arch/powerpc/mm/highmem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * highmem.c: 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  * Reworked for PowerPC by various contributors. Moved from
  21  * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
  22  */
  23
  24 #include <linux/highmem.h>
  25 #include <linux/module.h>
  26
  27 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
  28 {
  29         unsigned long vaddr;
  30         int idx, type;
  31
  32         type = kmap_atomic_idx_push();
  33         idx = type + KM_TYPE_NR*smp_processor_id();
  34         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  35         WARN_ON(IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !pte_none(*(kmap_pte - idx)));
  36         __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
  37         local_flush_tlb_page(NULL, vaddr);
  38
  39         return (void*) vaddr;
  40 }
  41 EXPORT_SYMBOL(kmap_atomic_high_prot);
  42
  43 void kunmap_atomic_high(void *kvaddr)
  44 {
  45         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  46
  47         if (vaddr < __fix_to_virt(FIX_KMAP_END))
  48                 return;
  49
  50         if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
  51                 int type = kmap_atomic_idx();
  52                 unsigned int idx;
  53
  54                 idx = type + KM_TYPE_NR * smp_processor_id();
  55                 WARN_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  56
  57                 /*
  58                  * force other mappings to Oops if they'll try to access
  59                  * this pte without first remap it
  60                  */
  61                 pte_clear(&init_mm, vaddr, kmap_pte-idx);
  62                 local_flush_tlb_page(NULL, vaddr);
  63         }
  64
  65         kmap_atomic_idx_pop();
  66 }
  67 EXPORT_SYMBOL(kunmap_atomic_high);