[PATCH] tracing: fprobe: use ftrace if CONFIG_DYNAMIC_FTRACE_WITH_ARGS

[Menglong Dong <menglong8.dong@gmail.com>]

For now, we will use ftrace for the fprobe if fp->exit_handler not exists
and CONFIG_DYNAMIC_FTRACE_WITH_REGS is enabled.

However, CONFIG_DYNAMIC_FTRACE_WITH_REGS is not supported by some arch,
such as arm. What we need in the fprobe is the function arguments, so we
can use ftrace for fprobe if CONFIG_DYNAMIC_FTRACE_WITH_ARGS is enabled.

Therefore, use ftrace if CONFIG_DYNAMIC_FTRACE_WITH_REGS or
CONFIG_DYNAMIC_FTRACE_WITH_ARGS enabled.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
---
 kernel/trace/fprobe.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index ecd623eef68b..9fad0569f521 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -254,7 +254,11 @@ static inline int __fprobe_kprobe_handler(unsigned long ip, unsigned long parent
 	return ret;
 }
 
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+#if defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) || defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
+#define FPROBE_USE_FTRACE
+#endif
+
+#ifdef FPROBE_USE_FTRACE
 /* ftrace_ops callback, this processes fprobes which have only entry_handler. */
 static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip,
 	struct ftrace_ops *ops, struct ftrace_regs *fregs)
@@ -295,7 +299,7 @@ NOKPROBE_SYMBOL(fprobe_ftrace_entry);
 
 static struct ftrace_ops fprobe_ftrace_ops = {
 	.func	= fprobe_ftrace_entry,
-	.flags	= FTRACE_OPS_FL_SAVE_REGS,
+	.flags	= FTRACE_OPS_FL_SAVE_ARGS,
 };
 static int fprobe_ftrace_active;
 
@@ -349,7 +353,7 @@ static bool fprobe_is_ftrace(struct fprobe *fp)
 {
 	return false;
 }
-#endif
+#endif /* !FPROBE_USE_FTRACE */
 
 /* fgraph_ops callback, this processes fprobes which have exit_handler. */
 static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
@@ -599,7 +603,7 @@ static int fprobe_module_callback(struct notifier_block *nb,
 	if (alist.index > 0) {
 		ftrace_set_filter_ips(&fprobe_graph_ops.ops,
 				      alist.addrs, alist.index, 1, 0);
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+#ifdef FPROBE_USE_FTRACE
 		ftrace_set_filter_ips(&fprobe_ftrace_ops,
 				      alist.addrs, alist.index, 1, 0);
 #endif
-- 
2.51.1