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
 30/* This doesn't need to be atomic: speed is chosen over correctness here. */
 31static u64 pstore_ftrace_stamp;
 32
 33static void notrace pstore_ftrace_call(unsigned long ip,
 34				       unsigned long parent_ip,
 35				       struct ftrace_ops *op,
 36				       struct pt_regs *regs)
 37{
 38	unsigned long flags;
 39	struct pstore_ftrace_record rec = {};
 40	struct pstore_record record = {
 41		.type = PSTORE_TYPE_FTRACE,
 42		.buf = (char *)&rec,
 43		.size = sizeof(rec),
 44		.psi = psinfo,
 45	};
 46
 47	if (unlikely(oops_in_progress))
 48		return;
 49
 50	local_irq_save(flags);
 51
 52	rec.ip = ip;
 53	rec.parent_ip = parent_ip;
 54	pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
 55	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
 56	psinfo->write(&record);
 57
 58	local_irq_restore(flags);
 59}
 60
 61static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
 62	.func	= pstore_ftrace_call,
 63};
 64
 65static DEFINE_MUTEX(pstore_ftrace_lock);
 66static bool pstore_ftrace_enabled;
 67
 68static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
 69					size_t count, loff_t *ppos)
 70{
 71	u8 on;
 72	ssize_t ret;
 73
 74	ret = kstrtou8_from_user(buf, count, 2, &on);
 75	if (ret)
 76		return ret;
 77
 78	mutex_lock(&pstore_ftrace_lock);
 79
 80	if (!on ^ pstore_ftrace_enabled)
 81		goto out;
 82
 83	if (on) {
 84		ftrace_ops_set_global_filter(&pstore_ftrace_ops);
 85		ret = register_ftrace_function(&pstore_ftrace_ops);
 86	} else {
 87		ret = unregister_ftrace_function(&pstore_ftrace_ops);
 88	}
 89
 90	if (ret) {
 91		pr_err("%s: unable to %sregister ftrace ops: %zd\n",
 92		       __func__, on ? "" : "un", ret);
 93		goto err;
 94	}
 95
 96	pstore_ftrace_enabled = on;
 97out:
 98	ret = count;
 99err:
100	mutex_unlock(&pstore_ftrace_lock);
101
102	return ret;
103}
104
105static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
106				       size_t count, loff_t *ppos)
107{
108	char val[] = { '0' + pstore_ftrace_enabled, '\n' };
109
110	return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
111}
112
113static const struct file_operations pstore_knob_fops = {
114	.open	= simple_open,
115	.read	= pstore_ftrace_knob_read,
116	.write	= pstore_ftrace_knob_write,
117};
118
119static struct dentry *pstore_ftrace_dir;
120
121void pstore_register_ftrace(void)
122{
123	struct dentry *file;
124
125	if (!psinfo->write)
126		return;
127
128	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
129	if (!pstore_ftrace_dir) {
130		pr_err("%s: unable to create pstore directory\n", __func__);
131		return;
132	}
133
134	file = debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir,
135				   NULL, &pstore_knob_fops);
136	if (!file) {
137		pr_err("%s: unable to create record_ftrace file\n", __func__);
138		goto err_file;
139	}
140
141	return;
142err_file:
143	debugfs_remove(pstore_ftrace_dir);
144}
145
146void pstore_unregister_ftrace(void)
147{
148	mutex_lock(&pstore_ftrace_lock);
149	if (pstore_ftrace_enabled) {
150		unregister_ftrace_function(&pstore_ftrace_ops);
151		pstore_ftrace_enabled = 0;
152	}
153	mutex_unlock(&pstore_ftrace_lock);
154
155	debugfs_remove_recursive(pstore_ftrace_dir);
156}