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>

diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
index fe120bb..292abe5 100644 (file)
--- 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 (file)
index 1516dd7..0000000
--- 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