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88f4b6929c
This allows us to define a generic no-op version of PTR_MANGLE and PTR_DEMANGLE. In the future, we can use PTR_MANGLE and PTR_DEMANGLE unconditionally in C sources, avoiding an unintended loss of hardening due to missing include files or unlucky header inclusion ordering. In i386 and x86_64, we can avoid a <tls.h> dependency in the C code by using the computed constant from <tcb-offsets.h>. <sysdep.h> no longer includes these definitions, so there is no cyclic dependency anymore when computing the <tcb-offsets.h> constants. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
63 lines
2.4 KiB
C
63 lines
2.4 KiB
C
/* Pointer guard implementation. Alpha version.
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Copyright (C) 2006-2022 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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#ifndef POINTER_GUARD_H
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#define POINTER_GUARD_H
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/* Pointer mangling support. Note that tls access is slow enough that
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we don't deoptimize things by placing the pointer check value there. */
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#ifdef __ASSEMBLER__
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# if IS_IN (rtld)
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# define PTR_MANGLE(dst, src, tmp) \
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ldah tmp, __pointer_chk_guard_local($29) !gprelhigh; \
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ldq tmp, __pointer_chk_guard_local(tmp) !gprellow; \
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xor src, tmp, dst
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# define PTR_MANGLE2(dst, src, tmp) \
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xor src, tmp, dst
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# elif defined SHARED
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# define PTR_MANGLE(dst, src, tmp) \
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ldq tmp, __pointer_chk_guard; \
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xor src, tmp, dst
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# else
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# define PTR_MANGLE(dst, src, tmp) \
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ldq tmp, __pointer_chk_guard_local; \
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xor src, tmp, dst
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# endif
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# define PTR_MANGLE2(dst, src, tmp) \
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xor src, tmp, dst
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# define PTR_DEMANGLE(dst, tmp) PTR_MANGLE(dst, dst, tmp)
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# define PTR_DEMANGLE2(dst, tmp) PTR_MANGLE2(dst, dst, tmp)
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#else
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# include <stdint.h>
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# if (IS_IN (rtld) \
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|| (!defined SHARED && (IS_IN (libc) \
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|| IS_IN (libpthread))))
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extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
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# define PTR_MANGLE(var) \
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(var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
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# else
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extern uintptr_t __pointer_chk_guard attribute_relro;
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# define PTR_MANGLE(var) \
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(var) = (__typeof(var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
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# endif
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# define PTR_DEMANGLE(var) PTR_MANGLE(var)
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#endif /* ASSEMBLER */
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#endif /* POINTER_GUARD_H */
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