s390/test_unwind: print verbose unwinding results

Add stack name, sp and reliable information into test unwinding
results. Also consider ip outside of kernel text as failure if the
state is reported reliable.
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/dumpstack.c

@@ -38,6 +38,7 @@ const char *stack_type_name(enum stack_type type)
 		return "unknown";
 	}
 }
+EXPORT_SYMBOL_GPL(stack_type_name);
 
 static inline bool in_stack(unsigned long sp, struct stack_info *info,
 			    enum stack_type type, unsigned long low,

arch/s390/lib/test_unwind.c

@@ -56,11 +56,19 @@ static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
 		unsigned long addr = unwind_get_return_address(&state);
 		char sym[KSYM_SYMBOL_LEN];
 
-		if (!addr || frame_count == max_frames)
+		if (frame_count++ == max_frames)
 			break;
+		if (state.reliable && !addr) {
+			pr_err("unwind state reliable but addr is 0\n");
+			return -EINVAL;
+		}
 		sprint_symbol(sym, addr);
 		if (bt_pos < BT_BUF_SIZE) {
-			bt_pos += snprintf(bt + bt_pos, BT_BUF_SIZE - bt_pos, "%s\n", sym);
+			bt_pos += snprintf(bt + bt_pos, BT_BUF_SIZE - bt_pos,
+					   state.reliable ? " [%-7s%px] %pSR\n" :
+							    "([%-7s%px] %pSR)\n",
+					   stack_type_name(state.stack_info.type),
+					   (void *)state.sp, (void *)state.ip);
 			if (bt_pos >= BT_BUF_SIZE)
 				pr_err("backtrace buffer is too small\n");
 		}