523 lines
17 KiB
C
523 lines
17 KiB
C
/* x86 specific support for ELF
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "sysdep.h"
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#include "bfd.h"
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#include "bfdlink.h"
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#include "libbfd.h"
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#include "elf-bfd.h"
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#include "bfd_stdint.h"
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#include "hashtab.h"
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#define PLT_CIE_LENGTH 20
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#define PLT_FDE_LENGTH 36
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#define PLT_FDE_START_OFFSET 4 + PLT_CIE_LENGTH + 8
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#define PLT_FDE_LEN_OFFSET 4 + PLT_CIE_LENGTH + 12
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#define ABI_64_P(abfd) \
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(get_elf_backend_data (abfd)->s->elfclass == ELFCLASS64)
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/* If ELIMINATE_COPY_RELOCS is non-zero, the linker will try to avoid
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copying dynamic variables from a shared lib into an app's dynbss
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section, and instead use a dynamic relocation to point into the
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shared lib. */
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#define ELIMINATE_COPY_RELOCS 1
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#define elf_x86_hash_table(p, id) \
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(is_elf_hash_table ((p)->hash) \
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&& elf_hash_table_id ((struct elf_link_hash_table *) ((p)->hash)) == (id) \
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? ((struct elf_x86_link_hash_table *) ((p)->hash)) : NULL)
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/* Is a undefined weak symbol which is resolved to 0. Reference to an
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undefined weak symbol is resolved to 0 when building executable if
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it isn't dynamic and
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1. Has non-GOT/non-PLT relocations in text section. Or
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2. Has no GOT/PLT relocation.
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Local undefined weak symbol is always resolved to 0.
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*/
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#define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, ID, GOT_RELOC, EH) \
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((EH)->elf.root.type == bfd_link_hash_undefweak \
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&& ((EH)->elf.forced_local \
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|| (bfd_link_executable (INFO) \
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&& (elf_x86_hash_table ((INFO), (ID))->interp == NULL \
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|| !(GOT_RELOC) \
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|| (EH)->has_non_got_reloc \
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|| !(INFO)->dynamic_undefined_weak))))
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/* Should copy relocation be generated for a symbol. Don't generate
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copy relocation against a protected symbol defined in a shared
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object with GNU_PROPERTY_NO_COPY_ON_PROTECTED. */
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#define SYMBOL_NO_COPYRELOC(INFO, EH) \
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((EH)->def_protected \
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&& ((EH)->elf.root.type == bfd_link_hash_defined \
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|| (EH)->elf.root.type == bfd_link_hash_defweak) \
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&& elf_has_no_copy_on_protected ((EH)->elf.root.u.def.section->owner) \
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&& ((EH)->elf.root.u.def.section->owner->flags & DYNAMIC) != 0 \
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&& ((EH)->elf.root.u.def.section->flags & SEC_CODE) == 0)
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/* x86 ELF linker hash entry. */
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struct elf_x86_link_hash_entry
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{
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struct elf_link_hash_entry elf;
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/* Track dynamic relocs copied for this symbol. */
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struct elf_dyn_relocs *dyn_relocs;
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unsigned char tls_type;
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/* TRUE if symbol has GOT or PLT relocations. */
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unsigned int has_got_reloc : 1;
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/* TRUE if symbol has non-GOT/non-PLT relocations in text sections. */
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unsigned int has_non_got_reloc : 1;
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/* Don't call finish_dynamic_symbol on this symbol. */
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unsigned int no_finish_dynamic_symbol : 1;
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/* TRUE if symbol is __tls_get_addr. */
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unsigned int tls_get_addr : 1;
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/* TRUE if symbol is defined as a protected symbol. */
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unsigned int def_protected : 1;
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/* Symbol is referenced by R_386_GOTOFF relocation. This is only used
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by i386. */
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unsigned int gotoff_ref : 1;
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/* TRUE if a weak symbol with a real definition needs a copy reloc.
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When there is a weak symbol with a real definition, the processor
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independent code will have arranged for us to see the real
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definition first. We need to copy the needs_copy bit from the
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real definition and check it when allowing copy reloc in PIE. This
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is only used by x86-64. */
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unsigned int needs_copy : 1;
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/* Reference count of C/C++ function pointer relocations in read-write
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section which can be resolved at run-time. */
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bfd_signed_vma func_pointer_refcount;
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/* Information about the GOT PLT entry. Filled when there are both
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GOT and PLT relocations against the same function. */
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union gotplt_union plt_got;
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/* Information about the second PLT entry. */
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union gotplt_union plt_second;
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/* Offset of the GOTPLT entry reserved for the TLS descriptor,
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starting at the end of the jump table. */
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bfd_vma tlsdesc_got;
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};
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struct elf_x86_lazy_plt_layout
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{
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/* The first entry in an absolute lazy procedure linkage table looks
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like this. */
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const bfd_byte *plt0_entry;
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unsigned int plt0_entry_size; /* Size of PLT0 entry. */
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/* Later entries in an absolute lazy procedure linkage table look
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like this. */
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const bfd_byte *plt_entry;
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unsigned int plt_entry_size; /* Size of each PLT entry. */
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/* Offsets into plt0_entry that are to be replaced with GOT[1] and
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GOT[2]. */
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unsigned int plt0_got1_offset;
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unsigned int plt0_got2_offset;
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/* Offset of the end of the PC-relative instruction containing
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plt0_got2_offset. This is for x86-64 only. */
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unsigned int plt0_got2_insn_end;
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/* Offsets into plt_entry that are to be replaced with... */
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unsigned int plt_got_offset; /* ... address of this symbol in .got. */
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unsigned int plt_reloc_offset; /* ... offset into relocation table. */
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unsigned int plt_plt_offset; /* ... offset to start of .plt. */
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/* Length of the PC-relative instruction containing plt_got_offset.
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This is used for x86-64 only. */
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unsigned int plt_got_insn_size;
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/* Offset of the end of the PC-relative jump to plt0_entry. This is
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used for x86-64 only. */
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unsigned int plt_plt_insn_end;
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/* Offset into plt_entry where the initial value of the GOT entry
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points. */
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unsigned int plt_lazy_offset;
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/* The first entry in a PIC lazy procedure linkage table looks like
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this. */
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const bfd_byte *pic_plt0_entry;
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/* Subsequent entries in a PIC lazy procedure linkage table look
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like this. */
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const bfd_byte *pic_plt_entry;
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/* .eh_frame covering the lazy .plt section. */
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const bfd_byte *eh_frame_plt;
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unsigned int eh_frame_plt_size;
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};
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struct elf_x86_non_lazy_plt_layout
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{
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/* Entries in an absolute non-lazy procedure linkage table look like
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this. */
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const bfd_byte *plt_entry;
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/* Entries in a PIC non-lazy procedure linkage table look like this. */
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const bfd_byte *pic_plt_entry;
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unsigned int plt_entry_size; /* Size of each PLT entry. */
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/* Offsets into plt_entry that are to be replaced with... */
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unsigned int plt_got_offset; /* ... address of this symbol in .got. */
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/* Length of the PC-relative instruction containing plt_got_offset.
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This is used for x86-64 only. */
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unsigned int plt_got_insn_size;
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/* .eh_frame covering the non-lazy .plt section. */
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const bfd_byte *eh_frame_plt;
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unsigned int eh_frame_plt_size;
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};
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struct elf_x86_plt_layout
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{
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/* The first entry in a lazy procedure linkage table looks like this.
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This is only used for i386 where absolute PLT0 and PIC PLT0 are
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different. */
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const bfd_byte *plt0_entry;
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/* Entries in a procedure linkage table look like this. */
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const bfd_byte *plt_entry;
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unsigned int plt_entry_size; /* Size of each PLT entry. */
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/* 1 has PLT0. */
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unsigned int has_plt0;
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/* Offsets into plt_entry that are to be replaced with... */
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unsigned int plt_got_offset; /* ... address of this symbol in .got. */
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/* Length of the PC-relative instruction containing plt_got_offset.
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This is only used for x86-64. */
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unsigned int plt_got_insn_size;
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/* .eh_frame covering the .plt section. */
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const bfd_byte *eh_frame_plt;
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unsigned int eh_frame_plt_size;
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};
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/* Values in tls_type of x86 ELF linker hash entry. */
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#define GOT_UNKNOWN 0
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#define GOT_NORMAL 1
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#define GOT_TLS_GD 2
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#define GOT_TLS_IE 4
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#define GOT_TLS_IE_POS 5
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#define GOT_TLS_IE_NEG 6
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#define GOT_TLS_IE_BOTH 7
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#define GOT_TLS_GDESC 8
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#define GOT_TLS_GD_BOTH_P(type) \
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((type) == (GOT_TLS_GD | GOT_TLS_GDESC))
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#define GOT_TLS_GD_P(type) \
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((type) == GOT_TLS_GD || GOT_TLS_GD_BOTH_P (type))
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#define GOT_TLS_GDESC_P(type) \
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((type) == GOT_TLS_GDESC || GOT_TLS_GD_BOTH_P (type))
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#define GOT_TLS_GD_ANY_P(type) \
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(GOT_TLS_GD_P (type) || GOT_TLS_GDESC_P (type))
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#define elf_x86_hash_entry(ent) \
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((struct elf_x86_link_hash_entry *)(ent))
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/* x86 ELF linker hash table. */
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struct elf_x86_link_hash_table
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{
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struct elf_link_hash_table elf;
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/* Short-cuts to get to dynamic linker sections. */
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asection *interp;
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asection *plt_eh_frame;
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asection *plt_second;
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asection *plt_second_eh_frame;
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asection *plt_got;
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asection *plt_got_eh_frame;
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/* Parameters describing PLT generation, lazy or non-lazy. */
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struct elf_x86_plt_layout plt;
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/* Parameters describing lazy PLT generation. */
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const struct elf_x86_lazy_plt_layout *lazy_plt;
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/* Parameters describing non-lazy PLT generation. */
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const struct elf_x86_non_lazy_plt_layout *non_lazy_plt;
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union
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{
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bfd_signed_vma refcount;
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bfd_vma offset;
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} tls_ld_or_ldm_got;
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/* The amount of space used by the jump slots in the GOT. */
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bfd_vma sgotplt_jump_table_size;
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/* Small local sym cache. */
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struct sym_cache sym_cache;
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/* _TLS_MODULE_BASE_ symbol. */
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struct bfd_link_hash_entry *tls_module_base;
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/* Used by local STT_GNU_IFUNC symbols. */
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htab_t loc_hash_table;
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void * loc_hash_memory;
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/* The offset into sgot of the GOT entry used by the PLT entry
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above. */
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bfd_vma tlsdesc_got;
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/* The index of the next R_X86_64_JUMP_SLOT entry in .rela.plt. */
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bfd_vma next_jump_slot_index;
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/* The index of the next R_X86_64_IRELATIVE entry in .rela.plt. */
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bfd_vma next_irelative_index;
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/* TRUE if there are dynamic relocs against IFUNC symbols that apply
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to read-only sections. */
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bfd_boolean readonly_dynrelocs_against_ifunc;
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/* TRUE if this is a VxWorks x86 target. This is only used for
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i386. */
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bfd_boolean is_vxworks;
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/* The (unloaded but important) .rel.plt.unloaded section on VxWorks.
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This is used for i386 only. */
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asection *srelplt2;
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/* The index of the next unused R_386_TLS_DESC slot in .rel.plt. This
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is only used for i386. */
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bfd_vma next_tls_desc_index;
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/* The offset into splt of the PLT entry for the TLS descriptor
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resolver. Special values are 0, if not necessary (or not found
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to be necessary yet), and -1 if needed but not determined
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yet. This is only used for x86-64. */
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bfd_vma tlsdesc_plt;
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bfd_vma (*r_info) (bfd_vma, bfd_vma);
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bfd_vma (*r_sym) (bfd_vma);
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bfd_boolean (*convert_load) (bfd *, asection *,
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struct bfd_link_info *);
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bfd_boolean (*is_reloc_section) (const char *);
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enum elf_target_id target_id;
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unsigned int sizeof_reloc;
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unsigned int dt_reloc;
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unsigned int dt_reloc_sz;
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unsigned int dt_reloc_ent;
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unsigned int got_entry_size;
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unsigned int pointer_r_type;
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int dynamic_interpreter_size;
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const char *dynamic_interpreter;
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const char *tls_get_addr;
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};
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struct elf_x86_plt_layout_table
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{
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/* The lazy PLT layout. */
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const struct elf_x86_lazy_plt_layout *lazy_plt;
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/* The non-lazy PLT layout. */
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const struct elf_x86_non_lazy_plt_layout *non_lazy_plt;
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/* The lazy PLT layout for IBT. */
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const struct elf_x86_lazy_plt_layout *lazy_ibt_plt;
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/* The non-lazy PLT layout for IBT. */
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const struct elf_x86_non_lazy_plt_layout *non_lazy_ibt_plt;
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/* TRUE if this is a normal x86 target. */
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bfd_boolean normal_target;
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/* TRUE if this is a VxWorks x86 target. */
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bfd_boolean is_vxworks;
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};
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struct elf_x86_obj_tdata
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{
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struct elf_obj_tdata root;
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/* tls_type for each local got entry. */
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char *local_got_tls_type;
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/* GOTPLT entries for TLS descriptors. */
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bfd_vma *local_tlsdesc_gotent;
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};
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enum elf_x86_plt_type
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{
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plt_non_lazy = 0,
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plt_lazy = 1 << 0,
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plt_pic = 1 << 1,
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plt_second = 1 << 2,
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plt_unknown = -1
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};
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struct elf_x86_plt
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{
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const char *name;
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asection *sec;
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bfd_byte *contents;
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enum elf_x86_plt_type type;
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unsigned int plt_got_offset;
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unsigned int plt_entry_size;
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unsigned int plt_got_insn_size; /* Only used for x86-64. */
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long count;
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};
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#define elf_x86_tdata(abfd) \
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((struct elf_x86_obj_tdata *) (abfd)->tdata.any)
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#define elf_x86_local_got_tls_type(abfd) \
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(elf_x86_tdata (abfd)->local_got_tls_type)
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#define elf_x86_local_tlsdesc_gotent(abfd) \
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(elf_x86_tdata (abfd)->local_tlsdesc_gotent)
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#define elf_x86_compute_jump_table_size(htab) \
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((htab)->elf.srelplt->reloc_count * (htab)->got_entry_size)
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#define is_x86_elf(bfd, htab) \
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(bfd_get_flavour (bfd) == bfd_target_elf_flavour \
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&& elf_tdata (bfd) != NULL \
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&& elf_object_id (bfd) == (htab)->target_id)
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extern bfd_boolean _bfd_i386_elf_convert_load
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(bfd *, asection *, struct bfd_link_info *);
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extern bfd_boolean _bfd_x86_64_elf_convert_load
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(bfd *, asection *, struct bfd_link_info *);
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extern bfd_boolean _bfd_x86_elf_mkobject
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(bfd *);
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extern void _bfd_x86_elf_set_tls_module_base
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(struct bfd_link_info *);
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extern bfd_vma _bfd_x86_elf_dtpoff_base
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(struct bfd_link_info *);
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extern bfd_boolean _bfd_x86_elf_readonly_dynrelocs
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(struct elf_link_hash_entry *, void *);
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extern struct elf_link_hash_entry * _bfd_elf_x86_get_local_sym_hash
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(struct elf_x86_link_hash_table *, bfd *, const Elf_Internal_Rela *,
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bfd_boolean);
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extern hashval_t _bfd_x86_elf_local_htab_hash
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(const void *);
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extern int _bfd_x86_elf_local_htab_eq
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(const void *, const void *);
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extern struct bfd_hash_entry * _bfd_x86_elf_link_hash_newfunc
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(struct bfd_hash_entry *, struct bfd_hash_table *, const char *);
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extern struct bfd_link_hash_table * _bfd_x86_elf_link_hash_table_create
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(bfd *);
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extern int _bfd_x86_elf_compare_relocs
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(const void *, const void *);
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extern bfd_boolean _bfd_x86_elf_link_check_relocs
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(bfd *, struct bfd_link_info *);
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extern bfd_boolean _bfd_x86_elf_size_dynamic_sections
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(bfd *, struct bfd_link_info *);
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extern bfd_boolean _bfd_x86_elf_always_size_sections
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(bfd *, struct bfd_link_info *);
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extern void _bfd_x86_elf_merge_symbol_attribute
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(struct elf_link_hash_entry *, const Elf_Internal_Sym *,
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bfd_boolean, bfd_boolean);
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extern void _bfd_x86_elf_copy_indirect_symbol
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(struct bfd_link_info *, struct elf_link_hash_entry *,
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struct elf_link_hash_entry *);
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extern bfd_boolean _bfd_x86_elf_fixup_symbol
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(struct bfd_link_info *, struct elf_link_hash_entry *);
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extern bfd_boolean _bfd_x86_elf_hash_symbol
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(struct elf_link_hash_entry *);
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extern bfd_boolean _bfd_x86_elf_adjust_dynamic_symbol
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(struct bfd_link_info *, struct elf_link_hash_entry *);
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extern asection * _bfd_x86_elf_gc_mark_hook
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(asection *, struct bfd_link_info *, Elf_Internal_Rela *,
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struct elf_link_hash_entry *, Elf_Internal_Sym *);
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extern long _bfd_x86_elf_get_synthetic_symtab
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(bfd *, long, long, bfd_vma, struct elf_x86_plt [], asymbol **,
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asymbol **);
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extern enum elf_property_kind _bfd_x86_elf_parse_gnu_properties
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(bfd *, unsigned int, bfd_byte *, unsigned int);
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extern bfd_boolean _bfd_x86_elf_merge_gnu_properties
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(struct bfd_link_info *, bfd *, elf_property *, elf_property *);
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extern bfd * _bfd_x86_elf_link_setup_gnu_properties
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(struct bfd_link_info *, struct elf_x86_plt_layout_table *);
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#define bfd_elf64_mkobject \
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_bfd_x86_elf_mkobject
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#define bfd_elf32_mkobject \
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_bfd_x86_elf_mkobject
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#define bfd_elf64_bfd_link_hash_table_create \
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_bfd_x86_elf_link_hash_table_create
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#define bfd_elf32_bfd_link_hash_table_create \
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_bfd_x86_elf_link_hash_table_create
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#define bfd_elf64_bfd_link_check_relocs \
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_bfd_x86_elf_link_check_relocs
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#define bfd_elf32_bfd_link_check_relocs \
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_bfd_x86_elf_link_check_relocs
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#define elf_backend_size_dynamic_sections \
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_bfd_x86_elf_size_dynamic_sections
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#define elf_backend_always_size_sections \
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_bfd_x86_elf_always_size_sections
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#define elf_backend_merge_symbol_attribute \
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_bfd_x86_elf_merge_symbol_attribute
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#define elf_backend_copy_indirect_symbol \
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_bfd_x86_elf_copy_indirect_symbol
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#define elf_backend_fixup_symbol \
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_bfd_x86_elf_fixup_symbol
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#define elf_backend_hash_symbol \
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_bfd_x86_elf_hash_symbol
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#define elf_backend_adjust_dynamic_symbol \
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_bfd_x86_elf_adjust_dynamic_symbol
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#define elf_backend_gc_mark_hook \
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_bfd_x86_elf_gc_mark_hook
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#define elf_backend_omit_section_dynsym \
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((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true)
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#define elf_backend_parse_gnu_properties \
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_bfd_x86_elf_parse_gnu_properties
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#define elf_backend_merge_gnu_properties \
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_bfd_x86_elf_merge_gnu_properties
|