mirror of https://gitee.com/openkylin/linux.git
73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
/*
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* High memory support for Xtensa architecture
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*
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* This file is subject to the terms and conditions of the GNU General
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* Public License. See the file "COPYING" in the main directory of
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* this archive for more details.
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*
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* Copyright (C) 2014 Cadence Design Systems Inc.
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*/
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#include <linux/export.h>
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#include <linux/highmem.h>
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#include <asm/tlbflush.h>
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static pte_t *kmap_pte;
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void *kmap_atomic(struct page *page)
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{
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enum fixed_addresses idx;
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unsigned long vaddr;
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int type;
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pagefault_disable();
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if (!PageHighMem(page))
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return page_address(page);
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type = kmap_atomic_idx_push();
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idx = type + KM_TYPE_NR * smp_processor_id();
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vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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#ifdef CONFIG_DEBUG_HIGHMEM
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BUG_ON(!pte_none(*(kmap_pte - idx)));
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#endif
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set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL_EXEC));
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return (void *)vaddr;
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}
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EXPORT_SYMBOL(kmap_atomic);
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void __kunmap_atomic(void *kvaddr)
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{
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int idx, type;
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if (kvaddr >= (void *)FIXADDR_START &&
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kvaddr < (void *)FIXADDR_TOP) {
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type = kmap_atomic_idx();
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idx = type + KM_TYPE_NR * smp_processor_id();
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/*
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* Force other mappings to Oops if they'll try to access this
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* pte without first remap it. Keeping stale mappings around
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* is a bad idea also, in case the page changes cacheability
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* attributes or becomes a protected page in a hypervisor.
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*/
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pte_clear(&init_mm, kvaddr, kmap_pte - idx);
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local_flush_tlb_kernel_range((unsigned long)kvaddr,
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(unsigned long)kvaddr + PAGE_SIZE);
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kmap_atomic_idx_pop();
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}
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pagefault_enable();
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}
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EXPORT_SYMBOL(__kunmap_atomic);
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void __init kmap_init(void)
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{
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unsigned long kmap_vstart;
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/* cache the first kmap pte */
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kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
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kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
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}
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