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https://github.com/torvalds/linux
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ee1d267423
pstore doesn't support unregistering yet. It was marked as TODO. This patch adds some code to fix it: 1) Add functions to unregister kmsg/console/ftrace/pmsg. 2) Add a function to free compression buffer. 3) Unmap the memory and free it. 4) Add a function to unregister pstore filesystem. Signed-off-by: Geliang Tang <geliangtang@163.com> Acked-by: Kees Cook <keescook@chromium.org> [Removed __exit annotation from ramoops_remove(). Reported by Arnd Bergmann] Signed-off-by: Tony Luck <tony.luck@intel.com>
144 lines
3.4 KiB
C
144 lines
3.4 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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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_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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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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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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