1/*
  2 * Copyright 2012  Google, Inc.
  3 *
  4 * This software is licensed under the terms of the GNU General Public
  5 * License version 2, as published by the Free Software Foundation, and
  6 * may be copied, distributed, and modified under those terms.
  7 *
  8 * This program is distributed in the hope that it will be useful,
  9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11 * GNU General Public License for more details.
 12 */
 13
 14#include <linux/kernel.h>
 15#include <linux/compiler.h>
 16#include <linux/irqflags.h>
 17#include <linux/percpu.h>
 18#include <linux/smp.h>
 19#include <linux/atomic.h>
 20#include <linux/types.h>
 21#include <linux/mutex.h>
 22#include <linux/ftrace.h>
 23#include <linux/fs.h>
 24#include <linux/debugfs.h>
 25#include <linux/err.h>
 26#include <linux/cache.h>
 27#include <asm/barrier.h>
 28#include "internal.h"
 29
 30static void notrace pstore_ftrace_call(unsigned long ip,
 31				       unsigned long parent_ip,
 32				       struct ftrace_ops *op,
 33				       struct pt_regs *regs)
 34{
 35	unsigned long flags;
 36	struct pstore_ftrace_record rec = {};
 37
 38	if (unlikely(oops_in_progress))
 39		return;
 40
 41	local_irq_save(flags);
 42
 43	rec.ip = ip;
 44	rec.parent_ip = parent_ip;
 45	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
 46	psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
 47			  0, sizeof(rec), psinfo);
 48
 49	local_irq_restore(flags);
 50}
 51
 52static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
 53	.func	= pstore_ftrace_call,
 54};
 55
 56static DEFINE_MUTEX(pstore_ftrace_lock);
 57static bool pstore_ftrace_enabled;
 58
 59static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
 60					size_t count, loff_t *ppos)
 61{
 62	u8 on;
 63	ssize_t ret;
 64
 65	ret = kstrtou8_from_user(buf, count, 2, &on);
 66	if (ret)
 67		return ret;
 68
 69	mutex_lock(&pstore_ftrace_lock);
 70
 71	if (!on ^ pstore_ftrace_enabled)
 72		goto out;
 73
 74	if (on)
 75		ret = register_ftrace_function(&pstore_ftrace_ops);
 76	else
 77		ret = unregister_ftrace_function(&pstore_ftrace_ops);
 78	if (ret) {
 79		pr_err("%s: unable to %sregister ftrace ops: %zd\n",
 80		       __func__, on ? "" : "un", ret);
 81		goto err;
 82	}
 83
 84	pstore_ftrace_enabled = on;
 85out:
 86	ret = count;
 87err:
 88	mutex_unlock(&pstore_ftrace_lock);
 89
 90	return ret;
 91}
 92
 93static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
 94				       size_t count, loff_t *ppos)
 95{
 96	char val[] = { '0' + pstore_ftrace_enabled, '\n' };
 97
 98	return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
 99}
100
101static const struct file_operations pstore_knob_fops = {
102	.open	= simple_open,
103	.read	= pstore_ftrace_knob_read,
104	.write	= pstore_ftrace_knob_write,
105};
106
107void pstore_register_ftrace(void)
108{
109	struct dentry *dir;
110	struct dentry *file;
111
112	if (!psinfo->write_buf)
113		return;
114
115	dir = debugfs_create_dir("pstore", NULL);
116	if (!dir) {
117		pr_err("%s: unable to create pstore directory\n", __func__);
118		return;
119	}
120
121	file = debugfs_create_file("record_ftrace", 0600, dir, NULL,
122				   &pstore_knob_fops);
123	if (!file) {
124		pr_err("%s: unable to create record_ftrace file\n", __func__);
125		goto err_file;
126	}
127
128	return;
129err_file:
130	debugfs_remove(dir);
131}