arch/powerpc/lib/copyuser_power7_vmx.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  15  *
  16  * Copyright (C) IBM Corporation, 2011
  17  *
  18  * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
  19  *          Anton Blanchard <anton@au.ibm.com>
  20  */
  21 #include <linux/uaccess.h>
  22 #include <linux/hardirq.h>
  23
  24 int enter_vmx_copy(void)
  25 {
  26         if (in_interrupt())
  27                 return 0;
  28
  29         /* This acts as preempt_disable() as well and will make
  30          * enable_kernel_altivec(). We need to disable page faults
  31          * as they can call schedule and thus make us lose the VMX
  32          * context. So on page faults, we just fail which will cause
  33          * a fallback to the normal non-vmx copy.
  34          */
  35         pagefault_disable();
  36
  37         enable_kernel_altivec();
  38
  39         return 1;
  40 }
  41
  42 /*
  43  * This function must return 0 because we tail call optimise when calling
  44  * from __copy_tofrom_user_power7 which returns 0 on success.
  45  */
  46 int exit_vmx_copy(void)
  47 {
  48         pagefault_enable();
  49         return 0;
  50 }