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ea85e7d550
The changes in commit a93d9e03a3
("Extend struct r_debug to support multiple namespaces [BZ #15971]")
break the dyninst dynamic instrumentation tool. It brings its
own definition of _r_debug (rather than a declaration).
Furthermore, it turns out it is rather hard to use the proposed
handshake for accessing _r_debug via DT_DEBUG. If applications want
to access _r_debug, they can do so directly if the relevant code has
been built as PIC. To protect against harm from accidental copy
relocations due to linker relaxations, this commit restores copy
relocation support by adjusting both copies if interposition or
copy relocations are in play. Therefore, it is possible to
use a hidden reference in ld.so to access _r_debug.
Only perform the copy relocation initialization if libc has been
loaded. Otherwise, the ld.so search scope can be empty, and the
lookup of the _r_debug symbol mail fail.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
42 lines
1.4 KiB
ArmAsm
42 lines
1.4 KiB
ArmAsm
/* Define symbols used to communicate dynamic linker state to the
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debugger at runtime.
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Copyright (C) 2021-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <rtld-sizes.h>
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#include <sysdep.h>
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/* Some targets define a macro to denote the zero register. */
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#undef zero
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/* Define 2 symbols, _r_debug_extended and _r_debug, which is an alias
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of _r_debug_extended, but with the size of struct r_debug. */
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.globl _r_debug
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.type _r_debug, %object
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.size _r_debug, R_DEBUG_SIZE
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.hidden _r_debug_extended
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.globl _r_debug_extended
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.type _r_debug_extended, %object
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.size _r_debug_extended, R_DEBUG_EXTENDED_SIZE
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.section .bss
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.balign R_DEBUG_EXTENDED_ALIGN
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_r_debug:
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_r_debug_extended:
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.zero R_DEBUG_EXTENDED_SIZE
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rtld_hidden_def (_r_debug)
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