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kernel/linux-imx6_3.14.28/arch/powerpc/lib/vmx-helper.c 1.9 KB
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  /*
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   * Copyright (C) IBM Corporation, 2011
   *
   * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
   *          Anton Blanchard <anton@au.ibm.com>
   */
  #include <linux/uaccess.h>
  #include <linux/hardirq.h>
  #include <asm/switch_to.h>
  
  int enter_vmx_usercopy(void)
  {
  	if (in_interrupt())
  		return 0;
  
  	/* This acts as preempt_disable() as well and will make
  	 * enable_kernel_altivec(). We need to disable page faults
  	 * as they can call schedule and thus make us lose the VMX
  	 * context. So on page faults, we just fail which will cause
  	 * a fallback to the normal non-vmx copy.
  	 */
  	pagefault_disable();
  
  	enable_kernel_altivec();
  
  	return 1;
  }
  
  /*
   * This function must return 0 because we tail call optimise when calling
   * from __copy_tofrom_user_power7 which returns 0 on success.
   */
  int exit_vmx_usercopy(void)
  {
  	pagefault_enable();
  	return 0;
  }
  
  int enter_vmx_copy(void)
  {
  	if (in_interrupt())
  		return 0;
  
  	preempt_disable();
  
  	enable_kernel_altivec();
  
  	return 1;
  }
  
  /*
   * All calls to this function will be optimised into tail calls. We are
   * passed a pointer to the destination which we return as required by a
   * memcpy implementation.
   */
  void *exit_vmx_copy(void *dest)
  {
  	preempt_enable();
  	return dest;
  }