1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Implements pstore backend driver that write to block (or non-block) storage 4 * devices, using the pstore/zone API. 5 */ 6 7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 #include <linux/blkdev.h> 12 #include <linux/string.h> 13 #include <linux/of.h> 14 #include <linux/of_address.h> 15 #include <linux/platform_device.h> 16 #include <linux/pstore_blk.h> 17 #include <linux/fs.h> 18 #include <linux/file.h> 19 #include <linux/init_syscalls.h> 20 #include <linux/mount.h> 21 22 static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE; 23 module_param(kmsg_size, long, 0400); 24 MODULE_PARM_DESC(kmsg_size, "kmsg dump record size in kbytes"); 25 26 static int max_reason = CONFIG_PSTORE_BLK_MAX_REASON; 27 module_param(max_reason, int, 0400); 28 MODULE_PARM_DESC(max_reason, 29 "maximum reason for kmsg dump (default 2: Oops and Panic)"); 30 31 #if IS_ENABLED(CONFIG_PSTORE_PMSG) 32 static long pmsg_size = CONFIG_PSTORE_BLK_PMSG_SIZE; 33 #else 34 static long pmsg_size = -1; 35 #endif 36 module_param(pmsg_size, long, 0400); 37 MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes"); 38 39 #if IS_ENABLED(CONFIG_PSTORE_CONSOLE) 40 static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE; 41 #else 42 static long console_size = -1; 43 #endif 44 module_param(console_size, long, 0400); 45 MODULE_PARM_DESC(console_size, "console size in kbytes"); 46 47 #if IS_ENABLED(CONFIG_PSTORE_FTRACE) 48 static long ftrace_size = CONFIG_PSTORE_BLK_FTRACE_SIZE; 49 #else 50 static long ftrace_size = -1; 51 #endif 52 module_param(ftrace_size, long, 0400); 53 MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes"); 54 55 static bool best_effort; 56 module_param(best_effort, bool, 0400); 57 MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require storage driver pstore support, default: off)"); 58 59 /* 60 * blkdev - the block device to use for pstore storage 61 * See Documentation/admin-guide/pstore-blk.rst for details. 62 */ 63 static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV; 64 module_param_string(blkdev, blkdev, 80, 0400); 65 MODULE_PARM_DESC(blkdev, "block device for pstore storage"); 66 67 /* 68 * All globals must only be accessed under the pstore_blk_lock 69 * during the register/unregister functions. 70 */ 71 static DEFINE_MUTEX(pstore_blk_lock); 72 static struct file *psblk_file; 73 static struct pstore_device_info *pstore_device_info; 74 75 #define check_size(name, alignsize) ({ \ 76 long _##name_ = (name); \ 77 _##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \ 78 if (_##name_ & ((alignsize) - 1)) { \ 79 pr_info(#name " must align to %d\n", \ 80 (alignsize)); \ 81 _##name_ = ALIGN(name, (alignsize)); \ 82 } \ 83 _##name_; \ 84 }) 85 86 #define verify_size(name, alignsize, enabled) { \ 87 long _##name_; \ 88 if (enabled) \ 89 _##name_ = check_size(name, alignsize); \ 90 else \ 91 _##name_ = 0; \ 92 /* Synchronize module parameters with resuls. */ \ 93 name = _##name_ / 1024; \ 94 dev->zone.name = _##name_; \ 95 } 96 97 static int __register_pstore_device(struct pstore_device_info *dev) 98 { 99 int ret; 100 101 lockdep_assert_held(&pstore_blk_lock); 102 103 if (!dev) { 104 pr_err("NULL device info\n"); 105 return -EINVAL; 106 } 107 if (!dev->zone.total_size) { 108 pr_err("zero sized device\n"); 109 return -EINVAL; 110 } 111 if (!dev->zone.read) { 112 pr_err("no read handler for device\n"); 113 return -EINVAL; 114 } 115 if (!dev->zone.write) { 116 pr_err("no write handler for device\n"); 117 return -EINVAL; 118 } 119 120 /* someone already registered before */ 121 if (pstore_device_info) 122 return -EBUSY; 123 124 /* zero means not limit on which backends to attempt to store. */ 125 if (!dev->flags) 126 dev->flags = UINT_MAX; 127 128 /* Copy in module parameters. */ 129 verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG); 130 verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG); 131 verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE); 132 verify_size(ftrace_size, 4096, dev->flags & PSTORE_FLAGS_FTRACE); 133 dev->zone.max_reason = max_reason; 134 135 /* Initialize required zone ownership details. */ 136 dev->zone.name = KBUILD_MODNAME; 137 dev->zone.owner = THIS_MODULE; 138 139 ret = register_pstore_zone(&dev->zone); 140 if (ret == 0) 141 pstore_device_info = dev; 142 143 return ret; 144 } 145 /** 146 * register_pstore_device() - register non-block device to pstore/blk 147 * 148 * @dev: non-block device information 149 * 150 * Return: 151 * * 0 - OK 152 * * Others - something error. 153 */ 154 int register_pstore_device(struct pstore_device_info *dev) 155 { 156 int ret; 157 158 mutex_lock(&pstore_blk_lock); 159 ret = __register_pstore_device(dev); 160 mutex_unlock(&pstore_blk_lock); 161 162 return ret; 163 } 164 EXPORT_SYMBOL_GPL(register_pstore_device); 165 166 static void __unregister_pstore_device(struct pstore_device_info *dev) 167 { 168 lockdep_assert_held(&pstore_blk_lock); 169 if (pstore_device_info && pstore_device_info == dev) { 170 unregister_pstore_zone(&dev->zone); 171 pstore_device_info = NULL; 172 } 173 } 174 175 /** 176 * unregister_pstore_device() - unregister non-block device from pstore/blk 177 * 178 * @dev: non-block device information 179 */ 180 void unregister_pstore_device(struct pstore_device_info *dev) 181 { 182 mutex_lock(&pstore_blk_lock); 183 __unregister_pstore_device(dev); 184 mutex_unlock(&pstore_blk_lock); 185 } 186 EXPORT_SYMBOL_GPL(unregister_pstore_device); 187 188 static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos) 189 { 190 return kernel_read(psblk_file, buf, bytes, &pos); 191 } 192 193 static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes, 194 loff_t pos) 195 { 196 /* Console/Ftrace backend may handle buffer until flush dirty zones */ 197 if (in_interrupt() || irqs_disabled()) 198 return -EBUSY; 199 return kernel_write(psblk_file, buf, bytes, &pos); 200 } 201 202 /* 203 * This takes its configuration only from the module parameters now. 204 */ 205 static int __register_pstore_blk(struct pstore_device_info *dev, 206 const char *devpath) 207 { 208 struct inode *inode; 209 int ret = -ENODEV; 210 211 lockdep_assert_held(&pstore_blk_lock); 212 213 psblk_file = filp_open(devpath, O_RDWR | O_DSYNC | O_NOATIME | O_EXCL, 0); 214 if (IS_ERR(psblk_file)) { 215 ret = PTR_ERR(psblk_file); 216 pr_err("failed to open '%s': %d!\n", devpath, ret); 217 goto err; 218 } 219 220 inode = file_inode(psblk_file); 221 if (!S_ISBLK(inode->i_mode)) { 222 pr_err("'%s' is not block device!\n", devpath); 223 goto err_fput; 224 } 225 226 inode = I_BDEV(psblk_file->f_mapping->host)->bd_inode; 227 dev->zone.total_size = i_size_read(inode); 228 229 ret = __register_pstore_device(dev); 230 if (ret) 231 goto err_fput; 232 233 return 0; 234 235 err_fput: 236 fput(psblk_file); 237 err: 238 psblk_file = NULL; 239 240 return ret; 241 } 242 243 /* get information of pstore/blk */ 244 int pstore_blk_get_config(struct pstore_blk_config *info) 245 { 246 strncpy(info->device, blkdev, 80); 247 info->max_reason = max_reason; 248 info->kmsg_size = check_size(kmsg_size, 4096); 249 info->pmsg_size = check_size(pmsg_size, 4096); 250 info->ftrace_size = check_size(ftrace_size, 4096); 251 info->console_size = check_size(console_size, 4096); 252 253 return 0; 254 } 255 EXPORT_SYMBOL_GPL(pstore_blk_get_config); 256 257 258 #ifndef MODULE 259 static const char devname[] = "/dev/pstore-blk"; 260 static __init const char *early_boot_devpath(const char *initial_devname) 261 { 262 /* 263 * During early boot the real root file system hasn't been 264 * mounted yet, and no device nodes are present yet. Use the 265 * same scheme to find the device that we use for mounting 266 * the root file system. 267 */ 268 dev_t dev = name_to_dev_t(initial_devname); 269 270 if (!dev) { 271 pr_err("failed to resolve '%s'!\n", initial_devname); 272 return initial_devname; 273 } 274 275 init_unlink(devname); 276 init_mknod(devname, S_IFBLK | 0600, new_encode_dev(dev)); 277 278 return devname; 279 } 280 #else 281 static inline const char *early_boot_devpath(const char *initial_devname) 282 { 283 return initial_devname; 284 } 285 #endif 286 287 static int __init __best_effort_init(void) 288 { 289 struct pstore_device_info *best_effort_dev; 290 int ret; 291 292 /* No best-effort mode requested. */ 293 if (!best_effort) 294 return 0; 295 296 /* Reject an empty blkdev. */ 297 if (!blkdev[0]) { 298 pr_err("blkdev empty with best_effort=Y\n"); 299 return -EINVAL; 300 } 301 302 best_effort_dev = kzalloc(sizeof(*best_effort_dev), GFP_KERNEL); 303 if (!best_effort_dev) 304 return -ENOMEM; 305 306 best_effort_dev->zone.read = psblk_generic_blk_read; 307 best_effort_dev->zone.write = psblk_generic_blk_write; 308 309 ret = __register_pstore_blk(best_effort_dev, 310 early_boot_devpath(blkdev)); 311 if (ret) 312 kfree(best_effort_dev); 313 else 314 pr_info("attached %s (%zu) (no dedicated panic_write!)\n", 315 blkdev, best_effort_dev->zone.total_size); 316 317 return ret; 318 } 319 320 static void __exit __best_effort_exit(void) 321 { 322 /* 323 * Currently, the only user of psblk_file is best_effort, so 324 * we can assume that pstore_device_info is associated with it. 325 * Once there are "real" blk devices, there will need to be a 326 * dedicated pstore_blk_info, etc. 327 */ 328 if (psblk_file) { 329 struct pstore_device_info *dev = pstore_device_info; 330 331 __unregister_pstore_device(dev); 332 kfree(dev); 333 fput(psblk_file); 334 psblk_file = NULL; 335 } 336 } 337 338 static int __init pstore_blk_init(void) 339 { 340 int ret; 341 342 mutex_lock(&pstore_blk_lock); 343 ret = __best_effort_init(); 344 mutex_unlock(&pstore_blk_lock); 345 346 return ret; 347 } 348 late_initcall(pstore_blk_init); 349 350 static void __exit pstore_blk_exit(void) 351 { 352 mutex_lock(&pstore_blk_lock); 353 __best_effort_exit(); 354 /* If we've been asked to unload, unregister any remaining device. */ 355 __unregister_pstore_device(pstore_device_info); 356 mutex_unlock(&pstore_blk_lock); 357 } 358 module_exit(pstore_blk_exit); 359 360 MODULE_LICENSE("GPL"); 361 MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>"); 362 MODULE_AUTHOR("Kees Cook <keescook@chromium.org>"); 363 MODULE_DESCRIPTION("pstore backend for block devices"); 364