bfd_link_info *info)
{
asection *o;
bfd *abfd;
for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
{
for (o = abfd->sections; o; o = o->next)
{
const char *name = bfd_section_name (o);
if (strcmp (name, ".eh_frame_entry")
&& !bfd_is_abs_section (o->output_section))
return true;
}
}
return false;
}
/* This function is called from size_dynamic_sections.
It needs to decide whether .eh_frame_hdr should be output or not,
because when the dynamic symbol table has been sized it is too late
to strip sections. */
bool
_bfd_elf_maybe_strip_eh_frame_hdr (struct bfd_link_info *info)
{
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
struct bfd_link_hash_entry *bh = NULL;
struct elf_link_hash_entry *h;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (hdr_info->hdr_sec == NULL)
return true;
if (bfd_is_abs_section (hdr_info->hdr_sec->output_section)
|| info->eh_frame_hdr_type == 0
|| (info->eh_frame_hdr_type == DWARF2_EH_HDR
&& !_bfd_elf_eh_frame_present (info))
|| (info->eh_frame_hdr_type == COMPACT_EH_HDR
&& !_bfd_elf_eh_frame_entry_present (info)))
{
hdr_info->hdr_sec->flags |= SEC_EXCLUDE;
hdr_info->hdr_sec = NULL;
return true;
}
/* Add a hidden symbol so that systems without access to PHDRs can
find the table. */
if (! (_bfd_generic_link_add_one_symbol
(info, info->output_bfd, "__GNU_EH_FRAME_HDR", BSF_LOCAL,
hdr_info->hdr_sec, 0, NULL, false, false, &bh)))
return false;
h = (struct elf_link_hash_entry *) bh;
h->def_regular = 1;
h->other = STV_HIDDEN;
get_elf_backend_data
(info->output_bfd)->elf_backend_hide_symbol (info, h, true);
if (!hdr_info->frame_hdr_is_compact)
hdr_info->u.dwarf.table = true;
return true;
}
/* Adjust an address in the .eh_frame section. Given OFFSET within
SEC, this returns the new offset in the adjusted .eh_frame section,
or -1 if the address refers to a CIE/FDE which has been removed
or to offset with dynamic relocation which is no longer needed. */
bfd_vma
_bfd_elf_eh_frame_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED,
struct bfd_link_info *info ATTRIBUTE_UNUSED,
asection *sec,
bfd_vma offset)
{
struct eh_frame_sec_info *sec_info;
unsigned int lo, hi, mid;
if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
return offset;
sec_info = (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
if (offset >= sec->rawsize)
return offset - sec->rawsize + sec->size;
lo = 0;
hi = sec_info->count;
mid = 0;
while (lo < hi)
{
mid = (lo + hi) / 2;
if (offset < sec_info->entry[mid].offset)
hi = mid;
else if (offset
>= sec_info->entry[mid].offset + sec_info->entry[mid].size)
lo = mid + 1;
else
break;
}
BFD_ASSERT (lo < hi);
/* FDE or CIE was removed. */
if (sec_info->entry[mid].removed)
return (bfd_vma) -1;
/* If converting personality pointers to DW_EH_PE_pcrel, there will be
no need for run-time relocation against the personality field. */
if (sec_info->entry[mid].cie
&& sec_info->entry[mid].u.cie.make_per_encoding_relative
&& offset == (sec_info->entry[mid].offset + 8
+ sec_info->entry[mid].u.cie.personality_offset))
return (bfd_vma) -2;
/* If converting to DW_EH_PE_pcrel, there will be no need for run-time
relocation against FDE's initial_location field. */
if (!sec_info->entry[mid].cie
&& sec_info->entry[mid].make_relative
&& offset == sec_info->entry[mid].offset + 8)
return (bfd_vma) -2;
/* If converting LSDA pointers to DW_EH_PE_pcrel, there will be no need
for run-time relocation against LSDA field. */
if (!sec_info->entry[mid].cie
&& sec_info->entry[mid].u.fde.cie_inf->u.cie.make_lsda_relative
&& offset == (sec_info->entry[mid].offset + 8
+ sec_info->entry[mid].lsda_offset))
return (bfd_vma) -2;
/* If converting to DW_EH_PE_pcrel, there will be no need for run-time
relocation against DW_CFA_set_loc's arguments. */
if (sec_info->entry[mid].set_loc
&& sec_info->entry[mid].make_relative
&& (offset >= sec_info->entry[mid].offset + 8
+ sec_info->entry[mid].set_loc[1]))
{
unsigned int cnt;
for (cnt = 1; cnt <= sec_info->entry[mid].set_loc[0]; cnt++)
if (offset == sec_info->entry[mid].offset + 8
+ sec_info->entry[mid].set_loc[cnt])
return (bfd_vma) -2;
}
/* Any new augmentation bytes go before the first relocation. */
return (offset + sec_info->entry[mid].new_offset
- sec_info->entry[mid].offset
+ extra_augmentation_string_bytes (sec_info->entry + mid)
+ extra_augmentation_data_bytes (sec_info->entry + mid));
}
/* Write out .eh_frame_entry section. Add CANTUNWIND terminator if needed.
Also check that the contents look sane. */
bool
_bfd_elf_write_section_eh_frame_entry (bfd *abfd, struct bfd_link_info *info,
asection *sec, bfd_byte *contents)
{
const struct elf_backend_data *bed;
bfd_byte cantunwind[8];
bfd_vma addr;
bfd_vma last_addr;
bfd_vma offset;
asection *text_sec = (asection *) elf_section_data (sec)->sec_info;
if (!sec->rawsize)
sec->rawsize = sec->size;
BFD_ASSERT (sec->sec_info_type == SEC_INFO_TYPE_EH_FRAME_ENTRY);
/* Check to make sure that the text section corresponding to this eh_frame_entry
section has not been excluded. In particular, mips16 stub entries will be
excluded outside of the normal process. */
if (sec->flags & SEC_EXCLUDE
|| text_sec->flags & SEC_EXCLUDE)
return true;
if (!bfd_set_section_contents (abfd, sec->output_section, contents,
sec->output_offset, sec->rawsize))
return false;
last_addr = bfd_get_signed_32 (abfd, contents);
/* Check that all the entries are in order. */
for (offset = 8; offset < sec->rawsize; offset += 8)
{
addr = bfd_get_signed_32 (abfd, contents + offset) + offset;
if (addr <= last_addr)
{
/* xgettext:c-format */
_bfd_error_handler (_("%pB: %pA not in order"), sec->owner, sec);
return false;
}
last_addr = addr;
}
addr = text_sec->output_section->vma + text_sec->output_offset
+ text_sec->size;
addr &= ~1;
addr -= (sec->output_section->vma + sec->output_offset + sec->rawsize);
if (addr & 1)
{
/* xgettext:c-format */
_bfd_error_handler (_("%pB: %pA invalid input section size"),
sec->owner, sec);
bfd_set_error (bfd_error_bad_value);
return false;
}
if (last_addr >= addr + sec->rawsize)
{
/* xgettext:c-format */
_bfd_error_handler (_("%pB: %pA points past end of text section"),
sec->owner, sec);
bfd_set_error (bfd_error_bad_value);
return false;
}
if (sec->size == sec->rawsize)
return true;
bed = get_elf_backend_data (abfd);
BFD_ASSERT (sec->size == sec->rawsize + 8);
BFD_ASSERT ((addr & 1) == 0);
BFD_ASSERT (bed->cant_unwind_opcode);
bfd_put_32 (abfd, addr, cantunwind);
bfd_put_32 (abfd, (*bed->cant_unwind_opcode) (info), cantunwind + 4);
return bfd_set_section_contents (abfd, sec->output_section, cantunwind,
sec->output_offset + sec->rawsize, 8);
}
/* Write out .eh_frame section. This is called with the relocated
contents. */
bool
_bfd_elf_write_section_eh_frame (bfd *abfd,
struct bfd_link_info *info,
asection *sec,
bfd_byte *contents)
{
struct eh_frame_sec_info *sec_info;
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
unsigned int ptr_size;
struct eh_cie_fde *ent, *last_ent;
if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
/* FIXME: octets_per_byte. */
return bfd_set_section_contents (abfd, sec->output_section, contents,
sec->output_offset, sec->size);
ptr_size = (get_elf_backend_data (abfd)
->elf_backend_eh_frame_address_size (abfd, sec));
BFD_ASSERT (ptr_size != 0);
sec_info = (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (hdr_info->u.dwarf.table && hdr_info->u.dwarf.array == NULL)
{
hdr_info->frame_hdr_is_compact = false;
hdr_info->u.dwarf.array = (struct eh_frame_array_ent *)
bfd_malloc (hdr_info->u.dwarf.fde_count
* sizeof (*hdr_info->u.dwarf.array));
}
if (hdr_info->u.dwarf.array == NULL)
hdr_info = NULL;
/* The new offsets can be bigger or smaller than the original offsets.
We therefore need to make two passes over the section: one backward
pass to move entries up and one forward pass to move entries down.
The two passes won't interfere with each other because entries are
not reordered */
for (ent = sec_info->entry + sec_info->count; ent-- != sec_info->entry;)
if (!ent->removed && ent->new_offset > ent->offset)
memmove (contents + ent->new_offset, contents + ent->offset, ent->size);
for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
if (!ent->removed && ent->new_offset < ent->offset)
memmove (contents + ent->new_offset, contents + ent->offset, ent->size);
last_ent = sec_info->entry + sec_info->count;
for (ent = sec_info->entry; ent < last_ent; ++ent)
{
unsigned char *buf, *end;
unsigned int new_size;
if (ent->removed)
continue;
if (ent->size == 4)
{
/* Any terminating FDE must be at the end of the section. */
BFD_ASSERT (ent == last_ent - 1);
continue;
}
buf = contents + ent->new_offset;
end = buf + ent->size;
new_size = next_cie_fde_offset (ent, last_ent, sec) - ent->new_offset;
/* Update the size. It may be shrinked. */
bfd_put_32 (abfd, new_size - 4, buf);
/* Filling the extra bytes with DW_CFA_nops. */
if (new_size != ent->size)
memset (end, 0, new_size - ent->size);
if (ent->cie)
{
/* CIE */
if (ent->make_relative
|| ent->u.cie.make_lsda_relative
|| ent->u.cie.per_encoding_relative)
{
char *aug;
unsigned int version, action, extra_string, extra_data;
unsigned int per_width, per_encoding;
/* Need to find 'R' or 'L' augmentation's argument and modify
DW_EH_PE_* value. */
action = ((ent->make_relative ? 1 : 0)
| (ent->u.cie.make_lsda_relative ? 2 : 0)
| (ent->u.cie.per_encoding_relative ? 4 : 0));
extra_string = extra_augmentation_string_bytes (ent);
extra_data = extra_augmentation_data_bytes (ent);
/* Skip length, id. */
buf += 8;
version = *buf++;
aug = (char *) buf;
buf += strlen (aug) + 1;
skip_leb128 (&buf, end);
skip_leb128 (&buf, end);
if (version == 1)
skip_bytes (&buf, end, 1);
else
skip_leb128 (&buf, end);
if (*aug == 'z')
{
/* The uleb128 will always be a single byte for the kind
of augmentation strings that we're prepared to handle. */
*buf++ += extra_data;
aug++;
}
/* Make room for the new augmentation string and data bytes. */
memmove (buf + extra_string + extra_data, buf, end - buf);
memmove (aug + extra_string, aug, buf - (bfd_byte *) aug);
buf += extra_string;
end += extra_string + extra_data;
if (ent->add_augmentation_size)
{
*aug++ = 'z';
*buf++ = extra_data - 1;
}
if (ent->u.cie.add_fde_encoding)
{
BFD_ASSERT (action & 1);
*aug++ = 'R';
*buf++ = make_pc_relative (DW_EH_PE_absptr, ptr_size);
action &= ~1;
}
while (action)
switch (*aug++)
{
case 'L':
if (action & 2)
{
BFD_ASSERT (*buf == ent->lsda_encoding);
*buf = make_pc_relative (*buf, ptr_size);
action &= ~2;
}
buf++;
break;
case 'P':
if (ent->u.cie.make_per_encoding_relative)
*buf = make_pc_relative (*buf, ptr_size);
per_encoding = *buf++;
per_width = get_DW_EH_PE_width (per_encoding, ptr_size);
BFD_ASSERT (per_width != 0);
BFD_ASSERT (((per_encoding & 0x70) == DW_EH_PE_pcrel)
== ent->u.cie.per_encoding_relative);
if ((per_encoding & 0x70) == DW_EH_PE_aligned)
buf = (contents
+ ((buf - contents + per_width - 1)
& ~((bfd_size_type) per_width - 1)));
if (action & 4)
{
bfd_vma val;
val = read_value (abfd, buf, per_width,
get_DW_EH_PE_signed (per_encoding));
if (ent->u.cie.make_per_encoding_relative)
val -= (sec->output_section->vma
+ sec->output_offset
+ (buf - contents));
else
{
val += (bfd_vma) ent->offset - ent->new_offset;
val -= extra_string + extra_data;
}
write_value (abfd, buf, val, per_width);
action &= ~4;
}
buf += per_width;
break;
case 'R':
if (action & 1)
{
BFD_ASSERT (*buf == ent->fde_encoding);
*buf = make_pc_relative (*buf, ptr_size);
action &= ~1;
}
buf++;
break;
case 'S':
break;
default:
BFD_FAIL ();
}
}
}
else
{
/* FDE */
bfd_vma value, address;
unsigned int width;
bfd_byte *start;
struct eh_cie_fde *cie;
/* Skip length. */
cie = ent->u.fde.cie_inf;
buf += 4;
value = ((ent->new_offset + sec->output_offset + 4)
- (cie->new_offset + cie->u.cie.u.sec->output_offset));
bfd_put_32 (abfd, value, buf);
if (bfd_link_relocatable (info))
continue;
buf += 4;
width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
value = read_value (abfd, buf, width,
get_DW_EH_PE_signed (ent->fde_encoding));
address = value;
if (value)
{
switch (ent->fde_encoding & 0x70)
{
case DW_EH_PE_textrel:
BFD_ASSERT (hdr_info == NULL);
break;
case DW_EH_PE_datarel:
{
switch (abfd->arch_info->arch)
{
case bfd_arch_ia64:
BFD_ASSERT (elf_gp (abfd) != 0);
address += elf_gp (abfd);
break;
default:
_bfd_error_handler
(_("DW_EH_PE_datarel unspecified"
" for this architecture"));
/* Fall thru */
case bfd_arch_frv:
case bfd_arch_i386:
case bfd_arch_nios2:
BFD_ASSERT (htab->hgot != NULL
&& ((htab->hgot->root.type
== bfd_link_hash_defined)
|| (htab->hgot->root.type
== bfd_link_hash_defweak)));
address
+= (htab->hgot->root.u.def.value
+ htab->hgot->root.u.def.section->output_offset
+ (htab->hgot->root.u.def.section->output_section
->vma));
break;
}
}
break;
case DW_EH_PE_pcrel:
value += (bfd_vma) ent->offset - ent->new_offset;
address += (sec->output_section->vma
+ sec->output_offset
+ ent->offset + 8);
break;
}
if (ent->make_relative)
value -= (sec->output_section->vma
+ sec->output_offset
+ ent->new_offset + 8);
write_value (abfd, buf, value, width);
}
start = buf;
if (hdr_info)
{
/* The address calculation may overflow, giving us a
value greater than 4G on a 32-bit target when
dwarf_vma is 64-bit. */
if (sizeof (address) > 4 && ptr_size == 4)
address &= 0xffffffff;
hdr_info->u.dwarf.array[hdr_info->array_count].initial_loc
= address;
hdr_info->u.dwarf.array[hdr_info->array_count].range
= read_value (abfd, buf + width, width, false);
hdr_info->u.dwarf.array[hdr_info->array_count++].fde
= (sec->output_section->vma
+ sec->output_offset
+ ent->new_offset);
}
if ((ent->lsda_encoding & 0x70) == DW_EH_PE_pcrel
|| cie->u.cie.make_lsda_relative)
{
buf += ent->lsda_offset;
width = get_DW_EH_PE_width (ent->lsda_encoding, ptr_size);
value = read_value (abfd, buf, width,
get_DW_EH_PE_signed (ent->lsda_encoding));
if (value)
{
if ((ent->lsda_encoding & 0x70) == DW_EH_PE_pcrel)
value += (bfd_vma) ent->offset - ent->new_offset;
else if (cie->u.cie.make_lsda_relative)
value -= (sec->output_section->vma
+ sec->output_offset
+ ent->new_offset + 8 + ent->lsda_offset);
write_value (abfd, buf, value, width);
}
}
else if (ent->add_augmentation_size)
{
/* Skip the PC and length and insert a zero byte for the
augmentation size. */
buf += width * 2;
memmove (buf + 1, buf, end - buf);
*buf = 0;
}
if (ent->set_loc)
{
/* Adjust DW_CFA_set_loc. */
unsigned int cnt;
bfd_vma new_offset;
width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
new_offset = ent->new_offset + 8
+ extra_augmentation_string_bytes (ent)
+ extra_augmentation_data_bytes (ent);
for (cnt = 1; cnt <= ent->set_loc[0]; cnt++)
{
buf = start + ent->set_loc[cnt];
value = read_value (abfd, buf, width,
get_DW_EH_PE_signed (ent->fde_encoding));
if (!value)
continue;
if ((ent->fde_encoding & 0x70) == DW_EH_PE_pcrel)
value += (bfd_vma) ent->offset + 8 - new_offset;
if (ent->make_relative)
value -= (sec->output_section->vma
+ sec->output_offset
+ new_offset + ent->set_loc[cnt]);
write_value (abfd, buf, value, width);
}
}
}
}
/* FIXME: octets_per_byte. */
return bfd_set_section_contents (abfd, sec->output_section,
contents, (file_ptr) sec->output_offset,
sec->size);
}
/* Helper function used to sort .eh_frame_hdr search table by increasing
VMA of FDE initial location. */
static int
vma_compare (const void *a, const void *b)
{
const struct eh_frame_array_ent *p = (const struct eh_frame_array_ent *) a;
const struct eh_frame_array_ent *q = (const struct eh_frame_array_ent *) b;
if (p->initial_loc > q->initial_loc)
return 1;
if (p->initial_loc < q->initial_loc)
return -1;
if (p->range > q->range)
return 1;
if (p->range < q->range)
return -1;
return 0;
}
/* Reorder .eh_frame_entry sections to match the associated text sections.
This routine is called during the final linking step, just before writing
the contents. At this stage, sections in the eh_frame_hdr_info are already
sorted in order of increasing text section address and so we simply need
to make the .eh_frame_entrys follow that same order. Note that it is
invalid for a linker script to try to force a particular order of
.eh_frame_entry sections. */
bool
_bfd_elf_fixup_eh_frame_hdr (struct bfd_link_info *info)
{
asection *sec = NULL;
asection *osec;
struct eh_frame_hdr_info *hdr_info;
unsigned int i;
bfd_vma offset;
struct bfd_link_order *p;
hdr_info = &elf_hash_table (info)->eh_info;
if (hdr_info->hdr_sec == NULL
|| info->eh_frame_hdr_type != COMPACT_EH_HDR
|| hdr_info->array_count == 0)
return true;
/* Change section output offsets to be in text section order. */
offset = 8;
osec = hdr_info->u.compact.entries[0]->output_section;
for (i = 0; i < hdr_info->array_count; i++)
{
sec = hdr_info->u.compact.entries[i];
if (sec->output_section != osec)
{
_bfd_error_handler
(_("invalid output section for .eh_frame_entry: %pA"),
sec->output_section);
return false;
}
sec->output_offset = offset;
offset += sec->size;
}
/* Fix the link_order to match. */
for (p = sec->output_section->map_head.link_order; p != NULL; p = p->next)
{
if (p->type != bfd_indirect_link_order)
abort();
p->offset = p->u.indirect.section->output_offset;
if (p->next != NULL)
i--;
}
if (i != 0)
{
_bfd_error_handler
(_("invalid contents in %pA section"), osec);
return false;
}
return true;
}
/* The .eh_frame_hdr format for Compact EH frames:
ubyte version (2)
ubyte eh_ref_enc (DW_EH_PE_* encoding of typinfo references)
uint32_t count (Number of entries in table)
[array from .eh_frame_entry sections] */
static bool
write_compact_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
{
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
asection *sec;
const struct elf_backend_data *bed;
bfd_vma count;
bfd_byte contents[8];
unsigned int i;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
sec = hdr_info->hdr_sec;
if (sec->size != 8)
abort();
for (i = 0; i < sizeof (contents); i++)
contents[i] = 0;
contents[0] = COMPACT_EH_HDR;
bed = get_elf_backend_data (abfd);
BFD_ASSERT (bed->compact_eh_encoding);
contents[1] = (*bed->compact_eh_encoding) (info);
count = (sec->output_section->size - 8) / 8;
bfd_put_32 (abfd, count, contents + 4);
return bfd_set_section_contents (abfd, sec->output_section, contents,
(file_ptr) sec->output_offset, sec->size);
}
/* The .eh_frame_hdr format for DWARF frames:
ubyte version (currently 1)
ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of
.eh_frame section)
ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count
number (or DW_EH_PE_omit if there is no
binary search table computed))
ubyte table_enc (DW_EH_PE_* encoding of binary search table,
or DW_EH_PE_omit if not present.
DW_EH_PE_datarel is using address of
.eh_frame_hdr section start as base)
[encoded] eh_frame_ptr (pointer to start of .eh_frame section)
optionally followed by:
[encoded] fde_count (total number of FDEs in .eh_frame section)
fde_count x [encoded] initial_loc, fde
(array of encoded pairs containing
FDE initial_location field and FDE address,
sorted by increasing initial_loc). */
static bool
write_dwarf_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
{
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
asection *sec;
bool retval = true;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
sec = hdr_info->hdr_sec;
bfd_byte *contents;
asection *eh_frame_sec;
bfd_size_type size;
bfd_vma encoded_eh_frame;
size = EH_FRAME_HDR_SIZE;
if (hdr_info->u.dwarf.array
&& hdr_info->array_count == hdr_info->u.dwarf.fde_count)
size += 4 + hdr_info->u.dwarf.fde_count * 8;
contents = (bfd_byte *) bfd_malloc (size);
if (contents == NULL)
return false;
eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame");
if (eh_frame_sec == NULL)
{
free (contents);
return false;
}
memset (contents, 0, EH_FRAME_HDR_SIZE);
/* Version. */
contents[0] = 1;
/* .eh_frame offset. */
contents[1] = get_elf_backend_data (abfd)->elf_backend_encode_eh_address
(abfd, info, eh_frame_sec, 0, sec, 4, &encoded_eh_frame);
if (hdr_info->u.dwarf.array
&& hdr_info->array_count == hdr_info->u.dwarf.fde_count)
{
/* FDE count encoding. */
contents[2] = DW_EH_PE_udata4;
/* Search table encoding. */
contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
}
else
{
contents[2] = DW_EH_PE_omit;
contents[3] = DW_EH_PE_omit;
}
bfd_put_32 (abfd, encoded_eh_frame, contents + 4);
if (contents[2] != DW_EH_PE_omit)
{
unsigned int i;
bool overlap, overflow;
bfd_put_32 (abfd, hdr_info->u.dwarf.fde_count,
contents + EH_FRAME_HDR_SIZE);
qsort (hdr_info->u.dwarf.array, hdr_info->u.dwarf.fde_count,
sizeof (*hdr_info->u.dwarf.array), vma_compare);
overlap = false;
overflow = false;
for (i = 0; i < hdr_info->u.dwarf.fde_count; i++)
{
bfd_vma val;
val = hdr_info->u.dwarf.array[i].initial_loc
- sec->output_section->vma;
val = ((val & 0xffffffff) ^ 0x80000000) - 0x80000000;
if (elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64
&& (hdr_info->u.dwarf.array[i].initial_loc
!= sec->output_section->vma + val))
overflow = true;
bfd_put_32 (abfd, val, contents + EH_FRAME_HDR_SIZE + i * 8 + 4);
val = hdr_info->u.dwarf.array[i].fde - sec->output_section->vma;
val = ((val & 0xffffffff) ^ 0x80000000) - 0x80000000;
if (elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64
&& (hdr_info->u.dwarf.array[i].fde
!= sec->output_section->vma + val))
overflow = true;
bfd_put_32 (abfd, val, contents + EH_FRAME_HDR_SIZE + i * 8 + 8);
if (i != 0
&& (hdr_info->u.dwarf.array[i].initial_loc
< (hdr_info->u.dwarf.array[i - 1].initial_loc
+ hdr_info->u.dwarf.array[i - 1].range)))
overlap = true;
}
if (overflow)
_bfd_error_handler (_(".eh_frame_hdr entry overflow"));
if (overlap)
_bfd_error_handler (_(".eh_frame_hdr refers to overlapping FDEs"));
if (overflow || overlap)
{
bfd_set_error (bfd_error_bad_value);
retval = false;
}
}
/* FIXME: octets_per_byte. */
if (!bfd_set_section_contents (abfd, sec->output_section, contents,
(file_ptr) sec->output_offset,
sec->size))
retval = false;
free (contents);
free (hdr_info->u.dwarf.array);
return retval;
}
/* Write out .eh_frame_hdr section. This must be called after
_bfd_elf_write_section_eh_frame has been called on all input
.eh_frame sections. */
bool
_bfd_elf_write_section_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
{
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
asection *sec;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
sec = hdr_info->hdr_sec;
if (info->eh_frame_hdr_type == 0 || sec == NULL)
return true;
if (info->eh_frame_hdr_type == COMPACT_EH_HDR)
return write_compact_eh_frame_hdr (abfd, info);
else
return write_dwarf_eh_frame_hdr (abfd, info);
}
/* Return the width of FDE addresses. This is the default implementation. */
unsigned int
_bfd_elf_eh_frame_address_size (bfd *abfd, const asection *sec ATTRIBUTE_UNUSED)
{
return elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64 ? 8 : 4;
}
/* Decide whether we can use a PC-relative encoding within the given
EH frame section. This is the default implementation. */
bool
_bfd_elf_can_make_relative (bfd *input_bfd ATTRIBUTE_UNUSED,
struct bfd_link_info *info ATTRIBUTE_UNUSED,
asection *eh_frame_section ATTRIBUTE_UNUSED)
{
return true;
}
/* Select an encoding for the given address. Preference is given to
PC-relative addressing modes. */
bfd_byte
_bfd_elf_encode_eh_address (bfd *abfd ATTRIBUTE_UNUSED,
struct bfd_link_info *info ATTRIBUTE_UNUSED,
asection *osec, bfd_vma offset,
asection *loc_sec, bfd_vma loc_offset,
bfd_vma *encoded)
{
*encoded = osec->vma + offset -
(loc_sec->output_section->vma + loc_sec->output_offset + loc_offset);
return DW_EH_PE_pcrel | DW_EH_PE_sdata4;
}