1eb0616c2d
The conversion to the generic kmap_atomic() implementation missed the fact
that xtensa's fixmap works bottom up while all other implementations work
top down. There is no real reason why xtensa needs to work that way.
Cure it by:
- Using the generic fix_to_virt()/virt_to_fix() functions which work top
down
- Adjusting the mapping defines
- Using the generic index calculation for the non cache aliasing case
- Making the cache colour offset reverse so the effective index is correct
While at it, remove the outdated and misleading comment above the fixmap
enum which originates from the initial copy&pasta of this code from i386.
[ Max: Fixed the off by one in the index calculation ]
Fixes: 629ed3f7da ("xtensa/mm/highmem: Switch to generic kmap atomic")
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Link: https://lore.kernel.org/r/20201116193253.23875-1-jcmvbkbc@gmail.com
39 lines
1.1 KiB
C
39 lines
1.1 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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#ifdef CONFIG_HIGHMEM
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#include <linux/threads.h>
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#include <linux/pgtable.h>
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#include <asm/kmap_size.h>
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/* The map slots for temporary mappings via kmap_atomic/local(). */
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enum fixed_addresses {
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FIX_KMAP_BEGIN,
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FIX_KMAP_END = FIX_KMAP_BEGIN +
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(KM_MAX_IDX * NR_CPUS * DCACHE_N_COLORS) - 1,
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__end_of_fixed_addresses
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};
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#define FIXADDR_END (XCHAL_KSEG_CACHED_VADDR - PAGE_SIZE)
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#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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/* Enforce that FIXADDR_START is PMD aligned to handle cache aliasing */
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#define FIXADDR_START ((FIXADDR_END - FIXADDR_SIZE) & PMD_MASK)
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#define FIXADDR_TOP (FIXADDR_START + FIXADDR_SIZE - PAGE_SIZE)
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#include <asm-generic/fixmap.h>
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#endif /* CONFIG_HIGHMEM */
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#endif
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