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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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#include <asm/fixmap.h>
31
32extern pte_t *kmap_pte;
33extern pgprot_t kmap_prot;
34extern pte_t *pkmap_page_table;
35
36/*
37 * Right now we initialize only a single pte table. It can be extended
38 * easily, subsequent pte tables have to be allocated in one physical
39 * chunk of RAM.
40 */
41/*
42 * We use one full pte table with 4K pages. And with 16K/64K pages pte
43 * table covers enough memory (32MB and 512MB resp.) that both FIXMAP
44 * and PKMAP can be placed in single pte table. We use 1024 pages for
45 * PKMAP in case of 16K/64K pages.
46 */
47#ifdef CONFIG_PPC_4K_PAGES
48#define PKMAP_ORDER PTE_SHIFT
49#else
50#define PKMAP_ORDER 10
51#endif
52#define LAST_PKMAP (1 << PKMAP_ORDER)
53#ifndef CONFIG_PPC_4K_PAGES
54#define PKMAP_BASE (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
55#else
56#define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
57#endif
58#define LAST_PKMAP_MASK (LAST_PKMAP-1)
59#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
60#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
61
62extern void *kmap_high(struct page *page);
63extern void kunmap_high(struct page *page);
64
65static inline void *kmap(struct page *page)
66{
67 might_sleep();
68 if (!PageHighMem(page))
69 return page_address(page);
70 return kmap_high(page);
71}
72
73static inline void kunmap(struct page *page)
74{
75 BUG_ON(in_interrupt());
76 if (!PageHighMem(page))
77 return;
78 kunmap_high(page);
79}
80
81/*
82 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
83 * gives a more generic (and caching) interface. But kmap_atomic can
84 * be used in IRQ contexts, so in some (very limited) cases we need
85 * it.
86 */
87static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
88{
89 unsigned int idx;
90 unsigned long vaddr;
91
92 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
93 pagefault_disable();
94 if (!PageHighMem(page))
95 return page_address(page);
96
97 idx = type + KM_TYPE_NR*smp_processor_id();
98 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
99#ifdef CONFIG_DEBUG_HIGHMEM
100 BUG_ON(!pte_none(*(kmap_pte-idx)));
101#endif
102 __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
103 local_flush_tlb_page(NULL, vaddr);
104
105 return (void*) vaddr;
106}
107
108static inline void *kmap_atomic(struct page *page, enum km_type type)
109{
110 return kmap_atomic_prot(page, type, kmap_prot);
111}
112
113static inline void kunmap_atomic(void *kvaddr, enum km_type type)
114{
115#ifdef CONFIG_DEBUG_HIGHMEM
116 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
117 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
118
119 if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
120 pagefault_enable();
121 return;
122 }
123
124 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
125
126 /*
127 * force other mappings to Oops if they'll try to access
128 * this pte without first remap it
129 */
130 pte_clear(&init_mm, vaddr, kmap_pte-idx);
131 local_flush_tlb_page(NULL, vaddr);
132#endif
133 pagefault_enable();
134}
135
136static inline struct page *kmap_atomic_to_page(void *ptr)
137{
138 unsigned long idx, vaddr = (unsigned long) ptr;
139 pte_t *pte;
140
141 if (vaddr < FIXADDR_START)
142 return virt_to_page(ptr);
143
144 idx = virt_to_fix(vaddr);
145 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
146 return pte_page(*pte);
147}
148
149#define flush_cache_kmaps() flush_cache_all()
150
151#endif /* __KERNEL__ */
152
153#endif /* _ASM_HIGHMEM_H */