mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-19 19:47:03 +07:00
fbccdeb8d7
In preparation for merging the per CPU buffers into one buffer when we retrieve the pstore ftrace data, we store the timestamp as a counter in the ftrace pstore record. We store the CPU number as well if !PSTORE_CPU_IN_IP, in this case we shift the counter and may lose ordering there but we preserve the same record size. The timestamp counter is also racy, and not doing any locking or synchronization here results in the benefit of lower overhead. Since we don't care much here for exact ordering of function traces across CPUs, we don't synchronize and may lose some counter updates but I'm ok with that. Using trace_clock() results in much lower performance so avoid using it since we don't want accuracy in timestamp and need a rough ordering to perform merge. Signed-off-by: Joel Fernandes <joelaf@google.com> [kees: updated commit message, added comments] Signed-off-by: Kees Cook <keescook@chromium.org>
149 lines
3.5 KiB
C
149 lines
3.5 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"
|
|
|
|
/* This doesn't need to be atomic: speed is chosen over correctness here. */
|
|
static u64 pstore_ftrace_stamp;
|
|
|
|
static void notrace pstore_ftrace_call(unsigned long ip,
|
|
unsigned long parent_ip,
|
|
struct ftrace_ops *op,
|
|
struct pt_regs *regs)
|
|
{
|
|
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_write_timestamp(&rec, pstore_ftrace_stamp++);
|
|
pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
|
|
psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
|
|
0, 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,
|
|
};
|
|
|
|
static struct dentry *pstore_ftrace_dir;
|
|
|
|
void pstore_register_ftrace(void)
|
|
{
|
|
struct dentry *file;
|
|
|
|
if (!psinfo->write_buf)
|
|
return;
|
|
|
|
pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
|
|
if (!pstore_ftrace_dir) {
|
|
pr_err("%s: unable to create pstore directory\n", __func__);
|
|
return;
|
|
}
|
|
|
|
file = debugfs_create_file("record_ftrace", 0600, pstore_ftrace_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(pstore_ftrace_dir);
|
|
}
|
|
|
|
void pstore_unregister_ftrace(void)
|
|
{
|
|
mutex_lock(&pstore_ftrace_lock);
|
|
if (pstore_ftrace_enabled) {
|
|
unregister_ftrace_function(&pstore_ftrace_ops);
|
|
pstore_ftrace_enabled = 0;
|
|
}
|
|
mutex_unlock(&pstore_ftrace_lock);
|
|
|
|
debugfs_remove_recursive(pstore_ftrace_dir);
|
|
}
|