ftrace/x86: Show trampoline call function in enabled_functions

The file /sys/kernel/debug/tracing/eneabled_functions is used to debug
ftrace function hooks. Add to the output what function is being called
by the trampoline if the arch supports it.

Add support for this feature in x86_64.

Cc: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 20 insertions, 2 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 15f85eac7e95..422e1f8300b1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2952,6 +2952,22 @@ static void t_stop(struct seq_file *m, void *p)
         mutex_unlock(&ftrace_lock);
 }
 
+void * __weak
+arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
+{
+        return NULL;
+}
+
+static void add_trampoline_func(struct seq_file *m, struct ftrace_ops *ops,
+                                struct dyn_ftrace *rec)
+{
+        void *ptr;
+
+        ptr = arch_ftrace_trampoline_func(ops, rec);
+        if (ptr)
+                seq_printf(m, " ->%pS", ptr);
+}
+
 static int t_show(struct seq_file *m, void *v)
 {
         struct ftrace_iterator *iter = m->private;
@@ -2975,19 +2991,21 @@ static int t_show(struct seq_file *m, void *v)
 
         seq_printf(m, "%ps", (void *)rec->ip);
         if (iter->flags & FTRACE_ITER_ENABLED) {
+                struct ftrace_ops *ops = NULL;
+
                 seq_printf(m, " (%ld)%s",
                            ftrace_rec_count(rec),
                            rec->flags & FTRACE_FL_REGS ? " R" : "  ");
                 if (rec->flags & FTRACE_FL_TRAMP_EN) {
-                        struct ftrace_ops *ops;
-
                         ops = ftrace_find_tramp_ops_any(rec);
                         if (ops)
                                 seq_printf(m, "\ttramp: %pS",
                                            (void *)ops->trampoline);
                         else
                                 seq_printf(m, "\ttramp: ERROR!");
+
                 }
+                add_trampoline_func(m, ops, rec);
         }       
 
         seq_printf(m, "\n");