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review.evervolv.com / android_kernel_oneplus_msm8996 / 854af9578cb84e4ca3cb1551a6be40c4e81bb455 / . / include / asm-ppc / highmem.h
blob: 1d2c4ef81c2233673fa64e8569e78b08ed923121 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/*
2 * highmem.h: virtual kernel memory mappings for high memory
3 *
4 * PowerPC version, stolen from the i386 version.
5 *
6 * Used in CONFIG_HIGHMEM systems for memory pages which
7 * are not addressable by direct kernel virtual addresses.
8 *
9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
10 * Gerhard.Wichert@pdb.siemens.de
11 *
12 *
13 * Redesigned the x86 32-bit VM architecture to deal with
14 * up to 16 Terrabyte physical memory. With current x86 CPUs
15 * we now support up to 64 Gigabytes physical RAM.
16 *
17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
18 */
19
20#ifndef _ASM_HIGHMEM_H
21#define _ASM_HIGHMEM_H
22
23#ifdef __KERNEL__
24
25#include <linux/init.h>
26#include <linux/interrupt.h>
27#include <asm/kmap_types.h>
28#include <asm/tlbflush.h>
29#include <asm/page.h>
30
31/* undef for production */
32#define HIGHMEM_DEBUG 1
33
34extern pte_t *kmap_pte;
35extern pgprot_t kmap_prot;
36extern pte_t *pkmap_page_table;
37
38/*
39 * Right now we initialize only a single pte table. It can be extended
40 * easily, subsequent pte tables have to be allocated in one physical
41 * chunk of RAM.
42 */
43#define PKMAP_BASE CONFIG_HIGHMEM_START
44#define LAST_PKMAP (1 << PTE_SHIFT)
45#define LAST_PKMAP_MASK (LAST_PKMAP-1)
46#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
47#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
48
49#define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL)
50
51extern void *kmap_high(struct page *page);
52extern void kunmap_high(struct page *page);
53
54static inline void *kmap(struct page *page)
55{
56 might_sleep();
57 if (!PageHighMem(page))
58 return page_address(page);
59 return kmap_high(page);
60}
61
62static inline void kunmap(struct page *page)
63{
64 BUG_ON(in_interrupt());
65 if (!PageHighMem(page))
66 return;
67 kunmap_high(page);
68}
69
70/*
71 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
72 * gives a more generic (and caching) interface. But kmap_atomic can
73 * be used in IRQ contexts, so in some (very limited) cases we need
74 * it.
75 */
76static inline void *kmap_atomic(struct page *page, enum km_type type)
77{
78 unsigned int idx;
79 unsigned long vaddr;
80
81 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
82 inc_preempt_count();
83 if (!PageHighMem(page))
84 return page_address(page);
85
86 idx = type + KM_TYPE_NR*smp_processor_id();
87 vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE;
88#ifdef HIGHMEM_DEBUG
89 BUG_ON(!pte_none(*(kmap_pte+idx)));
90#endif
91 set_pte_at(&init_mm, vaddr, kmap_pte+idx, mk_pte(page, kmap_prot));
92 flush_tlb_page(NULL, vaddr);
93
94 return (void*) vaddr;
95}
96
97static inline void kunmap_atomic(void *kvaddr, enum km_type type)
98{
99#ifdef HIGHMEM_DEBUG
100 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
101 unsigned int idx = type + KM_TYPE_NR*smp_processor_id();
102
103 if (vaddr < KMAP_FIX_BEGIN) { // FIXME
104 dec_preempt_count();
105 preempt_check_resched();
106 return;
107 }
108
109 BUG_ON(vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE);
110
111 /*
112 * force other mappings to Oops if they'll try to access
113 * this pte without first remap it
114 */
115 pte_clear(&init_mm, vaddr, kmap_pte+idx);
116 flush_tlb_page(NULL, vaddr);
117#endif
118 dec_preempt_count();
119 preempt_check_resched();
120}
121
122static inline struct page *kmap_atomic_to_page(void *ptr)
123{
124 unsigned long idx, vaddr = (unsigned long) ptr;
125
126 if (vaddr < KMAP_FIX_BEGIN)
127 return virt_to_page(ptr);
128
129 idx = (vaddr - KMAP_FIX_BEGIN) >> PAGE_SHIFT;
130 return pte_page(kmap_pte[idx]);
131}
132
133#define flush_cache_kmaps() flush_cache_all()
134
135#endif /* __KERNEL__ */
136
137#endif /* _ASM_HIGHMEM_H */