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![Joel Fernandes](/assets/img/avatar_default.png)
Currently, pstore doesn't have any filters setup for function tracing. This has the associated overhead and may not be useful for users looking for tracing specific set of functions. ftrace's regular function trace filtering is done writing to tracing/set_ftrace_filter however this is not available if not requested. In order to be able to use this feature, the support to request global filtering introduced earlier in the series should be requested before registering the ftrace ops. Here we do the same. Signed-off-by: Joel Fernandes <joelaf@google.com> Signed-off-by: Kees Cook <keescook@chromium.org>
151 lines
3.6 KiB
C
151 lines
3.6 KiB
C
/*
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* Copyright 2012 Google, Inc.
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/compiler.h>
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#include <linux/irqflags.h>
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#include <linux/percpu.h>
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#include <linux/smp.h>
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#include <linux/atomic.h>
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#include <linux/types.h>
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#include <linux/mutex.h>
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#include <linux/ftrace.h>
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#include <linux/fs.h>
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#include <linux/debugfs.h>
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#include <linux/err.h>
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#include <linux/cache.h>
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#include <asm/barrier.h>
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#include "internal.h"
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/* This doesn't need to be atomic: speed is chosen over correctness here. */
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static u64 pstore_ftrace_stamp;
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static void notrace pstore_ftrace_call(unsigned long ip,
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unsigned long parent_ip,
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struct ftrace_ops *op,
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struct pt_regs *regs)
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{
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unsigned long flags;
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struct pstore_ftrace_record rec = {};
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if (unlikely(oops_in_progress))
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return;
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local_irq_save(flags);
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rec.ip = ip;
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rec.parent_ip = parent_ip;
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pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
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pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
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psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
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0, sizeof(rec), psinfo);
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local_irq_restore(flags);
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}
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static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
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.func = pstore_ftrace_call,
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};
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static DEFINE_MUTEX(pstore_ftrace_lock);
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static bool pstore_ftrace_enabled;
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static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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u8 on;
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ssize_t ret;
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ret = kstrtou8_from_user(buf, count, 2, &on);
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if (ret)
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return ret;
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mutex_lock(&pstore_ftrace_lock);
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if (!on ^ pstore_ftrace_enabled)
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goto out;
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if (on) {
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ftrace_ops_set_global_filter(&pstore_ftrace_ops);
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ret = register_ftrace_function(&pstore_ftrace_ops);
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} else {
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ret = unregister_ftrace_function(&pstore_ftrace_ops);
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}
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if (ret) {
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pr_err("%s: unable to %sregister ftrace ops: %zd\n",
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__func__, on ? "" : "un", ret);
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goto err;
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}
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pstore_ftrace_enabled = on;
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out:
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ret = count;
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err:
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mutex_unlock(&pstore_ftrace_lock);
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return ret;
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}
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static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
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size_t count, loff_t *ppos)
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{
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char val[] = { '0' + pstore_ftrace_enabled, '\n' };
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return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
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}
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static const struct file_operations pstore_knob_fops = {
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.open = simple_open,
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.read = pstore_ftrace_knob_read,
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.write = pstore_ftrace_knob_write,
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};
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static struct dentry *pstore_ftrace_dir;
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void pstore_register_ftrace(void)
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{
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struct dentry *file;
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if (!psinfo->write_buf)
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return;
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pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
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if (!pstore_ftrace_dir) {
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pr_err("%s: unable to create pstore directory\n", __func__);
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return;
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}
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file = debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir,
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NULL, &pstore_knob_fops);
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if (!file) {
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pr_err("%s: unable to create record_ftrace file\n", __func__);
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goto err_file;
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}
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return;
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err_file:
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debugfs_remove(pstore_ftrace_dir);
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}
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void pstore_unregister_ftrace(void)
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{
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mutex_lock(&pstore_ftrace_lock);
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if (pstore_ftrace_enabled) {
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unregister_ftrace_function(&pstore_ftrace_ops);
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pstore_ftrace_enabled = 0;
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}
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mutex_unlock(&pstore_ftrace_lock);
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debugfs_remove_recursive(pstore_ftrace_dir);
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}
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