include/asm-i386/highmem.h

   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 adresses.
   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 Terrabyte 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
  18 #ifndef _ASM_HIGHMEM_H
  19 #define _ASM_HIGHMEM_H
  20
  21 #ifdef __KERNEL__
  22
  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>
  28
  29 /* undef for production */
  30 #define HIGHMEM_DEBUG 1
  31
  32 /* declarations for highmem.c */
  33 extern unsigned long highstart_pfn, highend_pfn;
  34
  35 extern pte_t *kmap_pte;
  36 extern pgprot_t kmap_prot;
  37 extern pte_t *pkmap_page_table;
  38
  39 extern void kmap_init(void) __init;
  40
  41 /*
  42  * Right now we initialize only a single pte table. It can be extended
  43  * easily, subsequent pte tables have to be allocated in one physical
  44  * chunk of RAM.
  45  */
  46 #define PKMAP_BASE (0xfe000000UL)
  47 #ifdef CONFIG_X86_PAE
  48 #define LAST_PKMAP 512
  49 #else
  50 #define LAST_PKMAP 1024
  51 #endif
  52 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  53 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  54 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  55
  56 extern void * FASTCALL(kmap_high(struct page *page));
  57 extern void FASTCALL(kunmap_high(struct page *page));
  58
  59 static inline void *kmap(struct page *page)
  60 {
  61         if (in_interrupt())
  62                 BUG();
  63         if (page < highmem_start_page)
  64                 return page_address(page);
  65         return kmap_high(page);
  66 }
  67
  68 static inline void kunmap(struct page *page)
  69 {
  70         if (in_interrupt())
  71                 BUG();
  72         if (page < highmem_start_page)
  73                 return;
  74         kunmap_high(page);
  75 }
  76
  77 /*
  78  * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
  79  * gives a more generic (and caching) interface. But kmap_atomic can
  80  * be used in IRQ contexts, so in some (very limited) cases we need
  81  * it.
  82  */
  83 static inline void *kmap_atomic(struct page *page, enum km_type type)
  84 {
  85         enum fixed_addresses idx;
  86         unsigned long vaddr;
  87
  88         if (page < highmem_start_page)
  89                 return page_address(page);
  90
  91         idx = type + KM_TYPE_NR*smp_processor_id();
  92         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  93 #if HIGHMEM_DEBUG
  94         if (!pte_none(*(kmap_pte-idx)))
  95                 BUG();
  96 #endif
  97         set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
  98         __flush_tlb_one(vaddr);
  99
 100         return (void*) vaddr;
 101 }
 102
 103 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
 104 {
 105 #if HIGHMEM_DEBUG
 106         unsigned long vaddr = (unsigned long) kvaddr;
 107         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 108
 109         if (vaddr < FIXADDR_START) // FIXME
 110                 return;
 111
 112         if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
 113                 BUG();
 114
 115         /*
 116          * force other mappings to Oops if they'll try to access
 117          * this pte without first remap it
 118          */
 119         pte_clear(kmap_pte-idx);
 120         __flush_tlb_one(vaddr);
 121 #endif
 122 }
 123
 124 #endif /* __KERNEL__ */
 125
 126 #endif /* _ASM_HIGHMEM_H */