65f8c95e46
With this patch we no longer reuse function tracer infrastructure, now we register our own tracer back-end via a debugfs knob. It's a bit more code, but that is the only downside. On the bright side we have: - Ability to make persistent_ram module removable (when needed, we can move ftrace_ops struct into a module). Note that persistent_ram is still not removable for other reasons, but with this patch it's just one thing less to worry about; - Pstore part is more isolated from the generic function tracer. We tried it already by registering our own tracer in available_tracers, but that way we're loosing ability to see the traces while we record them to pstore. This solution is somewhere in the middle: we only register "internal ftracer" back-end, but not the "front-end"; - When there is only pstore tracing enabled, the kernel will only write to the pstore buffer, omitting function tracer buffer (which, of course, still can be enabled via 'echo function > current_tracer'). Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
129 lines
2.9 KiB
C
129 lines
2.9 KiB
C
/*
|
|
* Copyright 2012 Google, Inc.
|
|
*
|
|
* This software is licensed under the terms of the GNU General Public
|
|
* License version 2, as published by the Free Software Foundation, and
|
|
* may be copied, distributed, and modified under those terms.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/irqflags.h>
|
|
#include <linux/percpu.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/atomic.h>
|
|
#include <linux/types.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/ftrace.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/debugfs.h>
|
|
#include <linux/err.h>
|
|
#include <linux/cache.h>
|
|
#include <asm/barrier.h>
|
|
#include "internal.h"
|
|
|
|
static void notrace pstore_ftrace_call(unsigned long ip,
|
|
unsigned long parent_ip)
|
|
{
|
|
unsigned long flags;
|
|
struct pstore_ftrace_record rec = {};
|
|
|
|
if (unlikely(oops_in_progress))
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
|
|
rec.ip = ip;
|
|
rec.parent_ip = parent_ip;
|
|
pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
|
|
psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
|
|
sizeof(rec), psinfo);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
|
|
.func = pstore_ftrace_call,
|
|
};
|
|
|
|
static DEFINE_MUTEX(pstore_ftrace_lock);
|
|
static bool pstore_ftrace_enabled;
|
|
|
|
static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
u8 on;
|
|
ssize_t ret;
|
|
|
|
ret = kstrtou8_from_user(buf, count, 2, &on);
|
|
if (ret)
|
|
return ret;
|
|
|
|
mutex_lock(&pstore_ftrace_lock);
|
|
|
|
if (!on ^ pstore_ftrace_enabled)
|
|
goto out;
|
|
|
|
if (on)
|
|
ret = register_ftrace_function(&pstore_ftrace_ops);
|
|
else
|
|
ret = unregister_ftrace_function(&pstore_ftrace_ops);
|
|
if (ret) {
|
|
pr_err("%s: unable to %sregister ftrace ops: %zd\n",
|
|
__func__, on ? "" : "un", ret);
|
|
goto err;
|
|
}
|
|
|
|
pstore_ftrace_enabled = on;
|
|
out:
|
|
ret = count;
|
|
err:
|
|
mutex_unlock(&pstore_ftrace_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
char val[] = { '0' + pstore_ftrace_enabled, '\n' };
|
|
|
|
return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
|
|
}
|
|
|
|
static const struct file_operations pstore_knob_fops = {
|
|
.open = simple_open,
|
|
.read = pstore_ftrace_knob_read,
|
|
.write = pstore_ftrace_knob_write,
|
|
};
|
|
|
|
void pstore_register_ftrace(void)
|
|
{
|
|
struct dentry *dir;
|
|
struct dentry *file;
|
|
|
|
if (!psinfo->write_buf)
|
|
return;
|
|
|
|
dir = debugfs_create_dir("pstore", NULL);
|
|
if (!dir) {
|
|
pr_err("%s: unable to create pstore directory\n", __func__);
|
|
return;
|
|
}
|
|
|
|
file = debugfs_create_file("record_ftrace", 0600, dir, NULL,
|
|
&pstore_knob_fops);
|
|
if (!file) {
|
|
pr_err("%s: unable to create record_ftrace file\n", __func__);
|
|
goto err_file;
|
|
}
|
|
|
|
return;
|
|
err_file:
|
|
debugfs_remove(dir);
|
|
}
|