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author | Thomas Gleixner <tglx@linutronix.de> | 2020-11-03 10:27:17 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2020-11-06 23:14:54 +0100 |
commit | 4f8b96cd47b06f1e3ec71c1a3216113efe8dbfb5 (patch) | |
tree | e2024b147f7d55c20c9e3aaf24a4bfe7b22ef60e /include/asm-generic | |
parent | 673afbace459ae6fd8d03bda410e0a9f10438c99 (diff) | |
download | linux-4f8b96cd47b06f1e3ec71c1a3216113efe8dbfb5.tar.gz |
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
Diffstat (limited to 'include/asm-generic')
-rw-r--r-- | include/asm-generic/Kbuild | 1 | ||||
-rw-r--r-- | include/asm-generic/kmap_size.h | 12 |
2 files changed, 13 insertions, 0 deletions
diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild index e78bbb9a07e9..ed62d384fb79 100644 --- a/include/asm-generic/Kbuild +++ b/include/asm-generic/Kbuild @@ -31,6 +31,7 @@ mandatory-y += irq_regs.h mandatory-y += irq_work.h mandatory-y += kdebug.h mandatory-y += kmap_types.h +mandatory-y += kmap_size.h mandatory-y += kprobes.h mandatory-y += linkage.h mandatory-y += local.h diff --git a/include/asm-generic/kmap_size.h b/include/asm-generic/kmap_size.h new file mode 100644 index 000000000000..9d6c7786a645 --- /dev/null +++ b/include/asm-generic/kmap_size.h @@ -0,0 +1,12 @@ +/* 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_HIGHMEM +# define KM_MAX_IDX 33 +#else +# define KM_MAX_IDX 16 +#endif + +#endif |