86 lines
2.5 KiB
C
86 lines
2.5 KiB
C
/*
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* fixmap.h: compile-time virtual memory allocation
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1998 Ingo Molnar
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*
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* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
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*/
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#ifndef _ASM_FIXMAP_H
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#define _ASM_FIXMAP_H
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#include <asm/pgtable.h>
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#ifdef CONFIG_HIGHMEM
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#include <linux/threads.h>
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#include <asm/kmap_types.h>
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#endif
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/*
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* Here we define all the compile-time 'special' virtual
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* addresses. The point is to have a constant address at
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* compile time, but to set the physical address only
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* in the boot process. We allocate these special addresses
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* from the start of the consistent memory region upwards.
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* Also this lets us do fail-safe vmalloc(), we
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* can guarantee that these special addresses and
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* vmalloc()-ed addresses never overlap.
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*
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* these 'compile-time allocated' memory buffers are
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* fixed-size 4k pages. (or larger if used with an increment
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* higher than 1) use fixmap_set(idx,phys) to associate
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* physical memory with fixmap indices.
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*/
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enum fixed_addresses {
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#ifdef CONFIG_HIGHMEM
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/* reserved pte's for temporary kernel mappings */
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FIX_KMAP_BEGIN,
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FIX_KMAP_END = FIX_KMAP_BEGIN +
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(KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1,
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#endif
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__end_of_fixed_addresses
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};
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#define FIXADDR_TOP (VMALLOC_START - PAGE_SIZE)
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#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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#define FIXADDR_START ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
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#define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT))
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#define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT)
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#ifndef __ASSEMBLY__
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/*
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* 'index to address' translation. If anyone tries to use the idx
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* directly without translation, we catch the bug with a NULL-deference
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* kernel oops. Illegal ranges of incoming indices are caught too.
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*/
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static __always_inline unsigned long fix_to_virt(const unsigned int idx)
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{
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/* Check if this memory layout is broken because fixmap overlaps page
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* table.
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*/
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BUILD_BUG_ON(FIXADDR_START <
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XCHAL_PAGE_TABLE_VADDR + XCHAL_PAGE_TABLE_SIZE);
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BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
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return __fix_to_virt(idx);
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}
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static inline unsigned long virt_to_fix(const unsigned long vaddr)
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{
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BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
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return __virt_to_fix(vaddr);
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}
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#endif
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#define kmap_get_fixmap_pte(vaddr) \
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pte_offset_kernel( \
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pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
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(vaddr) \
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)
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#endif
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