sysdeps/unix/sysv/linux/x86_64/x32/arch_prctl.c

   1 /* arch_prctl call for Linux/x32.
   2    Copyright (C) 2012-2013 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sys/prctl.h>
  21 #include <sys/syscall.h>
  22 #include <sysdep.h>
  23
  24 /* Since x32 arch_prctl stores 32-bit base address of segment registers
  25    %fs and %gs as unsigned 64-bit value via ARCH_GET_FS and ARCH_GET_GS,
  26    we use an unsigned 64-bit variable to hold the base address and copy
  27    it to ADDR after the system call returns.  */
  28
  29 int
  30 __arch_prctl (int code, uintptr_t *addr)
  31 {
  32   int res;
  33   uint64_t addr64;
  34   void *prctl_arg = addr;
  35
  36   switch (code)
  37     {
  38     case ARCH_GET_FS:
  39     case ARCH_GET_GS:
  40       prctl_arg = &addr64;
  41       break;
  42     }
  43
  44   res = INLINE_SYSCALL (arch_prctl, 2, code, prctl_arg);
  45   if (res == 0)
  46     switch (code)
  47       {
  48       case ARCH_GET_FS:
  49       case ARCH_GET_GS:
  50          /* Check for a large value that overflows.  */
  51         if ((uintptr_t) addr64 != addr64)
  52           {
  53             __set_errno (EOVERFLOW);
  54             return -1;
  55           }
  56         *addr = (uintptr_t) addr64;
  57         break;
  58       }
  59
  60   return res;
  61 }
  62 weak_alias (__arch_prctl, arch_prctl)