2 * highmem.h: virtual kernel memory mappings for high memory
4 * PowerPC version, stolen from the i386 version.
6 * Used in CONFIG_HIGHMEM systems for memory pages which
7 * are not addressable by direct kernel virtual addresses.
9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
10 * Gerhard.Wichert@pdb.siemens.de
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.
17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
20 #ifndef _ASM_HIGHMEM_H
21 #define _ASM_HIGHMEM_H
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <asm/kmap_types.h>
28 #include <asm/pgtable.h>
30 /* undef for production */
31 #define HIGHMEM_DEBUG 1
33 extern pte_t *kmap_pte;
34 extern pgprot_t kmap_prot;
35 extern pte_t *pkmap_page_table;
37 extern void kmap_init(void) __init;
40 * Right now we initialize only a single pte table. It can be extended
41 * easily, subsequent pte tables have to be allocated in one physical
44 #define PKMAP_BASE CONFIG_HIGHMEM_START
45 #define LAST_PKMAP PTRS_PER_PTE
46 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
47 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
48 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
50 #define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL)
52 extern void *kmap_high(struct page *page, int nonblock);
53 extern void kunmap_high(struct page *page);
55 #define kmap(page) __kmap(page, 0)
56 #define kmap_nonblock(page) __kmap(page, 1)
58 static inline void *__kmap(struct page *page, int nonblock)
62 if (page < highmem_start_page)
63 return page_address(page);
64 return kmap_high(page, nonblock);
67 static inline void kunmap(struct page *page)
71 if (page < highmem_start_page)
77 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
78 * gives a more generic (and caching) interface. But kmap_atomic can
79 * be used in IRQ contexts, so in some (very limited) cases we need
82 static inline void *kmap_atomic(struct page *page, enum km_type type)
87 if (page < highmem_start_page)
88 return page_address(page);
90 idx = type + KM_TYPE_NR*smp_processor_id();
91 vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE;
93 if (!pte_none(*(kmap_pte+idx)))
96 set_pte(kmap_pte+idx, mk_pte(page, kmap_prot));
97 flush_tlb_page(0, vaddr);
102 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
105 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
106 unsigned int idx = type + KM_TYPE_NR*smp_processor_id();
108 if (vaddr < KMAP_FIX_BEGIN) // FIXME
111 if (vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE)
115 * force other mappings to Oops if they'll try to access
116 * this pte without first remap it
118 pte_clear(kmap_pte+idx);
119 flush_tlb_page(0, vaddr);
123 #endif /* __KERNEL__ */
125 #endif /* _ASM_HIGHMEM_H */