From 0e91a0c6984c837a7c6760e3f28e8e1c532abf87 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 18 Nov 2020 20:48:40 +0100 Subject: mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP CONFIG_DEBUG_KMAP_LOCAL, which is selected by CONFIG_DEBUG_HIGHMEM is only providing guard pages, but does not provide a mechanism to enforce the usage of the kmap_local() infrastructure. Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP which forces the temporary mapping even for lowmem pages. This needs to be a seperate config switch because this only works on architectures which do not have cache aliasing problems. Suggested-by: Linus Torvalds Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20201118204007.028261233@linutronix.de --- lib/Kconfig.debug | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index f24fa158f9db..e952f892f047 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -856,9 +856,23 @@ config DEBUG_KMAP_LOCAL This option enables additional error checking for the kmap_local infrastructure. Disable for production use. +config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP + bool + +config DEBUG_KMAP_LOCAL_FORCE_MAP + bool "Enforce kmap_local temporary mappings" + depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP + select KMAP_LOCAL + select DEBUG_KMAP_LOCAL + help + This option enforces temporary mappings through the kmap_local + mechanism for non-highmem pages and on non-highmem systems. + Disable this for production systems! + config DEBUG_HIGHMEM bool "Highmem debugging" depends on DEBUG_KERNEL && HIGHMEM + select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP select DEBUG_KMAP_LOCAL help This option enables additional error checking for high memory -- cgit v1.2.3