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glibc/sysdeps/unix/sysv/linux/alpha/pointer_guard.h

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Introduce <pointer_guard.h>, extracted from <sysdep.h> 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>
2022-10-18 15:00:07 +00:00
/* Pointer guard implementation. Alpha version.
Update copyright dates with scripts/update-copyrights
2023-01-06 21:08:04 +00:00
Copyright (C) 2006-2023 Free Software Foundation, Inc.
Introduce <pointer_guard.h>, extracted from <sysdep.h> 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>
2022-10-18 15:00:07 +00:00
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/>. */
#ifndef POINTER_GUARD_H
#define POINTER_GUARD_H
/* Pointer mangling support. Note that tls access is slow enough that
we don't deoptimize things by placing the pointer check value there. */
#ifdef __ASSEMBLER__
# if IS_IN (rtld)
# define PTR_MANGLE(dst, src, tmp) \
ldah tmp, __pointer_chk_guard_local($29) !gprelhigh; \
ldq tmp, __pointer_chk_guard_local(tmp) !gprellow; \
xor src, tmp, dst
# define PTR_MANGLE2(dst, src, tmp) \
xor src, tmp, dst
# elif defined SHARED
# define PTR_MANGLE(dst, src, tmp) \
ldq tmp, __pointer_chk_guard; \
xor src, tmp, dst
# else
# define PTR_MANGLE(dst, src, tmp) \
ldq tmp, __pointer_chk_guard_local; \
xor src, tmp, dst
# endif
# define PTR_MANGLE2(dst, src, tmp) \
xor src, tmp, dst
# define PTR_DEMANGLE(dst, tmp) PTR_MANGLE(dst, dst, tmp)
# define PTR_DEMANGLE2(dst, tmp) PTR_MANGLE2(dst, dst, tmp)
#else
# include <stdint.h>
# if (IS_IN (rtld) \
|| (!defined SHARED && (IS_IN (libc) \
|| IS_IN (libpthread))))
extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
# define PTR_MANGLE(var) \
(var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
# else
extern uintptr_t __pointer_chk_guard attribute_relro;
# define PTR_MANGLE(var) \
(var) = (__typeof(var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
# endif
# define PTR_DEMANGLE(var) PTR_MANGLE(var)
#endif /* ASSEMBLER */
#endif /* POINTER_GUARD_H */
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