From 0294b3a702b2b9aea24f2e7b5ee766bc4ea65a68 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 3 Nov 2020 10:27:17 +0100 Subject: [PATCH 028/323] asm-generic: Provide kmap_size.h Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.215-rt107.tar.xz 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 Signed-off-by: Sebastian Andrzej Siewior --- 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 d1300c6e0a471..3114a6da7e561 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 0000000000000..9d6c7786a645f --- /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 -- 2.44.0