text: /*
   *  linux/arch/arm/mm/copypage-v4wt.S
   *
   *  Copyright (C) 1995-1999 Russell King
   *
   * 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 is for CPUs with a writethrough cache and 'flush ID cache' is
   *  the only supported cache operation.
   */
  #include <linux/init.h>
  #include <linux/highmem.h>
  
  /*
   * ARMv4 optimised copy_user_highpage
   *
   * Since we have writethrough caches, we don't have to worry about
   * dirty data in the cache.  However, we do have to ensure that
   * subsequent reads are up to date.
   */
  static void __naked
  v4wt_copy_user_page(void *kto, const void *kfrom)
  {
  	asm("\
  	stmfd	sp!, {r4, lr}			@ 2\n\
  	mov	r2, %2				@ 1\n\
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4\n\
  1:	stmia	r0!, {r3, r4, ip, lr}		@ 4\n\
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4+1\n\
  	stmia	r0!, {r3, r4, ip, lr}		@ 4\n\
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4\n\
  	stmia	r0!, {r3, r4, ip, lr}		@ 4\n\
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4\n\
  	subs	r2, r2, #1			@ 1\n\
  	stmia	r0!, {r3, r4, ip, lr}		@ 4\n\
  	ldmneia	r1!, {r3, r4, ip, lr}		@ 4\n\
  	bne	1b				@ 1\n\
  	mcr	p15, 0, r2, c7, c7, 0		@ flush ID cache\n\
  	ldmfd	sp!, {r4, pc}			@ 3"
  	:
  	: "r" (kto), "r" (kfrom), "I" (PAGE_SIZE / 64));
  }
  
  void v4wt_copy_user_highpage(struct page *to, struct page *from,
  	unsigned long vaddr)
  {
  	void *kto, *kfrom;
  
  	kto = kmap_atomic(to, KM_USER0);
  	kfrom = kmap_atomic(from, KM_USER1);
  	v4wt_copy_user_page(kto, kfrom);
  	kunmap_atomic(kfrom, KM_USER1);
  	kunmap_atomic(kto, KM_USER0);
  }
  
  /*
   * ARMv4 optimised clear_user_page
   *
   * Same story as above.
   */
  void v4wt_clear_user_highpage(struct page *page, unsigned long vaddr)
  {
  	void *ptr, *kaddr = kmap_atomic(page, KM_USER0);
  	asm volatile("\
  	mov	r1, %2				@ 1\n\
  	mov	r2, #0				@ 1\n\
  	mov	r3, #0				@ 1\n\
  	mov	ip, #0				@ 1\n\
  	mov	lr, #0				@ 1\n\
  1:	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
  	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
  	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
  	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
  	subs	r1, r1, #1			@ 1\n\
  	bne	1b				@ 1\n\
  	mcr	p15, 0, r2, c7, c7, 0		@ flush ID cache"
  	: "=r" (ptr)
  	: "0" (kaddr), "I" (PAGE_SIZE / 64)
  	: "r1", "r2", "r3", "ip", "lr");
  	kunmap_atomic(kaddr, KM_USER0);
  }
  
  struct cpu_user_fns v4wt_user_fns __initdata = {
  	.cpu_clear_user_highpage = v4wt_clear_user_highpage,
  	.cpu_copy_user_highpage	= v4wt_copy_user_highpage,
  };
  