mirror/binutils-gdb
2
0
Fork 0
mirror of https://sourceware.org/git/binutils-gdb.git synced 2025-02-17 13:10:12 +08:00
Code Issues Packages Projects Releases Wiki Activity
5cb0993caf
binutils-gdb/bfd/elf32-i386.c
Ken Raeburn ede4eed483 Added new files elflink.c, elflink.h, elfcore.h. 
Moved some mostly size-independent stuff from elfcode.h to elf.c, adding a data
structure to elfcode.h with some misc data and callback functions.  Added a
pointer to that structure to the target back end data.  More work can be done
here.

Renamed generic elf routines (not cpu-specific stuff) to start with bfd_elf or
_bfd_elf.  Updated most call sites, sometimes defined some macros.

Moved some dynamic linking support code from m68k, sparc, i386 to common files,
using target back end flags to control behavior.  More work can probably be
done here too.

Moved core- and linker-support code out of elfcode.h to elf.c, elfcore.h,
elflink.h, or elflink.c.  Now elfcode.h contains only .o and executable
support, plus #includes of elfcore.h and elflink.h.  Much of the contents of
these other header files can probably still be moved from the .h files to the
.c files, to get compiled only once.

Cleaned up some "gcc -Wall" warnings regarding unused or uninitialized
variables, in generic and cpu-specific code.
1995-07-06 02:22:00 +00:00

1512 lines
43 KiB
C
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/* Intel 80386/80486-specific support for 32-bit ELF
Copyright 1993, 1994, 1995 Free Software Foundation, Inc.
This file is part of BFD, the Binary File Descriptor library.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 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., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "bfd.h"
#include "sysdep.h"
#include "bfdlink.h"
#include "libbfd.h"
#include "libelf.h"
static reloc_howto_type *elf_i386_reloc_type_lookup
PARAMS ((bfd *, bfd_reloc_code_real_type));
static void elf_i386_info_to_howto
PARAMS ((bfd *, arelent *, Elf32_Internal_Rela *));
static void elf_i386_info_to_howto_rel
PARAMS ((bfd *, arelent *, Elf32_Internal_Rel *));
static boolean elf_i386_check_relocs
PARAMS ((bfd *, struct bfd_link_info *, asection *,
const Elf_Internal_Rela *));
static boolean elf_i386_adjust_dynamic_symbol
PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *));
static boolean elf_i386_size_dynamic_sections
PARAMS ((bfd *, struct bfd_link_info *));
static boolean elf_i386_relocate_section
PARAMS ((bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
Elf_Internal_Rela *, Elf_Internal_Sym *, asection **));
static boolean elf_i386_finish_dynamic_symbol
PARAMS ((bfd *, struct bfd_link_info *, struct elf_link_hash_entry *,
Elf_Internal_Sym *));
static boolean elf_i386_finish_dynamic_sections
PARAMS ((bfd *, struct bfd_link_info *));
#define USE_REL 1 /* 386 uses REL relocations instead of RELA */
enum reloc_type
{
R_386_NONE = 0,
R_386_32,
R_386_PC32,
R_386_GOT32,
R_386_PLT32,
R_386_COPY,
R_386_GLOB_DAT,
R_386_JUMP_SLOT,
R_386_RELATIVE,
R_386_GOTOFF,
R_386_GOTPC,
R_386_max
};
#if 0
static CONST char *CONST reloc_type_names[] =
{
"R_386_NONE",
"R_386_32",
"R_386_PC32",
"R_386_GOT32",
"R_386_PLT32",
"R_386_COPY",
"R_386_GLOB_DAT",
"R_386_JUMP_SLOT",
"R_386_RELATIVE",
"R_386_GOTOFF",
"R_386_GOTPC",
};
#endif
static reloc_howto_type elf_howto_table[]=
{
HOWTO(R_386_NONE, 0,0, 0,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_NONE", true,0x00000000,0x00000000,false),
HOWTO(R_386_32, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_32", true,0xffffffff,0xffffffff,false),
HOWTO(R_386_PC32, 0,2,32,true, 0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_PC32", true,0xffffffff,0xffffffff,true),
HOWTO(R_386_GOT32, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_GOT32", true,0xffffffff,0xffffffff,false),
HOWTO(R_386_PLT32, 0,2,32,true,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_PLT32", true,0xffffffff,0xffffffff,true),
HOWTO(R_386_COPY, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_COPY", true,0xffffffff,0xffffffff,false),
HOWTO(R_386_GLOB_DAT, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_GLOB_DAT", true,0xffffffff,0xffffffff,false),
HOWTO(R_386_JUMP_SLOT, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_JUMP_SLOT",true,0xffffffff,0xffffffff,false),
HOWTO(R_386_RELATIVE, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_RELATIVE", true,0xffffffff,0xffffffff,false),
HOWTO(R_386_GOTOFF, 0,2,32,false,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_GOTOFF", true,0xffffffff,0xffffffff,false),
HOWTO(R_386_GOTPC, 0,2,32,true,0,complain_overflow_bitfield, bfd_elf_generic_reloc,"R_386_GOTPC", true,0xffffffff,0xffffffff,true),
};
#ifdef DEBUG_GEN_RELOC
#define TRACE(str) fprintf (stderr, "i386 bfd reloc lookup %d (%s)\n", code, str)
#else
#define TRACE(str)
#endif
static reloc_howto_type *
elf_i386_reloc_type_lookup (abfd, code)
bfd *abfd;
bfd_reloc_code_real_type code;
{
switch (code)
{
case BFD_RELOC_NONE:
TRACE ("BFD_RELOC_NONE");
return &elf_howto_table[ (int)R_386_NONE ];
case BFD_RELOC_32:
TRACE ("BFD_RELOC_32");
return &elf_howto_table[ (int)R_386_32 ];
case BFD_RELOC_32_PCREL:
TRACE ("BFD_RELOC_PC32");
return &elf_howto_table[ (int)R_386_PC32 ];
case BFD_RELOC_386_GOT32:
TRACE ("BFD_RELOC_386_GOT32");
return &elf_howto_table[ (int)R_386_GOT32 ];
case BFD_RELOC_386_PLT32:
TRACE ("BFD_RELOC_386_PLT32");
return &elf_howto_table[ (int)R_386_PLT32 ];
case BFD_RELOC_386_COPY:
TRACE ("BFD_RELOC_386_COPY");
return &elf_howto_table[ (int)R_386_COPY ];
case BFD_RELOC_386_GLOB_DAT:
TRACE ("BFD_RELOC_386_GLOB_DAT");
return &elf_howto_table[ (int)R_386_GLOB_DAT ];
case BFD_RELOC_386_JUMP_SLOT:
TRACE ("BFD_RELOC_386_JUMP_SLOT");
return &elf_howto_table[ (int)R_386_JUMP_SLOT ];
case BFD_RELOC_386_RELATIVE:
TRACE ("BFD_RELOC_386_RELATIVE");
return &elf_howto_table[ (int)R_386_RELATIVE ];
case BFD_RELOC_386_GOTOFF:
TRACE ("BFD_RELOC_386_GOTOFF");
return &elf_howto_table[ (int)R_386_GOTOFF ];
case BFD_RELOC_386_GOTPC:
TRACE ("BFD_RELOC_386_GOTPC");
return &elf_howto_table[ (int)R_386_GOTPC ];
default:
break;
}
TRACE ("Unknown");
return 0;
}
static void
elf_i386_info_to_howto (abfd, cache_ptr, dst)
bfd *abfd;
arelent *cache_ptr;
Elf32_Internal_Rela *dst;
{
BFD_ASSERT (ELF32_R_TYPE(dst->r_info) < (unsigned int) R_386_max);
cache_ptr->howto = &elf_howto_table[ELF32_R_TYPE(dst->r_info)];
}
static void
elf_i386_info_to_howto_rel (abfd, cache_ptr, dst)
bfd *abfd;
arelent *cache_ptr;
Elf32_Internal_Rel *dst;
{
BFD_ASSERT (ELF32_R_TYPE(dst->r_info) < (unsigned int) R_386_max);
cache_ptr->howto = &elf_howto_table[ELF32_R_TYPE(dst->r_info)];
}
/* Functions for the i386 ELF linker. */
/* The name of the dynamic interpreter. This is put in the .interp
section. */
#define ELF_DYNAMIC_INTERPRETER "/usr/lib/libc.so.1"
/* The size in bytes of an entry in the procedure linkage table. */
#define PLT_ENTRY_SIZE 16
/* The first entry in an absolute procedure linkage table looks like
this. See the SVR4 ABI i386 supplement to see how this works. */
static const bfd_byte elf_i386_plt0_entry[PLT_ENTRY_SIZE] =
{
0xff, 0x35, /* pushl contents of address */
0, 0, 0, 0, /* replaced with address of .got + 4. */
0xff, 0x25, /* jmp indirect */
0, 0, 0, 0, /* replaced with address of .got + 8. */
0, 0, 0, 0 /* pad out to 16 bytes. */
};
/* Subsequent entries in an absolute procedure linkage table look like
this. */
static const bfd_byte elf_i386_plt_entry[PLT_ENTRY_SIZE] =
{
0xff, 0x25, /* jmp indirect */
0, 0, 0, 0, /* replaced with address of this symbol in .got. */
0x68, /* pushl immediate */
0, 0, 0, 0, /* replaced with offset into relocation table. */
0xe9, /* jmp relative */
0, 0, 0, 0 /* replaced with offset to start of .plt. */
};
/* The first entry in a PIC procedure linkage table look like this. */
static const bfd_byte elf_i386_pic_plt0_entry[PLT_ENTRY_SIZE] =
{
0xff, 0xb3, 4, 0, 0, 0, /* pushl 4(%ebx) */
0xff, 0xa3, 8, 0, 0, 0, /* jmp *8(%ebx) */
0, 0, 0, 0 /* pad out to 16 bytes. */
};
/* Subsequent entries in a PIC procedure linkage table look like this. */
static const bfd_byte elf_i386_pic_plt_entry[PLT_ENTRY_SIZE] =
{
0xff, 0xa3, /* jmp *offset(%ebx) */
0, 0, 0, 0, /* replaced with offset of this symbol in .got. */
0x68, /* pushl immediate */
0, 0, 0, 0, /* replaced with offset into relocation table. */
0xe9, /* jmp relative */
0, 0, 0, 0 /* replaced with offset to start of .plt. */
};
/* 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
elf_i386_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_vma *local_got_offsets;
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_offsets = elf_local_got_offsets (abfd);
sgot = NULL;
srelgot = NULL;
sreloc = NULL;
rel_end = relocs + sec->reloc_count;
for (rel = relocs; rel < rel_end; rel++)
{
long r_symndx;
struct elf_link_hash_entry *h;
r_symndx = ELF32_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 (ELF32_R_TYPE (rel->r_info))
{
case R_386_GOT32:
case R_386_GOTOFF:
case R_386_GOTPC:
elf_hash_table (info)->dynobj = dynobj = abfd;
if (! _bfd_elf_create_got_section (dynobj, info))
return false;
break;
default:
break;
}
}
switch (ELF32_R_TYPE (rel->r_info))
{
case R_386_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, ".rel.got");
if (srelgot == NULL)
{
srelgot = bfd_make_section (dynobj, ".rel.got");
if (srelgot == NULL
|| ! bfd_set_section_flags (dynobj, srelgot,
(SEC_ALLOC
| SEC_LOAD
| SEC_HAS_CONTENTS
| SEC_IN_MEMORY
| SEC_READONLY))
|| ! bfd_set_section_alignment (dynobj, srelgot, 2))
return false;
}
}
if (h != NULL)
{
if (h->got_offset != (bfd_vma) -1)
{
/* We have already allocated space in the .got. */
break;
}
h->got_offset = sgot->_raw_size;
/* Make sure this symbol is output as a dynamic symbol. */
if (h->dynindx == -1)
{
if (! bfd_elf32_link_record_dynamic_symbol (info, h))
return false;
}
srelgot->_raw_size += sizeof (Elf32_External_Rel);
}
else
{
/* This is a global offset table entry for a local
symbol. */
if (local_got_offsets == NULL)
{
size_t size;
register int i;
size = symtab_hdr->sh_info * sizeof (bfd_vma);
local_got_offsets = (bfd_vma *) bfd_alloc (abfd, size);
if (local_got_offsets == NULL)
{
bfd_set_error (bfd_error_no_memory);
return false;
}
elf_local_got_offsets (abfd) = local_got_offsets;
for (i = 0; i < symtab_hdr->sh_info; i++)
local_got_offsets[i] = (bfd_vma) -1;
}
if (local_got_offsets[r_symndx] != (bfd_vma) -1)
{
/* We have already allocated space in the .got. */
break;
}
local_got_offsets[r_symndx] = sgot->_raw_size;
if (info->shared)
{
/* If we are generating a shared object, we need to
output a R_386_RELATIVE reloc so that the dynamic
linker can adjust this GOT entry. */
srelgot->_raw_size += sizeof (Elf32_External_Rel);
}
}
sgot->_raw_size += 4;
break;
case R_386_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 without
linking in any dynamic objects, in which case we don't
need to generate a procedure linkage table after all. */
/* If this is a local symbol, we resolve it directly without
creating a procedure linkage table entry. */
if (h == NULL)
continue;
/* Make sure this symbol is output as a dynamic symbol. */
if (h->dynindx == -1)
{
if (! bfd_elf32_link_record_dynamic_symbol (info, h))
return false;
}
h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
break;
case R_386_32:
case R_386_PC32:
if (info->shared
&& (sec->flags & SEC_ALLOC) != 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, ".rel", 4) == 0
&& strcmp (bfd_get_section_name (abfd, sec),
name + 4) == 0);
sreloc = bfd_get_section_by_name (dynobj, name);
if (sreloc == NULL)
{
sreloc = bfd_make_section (dynobj, name);
if (sreloc == NULL
|| ! bfd_set_section_flags (dynobj, sreloc,
(SEC_ALLOC
| SEC_LOAD
| SEC_HAS_CONTENTS
| SEC_IN_MEMORY
| SEC_READONLY))
|| ! bfd_set_section_alignment (dynobj, sreloc, 2))
return false;
}
}
sreloc->_raw_size += sizeof (Elf32_External_Rel);
}
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
elf_i386_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->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 (! elf_hash_table (info)->dynamic_sections_created)
{
/* This case can occur if we saw a PLT32 reloc in an input
file, but none of the input files were dynamic objects.
In such a case, we don't actually need to build a
procedure linkage table, and we can just do a PC32 reloc
instead. */
BFD_ASSERT ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) != 0);
return true;
}
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 += 4;
/* We also need to make an entry in the .rel.plt section. */
s = bfd_get_section_by_name (dynobj, ".rel.plt");
BFD_ASSERT (s != NULL);
s->_raw_size += sizeof (Elf32_External_Rel);
return true;
}
/* 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;
/* 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);
/* If the symbol is currently defined in the .bss section of the
dynamic object, then it is OK to simply initialize it to zero.
If the symbol is in some other section, we must generate a
R_386_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 .rel.bss section
we are going to use. */
if ((h->root.u.def.section->flags & SEC_LOAD) != 0)
{
asection *srel;
srel = bfd_get_section_by_name (dynobj, ".rel.bss");
BFD_ASSERT (srel != NULL);
srel->_raw_size += sizeof (Elf32_External_Rel);
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. */
power_of_two = bfd_log2 (h->size);
if (power_of_two > 3)
power_of_two = 3;
/* 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
elf_i386_size_dynamic_sections (output_bfd, info)
bfd *output_bfd;
struct bfd_link_info *info;
{
bfd *dynobj;
asection *s;
boolean plt;
boolean relocs;
boolean reltext;
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 .rel.got section.
However, if we are not creating the dynamic sections, we will
not actually use these entries. Reset the size of .rel.got,
which will cause it to get stripped from the output file
below. */
s = bfd_get_section_by_name (dynobj, ".rel.got");
if (s != NULL)
s->_raw_size = 0;
}
/* The check_relocs and adjust_dynamic_symbol entry points have
determined the sizes of the various dynamic sections. Allocate
memory for them. */
plt = false;
relocs = false;
reltext = false;
for (s = dynobj->sections; s != NULL; s = s->next)
{
const char *name;
boolean strip;
if ((s->flags & SEC_IN_MEMORY) == 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, ".rel", 4) == 0)
{
if (s->_raw_size == 0)
{
/* If we don't need this section, strip it from the
output file. This is mostly to handle .rel.bss and
.rel.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
{
asection *target;
/* Remember whether there are any reloc sections other
than .rel.plt. */
if (strcmp (name, ".rel.plt") != 0)
relocs = true;
/* If this relocation section applies to a read only
section, then we probably need a DT_TEXTREL entry. */
target = bfd_get_section_by_name (output_bfd, name + 4);
if (target != NULL
&& (target->flags & SEC_READONLY) != 0)
reltext = 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)
{
asection **spp;
for (spp = &s->output_section->owner->sections;
*spp != s->output_section;
spp = &(*spp)->next)
;
*spp = s->output_section->next;
--s->output_section->owner->section_count;
continue;
}
/* Allocate memory for the section contents. */
s->contents = (bfd_byte *) bfd_alloc (dynobj, s->_raw_size);
if (s->contents == NULL && s->_raw_size != 0)
{
bfd_set_error (bfd_error_no_memory);
return false;
}
}
if (elf_hash_table (info)->dynamic_sections_created)
{
/* Add some entries to the .dynamic section. We fill in the
values later, in elf_i386_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. */
if (! info->shared)
{
if (! bfd_elf32_add_dynamic_entry (info, DT_DEBUG, 0))
return false;
}
if (plt)
{
if (! bfd_elf32_add_dynamic_entry (info, DT_PLTGOT, 0)
|| ! bfd_elf32_add_dynamic_entry (info, DT_PLTRELSZ, 0)
|| ! bfd_elf32_add_dynamic_entry (info, DT_PLTREL, DT_REL)
|| ! bfd_elf32_add_dynamic_entry (info, DT_JMPREL, 0))
return false;
}
if (relocs)
{
if (! bfd_elf32_add_dynamic_entry (info, DT_REL, 0)
|| ! bfd_elf32_add_dynamic_entry (info, DT_RELSZ, 0)
|| ! bfd_elf32_add_dynamic_entry (info, DT_RELENT,
sizeof (Elf32_External_Rel)))
return false;
}
if (reltext)
{
if (! bfd_elf32_add_dynamic_entry (info, DT_TEXTREL, 0))
return false;
}
}
return true;
}
/* Relocate an i386 ELF section. */
static boolean
elf_i386_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 *rel;
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);
sgot = NULL;
splt = NULL;
sreloc = NULL;
rel = relocs;
relend = relocs + input_section->reloc_count;
for (; rel < relend; rel++)
{
int r_type;
reloc_howto_type *howto;
long r_symndx;
struct elf_link_hash_entry *h;
Elf_Internal_Sym *sym;
asection *sec;
bfd_vma relocation;
bfd_reloc_status_type r;
char *shared_name;
r_type = ELF32_R_TYPE (rel->r_info);
if (r_type < 0 || r_type >= (int) R_386_max)
{
bfd_set_error (bfd_error_bad_value);
return false;
}
howto = elf_howto_table + r_type;
r_symndx = ELF32_R_SYM (rel->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)
{
bfd_vma val;
sec = local_sections[r_symndx];
val = bfd_get_32 (input_bfd, contents + rel->r_offset);
val += sec->output_offset + sym->st_value;
bfd_put_32 (input_bfd, val, contents + rel->r_offset);
}
}
continue;
}
/* This is a final link. */
h = NULL;
sym = NULL;
sec = NULL;
shared_name = NULL;
if (r_symndx < symtab_hdr->sh_info)
{
sym = local_syms + r_symndx;
sec = local_sections[r_symndx];
relocation = (sec->output_section->vma
+ sec->output_offset
+ sym->st_value);
}
else
{
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
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_386_GOTPC
|| (r_type == R_386_PLT32
&& h->plt_offset != (bfd_vma) -1)
|| (r_type == R_386_GOT32
&& elf_hash_table (info)->dynamic_sections_created)
|| (info->shared
&& (r_type == R_386_32
|| r_type == R_386_PC32)
&& (input_section->flags & SEC_ALLOC) != 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
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)
relocation = 0;
else
{
if (! ((*info->callbacks->undefined_symbol)
(info, h->root.root.string, input_bfd,
input_section, rel->r_offset)))
return false;
relocation = 0;
}
}
switch (r_type)
{
case R_386_GOT32:
/* Relocation is to the entry for this symbol in the global
offset table. */
if (sgot == NULL)
{
sgot = bfd_get_section_by_name (dynobj, ".got");
BFD_ASSERT (sgot != NULL);
}
if (h != NULL)
{
bfd_vma off;
off = h->got_offset;
BFD_ASSERT (off != (bfd_vma) -1);
if (! elf_hash_table (info)->dynamic_sections_created)
{
/* This is actually a static link. We must
initialize this entry in the global offset table.
Since the offset must always be a multiple of 4,
we use the least significant bit to record
whether we have initialized it already.
When doing a dynamic link, we create a .rel.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_32 (output_bfd, relocation,
sgot->contents + off);
h->got_offset |= 1;
}
}
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 4. 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_32 (output_bfd, relocation, sgot->contents + off);
if (info->shared)
{
asection *srelgot;
Elf_Internal_Rel outrel;
srelgot = bfd_get_section_by_name (dynobj, ".rel.got");
BFD_ASSERT (srelgot != NULL);
outrel.r_offset = (sgot->output_section->vma
+ sgot->output_offset
+ off);
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
bfd_elf32_swap_reloc_out (output_bfd, &outrel,
(((Elf32_External_Rel *)
srelgot->contents)
+ srelgot->reloc_count));
++srelgot->reloc_count;
}
local_got_offsets[r_symndx] |= 1;
}
relocation = sgot->output_offset + off;
}
break;
case R_386_GOTOFF:
/* Relocation is relative to the start of the global offset
table. */
if (sgot == NULL)
{
sgot = bfd_get_section_by_name (dynobj, ".got");
BFD_ASSERT (sgot != NULL);
}
/* Note that sgot->output_offset is not involved in this
calculation. We always want the start of .got. If we
defined _GLOBAL_OFFSET_TABLE in a different way, as is
permitted by the ABI, we might have to change this
calculation. */
relocation -= sgot->output_section->vma;
break;
case R_386_GOTPC:
/* Use global offset table as symbol value. */
if (sgot == NULL)
{
sgot = bfd_get_section_by_name (dynobj, ".got");
BFD_ASSERT (sgot != NULL);
}
relocation = sgot->output_section->vma;
break;
case R_386_PLT32:
/* Relocation is to the entry for this symbol in the
procedure linkage table. */
/* Resolve a PLT32 reloc again a local symbol directly,
without using the procedure linkage table. */
if (h == NULL)
break;
if (h->plt_offset == (bfd_vma) -1)
{
/* We didn't make a PLT entry for this symbol. This
happens when statically linking PIC code. */
break;
}
if (splt == NULL)
{
splt = bfd_get_section_by_name (dynobj, ".plt");
BFD_ASSERT (splt != NULL);
}
relocation = (splt->output_section->vma
+ splt->output_offset
+ h->plt_offset);
break;
case R_386_32:
case R_386_PC32:
if (info->shared
&& (input_section->flags & SEC_ALLOC) != 0)
{
Elf_Internal_Rel outrel;
/* When generating a shared object, these relocations
are copied into the output file to be resolved at run
time. */
if (sreloc == NULL)
{
shared_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 (shared_name == NULL)
return false;
BFD_ASSERT (strncmp (shared_name, ".rel", 4) == 0
&& strcmp (bfd_get_section_name (input_bfd,
input_section),
shared_name + 4) == 0);
sreloc = bfd_get_section_by_name (dynobj, shared_name);
BFD_ASSERT (sreloc != NULL);
}
outrel.r_offset = (rel->r_offset
+ input_section->output_section->vma
+ input_section->output_offset);
if (r_type == R_386_PC32)
{
if (!h)
{
if (! ((*info->callbacks->undefined_symbol)
(info, shared_name ? shared_name : sec->name, input_bfd,
input_section, rel->r_offset)))
bfd_set_error (bfd_error_bad_value);
return false;
}
else {
BFD_ASSERT (h->dynindx != -1);
outrel.r_info = ELF32_R_INFO (h->dynindx, R_386_PC32);
}
}
else
{
if (h == NULL)
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
else
{
BFD_ASSERT (h->dynindx != (bfd_vma) -1);
outrel.r_info = ELF32_R_INFO (h->dynindx, R_386_32);
}
}
bfd_elf32_swap_reloc_out (output_bfd, &outrel,
(((Elf32_External_Rel *)
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 (h != NULL)
continue;
}
break;
default:
break;
}
r = _bfd_final_link_relocate (howto, input_bfd, input_section,
contents, rel->r_offset,
relocation, (bfd_vma) 0);
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, rel->r_offset)))
return false;
}
break;
}
}
}
return true;
}
/* Finish up dynamic symbol handling. We set the contents of various
dynamic sections here. */
static boolean
elf_i386_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 *srel;
bfd_vma plt_index;
bfd_vma got_offset;
Elf_Internal_Rel rel;
/* 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");
srel = bfd_get_section_by_name (dynobj, ".rel.plt");
BFD_ASSERT (splt != NULL && sgot != NULL && srel != 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 4 bytes.
The first three are reserved. */
got_offset = (plt_index + 3) * 4;
/* Fill in the entry in the procedure linkage table. */
if (! info->shared)
{
memcpy (splt->contents + h->plt_offset, elf_i386_plt_entry,
PLT_ENTRY_SIZE);
bfd_put_32 (output_bfd,
(sgot->output_section->vma
+ sgot->output_offset
+ got_offset),
splt->contents + h->plt_offset + 2);
}
else
{
memcpy (splt->contents + h->plt_offset, elf_i386_pic_plt_entry,
PLT_ENTRY_SIZE);
bfd_put_32 (output_bfd, got_offset,
splt->contents + h->plt_offset + 2);
}
bfd_put_32 (output_bfd, plt_index * sizeof (Elf32_External_Rel),
splt->contents + h->plt_offset + 7);
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. */
bfd_put_32 (output_bfd,
(splt->output_section->vma
+ splt->output_offset
+ h->plt_offset
+ 6),
sgot->contents + got_offset);
/* Fill in the entry in the .rel.plt section. */
rel.r_offset = (sgot->output_section->vma
+ sgot->output_offset
+ got_offset);
rel.r_info = ELF32_R_INFO (h->dynindx, R_386_JUMP_SLOT);
bfd_elf32_swap_reloc_out (output_bfd, &rel,
((Elf32_External_Rel *) srel->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 (h->got_offset != (bfd_vma) -1)
{
asection *sgot;
asection *srel;
Elf_Internal_Rel rel;
/* This symbol has an entry in the global offset table. Set it
up. */
BFD_ASSERT (h->dynindx != -1);
sgot = bfd_get_section_by_name (dynobj, ".got");
srel = bfd_get_section_by_name (dynobj, ".rel.got");
BFD_ASSERT (sgot != NULL && srel != NULL);
bfd_put_32 (output_bfd, (bfd_vma) 0, sgot->contents + h->got_offset);
rel.r_offset = (sgot->output_section->vma
+ sgot->output_offset
+ h->got_offset);
rel.r_info = ELF32_R_INFO (h->dynindx, R_386_GLOB_DAT);
bfd_elf32_swap_reloc_out (output_bfd, &rel,
((Elf32_External_Rel *) srel->contents
+ srel->reloc_count));
++srel->reloc_count;
}
if ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_COPY) != 0)
{
asection *s;
Elf_Internal_Rel rel;
/* 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,
".rel.bss");
BFD_ASSERT (s != NULL);
rel.r_offset = (h->root.u.def.value
+ h->root.u.def.section->output_section->vma
+ h->root.u.def.section->output_offset);
rel.r_info = ELF32_R_INFO (h->dynindx, R_386_COPY);
bfd_elf32_swap_reloc_out (output_bfd, &rel,
((Elf32_External_Rel *) 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
elf_i386_finish_dynamic_sections (output_bfd, info)
bfd *output_bfd;
struct bfd_link_info *info;
{
bfd *dynobj;
asection *sgot;
asection *sdyn;
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;
Elf32_External_Dyn *dyncon, *dynconend;
splt = bfd_get_section_by_name (dynobj, ".plt");
BFD_ASSERT (splt != NULL && sdyn != NULL);
dyncon = (Elf32_External_Dyn *) sdyn->contents;
dynconend = (Elf32_External_Dyn *) (sdyn->contents + sdyn->_raw_size);
for (; dyncon < dynconend; dyncon++)
{
Elf_Internal_Dyn dyn;
const char *name;
asection *s;
bfd_elf32_swap_dyn_in (dynobj, dyncon, &dyn);
switch (dyn.d_tag)
{
default:
break;
case DT_PLTGOT:
name = ".got";
goto get_vma;
case DT_JMPREL:
name = ".rel.plt";
get_vma:
s = bfd_get_section_by_name (output_bfd, name);
BFD_ASSERT (s != NULL);
dyn.d_un.d_ptr = s->vma;
bfd_elf32_swap_dyn_out (output_bfd, &dyn, dyncon);
break;
case DT_PLTRELSZ:
s = bfd_get_section_by_name (output_bfd, ".rel.plt");
BFD_ASSERT (s != NULL);
if (s->_cooked_size != 0)
dyn.d_un.d_val = s->_cooked_size;
else
dyn.d_un.d_val = s->_raw_size;
bfd_elf32_swap_dyn_out (output_bfd, &dyn, dyncon);
break;
case DT_RELSZ:
/* My reading of the SVR4 ABI indicates that the
procedure linkage table relocs (DT_JMPREL) should be
included in the overall relocs (DT_REL). This is
what Solaris does. However, UnixWare can not handle
that case. Therefore, we override the DT_RELSZ entry
here to make it not include the JMPREL relocs. Since
the linker script arranges for .rel.plt to follow all
other relocation sections, we don't have to worry
about changing the DT_REL entry. */
s = bfd_get_section_by_name (output_bfd, ".rel.plt");
if (s != NULL)
{
if (s->_cooked_size != 0)
dyn.d_un.d_val -= s->_cooked_size;
else
dyn.d_un.d_val -= s->_raw_size;
}
bfd_elf32_swap_dyn_out (output_bfd, &dyn, dyncon);
break;
}
}
/* Fill in the first entry in the procedure linkage table. */
if (splt->_raw_size > 0)
{
if (info->shared)
memcpy (splt->contents, elf_i386_pic_plt0_entry, PLT_ENTRY_SIZE);
else
{
memcpy (splt->contents, elf_i386_plt0_entry, PLT_ENTRY_SIZE);
bfd_put_32 (output_bfd,
sgot->output_section->vma + sgot->output_offset + 4,
splt->contents + 2);
bfd_put_32 (output_bfd,
sgot->output_section->vma + sgot->output_offset + 8,
splt->contents + 8);
}
}
/* UnixWare sets the entsize of .plt to 4, although that doesn't
really seem like the right value. */
elf_section_data (splt->output_section)->this_hdr.sh_entsize = 4;
}
/* Fill in the first three entries in the global offset table. */
if (sgot->_raw_size > 0)
{
if (sdyn == NULL)
bfd_put_32 (output_bfd, (bfd_vma) 0, sgot->contents);
else
bfd_put_32 (output_bfd,
sdyn->output_section->vma + sdyn->output_offset,
sgot->contents);
bfd_put_32 (output_bfd, (bfd_vma) 0, sgot->contents + 4);
bfd_put_32 (output_bfd, (bfd_vma) 0, sgot->contents + 8);
}
elf_section_data (sgot->output_section)->this_hdr.sh_entsize = 4;
return true;
}
#define TARGET_LITTLE_SYM bfd_elf32_i386_vec
#define TARGET_LITTLE_NAME "elf32-i386"
#define ELF_ARCH bfd_arch_i386
#define ELF_MACHINE_CODE EM_386
#define elf_info_to_howto elf_i386_info_to_howto
#define elf_info_to_howto_rel elf_i386_info_to_howto_rel
#define bfd_elf32_bfd_reloc_type_lookup elf_i386_reloc_type_lookup
#define ELF_MAXPAGESIZE 0x1000
#define elf_backend_create_dynamic_sections \
_bfd_elf_create_dynamic_sections
#define elf_backend_check_relocs elf_i386_check_relocs
#define elf_backend_adjust_dynamic_symbol \
elf_i386_adjust_dynamic_symbol
#define elf_backend_size_dynamic_sections \
elf_i386_size_dynamic_sections
#define elf_backend_relocate_section elf_i386_relocate_section
#define elf_backend_finish_dynamic_symbol \
elf_i386_finish_dynamic_symbol
#define elf_backend_finish_dynamic_sections \
elf_i386_finish_dynamic_sections
#define elf_backend_want_got_plt 1
#define elf_backend_plt_readonly 0
#define elf_backend_want_plt_sym 0
#include "elf32-target.h"
Reference in New Issue View Git Blame Copy Permalink