ftrace: Add ftrace_find_direct_func()

As function_graph tracer modifies the return address to insert a trampoline
to trace the return of a function, it must be aware of a direct caller, as
when it gets called, the function's return address may not be at on the
stack where it expects. It may have to see if that return address points to
the a direct caller and adjust if it is.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index efe3e521aff4..8b37b8105398 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -51,6 +51,7 @@ static inline void early_trace_init(void) { }
 
 struct module;
 struct ftrace_hash;
+struct ftrace_direct_func;
 
 #if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_MODULES) && \
 	defined(CONFIG_DYNAMIC_FTRACE)
@@ -248,6 +249,7 @@ static inline void ftrace_free_mem(struct module *mod, void *start, void *end) {
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 int register_ftrace_direct(unsigned long ip, unsigned long addr);
 int unregister_ftrace_direct(unsigned long ip, unsigned long addr);
+struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr);
 #else
 static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
 {
@@ -257,6 +259,10 @@ static inline int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
 {
 	return -ENODEV;
 }
+static inline struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr)
+{
+	return NULL;
+}
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS