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832ca732b8
The PLT entry in executables and shared libraries contains an indirect
branch, like
jmp *foo@GOTPCREL(%rip)
push $index_foo
jmp .PLT0
or
endbr64
jmp *foo@GOTPCREL(%rip)
NOP padding
which is used to branch to the function, foo, defined in another object.
Each R_X86_64_JUMP_SLOT relocation has a corresponding PLT entry.
The dynamic tags have been added to the x86-64 psABI to mark such PLT
entries:
6d824a52a4
Add an x86-64 linker option, -z mark-plt, to mark PLT entries with
#define DT_X86_64_PLT (DT_LOPROC + 0)
#define DT_X86_64_PLTSZ (DT_LOPROC + 1)
#define DT_X86_64_PLTENT (DT_LOPROC + 3)
1. DT_X86_64_PLT: The address of the procedure linkage table.
2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage
table.
3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table
entry.
and set the r_addend field of the R_X86_64_JUMP_SLOT relocation to the
memory offset of the indirect branch instruction. The dynamic linker
can use these tags to update the PLT section to direct branch.
bfd/
* elf-linker-x86.h (elf_linker_x86_params): Add mark_plt.
* elf64-x86-64.c (elf_x86_64_finish_dynamic_symbol): Set the
r_addend of R_X86_64_JUMP_SLOT to the indirect branch offset
in PLT entry for -z mark-plt.
* elfxx-x86.c (_bfd_x86_elf_size_dynamic_sections): Add
DT_X86_64_PLT, DT_X86_64_PLTSZ and DT_X86_64_PLTENT for
-z mark-plt.
(_bfd_x86_elf_finish_dynamic_sections): Set DT_X86_64_PLT,
DT_X86_64_PLTSZ and DT_X86_64_PLTENT.
(_bfd_x86_elf_get_synthetic_symtab): Ignore addend for
JUMP_SLOT relocation.
(_bfd_x86_elf_link_setup_gnu_properties): Set
plt_indirect_branch_offset.
* elfxx-x86.h (elf_x86_plt_layout): Add plt_indirect_branch_offset.
binutils/
* readelf.c (get_x86_64_dynamic_type): New function.
(get_dynamic_type): Call get_x86_64_dynamic_type.
include/
* elf/x86-64.h (DT_X86_64_PLT): New.
(DT_X86_64_PLTSZ): Likewise.
(DT_X86_64_PLTENT): Likewise.
ld/
* ld.texi: Document -z mark-plt and -z nomark-plt.
* emulparams/elf32_x86_64.sh: Source x86-64-plt.sh.
* emulparams/elf_x86_64.sh: Likewise.
* emulparams/x86-64-plt.sh: New file.
* testsuite/ld-x86-64/mark-plt-1.s: Likewise.
* testsuite/ld-x86-64/mark-plt-1a-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1a.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1b-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1b.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1c-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1c.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1d-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1d.d: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run -z mark-plt tests.
85 lines
2.9 KiB
C
85 lines
2.9 KiB
C
/* x86-specific ELF linker support between ld and bfd.
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Copyright (C) 2019-2023 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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/* Missing IBT, SHSTK and LAM property report control. */
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enum elf_x86_prop_report
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{
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prop_report_none = 0, /* Do nothing. */
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prop_report_warning = 1 << 0, /* Issue a warning. */
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prop_report_error = 1 << 1, /* Issue an error. */
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prop_report_ibt = 1 << 2, /* Report missing IBT property. */
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prop_report_shstk = 1 << 3 /* Report missing SHSTK property. */
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};
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/* Used to pass x86-specific linker options from ld to bfd. */
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struct elf_linker_x86_params
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{
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/* TRUE if IBT-enabled PLT entries should be generated. */
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unsigned int ibtplt: 1;
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/* TRUE if GNU_PROPERTY_X86_FEATURE_1_IBT should be generated. */
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unsigned int ibt: 1;
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/* TRUE if GNU_PROPERTY_X86_FEATURE_1_SHSTK should be generated. */
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unsigned int shstk: 1;
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/* TRUE if GNU_PROPERTY_X86_FEATURE_1_LAM_U48 should be generated. */
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unsigned int lam_u48: 1;
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/* TRUE if GNU_PROPERTY_X86_FEATURE_1_LAM_U57 should be generated. */
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unsigned int lam_u57: 1;
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/* TRUE if we shouldn't check relocation overflow. */
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unsigned int no_reloc_overflow_check: 1;
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/* TRUE if generate a 1-byte NOP as suffix for x86 call instruction. */
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unsigned int call_nop_as_suffix : 1;
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/* TRUE if -static is passed at command-line before all input files. */
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unsigned int static_before_all_inputs : 1;
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/* TRUE if --dynamic-linker is passed at command-line. */
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unsigned int has_dynamic_linker : 1;
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/* Report relative relocations. */
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unsigned int report_relative_reloc : 1;
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/* Mark PLT with dynamic tags. */
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unsigned int mark_plt : 1;
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/* X86-64 ISA level needed. */
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unsigned int isa_level;
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/* Report missing IBT and SHSTK properties. */
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enum elf_x86_prop_report cet_report;
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/* Report missing LAM_U48 property. */
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enum elf_x86_prop_report lam_u48_report;
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/* Report missing LAM_U57 property. */
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enum elf_x86_prop_report lam_u57_report;
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/* The 1-byte NOP for x86 call instruction. */
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char call_nop_byte;
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};
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extern void _bfd_elf_linker_x86_set_options
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(struct bfd_link_info *, struct elf_linker_x86_params *);
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