riscv/function_graph: Simplify with function_graph_enter()

The function_graph_enter() 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@andestech.com>
Cc: Alan Kao <alankao@andestech.com>
Cc: stable@kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 1157b6b52d259fa79edf0d44f589022174aff18c..c433f6d3dd64f0b4eec0a567854d1cfca59c650f 100644 (file)
--- 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