ARM: implement CONFIG_STRICT_DEVMEM by disabling access to RAM via /dev/mem
There are very few legitimate use cases, if any, for directly accessing
system RAM through /dev/mem. So let's mimic what they do on x86 and
forbid it when CONFIG_STRICT_DEVMEM is turned on.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 91344af..c29fb38 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -2,6 +2,20 @@
source "lib/Kconfig.debug"
+config STRICT_DEVMEM
+ bool "Filter access to /dev/mem"
+ depends on MMU
+ ---help---
+ If this option is disabled, you allow userspace (root) access to all
+ of memory, including kernel and userspace memory. Accidental
+ access to this is obviously disastrous, but specific access can
+ be used by people debugging the kernel.
+
+ If this option is switched on, the /dev/mem file only allows
+ userspace access to memory mapped peripherals.
+
+ If in doubt, say Y.
+
# RMK wants arm kernels compiled with frame pointers or stack unwinding.
# If you know what you are doing and are willing to live without stack
# traces, you can get a slightly smaller kernel by setting this option to