text: /* SPDX-License-Identifier: GPL-2.0 */
  /*
   * highmem.h: virtual kernel memory mappings for high memory
   *
   * Used in CONFIG_HIGHMEM systems for memory pages which
   * are not addressable by direct kernel virtual addresses.
   *
   * Copyright (C) 1999 Gerhard Wichert, Siemens AG
   *		      Gerhard.Wichert@pdb.siemens.de
   *
   *
   * Redesigned the x86 32-bit VM architecture to deal with
   * up to 16 Terabyte physical memory. With current x86 CPUs
   * we now support up to 64 Gigabytes physical RAM.
   *
   * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
   */
  
  #ifndef _ASM_X86_HIGHMEM_H
  #define _ASM_X86_HIGHMEM_H
  
  #ifdef __KERNEL__
  
  #include <linux/interrupt.h>
  #include <linux/threads.h>
  #include <asm/kmap_types.h>
  #include <asm/tlbflush.h>
  #include <asm/paravirt.h>
  #include <asm/fixmap.h>
  
  /* declarations for highmem.c */
  extern unsigned long highstart_pfn, highend_pfn;
  
  /*
   * Right now we initialize only a single pte table. It can be extended
   * easily, subsequent pte tables have to be allocated in one physical
   * chunk of RAM.
   */
  /*
   * Ordering is:
   *
   * high memory on:			              high_memory off:
   *    FIXADDR_TOP                                        FIXADDR_TOP
   *        fixed addresses                                    fixed addresses
   *    FIXADDR_START                                      FIXADDR_START
   *        temp fixed addresses/persistent kmap area      VMALLOC_END
   *    PKMAP_BASE                                             temp fixed addresses/vmalloc area
   *    VMALLOC_END                                        VMALLOC_START
   *        vmalloc area                                   high_memory
   *    VMALLOC_START
   *    high_memory
   *
   * The temp fixed area is only used during boot for early_ioremap(), and
   * it is unused when the ioremap() is functional. vmalloc/pkmap area become
   * available after early boot so the temp fixed area is available for re-use.
   */
  #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  
  extern void *kmap_high(struct page *page);
  extern void kunmap_high(struct page *page);
  
  void *kmap(struct page *page);
  void kunmap(struct page *page);
  
  void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  void *kmap_atomic(struct page *page);
  void __kunmap_atomic(void *kvaddr);
  void *kmap_atomic_pfn(unsigned long pfn);
  void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot);
  
  #define flush_cache_kmaps()	do { } while (0)
  
  extern void add_highpages_with_active_regions(int nid, unsigned long start_pfn,
  					unsigned long end_pfn);
  
  #endif /* __KERNEL__ */
  
  #endif /* _ASM_X86_HIGHMEM_H */
  