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
24static 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 */
30static 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 */
46static 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 */
57static 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 */
69static void v6_copy_user_highpage_aliasing(struct page *to,
70	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
71{
72	struct folio *src = page_folio(from);
73	unsigned int offset = CACHE_COLOUR(vaddr);
74	unsigned long kfrom, kto;
75
76	if (!test_and_set_bit(PG_dcache_clean, &src->flags))
77		__flush_dcache_folio(folio_flush_mapping(src), src);
78
79	/* FIXME: not highmem safe */
80	discard_old_kernel_data(page_address(to));
81
82	/*
83	 * Now copy the page using the same cache colour as the
84	 * pages ultimate destination.
85	 */
86	raw_spin_lock(&v6_lock);
87
88	kfrom = COPYPAGE_V6_FROM + (offset << PAGE_SHIFT);
89	kto   = COPYPAGE_V6_TO + (offset << PAGE_SHIFT);
90
91	set_top_pte(kfrom, mk_pte(from, PAGE_KERNEL));
92	set_top_pte(kto, mk_pte(to, PAGE_KERNEL));
93
94	copy_page((void *)kto, (void *)kfrom);
95
96	raw_spin_unlock(&v6_lock);
97}
98
99/*
100 * Clear the user page.  We need to deal with the aliasing issues,
101 * so remap the kernel page into the same cache colour as the user
102 * page.
103 */
104static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
105{
106	unsigned long to = COPYPAGE_V6_TO + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
107
108	/* FIXME: not highmem safe */
109	discard_old_kernel_data(page_address(page));
110
111	/*
112	 * Now clear the page using the same cache colour as
113	 * the pages ultimate destination.
114	 */
115	raw_spin_lock(&v6_lock);
116
117	set_top_pte(to, mk_pte(page, PAGE_KERNEL));
118	clear_page((void *)to);
119
120	raw_spin_unlock(&v6_lock);
121}
122
123struct cpu_user_fns v6_user_fns __initdata = {
124	.cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
125	.cpu_copy_user_highpage	= v6_copy_user_highpage_nonaliasing,
126};
127
128static int __init v6_userpage_init(void)
129{
130	if (cache_is_vipt_aliasing()) {
131		cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
132		cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
133	}
134
135	return 0;
136}
137
138core_initcall(v6_userpage_init);
139