| 1 | /* |
| 2 | * linux/kernel/printk.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 5 | * |
| 6 | * Modified to make sys_syslog() more flexible: added commands to |
| 7 | * return the last 4k of kernel messages, regardless of whether |
| 8 | * they've been read or not. Added option to suppress kernel printk's |
| 9 | * to the console. Added hook for sending the console messages |
| 10 | * elsewhere, in preparation for a serial line console (someday). |
| 11 | * Ted Ts'o, 2/11/93. |
| 12 | * Modified for sysctl support, 1/8/97, Chris Horn. |
| 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
| 14 | * manfred@colorfullife.com |
| 15 | * Rewrote bits to get rid of console_lock |
| 16 | * 01Mar01 Andrew Morton |
| 17 | */ |
| 18 | |
| 19 | #include <linux/kernel.h> |
| 20 | #include <linux/mm.h> |
| 21 | #include <linux/tty.h> |
| 22 | #include <linux/tty_driver.h> |
| 23 | #include <linux/console.h> |
| 24 | #include <linux/init.h> |
| 25 | #include <linux/jiffies.h> |
| 26 | #include <linux/nmi.h> |
| 27 | #include <linux/module.h> |
| 28 | #include <linux/moduleparam.h> |
| 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
| 30 | #include <linux/delay.h> |
| 31 | #include <linux/smp.h> |
| 32 | #include <linux/security.h> |
| 33 | #include <linux/bootmem.h> |
| 34 | #include <linux/memblock.h> |
| 35 | #include <linux/syscalls.h> |
| 36 | #include <linux/kexec.h> |
| 37 | #include <linux/kdb.h> |
| 38 | #include <linux/ratelimit.h> |
| 39 | #include <linux/kmsg_dump.h> |
| 40 | #include <linux/syslog.h> |
| 41 | #include <linux/cpu.h> |
| 42 | #include <linux/notifier.h> |
| 43 | #include <linux/rculist.h> |
| 44 | #include <linux/poll.h> |
| 45 | #include <linux/irq_work.h> |
| 46 | #include <linux/utsname.h> |
| 47 | #include <linux/ctype.h> |
| 48 | #include <linux/uio.h> |
| 49 | |
| 50 | #include <asm/uaccess.h> |
| 51 | |
| 52 | #define CREATE_TRACE_POINTS |
| 53 | #include <trace/events/printk.h> |
| 54 | |
| 55 | #include "console_cmdline.h" |
| 56 | #include "braille.h" |
| 57 | |
| 58 | int console_printk[4] = { |
| 59 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
| 60 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
| 61 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
| 62 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ |
| 63 | }; |
| 64 | |
| 65 | /* |
| 66 | * Low level drivers may need that to know if they can schedule in |
| 67 | * their unblank() callback or not. So let's export it. |
| 68 | */ |
| 69 | int oops_in_progress; |
| 70 | EXPORT_SYMBOL(oops_in_progress); |
| 71 | |
| 72 | /* |
| 73 | * console_sem protects the console_drivers list, and also |
| 74 | * provides serialisation for access to the entire console |
| 75 | * driver system. |
| 76 | */ |
| 77 | static DEFINE_SEMAPHORE(console_sem); |
| 78 | struct console *console_drivers; |
| 79 | EXPORT_SYMBOL_GPL(console_drivers); |
| 80 | |
| 81 | #ifdef CONFIG_LOCKDEP |
| 82 | static struct lockdep_map console_lock_dep_map = { |
| 83 | .name = "console_lock" |
| 84 | }; |
| 85 | #endif |
| 86 | |
| 87 | /* |
| 88 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use |
| 89 | * macros instead of functions so that _RET_IP_ contains useful information. |
| 90 | */ |
| 91 | #define down_console_sem() do { \ |
| 92 | down(&console_sem);\ |
| 93 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ |
| 94 | } while (0) |
| 95 | |
| 96 | static int __down_trylock_console_sem(unsigned long ip) |
| 97 | { |
| 98 | if (down_trylock(&console_sem)) |
| 99 | return 1; |
| 100 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); |
| 101 | return 0; |
| 102 | } |
| 103 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) |
| 104 | |
| 105 | #define up_console_sem() do { \ |
| 106 | mutex_release(&console_lock_dep_map, 1, _RET_IP_);\ |
| 107 | up(&console_sem);\ |
| 108 | } while (0) |
| 109 | |
| 110 | /* |
| 111 | * This is used for debugging the mess that is the VT code by |
| 112 | * keeping track if we have the console semaphore held. It's |
| 113 | * definitely not the perfect debug tool (we don't know if _WE_ |
| 114 | * hold it and are racing, but it helps tracking those weird code |
| 115 | * paths in the console code where we end up in places I want |
| 116 | * locked without the console sempahore held). |
| 117 | */ |
| 118 | static int console_locked, console_suspended; |
| 119 | |
| 120 | /* |
| 121 | * If exclusive_console is non-NULL then only this console is to be printed to. |
| 122 | */ |
| 123 | static struct console *exclusive_console; |
| 124 | |
| 125 | /* |
| 126 | * Array of consoles built from command line options (console=) |
| 127 | */ |
| 128 | |
| 129 | #define MAX_CMDLINECONSOLES 8 |
| 130 | |
| 131 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; |
| 132 | |
| 133 | static int selected_console = -1; |
| 134 | static int preferred_console = -1; |
| 135 | int console_set_on_cmdline; |
| 136 | EXPORT_SYMBOL(console_set_on_cmdline); |
| 137 | |
| 138 | /* Flag: console code may call schedule() */ |
| 139 | static int console_may_schedule; |
| 140 | |
| 141 | /* |
| 142 | * The printk log buffer consists of a chain of concatenated variable |
| 143 | * length records. Every record starts with a record header, containing |
| 144 | * the overall length of the record. |
| 145 | * |
| 146 | * The heads to the first and last entry in the buffer, as well as the |
| 147 | * sequence numbers of these entries are maintained when messages are |
| 148 | * stored. |
| 149 | * |
| 150 | * If the heads indicate available messages, the length in the header |
| 151 | * tells the start next message. A length == 0 for the next message |
| 152 | * indicates a wrap-around to the beginning of the buffer. |
| 153 | * |
| 154 | * Every record carries the monotonic timestamp in microseconds, as well as |
| 155 | * the standard userspace syslog level and syslog facility. The usual |
| 156 | * kernel messages use LOG_KERN; userspace-injected messages always carry |
| 157 | * a matching syslog facility, by default LOG_USER. The origin of every |
| 158 | * message can be reliably determined that way. |
| 159 | * |
| 160 | * The human readable log message directly follows the message header. The |
| 161 | * length of the message text is stored in the header, the stored message |
| 162 | * is not terminated. |
| 163 | * |
| 164 | * Optionally, a message can carry a dictionary of properties (key/value pairs), |
| 165 | * to provide userspace with a machine-readable message context. |
| 166 | * |
| 167 | * Examples for well-defined, commonly used property names are: |
| 168 | * DEVICE=b12:8 device identifier |
| 169 | * b12:8 block dev_t |
| 170 | * c127:3 char dev_t |
| 171 | * n8 netdev ifindex |
| 172 | * +sound:card0 subsystem:devname |
| 173 | * SUBSYSTEM=pci driver-core subsystem name |
| 174 | * |
| 175 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value |
| 176 | * follows directly after a '=' character. Every property is terminated by |
| 177 | * a '\0' character. The last property is not terminated. |
| 178 | * |
| 179 | * Example of a message structure: |
| 180 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec |
| 181 | * 0008 34 00 record is 52 bytes long |
| 182 | * 000a 0b 00 text is 11 bytes long |
| 183 | * 000c 1f 00 dictionary is 23 bytes long |
| 184 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) |
| 185 | * 0010 69 74 27 73 20 61 20 6c "it's a l" |
| 186 | * 69 6e 65 "ine" |
| 187 | * 001b 44 45 56 49 43 "DEVIC" |
| 188 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" |
| 189 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" |
| 190 | * 67 "g" |
| 191 | * 0032 00 00 00 padding to next message header |
| 192 | * |
| 193 | * The 'struct printk_log' buffer header must never be directly exported to |
| 194 | * userspace, it is a kernel-private implementation detail that might |
| 195 | * need to be changed in the future, when the requirements change. |
| 196 | * |
| 197 | * /dev/kmsg exports the structured data in the following line format: |
| 198 | * "level,sequnum,timestamp;<message text>\n" |
| 199 | * |
| 200 | * The optional key/value pairs are attached as continuation lines starting |
| 201 | * with a space character and terminated by a newline. All possible |
| 202 | * non-prinatable characters are escaped in the "\xff" notation. |
| 203 | * |
| 204 | * Users of the export format should ignore possible additional values |
| 205 | * separated by ',', and find the message after the ';' character. |
| 206 | */ |
| 207 | |
| 208 | enum log_flags { |
| 209 | LOG_NOCONS = 1, /* already flushed, do not print to console */ |
| 210 | LOG_NEWLINE = 2, /* text ended with a newline */ |
| 211 | LOG_PREFIX = 4, /* text started with a prefix */ |
| 212 | LOG_CONT = 8, /* text is a fragment of a continuation line */ |
| 213 | }; |
| 214 | |
| 215 | struct printk_log { |
| 216 | u64 ts_nsec; /* timestamp in nanoseconds */ |
| 217 | u16 len; /* length of entire record */ |
| 218 | u16 text_len; /* length of text buffer */ |
| 219 | u16 dict_len; /* length of dictionary buffer */ |
| 220 | u8 facility; /* syslog facility */ |
| 221 | u8 flags:5; /* internal record flags */ |
| 222 | u8 level:3; /* syslog level */ |
| 223 | }; |
| 224 | |
| 225 | /* |
| 226 | * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken |
| 227 | * within the scheduler's rq lock. It must be released before calling |
| 228 | * console_unlock() or anything else that might wake up a process. |
| 229 | */ |
| 230 | static DEFINE_RAW_SPINLOCK(logbuf_lock); |
| 231 | |
| 232 | #ifdef CONFIG_PRINTK |
| 233 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
| 234 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
| 235 | static u64 syslog_seq; |
| 236 | static u32 syslog_idx; |
| 237 | static enum log_flags syslog_prev; |
| 238 | static size_t syslog_partial; |
| 239 | |
| 240 | /* index and sequence number of the first record stored in the buffer */ |
| 241 | static u64 log_first_seq; |
| 242 | static u32 log_first_idx; |
| 243 | |
| 244 | /* index and sequence number of the next record to store in the buffer */ |
| 245 | static u64 log_next_seq; |
| 246 | static u32 log_next_idx; |
| 247 | |
| 248 | /* the next printk record to write to the console */ |
| 249 | static u64 console_seq; |
| 250 | static u32 console_idx; |
| 251 | static enum log_flags console_prev; |
| 252 | |
| 253 | /* the next printk record to read after the last 'clear' command */ |
| 254 | static u64 clear_seq; |
| 255 | static u32 clear_idx; |
| 256 | |
| 257 | #define PREFIX_MAX 32 |
| 258 | #define LOG_LINE_MAX (1024 - PREFIX_MAX) |
| 259 | |
| 260 | /* record buffer */ |
| 261 | #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) |
| 262 | #define LOG_ALIGN 4 |
| 263 | #else |
| 264 | #define LOG_ALIGN __alignof__(struct printk_log) |
| 265 | #endif |
| 266 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
| 267 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
| 268 | static char *log_buf = __log_buf; |
| 269 | static u32 log_buf_len = __LOG_BUF_LEN; |
| 270 | |
| 271 | /* Return log buffer address */ |
| 272 | char *log_buf_addr_get(void) |
| 273 | { |
| 274 | return log_buf; |
| 275 | } |
| 276 | |
| 277 | /* Return log buffer size */ |
| 278 | u32 log_buf_len_get(void) |
| 279 | { |
| 280 | return log_buf_len; |
| 281 | } |
| 282 | |
| 283 | /* human readable text of the record */ |
| 284 | static char *log_text(const struct printk_log *msg) |
| 285 | { |
| 286 | return (char *)msg + sizeof(struct printk_log); |
| 287 | } |
| 288 | |
| 289 | /* optional key/value pair dictionary attached to the record */ |
| 290 | static char *log_dict(const struct printk_log *msg) |
| 291 | { |
| 292 | return (char *)msg + sizeof(struct printk_log) + msg->text_len; |
| 293 | } |
| 294 | |
| 295 | /* get record by index; idx must point to valid msg */ |
| 296 | static struct printk_log *log_from_idx(u32 idx) |
| 297 | { |
| 298 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
| 299 | |
| 300 | /* |
| 301 | * A length == 0 record is the end of buffer marker. Wrap around and |
| 302 | * read the message at the start of the buffer. |
| 303 | */ |
| 304 | if (!msg->len) |
| 305 | return (struct printk_log *)log_buf; |
| 306 | return msg; |
| 307 | } |
| 308 | |
| 309 | /* get next record; idx must point to valid msg */ |
| 310 | static u32 log_next(u32 idx) |
| 311 | { |
| 312 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
| 313 | |
| 314 | /* length == 0 indicates the end of the buffer; wrap */ |
| 315 | /* |
| 316 | * A length == 0 record is the end of buffer marker. Wrap around and |
| 317 | * read the message at the start of the buffer as *this* one, and |
| 318 | * return the one after that. |
| 319 | */ |
| 320 | if (!msg->len) { |
| 321 | msg = (struct printk_log *)log_buf; |
| 322 | return msg->len; |
| 323 | } |
| 324 | return idx + msg->len; |
| 325 | } |
| 326 | |
| 327 | /* |
| 328 | * Check whether there is enough free space for the given message. |
| 329 | * |
| 330 | * The same values of first_idx and next_idx mean that the buffer |
| 331 | * is either empty or full. |
| 332 | * |
| 333 | * If the buffer is empty, we must respect the position of the indexes. |
| 334 | * They cannot be reset to the beginning of the buffer. |
| 335 | */ |
| 336 | static int logbuf_has_space(u32 msg_size, bool empty) |
| 337 | { |
| 338 | u32 free; |
| 339 | |
| 340 | if (log_next_idx > log_first_idx || empty) |
| 341 | free = max(log_buf_len - log_next_idx, log_first_idx); |
| 342 | else |
| 343 | free = log_first_idx - log_next_idx; |
| 344 | |
| 345 | /* |
| 346 | * We need space also for an empty header that signalizes wrapping |
| 347 | * of the buffer. |
| 348 | */ |
| 349 | return free >= msg_size + sizeof(struct printk_log); |
| 350 | } |
| 351 | |
| 352 | static int log_make_free_space(u32 msg_size) |
| 353 | { |
| 354 | while (log_first_seq < log_next_seq) { |
| 355 | if (logbuf_has_space(msg_size, false)) |
| 356 | return 0; |
| 357 | /* drop old messages until we have enough contiguous space */ |
| 358 | log_first_idx = log_next(log_first_idx); |
| 359 | log_first_seq++; |
| 360 | } |
| 361 | |
| 362 | /* sequence numbers are equal, so the log buffer is empty */ |
| 363 | if (logbuf_has_space(msg_size, true)) |
| 364 | return 0; |
| 365 | |
| 366 | return -ENOMEM; |
| 367 | } |
| 368 | |
| 369 | /* compute the message size including the padding bytes */ |
| 370 | static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) |
| 371 | { |
| 372 | u32 size; |
| 373 | |
| 374 | size = sizeof(struct printk_log) + text_len + dict_len; |
| 375 | *pad_len = (-size) & (LOG_ALIGN - 1); |
| 376 | size += *pad_len; |
| 377 | |
| 378 | return size; |
| 379 | } |
| 380 | |
| 381 | /* |
| 382 | * Define how much of the log buffer we could take at maximum. The value |
| 383 | * must be greater than two. Note that only half of the buffer is available |
| 384 | * when the index points to the middle. |
| 385 | */ |
| 386 | #define MAX_LOG_TAKE_PART 4 |
| 387 | static const char trunc_msg[] = "<truncated>"; |
| 388 | |
| 389 | static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, |
| 390 | u16 *dict_len, u32 *pad_len) |
| 391 | { |
| 392 | /* |
| 393 | * The message should not take the whole buffer. Otherwise, it might |
| 394 | * get removed too soon. |
| 395 | */ |
| 396 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; |
| 397 | if (*text_len > max_text_len) |
| 398 | *text_len = max_text_len; |
| 399 | /* enable the warning message */ |
| 400 | *trunc_msg_len = strlen(trunc_msg); |
| 401 | /* disable the "dict" completely */ |
| 402 | *dict_len = 0; |
| 403 | /* compute the size again, count also the warning message */ |
| 404 | return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); |
| 405 | } |
| 406 | |
| 407 | /* insert record into the buffer, discard old ones, update heads */ |
| 408 | static int log_store(int facility, int level, |
| 409 | enum log_flags flags, u64 ts_nsec, |
| 410 | const char *dict, u16 dict_len, |
| 411 | const char *text, u16 text_len) |
| 412 | { |
| 413 | struct printk_log *msg; |
| 414 | u32 size, pad_len; |
| 415 | u16 trunc_msg_len = 0; |
| 416 | |
| 417 | /* number of '\0' padding bytes to next message */ |
| 418 | size = msg_used_size(text_len, dict_len, &pad_len); |
| 419 | |
| 420 | if (log_make_free_space(size)) { |
| 421 | /* truncate the message if it is too long for empty buffer */ |
| 422 | size = truncate_msg(&text_len, &trunc_msg_len, |
| 423 | &dict_len, &pad_len); |
| 424 | /* survive when the log buffer is too small for trunc_msg */ |
| 425 | if (log_make_free_space(size)) |
| 426 | return 0; |
| 427 | } |
| 428 | |
| 429 | if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { |
| 430 | /* |
| 431 | * This message + an additional empty header does not fit |
| 432 | * at the end of the buffer. Add an empty header with len == 0 |
| 433 | * to signify a wrap around. |
| 434 | */ |
| 435 | memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); |
| 436 | log_next_idx = 0; |
| 437 | } |
| 438 | |
| 439 | /* fill message */ |
| 440 | msg = (struct printk_log *)(log_buf + log_next_idx); |
| 441 | memcpy(log_text(msg), text, text_len); |
| 442 | msg->text_len = text_len; |
| 443 | if (trunc_msg_len) { |
| 444 | memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); |
| 445 | msg->text_len += trunc_msg_len; |
| 446 | } |
| 447 | memcpy(log_dict(msg), dict, dict_len); |
| 448 | msg->dict_len = dict_len; |
| 449 | msg->facility = facility; |
| 450 | msg->level = level & 7; |
| 451 | msg->flags = flags & 0x1f; |
| 452 | if (ts_nsec > 0) |
| 453 | msg->ts_nsec = ts_nsec; |
| 454 | else |
| 455 | msg->ts_nsec = local_clock(); |
| 456 | memset(log_dict(msg) + dict_len, 0, pad_len); |
| 457 | msg->len = size; |
| 458 | |
| 459 | /* insert message */ |
| 460 | log_next_idx += msg->len; |
| 461 | log_next_seq++; |
| 462 | |
| 463 | return msg->text_len; |
| 464 | } |
| 465 | |
| 466 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
| 467 | |
| 468 | static int syslog_action_restricted(int type) |
| 469 | { |
| 470 | if (dmesg_restrict) |
| 471 | return 1; |
| 472 | /* |
| 473 | * Unless restricted, we allow "read all" and "get buffer size" |
| 474 | * for everybody. |
| 475 | */ |
| 476 | return type != SYSLOG_ACTION_READ_ALL && |
| 477 | type != SYSLOG_ACTION_SIZE_BUFFER; |
| 478 | } |
| 479 | |
| 480 | int check_syslog_permissions(int type, bool from_file) |
| 481 | { |
| 482 | /* |
| 483 | * If this is from /proc/kmsg and we've already opened it, then we've |
| 484 | * already done the capabilities checks at open time. |
| 485 | */ |
| 486 | if (from_file && type != SYSLOG_ACTION_OPEN) |
| 487 | return 0; |
| 488 | |
| 489 | if (syslog_action_restricted(type)) { |
| 490 | if (capable(CAP_SYSLOG)) |
| 491 | return 0; |
| 492 | /* |
| 493 | * For historical reasons, accept CAP_SYS_ADMIN too, with |
| 494 | * a warning. |
| 495 | */ |
| 496 | if (capable(CAP_SYS_ADMIN)) { |
| 497 | pr_warn_once("%s (%d): Attempt to access syslog with " |
| 498 | "CAP_SYS_ADMIN but no CAP_SYSLOG " |
| 499 | "(deprecated).\n", |
| 500 | current->comm, task_pid_nr(current)); |
| 501 | return 0; |
| 502 | } |
| 503 | return -EPERM; |
| 504 | } |
| 505 | return security_syslog(type); |
| 506 | } |
| 507 | |
| 508 | |
| 509 | /* /dev/kmsg - userspace message inject/listen interface */ |
| 510 | struct devkmsg_user { |
| 511 | u64 seq; |
| 512 | u32 idx; |
| 513 | enum log_flags prev; |
| 514 | struct mutex lock; |
| 515 | char buf[8192]; |
| 516 | }; |
| 517 | |
| 518 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
| 519 | { |
| 520 | char *buf, *line; |
| 521 | int i; |
| 522 | int level = default_message_loglevel; |
| 523 | int facility = 1; /* LOG_USER */ |
| 524 | size_t len = iov_iter_count(from); |
| 525 | ssize_t ret = len; |
| 526 | |
| 527 | if (len > LOG_LINE_MAX) |
| 528 | return -EINVAL; |
| 529 | buf = kmalloc(len+1, GFP_KERNEL); |
| 530 | if (buf == NULL) |
| 531 | return -ENOMEM; |
| 532 | |
| 533 | buf[len] = '\0'; |
| 534 | if (copy_from_iter(buf, len, from) != len) { |
| 535 | kfree(buf); |
| 536 | return -EFAULT; |
| 537 | } |
| 538 | |
| 539 | /* |
| 540 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace |
| 541 | * the decimal value represents 32bit, the lower 3 bit are the log |
| 542 | * level, the rest are the log facility. |
| 543 | * |
| 544 | * If no prefix or no userspace facility is specified, we |
| 545 | * enforce LOG_USER, to be able to reliably distinguish |
| 546 | * kernel-generated messages from userspace-injected ones. |
| 547 | */ |
| 548 | line = buf; |
| 549 | if (line[0] == '<') { |
| 550 | char *endp = NULL; |
| 551 | |
| 552 | i = simple_strtoul(line+1, &endp, 10); |
| 553 | if (endp && endp[0] == '>') { |
| 554 | level = i & 7; |
| 555 | if (i >> 3) |
| 556 | facility = i >> 3; |
| 557 | endp++; |
| 558 | len -= endp - line; |
| 559 | line = endp; |
| 560 | } |
| 561 | } |
| 562 | |
| 563 | printk_emit(facility, level, NULL, 0, "%s", line); |
| 564 | kfree(buf); |
| 565 | return ret; |
| 566 | } |
| 567 | |
| 568 | static ssize_t devkmsg_read(struct file *file, char __user *buf, |
| 569 | size_t count, loff_t *ppos) |
| 570 | { |
| 571 | struct devkmsg_user *user = file->private_data; |
| 572 | struct printk_log *msg; |
| 573 | u64 ts_usec; |
| 574 | size_t i; |
| 575 | char cont = '-'; |
| 576 | size_t len; |
| 577 | ssize_t ret; |
| 578 | |
| 579 | if (!user) |
| 580 | return -EBADF; |
| 581 | |
| 582 | ret = mutex_lock_interruptible(&user->lock); |
| 583 | if (ret) |
| 584 | return ret; |
| 585 | raw_spin_lock_irq(&logbuf_lock); |
| 586 | while (user->seq == log_next_seq) { |
| 587 | if (file->f_flags & O_NONBLOCK) { |
| 588 | ret = -EAGAIN; |
| 589 | raw_spin_unlock_irq(&logbuf_lock); |
| 590 | goto out; |
| 591 | } |
| 592 | |
| 593 | raw_spin_unlock_irq(&logbuf_lock); |
| 594 | ret = wait_event_interruptible(log_wait, |
| 595 | user->seq != log_next_seq); |
| 596 | if (ret) |
| 597 | goto out; |
| 598 | raw_spin_lock_irq(&logbuf_lock); |
| 599 | } |
| 600 | |
| 601 | if (user->seq < log_first_seq) { |
| 602 | /* our last seen message is gone, return error and reset */ |
| 603 | user->idx = log_first_idx; |
| 604 | user->seq = log_first_seq; |
| 605 | ret = -EPIPE; |
| 606 | raw_spin_unlock_irq(&logbuf_lock); |
| 607 | goto out; |
| 608 | } |
| 609 | |
| 610 | msg = log_from_idx(user->idx); |
| 611 | ts_usec = msg->ts_nsec; |
| 612 | do_div(ts_usec, 1000); |
| 613 | |
| 614 | /* |
| 615 | * If we couldn't merge continuation line fragments during the print, |
| 616 | * export the stored flags to allow an optional external merge of the |
| 617 | * records. Merging the records isn't always neccessarily correct, like |
| 618 | * when we hit a race during printing. In most cases though, it produces |
| 619 | * better readable output. 'c' in the record flags mark the first |
| 620 | * fragment of a line, '+' the following. |
| 621 | */ |
| 622 | if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT)) |
| 623 | cont = 'c'; |
| 624 | else if ((msg->flags & LOG_CONT) || |
| 625 | ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))) |
| 626 | cont = '+'; |
| 627 | |
| 628 | len = sprintf(user->buf, "%u,%llu,%llu,%c;", |
| 629 | (msg->facility << 3) | msg->level, |
| 630 | user->seq, ts_usec, cont); |
| 631 | user->prev = msg->flags; |
| 632 | |
| 633 | /* escape non-printable characters */ |
| 634 | for (i = 0; i < msg->text_len; i++) { |
| 635 | unsigned char c = log_text(msg)[i]; |
| 636 | |
| 637 | if (c < ' ' || c >= 127 || c == '\\') |
| 638 | len += sprintf(user->buf + len, "\\x%02x", c); |
| 639 | else |
| 640 | user->buf[len++] = c; |
| 641 | } |
| 642 | user->buf[len++] = '\n'; |
| 643 | |
| 644 | if (msg->dict_len) { |
| 645 | bool line = true; |
| 646 | |
| 647 | for (i = 0; i < msg->dict_len; i++) { |
| 648 | unsigned char c = log_dict(msg)[i]; |
| 649 | |
| 650 | if (line) { |
| 651 | user->buf[len++] = ' '; |
| 652 | line = false; |
| 653 | } |
| 654 | |
| 655 | if (c == '\0') { |
| 656 | user->buf[len++] = '\n'; |
| 657 | line = true; |
| 658 | continue; |
| 659 | } |
| 660 | |
| 661 | if (c < ' ' || c >= 127 || c == '\\') { |
| 662 | len += sprintf(user->buf + len, "\\x%02x", c); |
| 663 | continue; |
| 664 | } |
| 665 | |
| 666 | user->buf[len++] = c; |
| 667 | } |
| 668 | user->buf[len++] = '\n'; |
| 669 | } |
| 670 | |
| 671 | user->idx = log_next(user->idx); |
| 672 | user->seq++; |
| 673 | raw_spin_unlock_irq(&logbuf_lock); |
| 674 | |
| 675 | if (len > count) { |
| 676 | ret = -EINVAL; |
| 677 | goto out; |
| 678 | } |
| 679 | |
| 680 | if (copy_to_user(buf, user->buf, len)) { |
| 681 | ret = -EFAULT; |
| 682 | goto out; |
| 683 | } |
| 684 | ret = len; |
| 685 | out: |
| 686 | mutex_unlock(&user->lock); |
| 687 | return ret; |
| 688 | } |
| 689 | |
| 690 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) |
| 691 | { |
| 692 | struct devkmsg_user *user = file->private_data; |
| 693 | loff_t ret = 0; |
| 694 | |
| 695 | if (!user) |
| 696 | return -EBADF; |
| 697 | if (offset) |
| 698 | return -ESPIPE; |
| 699 | |
| 700 | raw_spin_lock_irq(&logbuf_lock); |
| 701 | switch (whence) { |
| 702 | case SEEK_SET: |
| 703 | /* the first record */ |
| 704 | user->idx = log_first_idx; |
| 705 | user->seq = log_first_seq; |
| 706 | break; |
| 707 | case SEEK_DATA: |
| 708 | /* |
| 709 | * The first record after the last SYSLOG_ACTION_CLEAR, |
| 710 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself |
| 711 | * changes no global state, and does not clear anything. |
| 712 | */ |
| 713 | user->idx = clear_idx; |
| 714 | user->seq = clear_seq; |
| 715 | break; |
| 716 | case SEEK_END: |
| 717 | /* after the last record */ |
| 718 | user->idx = log_next_idx; |
| 719 | user->seq = log_next_seq; |
| 720 | break; |
| 721 | default: |
| 722 | ret = -EINVAL; |
| 723 | } |
| 724 | raw_spin_unlock_irq(&logbuf_lock); |
| 725 | return ret; |
| 726 | } |
| 727 | |
| 728 | static unsigned int devkmsg_poll(struct file *file, poll_table *wait) |
| 729 | { |
| 730 | struct devkmsg_user *user = file->private_data; |
| 731 | int ret = 0; |
| 732 | |
| 733 | if (!user) |
| 734 | return POLLERR|POLLNVAL; |
| 735 | |
| 736 | poll_wait(file, &log_wait, wait); |
| 737 | |
| 738 | raw_spin_lock_irq(&logbuf_lock); |
| 739 | if (user->seq < log_next_seq) { |
| 740 | /* return error when data has vanished underneath us */ |
| 741 | if (user->seq < log_first_seq) |
| 742 | ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI; |
| 743 | else |
| 744 | ret = POLLIN|POLLRDNORM; |
| 745 | } |
| 746 | raw_spin_unlock_irq(&logbuf_lock); |
| 747 | |
| 748 | return ret; |
| 749 | } |
| 750 | |
| 751 | static int devkmsg_open(struct inode *inode, struct file *file) |
| 752 | { |
| 753 | struct devkmsg_user *user; |
| 754 | int err; |
| 755 | |
| 756 | /* write-only does not need any file context */ |
| 757 | if ((file->f_flags & O_ACCMODE) == O_WRONLY) |
| 758 | return 0; |
| 759 | |
| 760 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, |
| 761 | SYSLOG_FROM_READER); |
| 762 | if (err) |
| 763 | return err; |
| 764 | |
| 765 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); |
| 766 | if (!user) |
| 767 | return -ENOMEM; |
| 768 | |
| 769 | mutex_init(&user->lock); |
| 770 | |
| 771 | raw_spin_lock_irq(&logbuf_lock); |
| 772 | user->idx = log_first_idx; |
| 773 | user->seq = log_first_seq; |
| 774 | raw_spin_unlock_irq(&logbuf_lock); |
| 775 | |
| 776 | file->private_data = user; |
| 777 | return 0; |
| 778 | } |
| 779 | |
| 780 | static int devkmsg_release(struct inode *inode, struct file *file) |
| 781 | { |
| 782 | struct devkmsg_user *user = file->private_data; |
| 783 | |
| 784 | if (!user) |
| 785 | return 0; |
| 786 | |
| 787 | mutex_destroy(&user->lock); |
| 788 | kfree(user); |
| 789 | return 0; |
| 790 | } |
| 791 | |
| 792 | const struct file_operations kmsg_fops = { |
| 793 | .open = devkmsg_open, |
| 794 | .read = devkmsg_read, |
| 795 | .write_iter = devkmsg_write, |
| 796 | .llseek = devkmsg_llseek, |
| 797 | .poll = devkmsg_poll, |
| 798 | .release = devkmsg_release, |
| 799 | }; |
| 800 | |
| 801 | #ifdef CONFIG_KEXEC |
| 802 | /* |
| 803 | * This appends the listed symbols to /proc/vmcore |
| 804 | * |
| 805 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
| 806 | * obtain access to symbols that are otherwise very difficult to locate. These |
| 807 | * symbols are specifically used so that utilities can access and extract the |
| 808 | * dmesg log from a vmcore file after a crash. |
| 809 | */ |
| 810 | void log_buf_kexec_setup(void) |
| 811 | { |
| 812 | VMCOREINFO_SYMBOL(log_buf); |
| 813 | VMCOREINFO_SYMBOL(log_buf_len); |
| 814 | VMCOREINFO_SYMBOL(log_first_idx); |
| 815 | VMCOREINFO_SYMBOL(log_next_idx); |
| 816 | /* |
| 817 | * Export struct printk_log size and field offsets. User space tools can |
| 818 | * parse it and detect any changes to structure down the line. |
| 819 | */ |
| 820 | VMCOREINFO_STRUCT_SIZE(printk_log); |
| 821 | VMCOREINFO_OFFSET(printk_log, ts_nsec); |
| 822 | VMCOREINFO_OFFSET(printk_log, len); |
| 823 | VMCOREINFO_OFFSET(printk_log, text_len); |
| 824 | VMCOREINFO_OFFSET(printk_log, dict_len); |
| 825 | } |
| 826 | #endif |
| 827 | |
| 828 | /* requested log_buf_len from kernel cmdline */ |
| 829 | static unsigned long __initdata new_log_buf_len; |
| 830 | |
| 831 | /* we practice scaling the ring buffer by powers of 2 */ |
| 832 | static void __init log_buf_len_update(unsigned size) |
| 833 | { |
| 834 | if (size) |
| 835 | size = roundup_pow_of_two(size); |
| 836 | if (size > log_buf_len) |
| 837 | new_log_buf_len = size; |
| 838 | } |
| 839 | |
| 840 | /* save requested log_buf_len since it's too early to process it */ |
| 841 | static int __init log_buf_len_setup(char *str) |
| 842 | { |
| 843 | unsigned size = memparse(str, &str); |
| 844 | |
| 845 | log_buf_len_update(size); |
| 846 | |
| 847 | return 0; |
| 848 | } |
| 849 | early_param("log_buf_len", log_buf_len_setup); |
| 850 | |
| 851 | #ifdef CONFIG_SMP |
| 852 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) |
| 853 | |
| 854 | static void __init log_buf_add_cpu(void) |
| 855 | { |
| 856 | unsigned int cpu_extra; |
| 857 | |
| 858 | /* |
| 859 | * archs should set up cpu_possible_bits properly with |
| 860 | * set_cpu_possible() after setup_arch() but just in |
| 861 | * case lets ensure this is valid. |
| 862 | */ |
| 863 | if (num_possible_cpus() == 1) |
| 864 | return; |
| 865 | |
| 866 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; |
| 867 | |
| 868 | /* by default this will only continue through for large > 64 CPUs */ |
| 869 | if (cpu_extra <= __LOG_BUF_LEN / 2) |
| 870 | return; |
| 871 | |
| 872 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", |
| 873 | __LOG_CPU_MAX_BUF_LEN); |
| 874 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", |
| 875 | cpu_extra); |
| 876 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); |
| 877 | |
| 878 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); |
| 879 | } |
| 880 | #else /* !CONFIG_SMP */ |
| 881 | static inline void log_buf_add_cpu(void) {} |
| 882 | #endif /* CONFIG_SMP */ |
| 883 | |
| 884 | void __init setup_log_buf(int early) |
| 885 | { |
| 886 | unsigned long flags; |
| 887 | char *new_log_buf; |
| 888 | int free; |
| 889 | |
| 890 | if (log_buf != __log_buf) |
| 891 | return; |
| 892 | |
| 893 | if (!early && !new_log_buf_len) |
| 894 | log_buf_add_cpu(); |
| 895 | |
| 896 | if (!new_log_buf_len) |
| 897 | return; |
| 898 | |
| 899 | if (early) { |
| 900 | new_log_buf = |
| 901 | memblock_virt_alloc(new_log_buf_len, LOG_ALIGN); |
| 902 | } else { |
| 903 | new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, |
| 904 | LOG_ALIGN); |
| 905 | } |
| 906 | |
| 907 | if (unlikely(!new_log_buf)) { |
| 908 | pr_err("log_buf_len: %ld bytes not available\n", |
| 909 | new_log_buf_len); |
| 910 | return; |
| 911 | } |
| 912 | |
| 913 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 914 | log_buf_len = new_log_buf_len; |
| 915 | log_buf = new_log_buf; |
| 916 | new_log_buf_len = 0; |
| 917 | free = __LOG_BUF_LEN - log_next_idx; |
| 918 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); |
| 919 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 920 | |
| 921 | pr_info("log_buf_len: %d bytes\n", log_buf_len); |
| 922 | pr_info("early log buf free: %d(%d%%)\n", |
| 923 | free, (free * 100) / __LOG_BUF_LEN); |
| 924 | } |
| 925 | |
| 926 | static bool __read_mostly ignore_loglevel; |
| 927 | |
| 928 | static int __init ignore_loglevel_setup(char *str) |
| 929 | { |
| 930 | ignore_loglevel = true; |
| 931 | pr_info("debug: ignoring loglevel setting.\n"); |
| 932 | |
| 933 | return 0; |
| 934 | } |
| 935 | |
| 936 | early_param("ignore_loglevel", ignore_loglevel_setup); |
| 937 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
| 938 | MODULE_PARM_DESC(ignore_loglevel, |
| 939 | "ignore loglevel setting (prints all kernel messages to the console)"); |
| 940 | |
| 941 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
| 942 | |
| 943 | static int boot_delay; /* msecs delay after each printk during bootup */ |
| 944 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
| 945 | |
| 946 | static int __init boot_delay_setup(char *str) |
| 947 | { |
| 948 | unsigned long lpj; |
| 949 | |
| 950 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
| 951 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
| 952 | |
| 953 | get_option(&str, &boot_delay); |
| 954 | if (boot_delay > 10 * 1000) |
| 955 | boot_delay = 0; |
| 956 | |
| 957 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
| 958 | "HZ: %d, loops_per_msec: %llu\n", |
| 959 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
| 960 | return 0; |
| 961 | } |
| 962 | early_param("boot_delay", boot_delay_setup); |
| 963 | |
| 964 | static void boot_delay_msec(int level) |
| 965 | { |
| 966 | unsigned long long k; |
| 967 | unsigned long timeout; |
| 968 | |
| 969 | if ((boot_delay == 0 || system_state != SYSTEM_BOOTING) |
| 970 | || (level >= console_loglevel && !ignore_loglevel)) { |
| 971 | return; |
| 972 | } |
| 973 | |
| 974 | k = (unsigned long long)loops_per_msec * boot_delay; |
| 975 | |
| 976 | timeout = jiffies + msecs_to_jiffies(boot_delay); |
| 977 | while (k) { |
| 978 | k--; |
| 979 | cpu_relax(); |
| 980 | /* |
| 981 | * use (volatile) jiffies to prevent |
| 982 | * compiler reduction; loop termination via jiffies |
| 983 | * is secondary and may or may not happen. |
| 984 | */ |
| 985 | if (time_after(jiffies, timeout)) |
| 986 | break; |
| 987 | touch_nmi_watchdog(); |
| 988 | } |
| 989 | } |
| 990 | #else |
| 991 | static inline void boot_delay_msec(int level) |
| 992 | { |
| 993 | } |
| 994 | #endif |
| 995 | |
| 996 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
| 997 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
| 998 | |
| 999 | static size_t print_time(u64 ts, char *buf) |
| 1000 | { |
| 1001 | unsigned long rem_nsec; |
| 1002 | |
| 1003 | if (!printk_time) |
| 1004 | return 0; |
| 1005 | |
| 1006 | rem_nsec = do_div(ts, 1000000000); |
| 1007 | |
| 1008 | if (!buf) |
| 1009 | return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts); |
| 1010 | |
| 1011 | return sprintf(buf, "[%5lu.%06lu] ", |
| 1012 | (unsigned long)ts, rem_nsec / 1000); |
| 1013 | } |
| 1014 | |
| 1015 | static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf) |
| 1016 | { |
| 1017 | size_t len = 0; |
| 1018 | unsigned int prefix = (msg->facility << 3) | msg->level; |
| 1019 | |
| 1020 | if (syslog) { |
| 1021 | if (buf) { |
| 1022 | len += sprintf(buf, "<%u>", prefix); |
| 1023 | } else { |
| 1024 | len += 3; |
| 1025 | if (prefix > 999) |
| 1026 | len += 3; |
| 1027 | else if (prefix > 99) |
| 1028 | len += 2; |
| 1029 | else if (prefix > 9) |
| 1030 | len++; |
| 1031 | } |
| 1032 | } |
| 1033 | |
| 1034 | len += print_time(msg->ts_nsec, buf ? buf + len : NULL); |
| 1035 | return len; |
| 1036 | } |
| 1037 | |
| 1038 | static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, |
| 1039 | bool syslog, char *buf, size_t size) |
| 1040 | { |
| 1041 | const char *text = log_text(msg); |
| 1042 | size_t text_size = msg->text_len; |
| 1043 | bool prefix = true; |
| 1044 | bool newline = true; |
| 1045 | size_t len = 0; |
| 1046 | |
| 1047 | if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)) |
| 1048 | prefix = false; |
| 1049 | |
| 1050 | if (msg->flags & LOG_CONT) { |
| 1051 | if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE)) |
| 1052 | prefix = false; |
| 1053 | |
| 1054 | if (!(msg->flags & LOG_NEWLINE)) |
| 1055 | newline = false; |
| 1056 | } |
| 1057 | |
| 1058 | do { |
| 1059 | const char *next = memchr(text, '\n', text_size); |
| 1060 | size_t text_len; |
| 1061 | |
| 1062 | if (next) { |
| 1063 | text_len = next - text; |
| 1064 | next++; |
| 1065 | text_size -= next - text; |
| 1066 | } else { |
| 1067 | text_len = text_size; |
| 1068 | } |
| 1069 | |
| 1070 | if (buf) { |
| 1071 | if (print_prefix(msg, syslog, NULL) + |
| 1072 | text_len + 1 >= size - len) |
| 1073 | break; |
| 1074 | |
| 1075 | if (prefix) |
| 1076 | len += print_prefix(msg, syslog, buf + len); |
| 1077 | memcpy(buf + len, text, text_len); |
| 1078 | len += text_len; |
| 1079 | if (next || newline) |
| 1080 | buf[len++] = '\n'; |
| 1081 | } else { |
| 1082 | /* SYSLOG_ACTION_* buffer size only calculation */ |
| 1083 | if (prefix) |
| 1084 | len += print_prefix(msg, syslog, NULL); |
| 1085 | len += text_len; |
| 1086 | if (next || newline) |
| 1087 | len++; |
| 1088 | } |
| 1089 | |
| 1090 | prefix = true; |
| 1091 | text = next; |
| 1092 | } while (text); |
| 1093 | |
| 1094 | return len; |
| 1095 | } |
| 1096 | |
| 1097 | static int syslog_print(char __user *buf, int size) |
| 1098 | { |
| 1099 | char *text; |
| 1100 | struct printk_log *msg; |
| 1101 | int len = 0; |
| 1102 | |
| 1103 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
| 1104 | if (!text) |
| 1105 | return -ENOMEM; |
| 1106 | |
| 1107 | while (size > 0) { |
| 1108 | size_t n; |
| 1109 | size_t skip; |
| 1110 | |
| 1111 | raw_spin_lock_irq(&logbuf_lock); |
| 1112 | if (syslog_seq < log_first_seq) { |
| 1113 | /* messages are gone, move to first one */ |
| 1114 | syslog_seq = log_first_seq; |
| 1115 | syslog_idx = log_first_idx; |
| 1116 | syslog_prev = 0; |
| 1117 | syslog_partial = 0; |
| 1118 | } |
| 1119 | if (syslog_seq == log_next_seq) { |
| 1120 | raw_spin_unlock_irq(&logbuf_lock); |
| 1121 | break; |
| 1122 | } |
| 1123 | |
| 1124 | skip = syslog_partial; |
| 1125 | msg = log_from_idx(syslog_idx); |
| 1126 | n = msg_print_text(msg, syslog_prev, true, text, |
| 1127 | LOG_LINE_MAX + PREFIX_MAX); |
| 1128 | if (n - syslog_partial <= size) { |
| 1129 | /* message fits into buffer, move forward */ |
| 1130 | syslog_idx = log_next(syslog_idx); |
| 1131 | syslog_seq++; |
| 1132 | syslog_prev = msg->flags; |
| 1133 | n -= syslog_partial; |
| 1134 | syslog_partial = 0; |
| 1135 | } else if (!len){ |
| 1136 | /* partial read(), remember position */ |
| 1137 | n = size; |
| 1138 | syslog_partial += n; |
| 1139 | } else |
| 1140 | n = 0; |
| 1141 | raw_spin_unlock_irq(&logbuf_lock); |
| 1142 | |
| 1143 | if (!n) |
| 1144 | break; |
| 1145 | |
| 1146 | if (copy_to_user(buf, text + skip, n)) { |
| 1147 | if (!len) |
| 1148 | len = -EFAULT; |
| 1149 | break; |
| 1150 | } |
| 1151 | |
| 1152 | len += n; |
| 1153 | size -= n; |
| 1154 | buf += n; |
| 1155 | } |
| 1156 | |
| 1157 | kfree(text); |
| 1158 | return len; |
| 1159 | } |
| 1160 | |
| 1161 | static int syslog_print_all(char __user *buf, int size, bool clear) |
| 1162 | { |
| 1163 | char *text; |
| 1164 | int len = 0; |
| 1165 | |
| 1166 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
| 1167 | if (!text) |
| 1168 | return -ENOMEM; |
| 1169 | |
| 1170 | raw_spin_lock_irq(&logbuf_lock); |
| 1171 | if (buf) { |
| 1172 | u64 next_seq; |
| 1173 | u64 seq; |
| 1174 | u32 idx; |
| 1175 | enum log_flags prev; |
| 1176 | |
| 1177 | if (clear_seq < log_first_seq) { |
| 1178 | /* messages are gone, move to first available one */ |
| 1179 | clear_seq = log_first_seq; |
| 1180 | clear_idx = log_first_idx; |
| 1181 | } |
| 1182 | |
| 1183 | /* |
| 1184 | * Find first record that fits, including all following records, |
| 1185 | * into the user-provided buffer for this dump. |
| 1186 | */ |
| 1187 | seq = clear_seq; |
| 1188 | idx = clear_idx; |
| 1189 | prev = 0; |
| 1190 | while (seq < log_next_seq) { |
| 1191 | struct printk_log *msg = log_from_idx(idx); |
| 1192 | |
| 1193 | len += msg_print_text(msg, prev, true, NULL, 0); |
| 1194 | prev = msg->flags; |
| 1195 | idx = log_next(idx); |
| 1196 | seq++; |
| 1197 | } |
| 1198 | |
| 1199 | /* move first record forward until length fits into the buffer */ |
| 1200 | seq = clear_seq; |
| 1201 | idx = clear_idx; |
| 1202 | prev = 0; |
| 1203 | while (len > size && seq < log_next_seq) { |
| 1204 | struct printk_log *msg = log_from_idx(idx); |
| 1205 | |
| 1206 | len -= msg_print_text(msg, prev, true, NULL, 0); |
| 1207 | prev = msg->flags; |
| 1208 | idx = log_next(idx); |
| 1209 | seq++; |
| 1210 | } |
| 1211 | |
| 1212 | /* last message fitting into this dump */ |
| 1213 | next_seq = log_next_seq; |
| 1214 | |
| 1215 | len = 0; |
| 1216 | while (len >= 0 && seq < next_seq) { |
| 1217 | struct printk_log *msg = log_from_idx(idx); |
| 1218 | int textlen; |
| 1219 | |
| 1220 | textlen = msg_print_text(msg, prev, true, text, |
| 1221 | LOG_LINE_MAX + PREFIX_MAX); |
| 1222 | if (textlen < 0) { |
| 1223 | len = textlen; |
| 1224 | break; |
| 1225 | } |
| 1226 | idx = log_next(idx); |
| 1227 | seq++; |
| 1228 | prev = msg->flags; |
| 1229 | |
| 1230 | raw_spin_unlock_irq(&logbuf_lock); |
| 1231 | if (copy_to_user(buf + len, text, textlen)) |
| 1232 | len = -EFAULT; |
| 1233 | else |
| 1234 | len += textlen; |
| 1235 | raw_spin_lock_irq(&logbuf_lock); |
| 1236 | |
| 1237 | if (seq < log_first_seq) { |
| 1238 | /* messages are gone, move to next one */ |
| 1239 | seq = log_first_seq; |
| 1240 | idx = log_first_idx; |
| 1241 | prev = 0; |
| 1242 | } |
| 1243 | } |
| 1244 | } |
| 1245 | |
| 1246 | if (clear) { |
| 1247 | clear_seq = log_next_seq; |
| 1248 | clear_idx = log_next_idx; |
| 1249 | } |
| 1250 | raw_spin_unlock_irq(&logbuf_lock); |
| 1251 | |
| 1252 | kfree(text); |
| 1253 | return len; |
| 1254 | } |
| 1255 | |
| 1256 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
| 1257 | { |
| 1258 | bool clear = false; |
| 1259 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
| 1260 | int error; |
| 1261 | |
| 1262 | error = check_syslog_permissions(type, from_file); |
| 1263 | if (error) |
| 1264 | goto out; |
| 1265 | |
| 1266 | error = security_syslog(type); |
| 1267 | if (error) |
| 1268 | return error; |
| 1269 | |
| 1270 | switch (type) { |
| 1271 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
| 1272 | break; |
| 1273 | case SYSLOG_ACTION_OPEN: /* Open log */ |
| 1274 | break; |
| 1275 | case SYSLOG_ACTION_READ: /* Read from log */ |
| 1276 | error = -EINVAL; |
| 1277 | if (!buf || len < 0) |
| 1278 | goto out; |
| 1279 | error = 0; |
| 1280 | if (!len) |
| 1281 | goto out; |
| 1282 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
| 1283 | error = -EFAULT; |
| 1284 | goto out; |
| 1285 | } |
| 1286 | error = wait_event_interruptible(log_wait, |
| 1287 | syslog_seq != log_next_seq); |
| 1288 | if (error) |
| 1289 | goto out; |
| 1290 | error = syslog_print(buf, len); |
| 1291 | break; |
| 1292 | /* Read/clear last kernel messages */ |
| 1293 | case SYSLOG_ACTION_READ_CLEAR: |
| 1294 | clear = true; |
| 1295 | /* FALL THRU */ |
| 1296 | /* Read last kernel messages */ |
| 1297 | case SYSLOG_ACTION_READ_ALL: |
| 1298 | error = -EINVAL; |
| 1299 | if (!buf || len < 0) |
| 1300 | goto out; |
| 1301 | error = 0; |
| 1302 | if (!len) |
| 1303 | goto out; |
| 1304 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
| 1305 | error = -EFAULT; |
| 1306 | goto out; |
| 1307 | } |
| 1308 | error = syslog_print_all(buf, len, clear); |
| 1309 | break; |
| 1310 | /* Clear ring buffer */ |
| 1311 | case SYSLOG_ACTION_CLEAR: |
| 1312 | syslog_print_all(NULL, 0, true); |
| 1313 | break; |
| 1314 | /* Disable logging to console */ |
| 1315 | case SYSLOG_ACTION_CONSOLE_OFF: |
| 1316 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
| 1317 | saved_console_loglevel = console_loglevel; |
| 1318 | console_loglevel = minimum_console_loglevel; |
| 1319 | break; |
| 1320 | /* Enable logging to console */ |
| 1321 | case SYSLOG_ACTION_CONSOLE_ON: |
| 1322 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
| 1323 | console_loglevel = saved_console_loglevel; |
| 1324 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
| 1325 | } |
| 1326 | break; |
| 1327 | /* Set level of messages printed to console */ |
| 1328 | case SYSLOG_ACTION_CONSOLE_LEVEL: |
| 1329 | error = -EINVAL; |
| 1330 | if (len < 1 || len > 8) |
| 1331 | goto out; |
| 1332 | if (len < minimum_console_loglevel) |
| 1333 | len = minimum_console_loglevel; |
| 1334 | console_loglevel = len; |
| 1335 | /* Implicitly re-enable logging to console */ |
| 1336 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
| 1337 | error = 0; |
| 1338 | break; |
| 1339 | /* Number of chars in the log buffer */ |
| 1340 | case SYSLOG_ACTION_SIZE_UNREAD: |
| 1341 | raw_spin_lock_irq(&logbuf_lock); |
| 1342 | if (syslog_seq < log_first_seq) { |
| 1343 | /* messages are gone, move to first one */ |
| 1344 | syslog_seq = log_first_seq; |
| 1345 | syslog_idx = log_first_idx; |
| 1346 | syslog_prev = 0; |
| 1347 | syslog_partial = 0; |
| 1348 | } |
| 1349 | if (from_file) { |
| 1350 | /* |
| 1351 | * Short-cut for poll(/"proc/kmsg") which simply checks |
| 1352 | * for pending data, not the size; return the count of |
| 1353 | * records, not the length. |
| 1354 | */ |
| 1355 | error = log_next_seq - syslog_seq; |
| 1356 | } else { |
| 1357 | u64 seq = syslog_seq; |
| 1358 | u32 idx = syslog_idx; |
| 1359 | enum log_flags prev = syslog_prev; |
| 1360 | |
| 1361 | error = 0; |
| 1362 | while (seq < log_next_seq) { |
| 1363 | struct printk_log *msg = log_from_idx(idx); |
| 1364 | |
| 1365 | error += msg_print_text(msg, prev, true, NULL, 0); |
| 1366 | idx = log_next(idx); |
| 1367 | seq++; |
| 1368 | prev = msg->flags; |
| 1369 | } |
| 1370 | error -= syslog_partial; |
| 1371 | } |
| 1372 | raw_spin_unlock_irq(&logbuf_lock); |
| 1373 | break; |
| 1374 | /* Size of the log buffer */ |
| 1375 | case SYSLOG_ACTION_SIZE_BUFFER: |
| 1376 | error = log_buf_len; |
| 1377 | break; |
| 1378 | default: |
| 1379 | error = -EINVAL; |
| 1380 | break; |
| 1381 | } |
| 1382 | out: |
| 1383 | return error; |
| 1384 | } |
| 1385 | |
| 1386 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
| 1387 | { |
| 1388 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
| 1389 | } |
| 1390 | |
| 1391 | /* |
| 1392 | * Call the console drivers, asking them to write out |
| 1393 | * log_buf[start] to log_buf[end - 1]. |
| 1394 | * The console_lock must be held. |
| 1395 | */ |
| 1396 | static void call_console_drivers(int level, const char *text, size_t len) |
| 1397 | { |
| 1398 | struct console *con; |
| 1399 | |
| 1400 | trace_console(text, len); |
| 1401 | |
| 1402 | if (level >= console_loglevel && !ignore_loglevel) |
| 1403 | return; |
| 1404 | if (!console_drivers) |
| 1405 | return; |
| 1406 | |
| 1407 | for_each_console(con) { |
| 1408 | if (exclusive_console && con != exclusive_console) |
| 1409 | continue; |
| 1410 | if (!(con->flags & CON_ENABLED)) |
| 1411 | continue; |
| 1412 | if (!con->write) |
| 1413 | continue; |
| 1414 | if (!cpu_online(smp_processor_id()) && |
| 1415 | !(con->flags & CON_ANYTIME)) |
| 1416 | continue; |
| 1417 | con->write(con, text, len); |
| 1418 | } |
| 1419 | } |
| 1420 | |
| 1421 | /* |
| 1422 | * Zap console related locks when oopsing. |
| 1423 | * To leave time for slow consoles to print a full oops, |
| 1424 | * only zap at most once every 30 seconds. |
| 1425 | */ |
| 1426 | static void zap_locks(void) |
| 1427 | { |
| 1428 | static unsigned long oops_timestamp; |
| 1429 | |
| 1430 | if (time_after_eq(jiffies, oops_timestamp) && |
| 1431 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
| 1432 | return; |
| 1433 | |
| 1434 | oops_timestamp = jiffies; |
| 1435 | |
| 1436 | debug_locks_off(); |
| 1437 | /* If a crash is occurring, make sure we can't deadlock */ |
| 1438 | raw_spin_lock_init(&logbuf_lock); |
| 1439 | /* And make sure that we print immediately */ |
| 1440 | sema_init(&console_sem, 1); |
| 1441 | } |
| 1442 | |
| 1443 | /* |
| 1444 | * Check if we have any console that is capable of printing while cpu is |
| 1445 | * booting or shutting down. Requires console_sem. |
| 1446 | */ |
| 1447 | static int have_callable_console(void) |
| 1448 | { |
| 1449 | struct console *con; |
| 1450 | |
| 1451 | for_each_console(con) |
| 1452 | if (con->flags & CON_ANYTIME) |
| 1453 | return 1; |
| 1454 | |
| 1455 | return 0; |
| 1456 | } |
| 1457 | |
| 1458 | /* |
| 1459 | * Can we actually use the console at this time on this cpu? |
| 1460 | * |
| 1461 | * Console drivers may assume that per-cpu resources have been allocated. So |
| 1462 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't |
| 1463 | * call them until this CPU is officially up. |
| 1464 | */ |
| 1465 | static inline int can_use_console(unsigned int cpu) |
| 1466 | { |
| 1467 | return cpu_online(cpu) || have_callable_console(); |
| 1468 | } |
| 1469 | |
| 1470 | /* |
| 1471 | * Try to get console ownership to actually show the kernel |
| 1472 | * messages from a 'printk'. Return true (and with the |
| 1473 | * console_lock held, and 'console_locked' set) if it |
| 1474 | * is successful, false otherwise. |
| 1475 | */ |
| 1476 | static int console_trylock_for_printk(void) |
| 1477 | { |
| 1478 | unsigned int cpu = smp_processor_id(); |
| 1479 | |
| 1480 | if (!console_trylock()) |
| 1481 | return 0; |
| 1482 | /* |
| 1483 | * If we can't use the console, we need to release the console |
| 1484 | * semaphore by hand to avoid flushing the buffer. We need to hold the |
| 1485 | * console semaphore in order to do this test safely. |
| 1486 | */ |
| 1487 | if (!can_use_console(cpu)) { |
| 1488 | console_locked = 0; |
| 1489 | up_console_sem(); |
| 1490 | return 0; |
| 1491 | } |
| 1492 | return 1; |
| 1493 | } |
| 1494 | |
| 1495 | int printk_delay_msec __read_mostly; |
| 1496 | |
| 1497 | static inline void printk_delay(void) |
| 1498 | { |
| 1499 | if (unlikely(printk_delay_msec)) { |
| 1500 | int m = printk_delay_msec; |
| 1501 | |
| 1502 | while (m--) { |
| 1503 | mdelay(1); |
| 1504 | touch_nmi_watchdog(); |
| 1505 | } |
| 1506 | } |
| 1507 | } |
| 1508 | |
| 1509 | /* |
| 1510 | * Continuation lines are buffered, and not committed to the record buffer |
| 1511 | * until the line is complete, or a race forces it. The line fragments |
| 1512 | * though, are printed immediately to the consoles to ensure everything has |
| 1513 | * reached the console in case of a kernel crash. |
| 1514 | */ |
| 1515 | static struct cont { |
| 1516 | char buf[LOG_LINE_MAX]; |
| 1517 | size_t len; /* length == 0 means unused buffer */ |
| 1518 | size_t cons; /* bytes written to console */ |
| 1519 | struct task_struct *owner; /* task of first print*/ |
| 1520 | u64 ts_nsec; /* time of first print */ |
| 1521 | u8 level; /* log level of first message */ |
| 1522 | u8 facility; /* log facility of first message */ |
| 1523 | enum log_flags flags; /* prefix, newline flags */ |
| 1524 | bool flushed:1; /* buffer sealed and committed */ |
| 1525 | } cont; |
| 1526 | |
| 1527 | static void cont_flush(enum log_flags flags) |
| 1528 | { |
| 1529 | if (cont.flushed) |
| 1530 | return; |
| 1531 | if (cont.len == 0) |
| 1532 | return; |
| 1533 | |
| 1534 | if (cont.cons) { |
| 1535 | /* |
| 1536 | * If a fragment of this line was directly flushed to the |
| 1537 | * console; wait for the console to pick up the rest of the |
| 1538 | * line. LOG_NOCONS suppresses a duplicated output. |
| 1539 | */ |
| 1540 | log_store(cont.facility, cont.level, flags | LOG_NOCONS, |
| 1541 | cont.ts_nsec, NULL, 0, cont.buf, cont.len); |
| 1542 | cont.flags = flags; |
| 1543 | cont.flushed = true; |
| 1544 | } else { |
| 1545 | /* |
| 1546 | * If no fragment of this line ever reached the console, |
| 1547 | * just submit it to the store and free the buffer. |
| 1548 | */ |
| 1549 | log_store(cont.facility, cont.level, flags, 0, |
| 1550 | NULL, 0, cont.buf, cont.len); |
| 1551 | cont.len = 0; |
| 1552 | } |
| 1553 | } |
| 1554 | |
| 1555 | static bool cont_add(int facility, int level, const char *text, size_t len) |
| 1556 | { |
| 1557 | if (cont.len && cont.flushed) |
| 1558 | return false; |
| 1559 | |
| 1560 | if (cont.len + len > sizeof(cont.buf)) { |
| 1561 | /* the line gets too long, split it up in separate records */ |
| 1562 | cont_flush(LOG_CONT); |
| 1563 | return false; |
| 1564 | } |
| 1565 | |
| 1566 | if (!cont.len) { |
| 1567 | cont.facility = facility; |
| 1568 | cont.level = level; |
| 1569 | cont.owner = current; |
| 1570 | cont.ts_nsec = local_clock(); |
| 1571 | cont.flags = 0; |
| 1572 | cont.cons = 0; |
| 1573 | cont.flushed = false; |
| 1574 | } |
| 1575 | |
| 1576 | memcpy(cont.buf + cont.len, text, len); |
| 1577 | cont.len += len; |
| 1578 | |
| 1579 | if (cont.len > (sizeof(cont.buf) * 80) / 100) |
| 1580 | cont_flush(LOG_CONT); |
| 1581 | |
| 1582 | return true; |
| 1583 | } |
| 1584 | |
| 1585 | static size_t cont_print_text(char *text, size_t size) |
| 1586 | { |
| 1587 | size_t textlen = 0; |
| 1588 | size_t len; |
| 1589 | |
| 1590 | if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) { |
| 1591 | textlen += print_time(cont.ts_nsec, text); |
| 1592 | size -= textlen; |
| 1593 | } |
| 1594 | |
| 1595 | len = cont.len - cont.cons; |
| 1596 | if (len > 0) { |
| 1597 | if (len+1 > size) |
| 1598 | len = size-1; |
| 1599 | memcpy(text + textlen, cont.buf + cont.cons, len); |
| 1600 | textlen += len; |
| 1601 | cont.cons = cont.len; |
| 1602 | } |
| 1603 | |
| 1604 | if (cont.flushed) { |
| 1605 | if (cont.flags & LOG_NEWLINE) |
| 1606 | text[textlen++] = '\n'; |
| 1607 | /* got everything, release buffer */ |
| 1608 | cont.len = 0; |
| 1609 | } |
| 1610 | return textlen; |
| 1611 | } |
| 1612 | |
| 1613 | asmlinkage int vprintk_emit(int facility, int level, |
| 1614 | const char *dict, size_t dictlen, |
| 1615 | const char *fmt, va_list args) |
| 1616 | { |
| 1617 | static int recursion_bug; |
| 1618 | static char textbuf[LOG_LINE_MAX]; |
| 1619 | char *text = textbuf; |
| 1620 | size_t text_len = 0; |
| 1621 | enum log_flags lflags = 0; |
| 1622 | unsigned long flags; |
| 1623 | int this_cpu; |
| 1624 | int printed_len = 0; |
| 1625 | bool in_sched = false; |
| 1626 | /* cpu currently holding logbuf_lock in this function */ |
| 1627 | static unsigned int logbuf_cpu = UINT_MAX; |
| 1628 | |
| 1629 | if (level == LOGLEVEL_SCHED) { |
| 1630 | level = LOGLEVEL_DEFAULT; |
| 1631 | in_sched = true; |
| 1632 | } |
| 1633 | |
| 1634 | boot_delay_msec(level); |
| 1635 | printk_delay(); |
| 1636 | |
| 1637 | /* This stops the holder of console_sem just where we want him */ |
| 1638 | local_irq_save(flags); |
| 1639 | this_cpu = smp_processor_id(); |
| 1640 | |
| 1641 | /* |
| 1642 | * Ouch, printk recursed into itself! |
| 1643 | */ |
| 1644 | if (unlikely(logbuf_cpu == this_cpu)) { |
| 1645 | /* |
| 1646 | * If a crash is occurring during printk() on this CPU, |
| 1647 | * then try to get the crash message out but make sure |
| 1648 | * we can't deadlock. Otherwise just return to avoid the |
| 1649 | * recursion and return - but flag the recursion so that |
| 1650 | * it can be printed at the next appropriate moment: |
| 1651 | */ |
| 1652 | if (!oops_in_progress && !lockdep_recursing(current)) { |
| 1653 | recursion_bug = 1; |
| 1654 | local_irq_restore(flags); |
| 1655 | return 0; |
| 1656 | } |
| 1657 | zap_locks(); |
| 1658 | } |
| 1659 | |
| 1660 | lockdep_off(); |
| 1661 | raw_spin_lock(&logbuf_lock); |
| 1662 | logbuf_cpu = this_cpu; |
| 1663 | |
| 1664 | if (unlikely(recursion_bug)) { |
| 1665 | static const char recursion_msg[] = |
| 1666 | "BUG: recent printk recursion!"; |
| 1667 | |
| 1668 | recursion_bug = 0; |
| 1669 | /* emit KERN_CRIT message */ |
| 1670 | printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0, |
| 1671 | NULL, 0, recursion_msg, |
| 1672 | strlen(recursion_msg)); |
| 1673 | } |
| 1674 | |
| 1675 | /* |
| 1676 | * The printf needs to come first; we need the syslog |
| 1677 | * prefix which might be passed-in as a parameter. |
| 1678 | */ |
| 1679 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
| 1680 | |
| 1681 | /* mark and strip a trailing newline */ |
| 1682 | if (text_len && text[text_len-1] == '\n') { |
| 1683 | text_len--; |
| 1684 | lflags |= LOG_NEWLINE; |
| 1685 | } |
| 1686 | |
| 1687 | /* strip kernel syslog prefix and extract log level or control flags */ |
| 1688 | if (facility == 0) { |
| 1689 | int kern_level = printk_get_level(text); |
| 1690 | |
| 1691 | if (kern_level) { |
| 1692 | const char *end_of_header = printk_skip_level(text); |
| 1693 | switch (kern_level) { |
| 1694 | case '0' ... '7': |
| 1695 | if (level == LOGLEVEL_DEFAULT) |
| 1696 | level = kern_level - '0'; |
| 1697 | /* fallthrough */ |
| 1698 | case 'd': /* KERN_DEFAULT */ |
| 1699 | lflags |= LOG_PREFIX; |
| 1700 | } |
| 1701 | /* |
| 1702 | * No need to check length here because vscnprintf |
| 1703 | * put '\0' at the end of the string. Only valid and |
| 1704 | * newly printed level is detected. |
| 1705 | */ |
| 1706 | text_len -= end_of_header - text; |
| 1707 | text = (char *)end_of_header; |
| 1708 | } |
| 1709 | } |
| 1710 | |
| 1711 | if (level == LOGLEVEL_DEFAULT) |
| 1712 | level = default_message_loglevel; |
| 1713 | |
| 1714 | if (dict) |
| 1715 | lflags |= LOG_PREFIX|LOG_NEWLINE; |
| 1716 | |
| 1717 | if (!(lflags & LOG_NEWLINE)) { |
| 1718 | /* |
| 1719 | * Flush the conflicting buffer. An earlier newline was missing, |
| 1720 | * or another task also prints continuation lines. |
| 1721 | */ |
| 1722 | if (cont.len && (lflags & LOG_PREFIX || cont.owner != current)) |
| 1723 | cont_flush(LOG_NEWLINE); |
| 1724 | |
| 1725 | /* buffer line if possible, otherwise store it right away */ |
| 1726 | if (cont_add(facility, level, text, text_len)) |
| 1727 | printed_len += text_len; |
| 1728 | else |
| 1729 | printed_len += log_store(facility, level, |
| 1730 | lflags | LOG_CONT, 0, |
| 1731 | dict, dictlen, text, text_len); |
| 1732 | } else { |
| 1733 | bool stored = false; |
| 1734 | |
| 1735 | /* |
| 1736 | * If an earlier newline was missing and it was the same task, |
| 1737 | * either merge it with the current buffer and flush, or if |
| 1738 | * there was a race with interrupts (prefix == true) then just |
| 1739 | * flush it out and store this line separately. |
| 1740 | * If the preceding printk was from a different task and missed |
| 1741 | * a newline, flush and append the newline. |
| 1742 | */ |
| 1743 | if (cont.len) { |
| 1744 | if (cont.owner == current && !(lflags & LOG_PREFIX)) |
| 1745 | stored = cont_add(facility, level, text, |
| 1746 | text_len); |
| 1747 | cont_flush(LOG_NEWLINE); |
| 1748 | } |
| 1749 | |
| 1750 | if (stored) |
| 1751 | printed_len += text_len; |
| 1752 | else |
| 1753 | printed_len += log_store(facility, level, lflags, 0, |
| 1754 | dict, dictlen, text, text_len); |
| 1755 | } |
| 1756 | |
| 1757 | logbuf_cpu = UINT_MAX; |
| 1758 | raw_spin_unlock(&logbuf_lock); |
| 1759 | lockdep_on(); |
| 1760 | local_irq_restore(flags); |
| 1761 | |
| 1762 | /* If called from the scheduler, we can not call up(). */ |
| 1763 | if (!in_sched) { |
| 1764 | lockdep_off(); |
| 1765 | /* |
| 1766 | * Disable preemption to avoid being preempted while holding |
| 1767 | * console_sem which would prevent anyone from printing to |
| 1768 | * console |
| 1769 | */ |
| 1770 | preempt_disable(); |
| 1771 | |
| 1772 | /* |
| 1773 | * Try to acquire and then immediately release the console |
| 1774 | * semaphore. The release will print out buffers and wake up |
| 1775 | * /dev/kmsg and syslog() users. |
| 1776 | */ |
| 1777 | if (console_trylock_for_printk()) |
| 1778 | console_unlock(); |
| 1779 | preempt_enable(); |
| 1780 | lockdep_on(); |
| 1781 | } |
| 1782 | |
| 1783 | return printed_len; |
| 1784 | } |
| 1785 | EXPORT_SYMBOL(vprintk_emit); |
| 1786 | |
| 1787 | asmlinkage int vprintk(const char *fmt, va_list args) |
| 1788 | { |
| 1789 | return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
| 1790 | } |
| 1791 | EXPORT_SYMBOL(vprintk); |
| 1792 | |
| 1793 | asmlinkage int printk_emit(int facility, int level, |
| 1794 | const char *dict, size_t dictlen, |
| 1795 | const char *fmt, ...) |
| 1796 | { |
| 1797 | va_list args; |
| 1798 | int r; |
| 1799 | |
| 1800 | va_start(args, fmt); |
| 1801 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); |
| 1802 | va_end(args); |
| 1803 | |
| 1804 | return r; |
| 1805 | } |
| 1806 | EXPORT_SYMBOL(printk_emit); |
| 1807 | |
| 1808 | int vprintk_default(const char *fmt, va_list args) |
| 1809 | { |
| 1810 | int r; |
| 1811 | |
| 1812 | #ifdef CONFIG_KGDB_KDB |
| 1813 | if (unlikely(kdb_trap_printk)) { |
| 1814 | r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); |
| 1815 | return r; |
| 1816 | } |
| 1817 | #endif |
| 1818 | r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
| 1819 | |
| 1820 | return r; |
| 1821 | } |
| 1822 | EXPORT_SYMBOL_GPL(vprintk_default); |
| 1823 | |
| 1824 | /* |
| 1825 | * This allows printk to be diverted to another function per cpu. |
| 1826 | * This is useful for calling printk functions from within NMI |
| 1827 | * without worrying about race conditions that can lock up the |
| 1828 | * box. |
| 1829 | */ |
| 1830 | DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default; |
| 1831 | |
| 1832 | /** |
| 1833 | * printk - print a kernel message |
| 1834 | * @fmt: format string |
| 1835 | * |
| 1836 | * This is printk(). It can be called from any context. We want it to work. |
| 1837 | * |
| 1838 | * We try to grab the console_lock. If we succeed, it's easy - we log the |
| 1839 | * output and call the console drivers. If we fail to get the semaphore, we |
| 1840 | * place the output into the log buffer and return. The current holder of |
| 1841 | * the console_sem will notice the new output in console_unlock(); and will |
| 1842 | * send it to the consoles before releasing the lock. |
| 1843 | * |
| 1844 | * One effect of this deferred printing is that code which calls printk() and |
| 1845 | * then changes console_loglevel may break. This is because console_loglevel |
| 1846 | * is inspected when the actual printing occurs. |
| 1847 | * |
| 1848 | * See also: |
| 1849 | * printf(3) |
| 1850 | * |
| 1851 | * See the vsnprintf() documentation for format string extensions over C99. |
| 1852 | */ |
| 1853 | asmlinkage __visible int printk(const char *fmt, ...) |
| 1854 | { |
| 1855 | printk_func_t vprintk_func; |
| 1856 | va_list args; |
| 1857 | int r; |
| 1858 | |
| 1859 | va_start(args, fmt); |
| 1860 | |
| 1861 | /* |
| 1862 | * If a caller overrides the per_cpu printk_func, then it needs |
| 1863 | * to disable preemption when calling printk(). Otherwise |
| 1864 | * the printk_func should be set to the default. No need to |
| 1865 | * disable preemption here. |
| 1866 | */ |
| 1867 | vprintk_func = this_cpu_read(printk_func); |
| 1868 | r = vprintk_func(fmt, args); |
| 1869 | |
| 1870 | va_end(args); |
| 1871 | |
| 1872 | return r; |
| 1873 | } |
| 1874 | EXPORT_SYMBOL(printk); |
| 1875 | |
| 1876 | #else /* CONFIG_PRINTK */ |
| 1877 | |
| 1878 | #define LOG_LINE_MAX 0 |
| 1879 | #define PREFIX_MAX 0 |
| 1880 | |
| 1881 | static u64 syslog_seq; |
| 1882 | static u32 syslog_idx; |
| 1883 | static u64 console_seq; |
| 1884 | static u32 console_idx; |
| 1885 | static enum log_flags syslog_prev; |
| 1886 | static u64 log_first_seq; |
| 1887 | static u32 log_first_idx; |
| 1888 | static u64 log_next_seq; |
| 1889 | static enum log_flags console_prev; |
| 1890 | static struct cont { |
| 1891 | size_t len; |
| 1892 | size_t cons; |
| 1893 | u8 level; |
| 1894 | bool flushed:1; |
| 1895 | } cont; |
| 1896 | static struct printk_log *log_from_idx(u32 idx) { return NULL; } |
| 1897 | static u32 log_next(u32 idx) { return 0; } |
| 1898 | static void call_console_drivers(int level, const char *text, size_t len) {} |
| 1899 | static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, |
| 1900 | bool syslog, char *buf, size_t size) { return 0; } |
| 1901 | static size_t cont_print_text(char *text, size_t size) { return 0; } |
| 1902 | |
| 1903 | /* Still needs to be defined for users */ |
| 1904 | DEFINE_PER_CPU(printk_func_t, printk_func); |
| 1905 | |
| 1906 | #endif /* CONFIG_PRINTK */ |
| 1907 | |
| 1908 | #ifdef CONFIG_EARLY_PRINTK |
| 1909 | struct console *early_console; |
| 1910 | |
| 1911 | asmlinkage __visible void early_printk(const char *fmt, ...) |
| 1912 | { |
| 1913 | va_list ap; |
| 1914 | char buf[512]; |
| 1915 | int n; |
| 1916 | |
| 1917 | if (!early_console) |
| 1918 | return; |
| 1919 | |
| 1920 | va_start(ap, fmt); |
| 1921 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
| 1922 | va_end(ap); |
| 1923 | |
| 1924 | early_console->write(early_console, buf, n); |
| 1925 | } |
| 1926 | #endif |
| 1927 | |
| 1928 | static int __add_preferred_console(char *name, int idx, char *options, |
| 1929 | char *brl_options) |
| 1930 | { |
| 1931 | struct console_cmdline *c; |
| 1932 | int i; |
| 1933 | |
| 1934 | /* |
| 1935 | * See if this tty is not yet registered, and |
| 1936 | * if we have a slot free. |
| 1937 | */ |
| 1938 | for (i = 0, c = console_cmdline; |
| 1939 | i < MAX_CMDLINECONSOLES && c->name[0]; |
| 1940 | i++, c++) { |
| 1941 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
| 1942 | if (!brl_options) |
| 1943 | selected_console = i; |
| 1944 | return 0; |
| 1945 | } |
| 1946 | } |
| 1947 | if (i == MAX_CMDLINECONSOLES) |
| 1948 | return -E2BIG; |
| 1949 | if (!brl_options) |
| 1950 | selected_console = i; |
| 1951 | strlcpy(c->name, name, sizeof(c->name)); |
| 1952 | c->options = options; |
| 1953 | braille_set_options(c, brl_options); |
| 1954 | |
| 1955 | c->index = idx; |
| 1956 | return 0; |
| 1957 | } |
| 1958 | /* |
| 1959 | * Set up a console. Called via do_early_param() in init/main.c |
| 1960 | * for each "console=" parameter in the boot command line. |
| 1961 | */ |
| 1962 | static int __init console_setup(char *str) |
| 1963 | { |
| 1964 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
| 1965 | char *s, *options, *brl_options = NULL; |
| 1966 | int idx; |
| 1967 | |
| 1968 | if (_braille_console_setup(&str, &brl_options)) |
| 1969 | return 1; |
| 1970 | |
| 1971 | /* |
| 1972 | * Decode str into name, index, options. |
| 1973 | */ |
| 1974 | if (str[0] >= '0' && str[0] <= '9') { |
| 1975 | strcpy(buf, "ttyS"); |
| 1976 | strncpy(buf + 4, str, sizeof(buf) - 5); |
| 1977 | } else { |
| 1978 | strncpy(buf, str, sizeof(buf) - 1); |
| 1979 | } |
| 1980 | buf[sizeof(buf) - 1] = 0; |
| 1981 | options = strchr(str, ','); |
| 1982 | if (options) |
| 1983 | *(options++) = 0; |
| 1984 | #ifdef __sparc__ |
| 1985 | if (!strcmp(str, "ttya")) |
| 1986 | strcpy(buf, "ttyS0"); |
| 1987 | if (!strcmp(str, "ttyb")) |
| 1988 | strcpy(buf, "ttyS1"); |
| 1989 | #endif |
| 1990 | for (s = buf; *s; s++) |
| 1991 | if (isdigit(*s) || *s == ',') |
| 1992 | break; |
| 1993 | idx = simple_strtoul(s, NULL, 10); |
| 1994 | *s = 0; |
| 1995 | |
| 1996 | __add_preferred_console(buf, idx, options, brl_options); |
| 1997 | console_set_on_cmdline = 1; |
| 1998 | return 1; |
| 1999 | } |
| 2000 | __setup("console=", console_setup); |
| 2001 | |
| 2002 | /** |
| 2003 | * add_preferred_console - add a device to the list of preferred consoles. |
| 2004 | * @name: device name |
| 2005 | * @idx: device index |
| 2006 | * @options: options for this console |
| 2007 | * |
| 2008 | * The last preferred console added will be used for kernel messages |
| 2009 | * and stdin/out/err for init. Normally this is used by console_setup |
| 2010 | * above to handle user-supplied console arguments; however it can also |
| 2011 | * be used by arch-specific code either to override the user or more |
| 2012 | * commonly to provide a default console (ie from PROM variables) when |
| 2013 | * the user has not supplied one. |
| 2014 | */ |
| 2015 | int add_preferred_console(char *name, int idx, char *options) |
| 2016 | { |
| 2017 | return __add_preferred_console(name, idx, options, NULL); |
| 2018 | } |
| 2019 | |
| 2020 | bool console_suspend_enabled = true; |
| 2021 | EXPORT_SYMBOL(console_suspend_enabled); |
| 2022 | |
| 2023 | static int __init console_suspend_disable(char *str) |
| 2024 | { |
| 2025 | console_suspend_enabled = false; |
| 2026 | return 1; |
| 2027 | } |
| 2028 | __setup("no_console_suspend", console_suspend_disable); |
| 2029 | module_param_named(console_suspend, console_suspend_enabled, |
| 2030 | bool, S_IRUGO | S_IWUSR); |
| 2031 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" |
| 2032 | " and hibernate operations"); |
| 2033 | |
| 2034 | /** |
| 2035 | * suspend_console - suspend the console subsystem |
| 2036 | * |
| 2037 | * This disables printk() while we go into suspend states |
| 2038 | */ |
| 2039 | void suspend_console(void) |
| 2040 | { |
| 2041 | if (!console_suspend_enabled) |
| 2042 | return; |
| 2043 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
| 2044 | console_lock(); |
| 2045 | console_suspended = 1; |
| 2046 | up_console_sem(); |
| 2047 | } |
| 2048 | |
| 2049 | void resume_console(void) |
| 2050 | { |
| 2051 | if (!console_suspend_enabled) |
| 2052 | return; |
| 2053 | down_console_sem(); |
| 2054 | console_suspended = 0; |
| 2055 | console_unlock(); |
| 2056 | } |
| 2057 | |
| 2058 | /** |
| 2059 | * console_cpu_notify - print deferred console messages after CPU hotplug |
| 2060 | * @self: notifier struct |
| 2061 | * @action: CPU hotplug event |
| 2062 | * @hcpu: unused |
| 2063 | * |
| 2064 | * If printk() is called from a CPU that is not online yet, the messages |
| 2065 | * will be spooled but will not show up on the console. This function is |
| 2066 | * called when a new CPU comes online (or fails to come up), and ensures |
| 2067 | * that any such output gets printed. |
| 2068 | */ |
| 2069 | static int console_cpu_notify(struct notifier_block *self, |
| 2070 | unsigned long action, void *hcpu) |
| 2071 | { |
| 2072 | switch (action) { |
| 2073 | case CPU_ONLINE: |
| 2074 | case CPU_DEAD: |
| 2075 | case CPU_DOWN_FAILED: |
| 2076 | case CPU_UP_CANCELED: |
| 2077 | console_lock(); |
| 2078 | console_unlock(); |
| 2079 | } |
| 2080 | return NOTIFY_OK; |
| 2081 | } |
| 2082 | |
| 2083 | /** |
| 2084 | * console_lock - lock the console system for exclusive use. |
| 2085 | * |
| 2086 | * Acquires a lock which guarantees that the caller has |
| 2087 | * exclusive access to the console system and the console_drivers list. |
| 2088 | * |
| 2089 | * Can sleep, returns nothing. |
| 2090 | */ |
| 2091 | void console_lock(void) |
| 2092 | { |
| 2093 | might_sleep(); |
| 2094 | |
| 2095 | down_console_sem(); |
| 2096 | if (console_suspended) |
| 2097 | return; |
| 2098 | console_locked = 1; |
| 2099 | console_may_schedule = 1; |
| 2100 | } |
| 2101 | EXPORT_SYMBOL(console_lock); |
| 2102 | |
| 2103 | /** |
| 2104 | * console_trylock - try to lock the console system for exclusive use. |
| 2105 | * |
| 2106 | * Try to acquire a lock which guarantees that the caller has exclusive |
| 2107 | * access to the console system and the console_drivers list. |
| 2108 | * |
| 2109 | * returns 1 on success, and 0 on failure to acquire the lock. |
| 2110 | */ |
| 2111 | int console_trylock(void) |
| 2112 | { |
| 2113 | if (down_trylock_console_sem()) |
| 2114 | return 0; |
| 2115 | if (console_suspended) { |
| 2116 | up_console_sem(); |
| 2117 | return 0; |
| 2118 | } |
| 2119 | console_locked = 1; |
| 2120 | console_may_schedule = 0; |
| 2121 | return 1; |
| 2122 | } |
| 2123 | EXPORT_SYMBOL(console_trylock); |
| 2124 | |
| 2125 | int is_console_locked(void) |
| 2126 | { |
| 2127 | return console_locked; |
| 2128 | } |
| 2129 | |
| 2130 | static void console_cont_flush(char *text, size_t size) |
| 2131 | { |
| 2132 | unsigned long flags; |
| 2133 | size_t len; |
| 2134 | |
| 2135 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2136 | |
| 2137 | if (!cont.len) |
| 2138 | goto out; |
| 2139 | |
| 2140 | /* |
| 2141 | * We still queue earlier records, likely because the console was |
| 2142 | * busy. The earlier ones need to be printed before this one, we |
| 2143 | * did not flush any fragment so far, so just let it queue up. |
| 2144 | */ |
| 2145 | if (console_seq < log_next_seq && !cont.cons) |
| 2146 | goto out; |
| 2147 | |
| 2148 | len = cont_print_text(text, size); |
| 2149 | raw_spin_unlock(&logbuf_lock); |
| 2150 | stop_critical_timings(); |
| 2151 | call_console_drivers(cont.level, text, len); |
| 2152 | start_critical_timings(); |
| 2153 | local_irq_restore(flags); |
| 2154 | return; |
| 2155 | out: |
| 2156 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2157 | } |
| 2158 | |
| 2159 | /** |
| 2160 | * console_unlock - unlock the console system |
| 2161 | * |
| 2162 | * Releases the console_lock which the caller holds on the console system |
| 2163 | * and the console driver list. |
| 2164 | * |
| 2165 | * While the console_lock was held, console output may have been buffered |
| 2166 | * by printk(). If this is the case, console_unlock(); emits |
| 2167 | * the output prior to releasing the lock. |
| 2168 | * |
| 2169 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
| 2170 | * |
| 2171 | * console_unlock(); may be called from any context. |
| 2172 | */ |
| 2173 | void console_unlock(void) |
| 2174 | { |
| 2175 | static char text[LOG_LINE_MAX + PREFIX_MAX]; |
| 2176 | static u64 seen_seq; |
| 2177 | unsigned long flags; |
| 2178 | bool wake_klogd = false; |
| 2179 | bool retry; |
| 2180 | |
| 2181 | if (console_suspended) { |
| 2182 | up_console_sem(); |
| 2183 | return; |
| 2184 | } |
| 2185 | |
| 2186 | console_may_schedule = 0; |
| 2187 | |
| 2188 | /* flush buffered message fragment immediately to console */ |
| 2189 | console_cont_flush(text, sizeof(text)); |
| 2190 | again: |
| 2191 | for (;;) { |
| 2192 | struct printk_log *msg; |
| 2193 | size_t len; |
| 2194 | int level; |
| 2195 | |
| 2196 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2197 | if (seen_seq != log_next_seq) { |
| 2198 | wake_klogd = true; |
| 2199 | seen_seq = log_next_seq; |
| 2200 | } |
| 2201 | |
| 2202 | if (console_seq < log_first_seq) { |
| 2203 | len = sprintf(text, "** %u printk messages dropped ** ", |
| 2204 | (unsigned)(log_first_seq - console_seq)); |
| 2205 | |
| 2206 | /* messages are gone, move to first one */ |
| 2207 | console_seq = log_first_seq; |
| 2208 | console_idx = log_first_idx; |
| 2209 | console_prev = 0; |
| 2210 | } else { |
| 2211 | len = 0; |
| 2212 | } |
| 2213 | skip: |
| 2214 | if (console_seq == log_next_seq) |
| 2215 | break; |
| 2216 | |
| 2217 | msg = log_from_idx(console_idx); |
| 2218 | if (msg->flags & LOG_NOCONS) { |
| 2219 | /* |
| 2220 | * Skip record we have buffered and already printed |
| 2221 | * directly to the console when we received it. |
| 2222 | */ |
| 2223 | console_idx = log_next(console_idx); |
| 2224 | console_seq++; |
| 2225 | /* |
| 2226 | * We will get here again when we register a new |
| 2227 | * CON_PRINTBUFFER console. Clear the flag so we |
| 2228 | * will properly dump everything later. |
| 2229 | */ |
| 2230 | msg->flags &= ~LOG_NOCONS; |
| 2231 | console_prev = msg->flags; |
| 2232 | goto skip; |
| 2233 | } |
| 2234 | |
| 2235 | level = msg->level; |
| 2236 | len += msg_print_text(msg, console_prev, false, |
| 2237 | text + len, sizeof(text) - len); |
| 2238 | console_idx = log_next(console_idx); |
| 2239 | console_seq++; |
| 2240 | console_prev = msg->flags; |
| 2241 | raw_spin_unlock(&logbuf_lock); |
| 2242 | |
| 2243 | stop_critical_timings(); /* don't trace print latency */ |
| 2244 | call_console_drivers(level, text, len); |
| 2245 | start_critical_timings(); |
| 2246 | local_irq_restore(flags); |
| 2247 | } |
| 2248 | console_locked = 0; |
| 2249 | |
| 2250 | /* Release the exclusive_console once it is used */ |
| 2251 | if (unlikely(exclusive_console)) |
| 2252 | exclusive_console = NULL; |
| 2253 | |
| 2254 | raw_spin_unlock(&logbuf_lock); |
| 2255 | |
| 2256 | up_console_sem(); |
| 2257 | |
| 2258 | /* |
| 2259 | * Someone could have filled up the buffer again, so re-check if there's |
| 2260 | * something to flush. In case we cannot trylock the console_sem again, |
| 2261 | * there's a new owner and the console_unlock() from them will do the |
| 2262 | * flush, no worries. |
| 2263 | */ |
| 2264 | raw_spin_lock(&logbuf_lock); |
| 2265 | retry = console_seq != log_next_seq; |
| 2266 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2267 | |
| 2268 | if (retry && console_trylock()) |
| 2269 | goto again; |
| 2270 | |
| 2271 | if (wake_klogd) |
| 2272 | wake_up_klogd(); |
| 2273 | } |
| 2274 | EXPORT_SYMBOL(console_unlock); |
| 2275 | |
| 2276 | /** |
| 2277 | * console_conditional_schedule - yield the CPU if required |
| 2278 | * |
| 2279 | * If the console code is currently allowed to sleep, and |
| 2280 | * if this CPU should yield the CPU to another task, do |
| 2281 | * so here. |
| 2282 | * |
| 2283 | * Must be called within console_lock();. |
| 2284 | */ |
| 2285 | void __sched console_conditional_schedule(void) |
| 2286 | { |
| 2287 | if (console_may_schedule) |
| 2288 | cond_resched(); |
| 2289 | } |
| 2290 | EXPORT_SYMBOL(console_conditional_schedule); |
| 2291 | |
| 2292 | void console_unblank(void) |
| 2293 | { |
| 2294 | struct console *c; |
| 2295 | |
| 2296 | /* |
| 2297 | * console_unblank can no longer be called in interrupt context unless |
| 2298 | * oops_in_progress is set to 1.. |
| 2299 | */ |
| 2300 | if (oops_in_progress) { |
| 2301 | if (down_trylock_console_sem() != 0) |
| 2302 | return; |
| 2303 | } else |
| 2304 | console_lock(); |
| 2305 | |
| 2306 | console_locked = 1; |
| 2307 | console_may_schedule = 0; |
| 2308 | for_each_console(c) |
| 2309 | if ((c->flags & CON_ENABLED) && c->unblank) |
| 2310 | c->unblank(); |
| 2311 | console_unlock(); |
| 2312 | } |
| 2313 | |
| 2314 | /* |
| 2315 | * Return the console tty driver structure and its associated index |
| 2316 | */ |
| 2317 | struct tty_driver *console_device(int *index) |
| 2318 | { |
| 2319 | struct console *c; |
| 2320 | struct tty_driver *driver = NULL; |
| 2321 | |
| 2322 | console_lock(); |
| 2323 | for_each_console(c) { |
| 2324 | if (!c->device) |
| 2325 | continue; |
| 2326 | driver = c->device(c, index); |
| 2327 | if (driver) |
| 2328 | break; |
| 2329 | } |
| 2330 | console_unlock(); |
| 2331 | return driver; |
| 2332 | } |
| 2333 | |
| 2334 | /* |
| 2335 | * Prevent further output on the passed console device so that (for example) |
| 2336 | * serial drivers can disable console output before suspending a port, and can |
| 2337 | * re-enable output afterwards. |
| 2338 | */ |
| 2339 | void console_stop(struct console *console) |
| 2340 | { |
| 2341 | console_lock(); |
| 2342 | console->flags &= ~CON_ENABLED; |
| 2343 | console_unlock(); |
| 2344 | } |
| 2345 | EXPORT_SYMBOL(console_stop); |
| 2346 | |
| 2347 | void console_start(struct console *console) |
| 2348 | { |
| 2349 | console_lock(); |
| 2350 | console->flags |= CON_ENABLED; |
| 2351 | console_unlock(); |
| 2352 | } |
| 2353 | EXPORT_SYMBOL(console_start); |
| 2354 | |
| 2355 | static int __read_mostly keep_bootcon; |
| 2356 | |
| 2357 | static int __init keep_bootcon_setup(char *str) |
| 2358 | { |
| 2359 | keep_bootcon = 1; |
| 2360 | pr_info("debug: skip boot console de-registration.\n"); |
| 2361 | |
| 2362 | return 0; |
| 2363 | } |
| 2364 | |
| 2365 | early_param("keep_bootcon", keep_bootcon_setup); |
| 2366 | |
| 2367 | /* |
| 2368 | * The console driver calls this routine during kernel initialization |
| 2369 | * to register the console printing procedure with printk() and to |
| 2370 | * print any messages that were printed by the kernel before the |
| 2371 | * console driver was initialized. |
| 2372 | * |
| 2373 | * This can happen pretty early during the boot process (because of |
| 2374 | * early_printk) - sometimes before setup_arch() completes - be careful |
| 2375 | * of what kernel features are used - they may not be initialised yet. |
| 2376 | * |
| 2377 | * There are two types of consoles - bootconsoles (early_printk) and |
| 2378 | * "real" consoles (everything which is not a bootconsole) which are |
| 2379 | * handled differently. |
| 2380 | * - Any number of bootconsoles can be registered at any time. |
| 2381 | * - As soon as a "real" console is registered, all bootconsoles |
| 2382 | * will be unregistered automatically. |
| 2383 | * - Once a "real" console is registered, any attempt to register a |
| 2384 | * bootconsoles will be rejected |
| 2385 | */ |
| 2386 | void register_console(struct console *newcon) |
| 2387 | { |
| 2388 | int i; |
| 2389 | unsigned long flags; |
| 2390 | struct console *bcon = NULL; |
| 2391 | struct console_cmdline *c; |
| 2392 | |
| 2393 | if (console_drivers) |
| 2394 | for_each_console(bcon) |
| 2395 | if (WARN(bcon == newcon, |
| 2396 | "console '%s%d' already registered\n", |
| 2397 | bcon->name, bcon->index)) |
| 2398 | return; |
| 2399 | |
| 2400 | /* |
| 2401 | * before we register a new CON_BOOT console, make sure we don't |
| 2402 | * already have a valid console |
| 2403 | */ |
| 2404 | if (console_drivers && newcon->flags & CON_BOOT) { |
| 2405 | /* find the last or real console */ |
| 2406 | for_each_console(bcon) { |
| 2407 | if (!(bcon->flags & CON_BOOT)) { |
| 2408 | pr_info("Too late to register bootconsole %s%d\n", |
| 2409 | newcon->name, newcon->index); |
| 2410 | return; |
| 2411 | } |
| 2412 | } |
| 2413 | } |
| 2414 | |
| 2415 | if (console_drivers && console_drivers->flags & CON_BOOT) |
| 2416 | bcon = console_drivers; |
| 2417 | |
| 2418 | if (preferred_console < 0 || bcon || !console_drivers) |
| 2419 | preferred_console = selected_console; |
| 2420 | |
| 2421 | /* |
| 2422 | * See if we want to use this console driver. If we |
| 2423 | * didn't select a console we take the first one |
| 2424 | * that registers here. |
| 2425 | */ |
| 2426 | if (preferred_console < 0) { |
| 2427 | if (newcon->index < 0) |
| 2428 | newcon->index = 0; |
| 2429 | if (newcon->setup == NULL || |
| 2430 | newcon->setup(newcon, NULL) == 0) { |
| 2431 | newcon->flags |= CON_ENABLED; |
| 2432 | if (newcon->device) { |
| 2433 | newcon->flags |= CON_CONSDEV; |
| 2434 | preferred_console = 0; |
| 2435 | } |
| 2436 | } |
| 2437 | } |
| 2438 | |
| 2439 | /* |
| 2440 | * See if this console matches one we selected on |
| 2441 | * the command line. |
| 2442 | */ |
| 2443 | for (i = 0, c = console_cmdline; |
| 2444 | i < MAX_CMDLINECONSOLES && c->name[0]; |
| 2445 | i++, c++) { |
| 2446 | if (!newcon->match || |
| 2447 | newcon->match(newcon, c->name, c->index, c->options) != 0) { |
| 2448 | /* default matching */ |
| 2449 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); |
| 2450 | if (strcmp(c->name, newcon->name) != 0) |
| 2451 | continue; |
| 2452 | if (newcon->index >= 0 && |
| 2453 | newcon->index != c->index) |
| 2454 | continue; |
| 2455 | if (newcon->index < 0) |
| 2456 | newcon->index = c->index; |
| 2457 | |
| 2458 | if (_braille_register_console(newcon, c)) |
| 2459 | return; |
| 2460 | |
| 2461 | if (newcon->setup && |
| 2462 | newcon->setup(newcon, c->options) != 0) |
| 2463 | break; |
| 2464 | } |
| 2465 | |
| 2466 | newcon->flags |= CON_ENABLED; |
| 2467 | if (i == selected_console) { |
| 2468 | newcon->flags |= CON_CONSDEV; |
| 2469 | preferred_console = selected_console; |
| 2470 | } |
| 2471 | break; |
| 2472 | } |
| 2473 | |
| 2474 | if (!(newcon->flags & CON_ENABLED)) |
| 2475 | return; |
| 2476 | |
| 2477 | /* |
| 2478 | * If we have a bootconsole, and are switching to a real console, |
| 2479 | * don't print everything out again, since when the boot console, and |
| 2480 | * the real console are the same physical device, it's annoying to |
| 2481 | * see the beginning boot messages twice |
| 2482 | */ |
| 2483 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
| 2484 | newcon->flags &= ~CON_PRINTBUFFER; |
| 2485 | |
| 2486 | /* |
| 2487 | * Put this console in the list - keep the |
| 2488 | * preferred driver at the head of the list. |
| 2489 | */ |
| 2490 | console_lock(); |
| 2491 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
| 2492 | newcon->next = console_drivers; |
| 2493 | console_drivers = newcon; |
| 2494 | if (newcon->next) |
| 2495 | newcon->next->flags &= ~CON_CONSDEV; |
| 2496 | } else { |
| 2497 | newcon->next = console_drivers->next; |
| 2498 | console_drivers->next = newcon; |
| 2499 | } |
| 2500 | if (newcon->flags & CON_PRINTBUFFER) { |
| 2501 | /* |
| 2502 | * console_unlock(); will print out the buffered messages |
| 2503 | * for us. |
| 2504 | */ |
| 2505 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2506 | console_seq = syslog_seq; |
| 2507 | console_idx = syslog_idx; |
| 2508 | console_prev = syslog_prev; |
| 2509 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2510 | /* |
| 2511 | * We're about to replay the log buffer. Only do this to the |
| 2512 | * just-registered console to avoid excessive message spam to |
| 2513 | * the already-registered consoles. |
| 2514 | */ |
| 2515 | exclusive_console = newcon; |
| 2516 | } |
| 2517 | console_unlock(); |
| 2518 | console_sysfs_notify(); |
| 2519 | |
| 2520 | /* |
| 2521 | * By unregistering the bootconsoles after we enable the real console |
| 2522 | * we get the "console xxx enabled" message on all the consoles - |
| 2523 | * boot consoles, real consoles, etc - this is to ensure that end |
| 2524 | * users know there might be something in the kernel's log buffer that |
| 2525 | * went to the bootconsole (that they do not see on the real console) |
| 2526 | */ |
| 2527 | pr_info("%sconsole [%s%d] enabled\n", |
| 2528 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
| 2529 | newcon->name, newcon->index); |
| 2530 | if (bcon && |
| 2531 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
| 2532 | !keep_bootcon) { |
| 2533 | /* We need to iterate through all boot consoles, to make |
| 2534 | * sure we print everything out, before we unregister them. |
| 2535 | */ |
| 2536 | for_each_console(bcon) |
| 2537 | if (bcon->flags & CON_BOOT) |
| 2538 | unregister_console(bcon); |
| 2539 | } |
| 2540 | } |
| 2541 | EXPORT_SYMBOL(register_console); |
| 2542 | |
| 2543 | int unregister_console(struct console *console) |
| 2544 | { |
| 2545 | struct console *a, *b; |
| 2546 | int res; |
| 2547 | |
| 2548 | pr_info("%sconsole [%s%d] disabled\n", |
| 2549 | (console->flags & CON_BOOT) ? "boot" : "" , |
| 2550 | console->name, console->index); |
| 2551 | |
| 2552 | res = _braille_unregister_console(console); |
| 2553 | if (res) |
| 2554 | return res; |
| 2555 | |
| 2556 | res = 1; |
| 2557 | console_lock(); |
| 2558 | if (console_drivers == console) { |
| 2559 | console_drivers=console->next; |
| 2560 | res = 0; |
| 2561 | } else if (console_drivers) { |
| 2562 | for (a=console_drivers->next, b=console_drivers ; |
| 2563 | a; b=a, a=b->next) { |
| 2564 | if (a == console) { |
| 2565 | b->next = a->next; |
| 2566 | res = 0; |
| 2567 | break; |
| 2568 | } |
| 2569 | } |
| 2570 | } |
| 2571 | |
| 2572 | /* |
| 2573 | * If this isn't the last console and it has CON_CONSDEV set, we |
| 2574 | * need to set it on the next preferred console. |
| 2575 | */ |
| 2576 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
| 2577 | console_drivers->flags |= CON_CONSDEV; |
| 2578 | |
| 2579 | console->flags &= ~CON_ENABLED; |
| 2580 | console_unlock(); |
| 2581 | console_sysfs_notify(); |
| 2582 | return res; |
| 2583 | } |
| 2584 | EXPORT_SYMBOL(unregister_console); |
| 2585 | |
| 2586 | static int __init printk_late_init(void) |
| 2587 | { |
| 2588 | struct console *con; |
| 2589 | |
| 2590 | for_each_console(con) { |
| 2591 | if (!keep_bootcon && con->flags & CON_BOOT) { |
| 2592 | unregister_console(con); |
| 2593 | } |
| 2594 | } |
| 2595 | hotcpu_notifier(console_cpu_notify, 0); |
| 2596 | return 0; |
| 2597 | } |
| 2598 | late_initcall(printk_late_init); |
| 2599 | |
| 2600 | #if defined CONFIG_PRINTK |
| 2601 | /* |
| 2602 | * Delayed printk version, for scheduler-internal messages: |
| 2603 | */ |
| 2604 | #define PRINTK_PENDING_WAKEUP 0x01 |
| 2605 | #define PRINTK_PENDING_OUTPUT 0x02 |
| 2606 | |
| 2607 | static DEFINE_PER_CPU(int, printk_pending); |
| 2608 | |
| 2609 | static void wake_up_klogd_work_func(struct irq_work *irq_work) |
| 2610 | { |
| 2611 | int pending = __this_cpu_xchg(printk_pending, 0); |
| 2612 | |
| 2613 | if (pending & PRINTK_PENDING_OUTPUT) { |
| 2614 | /* If trylock fails, someone else is doing the printing */ |
| 2615 | if (console_trylock()) |
| 2616 | console_unlock(); |
| 2617 | } |
| 2618 | |
| 2619 | if (pending & PRINTK_PENDING_WAKEUP) |
| 2620 | wake_up_interruptible(&log_wait); |
| 2621 | } |
| 2622 | |
| 2623 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { |
| 2624 | .func = wake_up_klogd_work_func, |
| 2625 | .flags = IRQ_WORK_LAZY, |
| 2626 | }; |
| 2627 | |
| 2628 | void wake_up_klogd(void) |
| 2629 | { |
| 2630 | preempt_disable(); |
| 2631 | if (waitqueue_active(&log_wait)) { |
| 2632 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); |
| 2633 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
| 2634 | } |
| 2635 | preempt_enable(); |
| 2636 | } |
| 2637 | |
| 2638 | int printk_deferred(const char *fmt, ...) |
| 2639 | { |
| 2640 | va_list args; |
| 2641 | int r; |
| 2642 | |
| 2643 | preempt_disable(); |
| 2644 | va_start(args, fmt); |
| 2645 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); |
| 2646 | va_end(args); |
| 2647 | |
| 2648 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
| 2649 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
| 2650 | preempt_enable(); |
| 2651 | |
| 2652 | return r; |
| 2653 | } |
| 2654 | |
| 2655 | /* |
| 2656 | * printk rate limiting, lifted from the networking subsystem. |
| 2657 | * |
| 2658 | * This enforces a rate limit: not more than 10 kernel messages |
| 2659 | * every 5s to make a denial-of-service attack impossible. |
| 2660 | */ |
| 2661 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
| 2662 | |
| 2663 | int __printk_ratelimit(const char *func) |
| 2664 | { |
| 2665 | return ___ratelimit(&printk_ratelimit_state, func); |
| 2666 | } |
| 2667 | EXPORT_SYMBOL(__printk_ratelimit); |
| 2668 | |
| 2669 | /** |
| 2670 | * printk_timed_ratelimit - caller-controlled printk ratelimiting |
| 2671 | * @caller_jiffies: pointer to caller's state |
| 2672 | * @interval_msecs: minimum interval between prints |
| 2673 | * |
| 2674 | * printk_timed_ratelimit() returns true if more than @interval_msecs |
| 2675 | * milliseconds have elapsed since the last time printk_timed_ratelimit() |
| 2676 | * returned true. |
| 2677 | */ |
| 2678 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
| 2679 | unsigned int interval_msecs) |
| 2680 | { |
| 2681 | unsigned long elapsed = jiffies - *caller_jiffies; |
| 2682 | |
| 2683 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) |
| 2684 | return false; |
| 2685 | |
| 2686 | *caller_jiffies = jiffies; |
| 2687 | return true; |
| 2688 | } |
| 2689 | EXPORT_SYMBOL(printk_timed_ratelimit); |
| 2690 | |
| 2691 | static DEFINE_SPINLOCK(dump_list_lock); |
| 2692 | static LIST_HEAD(dump_list); |
| 2693 | |
| 2694 | /** |
| 2695 | * kmsg_dump_register - register a kernel log dumper. |
| 2696 | * @dumper: pointer to the kmsg_dumper structure |
| 2697 | * |
| 2698 | * Adds a kernel log dumper to the system. The dump callback in the |
| 2699 | * structure will be called when the kernel oopses or panics and must be |
| 2700 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
| 2701 | */ |
| 2702 | int kmsg_dump_register(struct kmsg_dumper *dumper) |
| 2703 | { |
| 2704 | unsigned long flags; |
| 2705 | int err = -EBUSY; |
| 2706 | |
| 2707 | /* The dump callback needs to be set */ |
| 2708 | if (!dumper->dump) |
| 2709 | return -EINVAL; |
| 2710 | |
| 2711 | spin_lock_irqsave(&dump_list_lock, flags); |
| 2712 | /* Don't allow registering multiple times */ |
| 2713 | if (!dumper->registered) { |
| 2714 | dumper->registered = 1; |
| 2715 | list_add_tail_rcu(&dumper->list, &dump_list); |
| 2716 | err = 0; |
| 2717 | } |
| 2718 | spin_unlock_irqrestore(&dump_list_lock, flags); |
| 2719 | |
| 2720 | return err; |
| 2721 | } |
| 2722 | EXPORT_SYMBOL_GPL(kmsg_dump_register); |
| 2723 | |
| 2724 | /** |
| 2725 | * kmsg_dump_unregister - unregister a kmsg dumper. |
| 2726 | * @dumper: pointer to the kmsg_dumper structure |
| 2727 | * |
| 2728 | * Removes a dump device from the system. Returns zero on success and |
| 2729 | * %-EINVAL otherwise. |
| 2730 | */ |
| 2731 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
| 2732 | { |
| 2733 | unsigned long flags; |
| 2734 | int err = -EINVAL; |
| 2735 | |
| 2736 | spin_lock_irqsave(&dump_list_lock, flags); |
| 2737 | if (dumper->registered) { |
| 2738 | dumper->registered = 0; |
| 2739 | list_del_rcu(&dumper->list); |
| 2740 | err = 0; |
| 2741 | } |
| 2742 | spin_unlock_irqrestore(&dump_list_lock, flags); |
| 2743 | synchronize_rcu(); |
| 2744 | |
| 2745 | return err; |
| 2746 | } |
| 2747 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
| 2748 | |
| 2749 | static bool always_kmsg_dump; |
| 2750 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); |
| 2751 | |
| 2752 | /** |
| 2753 | * kmsg_dump - dump kernel log to kernel message dumpers. |
| 2754 | * @reason: the reason (oops, panic etc) for dumping |
| 2755 | * |
| 2756 | * Call each of the registered dumper's dump() callback, which can |
| 2757 | * retrieve the kmsg records with kmsg_dump_get_line() or |
| 2758 | * kmsg_dump_get_buffer(). |
| 2759 | */ |
| 2760 | void kmsg_dump(enum kmsg_dump_reason reason) |
| 2761 | { |
| 2762 | struct kmsg_dumper *dumper; |
| 2763 | unsigned long flags; |
| 2764 | |
| 2765 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
| 2766 | return; |
| 2767 | |
| 2768 | rcu_read_lock(); |
| 2769 | list_for_each_entry_rcu(dumper, &dump_list, list) { |
| 2770 | if (dumper->max_reason && reason > dumper->max_reason) |
| 2771 | continue; |
| 2772 | |
| 2773 | /* initialize iterator with data about the stored records */ |
| 2774 | dumper->active = true; |
| 2775 | |
| 2776 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2777 | dumper->cur_seq = clear_seq; |
| 2778 | dumper->cur_idx = clear_idx; |
| 2779 | dumper->next_seq = log_next_seq; |
| 2780 | dumper->next_idx = log_next_idx; |
| 2781 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2782 | |
| 2783 | /* invoke dumper which will iterate over records */ |
| 2784 | dumper->dump(dumper, reason); |
| 2785 | |
| 2786 | /* reset iterator */ |
| 2787 | dumper->active = false; |
| 2788 | } |
| 2789 | rcu_read_unlock(); |
| 2790 | } |
| 2791 | |
| 2792 | /** |
| 2793 | * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) |
| 2794 | * @dumper: registered kmsg dumper |
| 2795 | * @syslog: include the "<4>" prefixes |
| 2796 | * @line: buffer to copy the line to |
| 2797 | * @size: maximum size of the buffer |
| 2798 | * @len: length of line placed into buffer |
| 2799 | * |
| 2800 | * Start at the beginning of the kmsg buffer, with the oldest kmsg |
| 2801 | * record, and copy one record into the provided buffer. |
| 2802 | * |
| 2803 | * Consecutive calls will return the next available record moving |
| 2804 | * towards the end of the buffer with the youngest messages. |
| 2805 | * |
| 2806 | * A return value of FALSE indicates that there are no more records to |
| 2807 | * read. |
| 2808 | * |
| 2809 | * The function is similar to kmsg_dump_get_line(), but grabs no locks. |
| 2810 | */ |
| 2811 | bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, |
| 2812 | char *line, size_t size, size_t *len) |
| 2813 | { |
| 2814 | struct printk_log *msg; |
| 2815 | size_t l = 0; |
| 2816 | bool ret = false; |
| 2817 | |
| 2818 | if (!dumper->active) |
| 2819 | goto out; |
| 2820 | |
| 2821 | if (dumper->cur_seq < log_first_seq) { |
| 2822 | /* messages are gone, move to first available one */ |
| 2823 | dumper->cur_seq = log_first_seq; |
| 2824 | dumper->cur_idx = log_first_idx; |
| 2825 | } |
| 2826 | |
| 2827 | /* last entry */ |
| 2828 | if (dumper->cur_seq >= log_next_seq) |
| 2829 | goto out; |
| 2830 | |
| 2831 | msg = log_from_idx(dumper->cur_idx); |
| 2832 | l = msg_print_text(msg, 0, syslog, line, size); |
| 2833 | |
| 2834 | dumper->cur_idx = log_next(dumper->cur_idx); |
| 2835 | dumper->cur_seq++; |
| 2836 | ret = true; |
| 2837 | out: |
| 2838 | if (len) |
| 2839 | *len = l; |
| 2840 | return ret; |
| 2841 | } |
| 2842 | |
| 2843 | /** |
| 2844 | * kmsg_dump_get_line - retrieve one kmsg log line |
| 2845 | * @dumper: registered kmsg dumper |
| 2846 | * @syslog: include the "<4>" prefixes |
| 2847 | * @line: buffer to copy the line to |
| 2848 | * @size: maximum size of the buffer |
| 2849 | * @len: length of line placed into buffer |
| 2850 | * |
| 2851 | * Start at the beginning of the kmsg buffer, with the oldest kmsg |
| 2852 | * record, and copy one record into the provided buffer. |
| 2853 | * |
| 2854 | * Consecutive calls will return the next available record moving |
| 2855 | * towards the end of the buffer with the youngest messages. |
| 2856 | * |
| 2857 | * A return value of FALSE indicates that there are no more records to |
| 2858 | * read. |
| 2859 | */ |
| 2860 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, |
| 2861 | char *line, size_t size, size_t *len) |
| 2862 | { |
| 2863 | unsigned long flags; |
| 2864 | bool ret; |
| 2865 | |
| 2866 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2867 | ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); |
| 2868 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2869 | |
| 2870 | return ret; |
| 2871 | } |
| 2872 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); |
| 2873 | |
| 2874 | /** |
| 2875 | * kmsg_dump_get_buffer - copy kmsg log lines |
| 2876 | * @dumper: registered kmsg dumper |
| 2877 | * @syslog: include the "<4>" prefixes |
| 2878 | * @buf: buffer to copy the line to |
| 2879 | * @size: maximum size of the buffer |
| 2880 | * @len: length of line placed into buffer |
| 2881 | * |
| 2882 | * Start at the end of the kmsg buffer and fill the provided buffer |
| 2883 | * with as many of the the *youngest* kmsg records that fit into it. |
| 2884 | * If the buffer is large enough, all available kmsg records will be |
| 2885 | * copied with a single call. |
| 2886 | * |
| 2887 | * Consecutive calls will fill the buffer with the next block of |
| 2888 | * available older records, not including the earlier retrieved ones. |
| 2889 | * |
| 2890 | * A return value of FALSE indicates that there are no more records to |
| 2891 | * read. |
| 2892 | */ |
| 2893 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, |
| 2894 | char *buf, size_t size, size_t *len) |
| 2895 | { |
| 2896 | unsigned long flags; |
| 2897 | u64 seq; |
| 2898 | u32 idx; |
| 2899 | u64 next_seq; |
| 2900 | u32 next_idx; |
| 2901 | enum log_flags prev; |
| 2902 | size_t l = 0; |
| 2903 | bool ret = false; |
| 2904 | |
| 2905 | if (!dumper->active) |
| 2906 | goto out; |
| 2907 | |
| 2908 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2909 | if (dumper->cur_seq < log_first_seq) { |
| 2910 | /* messages are gone, move to first available one */ |
| 2911 | dumper->cur_seq = log_first_seq; |
| 2912 | dumper->cur_idx = log_first_idx; |
| 2913 | } |
| 2914 | |
| 2915 | /* last entry */ |
| 2916 | if (dumper->cur_seq >= dumper->next_seq) { |
| 2917 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2918 | goto out; |
| 2919 | } |
| 2920 | |
| 2921 | /* calculate length of entire buffer */ |
| 2922 | seq = dumper->cur_seq; |
| 2923 | idx = dumper->cur_idx; |
| 2924 | prev = 0; |
| 2925 | while (seq < dumper->next_seq) { |
| 2926 | struct printk_log *msg = log_from_idx(idx); |
| 2927 | |
| 2928 | l += msg_print_text(msg, prev, true, NULL, 0); |
| 2929 | idx = log_next(idx); |
| 2930 | seq++; |
| 2931 | prev = msg->flags; |
| 2932 | } |
| 2933 | |
| 2934 | /* move first record forward until length fits into the buffer */ |
| 2935 | seq = dumper->cur_seq; |
| 2936 | idx = dumper->cur_idx; |
| 2937 | prev = 0; |
| 2938 | while (l > size && seq < dumper->next_seq) { |
| 2939 | struct printk_log *msg = log_from_idx(idx); |
| 2940 | |
| 2941 | l -= msg_print_text(msg, prev, true, NULL, 0); |
| 2942 | idx = log_next(idx); |
| 2943 | seq++; |
| 2944 | prev = msg->flags; |
| 2945 | } |
| 2946 | |
| 2947 | /* last message in next interation */ |
| 2948 | next_seq = seq; |
| 2949 | next_idx = idx; |
| 2950 | |
| 2951 | l = 0; |
| 2952 | while (seq < dumper->next_seq) { |
| 2953 | struct printk_log *msg = log_from_idx(idx); |
| 2954 | |
| 2955 | l += msg_print_text(msg, prev, syslog, buf + l, size - l); |
| 2956 | idx = log_next(idx); |
| 2957 | seq++; |
| 2958 | prev = msg->flags; |
| 2959 | } |
| 2960 | |
| 2961 | dumper->next_seq = next_seq; |
| 2962 | dumper->next_idx = next_idx; |
| 2963 | ret = true; |
| 2964 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2965 | out: |
| 2966 | if (len) |
| 2967 | *len = l; |
| 2968 | return ret; |
| 2969 | } |
| 2970 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); |
| 2971 | |
| 2972 | /** |
| 2973 | * kmsg_dump_rewind_nolock - reset the interator (unlocked version) |
| 2974 | * @dumper: registered kmsg dumper |
| 2975 | * |
| 2976 | * Reset the dumper's iterator so that kmsg_dump_get_line() and |
| 2977 | * kmsg_dump_get_buffer() can be called again and used multiple |
| 2978 | * times within the same dumper.dump() callback. |
| 2979 | * |
| 2980 | * The function is similar to kmsg_dump_rewind(), but grabs no locks. |
| 2981 | */ |
| 2982 | void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) |
| 2983 | { |
| 2984 | dumper->cur_seq = clear_seq; |
| 2985 | dumper->cur_idx = clear_idx; |
| 2986 | dumper->next_seq = log_next_seq; |
| 2987 | dumper->next_idx = log_next_idx; |
| 2988 | } |
| 2989 | |
| 2990 | /** |
| 2991 | * kmsg_dump_rewind - reset the interator |
| 2992 | * @dumper: registered kmsg dumper |
| 2993 | * |
| 2994 | * Reset the dumper's iterator so that kmsg_dump_get_line() and |
| 2995 | * kmsg_dump_get_buffer() can be called again and used multiple |
| 2996 | * times within the same dumper.dump() callback. |
| 2997 | */ |
| 2998 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) |
| 2999 | { |
| 3000 | unsigned long flags; |
| 3001 | |
| 3002 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 3003 | kmsg_dump_rewind_nolock(dumper); |
| 3004 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 3005 | } |
| 3006 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
| 3007 | |
| 3008 | static char dump_stack_arch_desc_str[128]; |
| 3009 | |
| 3010 | /** |
| 3011 | * dump_stack_set_arch_desc - set arch-specific str to show with task dumps |
| 3012 | * @fmt: printf-style format string |
| 3013 | * @...: arguments for the format string |
| 3014 | * |
| 3015 | * The configured string will be printed right after utsname during task |
| 3016 | * dumps. Usually used to add arch-specific system identifiers. If an |
| 3017 | * arch wants to make use of such an ID string, it should initialize this |
| 3018 | * as soon as possible during boot. |
| 3019 | */ |
| 3020 | void __init dump_stack_set_arch_desc(const char *fmt, ...) |
| 3021 | { |
| 3022 | va_list args; |
| 3023 | |
| 3024 | va_start(args, fmt); |
| 3025 | vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str), |
| 3026 | fmt, args); |
| 3027 | va_end(args); |
| 3028 | } |
| 3029 | |
| 3030 | /** |
| 3031 | * dump_stack_print_info - print generic debug info for dump_stack() |
| 3032 | * @log_lvl: log level |
| 3033 | * |
| 3034 | * Arch-specific dump_stack() implementations can use this function to |
| 3035 | * print out the same debug information as the generic dump_stack(). |
| 3036 | */ |
| 3037 | void dump_stack_print_info(const char *log_lvl) |
| 3038 | { |
| 3039 | printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n", |
| 3040 | log_lvl, raw_smp_processor_id(), current->pid, current->comm, |
| 3041 | print_tainted(), init_utsname()->release, |
| 3042 | (int)strcspn(init_utsname()->version, " "), |
| 3043 | init_utsname()->version); |
| 3044 | |
| 3045 | if (dump_stack_arch_desc_str[0] != '\0') |
| 3046 | printk("%sHardware name: %s\n", |
| 3047 | log_lvl, dump_stack_arch_desc_str); |
| 3048 | |
| 3049 | print_worker_info(log_lvl, current); |
| 3050 | } |
| 3051 | |
| 3052 | /** |
| 3053 | * show_regs_print_info - print generic debug info for show_regs() |
| 3054 | * @log_lvl: log level |
| 3055 | * |
| 3056 | * show_regs() implementations can use this function to print out generic |
| 3057 | * debug information. |
| 3058 | */ |
| 3059 | void show_regs_print_info(const char *log_lvl) |
| 3060 | { |
| 3061 | dump_stack_print_info(log_lvl); |
| 3062 | |
| 3063 | printk("%stask: %p ti: %p task.ti: %p\n", |
| 3064 | log_lvl, current, current_thread_info(), |
| 3065 | task_thread_info(current)); |
| 3066 | } |
| 3067 | |
| 3068 | #endif |