1  /* Pointer obfuscation implenentation.  i386 version.
       2     Copyright (C) 2005-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef POINTER_GUARD_H
      20  #define POINTER_GUARD_H
      21  
      22  #include <tcb-offsets.h>
      23  
      24  #if IS_IN (rtld)
      25  /* We cannot use the thread descriptor because in ld.so we use setjmp
      26     earlier than the descriptor is initialized.  Using a global variable
      27     is too complicated here since we have no PC-relative addressing mode.  */
      28  # include <sysdeps/generic/pointer_guard.h>
      29  #else
      30  # ifdef __ASSEMBLER__
      31  #  define PTR_MANGLE(reg)       xorl %gs:POINTER_GUARD, reg;                  \
      32                                  roll $9, reg
      33  #  define PTR_DEMANGLE(reg)     rorl $9, reg;                                 \
      34                                  xorl %gs:POINTER_GUARD, reg
      35  # else
      36  #  define PTR_MANGLE(var)       asm ("xorl %%gs:%c2, %0\n"                    \
      37                                       "roll $9, %0"                            \
      38                                       : "=r" (var)                             \
      39                                       : "0" (var),                             \
      40                                         "i" (POINTER_GUARD))
      41  #  define PTR_DEMANGLE(var)     asm ("rorl $9, %0\n"                          \
      42                                       "xorl %%gs:%c2, %0"                      \
      43                                       : "=r" (var)                             \
      44                                       : "0" (var),                             \
      45                                         "i" (POINTER_GUARD))
      46  # endif
      47  #endif
      48  
      49  #endif /* POINTER_GUARD_H */