1 /* 2 * Copyright 2014 Google, Inc. 3 * 4 * This software is licensed under the terms of the GNU General Public 5 * License version 2, as published by the Free Software Foundation, and 6 * may be copied, distributed, and modified under those terms. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 14 #include <linux/cdev.h> 15 #include <linux/device.h> 16 #include <linux/fs.h> 17 #include <linux/uaccess.h> 18 #include <linux/vmalloc.h> 19 #include "internal.h" 20 21 static DEFINE_MUTEX(pmsg_lock); 22 23 static ssize_t write_pmsg(struct file *file, const char __user *buf, 24 size_t count, loff_t *ppos) 25 { 26 u64 id; 27 int ret; 28 29 if (!count) 30 return 0; 31 32 /* check outside lock, page in any data. write_buf_user also checks */ 33 if (!access_ok(VERIFY_READ, buf, count)) 34 return -EFAULT; 35 36 mutex_lock(&pmsg_lock); 37 ret = psinfo->write_buf_user(PSTORE_TYPE_PMSG, 0, &id, 0, buf, 0, count, 38 psinfo); 39 mutex_unlock(&pmsg_lock); 40 return ret ? ret : count; 41 } 42 43 static const struct file_operations pmsg_fops = { 44 .owner = THIS_MODULE, 45 .llseek = noop_llseek, 46 .write = write_pmsg, 47 }; 48 49 static struct class *pmsg_class; 50 static int pmsg_major; 51 #define PMSG_NAME "pmsg" 52 #undef pr_fmt 53 #define pr_fmt(fmt) PMSG_NAME ": " fmt 54 55 static char *pmsg_devnode(struct device *dev, umode_t *mode) 56 { 57 if (mode) 58 *mode = 0220; 59 return NULL; 60 } 61 62 void pstore_register_pmsg(void) 63 { 64 struct device *pmsg_device; 65 66 pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops); 67 if (pmsg_major < 0) { 68 pr_err("register_chrdev failed\n"); 69 goto err; 70 } 71 72 pmsg_class = class_create(THIS_MODULE, PMSG_NAME); 73 if (IS_ERR(pmsg_class)) { 74 pr_err("device class file already in use\n"); 75 goto err_class; 76 } 77 pmsg_class->devnode = pmsg_devnode; 78 79 pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0), 80 NULL, "%s%d", PMSG_NAME, 0); 81 if (IS_ERR(pmsg_device)) { 82 pr_err("failed to create device\n"); 83 goto err_device; 84 } 85 return; 86 87 err_device: 88 class_destroy(pmsg_class); 89 err_class: 90 unregister_chrdev(pmsg_major, PMSG_NAME); 91 err: 92 return; 93 } 94 95 void pstore_unregister_pmsg(void) 96 { 97 device_destroy(pmsg_class, MKDEV(pmsg_major, 0)); 98 class_destroy(pmsg_class); 99 unregister_chrdev(pmsg_major, PMSG_NAME); 100 } 101