binutils-gdb/bfd/elfxx-mips.h
Mihailo Stojanovic f16a9783c5 Add support for a MIPS specific .MIPS.xhash section.
This patch is a reimplementation of [1] which was submitted in 2015 by
Neil Schellenberger. Copyright issue was sorted out [2] last year.
It proposed a new section (.gnu.xhash) and related dynamic tag
(DT_GNU_XHASH). The new section would be virtually identical to the
existing .gnu.hash except for the translation table (xlat) which would
contain correct MIPS .dynsym indexes corresponding to the hashvals in
chains. This is because MIPS ABI imposes a different ordering on the
dynsyms than the one expected by the .gnu.hash section. Another addition
would be a leading word (ngnusyms) which would contain the number of
entries in the translation table.

  In this patch, the new section name and dynamic tag are changed to
reflect the fact that the section should be treated as MIPS-specific
(.MIPS.xhash and DT_MIPS_XHASH).

  This patch addresses the alignment issue as reported in [3], which is
caused by the leading word added to the .MIPS.xhash section. Leading word
is removed in this patch, and the number of entries in the translation
table is now calculated using DT_MIPS_SYMTABNO dynamic tag (this is
addressed by the corresponding glibc patch).

  Suggestions on coding style in [4] were taken into account. Existing
GNU hash testcase was covered, and another one was added in the MIPS
part of the testsuite.

  The other major change is reserving MIPS ABI version 5 for .MIPS.xhash,
marking the need of support for .MIPS.xhash in the dynamic linker (again,
addressed in the corresponding glibc patch). This is something which I
am not sure of, especially after reading [5]. I am confused on whether
this ABI version is reserved for IFUNC, or it can be used for this
purpose.

Already mentioned glibc patch is submitted at:
https://sourceware.org/ml/libc-alpha/2019-06/msg00456.html

[1] https://sourceware.org/ml/binutils/2015-10/msg00057.html
[2] https://sourceware.org/ml/binutils/2018-03/msg00025.html
[3] https://sourceware.org/ml/binutils/2016-01/msg00006.html
[4] https://sourceware.org/ml/binutils/2016-02/msg00097.html
[5] https://sourceware.org/ml/libc-alpha/2016-12/msg00853.html

ld      * emulparams/elf32bmip.sh: Add .MIPS.xhash section.
        * emulparams/elf32bmipn32-defs.sh: Add .MIPS.xhash section.
        * emulparams/elf64bmip-defs.sh: Add .MIPS.xhash section.
        * emultempl/mipself.em: Remove mips_after_parse function.
        * testsuite/ld-elf/hash.d: Update comment.
        * testsuite/ld-mips-elf/hash1.d: New test.
        * testsuite/ld-mips-elf/hash1.s: Ditto.
        * testsuite/ld-mips-elf/hash1a.d: Remove.
        * testsuite/ld-mips-elf/hash1b.d: Ditto.
        * testsuite/ld-mips-elf/hash1c.d: Ditto
        * testsuite/ld-mips-elf/hash2.d: New test.
        * testsuite/ld-mips-elf/mips-elf.exp: New tests.
        * testsuite/ld-mips-elf/start.s: New test.

bfd     * elf-bfd.h (struct elf_backend_data): New members.
        * elflink.c (_bfd_elf_link_create_dynamic_sections): Create
        .gnu.hash section if necessary.
        (struct collect_gnu_hash_codes): New member.
        (elf_gnu_hash_process_symidx): New function name.
        (elf_renumber_gnu_hash_syms): Ignore local and undefined
        symbols. Record xlat location for every symbol which should have
        a .MIPS.xhash entry.
        (bfd_elf_size_dynamic_sections): Add DT_GNU_HASH dynamic tag to
        dynamic section if necessary.
        (GNU_HASH_SECTION_NAME): New define.
        (bfd_elf_size_dynsym_hash_dynstr): Get .MIPS.xhash section.
        Update the section size info.
        * elfxx-mips.c (struct mips_elf_hash_sort_data): New members.
        (struct mips_elf_link_hash_entry): New member.
        (mips_elf_link_hash_newfunc): Initialize .MIPS.xhash translation
        table location.
        (mips_elf_sort_hash_table): Initialize the pointer to the
        .MIPS.xhash section.
        (mips_elf_sort_hash_table_f): Populate the .MIPS.xhash
        translation table entry with the symbol dynindx.
        (_bfd_mips_elf_section_from_shdr): Add SHT_MIPS_XHASH.
        (_bfd_mips_elf_fake_sections): Initialize .MIPS.xhash section
        info.
        (_bfd_mips_elf_create_dynamic_sections): Create .MIPS.xhash
        section.
        (_bfd_mips_elf_size_dynamic_sections): Add DT_MIPS_XHASH tag to
        dynamic section.
        (_bfd_mips_elf_finish_synamic_sections): Add DT_MIPS_XHASH.
        (_bfd_mips_elf_final_write_processing): Set .MIPS.xhash section
        sh_link info.
        (_bfd_mips_elf_get_target_dtag): Get DT_MIPS_XHASH tag.
        (MIPS_LIBC_ABI_XHASH): New ABI version enum value.
        (_bfd_mips_post_process_headers): Mark the ABI version as
        MIPS_LIBC_ABI_XHASH if there exists a .MIPS.xhash section,
        but not a .hash section.
        (_bfd_mips_elf_record_xhash_symbol): New function. Record a
        position in the translation table, associated with the hash
        entry.
        * elfxx-mips.h (literal_reloc_p): Define
        elf_backend_record_xhash_symbol backend hook.
        * elfxx-target.h: Initialize elf_backend_record_xhash_symbol
        backend hook.

include * elf/mips.h (SHT_GNU_XHASH): New define.
        (DT_GNU_XHASH): New define.

binutils * readelf.c (get_mips_dynamic_type): Return MIPS_XHASH dynamic type.
        (get_mips_section_type_name): Return MI{S_XHASH name string.
        (dynamic_section_mips_val): Initialize the .MIPS.xhash dynamic
        info.
        (process_symbol_table): Initialize the .MIPS.xhash section
        pointer. Adjust the readelf output to support the new section.
        (process_object): Set the .MIPS.xhash dynamic info to zero.
2019-08-09 11:06:37 +01:00

206 lines
8.9 KiB
C

/* MIPS ELF specific backend routines.
Copyright (C) 2002-2019 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 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#include "elf/common.h"
#include "elf/internal.h"
#include "elf/mips.h"
extern bfd_boolean _bfd_mips_elf_mkobject
(bfd *);
extern bfd_boolean _bfd_mips_elf_new_section_hook
(bfd *, asection *);
extern void _bfd_mips_elf_symbol_processing
(bfd *, asymbol *);
extern unsigned int _bfd_mips_elf_eh_frame_address_size
(bfd *, const asection *);
extern bfd_boolean _bfd_mips_elf_name_local_section_symbols
(bfd *);
extern bfd_boolean _bfd_mips_elf_section_processing
(bfd *, Elf_Internal_Shdr *);
extern bfd_boolean _bfd_mips_elf_section_from_shdr
(bfd *, Elf_Internal_Shdr *, const char *, int);
extern bfd_boolean _bfd_mips_elf_fake_sections
(bfd *, Elf_Internal_Shdr *, asection *);
extern bfd_boolean _bfd_mips_elf_section_from_bfd_section
(bfd *, asection *, int *);
extern bfd_boolean _bfd_mips_elf_add_symbol_hook
(bfd *, struct bfd_link_info *, Elf_Internal_Sym *,
const char **, flagword *, asection **, bfd_vma *);
extern int _bfd_mips_elf_link_output_symbol_hook
(struct bfd_link_info *, const char *, Elf_Internal_Sym *,
asection *, struct elf_link_hash_entry *);
extern bfd_boolean _bfd_mips_elf_create_dynamic_sections
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_check_relocs
(bfd *, struct bfd_link_info *, asection *, const Elf_Internal_Rela *);
extern bfd_boolean _bfd_mips_elf_adjust_dynamic_symbol
(struct bfd_link_info *, struct elf_link_hash_entry *);
extern bfd_boolean _bfd_mips_elf_always_size_sections
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_size_dynamic_sections
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_relocate_section
(bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
Elf_Internal_Rela *, Elf_Internal_Sym *, asection **);
extern bfd_boolean _bfd_mips_elf_finish_dynamic_symbol
(bfd *, struct bfd_link_info *, struct elf_link_hash_entry *,
Elf_Internal_Sym *);
extern bfd_boolean _bfd_mips_vxworks_finish_dynamic_symbol
(bfd *, struct bfd_link_info *, struct elf_link_hash_entry *,
Elf_Internal_Sym *);
extern bfd_boolean _bfd_mips_elf_finish_dynamic_sections
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_sort_relocs_p
(asection *);
extern void _bfd_mips_final_write_processing
(bfd *);
extern bfd_boolean _bfd_mips_elf_final_write_processing
(bfd *);
extern int _bfd_mips_elf_additional_program_headers
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_modify_segment_map
(bfd *, struct bfd_link_info *);
extern asection * _bfd_mips_elf_gc_mark_hook
(asection *, struct bfd_link_info *, Elf_Internal_Rela *,
struct elf_link_hash_entry *, Elf_Internal_Sym *);
extern void _bfd_mips_elf_copy_indirect_symbol
(struct bfd_link_info *, struct elf_link_hash_entry *,
struct elf_link_hash_entry *);
extern void _bfd_mips_elf_hide_symbol
(struct bfd_link_info *, struct elf_link_hash_entry *, bfd_boolean);
extern bfd_boolean _bfd_mips_elf_ignore_discarded_relocs
(asection *);
extern bfd_boolean _bfd_mips_elf_is_target_special_symbol
(bfd *abfd, asymbol *sym);
extern bfd_boolean _bfd_mips_elf_find_nearest_line
(bfd *, asymbol **, asection *, bfd_vma,
const char **, const char **, unsigned int *, unsigned int *);
extern bfd_boolean _bfd_mips_elf_find_inliner_info
(bfd *, const char **, const char **, unsigned int *);
extern bfd_boolean _bfd_mips_elf_set_section_contents
(bfd *, asection *, const void *, file_ptr, bfd_size_type);
extern bfd_byte *_bfd_elf_mips_get_relocated_section_contents
(bfd *, struct bfd_link_info *, struct bfd_link_order *,
bfd_byte *, bfd_boolean, asymbol **);
extern bfd_boolean _bfd_mips_elf_relax_section
(bfd *abfd, asection *sec, struct bfd_link_info *link_info,
bfd_boolean *again);
extern struct bfd_link_hash_table *_bfd_mips_elf_link_hash_table_create
(bfd *);
extern struct bfd_link_hash_table *_bfd_mips_vxworks_link_hash_table_create
(bfd *);
extern bfd_boolean _bfd_mips_elf_final_link
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_merge_private_bfd_data
(bfd *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_set_private_flags
(bfd *, flagword);
extern const char * _bfd_mips_fp_abi_string
(int);
extern bfd_boolean _bfd_mips_elf_print_private_bfd_data
(bfd *, void *);
extern bfd_boolean _bfd_mips_elf_discard_info
(bfd *, struct elf_reloc_cookie *, struct bfd_link_info *);
extern bfd_boolean _bfd_mips_elf_write_section
(bfd *, struct bfd_link_info *, asection *, bfd_byte *);
extern bfd_boolean _bfd_mips_elf_read_ecoff_info
(bfd *, asection *, struct ecoff_debug_info *);
extern void _bfd_mips_elf_reloc_unshuffle
(bfd *, int, bfd_boolean, bfd_byte *);
extern void _bfd_mips_elf_reloc_shuffle
(bfd *, int, bfd_boolean, bfd_byte *);
extern bfd_reloc_status_type _bfd_mips_elf_gprel16_with_gp
(bfd *, asymbol *, arelent *, asection *, bfd_boolean, void *, bfd_vma);
extern bfd_reloc_status_type _bfd_mips_elf32_gprel16_reloc
(bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
extern bfd_reloc_status_type _bfd_mips_elf_hi16_reloc
(bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
extern bfd_reloc_status_type _bfd_mips_elf_got16_reloc
(bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
extern bfd_reloc_status_type _bfd_mips_elf_lo16_reloc
(bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
extern bfd_reloc_status_type _bfd_mips_elf_generic_reloc
(bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
extern unsigned long _bfd_elf_mips_mach
(flagword);
extern bfd_vma _bfd_mips_elf_sign_extend
(bfd_vma, int);
extern void _bfd_mips_elf_merge_symbol_attribute
(struct elf_link_hash_entry *, const Elf_Internal_Sym *, bfd_boolean, bfd_boolean);
extern char *_bfd_mips_elf_get_target_dtag (bfd_vma);
extern bfd_boolean _bfd_mips_elf_ignore_undef_symbol
(struct elf_link_hash_entry *);
extern void _bfd_mips_elf_use_plts_and_copy_relocs
(struct bfd_link_info *);
extern void _bfd_mips_elf_linker_flags
(struct bfd_link_info *, bfd_boolean, bfd_boolean, bfd_boolean);
extern void _bfd_mips_elf_compact_branches
(struct bfd_link_info *, bfd_boolean);
extern bfd_boolean _bfd_mips_elf_init_stubs
(struct bfd_link_info *,
asection *(*) (const char *, asection *, asection *));
extern bfd_vma _bfd_mips_elf_plt_sym_val
(bfd_vma, const asection *, const arelent *rel);
extern long _bfd_mips_elf_get_synthetic_symtab
(bfd *, long, asymbol **, long, asymbol **, asymbol **);
extern bfd_boolean _bfd_mips_elf_gc_mark_extra_sections
(struct bfd_link_info *, elf_gc_mark_hook_fn);
extern void _bfd_mips_post_process_headers
(bfd *abfd, struct bfd_link_info *link_info);
extern const struct bfd_elf_special_section _bfd_mips_elf_special_sections [];
extern bfd_boolean _bfd_mips_elf_common_definition (Elf_Internal_Sym *);
extern int _bfd_mips_elf_compact_eh_encoding (struct bfd_link_info *);
extern int _bfd_mips_elf_cant_unwind_opcode (struct bfd_link_info *);
extern void _bfd_mips_elf_record_xhash_symbol
(struct elf_link_hash_entry *h, bfd_vma xlat_loc);
static inline bfd_boolean
gprel16_reloc_p (unsigned int r_type)
{
return (r_type == R_MIPS_GPREL16
|| r_type == R_MIPS16_GPREL
|| r_type == R_MICROMIPS_GPREL16
|| r_type == R_MICROMIPS_GPREL7_S2);
}
static inline bfd_boolean
literal_reloc_p (int r_type)
{
return r_type == R_MIPS_LITERAL || r_type == R_MICROMIPS_LITERAL;
}
#define elf_backend_common_definition _bfd_mips_elf_common_definition
#define elf_backend_name_local_section_symbols \
_bfd_mips_elf_name_local_section_symbols
#define elf_backend_special_sections _bfd_mips_elf_special_sections
#define elf_backend_eh_frame_address_size _bfd_mips_elf_eh_frame_address_size
#define elf_backend_merge_symbol_attribute _bfd_mips_elf_merge_symbol_attribute
#define elf_backend_ignore_undef_symbol _bfd_mips_elf_ignore_undef_symbol
#define elf_backend_post_process_headers _bfd_mips_post_process_headers
#define elf_backend_compact_eh_encoding _bfd_mips_elf_compact_eh_encoding
#define elf_backend_cant_unwind_opcode _bfd_mips_elf_cant_unwind_opcode
#define elf_backend_record_xhash_symbol _bfd_mips_elf_record_xhash_symbol
#define elf_backend_always_renumber_dynsyms TRUE