Commit 18588e14 authored Nov 18, 2018 by Steven Rostedt (VMware)

s390/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 s390 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.

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Julian Wiedmann <jwi@linux.ibm.com>
Cc: linux-s390@vger.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 e949b6db

arch/s390/kernel/ftrace.c

+2 −11

Original line number	Diff line number	Diff line
		@@ -203,21 +203,12 @@ device_initcall(ftrace_plt_init);
		*/
		unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
		{
		struct ftrace_graph_ent trace;

		if (unlikely(ftrace_graph_is_dead()))
		goto out;
		if (unlikely(atomic_read(&current->tracing_graph_pause)))
		goto out;
		ip -= MCOUNT_INSN_SIZE;
		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 = (unsigned long) return_to_handler;
		out:
		return parent;

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