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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.
59 lines
1.6 KiB
Bash
59 lines
1.6 KiB
Bash
source_sh ${srcdir}/emulparams/plt_unwind.sh
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source_sh ${srcdir}/emulparams/extern_protected_data.sh
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source_sh ${srcdir}/emulparams/dynamic_undefined_weak.sh
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source_sh ${srcdir}/emulparams/reloc_overflow.sh
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source_sh ${srcdir}/emulparams/call_nop.sh
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source_sh ${srcdir}/emulparams/cet.sh
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source_sh ${srcdir}/emulparams/x86-report-relative.sh
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source_sh ${srcdir}/emulparams/x86-64-level.sh
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source_sh ${srcdir}/emulparams/x86-64-lam.sh
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source_sh ${srcdir}/emulparams/x86-64-plt.sh
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source_sh ${srcdir}/emulparams/static.sh
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source_sh ${srcdir}/emulparams/dt-relr.sh
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SCRIPT_NAME=elf
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ELFSIZE=64
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OUTPUT_FORMAT="elf64-x86-64"
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NO_REL_RELOCS=yes
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TEXT_START_ADDR=0x400000
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MAXPAGESIZE="CONSTANT (MAXPAGESIZE)"
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COMMONPAGESIZE="CONSTANT (COMMONPAGESIZE)"
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ARCH="i386:x86-64"
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MACHINE=
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TEMPLATE_NAME=elf
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EXTRA_EM_FILE="elf-x86"
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GENERATE_SHLIB_SCRIPT=yes
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GENERATE_PIE_SCRIPT=yes
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NO_SMALL_DATA=yes
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LARGE_SECTIONS=yes
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LARGE_BSS_AFTER_BSS=
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SEPARATE_GOTPLT="SIZEOF (.got.plt) >= 24 ? 24 : 0"
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IREL_IN_PLT=
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# These sections are placed right after .plt section.
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OTHER_PLT_SECTIONS="
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.plt.got ${RELOCATING-0} : { *(.plt.got) }
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.plt.sec ${RELOCATING-0} : { *(.plt.sec) }
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"
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if [ "x${host}" = "x${target}" ]; then
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case " $EMULATION_LIBPATH " in
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*" ${EMULATION_NAME} "*)
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NATIVE=yes
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esac
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fi
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# Linux/Solaris modify the default library search path to first include
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# a 64-bit specific directory.
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case "$target" in
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x86_64*-linux*|i[3-7]86-*-linux-*)
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case "$EMULATION_NAME" in
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*64*)
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LIBPATH_SUFFIX=64
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;;
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esac
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;;
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*-*-solaris2*)
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LIBPATH_SUFFIX=/amd64
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ELF_INTERPRETER_NAME=\"/lib/amd64/ld.so.1\"
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;;
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esac
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