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binutils-gdb/bfd/elf-eh-frame.c

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/* .eh_frame section optimization.
Copyright 2001, 2002, 2003, 2004, 2005, 2006 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 2 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 "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "elf/dwarf2.h"
#define EH_FRAME_HDR_SIZE 8
struct cie
{
unsigned int length;
unsigned int hash;
unsigned char version;
char augmentation[20];
bfd_vma code_align;
bfd_signed_vma data_align;
bfd_vma ra_column;
bfd_vma augmentation_size;
struct elf_link_hash_entry *personality;
asection *output_sec;
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 make_relative;
unsigned char 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 bfd_boolean
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 bfd_boolean
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 bfd_boolean
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 bfd_boolean
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 bfd_boolean
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 = e1;
const struct cie *c2 = e2;
if (c1->hash == c2->hash
&& c1->length == c2->length
&& c1->version == c2->version
&& 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
&& c1->personality == c2->personality
&& c1->output_sec == c2->output_sec
&& 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
&& 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 = e;
return c->hash;
}
static hashval_t
cie_compute_hash (struct cie *c)
{
hashval_t h = 0;
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->output_sec, 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);
h = iterative_hash (c->initial_instructions, c->initial_insn_length, 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->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->cie)
{
if (entry->add_augmentation_size)
size++;
if (entry->add_fde_encoding)
size++;
}
else
{
if (entry->cie_inf->add_augmentation_size)
size++;
}
return size;
}
/* Return the size that ENTRY will have in the output. ALIGNMENT is the
required alignment of ENTRY in bytes. */
static unsigned int
size_of_output_cie_fde (struct eh_cie_fde *entry, unsigned int alignment)
{
if (entry->removed)
return 0;
if (entry->size == 4)
return 4;
return (entry->size
+ extra_augmentation_string_bytes (entry)
+ extra_augmentation_data_bytes (entry)
+ alignment - 1) & -alignment;
}
/* 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 bfd_boolean
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;
}
/* 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. */
bfd_boolean
_bfd_elf_discard_section_eh_frame
(bfd *abfd, struct bfd_link_info *info, asection *sec,
bfd_boolean (*reloc_symbol_deleted_p) (bfd_vma, void *),
struct elf_reloc_cookie *cookie)
{
#define REQUIRE(COND) \
do \
if (!(COND)) \
goto free_no_table; \
while (0)
bfd_byte *ehbuf = NULL, *buf;
bfd_byte *last_fde;
struct eh_cie_fde *ent, *this_inf;
unsigned int hdr_length, hdr_id;
struct extended_cie
{
struct cie cie;
unsigned int offset;
unsigned int usage_count;
unsigned int entry;
} *ecies = NULL, *ecie;
unsigned int ecie_count = 0, ecie_alloced = 0;
struct cie *cie;
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
struct eh_frame_sec_info *sec_info = NULL;
unsigned int offset;
unsigned int ptr_size;
unsigned int entry_alloced;
if (sec->size == 0)
{
/* This file does not contain .eh_frame information. */
return FALSE;
}
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 FALSE;
}
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (hdr_info->cies == NULL && !info->relocatable)
hdr_info->cies = htab_try_create (1, cie_hash, cie_eq, free);
/* Read the frame unwind information from abfd. */
REQUIRE (bfd_malloc_and_get_section (abfd, sec, &ehbuf));
if (sec->size >= 4
&& bfd_get_32 (abfd, ehbuf) == 0
&& cookie->rel == cookie->relend)
{
/* Empty .eh_frame section. */
free (ehbuf);
return FALSE;
}
/* 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);
buf = ehbuf;
sec_info = bfd_zmalloc (sizeof (struct eh_frame_sec_info)
+ 99 * sizeof (struct eh_cie_fde));
REQUIRE (sec_info);
entry_alloced = 100;
#define ENSURE_NO_RELOCS(buf) \
REQUIRE (!(cookie->rel < cookie->relend \
&& (cookie->rel->r_offset \
< (bfd_size_type) ((buf) - ehbuf)) \
&& cookie->rel->r_info != 0))
#define SKIP_RELOCS(buf) \
while (cookie->rel < cookie->relend \
&& (cookie->rel->r_offset \
< (bfd_size_type) ((buf) - ehbuf))) \
cookie->rel++
#define GET_RELOC(buf) \
((cookie->rel < cookie->relend \
&& (cookie->rel->r_offset \
== (bfd_size_type) ((buf) - ehbuf))) \
? cookie->rel : NULL)
for (;;)
{
char *aug;
bfd_byte *start, *end, *insns, *insns_end;
bfd_size_type length;
unsigned int set_loc_count;
if (sec_info->count == entry_alloced)
{
sec_info = bfd_realloc (sec_info,
sizeof (struct eh_frame_sec_info)
+ ((entry_alloced + 99)
* sizeof (struct eh_cie_fde)));
REQUIRE (sec_info);
memset (&sec_info->entry[entry_alloced], 0,
100 * sizeof (struct eh_cie_fde));
entry_alloced += 100;
}
this_inf = sec_info->entry + sec_info->count;
last_fde = buf;
if ((bfd_size_type) (buf - ehbuf) == sec->size)
break;
/* Read the length of the entry. */
REQUIRE (skip_bytes (&buf, ehbuf + sec->size, 4));
hdr_length = bfd_get_32 (abfd, buf - 4);
/* 64-bit .eh_frame is not supported. */
REQUIRE (hdr_length != 0xffffffff);
/* 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;
if (hdr_length == 0)
{
/* A zero-length CIE should only be found at the end of
the section. */
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;
if (ecie_count == ecie_alloced)
{
ecies = bfd_realloc (ecies,
(ecie_alloced + 20) * sizeof (*ecies));
REQUIRE (ecies);
memset (&ecies[ecie_alloced], 0, 20 * sizeof (*ecies));
ecie_alloced += 20;
}
cie = &ecies[ecie_count].cie;
ecies[ecie_count].offset = this_inf->offset;
ecies[ecie_count++].entry = sec_info->count;
cie->length = hdr_length;
start = buf;
REQUIRE (read_byte (&buf, end, &cie->version));
/* Cannot handle unknown versions. */
REQUIRE (cie->version == 1 || cie->version == 3);
REQUIRE (strlen ((char *) buf) < sizeof (cie->augmentation));
strcpy (cie->augmentation, (char *) buf);
buf = (bfd_byte *) strchr ((char *) buf, '\0') + 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);
}
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 '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 & 0xf0) == DW_EH_PE_aligned)
{
length = -(buf - ehbuf) & (per_width - 1);
REQUIRE (skip_bytes (&buf, end, length));
}
ENSURE_NO_RELOCS (buf);
/* Ensure we have a reloc here, against
a global symbol. */
if (GET_RELOC (buf) != NULL)
{
unsigned long r_symndx;
#ifdef BFD64
if (ptr_size == 8)
r_symndx = ELF64_R_SYM (cookie->rel->r_info);
else
#endif
r_symndx = ELF32_R_SYM (cookie->rel->r_info);
if (r_symndx >= cookie->locsymcount)
{
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;
}
/* Cope with MIPS-style composite relocations. */
do
cookie->rel++;
while (GET_RELOC (buf) != NULL);
}
REQUIRE (skip_bytes (&buf, end, per_width));
REQUIRE (cie->personality);
}
break;
default:
/* Unrecognized augmentation. Better bail out. */
goto free_no_table;
}
}
/* For shared libraries, try to get rid of as many RELATIVE relocs
as possible. */
if (info->shared
&& (get_elf_backend_data (abfd)
->elf_backend_can_make_relative_eh_frame
(abfd, info, sec)))
{
if ((cie->fde_encoding & 0xf0) == DW_EH_PE_absptr)
cie->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 & 0xf0) != DW_EH_PE_aligned)
{
if (*cie->augmentation == 0)
this_inf->add_augmentation_size = 1;
this_inf->add_fde_encoding = 1;
cie->make_relative = 1;
}
}
if (info->shared
&& (get_elf_backend_data (abfd)
->elf_backend_can_make_lsda_relative_eh_frame
(abfd, info, sec))
&& (cie->lsda_encoding & 0xf0) == DW_EH_PE_absptr)
cie->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;
if (initial_insn_length <= sizeof (cie->initial_instructions))
{
cie->initial_insn_length = initial_insn_length;
memcpy (cie->initial_instructions, buf, initial_insn_length);
}
insns = buf;
buf += initial_insn_length;
ENSURE_NO_RELOCS (buf);
}
else
{
/* Find the corresponding CIE. */
unsigned int cie_offset = this_inf->offset + 4 - hdr_id;
for (ecie = ecies; ecie < ecies + ecie_count; ++ecie)
if (cie_offset == ecie->offset)
break;
/* Ensure this FDE references one of the CIEs in this input
section. */
REQUIRE (ecie != ecies + ecie_count);
cie = &ecie->cie;
ENSURE_NO_RELOCS (buf);
REQUIRE (GET_RELOC (buf));
if ((*reloc_symbol_deleted_p) (buf - ehbuf, cookie))
/* This is a FDE against a discarded section. It should
be deleted. */
this_inf->removed = 1;
else
{
if (info->shared
&& (((cie->fde_encoding & 0xf0) == DW_EH_PE_absptr
&& cie->make_relative == 0)
|| (cie->fde_encoding & 0xf0) == DW_EH_PE_aligned))
{
/* 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->table = FALSE;
}
ecie->usage_count++;
hdr_info->fde_count++;
this_inf->cie_inf = (void *) (ecie - ecies);
}
/* 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 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)
{
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;
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 & 0xf0) == DW_EH_PE_pcrel
|| cie->make_relative))
{
unsigned int cnt;
bfd_byte *p;
this_inf->set_loc = 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->fde_encoding = cie->fde_encoding;
this_inf->lsda_encoding = cie->lsda_encoding;
sec_info->count++;
}
elf_section_data (sec)->sec_info = sec_info;
sec->sec_info_type = ELF_INFO_TYPE_EH_FRAME;
/* Look at all CIEs in this section and determine which can be
removed as unused, which can be merged with previous duplicate
CIEs and which need to be kept. */
for (ecie = ecies; ecie < ecies + ecie_count; ++ecie)
{
if (ecie->usage_count == 0)
{
sec_info->entry[ecie->entry].removed = 1;
continue;
}
ecie->cie.output_sec = sec->output_section;
ecie->cie.cie_inf = sec_info->entry + ecie->entry;
cie_compute_hash (&ecie->cie);
if (hdr_info->cies != NULL)
{
void **loc = htab_find_slot_with_hash (hdr_info->cies, &ecie->cie,
ecie->cie.hash, INSERT);
if (loc != NULL)
{
if (*loc != HTAB_EMPTY_ENTRY)
{
sec_info->entry[ecie->entry].removed = 1;
ecie->cie.cie_inf = ((struct cie *) *loc)->cie_inf;
continue;
}
*loc = malloc (sizeof (struct cie));
if (*loc == NULL)
*loc = HTAB_DELETED_ENTRY;
else
memcpy (*loc, &ecie->cie, sizeof (struct cie));
}
}
ecie->cie.cie_inf->make_relative = ecie->cie.make_relative;
ecie->cie.cie_inf->make_lsda_relative = ecie->cie.make_lsda_relative;
ecie->cie.cie_inf->per_encoding_relative
= (ecie->cie.per_encoding & 0x70) == DW_EH_PE_pcrel;
}
/* Ok, now we can assign new offsets. */
offset = 0;
for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
if (!ent->removed)
{
if (!ent->cie)
{
ecie = ecies + (unsigned long) ent->cie_inf;
ent->cie_inf = ecie->cie.cie_inf;
}
ent->new_offset = offset;
offset += size_of_output_cie_fde (ent, ptr_size);
}
/* Resize the sec as needed. */
sec->rawsize = sec->size;
sec->size = offset;
if (sec->size == 0)
sec->flags |= SEC_EXCLUDE;
free (ehbuf);
if (ecies)
free (ecies);
return offset != sec->rawsize;
free_no_table:
if (ehbuf)
free (ehbuf);
if (sec_info)
free (sec_info);
if (ecies)
free (ecies);
hdr_info->table = FALSE;
return FALSE;
#undef REQUIRE
}
/* 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. */
bfd_boolean
_bfd_elf_discard_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;
if (hdr_info->cies != NULL)
{
htab_delete (hdr_info->cies);
hdr_info->cies = NULL;
}
sec = hdr_info->hdr_sec;
if (sec == NULL)
return FALSE;
sec->size = EH_FRAME_HDR_SIZE;
if (hdr_info->table)
sec->size += 4 + hdr_info->fde_count * 8;
elf_tdata (abfd)->eh_frame_hdr = sec;
return TRUE;
}
/* 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. */
bfd_boolean
_bfd_elf_maybe_strip_eh_frame_hdr (struct bfd_link_info *info)
{
asection *o;
bfd *abfd;
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
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))
{
hdr_info->hdr_sec = NULL;
return TRUE;
}
abfd = NULL;
if (info->eh_frame_hdr)
for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
{
/* Count only sections which have at least a single CIE or FDE.
There cannot be any CIE or FDE <= 8 bytes. */
o = bfd_get_section_by_name (abfd, ".eh_frame");
if (o && o->size > 8 && !bfd_is_abs_section (o->output_section))
break;
}
if (abfd == NULL)
{
hdr_info->hdr_sec->flags |= SEC_EXCLUDE;
hdr_info->hdr_sec = NULL;
return TRUE;
}
hdr_info->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,
asection *sec,
bfd_vma offset)
{
struct eh_frame_sec_info *sec_info;
struct elf_link_hash_table *htab;
struct eh_frame_hdr_info *hdr_info;
unsigned int lo, hi, mid;
if (sec->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
return offset;
sec_info = elf_section_data (sec)->sec_info;
if (offset >= sec->rawsize)
return offset - sec->rawsize + sec->size;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
if (hdr_info->offsets_adjusted)
offset += sec->output_offset;
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 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].cie_inf->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].cie_inf->make_lsda_relative
&& (offset == (sec_info->entry[mid].offset + 8
+ sec_info->entry[mid].lsda_offset))
&& (sec_info->entry[mid].cie_inf->need_lsda_relative
|| !hdr_info->offsets_adjusted))
{
sec_info->entry[mid].cie_inf->need_lsda_relative = 1;
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].cie
? sec_info->entry[mid].make_relative
: sec_info->entry[mid].cie_inf->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;
}
if (hdr_info->offsets_adjusted)
offset -= sec->output_offset;
/* 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 section. This is called with the relocated
contents. */
bfd_boolean
_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;
if (sec->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
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 = elf_section_data (sec)->sec_info;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
/* First convert all offsets to output section offsets, so that a
CIE offset is valid if the CIE is used by a FDE from some other
section. This can happen when duplicate CIEs are deleted in
_bfd_elf_discard_section_eh_frame. We do all sections here because
this function might not be called on sections in the same order as
_bfd_elf_discard_section_eh_frame. */
if (!hdr_info->offsets_adjusted)
{
bfd *ibfd;
asection *eh;
struct eh_frame_sec_info *eh_inf;
for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link_next)
{
if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
|| (ibfd->flags & DYNAMIC) != 0)
continue;
eh = bfd_get_section_by_name (ibfd, ".eh_frame");
if (eh == NULL || eh->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
continue;
eh_inf = elf_section_data (eh)->sec_info;
for (ent = eh_inf->entry; ent < eh_inf->entry + eh_inf->count; ++ent)
{
ent->offset += eh->output_offset;
ent->new_offset += eh->output_offset;
}
}
hdr_info->offsets_adjusted = TRUE;
}
if (hdr_info->table && hdr_info->array == NULL)
hdr_info->array
= bfd_malloc (hdr_info->fde_count * sizeof(*hdr_info->array));
if (hdr_info->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 - sec->output_offset,
contents + ent->offset - sec->output_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 - sec->output_offset,
contents + ent->offset - sec->output_offset, ent->size);
for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++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 == sec_info->entry + sec_info->count - 1);
continue;
}
buf = contents + ent->new_offset - sec->output_offset;
end = buf + ent->size;
new_size = size_of_output_cie_fde (ent, ptr_size);
/* 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->need_lsda_relative
|| ent->per_encoding_relative)
{
char *aug;
unsigned int 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->need_lsda_relative ? 2 : 0)
| (ent->per_encoding_relative ? 4 : 0));
extra_string = extra_augmentation_string_bytes (ent);
extra_data = extra_augmentation_data_bytes (ent);
/* Skip length, id and version. */
buf += 9;
aug = (char *) buf;
buf += strlen (aug) + 1;
skip_leb128 (&buf, end);
skip_leb128 (&buf, end);
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->add_fde_encoding)
{
BFD_ASSERT (action & 1);
*aug++ = 'R';
*buf++ = DW_EH_PE_pcrel;
action &= ~1;
}
while (action)
switch (*aug++)
{
case 'L':
if (action & 2)
{
BFD_ASSERT (*buf == ent->lsda_encoding);
*buf |= DW_EH_PE_pcrel;
action &= ~2;
}
buf++;
break;
case 'P':
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->per_encoding_relative);
if ((per_encoding & 0xf0) == 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));
val += 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 |= DW_EH_PE_pcrel;
action &= ~1;
}
buf++;
break;
case 'S':
break;
default:
BFD_FAIL ();
}
}
}
else
{
/* FDE */
bfd_vma value, address;
unsigned int width;
bfd_byte *start;
/* Skip length. */
buf += 4;
value = ent->new_offset + 4 - ent->cie_inf->new_offset;
bfd_put_32 (abfd, value, buf);
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 & 0xf0)
{
case DW_EH_PE_indirect:
case DW_EH_PE_textrel:
BFD_ASSERT (hdr_info == NULL);
break;
case DW_EH_PE_datarel:
{
asection *got = bfd_get_section_by_name (abfd, ".got");
BFD_ASSERT (got != NULL);
address += got->vma;
}
break;
case DW_EH_PE_pcrel:
value += ent->offset - ent->new_offset;
address += sec->output_section->vma + ent->offset + 8;
break;
}
if (ent->cie_inf->make_relative)
value -= sec->output_section->vma + ent->new_offset + 8;
write_value (abfd, buf, value, width);
}
start = buf;
if (hdr_info)
{
hdr_info->array[hdr_info->array_count].initial_loc = address;
hdr_info->array[hdr_info->array_count++].fde
= sec->output_section->vma + ent->new_offset;
}
if ((ent->lsda_encoding & 0xf0) == DW_EH_PE_pcrel
|| ent->cie_inf->need_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 & 0xf0) == DW_EH_PE_pcrel)
value += ent->offset - ent->new_offset;
else if (ent->cie_inf->need_lsda_relative)
value -= (sec->output_section->vma + ent->new_offset + 8
+ ent->lsda_offset);
write_value (abfd, buf, value, width);
}
}
else if (ent->cie_inf->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, width;
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++)
{
bfd_vma value;
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 & 0xf0) == DW_EH_PE_pcrel)
value += ent->offset + 8 - new_offset;
if (ent->cie_inf->make_relative)
value -= sec->output_section->vma + new_offset
+ ent->set_loc[cnt];
write_value (abfd, buf, value, width);
}
}
}
}
/* We don't align the section to its section alignment since the
runtime library only expects all CIE/FDE records aligned at
the pointer size. _bfd_elf_discard_section_eh_frame should
have padded CIE/FDE records to multiple of pointer size with
size_of_output_cie_fde. */
if ((sec->size % ptr_size) != 0)
abort ();
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 = a;
const struct eh_frame_array_ent *q = b;
if (p->initial_loc > q->initial_loc)
return 1;
if (p->initial_loc < q->initial_loc)
return -1;
return 0;
}
/* 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.
.eh_frame_hdr format:
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). */
bfd_boolean
_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;
bfd_byte *contents;
asection *eh_frame_sec;
bfd_size_type size;
bfd_boolean retval;
bfd_vma encoded_eh_frame;
htab = elf_hash_table (info);
hdr_info = &htab->eh_info;
sec = hdr_info->hdr_sec;
if (sec == NULL)
return TRUE;
size = EH_FRAME_HDR_SIZE;
if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
size += 4 + hdr_info->fde_count * 8;
contents = 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);
contents[0] = 1; /* Version. */
contents[1] = get_elf_backend_data (abfd)->elf_backend_encode_eh_address
(abfd, info, eh_frame_sec, 0, sec, 4,
&encoded_eh_frame); /* .eh_frame offset. */
if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
{
contents[2] = DW_EH_PE_udata4; /* FDE count encoding. */
contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4; /* Search table enc. */
}
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;
bfd_put_32 (abfd, hdr_info->fde_count, contents + EH_FRAME_HDR_SIZE);
qsort (hdr_info->array, hdr_info->fde_count, sizeof (*hdr_info->array),
vma_compare);
for (i = 0; i < hdr_info->fde_count; i++)
{
bfd_put_32 (abfd,
hdr_info->array[i].initial_loc
- sec->output_section->vma,
contents + EH_FRAME_HDR_SIZE + i * 8 + 4);
bfd_put_32 (abfd,
hdr_info->array[i].fde - sec->output_section->vma,
contents + EH_FRAME_HDR_SIZE + i * 8 + 8);
}
}
retval = bfd_set_section_contents (abfd, sec->output_section,
contents, (file_ptr) sec->output_offset,
sec->size);
free (contents);
return retval;
}
/* Return the width of FDE addresses. This is the default implementation. */
unsigned int
_bfd_elf_eh_frame_address_size (bfd *abfd, 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. */
bfd_boolean
_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;
}
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