arch/powerpc/include/asm/highmem.h

   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 #include <asm/fixmap.h>
  31
  32 extern pte_t *kmap_pte;
  33 extern pgprot_t kmap_prot;
  34 extern 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 /*
  42  * We use one full pte table with 4K pages. And with 16K/64K pages pte
  43  * table covers enough memory (32MB and 512MB resp.) that both FIXMAP
  44  * and PKMAP can be placed in single pte table. We use 1024 pages for
  45  * PKMAP in case of 16K/64K pages.
  46  */
  47 #ifdef CONFIG_PPC_4K_PAGES
  48 #define PKMAP_ORDER     PTE_SHIFT
  49 #else
  50 #define PKMAP_ORDER     10
  51 #endif
  52 #define LAST_PKMAP      (1 << PKMAP_ORDER)
  53 #ifndef CONFIG_PPC_4K_PAGES
  54 #define PKMAP_BASE      (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
  55 #else
  56 #define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
  57 #endif
  58 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  59 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  60 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  61
  62 extern void *kmap_high(struct page *page);
  63 extern void kunmap_high(struct page *page);
  64
  65 static inline void *kmap(struct page *page)
  66 {
  67         might_sleep();
  68         if (!PageHighMem(page))
  69                 return page_address(page);
  70         return kmap_high(page);
  71 }
  72
  73 static inline void kunmap(struct page *page)
  74 {
  75         BUG_ON(in_interrupt());
  76         if (!PageHighMem(page))
  77                 return;
  78         kunmap_high(page);
  79 }
  80
  81 /*
  82  * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
  83  * gives a more generic (and caching) interface. But kmap_atomic can
  84  * be used in IRQ contexts, so in some (very limited) cases we need
  85  * it.
  86  */
  87 static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
  88 {
  89         unsigned int idx;
  90         unsigned long vaddr;
  91
  92         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  93         pagefault_disable();
  94         if (!PageHighMem(page))
  95                 return page_address(page);
  96
  97         idx = type + KM_TYPE_NR*smp_processor_id();
  98         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  99 #ifdef CONFIG_DEBUG_HIGHMEM
 100         BUG_ON(!pte_none(*(kmap_pte-idx)));
 101 #endif
 102         __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
 103         local_flush_tlb_page(NULL, vaddr);
 104
 105         return (void*) vaddr;
 106 }
 107
 108 static inline void *kmap_atomic(struct page *page, enum km_type type)
 109 {
 110         return kmap_atomic_prot(page, type, kmap_prot);
 111 }
 112
 113 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
 114 {
 115 #ifdef CONFIG_DEBUG_HIGHMEM
 116         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 117         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 118
 119         if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
 120                 pagefault_enable();
 121                 return;
 122         }
 123
 124         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 125
 126         /*
 127          * force other mappings to Oops if they'll try to access
 128          * this pte without first remap it
 129          */
 130         pte_clear(&init_mm, vaddr, kmap_pte-idx);
 131         local_flush_tlb_page(NULL, vaddr);
 132 #endif
 133         pagefault_enable();
 134 }
 135
 136 static inline struct page *kmap_atomic_to_page(void *ptr)
 137 {
 138         unsigned long idx, vaddr = (unsigned long) ptr;
 139         pte_t *pte;
 140
 141         if (vaddr < FIXADDR_START)
 142                 return virt_to_page(ptr);
 143
 144         idx = virt_to_fix(vaddr);
 145         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 146         return pte_page(*pte);
 147 }
 148
 149 #define flush_cache_kmaps()     flush_cache_all()
 150
 151 #endif /* __KERNEL__ */
 152
 153 #endif /* _ASM_HIGHMEM_H */