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glibc/sysdeps/unix/sysv/linux/x86_64/pointer_guard.h
2025-10-12 17:59:16 +02:00

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2.6 KiB
C

/* Pointer obfuscation implenentation. x86-64 version.
Copyright (C) 2005-2025 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/>. */
#ifndef POINTER_GUARD_H
#define POINTER_GUARD_H
#include <x86-lp_size.h>
#include <tcb-offsets.h>
#if IS_IN (rtld)
/* We cannot use the thread descriptor because in ld.so we use setjmp
earlier than the descriptor is initialized. */
# ifdef __ASSEMBLER__
# define PTR_MANGLE(reg) xor __pointer_chk_guard_local(%rip), reg; \
rol $2*LP_SIZE+1, reg
# define PTR_DEMANGLE(reg) ror $2*LP_SIZE+1, reg; \
xor __pointer_chk_guard_local(%rip), reg
# else
# include <stdint.h>
extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
# define PTR_MANGLE(var) \
do { \
(var) = (__typeof (var)) ((uintptr_t) (var) \
^ __pointer_chk_guard_local); \
asm ("rol $2*" LP_SIZE "+1, %0" : "+r" (var)); \
} while (0)
# define PTR_DEMANGLE(var) \
do { \
asm ("ror $2*" LP_SIZE "+1, %0" : "+r" (var)); \
(var) = (__typeof (var)) ((uintptr_t) (var) \
^ __pointer_chk_guard_local); \
} while (0)
# endif
#else
# ifdef __ASSEMBLER__
# define PTR_MANGLE(reg) xor %fs:POINTER_GUARD, reg; \
rol $2*LP_SIZE+1, reg
# define PTR_DEMANGLE(reg) ror $2*LP_SIZE+1, reg; \
xor %fs:POINTER_GUARD, reg
# else
# include <tls.h>
# define PTR_MANGLE(var) \
do { \
(var) = (__typeof (var)) ((uintptr_t) (var) \
^ ((tcbhead_t __seg_fs *)0)->pointer_guard); \
asm ("rol $2*" LP_SIZE "+1, %0" : "+r" (var)); \
} while (0)
# define PTR_DEMANGLE(var) \
do { \
asm ("ror $2*" LP_SIZE "+1, %0" : "+r" (var)); \
(var) = (__typeof (var)) ((uintptr_t) (var) \
^ ((tcbhead_t __seg_fs *)0)->pointer_guard); \
} while (0)
# endif
#endif
#endif /* POINTER_GUARD_H */