LXR linux/arch/powerpc/include/asm/highmem.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * highmem.h: virtual kernel memory mappings for high memory
   4 *
   5 * PowerPC version, stolen from the i386 version.
   6 *
   7 * Used in CONFIG_HIGHMEM systems for memory pages which
   8 * are not addressable by direct kernel virtual addresses.
   9 *
  10 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
  11 *                    Gerhard.Wichert@pdb.siemens.de
  12 *
  13 *
  14 * Redesigned the x86 32-bit VM architecture to deal with
  15 * up to 16 Terrabyte physical memory. With current x86 CPUs
  16 * we now support up to 64 Gigabytes physical RAM.
  17 *
  18 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  19 */
  20
  21#ifndef _ASM_HIGHMEM_H
  22#define _ASM_HIGHMEM_H
  23
  24#ifdef __KERNEL__
  25
  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
  32extern pte_t *kmap_pte;
  33extern pgprot_t kmap_prot;
  34extern 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/256K pages pte
  43 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  44 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  45 * in case of 16K/64K/256K page sizes.
  46 */
  47#ifdef CONFIG_PPC_4K_PAGES
  48#define PKMAP_ORDER     PTE_SHIFT
  49#else
  50#define PKMAP_ORDER     9
  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
  62extern void *kmap_high(struct page *page);
  63extern void kunmap_high(struct page *page);
  64extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  65extern void __kunmap_atomic(void *kvaddr);
  66
  67static inline void *kmap(struct page *page)
  68{
  69        might_sleep();
  70        if (!PageHighMem(page))
  71                return page_address(page);
  72        return kmap_high(page);
  73}
  74
  75static inline void kunmap(struct page *page)
  76{
  77        BUG_ON(in_interrupt());
  78        if (!PageHighMem(page))
  79                return;
  80        kunmap_high(page);
  81}
  82
  83static inline void *kmap_atomic(struct page *page)
  84{
  85        return kmap_atomic_prot(page, kmap_prot);
  86}
  87
  88
  89#define flush_cache_kmaps()     flush_cache_all()
  90
  91#endif /* __KERNEL__ */
  92
  93#endif /* _ASM_HIGHMEM_H */
  94