linux_kernel/arch/riscv/kernel/ftrace.c

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2013 Linaro Limited
 * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
 * Copyright (C) 2017 Andes Technology Corporation
 */

#include <linux/ftrace.h>

/*
 * Most of this file is copied from arm64.
 */
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
			   unsigned long frame_pointer)
{
	unsigned long return_hooker = (unsigned long)&return_to_handler;
	unsigned long old;
	struct ftrace_graph_ent trace;
	int err;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))
		return;

	/*
	 * We don't suffer access faults, so no extra fault-recovery assembly
	 * is needed here.
	 */
	old = *parent;

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

	if (!ftrace_graph_entry(&trace))
		return;

	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
				       frame_pointer, NULL);
	if (err == -EBUSY)
		return;
	*parent = return_hooker;
}