function_graph: Create function_graph_enter() to consolidate architecture code

commit 8114865ff82e200b383e46821c25cb0625b842b5 upstream.

Currently all the architectures do basically the same thing in preparing the
function graph tracer on entry to a function. This code can be pulled into a
generic location and then this will allow the function graph tracer to be
fixed, as well as extended.

Create a new function graph helper function_graph_enter() that will call the
hook function (ftrace_graph_entry) and the shadow stack operation
(ftrace_push_return_trace), and remove the need of the architecture code to
manage the shadow stack.

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

Cc: stable@kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index a397907e8d72..5717e8f81c59 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -779,6 +779,9 @@ extern void return_to_handler(void);
 extern int
 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 			 unsigned long frame_pointer, unsigned long *retp);
+extern int
+function_graph_enter(unsigned long ret, unsigned long func,
+		     unsigned long frame_pointer, unsigned long *retp);
 
 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 				    unsigned long ret, unsigned long *retp);