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/interrupt.h>
  26#include <asm/kmap_types.h>
  27#include <asm/tlbflush.h>
  28#include <asm/page.h>
  29#include <asm/fixmap.h>
  30
  31extern pte_t *kmap_pte;
  32extern pgprot_t kmap_prot;
  33extern pte_t *pkmap_page_table;
  34
  35/*
  36 * Right now we initialize only a single pte table. It can be extended
  37 * easily, subsequent pte tables have to be allocated in one physical
  38 * chunk of RAM.
  39 */
  40/*
  41 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
  42 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  43 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  44 * in case of 16K/64K/256K page sizes.
  45 */
  46#ifdef CONFIG_PPC_4K_PAGES
  47#define PKMAP_ORDER     PTE_SHIFT
  48#else
  49#define PKMAP_ORDER     9
  50#endif
  51#define LAST_PKMAP      (1 << PKMAP_ORDER)
  52#ifndef CONFIG_PPC_4K_PAGES
  53#define PKMAP_BASE      (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
  54#else
  55#define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
  56#endif
  57#define LAST_PKMAP_MASK (LAST_PKMAP-1)
  58#define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  59#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  60
  61extern void *kmap_high(struct page *page);
  62extern void kunmap_high(struct page *page);
  63extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  64extern void __kunmap_atomic(void *kvaddr);
  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
  82static inline void *kmap_atomic(struct page *page)
  83{
  84        return kmap_atomic_prot(page, kmap_prot);
  85}
  86
  87static inline struct page *kmap_atomic_to_page(void *ptr)
  88{
  89        unsigned long idx, vaddr = (unsigned long) ptr;
  90        pte_t *pte;
  91
  92        if (vaddr < FIXADDR_START)
  93                return virt_to_page(ptr);
  94
  95        idx = virt_to_fix(vaddr);
  96        pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
  97        return pte_page(*pte);
  98}
  99
 100
 101#define flush_cache_kmaps()     flush_cache_all()
 102
 103#endif /* __KERNEL__ */
 104
 105#endif /* _ASM_HIGHMEM_H */
 106