45890f6d34
Implement kmap* API for ARC. This enables - permanent kernel maps (pkmaps): :kmap() API - fixmap : kmap_atomic() We use a very simple/uniform approach for both (unlike some of the other arches). So fixmap doesn't use the customary compile time address stuff. The important semantic is sleep'ability (pkmap) vs. not (fixmap) which the API guarantees. Note that this patch only enables highmem for subsequent PAE40 support as there is no real highmem for ARC in pure 32-bit paradigm as explained below. ARC has 2:2 address split of the 32-bit address space with lower half being translated (virtual) while upper half unstranslated (0x8000_0000 to 0xFFFF_FFFF). kernel itself is linked at base of unstranslated space (i.e. 0x8000_0000 onwards), which is mapped to say DDR 0x0 by external Bus Glue logic (outside the core). So kernel can potentially access 1.75G worth of memory directly w/o need for highmem. (the top 256M is taken by uncached peripheral space from 0xF000_0000 to 0xFFFF_FFFF) In PAE40, hardware can address memory beyond 4G (0x1_0000_0000) while the logical/virtual addresses remain 32-bits. Thus highmem is required for kernel proper to be able to access these pages for it's own purposes (user space is agnostic to this anyways). Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*
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* Copyright (C) 2015 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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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 CONFIG_HIGHMEM
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#include <uapi/asm/page.h>
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#include <asm/kmap_types.h>
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/* start after vmalloc area */
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#define FIXMAP_BASE (PAGE_OFFSET - FIXMAP_SIZE - PKMAP_SIZE)
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#define FIXMAP_SIZE PGDIR_SIZE /* only 1 PGD worth */
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#define KM_TYPE_NR ((FIXMAP_SIZE >> PAGE_SHIFT)/NR_CPUS)
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#define FIXMAP_ADDR(nr) (FIXMAP_BASE + ((nr) << PAGE_SHIFT))
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/* start after fixmap area */
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#define PKMAP_BASE (FIXMAP_BASE + FIXMAP_SIZE)
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#define PKMAP_SIZE PGDIR_SIZE
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#define LAST_PKMAP (PKMAP_SIZE >> PAGE_SHIFT)
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#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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#define PKMAP_NR(virt) (((virt) - PKMAP_BASE) >> PAGE_SHIFT)
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#define kmap_prot PAGE_KERNEL
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#include <asm/cacheflush.h>
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extern void *kmap(struct page *page);
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extern void *kmap_high(struct page *page);
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extern void *kmap_atomic(struct page *page);
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extern void __kunmap_atomic(void *kvaddr);
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extern void kunmap_high(struct page *page);
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extern void kmap_init(void);
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static inline void flush_cache_kmaps(void)
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{
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flush_cache_all();
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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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#endif
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#endif
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