| /* x86 specific support for ELF |
| Copyright (C) 2017 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 "sysdep.h" |
| #include "bfd.h" |
| #include "bfdlink.h" |
| #include "libbfd.h" |
| #include "elf-bfd.h" |
| #include "bfd_stdint.h" |
| #include "hashtab.h" |
| |
| #define PLT_CIE_LENGTH 20 |
| #define PLT_FDE_LENGTH 36 |
| #define PLT_FDE_START_OFFSET 4 + PLT_CIE_LENGTH + 8 |
| #define PLT_FDE_LEN_OFFSET 4 + PLT_CIE_LENGTH + 12 |
| |
| #define ABI_64_P(abfd) \ |
| (get_elf_backend_data (abfd)->s->elfclass == ELFCLASS64) |
| |
| /* If ELIMINATE_COPY_RELOCS is non-zero, the linker will try to avoid |
| copying dynamic variables from a shared lib into an app's dynbss |
| section, and instead use a dynamic relocation to point into the |
| shared lib. */ |
| #define ELIMINATE_COPY_RELOCS 1 |
| |
| #define elf_x86_hash_table(p, id) \ |
| (is_elf_hash_table ((p)->hash) \ |
| && elf_hash_table_id ((struct elf_link_hash_table *) ((p)->hash)) == (id) \ |
| ? ((struct elf_x86_link_hash_table *) ((p)->hash)) : NULL) |
| |
| /* Will references to this symbol always be local in this object? */ |
| #define SYMBOL_REFERENCES_LOCAL_P(INFO, H) \ |
| _bfd_x86_elf_link_symbol_references_local ((INFO), (H)) |
| |
| /* Is a undefined weak symbol which is resolved to 0. Reference to an |
| undefined weak symbol is resolved to 0 when building executable if |
| it isn't dynamic and |
| 1. Has non-GOT/non-PLT relocations in text section. Or |
| 2. Has no GOT/PLT relocation. |
| Local undefined weak symbol is always resolved to 0. |
| */ |
| #define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, EH) \ |
| ((EH)->elf.root.type == bfd_link_hash_undefweak \ |
| && (SYMBOL_REFERENCES_LOCAL_P ((INFO), &(EH)->elf) \ |
| || (bfd_link_executable (INFO) \ |
| && (!(EH)->has_got_reloc \ |
| || (EH)->has_non_got_reloc)))) |
| |
| /* Should copy relocation be generated for a symbol. Don't generate |
| copy relocation against a protected symbol defined in a shared |
| object with GNU_PROPERTY_NO_COPY_ON_PROTECTED. */ |
| #define SYMBOL_NO_COPYRELOC(INFO, EH) \ |
| ((EH)->def_protected \ |
| && ((EH)->elf.root.type == bfd_link_hash_defined \ |
| || (EH)->elf.root.type == bfd_link_hash_defweak) \ |
| && elf_has_no_copy_on_protected ((EH)->elf.root.u.def.section->owner) \ |
| && ((EH)->elf.root.u.def.section->owner->flags & DYNAMIC) != 0 \ |
| && ((EH)->elf.root.u.def.section->flags & SEC_CODE) == 0) |
| |
| /* x86 ELF linker hash entry. */ |
| |
| struct elf_x86_link_hash_entry |
| { |
| struct elf_link_hash_entry elf; |
| |
| /* Track dynamic relocs copied for this symbol. */ |
| struct elf_dyn_relocs *dyn_relocs; |
| |
| unsigned char tls_type; |
| |
| /* TRUE if symbol has GOT or PLT relocations. */ |
| unsigned int has_got_reloc : 1; |
| |
| /* TRUE if symbol has non-GOT/non-PLT relocations in text sections. */ |
| unsigned int has_non_got_reloc : 1; |
| |
| /* Don't call finish_dynamic_symbol on this symbol. */ |
| unsigned int no_finish_dynamic_symbol : 1; |
| |
| /* TRUE if symbol is __tls_get_addr. */ |
| unsigned int tls_get_addr : 1; |
| |
| /* TRUE if symbol is defined as a protected symbol. */ |
| unsigned int def_protected : 1; |
| |
| /* 0: Symbol references are unknown. |
| 1: Symbol references aren't local. |
| 2: Symbol references are local. |
| */ |
| unsigned int local_ref : 2; |
| |
| /* TRUE if symbol is defined by linker. */ |
| unsigned int linker_def : 1; |
| |
| /* TRUE if symbol is referenced by R_386_GOTOFF relocation. This is |
| only used by i386. */ |
| unsigned int gotoff_ref : 1; |
| |
| /* TRUE if a weak symbol with a real definition needs a copy reloc. |
| When there is a weak symbol with a real definition, the processor |
| independent code will have arranged for us to see the real |
| definition first. We need to copy the needs_copy bit from the |
| real definition and check it when allowing copy reloc in PIE. This |
| is only used by x86-64. */ |
| unsigned int needs_copy : 1; |
| |
| /* Reference count of C/C++ function pointer relocations in read-write |
| section which can be resolved at run-time. */ |
| bfd_signed_vma func_pointer_refcount; |
| |
| /* Information about the GOT PLT entry. Filled when there are both |
| GOT and PLT relocations against the same function. */ |
| union gotplt_union plt_got; |
| |
| /* Information about the second PLT entry. */ |
| union gotplt_union plt_second; |
| |
| /* Offset of the GOTPLT entry reserved for the TLS descriptor, |
| starting at the end of the jump table. */ |
| bfd_vma tlsdesc_got; |
| }; |
| |
| struct elf_x86_lazy_plt_layout |
| { |
| /* The first entry in an absolute lazy procedure linkage table looks |
| like this. */ |
| const bfd_byte *plt0_entry; |
| unsigned int plt0_entry_size; /* Size of PLT0 entry. */ |
| |
| /* Later entries in an absolute lazy procedure linkage table look |
| like this. */ |
| const bfd_byte *plt_entry; |
| unsigned int plt_entry_size; /* Size of each PLT entry. */ |
| |
| /* Offsets into plt0_entry that are to be replaced with GOT[1] and |
| GOT[2]. */ |
| unsigned int plt0_got1_offset; |
| unsigned int plt0_got2_offset; |
| |
| /* Offset of the end of the PC-relative instruction containing |
| plt0_got2_offset. This is for x86-64 only. */ |
| unsigned int plt0_got2_insn_end; |
| |
| /* Offsets into plt_entry that are to be replaced with... */ |
| unsigned int plt_got_offset; /* ... address of this symbol in .got. */ |
| unsigned int plt_reloc_offset; /* ... offset into relocation table. */ |
| unsigned int plt_plt_offset; /* ... offset to start of .plt. */ |
| |
| /* Length of the PC-relative instruction containing plt_got_offset. |
| This is used for x86-64 only. */ |
| unsigned int plt_got_insn_size; |
| |
| /* Offset of the end of the PC-relative jump to plt0_entry. This is |
| used for x86-64 only. */ |
| unsigned int plt_plt_insn_end; |
| |
| /* Offset into plt_entry where the initial value of the GOT entry |
| points. */ |
| unsigned int plt_lazy_offset; |
| |
| /* The first entry in a PIC lazy procedure linkage table looks like |
| this. */ |
| const bfd_byte *pic_plt0_entry; |
| |
| /* Subsequent entries in a PIC lazy procedure linkage table look |
| like this. */ |
| const bfd_byte *pic_plt_entry; |
| |
| /* .eh_frame covering the lazy .plt section. */ |
| const bfd_byte *eh_frame_plt; |
| unsigned int eh_frame_plt_size; |
| }; |
| |
| struct elf_x86_non_lazy_plt_layout |
| { |
| /* Entries in an absolute non-lazy procedure linkage table look like |
| this. */ |
| const bfd_byte *plt_entry; |
| /* Entries in a PIC non-lazy procedure linkage table look like this. */ |
| const bfd_byte *pic_plt_entry; |
| |
| unsigned int plt_entry_size; /* Size of each PLT entry. */ |
| |
| /* Offsets into plt_entry that are to be replaced with... */ |
| unsigned int plt_got_offset; /* ... address of this symbol in .got. */ |
| |
| /* Length of the PC-relative instruction containing plt_got_offset. |
| This is used for x86-64 only. */ |
| unsigned int plt_got_insn_size; |
| |
| /* .eh_frame covering the non-lazy .plt section. */ |
| const bfd_byte *eh_frame_plt; |
| unsigned int eh_frame_plt_size; |
| }; |
| |
| struct elf_x86_plt_layout |
| { |
| /* The first entry in a lazy procedure linkage table looks like this. |
| This is only used for i386 where absolute PLT0 and PIC PLT0 are |
| different. */ |
| const bfd_byte *plt0_entry; |
| /* Entries in a procedure linkage table look like this. */ |
| const bfd_byte *plt_entry; |
| unsigned int plt_entry_size; /* Size of each PLT entry. */ |
| |
| /* 1 has PLT0. */ |
| unsigned int has_plt0; |
| |
| /* Offsets into plt_entry that are to be replaced with... */ |
| unsigned int plt_got_offset; /* ... address of this symbol in .got. */ |
| |
| /* Length of the PC-relative instruction containing plt_got_offset. |
| This is only used for x86-64. */ |
| unsigned int plt_got_insn_size; |
| |
| /* .eh_frame covering the .plt section. */ |
| const bfd_byte *eh_frame_plt; |
| unsigned int eh_frame_plt_size; |
| }; |
| |
| /* Values in tls_type of x86 ELF linker hash entry. */ |
| #define GOT_UNKNOWN 0 |
| #define GOT_NORMAL 1 |
| #define GOT_TLS_GD 2 |
| #define GOT_TLS_IE 4 |
| #define GOT_TLS_IE_POS 5 |
| #define GOT_TLS_IE_NEG 6 |
| #define GOT_TLS_IE_BOTH 7 |
| #define GOT_TLS_GDESC 8 |
| #define GOT_TLS_GD_BOTH_P(type) \ |
| ((type) == (GOT_TLS_GD | GOT_TLS_GDESC)) |
| #define GOT_TLS_GD_P(type) \ |
| ((type) == GOT_TLS_GD || GOT_TLS_GD_BOTH_P (type)) |
| #define GOT_TLS_GDESC_P(type) \ |
| ((type) == GOT_TLS_GDESC || GOT_TLS_GD_BOTH_P (type)) |
| #define GOT_TLS_GD_ANY_P(type) \ |
| (GOT_TLS_GD_P (type) || GOT_TLS_GDESC_P (type)) |
| |
| #define elf_x86_hash_entry(ent) \ |
| ((struct elf_x86_link_hash_entry *)(ent)) |
| |
| /* x86 ELF linker hash table. */ |
| |
| struct elf_x86_link_hash_table |
| { |
| struct elf_link_hash_table elf; |
| |
| /* Short-cuts to get to dynamic linker sections. */ |
| asection *interp; |
| asection *plt_eh_frame; |
| asection *plt_second; |
| asection *plt_second_eh_frame; |
| asection *plt_got; |
| asection *plt_got_eh_frame; |
| |
| /* Parameters describing PLT generation, lazy or non-lazy. */ |
| struct elf_x86_plt_layout plt; |
| |
| /* Parameters describing lazy PLT generation. */ |
| const struct elf_x86_lazy_plt_layout *lazy_plt; |
| |
| /* Parameters describing non-lazy PLT generation. */ |
| const struct elf_x86_non_lazy_plt_layout *non_lazy_plt; |
| |
| union |
| { |
| bfd_signed_vma refcount; |
| bfd_vma offset; |
| } tls_ld_or_ldm_got; |
| |
| /* The amount of space used by the jump slots in the GOT. */ |
| bfd_vma sgotplt_jump_table_size; |
| |
| /* Small local sym cache. */ |
| struct sym_cache sym_cache; |
| |
| /* _TLS_MODULE_BASE_ symbol. */ |
| struct bfd_link_hash_entry *tls_module_base; |
| |
| /* Used by local STT_GNU_IFUNC symbols. */ |
| htab_t loc_hash_table; |
| void * loc_hash_memory; |
| |
| /* The offset into sgot of the GOT entry used by the PLT entry |
| above. */ |
| bfd_vma tlsdesc_got; |
| |
| /* The index of the next R_X86_64_JUMP_SLOT entry in .rela.plt. */ |
| bfd_vma next_jump_slot_index; |
| /* The index of the next R_X86_64_IRELATIVE entry in .rela.plt. */ |
| bfd_vma next_irelative_index; |
| |
| /* TRUE if there are dynamic relocs against IFUNC symbols that apply |
| to read-only sections. */ |
| bfd_boolean readonly_dynrelocs_against_ifunc; |
| |
| /* TRUE if this is a VxWorks x86 target. This is only used for |
| i386. */ |
| bfd_boolean is_vxworks; |
| |
| /* The (unloaded but important) .rel.plt.unloaded section on VxWorks. |
| This is used for i386 only. */ |
| asection *srelplt2; |
| |
| /* The index of the next unused R_386_TLS_DESC slot in .rel.plt. This |
| is only used for i386. */ |
| bfd_vma next_tls_desc_index; |
| |
| /* The offset into splt of the PLT entry for the TLS descriptor |
| resolver. Special values are 0, if not necessary (or not found |
| to be necessary yet), and -1 if needed but not determined |
| yet. This is only used for x86-64. */ |
| bfd_vma tlsdesc_plt; |
| |
| bfd_vma (*r_info) (bfd_vma, bfd_vma); |
| bfd_vma (*r_sym) (bfd_vma); |
| bfd_boolean (*is_reloc_section) (const char *); |
| enum elf_target_id target_id; |
| unsigned int sizeof_reloc; |
| unsigned int dt_reloc; |
| unsigned int dt_reloc_sz; |
| unsigned int dt_reloc_ent; |
| unsigned int got_entry_size; |
| unsigned int pointer_r_type; |
| int dynamic_interpreter_size; |
| const char *dynamic_interpreter; |
| const char *tls_get_addr; |
| }; |
| |
| struct elf_x86_init_table |
| { |
| /* The lazy PLT layout. */ |
| const struct elf_x86_lazy_plt_layout *lazy_plt; |
| |
| /* The non-lazy PLT layout. */ |
| const struct elf_x86_non_lazy_plt_layout *non_lazy_plt; |
| |
| /* The lazy PLT layout for IBT. */ |
| const struct elf_x86_lazy_plt_layout *lazy_ibt_plt; |
| |
| /* The non-lazy PLT layout for IBT. */ |
| const struct elf_x86_non_lazy_plt_layout *non_lazy_ibt_plt; |
| |
| /* TRUE if this is a normal x86 target. */ |
| bfd_boolean normal_target; |
| |
| /* TRUE if this is a VxWorks x86 target. */ |
| bfd_boolean is_vxworks; |
| |
| bfd_vma (*r_info) (bfd_vma, bfd_vma); |
| bfd_vma (*r_sym) (bfd_vma); |
| }; |
| |
| struct elf_x86_obj_tdata |
| { |
| struct elf_obj_tdata root; |
| |
| /* tls_type for each local got entry. */ |
| char *local_got_tls_type; |
| |
| /* GOTPLT entries for TLS descriptors. */ |
| bfd_vma *local_tlsdesc_gotent; |
| }; |
| |
| enum elf_x86_plt_type |
| { |
| plt_non_lazy = 0, |
| plt_lazy = 1 << 0, |
| plt_pic = 1 << 1, |
| plt_second = 1 << 2, |
| plt_unknown = -1 |
| }; |
| |
| struct elf_x86_plt |
| { |
| const char *name; |
| asection *sec; |
| bfd_byte *contents; |
| enum elf_x86_plt_type type; |
| unsigned int plt_got_offset; |
| unsigned int plt_entry_size; |
| unsigned int plt_got_insn_size; /* Only used for x86-64. */ |
| long count; |
| }; |
| |
| #define elf_x86_tdata(abfd) \ |
| ((struct elf_x86_obj_tdata *) (abfd)->tdata.any) |
| |
| #define elf_x86_local_got_tls_type(abfd) \ |
| (elf_x86_tdata (abfd)->local_got_tls_type) |
| |
| #define elf_x86_local_tlsdesc_gotent(abfd) \ |
| (elf_x86_tdata (abfd)->local_tlsdesc_gotent) |
| |
| #define elf_x86_compute_jump_table_size(htab) \ |
| ((htab)->elf.srelplt->reloc_count * (htab)->got_entry_size) |
| |
| #define is_x86_elf(bfd, htab) \ |
| (bfd_get_flavour (bfd) == bfd_target_elf_flavour \ |
| && elf_tdata (bfd) != NULL \ |
| && elf_object_id (bfd) == (htab)->target_id) |
| |
| extern bfd_boolean _bfd_x86_elf_mkobject |
| (bfd *); |
| |
| extern void _bfd_x86_elf_set_tls_module_base |
| (struct bfd_link_info *); |
| |
| extern bfd_vma _bfd_x86_elf_dtpoff_base |
| (struct bfd_link_info *); |
| |
| extern bfd_boolean _bfd_x86_elf_readonly_dynrelocs |
| (struct elf_link_hash_entry *, void *); |
| |
| extern struct elf_link_hash_entry * _bfd_elf_x86_get_local_sym_hash |
| (struct elf_x86_link_hash_table *, bfd *, const Elf_Internal_Rela *, |
| bfd_boolean); |
| |
| extern hashval_t _bfd_x86_elf_local_htab_hash |
| (const void *); |
| |
| extern int _bfd_x86_elf_local_htab_eq |
| (const void *, const void *); |
| |
| extern struct bfd_hash_entry * _bfd_x86_elf_link_hash_newfunc |
| (struct bfd_hash_entry *, struct bfd_hash_table *, const char *); |
| |
| extern struct bfd_link_hash_table * _bfd_x86_elf_link_hash_table_create |
| (bfd *); |
| |
| extern int _bfd_x86_elf_compare_relocs |
| (const void *, const void *); |
| |
| extern bfd_boolean _bfd_x86_elf_link_check_relocs |
| (bfd *, struct bfd_link_info *); |
| |
| extern bfd_boolean _bfd_x86_elf_size_dynamic_sections |
| (bfd *, struct bfd_link_info *); |
| |
| extern bfd_boolean _bfd_x86_elf_always_size_sections |
| (bfd *, struct bfd_link_info *); |
| |
| extern void _bfd_x86_elf_merge_symbol_attribute |
| (struct elf_link_hash_entry *, const Elf_Internal_Sym *, |
| bfd_boolean, bfd_boolean); |
| |
| extern void _bfd_x86_elf_copy_indirect_symbol |
| (struct bfd_link_info *, struct elf_link_hash_entry *, |
| struct elf_link_hash_entry *); |
| |
| extern bfd_boolean _bfd_x86_elf_fixup_symbol |
| (struct bfd_link_info *, struct elf_link_hash_entry *); |
| |
| extern bfd_boolean _bfd_x86_elf_hash_symbol |
| (struct elf_link_hash_entry *); |
| |
| extern bfd_boolean _bfd_x86_elf_adjust_dynamic_symbol |
| (struct bfd_link_info *, struct elf_link_hash_entry *); |
| |
| extern bfd_boolean _bfd_x86_elf_link_symbol_references_local |
| (struct bfd_link_info *, struct elf_link_hash_entry *); |
| |
| extern asection * _bfd_x86_elf_gc_mark_hook |
| (asection *, struct bfd_link_info *, Elf_Internal_Rela *, |
| struct elf_link_hash_entry *, Elf_Internal_Sym *); |
| |
| extern long _bfd_x86_elf_get_synthetic_symtab |
| (bfd *, long, long, bfd_vma, struct elf_x86_plt [], asymbol **, |
| asymbol **); |
| |
| extern enum elf_property_kind _bfd_x86_elf_parse_gnu_properties |
| (bfd *, unsigned int, bfd_byte *, unsigned int); |
| |
| extern bfd_boolean _bfd_x86_elf_merge_gnu_properties |
| (struct bfd_link_info *, bfd *, elf_property *, elf_property *); |
| |
| extern bfd * _bfd_x86_elf_link_setup_gnu_properties |
| (struct bfd_link_info *, struct elf_x86_init_table *); |
| |
| #define bfd_elf64_mkobject \ |
| _bfd_x86_elf_mkobject |
| #define bfd_elf32_mkobject \ |
| _bfd_x86_elf_mkobject |
| #define bfd_elf64_bfd_link_hash_table_create \ |
| _bfd_x86_elf_link_hash_table_create |
| #define bfd_elf32_bfd_link_hash_table_create \ |
| _bfd_x86_elf_link_hash_table_create |
| #define bfd_elf64_bfd_link_check_relocs \ |
| _bfd_x86_elf_link_check_relocs |
| #define bfd_elf32_bfd_link_check_relocs \ |
| _bfd_x86_elf_link_check_relocs |
| |
| #define elf_backend_size_dynamic_sections \ |
| _bfd_x86_elf_size_dynamic_sections |
| #define elf_backend_always_size_sections \ |
| _bfd_x86_elf_always_size_sections |
| #define elf_backend_merge_symbol_attribute \ |
| _bfd_x86_elf_merge_symbol_attribute |
| #define elf_backend_copy_indirect_symbol \ |
| _bfd_x86_elf_copy_indirect_symbol |
| #define elf_backend_fixup_symbol \ |
| _bfd_x86_elf_fixup_symbol |
| #define elf_backend_hash_symbol \ |
| _bfd_x86_elf_hash_symbol |
| #define elf_backend_adjust_dynamic_symbol \ |
| _bfd_x86_elf_adjust_dynamic_symbol |
| #define elf_backend_gc_mark_hook \ |
| _bfd_x86_elf_gc_mark_hook |
| #define elf_backend_omit_section_dynsym \ |
| ((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true) |
| #define elf_backend_parse_gnu_properties \ |
| _bfd_x86_elf_parse_gnu_properties |
| #define elf_backend_merge_gnu_properties \ |
| _bfd_x86_elf_merge_gnu_properties |