From: Thomas Gleixner <tglx@linutronix•de>
To: LKML <linux-kernel@vger•kernel.org>
Cc: Juri Lelli <juri.lelli@redhat•com>,
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Andrew Morton <akpm@linux-foundation•org>,
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"David S. Miller" <davem@davemloft•net>,
linux-btrfs@vger•kernel.org, Greentime Hu <green.hu@gmail•com>
Subject: [patch V3 05/37] asm-generic: Provide kmap_size.h
Date: Tue, 03 Nov 2020 10:27:17 +0100 [thread overview]
Message-ID: <20201103095857.078043987@linutronix.de> (raw)
In-Reply-To: 20201103092712.714480842@linutronix.de
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>
---
V3: New patch
---
include/asm-generic/Kbuild | 1 +
include/asm-generic/kmap_size.h | 12 ++++++++++++
2 files changed, 13 insertions(+)
--- 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
--- /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
next prev parent reply other threads:[~2020-11-03 11:02 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 9:27 [patch V3 00/37] mm/highmem: Preemptible variant of kmap_atomic & friends Thomas Gleixner
2020-11-03 9:27 ` [patch V3 01/37] mm/highmem: Un-EXPORT __kmap_atomic_idx() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 02/37] highmem: Remove unused functions Thomas Gleixner
2020-11-03 9:27 ` [patch V3 03/37] fs: Remove asm/kmap_types.h includes Thomas Gleixner
2020-11-03 11:12 ` David Sterba
2020-11-03 9:27 ` [patch V3 04/37] sh/highmem: Remove all traces of unused cruft Thomas Gleixner
2020-11-03 9:27 ` Thomas Gleixner [this message]
2020-11-03 12:25 ` [patch V3 05/37] asm-generic: Provide kmap_size.h Arnd Bergmann
2020-11-03 9:27 ` [patch V3 06/37] highmem: Provide generic variant of kmap_atomic* Thomas Gleixner
2020-11-03 9:27 ` [patch V3 07/37] highmem: Make DEBUG_HIGHMEM functional Thomas Gleixner
2020-11-03 9:27 ` [patch V3 08/37] x86/mm/highmem: Use generic kmap atomic implementation Thomas Gleixner
2020-11-03 9:27 ` [patch V3 09/37] arc/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 10/37] ARM: highmem: Switch to generic kmap atomic Thomas Gleixner
2020-11-12 8:10 ` Marek Szyprowski
2020-11-12 11:03 ` Thomas Gleixner
2020-11-12 11:07 ` Sebastian Andrzej Siewior
2020-11-03 9:27 ` [patch V3 11/37] csky/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 12/37] microblaze/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 13/37] mips/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 14/37] nds32/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 15/37] powerpc/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 16/37] sparc/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 17/37] xtensa/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 18/37] highmem: Get rid of kmap_types.h Thomas Gleixner
2020-11-03 9:27 ` [patch V3 19/37] mm/highmem: Remove the old kmap_atomic cruft Thomas Gleixner
2020-11-03 9:27 ` [patch V3 20/37] io-mapping: Cleanup atomic iomap Thomas Gleixner
2020-11-03 9:27 ` [patch V3 21/37] Documentation/io-mapping: Remove outdated blurb Thomas Gleixner
2020-11-03 9:27 ` [patch V3 22/37] highmem: High implementation details and document API Thomas Gleixner
2020-11-03 17:48 ` Linus Torvalds
2020-11-03 19:00 ` Thomas Gleixner
2020-11-03 9:27 ` [patch V3 23/37] sched: Make migrate_disable/enable() independent of RT Thomas Gleixner
2020-11-03 9:27 ` [patch V3 24/37] sched: highmem: Store local kmaps in task struct Thomas Gleixner
2020-11-03 13:49 ` Thomas Gleixner
2020-11-03 13:51 ` [patch V4 " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 25/37] mm/highmem: Provide kmap_local* Thomas Gleixner
2020-11-03 9:27 ` [patch V3 26/37] io-mapping: Provide iomap_local variant Thomas Gleixner
2020-11-03 9:27 ` [patch V3 27/37] x86/crashdump/32: Simplify copy_oldmem_page() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 28/37] mips/crashdump: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 29/37] ARM: mm: Replace kmap_atomic_pfn() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 30/37] highmem: Remove kmap_atomic_pfn() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 31/37] drm/ttm: Replace kmap_atomic() usage Thomas Gleixner
2020-11-03 9:27 ` [patch V3 32/37] drm/vmgfx: Replace kmap_atomic() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 33/37] highmem: Remove kmap_atomic_prot() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 34/37] drm/qxl: Replace io_mapping_map_atomic_wc() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 35/37] drm/nouveau/device: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 36/37] drm/i915: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 37/37] io-mapping: Remove io_mapping_map_atomic_wc() Thomas Gleixner
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