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

   1 /* arch_prctl call for Linux/x32.
   2    Copyright (C) 2012-2014 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 #include <stdint.h>
  24
  25 /* Since x32 arch_prctl stores 32-bit base address of segment registers
  26    %fs and %gs as unsigned 64-bit value via ARCH_GET_FS and ARCH_GET_GS,
  27    we use an unsigned 64-bit variable to hold the base address and copy
  28    it to ADDR after the system call returns.  */
  29
  30 int
  31 __arch_prctl (int code, uintptr_t *addr)
  32 {
  33   int res;
  34   uint64_t addr64;
  35   void *prctl_arg = addr;
  36
  37   switch (code)
  38     {
  39     case ARCH_GET_FS:
  40     case ARCH_GET_GS:
  41       prctl_arg = &addr64;
  42       break;
  43     }
  44
  45   res = INLINE_SYSCALL (arch_prctl, 2, code, prctl_arg);
  46   if (res == 0)
  47     switch (code)
  48       {
  49       case ARCH_GET_FS:
  50       case ARCH_GET_GS:
  51          /* Check for a large value that overflows.  */
  52         if ((uintptr_t) addr64 != addr64)
  53           {
  54             __set_errno (EOVERFLOW);
  55             return -1;
  56           }
  57         *addr = (uintptr_t) addr64;
  58         break;
  59       }
  60
  61   return res;
  62 }
  63 weak_alias (__arch_prctl, arch_prctl)