sh/function_graph: Simplify with function_graph_enter()

BugLink: https://bugs.launchpad.net/bugs/1836968
commit bc715ee4dbc5db462c59b9cfba92d31b3274fe3a upstream.

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 superh 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: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c
index 96dd9f7da2506d061fa499c5992a8e7eb4a426bf..1b04270e5460e8d77decb68a5c15f329227706ea 100644 (file)
--- a/arch/sh/kernel/ftrace.c
+++ b/arch/sh/kernel/ftrace.c
@@ -321,8 +321,7 @@ int ftrace_disable_ftrace_graph_caller(void)
 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
 {
        unsigned long old;
-       int faulted, err;
-       struct ftrace_graph_ent trace;
+       int faulted;
        unsigned long return_hooker = (unsigned long)&return_to_handler;
 
        if (unlikely(ftrace_graph_is_dead()))
@@ -365,18 +364,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
                return;
        }
 
-       err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL);
-       if (err == -EBUSY) {
+       if (function_graph_enter(old, self_addr, 0, NULL))
                __raw_writel(old, parent);
-               return;
-       }
-
-       trace.func = self_addr;
-
-       /* Only trace if the calling function expects to */
-       if (!ftrace_graph_entry(&trace)) {
-               current->curr_ret_stack--;
-               __raw_writel(old, parent);
-       }
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */