ARM: add support to dump the kernel page tables

This patch allows the kernel page tables to be dumped via a debugfs file,
allowing kernel developers to check the layout of the kernel page tables
and the verify the various permissions and type settings.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig.debug

@@ -2,6 +2,18 @@ menu "Kernel hacking"
 
 source "lib/Kconfig.debug"
 
+config ARM_PTDUMP
+	bool "Export kernel pagetable layout to userspace via debugfs"
+	depends on DEBUG_KERNEL
+	select DEBUG_FS
+	---help---
+	  Say Y here if you want to show the kernel pagetable layout in a
+	  debugfs file. This information is only useful for kernel developers
+	  who are working in architecture specific areas of the kernel.
+	  It is probably not a good idea to enable this feature in a production
+	  kernel.
+	  If in doubt, say "N"
+
 config STRICT_DEVMEM
 	bool "Filter access to /dev/mem"
 	depends on MMU