parisc: 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 parisc 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: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
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>

diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index 6fa8535d3cceb55de7ecf1051fcb2c812dcb1f51..e46a4157a8948862697755439496a16e5acb29f4 100644 (file)
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -30,7 +30,6 @@ static void __hot prepare_ftrace_return(unsigned long *parent,
                                        unsigned long self_addr)
 {
        unsigned long old;
-       struct ftrace_graph_ent trace;
        extern int parisc_return_to_handler;
 
        if (unlikely(ftrace_graph_is_dead()))
@@ -41,19 +40,9 @@ static void __hot prepare_ftrace_return(unsigned long *parent,
 
        old = *parent;
 
-       trace.func = self_addr;
-       trace.depth = current->curr_ret_stack + 1;
-
-       /* Only trace if the calling function expects to */
-       if (!ftrace_graph_entry(&trace))
-               return;
-
-        if (ftrace_push_return_trace(old, self_addr, &trace.depth,
-                                    0, NULL) == -EBUSY)
-                return;
-
-       /* activate parisc_return_to_handler() as return point */
-       *parent = (unsigned long) &parisc_return_to_handler;
+       if (!function_graph_enter(old, self_addr, 0, NULL))
+               /* activate parisc_return_to_handler() as return point */
+               *parent = (unsigned long) &parisc_return_to_handler;
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */