LXR linux/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
  33extern pte_t *kmap_pte;
  34extern pgprot_t kmap_prot;
  35extern 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
  63extern void *kmap_high(struct page *page);
  64extern void kunmap_high(struct page *page);
  65
  66static 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
  74static 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 */
  88static 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
 110static inline void *kmap_atomic(struct page *page, enum km_type type)
 111{
 112        return kmap_atomic_prot(page, type, kmap_prot);
 113}
 114
 115static 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
 138static 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 */
 156