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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright 2014 Google, Inc.4 */5 6#include <linux/cdev.h>7#include <linux/device.h>8#include <linux/fs.h>9#include <linux/uaccess.h>10#include "internal.h"11 12static DEFINE_MUTEX(pmsg_lock);13 14static ssize_t write_pmsg(struct file *file, const char __user *buf,15 size_t count, loff_t *ppos)16{17 struct pstore_record record;18 int ret;19 20 if (!count)21 return 0;22 23 pstore_record_init(&record, psinfo);24 record.type = PSTORE_TYPE_PMSG;25 record.size = count;26 27 /* check outside lock, page in any data. write_user also checks */28 if (!access_ok(buf, count))29 return -EFAULT;30 31 mutex_lock(&pmsg_lock);32 ret = psinfo->write_user(&record, buf);33 mutex_unlock(&pmsg_lock);34 return ret ? ret : count;35}36 37static const struct file_operations pmsg_fops = {38 .owner = THIS_MODULE,39 .llseek = noop_llseek,40 .write = write_pmsg,41};42 43static struct class *pmsg_class;44static int pmsg_major;45#define PMSG_NAME "pmsg"46#undef pr_fmt47#define pr_fmt(fmt) PMSG_NAME ": " fmt48 49static char *pmsg_devnode(const struct device *dev, umode_t *mode)50{51 if (mode)52 *mode = 0220;53 return NULL;54}55 56void pstore_register_pmsg(void)57{58 struct device *pmsg_device;59 60 pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);61 if (pmsg_major < 0) {62 pr_err("register_chrdev failed\n");63 goto err;64 }65 66 pmsg_class = class_create(PMSG_NAME);67 if (IS_ERR(pmsg_class)) {68 pr_err("device class file already in use\n");69 goto err_class;70 }71 pmsg_class->devnode = pmsg_devnode;72 73 pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0),74 NULL, "%s%d", PMSG_NAME, 0);75 if (IS_ERR(pmsg_device)) {76 pr_err("failed to create device\n");77 goto err_device;78 }79 return;80 81err_device:82 class_destroy(pmsg_class);83err_class:84 unregister_chrdev(pmsg_major, PMSG_NAME);85err:86 return;87}88 89void pstore_unregister_pmsg(void)90{91 device_destroy(pmsg_class, MKDEV(pmsg_major, 0));92 class_destroy(pmsg_class);93 unregister_chrdev(pmsg_major, PMSG_NAME);94}95