ftrace: Show all tramps registered to a record on ftrace_bug()

When an anomaly is detected in the function call modification code,
ftrace_bug() is called to disable function tracing as well as give any
information that may help debug the problem. Currently, only the first found
trampoline that is attached to the failed record is reported. Instead, show
all trampolines that are hooked to it.

Also, not only show the ops pointer but also report the function it calls.

While at it, add this info to the enabled_functions debug file too.

Signed-off-by: Steven Rostedt <[email protected]>

Author: rostedt

kernel/trace/ftrace.c

@@ -1952,6 +1952,8 @@ static void print_ip_ins(const char *fmt, const unsigned char *p)
 
 static struct ftrace_ops *
 ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
+static struct ftrace_ops *
+ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);
 
 enum ftrace_bug_type ftrace_bug_type;
 const void *ftrace_expected;
@@ -2028,15 +2030,19 @@ void ftrace_bug(int failed, struct dyn_ftrace *rec)
 			rec->flags & FTRACE_FL_REGS ? " R" : "  ");
 		if (rec->flags & FTRACE_FL_TRAMP_EN) {
 			ops = ftrace_find_tramp_ops_any(rec);
-			if (ops)
-				pr_cont("\ttramp: %pS",
-					(void *)ops->trampoline);
-			else
+			if (ops) {
+				do {
+					pr_cont("\ttramp: %pS (%pS)",
+						(void *)ops->trampoline,
+						(void *)ops->func);
+					ops = ftrace_find_tramp_ops_next(rec, ops);
+				} while (ops);
+			} else
 				pr_cont("\ttramp: ERROR!");
 
 		}
 		ip = ftrace_get_addr_curr(rec);
-		pr_cont(" expected tramp: %lx\n", ip);
+		pr_cont("\n expected tramp: %lx\n", ip);
 	}
 }
 
@@ -2178,6 +2184,24 @@ ftrace_find_tramp_ops_any(struct dyn_ftrace *rec)
 	return NULL;
 }
 
+static struct ftrace_ops *
+ftrace_find_tramp_ops_next(struct dyn_ftrace *rec,
+			   struct ftrace_ops *op)
+{
+	unsigned long ip = rec->ip;
+
+	while_for_each_ftrace_op(op) {
+
+		if (!op->trampoline)
+			continue;
+
+		if (hash_contains_ip(ip, op->func_hash))
+			return op;
+	} 
+
+	return NULL;
+}
+
 static struct ftrace_ops *
 ftrace_find_tramp_ops_curr(struct dyn_ftrace *rec)
 {
@@ -3306,10 +3330,14 @@ static int t_show(struct seq_file *m, void *v)
 			   rec->flags & FTRACE_FL_IPMODIFY ? " I" : "  ");
 		if (rec->flags & FTRACE_FL_TRAMP_EN) {
 			ops = ftrace_find_tramp_ops_any(rec);
-			if (ops)
-				seq_printf(m, "\ttramp: %pS",
-					   (void *)ops->trampoline);
-			else
+			if (ops) {
+				do {
+					seq_printf(m, "\ttramp: %pS (%pS)",
+						   (void *)ops->trampoline,
+						   (void *)ops->func);
+					ops = ftrace_find_tramp_ops_next(rec, ops);
+				} while (ops);
+			} else
 				seq_puts(m, "\ttramp: ERROR!");
 
 		}