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authorThomas Gleixner <tglx@linutronix.de>2020-11-03 10:27:17 +0100
committerThomas Gleixner <tglx@linutronix.de>2020-11-06 23:14:54 +0100
commit4f8b96cd47b06f1e3ec71c1a3216113efe8dbfb5 (patch)
treee2024b147f7d55c20c9e3aaf24a4bfe7b22ef60e /include/asm-generic
parent673afbace459ae6fd8d03bda410e0a9f10438c99 (diff)
downloadlinux-4f8b96cd47b06f1e3ec71c1a3216113efe8dbfb5.tar.bz2
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/Kbuild1
-rw-r--r--include/asm-generic/kmap_size.h12
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