arch/powerpc/include/asm/highmem.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * highmem.h: virtual kernel memory mappings for high memory
   4  *
   5  * PowerPC version, stolen from the i386 version.
   6  *
   7  * Used in CONFIG_HIGHMEM systems for memory pages which
   8  * are not addressable by direct kernel virtual addresses.
   9  *
  10  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
  11  *                    Gerhard.Wichert@pdb.siemens.de
  12  *
  13  *
  14  * Redesigned the x86 32-bit VM architecture to deal with
  15  * up to 16 Terrabyte physical memory. With current x86 CPUs
  16  * we now support up to 64 Gigabytes physical RAM.
  17  *
  18  * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  19  */
  20
  21 #ifndef _ASM_HIGHMEM_H
  22 #define _ASM_HIGHMEM_H
  23
  24 #ifdef __KERNEL__
  25
  26 #include <linux/interrupt.h>
  27 #include <asm/kmap_types.h>
  28 #include <asm/cacheflush.h>
  29 #include <asm/page.h>
  30 #include <asm/fixmap.h>
  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 /*
  42  * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
  43  * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  44  * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  45  * in case of 16K/64K/256K page sizes.
  46  */
  47 #ifdef CONFIG_PPC_4K_PAGES
  48 #define PKMAP_ORDER     PTE_SHIFT
  49 #else
  50 #define PKMAP_ORDER     9
  51 #endif
  52 #define LAST_PKMAP      (1 << PKMAP_ORDER)
  53 #ifndef CONFIG_PPC_4K_PAGES
  54 #define PKMAP_BASE      (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
  55 #else
  56 #define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
  57 #endif
  58 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  59 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  60 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  61
  62 extern void *kmap_high(struct page *page);
  63 extern void kunmap_high(struct page *page);
  64 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  65 extern void __kunmap_atomic(void *kvaddr);
  66
  67 static inline void *kmap(struct page *page)
  68 {
  69         might_sleep();
  70         if (!PageHighMem(page))
  71                 return page_address(page);
  72         return kmap_high(page);
  73 }
  74
  75 static inline void kunmap(struct page *page)
  76 {
  77         BUG_ON(in_interrupt());
  78         if (!PageHighMem(page))
  79                 return;
  80         kunmap_high(page);
  81 }
  82
  83 static inline void *kmap_atomic(struct page *page)
  84 {
  85         return kmap_atomic_prot(page, kmap_prot);
  86 }
  87
  88
  89 #define flush_cache_kmaps()     flush_cache_all()
  90
  91 #endif /* __KERNEL__ */
  92
  93 #endif /* _ASM_HIGHMEM_H */