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| author | H.J. Lu <hjl.tools@gmail.com> | 2018-03-25 05:02:17 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2018-03-25 05:02:32 -0700 |
| commit | bf54968b128a2133174d81c438d402ecfaf83042 (patch) | |
| tree | fadfbd0205867e75b54346add9cb3e22eef3df4b /bfd/elf64-x86-64.c | |
| parent | b3ee71e749f3c93c51cd6fb3fed51ffd54243117 (diff) | |
| download | gdb-bf54968b128a2133174d81c438d402ecfaf83042.zip gdb-bf54968b128a2133174d81c438d402ecfaf83042.tar.gz gdb-bf54968b128a2133174d81c438d402ecfaf83042.tar.bz2 | |
x86-64: Add ENDBR64 to the TLSDESC PLT entry
The TLSDESC entry in a lazy procedure linkage table is called indirectly
with "callq *(%rax)". This patch adds an ENDBR64 to support indirect
branch tracking in Intel CET. The TLSDESC PLT entry now looks like:
0xf3, 0x0f, 0x1e, 0xfa, /* endbr64 */
0xff, 0x35, 8, 0, 0, 0, /* pushq GOT+8(%rip) */
0xff, 0x25, 16, 0, 0, 0 /* jmpq *GOT+TDG(%rip) */
The BND prefix isn't needed since MPX isn't used for TLSDESC.
bfd/
PR ld/23000
* elf64-x86-64.c (elf_x86_64_finish_dynamic_sections): Add
ENDBR64 to the TLSDESC PLT entry.
ld/
PR ld/23000
* testsuite/ld-x86-64/tlsdesc.pd: Updated.
Diffstat (limited to 'bfd/elf64-x86-64.c')
| -rw-r--r-- | bfd/elf64-x86-64.c | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c index a964316..fcc8236 100644 --- a/bfd/elf64-x86-64.c +++ b/bfd/elf64-x86-64.c @@ -4411,15 +4411,23 @@ elf_x86_64_finish_dynamic_sections (bfd *output_bfd, if (htab->tlsdesc_plt) { + /* The TLSDESC entry in a lazy procedure linkage table. */ + static const bfd_byte tlsdesc_plt_entry[LAZY_PLT_ENTRY_SIZE] = + { + 0xf3, 0x0f, 0x1e, 0xfa, /* endbr64 */ + 0xff, 0x35, 8, 0, 0, 0, /* pushq GOT+8(%rip) */ + 0xff, 0x25, 16, 0, 0, 0 /* jmpq *GOT+TDG(%rip) */ + }; + bfd_put_64 (output_bfd, (bfd_vma) 0, htab->elf.sgot->contents + htab->tlsdesc_got); memcpy (htab->elf.splt->contents + htab->tlsdesc_plt, - htab->lazy_plt->plt0_entry, - htab->lazy_plt->plt0_entry_size); + tlsdesc_plt_entry, LAZY_PLT_ENTRY_SIZE); - /* Add offset for pushq GOT+8(%rip), since the - instruction uses 6 bytes subtract this value. */ + /* Add offset for pushq GOT+8(%rip), since ENDBR64 uses 4 + bytes and the instruction uses 6 bytes, subtract these + values. */ bfd_put_32 (output_bfd, (htab->elf.sgotplt->output_section->vma + htab->elf.sgotplt->output_offset @@ -4427,14 +4435,13 @@ elf_x86_64_finish_dynamic_sections (bfd *output_bfd, - htab->elf.splt->output_section->vma - htab->elf.splt->output_offset - htab->tlsdesc_plt - - 6), + - 4 - 6), (htab->elf.splt->contents + htab->tlsdesc_plt - + htab->lazy_plt->plt0_got1_offset)); - /* Add offset for the PC-relative instruction accessing - GOT+TDG, where TDG stands for htab->tlsdesc_got, - subtracting the offset to the end of that - instruction. */ + + 4 + 2)); + /* Add offset for indirect branch via GOT+TDG, where TDG + stands for htab->tlsdesc_got, subtracting the offset + to the end of that instruction. */ bfd_put_32 (output_bfd, (htab->elf.sgot->output_section->vma + htab->elf.sgot->output_offset @@ -4442,10 +4449,9 @@ elf_x86_64_finish_dynamic_sections (bfd *output_bfd, - htab->elf.splt->output_section->vma - htab->elf.splt->output_offset - htab->tlsdesc_plt - - htab->lazy_plt->plt0_got2_insn_end), + - 4 - 6 - 6), (htab->elf.splt->contents - + htab->tlsdesc_plt - + htab->lazy_plt->plt0_got2_offset)); + + htab->tlsdesc_plt + 4 + 6 + 2)); } } |