MIPS: microMIPS: Support handling of delay slots.

Add logic needed to properly calculate exceptions for delay slots
when in microMIPS mode.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
diff --git a/arch/mips/include/asm/branch.h b/arch/mips/include/asm/branch.h
index 888766a..40bb9eb 100644
--- a/arch/mips/include/asm/branch.h
+++ b/arch/mips/include/asm/branch.h
@@ -11,6 +11,13 @@
 #include <asm/ptrace.h>
 #include <asm/inst.h>
 
+extern int __isa_exception_epc(struct pt_regs *regs);
+extern int __compute_return_epc(struct pt_regs *regs);
+extern int __compute_return_epc_for_insn(struct pt_regs *regs,
+					 union mips_instruction insn);
+extern int __microMIPS_compute_return_epc(struct pt_regs *regs);
+
+
 static inline int delay_slot(struct pt_regs *regs)
 {
 	return regs->cp0_cause & CAUSEF_BD;
@@ -18,20 +25,25 @@
 
 static inline unsigned long exception_epc(struct pt_regs *regs)
 {
-	if (!delay_slot(regs))
+	if (likely(!delay_slot(regs)))
 		return regs->cp0_epc;
 
+	if (get_isa16_mode(regs->cp0_epc))
+		return __isa_exception_epc(regs);
+
 	return regs->cp0_epc + 4;
 }
 
 #define BRANCH_LIKELY_TAKEN 0x0001
 
-extern int __compute_return_epc(struct pt_regs *regs);
-extern int __compute_return_epc_for_insn(struct pt_regs *regs,
-					 union mips_instruction insn);
-
 static inline int compute_return_epc(struct pt_regs *regs)
 {
+	if (get_isa16_mode(regs->cp0_epc)) {
+		if (cpu_has_mmips)
+			return __microMIPS_compute_return_epc(regs);
+		return regs->cp0_epc;
+	}
+
 	if (!delay_slot(regs)) {
 		regs->cp0_epc += 4;
 		return 0;