blob: 5d99b6489d569d44e54a3781734e797d72100b5c [file] [log] [blame]
Kumar Gala33d71d22007-08-20 08:50:28 -05001/*
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>
Kumar Gala2c419bd2008-04-23 23:05:20 +100030#include <asm/fixmap.h>
Kumar Gala33d71d22007-08-20 08:50:28 -050031
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 */
Kumar Gala33d71d22007-08-20 08:50:28 -050041#define LAST_PKMAP (1 << PTE_SHIFT)
42#define LAST_PKMAP_MASK (LAST_PKMAP-1)
Kumar Gala2c419bd2008-04-23 23:05:20 +100043#define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
Kumar Gala33d71d22007-08-20 08:50:28 -050044#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
45#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
46
Kumar Gala33d71d22007-08-20 08:50:28 -050047extern void *kmap_high(struct page *page);
48extern void kunmap_high(struct page *page);
49
50static inline void *kmap(struct page *page)
51{
52 might_sleep();
53 if (!PageHighMem(page))
54 return page_address(page);
55 return kmap_high(page);
56}
57
58static inline void kunmap(struct page *page)
59{
60 BUG_ON(in_interrupt());
61 if (!PageHighMem(page))
62 return;
63 kunmap_high(page);
64}
65
66/*
67 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
68 * gives a more generic (and caching) interface. But kmap_atomic can
69 * be used in IRQ contexts, so in some (very limited) cases we need
70 * it.
71 */
Kumar Gala2c419bd2008-04-23 23:05:20 +100072static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
Kumar Gala33d71d22007-08-20 08:50:28 -050073{
74 unsigned int idx;
75 unsigned long vaddr;
76
77 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
78 pagefault_disable();
79 if (!PageHighMem(page))
80 return page_address(page);
81
82 idx = type + KM_TYPE_NR*smp_processor_id();
Kumar Gala2c419bd2008-04-23 23:05:20 +100083 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
84#ifdef CONFIG_DEBUG_HIGHMEM
85 BUG_ON(!pte_none(*(kmap_pte-idx)));
Kumar Gala33d71d22007-08-20 08:50:28 -050086#endif
Kumar Gala2c419bd2008-04-23 23:05:20 +100087 set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
Kumar Gala33d71d22007-08-20 08:50:28 -050088 flush_tlb_page(NULL, vaddr);
89
90 return (void*) vaddr;
91}
92
Kumar Gala2c419bd2008-04-23 23:05:20 +100093static inline void *kmap_atomic(struct page *page, enum km_type type)
94{
95 return kmap_atomic_prot(page, type, kmap_prot);
96}
97
Kumar Gala33d71d22007-08-20 08:50:28 -050098static inline void kunmap_atomic(void *kvaddr, enum km_type type)
99{
Kumar Gala2c419bd2008-04-23 23:05:20 +1000100#ifdef CONFIG_DEBUG_HIGHMEM
Kumar Gala33d71d22007-08-20 08:50:28 -0500101 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
Kumar Gala2c419bd2008-04-23 23:05:20 +1000102 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
Kumar Gala33d71d22007-08-20 08:50:28 -0500103
Kumar Gala2c419bd2008-04-23 23:05:20 +1000104 if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
Kumar Gala33d71d22007-08-20 08:50:28 -0500105 pagefault_enable();
106 return;
107 }
108
Kumar Gala2c419bd2008-04-23 23:05:20 +1000109 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
Kumar Gala33d71d22007-08-20 08:50:28 -0500110
111 /*
112 * force other mappings to Oops if they'll try to access
113 * this pte without first remap it
114 */
Kumar Gala2c419bd2008-04-23 23:05:20 +1000115 pte_clear(&init_mm, vaddr, kmap_pte-idx);
Kumar Gala33d71d22007-08-20 08:50:28 -0500116 flush_tlb_page(NULL, vaddr);
117#endif
118 pagefault_enable();
119}
120
121static inline struct page *kmap_atomic_to_page(void *ptr)
122{
123 unsigned long idx, vaddr = (unsigned long) ptr;
Kumar Gala2c419bd2008-04-23 23:05:20 +1000124 pte_t *pte;
Kumar Gala33d71d22007-08-20 08:50:28 -0500125
Kumar Gala2c419bd2008-04-23 23:05:20 +1000126 if (vaddr < FIXADDR_START)
Kumar Gala33d71d22007-08-20 08:50:28 -0500127 return virt_to_page(ptr);
128
Kumar Gala2c419bd2008-04-23 23:05:20 +1000129 idx = virt_to_fix(vaddr);
130 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
131 return pte_page(*pte);
Kumar Gala33d71d22007-08-20 08:50:28 -0500132}
133
134#define flush_cache_kmaps() flush_cache_all()
135
136#endif /* __KERNEL__ */
137
138#endif /* _ASM_HIGHMEM_H */