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Linux/arch/arm/mm/highmem.c

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  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 }
150 

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