ARC: Unaligned access emulation
ARC700 doesn't natively support unaligned access, but can be emulated
-Unaligned Access Exception
-Disassembly at the Fault address to find the exact insn (long/short)
Also per Arnd's comment, we runtime control it using 2 sysctl knobs:
* SYSCTL_ARCH_UNALIGN_ALLOW: Runtime enable/disble
* SYSCTL_ARCH_UNALIGN_NO_WARN: Warn on each emulation attempt
Originally contributed by Tim Yao <tim.yao@amlogic.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Tim Yao <tim.yao@amlogic.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index cde8d3f..f804283 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -336,6 +336,17 @@
This reserved Register R25 to point to Current Task in
kernel mode. This saves memory access for each such access
+
+config ARC_MISALIGN_ACCESS
+ bool "Emulate unaligned memory access (userspace only)"
+ default N
+ select SYSCTL_ARCH_UNALIGN_NO_WARN
+ select SYSCTL_ARCH_UNALIGN_ALLOW
+ help
+ This enables misaligned 16 & 32 bit memory access from user space.
+ Use ONLY-IF-ABS-NECESSARY as it will be very slow and also can hide
+ potential bugs in code
+
config ARC_STACK_NONEXEC
bool "Make stack non-executable"
default n