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      1 /*
      2  * highmem.h: virtual kernel memory mappings for high memory
      3  *
      4  * Used in CONFIG_HIGHMEM systems for memory pages which
      5  * are not addressable by direct kernel virtual addresses.
      6  *
      7  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
      8  *		      Gerhard.Wichert (at) pdb.siemens.de
      9  *
     10  *
     11  * Redesigned the x86 32-bit VM architecture to deal with
     12  * up to 16 Terabyte physical memory. With current x86 CPUs
     13  * we now support up to 64 Gigabytes physical RAM.
     14  *
     15  * Copyright (C) 1999 Ingo Molnar <mingo (at) redhat.com>
     16  */
     17 
     18 #ifndef _ASM_HIGHMEM_H
     19 #define _ASM_HIGHMEM_H
     20 
     21 #ifdef __KERNEL__
     22 
     23 #include <linux/interrupt.h>
     24 #include <linux/threads.h>
     25 #include <asm/kmap_types.h>
     26 #include <asm/tlbflush.h>
     27 #include <asm/paravirt.h>
     28 
     29 /* declarations for highmem.c */
     30 extern unsigned long highstart_pfn, highend_pfn;
     31 
     32 extern pte_t *kmap_pte;
     33 extern pgprot_t kmap_prot;
     34 extern 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 #ifdef CONFIG_X86_PAE
     42 #define LAST_PKMAP 512
     43 #else
     44 #define LAST_PKMAP 1024
     45 #endif
     46 /*
     47  * Ordering is:
     48  *
     49  * FIXADDR_TOP
     50  * 			fixed_addresses
     51  * FIXADDR_START
     52  * 			temp fixed addresses
     53  * FIXADDR_BOOT_START
     54  * 			Persistent kmap area
     55  * PKMAP_BASE
     56  * VMALLOC_END
     57  * 			Vmalloc area
     58  * VMALLOC_START
     59  * high_memory
     60  */
     61 #define PKMAP_BASE ( (FIXADDR_BOOT_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK )
     62 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
     63 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
     64 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
     65 
     66 extern void * FASTCALL(kmap_high(struct page *page));
     67 extern void FASTCALL(kunmap_high(struct page *page));
     68 
     69 void *kmap(struct page *page);
     70 void kunmap(struct page *page);
     71 void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot);
     72 void *kmap_atomic(struct page *page, enum km_type type);
     73 void kunmap_atomic(void *kvaddr, enum km_type type);
     74 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
     75 struct page *kmap_atomic_to_page(void *ptr);
     76 
     77 #ifndef CONFIG_PARAVIRT
     78 #define kmap_atomic_pte(page, type)	kmap_atomic(page, type)
     79 #endif
     80 
     81 #define flush_cache_kmaps()	do { } while (0)
     82 
     83 #endif /* __KERNEL__ */
     84 
     85 #endif /* _ASM_HIGHMEM_H */
     86