xtensa: noMMU: allow handling protection faults
Many xtensa CPU cores without full MMU still have memory protection
features capable of raising exceptions for invalid instruction
fetches/data access. Allow handling such exceptions. This improves
behavior of processes that pass invalid memory pointers to syscalls in
noMMU configs: in case of exception the kernel instead of killing the
process is now able to return -EINVAL from a syscall.
Introduce CONFIG_PFAULT that controls whether protection fault code is
enabled and register handlers for common memory protection exceptions
when it is enabled.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index bd113bc..bca2763 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -79,6 +79,7 @@
config MMU
def_bool n
+ select PFAULT
config HAVE_XTENSA_GPIO32
def_bool n
@@ -178,6 +179,16 @@
If unsure, say N.
+config PFAULT
+ bool "Handle protection faults" if EXPERT && !MMU
+ default y
+ help
+ Handle protection faults. MMU configurations must enable it.
+ noMMU configurations may disable it if used memory map never
+ generates protection faults or faults are always fatal.
+
+ If unsure, say Y.
+
config XTENSA_UNALIGNED_USER
bool "Unaligned memory access in user space"
help
