[for-next][PATCH 10/18] riscv/function_graph: Simplify with function_graph_entry()

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

The function_graph_entry() function does the work of calling the function
graph hook function and the management of the shadow stack, simplifying the
work done in the architecture dependent prepare_ftrace_return().

Have riscv use the new code, and remove the shadow stack management as well as
having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.

Cc: Greentime Hu <greentime@xxxxxxxxxxxxx>
Cc: Alan Kao <alankao@xxxxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 arch/riscv/kernel/ftrace.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 1157b6b52d25..c433f6d3dd64 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -132,7 +132,6 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 {
 	unsigned long return_hooker = (unsigned long)&return_to_handler;
 	unsigned long old;
-	struct ftrace_graph_ent trace;
 	int err;
 
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
@@ -144,17 +143,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 	 */
 	old = *parent;
 
-	trace.func = self_addr;
-	trace.depth = current->curr_ret_stack + 1;
-
-	if (!ftrace_graph_entry(&trace))
-		return;
-
-	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
-				       frame_pointer, parent);
-	if (err == -EBUSY)
-		return;
-	*parent = return_hooker;
+	if (function_graph_enter(old, self_addr, frame_pointer, parent))
+		*parent = return_hooker;
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-- 
2.19.1