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 #define PMSG_MAX_BOUNCE_BUFFER_SIZE (2*PAGE_SIZE) 23 24 static ssize_t write_pmsg(struct file *file, const char __user *buf, 25 size_t count, loff_t *ppos) 26 { 27 size_t i, buffer_size; 28 char *buffer; 29 30 if (!count) 31 return 0; 32 33 if (!access_ok(VERIFY_READ, buf, count)) 34 return -EFAULT; 35 36 buffer_size = count; 37 if (buffer_size > PMSG_MAX_BOUNCE_BUFFER_SIZE) 38 buffer_size = PMSG_MAX_BOUNCE_BUFFER_SIZE; 39 buffer = vmalloc(buffer_size); 40 if (!buffer) 41 return -ENOMEM; 42 43 mutex_lock(&pmsg_lock); 44 for (i = 0; i < count; ) { 45 size_t c = min(count - i, buffer_size); 46 u64 id; 47 long ret; 48 49 ret = __copy_from_user(buffer, buf + i, c); 50 if (unlikely(ret != 0)) { 51 mutex_unlock(&pmsg_lock); 52 vfree(buffer); 53 return -EFAULT; 54 } 55 psinfo->write_buf(PSTORE_TYPE_PMSG, 0, &id, 0, buffer, 0, c, 56 psinfo); 57 58 i += c; 59 } 60 61 mutex_unlock(&pmsg_lock); 62 vfree(buffer); 63 return count; 64 } 65 66 static const struct file_operations pmsg_fops = { 67 .owner = THIS_MODULE, 68 .llseek = noop_llseek, 69 .write = write_pmsg, 70 }; 71 72 static struct class *pmsg_class; 73 static int pmsg_major; 74 #define PMSG_NAME "pmsg" 75 #undef pr_fmt 76 #define pr_fmt(fmt) PMSG_NAME ": " fmt 77 78 static char *pmsg_devnode(struct device *dev, umode_t *mode) 79 { 80 if (mode) 81 *mode = 0220; 82 return NULL; 83 } 84 85 void pstore_register_pmsg(void) 86 { 87 struct device *pmsg_device; 88 89 pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops); 90 if (pmsg_major < 0) { 91 pr_err("register_chrdev failed\n"); 92 goto err; 93 } 94 95 pmsg_class = class_create(THIS_MODULE, PMSG_NAME); 96 if (IS_ERR(pmsg_class)) { 97 pr_err("device class file already in use\n"); 98 goto err_class; 99 } 100 pmsg_class->devnode = pmsg_devnode; 101 102 pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0), 103 NULL, "%s%d", PMSG_NAME, 0); 104 if (IS_ERR(pmsg_device)) { 105 pr_err("failed to create device\n"); 106 goto err_device; 107 } 108 return; 109 110 err_device: 111 class_destroy(pmsg_class); 112 err_class: 113 unregister_chrdev(pmsg_major, PMSG_NAME); 114 err: 115 return; 116 } 117 118 void pstore_unregister_pmsg(void) 119 { 120 device_destroy(pmsg_class, MKDEV(pmsg_major, 0)); 121 class_destroy(pmsg_class); 122 unregister_chrdev(pmsg_major, PMSG_NAME); 123 } 124