/*
   * Based on arch/arm/lib/clear_user.S
   *
   * Copyright (C) 2012 ARM Ltd.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * 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, see <http://www.gnu.org/licenses/>.
   */
  #include <linux/linkage.h>
  
  #include <asm/asm-uaccess.h>
  
  	.text
  
  /* Prototype: int __arch_clear_user(void *addr, size_t sz)
   * Purpose  : clear some user memory
   * Params   : addr - user memory address to clear
   *          : sz   - number of bytes to clear
   * Returns  : number of bytes NOT cleared
   *
   * Alignment fixed up by hardware.
   */
  ENTRY(__arch_clear_user)
  	uaccess_enable_not_uao x2, x3, x4
  	mov	x2, x1			// save the size for fixup return
  	subs	x1, x1, #8
  	b.mi	2f
  1:
  uao_user_alternative 9f, str, sttr, xzr, x0, 8
  	subs	x1, x1, #8
  	b.pl	1b
  2:	adds	x1, x1, #4
  	b.mi	3f
  uao_user_alternative 9f, str, sttr, wzr, x0, 4
  	sub	x1, x1, #4
  3:	adds	x1, x1, #2
  	b.mi	4f
  uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
  	sub	x1, x1, #2
  4:	adds	x1, x1, #1
  	b.mi	5f
  uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
  5:	mov	x0, #0
  	uaccess_disable_not_uao x2, x3
  	ret
  ENDPROC(__arch_clear_user)
  
  	.section .fixup,"ax"
  	.align	2
  9:	mov	x0, x2			// return the original size
  	ret
  	.previous