ftrace: Remove the legacy _ftrace_direct API

This API relies on a single global ops, used for all direct calls
registered with it. However, to implement arm64 direct calls, we need
each ops to point to a single direct call trampoline.

Link: https://lkml.kernel.org/r/20230321140424.345218-4-revest@chromium.org

Signed-off-by: Florent Revest <revest@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

include/linux/ftrace.h

@@ -397,14 +397,6 @@ struct ftrace_func_entry {
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 extern int ftrace_direct_func_count;
-int register_ftrace_direct(unsigned long ip, unsigned long addr);
-int unregister_ftrace_direct(unsigned long ip, unsigned long addr);
-int modify_ftrace_direct(unsigned long ip, unsigned long old_addr, unsigned long new_addr);
-struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr);
-int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
-				struct dyn_ftrace *rec,
-				unsigned long old_addr,
-				unsigned long new_addr);
 unsigned long ftrace_find_rec_direct(unsigned long ip);
 int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
 int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr,
@@ -415,30 +407,6 @@ int modify_ftrace_direct_multi_nolock(struct ftrace_ops *ops, unsigned long addr
 #else
 struct ftrace_ops;
 # define ftrace_direct_func_count 0
-static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
-{
-	return -ENOTSUPP;
-}
-static inline int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
-{
-	return -ENOTSUPP;
-}
-static inline int modify_ftrace_direct(unsigned long ip,
-				       unsigned long old_addr, unsigned long new_addr)
-{
-	return -ENOTSUPP;
-}
-static inline struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr)
-{
-	return NULL;
-}
-static inline int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
-					      struct dyn_ftrace *rec,
-					      unsigned long old_addr,
-					      unsigned long new_addr)
-{
-	return -ENODEV;
-}
 static inline unsigned long ftrace_find_rec_direct(unsigned long ip)
 {
 	return 0;