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1 /*
2  *  linux/arch/arm/mm/copypage-v6.c
3  *
4  *  Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 #include <linux/init.h>
11 #include <linux/spinlock.h>
12 #include <linux/mm.h>
13 #include <linux/highmem.h>
14 
15 #include <asm/pgtable.h>
16 #include <asm/shmparam.h>
17 #include <asm/tlbflush.h>
18 #include <asm/cacheflush.h>
19 #include <asm/cachetype.h>
20 
21 #include "mm.h"
22 
23 #if SHMLBA > 16384
24 #error FIX ME
25 #endif
26 
27 #define from_address	(0xffff8000)
28 #define to_address	(0xffffc000)
29 
30 static DEFINE_SPINLOCK(v6_lock);
31 
32 /*
33  * Copy the user page.  No aliasing to deal with so we can just
34  * attack the kernel's existing mapping of these pages.
35  */
v6_copy_user_highpage_nonaliasing(struct page * to,struct page * from,unsigned long vaddr)36 static void v6_copy_user_highpage_nonaliasing(struct page *to,
37 	struct page *from, unsigned long vaddr)
38 {
39 	void *kto, *kfrom;
40 
41 	kfrom = kmap_atomic(from, KM_USER0);
42 	kto = kmap_atomic(to, KM_USER1);
43 	copy_page(kto, kfrom);
44 	kunmap_atomic(kto, KM_USER1);
45 	kunmap_atomic(kfrom, KM_USER0);
46 }
47 
48 /*
49  * Clear the user page.  No aliasing to deal with so we can just
50  * attack the kernel's existing mapping of this page.
51  */
v6_clear_user_highpage_nonaliasing(struct page * page,unsigned long vaddr)52 static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned long vaddr)
53 {
54 	void *kaddr = kmap_atomic(page, KM_USER0);
55 	clear_page(kaddr);
56 	kunmap_atomic(kaddr, KM_USER0);
57 }
58 
59 /*
60  * Discard data in the kernel mapping for the new page.
61  * FIXME: needs this MCRR to be supported.
62  */
discard_old_kernel_data(void * kto)63 static void discard_old_kernel_data(void *kto)
64 {
65 	__asm__("mcrr	p15, 0, %1, %0, c6	@ 0xec401f06"
66 	   :
67 	   : "r" (kto),
68 	     "r" ((unsigned long)kto + PAGE_SIZE - L1_CACHE_BYTES)
69 	   : "cc");
70 }
71 
72 /*
73  * Copy the page, taking account of the cache colour.
74  */
v6_copy_user_highpage_aliasing(struct page * to,struct page * from,unsigned long vaddr)75 static void v6_copy_user_highpage_aliasing(struct page *to,
76 	struct page *from, unsigned long vaddr)
77 {
78 	unsigned int offset = CACHE_COLOUR(vaddr);
79 	unsigned long kfrom, kto;
80 
81 	if (test_and_clear_bit(PG_dcache_dirty, &from->flags))
82 		__flush_dcache_page(page_mapping(from), from);
83 
84 	/* FIXME: not highmem safe */
85 	discard_old_kernel_data(page_address(to));
86 
87 	/*
88 	 * Now copy the page using the same cache colour as the
89 	 * pages ultimate destination.
90 	 */
91 	spin_lock(&v6_lock);
92 
93 	set_pte_ext(TOP_PTE(from_address) + offset, pfn_pte(page_to_pfn(from), PAGE_KERNEL), 0);
94 	set_pte_ext(TOP_PTE(to_address) + offset, pfn_pte(page_to_pfn(to), PAGE_KERNEL), 0);
95 
96 	kfrom = from_address + (offset << PAGE_SHIFT);
97 	kto   = to_address + (offset << PAGE_SHIFT);
98 
99 	flush_tlb_kernel_page(kfrom);
100 	flush_tlb_kernel_page(kto);
101 
102 	copy_page((void *)kto, (void *)kfrom);
103 
104 	spin_unlock(&v6_lock);
105 }
106 
107 /*
108  * Clear the user page.  We need to deal with the aliasing issues,
109  * so remap the kernel page into the same cache colour as the user
110  * page.
111  */
v6_clear_user_highpage_aliasing(struct page * page,unsigned long vaddr)112 static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
113 {
114 	unsigned int offset = CACHE_COLOUR(vaddr);
115 	unsigned long to = to_address + (offset << PAGE_SHIFT);
116 
117 	/* FIXME: not highmem safe */
118 	discard_old_kernel_data(page_address(page));
119 
120 	/*
121 	 * Now clear the page using the same cache colour as
122 	 * the pages ultimate destination.
123 	 */
124 	spin_lock(&v6_lock);
125 
126 	set_pte_ext(TOP_PTE(to_address) + offset, pfn_pte(page_to_pfn(page), PAGE_KERNEL), 0);
127 	flush_tlb_kernel_page(to);
128 	clear_page((void *)to);
129 
130 	spin_unlock(&v6_lock);
131 }
132 
133 struct cpu_user_fns v6_user_fns __initdata = {
134 	.cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
135 	.cpu_copy_user_highpage	= v6_copy_user_highpage_nonaliasing,
136 };
137 
v6_userpage_init(void)138 static int __init v6_userpage_init(void)
139 {
140 	if (cache_is_vipt_aliasing()) {
141 		cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
142 		cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
143 	}
144 
145 	return 0;
146 }
147 
148 core_initcall(v6_userpage_init);
149