ARCv2: Enable unaligned access in early ASM code

It is currently done in arc_init_IRQ() which might be too late
considering gcc 7.3.1 onwards (GNU 2018.03) generates unaligned
memory accesses by default

Cc: stable@vger.kernel.org #4.4+
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: rewrote changelog]

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
index 8b90d25a15cc..26e33a8b2d18 100644
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -17,6 +17,7 @@
 #include <asm/entry.h>
 #include <asm/arcregs.h>
 #include <asm/cache.h>
+#include <asm/irqflags.h>
 
 .macro CPU_EARLY_SETUP
 
@@ -47,6 +48,15 @@
         sr      r5, [ARC_REG_DC_CTRL]
 
 1:
+
+#ifdef CONFIG_ISA_ARCV2
+        ; Unaligned access is disabled at reset, so re-enable early as
+        ; gcc 7.3.1 (ARC GNU 2018.03) onwards generates unaligned access
+        ; by default
+        lr      r5, [status32]
+        bset    r5, r5, STATUS_AD_BIT
+        kflag   r5
+#endif
 .endm
 
         .section .init.text, "ax",@progbits