nds32: Fix the unaligned access handler

If the kernel config 'CONFIG_ALIGNMENT_TRAP' and the file
'/proc/sys/nds32/unaligned_access/enable' are set, the kernel
unaligned access handler does not handle correctly when the
value of immediate field is negative. This commit fixes the
unaligned access handler in kernel.

Signed-off-by: Nickhu <nickhu@andestech.com>
Reviewed-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

arch/nds32/mm/alignment.c

@@ -19,7 +19,7 @@
 #define RA(inst)	(((inst) >> 15) & 0x1FUL)
 #define RB(inst)	(((inst) >> 10) & 0x1FUL)
 #define SV(inst)	(((inst) >> 8) & 0x3UL)
-#define IMM(inst)	(((inst) >> 0) & 0x3FFFUL)
+#define IMM(inst)	(((inst) >> 0) & 0x7FFFUL)
 
 #define RA3(inst)	(((inst) >> 3) & 0x7UL)
 #define RT3(inst)	(((inst) >> 6) & 0x7UL)
@@ -28,6 +28,9 @@
 #define RA5(inst)	(((inst) >> 0) & 0x1FUL)
 #define RT4(inst)	(((inst) >> 5) & 0xFUL)
 
+#define GET_IMMSVAL(imm_value) \
+	(((imm_value >> 14) & 0x1) ? (imm_value - 0x8000) : imm_value)
+
 #define __get8_data(val,addr,err)	\
 	__asm__(					\
 	"1:	lbi.bi	%1, [%2], #1\n"			\
@@ -467,7 +470,7 @@ static inline int do_32(unsigned long inst, struct pt_regs *regs)
 	}
 
 	if (imm)
-		shift = IMM(inst) * len;
+		shift = GET_IMMSVAL(IMM(inst)) * len;
 	else
 		shift = *idx_to_addr(regs, RB(inst)) << SV(inst);