linux/include/asm-generic/kmap_size.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_GENERIC_KMAP_SIZE_H
#define _ASM_GENERIC_KMAP_SIZE_H

/* For debug this provides guard pages between the maps */
#ifdef CONFIG_DEBUG_KMAP_LOCAL
# define KM_MAX_IDX	33
#else
# define KM_MAX_IDX	16
#endif

#endif
asm-generic: Provide kmap_size.h 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 2020-11-03 09:27:17 +00:00			`/* SPDX-License-Identifier: GPL-2.0 */`
			`#ifndef _ASM_GENERIC_KMAP_SIZE_H`
			`#define _ASM_GENERIC_KMAP_SIZE_H`

			`/* For debug this provides guard pages between the maps */`
mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL CONFIG_KMAP_LOCAL can be enabled by x86/32bit even if CONFIG_HIGHMEM is not enabled for temporary MMIO space mappings. Provide it as a seperate config option which depends on CONFIG_KMAP_LOCAL and let CONFIG_DEBUG_HIGHMEM select it. This won't increase the debug coverage of this significantly but it paves the way to do so. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20201118204006.869487226@linutronix.de 2020-11-18 19:48:39 +00:00			`#ifdef CONFIG_DEBUG_KMAP_LOCAL`
asm-generic: Provide kmap_size.h 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 2020-11-03 09:27:17 +00:00			`# define KM_MAX_IDX 33`
			`#else`
			`# define KM_MAX_IDX 16`
			`#endif`

			`#endif`