GNU Linux-libre 4.19.264-gnu1
[releases.git] / arch / arm / mm / highmem.c
1 /*
2  * arch/arm/mm/highmem.c -- ARM highmem support
3  *
4  * Author:      Nicolas Pitre
5  * Created:     september 8, 2008
6  * Copyright:   Marvell Semiconductors Inc.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12
13 #include <linux/module.h>
14 #include <linux/highmem.h>
15 #include <linux/interrupt.h>
16 #include <asm/fixmap.h>
17 #include <asm/cacheflush.h>
18 #include <asm/tlbflush.h>
19 #include "mm.h"
20
21 static inline void set_fixmap_pte(int idx, pte_t pte)
22 {
23         unsigned long vaddr = __fix_to_virt(idx);
24         pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
25
26         set_pte_ext(ptep, pte, 0);
27         local_flush_tlb_kernel_page(vaddr);
28 }
29
30 static inline pte_t get_fixmap_pte(unsigned long vaddr)
31 {
32         pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
33
34         return *ptep;
35 }
36
37 void *kmap(struct page *page)
38 {
39         might_sleep();
40         if (!PageHighMem(page))
41                 return page_address(page);
42         return kmap_high(page);
43 }
44 EXPORT_SYMBOL(kmap);
45
46 void kunmap(struct page *page)
47 {
48         BUG_ON(in_interrupt());
49         if (!PageHighMem(page))
50                 return;
51         kunmap_high(page);
52 }
53 EXPORT_SYMBOL(kunmap);
54
55 void *kmap_atomic(struct page *page)
56 {
57         unsigned int idx;
58         unsigned long vaddr;
59         void *kmap;
60         int type;
61
62         preempt_disable();
63         pagefault_disable();
64         if (!PageHighMem(page))
65                 return page_address(page);
66
67 #ifdef CONFIG_DEBUG_HIGHMEM
68         /*
69          * There is no cache coherency issue when non VIVT, so force the
70          * dedicated kmap usage for better debugging purposes in that case.
71          */
72         if (!cache_is_vivt())
73                 kmap = NULL;
74         else
75 #endif
76                 kmap = kmap_high_get(page);
77         if (kmap)
78                 return kmap;
79
80         type = kmap_atomic_idx_push();
81
82         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
83         vaddr = __fix_to_virt(idx);
84 #ifdef CONFIG_DEBUG_HIGHMEM
85         /*
86          * With debugging enabled, kunmap_atomic forces that entry to 0.
87          * Make sure it was indeed properly unmapped.
88          */
89         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
90 #endif
91         /*
92          * When debugging is off, kunmap_atomic leaves the previous mapping
93          * in place, so the contained TLB flush ensures the TLB is updated
94          * with the new mapping.
95          */
96         set_fixmap_pte(idx, mk_pte(page, kmap_prot));
97
98         return (void *)vaddr;
99 }
100 EXPORT_SYMBOL(kmap_atomic);
101
102 void __kunmap_atomic(void *kvaddr)
103 {
104         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
105         int idx, type;
106
107         if (kvaddr >= (void *)FIXADDR_START) {
108                 type = kmap_atomic_idx();
109                 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
110
111                 if (cache_is_vivt())
112                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
113 #ifdef CONFIG_DEBUG_HIGHMEM
114                 BUG_ON(vaddr != __fix_to_virt(idx));
115                 set_fixmap_pte(idx, __pte(0));
116 #else
117                 (void) idx;  /* to kill a warning */
118 #endif
119                 kmap_atomic_idx_pop();
120         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
121                 /* this address was obtained through kmap_high_get() */
122                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
123         }
124         pagefault_enable();
125         preempt_enable();
126 }
127 EXPORT_SYMBOL(__kunmap_atomic);
128
129 void *kmap_atomic_pfn(unsigned long pfn)
130 {
131         unsigned long vaddr;
132         int idx, type;
133         struct page *page = pfn_to_page(pfn);
134
135         preempt_disable();
136         pagefault_disable();
137         if (!PageHighMem(page))
138                 return page_address(page);
139
140         type = kmap_atomic_idx_push();
141         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
142         vaddr = __fix_to_virt(idx);
143 #ifdef CONFIG_DEBUG_HIGHMEM
144         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
145 #endif
146         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
147
148         return (void *)vaddr;
149 }