Blackfin arch: Better error handling of unknown exceptions

Better error handling of unknown exceptions, allows userspace to do a
EXCPT n instruction for a not installed exception handler, and the
kernel doesn't crash (like it use to before this).
Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

arch/blackfin/include/asm/traps.h

@@ -59,6 +59,9 @@
 	level "   or a 16-bit register is accessed with a 32-bit instruction.\n"
 #define HWC_x3(level) \
 	"External Memory Addressing Error\n"
+#define EXC_0x04(level) \
+	"Unimplmented exception occured\n" \
+	level " - Maybe you forgot to install a custom exception handler?\n"
 #define HWC_x12(level) \
 	"Performance Monitor Overflow\n"
 #define HWC_x18(level) \
@@ -84,7 +87,7 @@
 	level "   a particular processor implementation.\n"
 #define EXC_0x22(level) \
 	"Illegal instruction combination\n" \
-	level " - See section for multi-issue rules in the ADSP-BF53x Blackfin\n" \
+	level " - See section for multi-issue rules in the Blackfin\n" \
 	level "   Processor Instruction Set Reference.\n"
 #define EXC_0x23(level) \
 	"Data access CPLB protection violation\n" \

arch/blackfin/kernel/traps.c

@@ -301,18 +301,28 @@ asmlinkage void trap_c(struct pt_regs *fp)
 		printk(KERN_NOTICE EXC_0x03(KERN_NOTICE));
 		CHK_DEBUGGER_TRAP_MAYBE();
 		break;
-	/* 0x04 - User Defined, Caught by default */
-	/* 0x05 - User Defined, Caught by default */
-	/* 0x06 - User Defined, Caught by default */
-	/* 0x07 - User Defined, Caught by default */
-	/* 0x08 - User Defined, Caught by default */
-	/* 0x09 - User Defined, Caught by default */
-	/* 0x0A - User Defined, Caught by default */
-	/* 0x0B - User Defined, Caught by default */
-	/* 0x0C - User Defined, Caught by default */
-	/* 0x0D - User Defined, Caught by default */
-	/* 0x0E - User Defined, Caught by default */
-	/* 0x0F - User Defined, Caught by default */
+	/* 0x04 - User Defined */
+	/* 0x05 - User Defined */
+	/* 0x06 - User Defined */
+	/* 0x07 - User Defined */
+	/* 0x08 - User Defined */
+	/* 0x09 - User Defined */
+	/* 0x0A - User Defined */
+	/* 0x0B - User Defined */
+	/* 0x0C - User Defined */
+	/* 0x0D - User Defined */
+	/* 0x0E - User Defined */
+	/* 0x0F - User Defined */
+	/*
+	 * If we got here, it is most likely that someone was trying to use a
+	 * custom exception handler, and it is not actually installed properly
+	 */
+	case VEC_EXCPT04 ... VEC_EXCPT15:
+		info.si_code = ILL_ILLPARAOP;
+		sig = SIGILL;
+		printk(KERN_NOTICE EXC_0x04(KERN_NOTICE));
+		CHK_DEBUGGER_TRAP_MAYBE();
+		break;
 	/* 0x10 HW Single step, handled here */
 	case VEC_STEP:
 		info.si_code = TRAP_STEP;
@@ -507,9 +517,14 @@ asmlinkage void trap_c(struct pt_regs *fp)
 		}
 		CHK_DEBUGGER_TRAP_MAYBE();
 		break;
+	/*
+	 * We should be handling all known exception types above,
+	 * if we get here we hit a reserved one, so panic
+	 */
 	default:
-		info.si_code = TRAP_ILLTRAP;
-		sig = SIGTRAP;
+		oops_in_progress = 1;
+		info.si_code = ILL_ILLPARAOP;
+		sig = SIGILL;
 		printk(KERN_EMERG "Caught Unhandled Exception, code = %08lx\n",
 			(fp->seqstat & SEQSTAT_EXCAUSE));
 		CHK_DEBUGGER_TRAP_MAYBE();