arch/microblaze/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/init.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/uaccess.h>
  26 #include <asm/fixmap.h>
  27
  28 extern pte_t *kmap_pte;
  29 extern pgprot_t kmap_prot;
  30 extern pte_t *pkmap_page_table;
  31
  32 /*
  33  * Right now we initialize only a single pte table. It can be extended
  34  * easily, subsequent pte tables have to be allocated in one physical
  35  * chunk of RAM.
  36  */
  37 /*
  38  * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
  39  * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  40  * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  41  * in case of 16K/64K/256K page sizes.
  42  */
  43
  44 #define PKMAP_ORDER     PTE_SHIFT
  45 #define LAST_PKMAP      (1 << PKMAP_ORDER)
  46
  47 #define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE * (LAST_PKMAP + 1)) \
  48                                                                 & PMD_MASK)
  49
  50 #define LAST_PKMAP_MASK (LAST_PKMAP - 1)
  51 #define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
  52 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  53
  54 extern void *kmap_high(struct page *page);
  55 extern void kunmap_high(struct page *page);
  56 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  57 extern void __kunmap_atomic(void *kvaddr);
  58
  59 static inline void *kmap(struct page *page)
  60 {
  61         might_sleep();
  62         if (!PageHighMem(page))
  63                 return page_address(page);
  64         return kmap_high(page);
  65 }
  66
  67 static inline void kunmap(struct page *page)
  68 {
  69         BUG_ON(in_interrupt());
  70         if (!PageHighMem(page))
  71                 return;
  72         kunmap_high(page);
  73 }
  74
  75 static inline void *kmap_atomic(struct page *page)
  76 {
  77         return kmap_atomic_prot(page, kmap_prot);
  78 }
  79
  80 #define flush_cache_kmaps()     { flush_icache(); flush_dcache(); }
  81
  82 #endif /* __KERNEL__ */
  83
  84 #endif /* _ASM_HIGHMEM_H */