[MIPS] Use conditional traps for BUG_ON on MIPS II and better.

This shaves of around 4kB and a few cycles for the average kernel that
has CONFIG_BUG enabled.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 0ae19e1..2a932ca 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -669,8 +669,6 @@
 	unsigned int opcode, bcode;
 	siginfo_t info;
 
-	die_if_kernel("Break instruction in kernel code", regs);
-
 	if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
 		goto out_sigsegv;
 
@@ -693,6 +691,7 @@
 	switch (bcode) {
 	case BRK_OVERFLOW << 10:
 	case BRK_DIVZERO << 10:
+		die_if_kernel("Break instruction in kernel code", regs);
 		if (bcode == (BRK_DIVZERO << 10))
 			info.si_code = FPE_INTDIV;
 		else
@@ -702,7 +701,11 @@
 		info.si_addr = (void __user *) regs->cp0_epc;
 		force_sig_info(SIGFPE, &info, current);
 		break;
+	case BRK_BUG:
+		die("Kernel bug detected", regs);
+		break;
 	default:
+		die_if_kernel("Break instruction in kernel code", regs);
 		force_sig(SIGTRAP, current);
 	}
 
@@ -715,8 +718,6 @@
 	unsigned int opcode, tcode = 0;
 	siginfo_t info;
 
-	die_if_kernel("Trap instruction in kernel code", regs);
-
 	if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
 		goto out_sigsegv;
 
@@ -733,6 +734,7 @@
 	switch (tcode) {
 	case BRK_OVERFLOW:
 	case BRK_DIVZERO:
+		die_if_kernel("Trap instruction in kernel code", regs);
 		if (tcode == BRK_DIVZERO)
 			info.si_code = FPE_INTDIV;
 		else
@@ -742,7 +744,11 @@
 		info.si_addr = (void __user *) regs->cp0_epc;
 		force_sig_info(SIGFPE, &info, current);
 		break;
+	case BRK_BUG:
+		die("Kernel bug detected", regs);
+		break;
 	default:
+		die_if_kernel("Trap instruction in kernel code", regs);
 		force_sig(SIGTRAP, current);
 	}