Commit fe60522e authored Nov 18, 2018 by Steven Rostedt (VMware)

powerpc/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 powerpc 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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: stable@kernel.org
Fixes: 03274a3f ("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>

parent a87532c7

arch/powerpc/kernel/trace/ftrace.c

+2 −13

Original line number	Diff line number	Diff line
		@@ -950,7 +950,6 @@ int ftrace_disable_ftrace_graph_caller(void)
		*/
		unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
		{
		struct ftrace_graph_ent trace;
		unsigned long return_hooker;

		if (unlikely(ftrace_graph_is_dead()))
		@@ -961,17 +960,7 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)

		return_hooker = ppc_function_entry(return_to_handler);

		trace.func = ip;
		trace.depth = current->curr_ret_stack + 1;

		/* Only trace if the calling function expects to */
		if (!ftrace_graph_entry(&trace))
		goto out;

		if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
		NULL) == -EBUSY)
		goto out;

		if (!function_graph_enter(parent, ip, 0, NULL))
		parent = return_hooker;
		out:
		return parent;