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kernel/linux-imx6_3.14.28/arch/arm/mm/copypage-v4wb.c 2.79 KB
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  /*
   *  linux/arch/arm/mm/copypage-v4wb.c
   *
   *  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.
   */
  #include <linux/init.h>
  #include <linux/highmem.h>
  
  /*
   * ARMv4 optimised copy_user_highpage
   *
   * We flush the destination cache lines just before we write the data into the
   * corresponding address.  Since the Dcache is read-allocate, this removes the
   * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
   * and merged as appropriate.
   *
   * Note: We rely on all ARMv4 processors implementing the "invalidate D line"
   * instruction.  If your processor does not supply this, you have to write your
   * own copy_user_highpage that does the right thing.
   */
  static void __naked
  v4wb_copy_user_page(void *kto, const void *kfrom)
  {
  	asm("\
  	stmfd	sp!, {r4, lr}			@ 2
  \
  	mov	r2, %2				@ 1
  \
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4
  \
  1:	mcr	p15, 0, r0, c7, c6, 1		@ 1   invalidate D line
  \
  	stmia	r0!, {r3, r4, ip, lr}		@ 4
  \
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4+1
  \
  	stmia	r0!, {r3, r4, ip, lr}		@ 4
  \
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4
  \
  	mcr	p15, 0, r0, c7, c6, 1		@ 1   invalidate D line
  \
  	stmia	r0!, {r3, r4, ip, lr}		@ 4
  \
  	ldmia	r1!, {r3, r4, ip, lr}		@ 4
  \
  	subs	r2, r2, #1			@ 1
  \
  	stmia	r0!, {r3, r4, ip, lr}		@ 4
  \
  	ldmneia	r1!, {r3, r4, ip, lr}		@ 4
  \
  	bne	1b				@ 1
  \
  	mcr	p15, 0, r1, c7, c10, 4		@ 1   drain WB
  \
  	ldmfd	 sp!, {r4, pc}			@ 3"
  	:
  	: "r" (kto), "r" (kfrom), "I" (PAGE_SIZE / 64));
  }
  
  void v4wb_copy_user_highpage(struct page *to, struct page *from,
  	unsigned long vaddr, struct vm_area_struct *vma)
  {
  	void *kto, *kfrom;
  
  	kto = kmap_atomic(to);
  	kfrom = kmap_atomic(from);
  	flush_cache_page(vma, vaddr, page_to_pfn(from));
  	v4wb_copy_user_page(kto, kfrom);
  	kunmap_atomic(kfrom);
  	kunmap_atomic(kto);
  }
  
  /*
   * ARMv4 optimised clear_user_page
   *
   * Same story as above.
   */
  void v4wb_clear_user_highpage(struct page *page, unsigned long vaddr)
  {
  	void *ptr, *kaddr = kmap_atomic(page);
  	asm volatile("\
  	mov	r1, %2				@ 1
  \
  	mov	r2, #0				@ 1
  \
  	mov	r3, #0				@ 1
  \
  	mov	ip, #0				@ 1
  \
  	mov	lr, #0				@ 1
  \
  1:	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line
  \
  	stmia	%0!, {r2, r3, ip, lr}		@ 4
  \
  	stmia	%0!, {r2, r3, ip, lr}		@ 4
  \
  	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line
  \
  	stmia	%0!, {r2, r3, ip, lr}		@ 4
  \
  	stmia	%0!, {r2, r3, ip, lr}		@ 4
  \
  	subs	r1, r1, #1			@ 1
  \
  	bne	1b				@ 1
  \
  	mcr	p15, 0, r1, c7, c10, 4		@ 1   drain WB"
  	: "=r" (ptr)
  	: "0" (kaddr), "I" (PAGE_SIZE / 64)
  	: "r1", "r2", "r3", "ip", "lr");
  	kunmap_atomic(kaddr);
  }
  
  struct cpu_user_fns v4wb_user_fns __initdata = {
  	.cpu_clear_user_highpage = v4wb_clear_user_highpage,
  	.cpu_copy_user_highpage	= v4wb_copy_user_highpage,
  };