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| author | Fangrui Song <maskray@google.com> | 2022-05-23 13:37:05 -0700 |
|---|---|---|
| committer | Fangrui Song <maskray@google.com> | 2022-05-23 13:37:05 -0700 |
| commit | e555954e026df1b85b8ef6c101d05f97b1520d7e (patch) | |
| tree | 798159309b7d8a8dbed27f7e40fb999d6fa6b0cd | |
| parent | a8b11bd1f8dc68795b377138b5d94638ef75a50d (diff) | |
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Revert "[AArch64][BZ #17711] Fix extern protected data handling"
This reverts commit 0910702c4d2cf9e8302b35c9519548726e1ac489.
Say both a.so and b.so define protected data symbol `var` and the executable
copy relocates var. ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA has strange
semantics: a.so accesses the copy in the executable while b.so accesses its
own. This behavior requires that (a) the compiler emits GOT-generating
relocations (b) the linker produces GLOB_DAT instead of RELATIVE.
Without the ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA code, b.so's GLOB_DAT
will bind to the executable (normal behavior).
For aarch64 it makes sense to restore the original behavior and don't
pay the ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA cost. The behavior is very
unlikely used by anyone.
* Clang code generator treats STV_PROTECTED the same way as STV_HIDDEN:
no GOT-generating relocation in the first place.
* gold and lld reject copy relocation on a STV_PROTECTED symbol.
* Nowadays -fpie/-fpic modes are popular. GCC/Clang's codegen uses
GOT-generating relocation when accessing an default visibility
external symbol which avoids copy relocation.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
| -rw-r--r-- | sysdeps/aarch64/dl-machine.h | 13 | ||||
| -rw-r--r-- | sysdeps/aarch64/dl-sysdep.h | 21 |
2 files changed, 6 insertions, 28 deletions
diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h index fe120bb507..292abe5152 100644 --- a/sysdeps/aarch64/dl-machine.h +++ b/sysdeps/aarch64/dl-machine.h @@ -109,13 +109,12 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[], #define RTLD_START asm (".globl _dl_start"); #define elf_machine_type_class(type) \ - ((((type) == AARCH64_R(JUMP_SLOT) \ - || (type) == AARCH64_R(TLS_DTPMOD) \ - || (type) == AARCH64_R(TLS_DTPREL) \ - || (type) == AARCH64_R(TLS_TPREL) \ - || (type) == AARCH64_R(TLSDESC)) * ELF_RTYPE_CLASS_PLT) \ - | (((type) == AARCH64_R(COPY)) * ELF_RTYPE_CLASS_COPY) \ - | (((type) == AARCH64_R(GLOB_DAT)) * ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA)) + ((((type) == R_AARCH64_JUMP_SLOT || \ + (type) == R_AARCH64_TLS_DTPMOD || \ + (type) == R_AARCH64_TLS_DTPREL || \ + (type) == R_AARCH64_TLS_TPREL || \ + (type) == R_AARCH64_TLSDESC) * ELF_RTYPE_CLASS_PLT) \ + | (((type) == R_AARCH64_COPY) * ELF_RTYPE_CLASS_COPY)) #define ELF_MACHINE_JMP_SLOT AARCH64_R(JUMP_SLOT) diff --git a/sysdeps/aarch64/dl-sysdep.h b/sysdeps/aarch64/dl-sysdep.h deleted file mode 100644 index 1516dd7d3f..0000000000 --- a/sysdeps/aarch64/dl-sysdep.h +++ /dev/null @@ -1,21 +0,0 @@ -/* Copyright (C) 2002-2022 Free Software Foundation, Inc. - - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public License as - published by the Free Software Foundation; either version 2.1 of the - License, or (at your option) any later version. - - The GNU C Library 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 - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - <https://www.gnu.org/licenses/>. */ - -#include_next <dl-sysdep.h> - -#define DL_EXTERN_PROTECTED_DATA |