4f8b96cd47
kmap_types.h is a misnomer because the old atomic MAP based array does not
exist anymore and the whole indirection of architectures including
kmap_types.h is inconinstent and does not allow to provide guard page
debugging for this misfeature.
Add a common header file which defines the mapping stack size for all
architectures. Will be used when converting architectures over to a
generic kmap_local/atomic implementation.
The array size is chosen with the following constraints in mind:
- The deepest nest level in one context is 3 according to code
inspection.
- The worst case nesting for the upcoming reemptible version would be:
2 maps in task context and a fault inside
2 maps in the fault handler
3 maps in softirq
2 maps in interrupt
So a total of 16 is sufficient and probably overestimated.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095857.078043987@linutronix.de
13 lines
260 B
C
13 lines
260 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_GENERIC_KMAP_SIZE_H
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#define _ASM_GENERIC_KMAP_SIZE_H
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/* For debug this provides guard pages between the maps */
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#ifdef CONFIG_DEBUG_HIGHMEM
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# define KM_MAX_IDX 33
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#else
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# define KM_MAX_IDX 16
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#endif
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#endif
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