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