Messages in this thread Patch in this message | | | Date | Fri, 06 Nov 2020 23:27:26 -0000 | From | "tip-bot2 for Thomas Gleixner" <> | Subject | [tip: core/mm] asm-generic: Provide kmap_size.h |
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The following commit has been merged into the core/mm branch of tip:
Commit-ID: 4f8b96cd47b06f1e3ec71c1a3216113efe8dbfb5 Gitweb: https://git.kernel.org/tip/4f8b96cd47b06f1e3ec71c1a3216113efe8dbfb5 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Tue, 03 Nov 2020 10:27:17 +01:00 Committer: Thomas Gleixner <tglx@linutronix.de> CommitterDate: Fri, 06 Nov 2020 23:14:54 +01:00
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
--- include/asm-generic/Kbuild | 1 + include/asm-generic/kmap_size.h | 12 ++++++++++++ 2 files changed, 13 insertions(+) create mode 100644 include/asm-generic/kmap_size.h
diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild index e78bbb9..ed62d38 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 0000000..9d6c778 --- /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
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