xref: /linux/arch/arm/mm/copypage-v6.c (revision 2da68a77) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/mm/copypage-v6.c
4  *
5  *  Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
6  */
7 #include <linux/init.h>
8 #include <linux/spinlock.h>
9 #include <linux/mm.h>
10 #include <linux/highmem.h>
11 #include <linux/pagemap.h>
12 
13 #include <asm/shmparam.h>
14 #include <asm/tlbflush.h>
15 #include <asm/cacheflush.h>
16 #include <asm/cachetype.h>
17 
18 #include "mm.h"
19 
20 #if SHMLBA > 16384
21 #error FIX ME
22 #endif
23 
24 static DEFINE_RAW_SPINLOCK(v6_lock);
25 
26 /*
27  * Copy the user page.  No aliasing to deal with so we can just
28  * attack the kernel's existing mapping of these pages.
29  */
30 static void v6_copy_user_highpage_nonaliasing(struct page *to,
31 	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
32 {
33 	void *kto, *kfrom;
34 
35 	kfrom = kmap_atomic(from);
36 	kto = kmap_atomic(to);
37 	copy_page(kto, kfrom);
38 	kunmap_atomic(kto);
39 	kunmap_atomic(kfrom);
40 }
41 
42 /*
43  * Clear the user page.  No aliasing to deal with so we can just
44  * attack the kernel's existing mapping of this page.
45  */
46 static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned long vaddr)
47 {
48 	void *kaddr = kmap_atomic(page);
49 	clear_page(kaddr);
50 	kunmap_atomic(kaddr);
51 }
52 
53 /*
54  * Discard data in the kernel mapping for the new page.
55  * FIXME: needs this MCRR to be supported.
56  */
57 static void discard_old_kernel_data(void *kto)
58 {
59 	__asm__("mcrr	p15, 0, %1, %0, c6	@ 0xec401f06"
60 	   :
61 	   : "r" (kto),
62 	     "r" ((unsigned long)kto + PAGE_SIZE - 1)
63 	   : "cc");
64 }
65 
66 /*
67  * Copy the page, taking account of the cache colour.
68  */
69 static void v6_copy_user_highpage_aliasing(struct page *to,
70 	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
71 {
72 	unsigned int offset = CACHE_COLOUR(vaddr);
73 	unsigned long kfrom, kto;
74 
75 	if (!test_and_set_bit(PG_dcache_clean, &from->flags))
76 		__flush_dcache_page(page_mapping_file(from), from);
77 
78 	/* FIXME: not highmem safe */
79 	discard_old_kernel_data(page_address(to));
80 
81 	/*
82 	 * Now copy the page using the same cache colour as the
83 	 * pages ultimate destination.
84 	 */
85 	raw_spin_lock(&v6_lock);
86 
87 	kfrom = COPYPAGE_V6_FROM + (offset << PAGE_SHIFT);
88 	kto   = COPYPAGE_V6_TO + (offset << PAGE_SHIFT);
89 
90 	set_top_pte(kfrom, mk_pte(from, PAGE_KERNEL));
91 	set_top_pte(kto, mk_pte(to, PAGE_KERNEL));
92 
93 	copy_page((void *)kto, (void *)kfrom);
94 
95 	raw_spin_unlock(&v6_lock);
96 }
97 
98 /*
99  * Clear the user page.  We need to deal with the aliasing issues,
100  * so remap the kernel page into the same cache colour as the user
101  * page.
102  */
103 static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
104 {
105 	unsigned long to = COPYPAGE_V6_TO + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
106 
107 	/* FIXME: not highmem safe */
108 	discard_old_kernel_data(page_address(page));
109 
110 	/*
111 	 * Now clear the page using the same cache colour as
112 	 * the pages ultimate destination.
113 	 */
114 	raw_spin_lock(&v6_lock);
115 
116 	set_top_pte(to, mk_pte(page, PAGE_KERNEL));
117 	clear_page((void *)to);
118 
119 	raw_spin_unlock(&v6_lock);
120 }
121 
122 struct cpu_user_fns v6_user_fns __initdata = {
123 	.cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
124 	.cpu_copy_user_highpage	= v6_copy_user_highpage_nonaliasing,
125 };
126 
127 static int __init v6_userpage_init(void)
128 {
129 	if (cache_is_vipt_aliasing()) {
130 		cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
131 		cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
132 	}
133 
134 	return 0;
135 }
136 
137 core_initcall(v6_userpage_init);
138