sysdeps/unix/sysv/linux/x86/arch-pkey.h

   1 /* Helper functions for manipulating memory protection keys.
   2    Copyright (C) 2017-2019 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 _ARCH_PKEY_H
  20 #define _ARCH_PKEY_H
  21
  22 /* Return the value of the PKRU register.  */
  23 static inline unsigned int
  24 pkey_read (void)
  25 {
  26   unsigned int result;
  27   __asm__ volatile (".byte 0x0f, 0x01, 0xee"
  28                     : "=a" (result) : "c" (0) : "rdx");
  29   return result;
  30 }
  31
  32 /* Overwrite the PKRU register with VALUE.  */
  33 static inline void
  34 pkey_write (unsigned int value)
  35 {
  36   __asm__ volatile (".byte 0x0f, 0x01, 0xef"
  37                     : : "a" (value), "c" (0), "d" (0));
  38 }
  39
  40 #endif /* _ARCH_PKEY_H */