85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* highmem.h: virtual kernel memory mappings for high memory
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*
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* Used in CONFIG_HIGHMEM systems for memory pages which
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* are not addressable by direct kernel virtual addresses.
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*
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* Copyright (C) 1999 Gerhard Wichert, Siemens AG
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* Gerhard.Wichert@pdb.siemens.de
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*
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*
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* Redesigned the x86 32-bit VM architecture to deal with
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* up to 16 Terabyte physical memory. With current x86 CPUs
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* we now support up to 64 Gigabytes physical RAM.
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*
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* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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*/
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#ifndef _ASM_HIGHMEM_H
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#define _ASM_HIGHMEM_H
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#ifdef __KERNEL__
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/uaccess.h>
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#include <asm/fixmap.h>
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extern pte_t *kmap_pte;
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extern pgprot_t kmap_prot;
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extern pte_t *pkmap_page_table;
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/*
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* Right now we initialize only a single pte table. It can be extended
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* easily, subsequent pte tables have to be allocated in one physical
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* chunk of RAM.
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*/
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/*
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* We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
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* table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
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* and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
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* in case of 16K/64K/256K page sizes.
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*/
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#define PKMAP_ORDER PTE_SHIFT
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#define LAST_PKMAP (1 << PKMAP_ORDER)
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#define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE * (LAST_PKMAP + 1)) \
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& PMD_MASK)
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#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
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#define PKMAP_NR(virt) ((virt - PKMAP_BASE) >> PAGE_SHIFT)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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extern void *kmap_high(struct page *page);
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extern void kunmap_high(struct page *page);
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extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
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extern void __kunmap_atomic(void *kvaddr);
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static inline void *kmap(struct page *page)
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{
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might_sleep();
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if (!PageHighMem(page))
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return page_address(page);
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return kmap_high(page);
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}
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static inline void kunmap(struct page *page)
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{
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BUG_ON(in_interrupt());
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if (!PageHighMem(page))
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return;
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kunmap_high(page);
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}
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static inline void *kmap_atomic(struct page *page)
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{
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return kmap_atomic_prot(page, kmap_prot);
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}
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#define flush_cache_kmaps() { flush_icache(); flush_dcache(); }
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#endif /* __KERNEL__ */
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#endif /* _ASM_HIGHMEM_H */
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