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 <linux/highmem.h>
  28 #include <asm/kmap_types.h>
  29 #include <asm/tlbflush.h>
  30 #include <asm/page.h>
  31 #include <asm/fixmap.h>
  32
  33 extern pte_t *kmap_pte;
  34 extern pgprot_t kmap_prot;
  35 extern pte_t *pkmap_page_table;
  36
  37 /*
  38  * Right now we initialize only a single pte table. It can be extended
  39  * easily, subsequent pte tables have to be allocated in one physical
  40  * chunk of RAM.
  41  */
  42 /*
  43  * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
  44  * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  45  * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  46  * in case of 16K/64K/256K page sizes.
  47  */
  48 #ifdef CONFIG_PPC_4K_PAGES
  49 #define PKMAP_ORDER     PTE_SHIFT
  50 #else
  51 #define PKMAP_ORDER     9
  52 #endif
  53 #define LAST_PKMAP      (1 << PKMAP_ORDER)
  54 #ifndef CONFIG_PPC_4K_PAGES
  55 #define PKMAP_BASE      (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
  56 #else
  57 #define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
  58 #endif
  59 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  60 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  61 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  62
  63 extern void *kmap_high(struct page *page);
  64 extern void kunmap_high(struct page *page);
  65
  66 static inline void *kmap(struct page *page)
  67 {
  68         might_sleep();
  69         if (!PageHighMem(page))
  70                 return page_address(page);
  71         return kmap_high(page);
  72 }
  73
  74 static inline void kunmap(struct page *page)
  75 {
  76         BUG_ON(in_interrupt());
  77         if (!PageHighMem(page))
  78                 return;
  79         kunmap_high(page);
  80 }
  81
  82 /*
  83  * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
  84  * gives a more generic (and caching) interface. But kmap_atomic can
  85  * be used in IRQ contexts, so in some (very limited) cases we need
  86  * it.
  87  */
  88 static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
  89 {
  90         unsigned int idx;
  91         unsigned long vaddr;
  92
  93         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  94         pagefault_disable();
  95         if (!PageHighMem(page))
  96                 return page_address(page);
  97
  98         debug_kmap_atomic(type);
  99         idx = type + KM_TYPE_NR*smp_processor_id();
 100         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 101 #ifdef CONFIG_DEBUG_HIGHMEM
 102         BUG_ON(!pte_none(*(kmap_pte-idx)));
 103 #endif
 104         __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
 105         local_flush_tlb_page(NULL, vaddr);
 106
 107         return (void*) vaddr;
 108 }
 109
 110 static inline void *kmap_atomic(struct page *page, enum km_type type)
 111 {
 112         return kmap_atomic_prot(page, type, kmap_prot);
 113 }
 114
 115 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
 116 {
 117 #ifdef CONFIG_DEBUG_HIGHMEM
 118         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 119         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 120
 121         if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
 122                 pagefault_enable();
 123                 return;
 124         }
 125
 126         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 127
 128         /*
 129          * force other mappings to Oops if they'll try to access
 130          * this pte without first remap it
 131          */
 132         pte_clear(&init_mm, vaddr, kmap_pte-idx);
 133         local_flush_tlb_page(NULL, vaddr);
 134 #endif
 135         pagefault_enable();
 136 }
 137
 138 static inline struct page *kmap_atomic_to_page(void *ptr)
 139 {
 140         unsigned long idx, vaddr = (unsigned long) ptr;
 141         pte_t *pte;
 142
 143         if (vaddr < FIXADDR_START)
 144                 return virt_to_page(ptr);
 145
 146         idx = virt_to_fix(vaddr);
 147         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 148         return pte_page(*pte);
 149 }
 150
 151 #define flush_cache_kmaps()     flush_cache_all()
 152
 153 #endif /* __KERNEL__ */
 154
 155 #endif /* _ASM_HIGHMEM_H */