6555910065
Introduce fixmap area just below the vmalloc region. Use it for atomic mapping of high memory pages. High memory on cores with cache aliasing is not supported and is still to be implemented. Fail build for such configurations for now. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
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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