2 * highmem.h: virtual kernel memory mappings for high memory
4 * Used in CONFIG_HIGHMEM systems for memory pages which
5 * are not addressable by direct kernel virtual addresses.
7 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
8 * Gerhard.Wichert@pdb.siemens.de
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.
15 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
18 #ifndef _ASM_HIGHMEM_H
19 #define _ASM_HIGHMEM_H
23 #include <linux/config.h>
24 #include <linux/init.h>
25 #include <linux/interrupt.h>
26 #include <asm/kmap_types.h>
27 #include <asm/pgtable.h>
29 #ifdef CONFIG_DEBUG_HIGHMEM
30 #define HIGHMEM_DEBUG 1
32 #define HIGHMEM_DEBUG 0
35 /* declarations for highmem.c */
36 extern unsigned long highstart_pfn, highend_pfn;
38 extern pte_t *kmap_pte;
39 extern pgprot_t kmap_prot;
40 extern pte_t *pkmap_page_table;
42 extern void kmap_init(void) __init;
45 * Right now we initialize only a single pte table. It can be extended
46 * easily, subsequent pte tables have to be allocated in one physical
49 #define PKMAP_BASE (0xfe000000UL)
51 #define LAST_PKMAP 512
53 #define LAST_PKMAP 1024
55 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
56 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
57 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
59 extern void * FASTCALL(kmap_high(struct page *page));
60 extern void FASTCALL(kunmap_high(struct page *page));
62 static inline void *kmap(struct page *page)
66 if (page < highmem_start_page)
67 return page_address(page);
68 return kmap_high(page);
71 static inline void kunmap(struct page *page)
75 if (page < highmem_start_page)
81 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
82 * gives a more generic (and caching) interface. But kmap_atomic can
83 * be used in IRQ contexts, so in some (very limited) cases we need
86 static inline void *kmap_atomic(struct page *page, enum km_type type)
88 enum fixed_addresses idx;
91 if (page < highmem_start_page)
92 return page_address(page);
94 idx = type + KM_TYPE_NR*smp_processor_id();
95 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
97 if (!pte_none(*(kmap_pte-idx)))
100 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
101 __flush_tlb_one(vaddr);
103 return (void*) vaddr;
106 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
109 unsigned long vaddr = (unsigned long) kvaddr;
110 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
112 if (vaddr < FIXADDR_START) // FIXME
115 if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
119 * force other mappings to Oops if they'll try to access
120 * this pte without first remap it
122 pte_clear(kmap_pte-idx);
123 __flush_tlb_one(vaddr);
127 #endif /* __KERNEL__ */
129 #endif /* _ASM_HIGHMEM_H */