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	pagefault_disable();
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) {
104		pagefault_enable();
105		return;
106	}
107
108	BUG_ON(vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE);
109
110	/*
111	 * force other mappings to Oops if they'll try to access
112	 * this pte without first remap it
113	 */
114	pte_clear(&init_mm, vaddr, kmap_pte+idx);
115	flush_tlb_page(NULL, vaddr);
116#endif
117	pagefault_enable();
118}
119
120static inline struct page *kmap_atomic_to_page(void *ptr)
121{
122	unsigned long idx, vaddr = (unsigned long) ptr;
123
124	if (vaddr < KMAP_FIX_BEGIN)
125		return virt_to_page(ptr);
126
127	idx = (vaddr - KMAP_FIX_BEGIN) >> PAGE_SHIFT;
128	return pte_page(kmap_pte[idx]);
129}
130
131#define flush_cache_kmaps()	flush_cache_all()
132
133#endif /* __KERNEL__ */
134
135#endif /* _ASM_HIGHMEM_H */
136