Commit 07f7175b authored Nov 18, 2018 by Steven Rostedt (VMware)

x86/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 x86 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: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.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 8114865f

arch/x86/kernel/ftrace.c

+1 −14

Original line number	Diff line number	Diff line
		@@ -994,7 +994,6 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
		{
		unsigned long old;
		int faulted;
		struct ftrace_graph_ent trace;
		unsigned long return_hooker = (unsigned long)
		&return_to_handler;

		@@ -1046,19 +1045,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
		return;
		}

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

		/* Only trace if the calling function expects to */
		if (!ftrace_graph_entry(&trace)) {
		if (function_graph_enter(old, self_addr, frame_pointer, parent))
		*parent = old;
		return;
		}

		if (ftrace_push_return_trace(old, self_addr, &trace.depth,
		frame_pointer, parent) == -EBUSY) {
		*parent = old;
		return;
		}
		}
		#endif /* CONFIG_FUNCTION_GRAPH_TRACER */