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Linux/arch/microblaze/mm/highmem.c

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  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/export.h>
 25 #include <linux/highmem.h>
 26 
 27 /*
 28  * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
 29  * gives a more generic (and caching) interface. But kmap_atomic can
 30  * be used in IRQ contexts, so in some (very limited) cases we need
 31  * it.
 32  */
 33 #include <asm/tlbflush.h>
 34 
 35 void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 36 {
 37 
 38         unsigned long vaddr;
 39         int idx, type;
 40 
 41         preempt_disable();
 42         pagefault_disable();
 43         if (!PageHighMem(page))
 44                 return page_address(page);
 45 
 46 
 47         type = kmap_atomic_idx_push();
 48         idx = type + KM_TYPE_NR*smp_processor_id();
 49         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 50 #ifdef CONFIG_DEBUG_HIGHMEM
 51         BUG_ON(!pte_none(*(kmap_pte-idx)));
 52 #endif
 53         set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
 54         local_flush_tlb_page(NULL, vaddr);
 55 
 56         return (void *) vaddr;
 57 }
 58 EXPORT_SYMBOL(kmap_atomic_prot);
 59 
 60 void __kunmap_atomic(void *kvaddr)
 61 {
 62         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 63         int type;
 64         unsigned int idx;
 65 
 66         if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
 67                 pagefault_enable();
 68                 preempt_enable();
 69                 return;
 70         }
 71 
 72         type = kmap_atomic_idx();
 73 
 74         idx = type + KM_TYPE_NR * smp_processor_id();
 75 #ifdef CONFIG_DEBUG_HIGHMEM
 76         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 77 #endif
 78         /*
 79          * force other mappings to Oops if they'll try to access
 80          * this pte without first remap it
 81          */
 82         pte_clear(&init_mm, vaddr, kmap_pte-idx);
 83         local_flush_tlb_page(NULL, vaddr);
 84 
 85         kmap_atomic_idx_pop();
 86         pagefault_enable();
 87         preempt_enable();
 88 }
 89 EXPORT_SYMBOL(__kunmap_atomic);
 90 

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