Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * highmem.h: virtual kernel memory mappings for high memory
3 *
4 * Used in CONFIG_HIGHMEM systems for memory pages which
5 * are not addressable by direct kernel virtual addresses.
6 *
7 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
8 * Gerhard.Wichert@pdb.siemens.de
9 *
10 *
11 * Redesigned the x86 32-bit VM architecture to deal with
12 * up to 16 Terabyte physical memory. With current x86 CPUs
13 * we now support up to 64 Gigabytes physical RAM.
14 *
15 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
16 */
17#ifndef _ASM_HIGHMEM_H
18#define _ASM_HIGHMEM_H
19
20#ifdef __KERNEL__
21
22#include <linux/init.h>
23#include <linux/interrupt.h>
24#include <asm/kmap_types.h>
25
26/* undef for production */
27#define HIGHMEM_DEBUG 1
28
29/* declarations for highmem.c */
30extern unsigned long highstart_pfn, highend_pfn;
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#define PKMAP_BASE (0xfe000000UL)
42#define LAST_PKMAP 1024
43#define LAST_PKMAP_MASK (LAST_PKMAP-1)
44#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
45#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
46
47extern void * kmap_high(struct page *page);
48extern void kunmap_high(struct page *page);
49
50/*
51 * CONFIG_LIMITED_DMA is for systems with DMA limitations such as Momentum's
52 * Jaguar ATX. This option exploits the highmem code in the kernel so is
53 * always enabled together with CONFIG_HIGHMEM but at this time doesn't
54 * actually add highmem functionality.
55 */
56
57#ifdef CONFIG_LIMITED_DMA
58
59/*
60 * These are the default functions for the no-highmem case from
61 * <linux/highmem.h>
62 */
63static inline void *kmap(struct page *page)
64{
65 might_sleep();
66 return page_address(page);
67}
68
69#define kunmap(page) do { (void) (page); } while (0)
70
71static inline void *kmap_atomic(struct page *page, enum km_type type)
72{
73 return page_address(page);
74}
75
76static inline void kunmap_atomic(void *kvaddr, enum km_type type) { }
77#define kmap_atomic_pfn(pfn, idx) page_address(pfn_to_page(pfn))
78
79#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
80
81#define flush_cache_kmaps() do { } while (0)
82
83#else /* LIMITED_DMA */
84
85extern void *__kmap(struct page *page);
86extern void __kunmap(struct page *page);
87extern void *__kmap_atomic(struct page *page, enum km_type type);
88extern void __kunmap_atomic(void *kvaddr, enum km_type type);
89extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
90extern struct page *__kmap_atomic_to_page(void *ptr);
91
92#define kmap __kmap
93#define kunmap __kunmap
94#define kmap_atomic __kmap_atomic
95#define kunmap_atomic __kunmap_atomic
96#define kmap_atomic_to_page __kmap_atomic_to_page
97
98#define flush_cache_kmaps() flush_cache_all()
99
100#endif /* LIMITED_DMA */
101
102#endif /* __KERNEL__ */
103
104#endif /* _ASM_HIGHMEM_H */