WSL2-Linux-Kernel/arch/arm/mm/copypage-v6.c

/*
 *  linux/arch/arm/mm/copypage-v6.c
 *
 *  Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
 *
 * 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/spinlock.h>
#include <linux/mm.h>

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/shmparam.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>

#if SHMLBA > 16384
#error FIX ME
#endif

#define from_address	(0xffff8000)
#define to_address	(0xffffc000)

#define TOP_PTE(x)	pte_offset_kernel(top_pmd, x)

static DEFINE_SPINLOCK(v6_lock);

/*
 * Copy the user page.  No aliasing to deal with so we can just
 * attack the kernel's existing mapping of these pages.
 */
static void v6_copy_user_page_nonaliasing(void *kto, const void *kfrom, unsigned long vaddr)
{
	copy_page(kto, kfrom);
}

/*
 * Clear the user page.  No aliasing to deal with so we can just
 * attack the kernel's existing mapping of this page.
 */
static void v6_clear_user_page_nonaliasing(void *kaddr, unsigned long vaddr)
{
	clear_page(kaddr);
}

/*
 * Copy the page, taking account of the cache colour.
 */
static void v6_copy_user_page_aliasing(void *kto, const void *kfrom, unsigned long vaddr)
{
	unsigned int offset = CACHE_COLOUR(vaddr);
	unsigned long from, to;

	/*
	 * Discard data in the kernel mapping for the new page.
	 * FIXME: needs this MCRR to be supported.
	 */
	__asm__("mcrr	p15, 0, %1, %0, c6	@ 0xec401f06"
	   :
	   : "r" (kto),
	     "r" ((unsigned long)kto + PAGE_SIZE - L1_CACHE_BYTES)
	   : "cc");

	/*
	 * Now copy the page using the same cache colour as the
	 * pages ultimate destination.
	 */
	spin_lock(&v6_lock);

	set_pte(TOP_PTE(from_address) + offset, pfn_pte(__pa(kfrom) >> PAGE_SHIFT, PAGE_KERNEL));
	set_pte(TOP_PTE(to_address) + offset, pfn_pte(__pa(kto) >> PAGE_SHIFT, PAGE_KERNEL));

	from = from_address + (offset << PAGE_SHIFT);
	to   = to_address + (offset << PAGE_SHIFT);

	flush_tlb_kernel_page(from);
	flush_tlb_kernel_page(to);

	copy_page((void *)to, (void *)from);

	spin_unlock(&v6_lock);
}

/*
 * Clear the user page.  We need to deal with the aliasing issues,
 * so remap the kernel page into the same cache colour as the user
 * page.
 */
static void v6_clear_user_page_aliasing(void *kaddr, unsigned long vaddr)
{
	unsigned int offset = CACHE_COLOUR(vaddr);
	unsigned long to = to_address + (offset << PAGE_SHIFT);

	/*
	 * Discard data in the kernel mapping for the new page
	 * FIXME: needs this MCRR to be supported.
	 */
	__asm__("mcrr	p15, 0, %1, %0, c6	@ 0xec401f06"
	   :
	   : "r" (kaddr),
	     "r" ((unsigned long)kaddr + PAGE_SIZE - L1_CACHE_BYTES)
	   : "cc");

	/*
	 * Now clear the page using the same cache colour as
	 * the pages ultimate destination.
	 */
	spin_lock(&v6_lock);

	set_pte(TOP_PTE(to_address) + offset, pfn_pte(__pa(kaddr) >> PAGE_SHIFT, PAGE_KERNEL));
	flush_tlb_kernel_page(to);
	clear_page((void *)to);

	spin_unlock(&v6_lock);
}

struct cpu_user_fns v6_user_fns __initdata = {
	.cpu_clear_user_page	= v6_clear_user_page_nonaliasing,
	.cpu_copy_user_page	= v6_copy_user_page_nonaliasing,
};

static int __init v6_userpage_init(void)
{
	if (cache_is_vipt_aliasing()) {
		cpu_user.cpu_clear_user_page = v6_clear_user_page_aliasing;
		cpu_user.cpu_copy_user_page = v6_copy_user_page_aliasing;
	}

	return 0;
}

core_initcall(v6_userpage_init);