arch/x86/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
  19 #ifndef _ASM_X86_HIGHMEM_H
  20 #define _ASM_X86_HIGHMEM_H
  21
  22 #ifdef __KERNEL__
  23
  24 #include <linux/interrupt.h>
  25 #include <linux/threads.h>
  26 #include <asm/kmap_types.h>
  27 #include <asm/tlbflush.h>
  28 #include <asm/paravirt.h>
  29 #include <asm/fixmap.h>
  30
  31 /* declarations for highmem.c */
  32 extern unsigned long highstart_pfn, highend_pfn;
  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 /*
  40  * Ordering is:
  41  *
  42  * high memory on:                                    high_memory off:
  43  *    FIXADDR_TOP                                        FIXADDR_TOP
  44  *        fixed addresses                                    fixed addresses
  45  *    FIXADDR_START                                      FIXADDR_START
  46  *        temp fixed addresses/persistent kmap area      VMALLOC_END
  47  *    PKMAP_BASE                                             temp fixed addresses/vmalloc area
  48  *    VMALLOC_END                                        VMALLOC_START
  49  *        vmalloc area                                   high_memory
  50  *    VMALLOC_START
  51  *    high_memory
  52  *
  53  * The temp fixed area is only used during boot for early_ioremap(), and
  54  * it is unused when the ioremap() is functional. vmalloc/pkmap area become
  55  * available after early boot so the temp fixed area is available for re-use.
  56  */
  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
  61 void *kmap_atomic_pfn(unsigned long pfn);
  62 void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot);
  63
  64 #define flush_cache_kmaps()     do { } while (0)
  65
  66 extern void add_highpages_with_active_regions(int nid, unsigned long start_pfn,
  67                                         unsigned long end_pfn);
  68
  69 #endif /* __KERNEL__ */
  70
  71 #endif /* _ASM_X86_HIGHMEM_H */