arch/mips/include/asm/highmem.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * highmem.h: virtual kernel memory mappings for high memory
   4  *
   5  * Used in CONFIG_HIGHMEM systems for memory pages which
   6  * are not addressable by direct kernel virtual addresses.
   7  *
   8  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
   9  *                    Gerhard.Wichert@pdb.siemens.de
  10  *
  11  *
  12  * Redesigned the x86 32-bit VM architecture to deal with
  13  * up to 16 Terabyte physical memory. With current x86 CPUs
  14  * we now support up to 64 Gigabytes physical RAM.
  15  *
  16  * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  17  */
  18 #ifndef _ASM_HIGHMEM_H
  19 #define _ASM_HIGHMEM_H
  20
  21 #ifdef __KERNEL__
  22
  23 #include <linux/bug.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/uaccess.h>
  26 #include <asm/cpu-features.h>
  27 #include <asm/kmap_types.h>
  28
  29 /* declarations for highmem.c */
  30 extern unsigned long highstart_pfn, highend_pfn;
  31
  32 extern pte_t *pkmap_page_table;
  33
  34 /*
  35  * Right now we initialize only a single pte table. It can be extended
  36  * easily, subsequent pte tables have to be allocated in one physical
  37  * chunk of RAM.
  38  */
  39 #ifdef CONFIG_PHYS_ADDR_T_64BIT
  40 #define LAST_PKMAP 512
  41 #else
  42 #define LAST_PKMAP 1024
  43 #endif
  44
  45 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  46 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  47 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  48
  49 extern void * kmap_high(struct page *page);
  50 extern void kunmap_high(struct page *page);
  51
  52 extern void *kmap(struct page *page);
  53 extern void kunmap(struct page *page);
  54 extern void *kmap_atomic(struct page *page);
  55 extern void __kunmap_atomic(void *kvaddr);
  56 extern void *kmap_atomic_pfn(unsigned long pfn);
  57
  58 #define flush_cache_kmaps()     BUG_ON(cpu_has_dc_aliases)
  59
  60 extern void kmap_init(void);
  61
  62 #define kmap_prot PAGE_KERNEL
  63
  64 #endif /* __KERNEL__ */
  65
  66 #endif /* _ASM_HIGHMEM_H */