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/* X86-64 specific support for 64-bit ELF
Copyright 2000, 2001 Free Software Foundation, Inc.
Contributed by Jan Hubicka <jh@suse.cz>.
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "elf/x86-64.h"
/* We use only the RELA entries. */
#define USE_RELA
/* In case we're on a 32-bit machine, construct a 64-bit "-1" value. */
#define MINUS_ONE (~ (bfd_vma) 0)
/* The relocation "howto" table. Order of fields:
type, size, bitsize, pc_relative, complain_on_overflow,
special_function, name, partial_inplace, src_mask, dst_pack, pcrel_offset. */
static reloc_howto_type x86_64_elf_howto_table[] =
{
HOWTO(R_X86_64_NONE, 0, 0, 0, false, 0, complain_overflow_dont,
bfd_elf_generic_reloc, "R_X86_64_NONE", false, 0x00000000, 0x00000000,
false),
HOWTO(R_X86_64_64, 0, 4, 64, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_64", false, MINUS_ONE, MINUS_ONE,
false),
HOWTO(R_X86_64_PC32, 0, 4, 32, true, 0, complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_PC32", false, 0xffffffff, 0xffffffff,
true),
HOWTO(R_X86_64_GOT32, 0, 4, 32, false, 0, complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_GOT32", false, 0xffffffff, 0xffffffff,
false),
HOWTO(R_X86_64_PLT32, 0, 4, 32, true, 0, complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_PLT32", false, 0xffffffff, 0xffffffff,
true),
HOWTO(R_X86_64_COPY, 0, 4, 32, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_COPY", false, 0xffffffff, 0xffffffff,
false),
HOWTO(R_X86_64_GLOB_DAT, 0, 4, 64, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_GLOB_DAT", false, MINUS_ONE,
MINUS_ONE, false),
HOWTO(R_X86_64_JUMP_SLOT, 0, 4, 64, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_JUMP_SLOT", false, MINUS_ONE,
MINUS_ONE, false),
HOWTO(R_X86_64_RELATIVE, 0, 4, 64, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_RELATIVE", false, MINUS_ONE,
MINUS_ONE, false),
HOWTO(R_X86_64_GOTPCREL, 0, 4, 32, true,0 , complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_GOTPCREL", false, 0xffffffff,
0xffffffff, true),
HOWTO(R_X86_64_32, 0, 4, 32, false, 0, complain_overflow_unsigned,
bfd_elf_generic_reloc, "R_X86_64_32", false, 0xffffffff, 0xffffffff,
false),
HOWTO(R_X86_64_32S, 0, 4, 32, false, 0, complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_32S", false, 0xffffffff, 0xffffffff,
false),
HOWTO(R_X86_64_16, 0, 1, 16, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_16", false, 0xffff, 0xffff, false),
HOWTO(R_X86_64_PC16,0, 1, 16, true, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_PC16", false, 0xffff, 0xffff, true),
HOWTO(R_X86_64_8, 0, 0, 8, false, 0, complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_8", false, 0xff, 0xff, false),
HOWTO(R_X86_64_PC8, 0, 0, 8, true, 0, complain_overflow_signed,
bfd_elf_generic_reloc, "R_X86_64_PC8", false, 0xff, 0xff, true),
/* GNU extension to record C++ vtable hierarchy. */
HOWTO (R_X86_64_GNU_VTINHERIT, 0, 4, 0, false, 0, complain_overflow_dont,
NULL, "R_X86_64_GNU_VTINHERIT", false, 0, 0, false),
/* GNU extension to record C++ vtable member usage. */
HOWTO (R_X86_64_GNU_VTENTRY, 0, 4, 0, false, 0, complain_overflow_dont,
_bfd_elf_rel_vtable_reloc_fn, "R_X86_64_GNU_VTENTRY", false, 0, 0,
false)
};
/* Map BFD relocs to the x86_64 elf relocs. */
struct elf_reloc_map
{
bfd_reloc_code_real_type bfd_reloc_val;
unsigned char elf_reloc_val;
};
static const struct elf_reloc_map x86_64_reloc_map[] =
{
{ BFD_RELOC_NONE, R_X86_64_NONE, },
{ BFD_RELOC_64, R_X86_64_64, },
{ BFD_RELOC_32_PCREL, R_X86_64_PC32, },
{ BFD_RELOC_X86_64_GOT32, R_X86_64_GOT32,},
{ BFD_RELOC_X86_64_PLT32, R_X86_64_PLT32,},
{ BFD_RELOC_X86_64_COPY, R_X86_64_COPY, },
{ BFD_RELOC_X86_64_GLOB_DAT, R_X86_64_GLOB_DAT, },
{ BFD_RELOC_X86_64_JUMP_SLOT, R_X86_64_JUMP_SLOT, },
{ BFD_RELOC_X86_64_RELATIVE, R_X86_64_RELATIVE, },
{ BFD_RELOC_X86_64_GOTPCREL, R_X86_64_GOTPCREL, },
{ BFD_RELOC_32, R_X86_64_32, },
{ BFD_RELOC_X86_64_32S, R_X86_64_32S, },
{ BFD_RELOC_16, R_X86_64_16, },
{ BFD_RELOC_16_PCREL, R_X86_64_PC16, },
{ BFD_RELOC_8, R_X86_64_8, },
{ BFD_RELOC_8_PCREL, R_X86_64_PC8, },
{ BFD_RELOC_VTABLE_INHERIT, R_X86_64_GNU_VTINHERIT, },
{ BFD_RELOC_VTABLE_ENTRY, R_X86_64_GNU_VTENTRY, },
};
static reloc_howto_type *elf64_x86_64_reloc_type_lookup
PARAMS ((bfd *, bfd_reloc_code_real_type));
static void elf64_x86_64_info_to_howto
PARAMS ((bfd *, arelent *, Elf64_Internal_Rela *));
static struct bfd_link_hash_table *elf64_x86_64_link_hash_table_create
PARAMS ((bfd *));
static boolean elf64_x86_64_elf_object_p PARAMS ((bfd *abfd));
static boolean elf64_x86_64_check_relocs
PARAMS ((bfd *, struct bfd_link_info *, asection *sec,
const Elf_Internal_Rela *));
static asection *elf64_x86_64_gc_mark_hook
PARAMS ((bfd *, struct bfd_link_info *, Elf_Internal_Rela *,
struct elf_link_hash_entry *, Elf_Internal_Sym *));
static boolean elf64_x86_64_gc_sweep_hook
PARAMS ((bfd *, struct bfd_link_info *, asection *,
const Elf_Internal_Rela *));
static struct bfd_hash_entry *elf64_x86_64_link_hash_newfunc
PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
static boolean elf64_x86_64_adjust_dynamic_symbol
PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *));
static boolean elf64_x86_64_size_dynamic_sections
PARAMS ((bfd *, struct bfd_link_info *));
static boolean elf64_x86_64_relocate_section
PARAMS ((bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
Elf_Internal_Rela *, Elf_Internal_Sym *, asection **));
static boolean elf64_x86_64_finish_dynamic_symbol
PARAMS ((bfd *, struct bfd_link_info *, struct elf_link_hash_entry *,
Elf_Internal_Sym *sym));
static boolean elf64_x86_64_finish_dynamic_sections
PARAMS ((bfd *, struct bfd_link_info *));
static enum elf_reloc_type_class elf64_x86_64_reloc_type_class
PARAMS ((const Elf_Internal_Rela *));
/* Given a BFD reloc type, return a HOWTO structure. */
static reloc_howto_type *
elf64_x86_64_reloc_type_lookup (abfd, code)
bfd *abfd ATTRIBUTE_UNUSED;
bfd_reloc_code_real_type code;
{
unsigned int i;
for (i = 0; i < sizeof (x86_64_reloc_map) / sizeof (struct elf_reloc_map);
i++)
{
if (x86_64_reloc_map[i].bfd_reloc_val == code)
return &x86_64_elf_howto_table[i];
}
return 0;
}
/* Given an x86_64 ELF reloc type, fill in an arelent structure. */
static void
elf64_x86_64_info_to_howto (abfd, cache_ptr, dst)
bfd *abfd ATTRIBUTE_UNUSED;
arelent *cache_ptr;
Elf64_Internal_Rela *dst;
{
unsigned r_type, i;
r_type = ELF64_R_TYPE (dst->r_info);
if (r_type < (unsigned int) R_X86_64_GNU_VTINHERIT)
{
BFD_ASSERT (r_type <= (unsigned int) R_X86_64_PC8);
i = r_type;
}
else
{
BFD_ASSERT (r_type < (unsigned int) R_X86_64_max);
i = r_type - ((unsigned int) R_X86_64_GNU_VTINHERIT - R_X86_64_PC8 - 1);
}
cache_ptr->howto = &x86_64_elf_howto_table[i];
BFD_ASSERT (r_type == cache_ptr->howto->type);
}
/* Functions for the x86-64 ELF linker. */
/* The name of the dynamic interpreter. This is put in the .interp
section. */
#define ELF_DYNAMIC_INTERPRETER "/lib/ld64.so.1"
/* The size in bytes of an entry in the global offset table. */
#define GOT_ENTRY_SIZE 8
/* The size in bytes of an entry in the procedure linkage table. */
#define PLT_ENTRY_SIZE 16
/* The first entry in a procedure linkage table looks like this. See the
SVR4 ABI i386 supplement and the x86-64 ABI to see how this works. */
static const bfd_byte elf64_x86_64_plt0_entry[PLT_ENTRY_SIZE] =
{
0xff, 0x35, 8, 0, 0, 0, /* pushq GOT+8(%rip) */
0xff, 0x25, 16, 0, 0, 0, /* jmpq *GOT+16(%rip) */
0x90, 0x90, 0x90, 0x90 /* pad out to 16 bytes with nops. */
};
/* Subsequent entries in a procedure linkage table look like this. */
static const bfd_byte elf64_x86_64_plt_entry[PLT_ENTRY_SIZE] =
{
0xff, 0x25, /* jmpq *name@GOTPC(%rip) */
0, 0, 0, 0, /* replaced with offset to this symbol in .got. */
0x68, /* pushq immediate */
0, 0, 0, 0, /* replaced with index into relocation table. */
0xe9, /* jmp relative */
0, 0, 0, 0 /* replaced with offset to start of .plt0. */
};
/* The x86-64 linker needs to keep track of the number of relocs that
it decides to copy in check_relocs for each symbol. This is so
that it can discard PC relative relocs if it doesn't need them when
linking with -Bsymbolic. We store the information in a field
extending the regular ELF linker hash table. */
/* This structure keeps track of the number of PC relative relocs we
have copied for a given symbol. */
struct elf64_x86_64_pcrel_relocs_copied
{
/* Next section. */
struct elf64_x86_64_pcrel_relocs_copied *next;
/* A section in dynobj. */
asection *section;
/* Number of relocs copied in this section. */
bfd_size_type count;
};
/* x86-64 ELF linker hash entry. */
struct elf64_x86_64_link_hash_entry
{
struct elf_link_hash_entry root;
/* Number of PC relative relocs copied for this symbol. */
struct elf64_x86_64_pcrel_relocs_copied *pcrel_relocs_copied;
};
/* x86-64 ELF linker hash table. */
struct elf64_x86_64_link_hash_table
{
struct elf_link_hash_table root;
};
/* Declare this now that the above structures are defined. */
static boolean elf64_x86_64_discard_copies
PARAMS ((struct elf64_x86_64_link_hash_entry *, PTR));
/* Traverse an x86-64 ELF linker hash table. */
#define elf64_x86_64_link_hash_traverse(table, func, info) \
(elf_link_hash_traverse \
(&(table)->root, \
(boolean (*) PARAMS ((struct elf_link_hash_entry *, PTR))) (func), \
(info)))
/* Get the x86-64 ELF linker hash table from a link_info structure. */
#define elf64_x86_64_hash_table(p) \
((struct elf64_x86_64_link_hash_table *) ((p)->hash))
/* Create an entry in an x86-64 ELF linker hash table. */
static struct bfd_hash_entry *
elf64_x86_64_link_hash_newfunc (entry, table, string)
struct bfd_hash_entry *entry;
struct bfd_hash_table *table;
const char *string;
{
struct elf64_x86_64_link_hash_entry *ret =
(struct elf64_x86_64_link_hash_entry *) entry;
/* Allocate the structure if it has not already been allocated by a
subclass. */
if (ret == (struct elf64_x86_64_link_hash_entry *) NULL)
ret = ((struct elf64_x86_64_link_hash_entry *)
bfd_hash_allocate (table,
sizeof (struct elf64_x86_64_link_hash_entry)));
if (ret == (struct elf64_x86_64_link_hash_entry *) NULL)
return (struct bfd_hash_entry *) ret;
/* Call the allocation method of the superclass. */
ret = ((struct elf64_x86_64_link_hash_entry *)
_bfd_elf_link_hash_newfunc ((struct bfd_hash_entry *) ret,
table, string));
if (ret != (struct elf64_x86_64_link_hash_entry *) NULL)
{
ret->pcrel_relocs_copied = NULL;
}
return (struct bfd_hash_entry *) ret;
}
/* Create an X86-64 ELF linker hash table. */
static struct bfd_link_hash_table *
elf64_x86_64_link_hash_table_create (abfd)
bfd *abfd;
{
struct elf64_x86_64_link_hash_table *ret;
bfd_size_type amt = sizeof (struct elf64_x86_64_link_hash_table);
ret = ((struct elf64_x86_64_link_hash_table *) bfd_alloc (abfd, amt));
if (ret == (struct elf64_x86_64_link_hash_table *) NULL)
return NULL;
if (! _bfd_elf_link_hash_table_init (&ret->root, abfd,
elf64_x86_64_link_hash_newfunc))
{
bfd_release (abfd, ret);
return NULL;
}
return &ret->root.root;
}
static boolean
elf64_x86_64_elf_object_p (abfd)
bfd *abfd;
{
/* Set the right machine number for an x86-64 elf64 file. */
bfd_default_set_arch_mach (abfd, bfd_arch_i386, bfd_mach_x86_64);
return true;
}
/* Look through the relocs for a section during the first phase, and
allocate space in the global offset table or procedure linkage
table. */
static boolean
elf64_x86_64_check_relocs (abfd, info, sec, relocs)
bfd *abfd;
struct bfd_link_info *info;
asection *sec;
const Elf_Internal_Rela *relocs;
{
bfd *dynobj;
Elf_Internal_Shdr *symtab_hdr;
struct elf_link_hash_entry **sym_hashes;
bfd_signed_vma *local_got_refcounts;
const Elf_Internal_Rela *rel;
const Elf_Internal_Rela *rel_end;
asection *sgot;
asection *srelgot;
asection *sreloc;
if (info->relocateable)
return true;
dynobj = elf_hash_table (info)->dynobj;
symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
sym_hashes = elf_sym_hashes (abfd);
local_got_refcounts = elf_local_got_refcounts (abfd);
sgot = srelgot = sreloc = NULL;
rel_end = relocs + sec->reloc_count;
for (rel = relocs; rel < rel_end; rel++)
{
unsigned long r_symndx;
struct elf_link_hash_entry *h;
r_symndx = ELF64_R_SYM (rel->r_info);
if (r_symndx < symtab_hdr->sh_info)
h = NULL;
else
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
/* Some relocs require a global offset table. */
if (dynobj == NULL)
{
switch (ELF64_R_TYPE (rel->r_info))
{
case R_X86_64_GOT32:
case R_X86_64_GOTPCREL:
elf_hash_table (info)->dynobj = dynobj = abfd;
if (! _bfd_elf_create_got_section (dynobj, info))
return false;
break;
}
}
switch (ELF64_R_TYPE (rel->r_info))
{
case R_X86_64_GOTPCREL:
case R_X86_64_GOT32:
/* This symbol requires a global offset table entry. */
if (sgot == NULL)
{
sgot = bfd_get_section_by_name (dynobj, ".got");
BFD_ASSERT (sgot != NULL);
}
if (srelgot == NULL && (h != NULL || info->shared))
{
srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
if (srelgot == NULL)
{
srelgot = bfd_make_section (dynobj, ".rela.got");
if (srelgot == NULL
|| ! bfd_set_section_flags (dynobj, srelgot,
(SEC_ALLOC
| SEC_LOAD
| SEC_HAS_CONTENTS
| SEC_IN_MEMORY
| SEC_LINKER_CREATED
| SEC_READONLY))
|| ! bfd_set_section_alignment (dynobj, srelgot, 3))
return false;
}
}
if (h != NULL)
{
if (h->got.refcount == 0)
{
/* Make sure this symbol is output as a dynamic symbol. */
if (h->dynindx == -1)
{
if (! bfd_elf64_link_record_dynamic_symbol (info, h))
return false;
}
sgot->_raw_size += GOT_ENTRY_SIZE;
srelgot->_raw_size += sizeof (Elf64_External_Rela);
}
h->got.refcount += 1;
}
else
{
/* This is a global offset table entry for a local symbol. */
if (local_got_refcounts == NULL)
{
bfd_size_type size;
size = symtab_hdr->sh_info;
size *= sizeof (bfd_signed_vma);
local_got_refcounts = ((bfd_signed_vma *)
bfd_zalloc (abfd, size));
if (local_got_refcounts == NULL)
return false;
elf_local_got_refcounts (abfd) = local_got_refcounts;
}
if (local_got_refcounts[r_symndx] == 0)
{
sgot->_raw_size += GOT_ENTRY_SIZE;
if (info->shared)
{
/* If we are generating a shared object, we need to
output a R_X86_64_RELATIVE reloc so that the dynamic
linker can adjust this GOT entry. */
srelgot->_raw_size += sizeof (Elf64_External_Rela);
}
}
local_got_refcounts[r_symndx] += 1;
}
break;
case R_X86_64_PLT32:
/* This symbol requires a procedure linkage table entry. We
actually build the entry in adjust_dynamic_symbol,
because this might be a case of linking PIC code which is
never referenced by a dynamic object, in which case we
don't need to generate a procedure linkage table entry
after all. */
/* If this is a local symbol, we resolve it directly without
creating a procedure linkage table entry. */
if (h == NULL)
continue;
h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
h->plt.refcount += 1;
break;
case R_X86_64_8:
case R_X86_64_16:
case R_X86_64_32:
case R_X86_64_64:
case R_X86_64_32S:
case R_X86_64_PC32:
if (h != NULL)
h->elf_link_hash_flags |= ELF_LINK_NON_GOT_REF;
/* If we are creating a shared library, and this is a reloc
against a global symbol, or a non PC relative reloc
against a local symbol, then we need to copy the reloc
into the shared library. However, if we are linking with
-Bsymbolic, we do not need to copy a reloc against a
global symbol which is defined in an object we are
including in the link (i.e., DEF_REGULAR is set). At
this point we have not seen all the input files, so it is
possible that DEF_REGULAR is not set now but will be set
later (it is never cleared). We account for that
possibility below by storing information in the
pcrel_relocs_copied field of the hash table entry.
A similar situation occurs when creating shared libraries
and symbol visibility changes render the symbol local. */
if (info->shared
&& (sec->flags & SEC_ALLOC) != 0
&& (((ELF64_R_TYPE (rel->r_info) != R_X86_64_PC8)
&& (ELF64_R_TYPE (rel->r_info) != R_X86_64_PC16)
&& (ELF64_R_TYPE (rel->r_info) != R_X86_64_PC32))
|| (h != NULL
&& (! info->symbolic
|| (h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_REGULAR) == 0))))
{
/* When creating a shared object, we must copy these
reloc types into the output file. We create a reloc
section in dynobj and make room for this reloc. */
if (sreloc == NULL)
{
const char *name;
name = (bfd_elf_string_from_elf_section
(abfd,
elf_elfheader (abfd)->e_shstrndx,
elf_section_data (sec)->rel_hdr.sh_name));
if (name == NULL)
return false;
BFD_ASSERT (strncmp (name, ".rela", 5) == 0
&& strcmp (bfd_get_section_name (abfd, sec),
name + 5) == 0);
sreloc = bfd_get_section_by_name (dynobj, name);
if (sreloc == NULL)
{
flagword flags;
sreloc = bfd_make_section (dynobj, name);
flags = (SEC_HAS_CONTENTS | SEC_READONLY
| SEC_IN_MEMORY | SEC_LINKER_CREATED);
if ((sec->flags & SEC_ALLOC) != 0)
flags |= SEC_ALLOC | SEC_LOAD;
if (sreloc == NULL
|| ! bfd_set_section_flags (dynobj, sreloc, flags)
|| ! bfd_set_section_alignment (dynobj, sreloc, 3))
return false;
}
if (sec->flags & SEC_READONLY)
info->flags |= DF_TEXTREL;
}
sreloc->_raw_size += sizeof (Elf64_External_Rela);
/* If this is a global symbol, we count the number of PC
relative relocations we have entered for this symbol,
so that we can discard them later as necessary. Note
that this function is only called if we are using an
elf64_x86_64 linker hash table, which means that h is
really a pointer to an elf64_x86_64_link_hash_entry. */
if (h != NULL
&& ((ELF64_R_TYPE (rel->r_info) == R_X86_64_PC8)
|| (ELF64_R_TYPE (rel->r_info) == R_X86_64_PC16)
|| (ELF64_R_TYPE (rel->r_info) == R_X86_64_PC32)))
{
struct elf64_x86_64_link_hash_entry *eh;
struct elf64_x86_64_pcrel_relocs_copied *p;
eh = (struct elf64_x86_64_link_hash_entry *) h;
for (p = eh->pcrel_relocs_copied; p != NULL; p = p->next)
if (p->section == sreloc)
break;
if (p == NULL)
{
p = ((struct elf64_x86_64_pcrel_relocs_copied *)
bfd_alloc (dynobj, (bfd_size_type) sizeof *p));
if (p == NULL)
return false;
p->next = eh->pcrel_relocs_copied;
eh->pcrel_relocs_copied = p;
p->section = sreloc;
p->count = 0;
}
++p->count;
}
}
break;
/* This relocation describes the C++ object vtable hierarchy.
Reconstruct it for later use during GC. */
case R_X86_64_GNU_VTINHERIT:
if (!_bfd_elf64_gc_record_vtinherit (abfd, sec, h, rel->r_offset))
return false;
break;
/* This relocation describes which C++ vtable entries are actually
used. Record for later use during GC. */
case R_X86_64_GNU_VTENTRY:
if (!_bfd_elf64_gc_record_vtentry (abfd, sec, h, rel->r_addend))
return false;
break;
}
}
return true;
}
/* Return the section that should be marked against GC for a given
relocation. */
static asection *
elf64_x86_64_gc_mark_hook (abfd, info, rel, h, sym)
bfd *abfd;
struct bfd_link_info *info ATTRIBUTE_UNUSED;
Elf_Internal_Rela *rel ATTRIBUTE_UNUSED;
struct elf_link_hash_entry *h;
Elf_Internal_Sym *sym;
{
if (h != NULL)
{
switch (ELF64_R_TYPE (rel->r_info))
{
case R_X86_64_GNU_VTINHERIT:
case R_X86_64_GNU_VTENTRY:
break;
default:
switch (h->root.type)
{
case bfd_link_hash_defined:
case bfd_link_hash_defweak:
return h->root.u.def.section;
case bfd_link_hash_common:
return h->root.u.c.p->section;
default:
break;
}
}
}
else
{
return bfd_section_from_elf_index (abfd, sym->st_shndx);
}
return NULL;
}
/* Update the got entry reference counts for the section being removed. */
static boolean
elf64_x86_64_gc_sweep_hook (abfd, info, sec, relocs)
bfd *abfd;
struct bfd_link_info *info ATTRIBUTE_UNUSED;
asection *sec;
const Elf_Internal_Rela *relocs;
{
Elf_Internal_Shdr *symtab_hdr;
struct elf_link_hash_entry **sym_hashes;
bfd_signed_vma *local_got_refcounts;
const Elf_Internal_Rela *rel, *relend;
unsigned long r_symndx;
struct elf_link_hash_entry *h;
bfd *dynobj;
asection *sgot;
asection *srelgot;
symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
sym_hashes = elf_sym_hashes (abfd);
local_got_refcounts = elf_local_got_refcounts (abfd);
dynobj = elf_hash_table (info)->dynobj;
if (dynobj == NULL)
return true;
sgot = bfd_get_section_by_name (dynobj, ".got");
srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
relend = relocs + sec->reloc_count;
for (rel = relocs; rel < relend; rel++)
switch (ELF64_R_TYPE (rel->r_info))
{
case R_X86_64_GOT32:
case R_X86_64_GOTPCREL:
r_symndx = ELF64_R_SYM (rel->r_info);
if (r_symndx >= symtab_hdr->sh_info)
{
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
if (h->got.refcount > 0)
{
h->got.refcount -= 1;
if (h->got.refcount == 0)
{
sgot->_raw_size -= GOT_ENTRY_SIZE;
srelgot->_raw_size -= sizeof (Elf64_External_Rela);
}
}
}
else if (local_got_refcounts != NULL)
{
if (local_got_refcounts[r_symndx] > 0)
{
local_got_refcounts[r_symndx] -= 1;
if (local_got_refcounts[r_symndx] == 0)
{
sgot->_raw_size -= GOT_ENTRY_SIZE;
if (info->shared)
srelgot->_raw_size -= sizeof (Elf64_External_Rela);
}
}
}
break;
case R_X86_64_PLT32:
r_symndx = ELF64_R_SYM (rel->r_info);
if (r_symndx >= symtab_hdr->sh_info)
{
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
if (h->plt.refcount > 0)
h->plt.refcount -= 1;
}
break;
default:
break;
}
return true;
}
/* Adjust a symbol defined by a dynamic object and referenced by a
regular object. The current definition is in some section of the
dynamic object, but we're not including those sections. We have to
change the definition to something the rest of the link can
understand. */
static boolean
elf64_x86_64_adjust_dynamic_symbol (info, h)
struct bfd_link_info *info;
struct elf_link_hash_entry *h;
{
bfd *dynobj;
asection *s;
unsigned int power_of_two;
dynobj = elf_hash_table (info)->dynobj;
/* Make sure we know what is going on here. */
BFD_ASSERT (dynobj != NULL
&& ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT)
|| h->weakdef != NULL
|| ((h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_DYNAMIC) != 0
&& (h->elf_link_hash_flags
& ELF_LINK_HASH_REF_REGULAR) != 0
&& (h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_REGULAR) == 0)));
/* If this is a function, put it in the procedure linkage table. We
will fill in the contents of the procedure linkage table later,
when we know the address of the .got section. */
if (h->type == STT_FUNC
|| (h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) != 0)
{
if ((! info->shared
&& (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) == 0
&& (h->elf_link_hash_flags & ELF_LINK_HASH_REF_DYNAMIC) == 0)
|| (info->shared && h->plt.refcount <= 0))
{
/* This case can occur if we saw a PLT32 reloc in an input
file, but the symbol was never referred to by a dynamic
object, or if all references were garbage collected. In
such a case, we don't actually need to build a procedure
linkage table, and we can just do a PC32 reloc instead. */
h->plt.offset = (bfd_vma) -1;
h->elf_link_hash_flags &= ~ELF_LINK_HASH_NEEDS_PLT;
return true;
}
/* Make sure this symbol is output as a dynamic symbol. */
if (h->dynindx == -1)
{
if (! bfd_elf64_link_record_dynamic_symbol (info, h))
return false;
}
s = bfd_get_section_by_name (dynobj, ".plt");
BFD_ASSERT (s != NULL);
/* If this is the first .plt entry, make room for the special
first entry. */
if (s->_raw_size == 0)
s->_raw_size = PLT_ENTRY_SIZE;
/* If this symbol is not defined in a regular file, and we are
not generating a shared library, then set the symbol to this
location in the .plt. This is required to make function
pointers compare as equal between the normal executable and
the shared library. */
if (! info->shared
&& (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0)
{
h->root.u.def.section = s;
h->root.u.def.value = s->_raw_size;
}
h->plt.offset = s->_raw_size;
/* Make room for this entry. */
s->_raw_size += PLT_ENTRY_SIZE;
/* We also need to make an entry in the .got.plt section, which
will be placed in the .got section by the linker script. */
s = bfd_get_section_by_name (dynobj, ".got.plt");
BFD_ASSERT (s != NULL);
s->_raw_size += GOT_ENTRY_SIZE;
/* We also need to make an entry in the .rela.plt section. */
s = bfd_get_section_by_name (dynobj, ".rela.plt");
BFD_ASSERT (s != NULL);
s->_raw_size += sizeof (Elf64_External_Rela);
return true;
}
else
h->plt.offset = (bfd_vma) -1;
/* If this is a weak symbol, and there is a real definition, the
processor independent code will have arranged for us to see the
real definition first, and we can just use the same value. */
if (h->weakdef != NULL)
{
BFD_ASSERT (h->weakdef->root.type == bfd_link_hash_defined
|| h->weakdef->root.type == bfd_link_hash_defweak);
h->root.u.def.section = h->weakdef->root.u.def.section;
h->root.u.def.value = h->weakdef->root.u.def.value;
return true;
}
/* This is a reference to a symbol defined by a dynamic object which
is not a function. */
/* If we are creating a shared library, we must presume that the
only references to the symbol are via the global offset table.
For such cases we need not do anything here; the relocations will
be handled correctly by relocate_section. */
if (info->shared)
return true;
/* If there are no references to this symbol that do not use the
GOT, we don't need to generate a copy reloc. */
if ((h->elf_link_hash_flags & ELF_LINK_NON_GOT_REF) == 0)
return true;
/* We must allocate the symbol in our .dynbss section, which will
become part of the .bss section of the executable. There will be
an entry for this symbol in the .dynsym section. The dynamic
object will contain position independent code, so all references
from the dynamic object to this symbol will go through the global
offset table. The dynamic linker will use the .dynsym entry to
determine the address it must put in the global offset table, so
both the dynamic object and the regular object will refer to the
same memory location for the variable. */
s = bfd_get_section_by_name (dynobj, ".dynbss");
BFD_ASSERT (s != NULL);
/* We must generate a R_X86_64_COPY reloc to tell the dynamic linker
to copy the initial value out of the dynamic object and into the
runtime process image. We need to remember the offset into the
.rela.bss section we are going to use. */
if ((h->root.u.def.section->flags & SEC_ALLOC) != 0)
{
asection *srel;
srel = bfd_get_section_by_name (dynobj, ".rela.bss");
BFD_ASSERT (srel != NULL);
srel->_raw_size += sizeof (Elf64_External_Rela);
h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_COPY;
}
/* We need to figure out the alignment required for this symbol. I
have no idea how ELF linkers handle this. 16-bytes is the size
of the largest type that requires hard alignment -- long double. */
/* FIXME: This is VERY ugly. Should be fixed for all architectures using
this construct. */
power_of_two = bfd_log2 (h->size);
if (power_of_two > 4)
power_of_two = 4;
/* Apply the required alignment. */
s->_raw_size = BFD_ALIGN (s->_raw_size, (bfd_size_type) (1 << power_of_two));
if (power_of_two > bfd_get_section_alignment (dynobj, s))
{
if (! bfd_set_section_alignment (dynobj, s, power_of_two))
return false;
}
/* Define the symbol as being at this point in the section. */
h->root.u.def.section = s;
h->root.u.def.value = s->_raw_size;
/* Increment the section size to make room for the symbol. */
s->_raw_size += h->size;
return true;
}
/* Set the sizes of the dynamic sections. */
static boolean
elf64_x86_64_size_dynamic_sections (output_bfd, info)
bfd *output_bfd ATTRIBUTE_UNUSED;
struct bfd_link_info *info;
{
bfd *dynobj;
asection *s;
boolean plt;
boolean relocs;
dynobj = elf_hash_table (info)->dynobj;
BFD_ASSERT (dynobj != NULL);
if (elf_hash_table (info)->dynamic_sections_created)
{
/* Set the contents of the .interp section to the interpreter. */
if (! info->shared)
{
s = bfd_get_section_by_name (dynobj, ".interp");
BFD_ASSERT (s != NULL);
s->_raw_size = sizeof ELF_DYNAMIC_INTERPRETER;
s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
}
}
else
{
/* We may have created entries in the .rela.got section.
However, if we are not creating the dynamic sections, we will
not actually use these entries. Reset the size of .rela.got,
which will cause it to get stripped from the output file
below. */
s = bfd_get_section_by_name (dynobj, ".rela.got");
if (s != NULL)
s->_raw_size = 0;
}
/* If this is a -Bsymbolic shared link, then we need to discard all
PC relative relocs against symbols defined in a regular object.
We allocated space for them in the check_relocs routine, but we
will not fill them in in the relocate_section routine. */
if (info->shared)
elf64_x86_64_link_hash_traverse (elf64_x86_64_hash_table (info),
elf64_x86_64_discard_copies,
(PTR) info);
/* The check_relocs and adjust_dynamic_symbol entry points have
determined the sizes of the various dynamic sections. Allocate
memory for them. */
plt = relocs = false;
for (s = dynobj->sections; s != NULL; s = s->next)
{
const char *name;
boolean strip;
if ((s->flags & SEC_LINKER_CREATED) == 0)
continue;
/* It's OK to base decisions on the section name, because none
of the dynobj section names depend upon the input files. */
name = bfd_get_section_name (dynobj, s);
strip = false;
if (strcmp (name, ".plt") == 0)
{
if (s->_raw_size == 0)
{
/* Strip this section if we don't need it; see the
comment below. */
strip = true;
}
else
{
/* Remember whether there is a PLT. */
plt = true;
}
}
else if (strncmp (name, ".rela", 5) == 0)
{
if (s->_raw_size == 0)
{
/* If we don't need this section, strip it from the
output file. This is mostly to handle .rela.bss and
.rela.plt. We must create both sections in
create_dynamic_sections, because they must be created
before the linker maps input sections to output
sections. The linker does that before
adjust_dynamic_symbol is called, and it is that
function which decides whether anything needs to go
into these sections. */
strip = true;
}
else
{
if (strcmp (name, ".rela.plt") != 0)
relocs = true;
/* We use the reloc_count field as a counter if we need
to copy relocs into the output file. */
s->reloc_count = 0;
}
}
else if (strncmp (name, ".got", 4) != 0)
{
/* It's not one of our sections, so don't allocate space. */
continue;
}
if (strip)
{
_bfd_strip_section_from_output (info, s);
continue;
}
/* Allocate memory for the section contents. We use bfd_zalloc
here in case unused entries are not reclaimed before the
section's contents are written out. This should not happen,
but this way if it does, we get a R_X86_64_NONE reloc instead
of garbage. */
s->contents = (bfd_byte *) bfd_zalloc (dynobj, s->_raw_size);
if (s->contents == NULL && s->_raw_size != 0)
return false;
}
if (elf_hash_table (info)->dynamic_sections_created)
{
/* Add some entries to the .dynamic section. We fill in the
values later, in elf64_x86_64_finish_dynamic_sections, but we
must add the entries now so that we get the correct size for
the .dynamic section. The DT_DEBUG entry is filled in by the
dynamic linker and used by the debugger. */
#define add_dynamic_entry(TAG, VAL) \
bfd_elf64_add_dynamic_entry (info, (bfd_vma) (TAG), (bfd_vma) (VAL))
if (! info->shared)
{
if (!add_dynamic_entry (DT_DEBUG, 0))
return false;
}
if (plt)
{
if (!add_dynamic_entry (DT_PLTGOT, 0)
|| !add_dynamic_entry (DT_PLTRELSZ, 0)
|| !add_dynamic_entry (DT_PLTREL, DT_RELA)
|| !add_dynamic_entry (DT_JMPREL, 0))
return false;
}
if (relocs)
{
if (!add_dynamic_entry (DT_RELA, 0)
|| !add_dynamic_entry (DT_RELASZ, 0)
|| !add_dynamic_entry (DT_RELAENT, sizeof (Elf64_External_Rela)))
return false;
}
if ((info->flags & DF_TEXTREL) != 0)
{
if (!add_dynamic_entry (DT_TEXTREL, 0))
return false;
}
}
#undef add_dynamic_entry
return true;
}
/* This function is called via elf64_x86_64_link_hash_traverse if we are
creating a shared object. In the -Bsymbolic case, it discards the
space allocated to copy PC relative relocs against symbols which
are defined in regular objects. For the normal non-symbolic case,
we also discard space for relocs that have become local due to
symbol visibility changes. We allocated space for them in the
check_relocs routine, but we won't fill them in in the
relocate_section routine. */
static boolean
elf64_x86_64_discard_copies (h, inf)
struct elf64_x86_64_link_hash_entry *h;
PTR inf;
{
struct elf64_x86_64_pcrel_relocs_copied *s;
struct bfd_link_info *info = (struct bfd_link_info *) inf;
/* If a symbol has been forced local or we have found a regular
definition for the symbolic link case, then we won't be needing
any relocs. */
if ((h->root.elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) != 0
&& ((h->root.elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) != 0
|| info->symbolic))
{
for (s = h->pcrel_relocs_copied; s != NULL; s = s->next)
s->section->_raw_size -= s->count * sizeof (Elf64_External_Rela);
}
return true;
}
/* Relocate an x86_64 ELF section. */
static boolean
elf64_x86_64_relocate_section (output_bfd, info, input_bfd, input_section,
contents, relocs, local_syms, local_sections)
bfd *output_bfd;
struct bfd_link_info *info;
bfd *input_bfd;
asection *input_section;
bfd_byte *contents;
Elf_Internal_Rela *relocs;
Elf_Internal_Sym *local_syms;
asection **local_sections;
{
bfd *dynobj;
Elf_Internal_Shdr *symtab_hdr;
struct elf_link_hash_entry **sym_hashes;
bfd_vma *local_got_offsets;
asection *sgot;
asection *splt;
asection *sreloc;
Elf_Internal_Rela *rela;
Elf_Internal_Rela *relend;
dynobj = elf_hash_table (info)->dynobj;
symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr;
sym_hashes = elf_sym_hashes (input_bfd);
local_got_offsets = elf_local_got_offsets (input_bfd);
sreloc = splt = sgot = NULL;
if (dynobj != NULL)
{
splt = bfd_get_section_by_name (dynobj, ".plt");
sgot = bfd_get_section_by_name (dynobj, ".got");
}
rela = relocs;
relend = relocs + input_section->reloc_count;
for (; rela < relend; rela++)
{
int r_type;
reloc_howto_type *howto;
unsigned long r_symndx;
struct elf_link_hash_entry *h;
Elf_Internal_Sym *sym;
asection *sec;
bfd_vma relocation;
bfd_reloc_status_type r;
unsigned int indx;
r_type = ELF64_R_TYPE (rela->r_info);
if (r_type == (int) R_X86_64_GNU_VTINHERIT
|| r_type == (int) R_X86_64_GNU_VTENTRY)
continue;
if ((indx = (unsigned) r_type) >= R_X86_64_max)
{
bfd_set_error (bfd_error_bad_value);
return false;
}
howto = x86_64_elf_howto_table + indx;
r_symndx = ELF64_R_SYM (rela->r_info);
if (info->relocateable)
{
/* This is a relocateable link. We don't have to change
anything, unless the reloc is against a section symbol,
in which case we have to adjust according to where the
section symbol winds up in the output section. */
if (r_symndx < symtab_hdr->sh_info)
{
sym = local_syms + r_symndx;
if (ELF_ST_TYPE (sym->st_info) == STT_SECTION)
{
sec = local_sections[r_symndx];
rela->r_addend += sec->output_offset + sym->st_value;
}
}
continue;
}
/* This is a final link. */
h = NULL;
sym = NULL;
sec = NULL;
if (r_symndx < symtab_hdr->sh_info)
{
sym = local_syms + r_symndx;
sec = local_sections[r_symndx];
relocation = _bfd_elf_rela_local_sym (output_bfd, sym, sec, rela);
}
else
{
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
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;
if (h->root.type == bfd_link_hash_defined
|| h->root.type == bfd_link_hash_defweak)
{
sec = h->root.u.def.section;
if ((r_type == R_X86_64_PLT32
&& splt != NULL
&& h->plt.offset != (bfd_vma) -1)
|| ((r_type == R_X86_64_GOT32 || r_type == R_X86_64_GOTPCREL)
&& elf_hash_table (info)->dynamic_sections_created
&& (!info->shared
|| (! info->symbolic && h->dynindx != -1)
|| (h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_REGULAR) == 0))
|| (info->shared
&& ((! info->symbolic && h->dynindx != -1)
|| (h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_REGULAR) == 0)
&& (r_type == R_X86_64_8
|| r_type == R_X86_64_16
|| r_type == R_X86_64_32
|| r_type == R_X86_64_64
|| r_type == R_X86_64_PC8
|| r_type == R_X86_64_PC16
|| r_type == R_X86_64_PC32)
&& ((input_section->flags & SEC_ALLOC) != 0
/* DWARF will emit R_X86_64_32 relocations in its
sections against symbols defined externally
in shared libraries. We can't do anything
with them here. */
|| ((input_section->flags & SEC_DEBUGGING) != 0
&& (h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_DYNAMIC) != 0))))
{
/* In these cases, we don't need the relocation
value. We check specially because in some
obscure cases sec->output_section will be NULL. */
relocation = 0;
}
else if (sec->output_section == NULL)
{
(*_bfd_error_handler)
(_("%s: warning: unresolvable relocation against symbol `%s' from %s section"),
bfd_archive_filename (input_bfd), h->root.root.string,
bfd_get_section_name (input_bfd, input_section));
relocation = 0;
}
else
relocation = (h->root.u.def.value
+ sec->output_section->vma
+ sec->output_offset);
}
else if (h->root.type == bfd_link_hash_undefweak)
relocation = 0;
else if (info->shared
&& (!info->symbolic || info->allow_shlib_undefined)
&& !info->no_undefined
&& ELF_ST_VISIBILITY (h->other) == STV_DEFAULT)
relocation = 0;
else
{
if (! ((*info->callbacks->undefined_symbol)
(info, h->root.root.string, input_bfd,
input_section, rela->r_offset,
(!info->shared || info->no_undefined
|| ELF_ST_VISIBILITY (h->other)))))
return false;
relocation = 0;
}
}
/* When generating a shared object, the relocations handled here are
copied into the output file to be resolved at run time. */
switch (r_type)
{
case R_X86_64_GOT32:
/* Relocation is to the entry for this symbol in the global
offset table. */
case R_X86_64_GOTPCREL:
/* Use global offset table as symbol value. */
BFD_ASSERT (sgot != NULL);
if (h != NULL)
{
bfd_vma off = h->got.offset;
BFD_ASSERT (off != (bfd_vma) -1);
if (! elf_hash_table (info)->dynamic_sections_created
|| (info->shared
&& (info->symbolic || h->dynindx == -1)
&& (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
{
/* This is actually a static link, or it is a -Bsymbolic
link and the symbol is defined locally, or the symbol
was forced to be local because of a version file. We
must initialize this entry in the global offset table.
Since the offset must always be a multiple of 8, we
use the least significant bit to record whether we
have initialized it already.
When doing a dynamic link, we create a .rela.got
relocation entry to initialize the value. This is
done in the finish_dynamic_symbol routine. */
if ((off & 1) != 0)
off &= ~1;
else
{
bfd_put_64 (output_bfd, relocation,
sgot->contents + off);
h->got.offset |= 1;
}
}
if (r_type == R_X86_64_GOTPCREL)
relocation = sgot->output_section->vma + sgot->output_offset + off;
else
relocation = sgot->output_offset + off;
}
else
{
bfd_vma off;
BFD_ASSERT (local_got_offsets != NULL
&& local_got_offsets[r_symndx] != (bfd_vma) -1);
off = local_got_offsets[r_symndx];
/* The offset must always be a multiple of 8. We use
the least significant bit to record whether we have
already generated the necessary reloc. */
if ((off & 1) != 0)
off &= ~1;
else
{
bfd_put_64 (output_bfd, relocation, sgot->contents + off);
if (info->shared)
{
asection *srelgot;
Elf_Internal_Rela outrel;
/* We need to generate a R_X86_64_RELATIVE reloc
for the dynamic linker. */
srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
BFD_ASSERT (srelgot != NULL);
outrel.r_offset = (sgot->output_section->vma
+ sgot->output_offset
+ off);
outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
outrel.r_addend = relocation;
bfd_elf64_swap_reloca_out (output_bfd, &outrel,
(((Elf64_External_Rela *)
srelgot->contents)
+ srelgot->reloc_count));
++srelgot->reloc_count;
}
local_got_offsets[r_symndx] |= 1;
}
if (r_type == R_X86_64_GOTPCREL)
relocation = sgot->output_section->vma + sgot->output_offset + off;
else
relocation = sgot->output_offset + off;
}
break;
case R_X86_64_PLT32:
/* Relocation is to the entry for this symbol in the
procedure linkage table. */
/* Resolve a PLT32 reloc against a local symbol directly,
without using the procedure linkage table. */
if (h == NULL)
break;
if (h->plt.offset == (bfd_vma) -1 || splt == NULL)
{
/* We didn't make a PLT entry for this symbol. This
happens when statically linking PIC code, or when
using -Bsymbolic. */
break;
}
relocation = (splt->output_section->vma
+ splt->output_offset
+ h->plt.offset);
break;
case R_X86_64_PC8:
case R_X86_64_PC16:
case R_X86_64_PC32:
if (h == NULL || h->dynindx == -1
|| (info->symbolic
&& h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR))
break;
/* Fall through. */
case R_X86_64_8:
case R_X86_64_16:
case R_X86_64_32:
case R_X86_64_64:
/* FIXME: The ABI says the linker should make sure the value is
the same when it's zeroextended to 64 bit. */
if (info->shared
&& r_symndx != 0
&& (input_section->flags & SEC_ALLOC) != 0)
{
Elf_Internal_Rela outrel;
boolean skip, relocate;
/* When generating a shared object, these relocations
are copied into the output file to be resolved at run
time. */
if (sreloc == NULL)
{
const char *name;
name = (bfd_elf_string_from_elf_section
(input_bfd,
elf_elfheader (input_bfd)->e_shstrndx,
elf_section_data (input_section)->rel_hdr.sh_name));
if (name == NULL)
return false;
BFD_ASSERT (strncmp (name, ".rela", 5) == 0
&& strcmp (bfd_get_section_name (input_bfd,
input_section),
name + 5) == 0);
sreloc = bfd_get_section_by_name (dynobj, name);
BFD_ASSERT (sreloc != NULL);
}
skip = false;
outrel.r_offset =
_bfd_elf_section_offset (output_bfd, info, input_section,
rela->r_offset);
if (outrel.r_offset == (bfd_vma) -1)
skip = true;
outrel.r_offset += (input_section->output_section->vma
+ input_section->output_offset);
if (skip)
{
memset (&outrel, 0, sizeof outrel);
relocate = false;
}
/* h->dynindx may be -1 if this symbol was marked to
become local. */
else if (h != NULL
&& ((! info->symbolic && h->dynindx != -1)
|| (h->elf_link_hash_flags
& ELF_LINK_HASH_DEF_REGULAR) == 0))
{
BFD_ASSERT (h->dynindx != -1);
relocate = false;
outrel.r_info = ELF64_R_INFO (h->dynindx, r_type);
outrel.r_addend = relocation + rela->r_addend;
}
else
{
if (r_type == R_X86_64_64)
{
relocate = true;
outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
outrel.r_addend = relocation + rela->r_addend;
}
else
{
long sindx;
if (h == NULL)
sec = local_sections[r_symndx];
else
{
BFD_ASSERT (h->root.type == bfd_link_hash_defined
|| (h->root.type
== bfd_link_hash_defweak));
sec = h->root.u.def.section;
}
if (sec != NULL && bfd_is_abs_section (sec))
sindx = 0;
else if (sec == NULL || sec->owner == NULL)
{
bfd_set_error (bfd_error_bad_value);
return false;
}
else
{
asection *osec;
osec = sec->output_section;
sindx = elf_section_data (osec)->dynindx;
BFD_ASSERT (sindx > 0);
}
relocate = false;
outrel.r_info = ELF64_R_INFO (sindx, r_type);
outrel.r_addend = relocation + rela->r_addend;
}
}
bfd_elf64_swap_reloca_out (output_bfd, &outrel,
(((Elf64_External_Rela *)
sreloc->contents)
+ sreloc->reloc_count));
++sreloc->reloc_count;
/* If this reloc is against an external symbol, we do
not want to fiddle with the addend. Otherwise, we
need to include the symbol value so that it becomes
an addend for the dynamic reloc. */
if (! relocate)
continue;
}
break;
default:
break;
}
r = _bfd_final_link_relocate (howto, input_bfd, input_section,
contents, rela->r_offset,
relocation, rela->r_addend);
if (r != bfd_reloc_ok)
{
switch (r)
{
default:
case bfd_reloc_outofrange:
abort ();
case bfd_reloc_overflow:
{
const char *name;
if (h != NULL)
name = h->root.root.string;
else
{
name = bfd_elf_string_from_elf_section (input_bfd,
symtab_hdr->sh_link,
sym->st_name);
if (name == NULL)
return false;
if (*name == '\0')
name = bfd_section_name (input_bfd, sec);
}
if (! ((*info->callbacks->reloc_overflow)
(info, name, howto->name, (bfd_vma) 0,
input_bfd, input_section, rela->r_offset)))
return false;
}
break;
}
}
}
return true;
}
/* Finish up dynamic symbol handling. We set the contents of various
dynamic sections here. */
static boolean
elf64_x86_64_finish_dynamic_symbol (output_bfd, info, h, sym)
bfd *output_bfd;
struct bfd_link_info *info;
struct elf_link_hash_entry *h;
Elf_Internal_Sym *sym;
{
bfd *dynobj;
dynobj = elf_hash_table (info)->dynobj;
if (h->plt.offset != (bfd_vma) -1)
{
asection *splt;
asection *sgot;
asection *srela;
bfd_vma plt_index;
bfd_vma got_offset;
Elf_Internal_Rela rela;
/* This symbol has an entry in the procedure linkage table. Set
it up. */
BFD_ASSERT (h->dynindx != -1);
splt = bfd_get_section_by_name (dynobj, ".plt");
sgot = bfd_get_section_by_name (dynobj, ".got.plt");
srela = bfd_get_section_by_name (dynobj, ".rela.plt");
BFD_ASSERT (splt != NULL && sgot != NULL && srela != NULL);
/* Get the index in the procedure linkage table which
corresponds to this symbol. This is the index of this symbol
in all the symbols for which we are making plt entries. The
first entry in the procedure linkage table is reserved. */
plt_index = h->plt.offset / PLT_ENTRY_SIZE - 1;
/* Get the offset into the .got table of the entry that
corresponds to this function. Each .got entry is GOT_ENTRY_SIZE
bytes. The first three are reserved for the dynamic linker. */
got_offset = (plt_index + 3) * GOT_ENTRY_SIZE;
/* Fill in the entry in the procedure linkage table. */
memcpy (splt->contents + h->plt.offset, elf64_x86_64_plt_entry,
PLT_ENTRY_SIZE);
/* Insert the relocation positions of the plt section. The magic
numbers at the end of the statements are the positions of the
relocations in the plt section. */
/* Put offset for jmp *name@GOTPCREL(%rip), since the
instruction uses 6 bytes, subtract this value. */
bfd_put_32 (output_bfd,
(sgot->output_section->vma
+ sgot->output_offset
+ got_offset
- splt->output_section->vma
- splt->output_offset
- h->plt.offset
- 6),
splt->contents + h->plt.offset + 2);
/* Put relocation index. */
bfd_put_32 (output_bfd, plt_index,
splt->contents + h->plt.offset + 7);
/* Put offset for jmp .PLT0. */
bfd_put_32 (output_bfd, - (h->plt.offset + PLT_ENTRY_SIZE),
splt->contents + h->plt.offset + 12);
/* Fill in the entry in the global offset table, initially this
points to the pushq instruction in the PLT which is at offset 6. */
bfd_put_64 (output_bfd, (splt->output_section->vma + splt->output_offset
+ h->plt.offset + 6),
sgot->contents + got_offset);
/* Fill in the entry in the .rela.plt section. */
rela.r_offset = (sgot->output_section->vma
+ sgot->output_offset
+ got_offset);
rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_JUMP_SLOT);
rela.r_addend = 0;
bfd_elf64_swap_reloca_out (output_bfd, &rela,
((Elf64_External_Rela *) srela->contents
+ plt_index));
if ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0)
{
/* Mark the symbol as undefined, rather than as defined in
the .plt section. Leave the value alone. */
sym->st_shndx = SHN_UNDEF;
/* If the symbol is weak, we do need to clear the value.
Otherwise, the PLT entry would provide a definition for
the symbol even if the symbol wasn't defined anywhere,
and so the symbol would never be NULL. */
if ((h->elf_link_hash_flags & ELF_LINK_HASH_REF_REGULAR_NONWEAK)
== 0)
sym->st_value = 0;
}
}
if (h->got.offset != (bfd_vma) -1)
{
asection *sgot;
asection *srela;
Elf_Internal_Rela rela;
/* This symbol has an entry in the global offset table. Set it
up. */
sgot = bfd_get_section_by_name (dynobj, ".got");
srela = bfd_get_section_by_name (dynobj, ".rela.got");
BFD_ASSERT (sgot != NULL && srela != NULL);
rela.r_offset = (sgot->output_section->vma
+ sgot->output_offset
+ (h->got.offset &~ (bfd_vma) 1));
/* If this is a static link, or it is a -Bsymbolic link and the
symbol is defined locally or was forced to be local because
of a version file, we just want to emit a RELATIVE reloc.
The entry in the global offset table will already have been
initialized in the relocate_section function. */
if (! elf_hash_table (info)->dynamic_sections_created
|| (info->shared
&& (info->symbolic || h->dynindx == -1)
&& (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
{
BFD_ASSERT((h->got.offset & 1) != 0);
rela.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
rela.r_addend = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
}
else
{
BFD_ASSERT((h->got.offset & 1) == 0);
bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + h->got.offset);
rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_GLOB_DAT);
rela.r_addend = 0;
}
bfd_elf64_swap_reloca_out (output_bfd, &rela,
((Elf64_External_Rela *) srela->contents
+ srela->reloc_count));
++srela->reloc_count;
}
if ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_COPY) != 0)
{
asection *s;
Elf_Internal_Rela rela;
/* This symbol needs a copy reloc. Set it up. */
BFD_ASSERT (h->dynindx != -1
&& (h->root.type == bfd_link_hash_defined
|| h->root.type == bfd_link_hash_defweak));
s = bfd_get_section_by_name (h->root.u.def.section->owner,
".rela.bss");
BFD_ASSERT (s != NULL);
rela.r_offset = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_COPY);
rela.r_addend = 0;
bfd_elf64_swap_reloca_out (output_bfd, &rela,
((Elf64_External_Rela *) s->contents
+ s->reloc_count));
++s->reloc_count;
}
/* Mark _DYNAMIC and _GLOBAL_OFFSET_TABLE_ as absolute. */
if (strcmp (h->root.root.string, "_DYNAMIC") == 0
|| strcmp (h->root.root.string, "_GLOBAL_OFFSET_TABLE_") == 0)
sym->st_shndx = SHN_ABS;
return true;
}
/* Finish up the dynamic sections. */
static boolean
elf64_x86_64_finish_dynamic_sections (output_bfd, info)
bfd *output_bfd;
struct bfd_link_info *info;
{
bfd *dynobj;
asection *sdyn;
asection *sgot;
dynobj = elf_hash_table (info)->dynobj;
sgot = bfd_get_section_by_name (dynobj, ".got.plt");
BFD_ASSERT (sgot != NULL);
sdyn = bfd_get_section_by_name (dynobj, ".dynamic");
if (elf_hash_table (info)->dynamic_sections_created)
{
asection *splt;
Elf64_External_Dyn *dyncon, *dynconend;
BFD_ASSERT (sdyn != NULL);
dyncon = (Elf64_External_Dyn *) sdyn->contents;
dynconend = (Elf64_External_Dyn *) (sdyn->contents + sdyn->_raw_size);
for (; dyncon < dynconend; dyncon++)
{
Elf_Internal_Dyn dyn;
const char *name;
asection *s;
bfd_elf64_swap_dyn_in (dynobj, dyncon, &dyn);
switch (dyn.d_tag)
{
default:
continue;
case DT_PLTGOT:
name = ".got";
goto get_vma;
case DT_JMPREL:
name = ".rela.plt";
get_vma:
s = bfd_get_section_by_name (output_bfd, name);
BFD_ASSERT (s != NULL);
dyn.d_un.d_ptr = s->vma;
break;
case DT_RELASZ:
/* FIXME: This comment and code is from elf64-alpha.c: */
/* My interpretation of the TIS v1.1 ELF document indicates
that RELASZ should not include JMPREL. This is not what
the rest of the BFD does. It is, however, what the
glibc ld.so wants. Do this fixup here until we found
out who is right. */
s = bfd_get_section_by_name (output_bfd, ".rela.plt");
if (s)
{
/* Subtract JMPREL size from RELASZ. */
dyn.d_un.d_val -=
(s->_cooked_size ? s->_cooked_size : s->_raw_size);
}
break;
case DT_PLTRELSZ:
s = bfd_get_section_by_name (output_bfd, ".rela.plt");
BFD_ASSERT (s != NULL);
dyn.d_un.d_val =
(s->_cooked_size != 0 ? s->_cooked_size : s->_raw_size);
break;
}
bfd_elf64_swap_dyn_out (output_bfd, &dyn, dyncon);
}
/* Initialize the contents of the .plt section. */
splt = bfd_get_section_by_name (dynobj, ".plt");
BFD_ASSERT (splt != NULL);
if (splt->_raw_size > 0)
{
/* Fill in the first entry in the procedure linkage table. */
memcpy (splt->contents, elf64_x86_64_plt0_entry, PLT_ENTRY_SIZE);
/* Add offset for pushq GOT+8(%rip), since the instruction
uses 6 bytes subtract this value. */
bfd_put_32 (output_bfd,
(sgot->output_section->vma
+ sgot->output_offset
+ 8
- splt->output_section->vma
- splt->output_offset
- 6),
splt->contents + 2);
/* Add offset for jmp *GOT+16(%rip). The 12 is the offset to
the end of the instruction. */
bfd_put_32 (output_bfd,
(sgot->output_section->vma
+ sgot->output_offset
+ 16
- splt->output_section->vma
- splt->output_offset
- 12),
splt->contents + 8);
}
elf_section_data (splt->output_section)->this_hdr.sh_entsize =
PLT_ENTRY_SIZE;
}
/* Set the first entry in the global offset table to the address of
the dynamic section. */
if (sgot->_raw_size > 0)
{
if (sdyn == NULL)
bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents);
else
bfd_put_64 (output_bfd,
sdyn->output_section->vma + sdyn->output_offset,
sgot->contents);
/* Write GOT[1] and GOT[2], needed for the dynamic linker. */
bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + GOT_ENTRY_SIZE);
bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + GOT_ENTRY_SIZE*2);
}
elf_section_data (sgot->output_section)->this_hdr.sh_entsize =
GOT_ENTRY_SIZE;
return true;
}
static enum elf_reloc_type_class
elf64_x86_64_reloc_type_class (rela)
const Elf_Internal_Rela *rela;
{
switch ((int) ELF64_R_TYPE (rela->r_info))
{
case R_X86_64_RELATIVE:
return reloc_class_relative;
case R_X86_64_JUMP_SLOT:
return reloc_class_plt;
case R_X86_64_COPY:
return reloc_class_copy;
default:
return reloc_class_normal;
}
}
#define TARGET_LITTLE_SYM bfd_elf64_x86_64_vec
#define TARGET_LITTLE_NAME "elf64-x86-64"
#define ELF_ARCH bfd_arch_i386
#define ELF_MACHINE_CODE EM_X86_64
#define ELF_MAXPAGESIZE 0x100000
#define elf_backend_can_gc_sections 1
#define elf_backend_can_refcount 1
#define elf_backend_want_got_plt 1
#define elf_backend_plt_readonly 1
#define elf_backend_want_plt_sym 0
#define elf_backend_got_header_size (GOT_ENTRY_SIZE*3)
#define elf_backend_plt_header_size PLT_ENTRY_SIZE
#define elf_info_to_howto elf64_x86_64_info_to_howto
#define bfd_elf64_bfd_final_link _bfd_elf64_gc_common_final_link
#define bfd_elf64_bfd_link_hash_table_create \
elf64_x86_64_link_hash_table_create
#define bfd_elf64_bfd_reloc_type_lookup elf64_x86_64_reloc_type_lookup
#define elf_backend_adjust_dynamic_symbol elf64_x86_64_adjust_dynamic_symbol
#define elf_backend_check_relocs elf64_x86_64_check_relocs
#define elf_backend_create_dynamic_sections _bfd_elf_create_dynamic_sections
#define elf_backend_finish_dynamic_sections \
elf64_x86_64_finish_dynamic_sections
#define elf_backend_finish_dynamic_symbol elf64_x86_64_finish_dynamic_symbol
#define elf_backend_gc_mark_hook elf64_x86_64_gc_mark_hook
#define elf_backend_gc_sweep_hook elf64_x86_64_gc_sweep_hook
#define elf_backend_relocate_section elf64_x86_64_relocate_section
#define elf_backend_size_dynamic_sections elf64_x86_64_size_dynamic_sections
#define elf_backend_object_p elf64_x86_64_elf_object_p
#define elf_backend_reloc_type_class elf64_x86_64_reloc_type_class
#include "elf64-target.h"
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