| 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 | |
| 46 | #include <asm/uaccess.h> |
| 47 | |
| 48 | #define CREATE_TRACE_POINTS |
| 49 | #include <trace/events/printk.h> |
| 50 | |
| 51 | /* |
| 52 | * Architectures can override it: |
| 53 | */ |
| 54 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
| 55 | { |
| 56 | } |
| 57 | |
| 58 | /* printk's without a loglevel use this.. */ |
| 59 | #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
| 60 | |
| 61 | /* We show everything that is MORE important than this.. */ |
| 62 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ |
| 63 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ |
| 64 | |
| 65 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
| 66 | |
| 67 | int console_printk[4] = { |
| 68 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ |
| 69 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ |
| 70 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ |
| 71 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ |
| 72 | }; |
| 73 | |
| 74 | /* |
| 75 | * Low level drivers may need that to know if they can schedule in |
| 76 | * their unblank() callback or not. So let's export it. |
| 77 | */ |
| 78 | int oops_in_progress; |
| 79 | EXPORT_SYMBOL(oops_in_progress); |
| 80 | |
| 81 | /* |
| 82 | * console_sem protects the console_drivers list, and also |
| 83 | * provides serialisation for access to the entire console |
| 84 | * driver system. |
| 85 | */ |
| 86 | static DEFINE_SEMAPHORE(console_sem); |
| 87 | struct console *console_drivers; |
| 88 | EXPORT_SYMBOL_GPL(console_drivers); |
| 89 | |
| 90 | /* |
| 91 | * This is used for debugging the mess that is the VT code by |
| 92 | * keeping track if we have the console semaphore held. It's |
| 93 | * definitely not the perfect debug tool (we don't know if _WE_ |
| 94 | * hold it are racing, but it helps tracking those weird code |
| 95 | * path in the console code where we end up in places I want |
| 96 | * locked without the console sempahore held |
| 97 | */ |
| 98 | static int console_locked, console_suspended; |
| 99 | |
| 100 | /* |
| 101 | * If exclusive_console is non-NULL then only this console is to be printed to. |
| 102 | */ |
| 103 | static struct console *exclusive_console; |
| 104 | |
| 105 | /* |
| 106 | * Array of consoles built from command line options (console=) |
| 107 | */ |
| 108 | struct console_cmdline |
| 109 | { |
| 110 | char name[8]; /* Name of the driver */ |
| 111 | int index; /* Minor dev. to use */ |
| 112 | char *options; /* Options for the driver */ |
| 113 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| 114 | char *brl_options; /* Options for braille driver */ |
| 115 | #endif |
| 116 | }; |
| 117 | |
| 118 | #define MAX_CMDLINECONSOLES 8 |
| 119 | |
| 120 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; |
| 121 | static int selected_console = -1; |
| 122 | static int preferred_console = -1; |
| 123 | int console_set_on_cmdline; |
| 124 | EXPORT_SYMBOL(console_set_on_cmdline); |
| 125 | |
| 126 | /* Flag: console code may call schedule() */ |
| 127 | static int console_may_schedule; |
| 128 | |
| 129 | /* |
| 130 | * The printk log buffer consists of a chain of concatenated variable |
| 131 | * length records. Every record starts with a record header, containing |
| 132 | * the overall length of the record. |
| 133 | * |
| 134 | * The heads to the first and last entry in the buffer, as well as the |
| 135 | * sequence numbers of these both entries are maintained when messages |
| 136 | * are stored.. |
| 137 | * |
| 138 | * If the heads indicate available messages, the length in the header |
| 139 | * tells the start next message. A length == 0 for the next message |
| 140 | * indicates a wrap-around to the beginning of the buffer. |
| 141 | * |
| 142 | * Every record carries the monotonic timestamp in microseconds, as well as |
| 143 | * the standard userspace syslog level and syslog facility. The usual |
| 144 | * kernel messages use LOG_KERN; userspace-injected messages always carry |
| 145 | * a matching syslog facility, by default LOG_USER. The origin of every |
| 146 | * message can be reliably determined that way. |
| 147 | * |
| 148 | * The human readable log message directly follows the message header. The |
| 149 | * length of the message text is stored in the header, the stored message |
| 150 | * is not terminated. |
| 151 | * |
| 152 | * Optionally, a message can carry a dictionary of properties (key/value pairs), |
| 153 | * to provide userspace with a machine-readable message context. |
| 154 | * |
| 155 | * Examples for well-defined, commonly used property names are: |
| 156 | * DEVICE=b12:8 device identifier |
| 157 | * b12:8 block dev_t |
| 158 | * c127:3 char dev_t |
| 159 | * n8 netdev ifindex |
| 160 | * +sound:card0 subsystem:devname |
| 161 | * SUBSYSTEM=pci driver-core subsystem name |
| 162 | * |
| 163 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value |
| 164 | * follows directly after a '=' character. Every property is terminated by |
| 165 | * a '\0' character. The last property is not terminated. |
| 166 | * |
| 167 | * Example of a message structure: |
| 168 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec |
| 169 | * 0008 34 00 record is 52 bytes long |
| 170 | * 000a 0b 00 text is 11 bytes long |
| 171 | * 000c 1f 00 dictionary is 23 bytes long |
| 172 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) |
| 173 | * 0010 69 74 27 73 20 61 20 6c "it's a l" |
| 174 | * 69 6e 65 "ine" |
| 175 | * 001b 44 45 56 49 43 "DEVIC" |
| 176 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" |
| 177 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" |
| 178 | * 67 "g" |
| 179 | * 0032 00 00 00 padding to next message header |
| 180 | * |
| 181 | * The 'struct log' buffer header must never be directly exported to |
| 182 | * userspace, it is a kernel-private implementation detail that might |
| 183 | * need to be changed in the future, when the requirements change. |
| 184 | * |
| 185 | * /dev/kmsg exports the structured data in the following line format: |
| 186 | * "level,sequnum,timestamp;<message text>\n" |
| 187 | * |
| 188 | * The optional key/value pairs are attached as continuation lines starting |
| 189 | * with a space character and terminated by a newline. All possible |
| 190 | * non-prinatable characters are escaped in the "\xff" notation. |
| 191 | * |
| 192 | * Users of the export format should ignore possible additional values |
| 193 | * separated by ',', and find the message after the ';' character. |
| 194 | */ |
| 195 | |
| 196 | struct log { |
| 197 | u64 ts_nsec; /* timestamp in nanoseconds */ |
| 198 | u16 len; /* length of entire record */ |
| 199 | u16 text_len; /* length of text buffer */ |
| 200 | u16 dict_len; /* length of dictionary buffer */ |
| 201 | u16 level; /* syslog level + facility */ |
| 202 | }; |
| 203 | |
| 204 | /* |
| 205 | * The logbuf_lock protects kmsg buffer, indices, counters. It is also |
| 206 | * used in interesting ways to provide interlocking in console_unlock(); |
| 207 | */ |
| 208 | static DEFINE_RAW_SPINLOCK(logbuf_lock); |
| 209 | |
| 210 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
| 211 | static u64 syslog_seq; |
| 212 | static u32 syslog_idx; |
| 213 | |
| 214 | /* index and sequence number of the first record stored in the buffer */ |
| 215 | static u64 log_first_seq; |
| 216 | static u32 log_first_idx; |
| 217 | |
| 218 | /* index and sequence number of the next record to store in the buffer */ |
| 219 | static u64 log_next_seq; |
| 220 | #ifdef CONFIG_PRINTK |
| 221 | static u32 log_next_idx; |
| 222 | |
| 223 | /* the next printk record to read after the last 'clear' command */ |
| 224 | static u64 clear_seq; |
| 225 | static u32 clear_idx; |
| 226 | |
| 227 | #define LOG_LINE_MAX 1024 |
| 228 | |
| 229 | /* record buffer */ |
| 230 | #if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) |
| 231 | #define LOG_ALIGN 4 |
| 232 | #else |
| 233 | #define LOG_ALIGN 8 |
| 234 | #endif |
| 235 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
| 236 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
| 237 | static char *log_buf = __log_buf; |
| 238 | static u32 log_buf_len = __LOG_BUF_LEN; |
| 239 | |
| 240 | /* cpu currently holding logbuf_lock */ |
| 241 | static volatile unsigned int logbuf_cpu = UINT_MAX; |
| 242 | |
| 243 | /* human readable text of the record */ |
| 244 | static char *log_text(const struct log *msg) |
| 245 | { |
| 246 | return (char *)msg + sizeof(struct log); |
| 247 | } |
| 248 | |
| 249 | /* optional key/value pair dictionary attached to the record */ |
| 250 | static char *log_dict(const struct log *msg) |
| 251 | { |
| 252 | return (char *)msg + sizeof(struct log) + msg->text_len; |
| 253 | } |
| 254 | |
| 255 | /* get record by index; idx must point to valid msg */ |
| 256 | static struct log *log_from_idx(u32 idx) |
| 257 | { |
| 258 | struct log *msg = (struct log *)(log_buf + idx); |
| 259 | |
| 260 | /* |
| 261 | * A length == 0 record is the end of buffer marker. Wrap around and |
| 262 | * read the message at the start of the buffer. |
| 263 | */ |
| 264 | if (!msg->len) |
| 265 | return (struct log *)log_buf; |
| 266 | return msg; |
| 267 | } |
| 268 | |
| 269 | /* get next record; idx must point to valid msg */ |
| 270 | static u32 log_next(u32 idx) |
| 271 | { |
| 272 | struct log *msg = (struct log *)(log_buf + idx); |
| 273 | |
| 274 | /* length == 0 indicates the end of the buffer; wrap */ |
| 275 | /* |
| 276 | * A length == 0 record is the end of buffer marker. Wrap around and |
| 277 | * read the message at the start of the buffer as *this* one, and |
| 278 | * return the one after that. |
| 279 | */ |
| 280 | if (!msg->len) { |
| 281 | msg = (struct log *)log_buf; |
| 282 | return msg->len; |
| 283 | } |
| 284 | return idx + msg->len; |
| 285 | } |
| 286 | |
| 287 | /* insert record into the buffer, discard old ones, update heads */ |
| 288 | static void log_store(int facility, int level, |
| 289 | const char *dict, u16 dict_len, |
| 290 | const char *text, u16 text_len) |
| 291 | { |
| 292 | struct log *msg; |
| 293 | u32 size, pad_len; |
| 294 | |
| 295 | /* number of '\0' padding bytes to next message */ |
| 296 | size = sizeof(struct log) + text_len + dict_len; |
| 297 | pad_len = (-size) & (LOG_ALIGN - 1); |
| 298 | size += pad_len; |
| 299 | |
| 300 | while (log_first_seq < log_next_seq) { |
| 301 | u32 free; |
| 302 | |
| 303 | if (log_next_idx > log_first_idx) |
| 304 | free = max(log_buf_len - log_next_idx, log_first_idx); |
| 305 | else |
| 306 | free = log_first_idx - log_next_idx; |
| 307 | |
| 308 | if (free > size + sizeof(struct log)) |
| 309 | break; |
| 310 | |
| 311 | /* drop old messages until we have enough contiuous space */ |
| 312 | log_first_idx = log_next(log_first_idx); |
| 313 | log_first_seq++; |
| 314 | } |
| 315 | |
| 316 | if (log_next_idx + size + sizeof(struct log) >= log_buf_len) { |
| 317 | /* |
| 318 | * This message + an additional empty header does not fit |
| 319 | * at the end of the buffer. Add an empty header with len == 0 |
| 320 | * to signify a wrap around. |
| 321 | */ |
| 322 | memset(log_buf + log_next_idx, 0, sizeof(struct log)); |
| 323 | log_next_idx = 0; |
| 324 | } |
| 325 | |
| 326 | /* fill message */ |
| 327 | msg = (struct log *)(log_buf + log_next_idx); |
| 328 | memcpy(log_text(msg), text, text_len); |
| 329 | msg->text_len = text_len; |
| 330 | memcpy(log_dict(msg), dict, dict_len); |
| 331 | msg->dict_len = dict_len; |
| 332 | msg->level = (facility << 3) | (level & 7); |
| 333 | msg->ts_nsec = local_clock(); |
| 334 | memset(log_dict(msg) + dict_len, 0, pad_len); |
| 335 | msg->len = sizeof(struct log) + text_len + dict_len + pad_len; |
| 336 | |
| 337 | /* insert message */ |
| 338 | log_next_idx += msg->len; |
| 339 | log_next_seq++; |
| 340 | } |
| 341 | |
| 342 | /* /dev/kmsg - userspace message inject/listen interface */ |
| 343 | struct devkmsg_user { |
| 344 | u64 seq; |
| 345 | u32 idx; |
| 346 | struct mutex lock; |
| 347 | char buf[8192]; |
| 348 | }; |
| 349 | |
| 350 | static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv, |
| 351 | unsigned long count, loff_t pos) |
| 352 | { |
| 353 | char *buf, *line; |
| 354 | int i; |
| 355 | int level = default_message_loglevel; |
| 356 | int facility = 1; /* LOG_USER */ |
| 357 | size_t len = iov_length(iv, count); |
| 358 | ssize_t ret = len; |
| 359 | |
| 360 | if (len > LOG_LINE_MAX) |
| 361 | return -EINVAL; |
| 362 | buf = kmalloc(len+1, GFP_KERNEL); |
| 363 | if (buf == NULL) |
| 364 | return -ENOMEM; |
| 365 | |
| 366 | line = buf; |
| 367 | for (i = 0; i < count; i++) { |
| 368 | if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) |
| 369 | goto out; |
| 370 | line += iv[i].iov_len; |
| 371 | } |
| 372 | |
| 373 | /* |
| 374 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace |
| 375 | * the decimal value represents 32bit, the lower 3 bit are the log |
| 376 | * level, the rest are the log facility. |
| 377 | * |
| 378 | * If no prefix or no userspace facility is specified, we |
| 379 | * enforce LOG_USER, to be able to reliably distinguish |
| 380 | * kernel-generated messages from userspace-injected ones. |
| 381 | */ |
| 382 | line = buf; |
| 383 | if (line[0] == '<') { |
| 384 | char *endp = NULL; |
| 385 | |
| 386 | i = simple_strtoul(line+1, &endp, 10); |
| 387 | if (endp && endp[0] == '>') { |
| 388 | level = i & 7; |
| 389 | if (i >> 3) |
| 390 | facility = i >> 3; |
| 391 | endp++; |
| 392 | len -= endp - line; |
| 393 | line = endp; |
| 394 | } |
| 395 | } |
| 396 | line[len] = '\0'; |
| 397 | |
| 398 | printk_emit(facility, level, NULL, 0, "%s", line); |
| 399 | out: |
| 400 | kfree(buf); |
| 401 | return ret; |
| 402 | } |
| 403 | |
| 404 | static ssize_t devkmsg_read(struct file *file, char __user *buf, |
| 405 | size_t count, loff_t *ppos) |
| 406 | { |
| 407 | struct devkmsg_user *user = file->private_data; |
| 408 | struct log *msg; |
| 409 | u64 ts_usec; |
| 410 | size_t i; |
| 411 | size_t len; |
| 412 | ssize_t ret; |
| 413 | |
| 414 | if (!user) |
| 415 | return -EBADF; |
| 416 | |
| 417 | mutex_lock(&user->lock); |
| 418 | raw_spin_lock(&logbuf_lock); |
| 419 | while (user->seq == log_next_seq) { |
| 420 | if (file->f_flags & O_NONBLOCK) { |
| 421 | ret = -EAGAIN; |
| 422 | raw_spin_unlock(&logbuf_lock); |
| 423 | goto out; |
| 424 | } |
| 425 | |
| 426 | raw_spin_unlock(&logbuf_lock); |
| 427 | ret = wait_event_interruptible(log_wait, |
| 428 | user->seq != log_next_seq); |
| 429 | if (ret) |
| 430 | goto out; |
| 431 | raw_spin_lock(&logbuf_lock); |
| 432 | } |
| 433 | |
| 434 | if (user->seq < log_first_seq) { |
| 435 | /* our last seen message is gone, return error and reset */ |
| 436 | user->idx = log_first_idx; |
| 437 | user->seq = log_first_seq; |
| 438 | ret = -EPIPE; |
| 439 | raw_spin_unlock(&logbuf_lock); |
| 440 | goto out; |
| 441 | } |
| 442 | |
| 443 | msg = log_from_idx(user->idx); |
| 444 | ts_usec = msg->ts_nsec; |
| 445 | do_div(ts_usec, 1000); |
| 446 | len = sprintf(user->buf, "%u,%llu,%llu;", |
| 447 | msg->level, user->seq, ts_usec); |
| 448 | |
| 449 | /* escape non-printable characters */ |
| 450 | for (i = 0; i < msg->text_len; i++) { |
| 451 | unsigned char c = log_text(msg)[i]; |
| 452 | |
| 453 | if (c < ' ' || c >= 128) |
| 454 | len += sprintf(user->buf + len, "\\x%02x", c); |
| 455 | else |
| 456 | user->buf[len++] = c; |
| 457 | } |
| 458 | user->buf[len++] = '\n'; |
| 459 | |
| 460 | if (msg->dict_len) { |
| 461 | bool line = true; |
| 462 | |
| 463 | for (i = 0; i < msg->dict_len; i++) { |
| 464 | unsigned char c = log_dict(msg)[i]; |
| 465 | |
| 466 | if (line) { |
| 467 | user->buf[len++] = ' '; |
| 468 | line = false; |
| 469 | } |
| 470 | |
| 471 | if (c == '\0') { |
| 472 | user->buf[len++] = '\n'; |
| 473 | line = true; |
| 474 | continue; |
| 475 | } |
| 476 | |
| 477 | if (c < ' ' || c >= 128) { |
| 478 | len += sprintf(user->buf + len, "\\x%02x", c); |
| 479 | continue; |
| 480 | } |
| 481 | |
| 482 | user->buf[len++] = c; |
| 483 | } |
| 484 | user->buf[len++] = '\n'; |
| 485 | } |
| 486 | |
| 487 | user->idx = log_next(user->idx); |
| 488 | user->seq++; |
| 489 | raw_spin_unlock(&logbuf_lock); |
| 490 | |
| 491 | if (len > count) { |
| 492 | ret = -EINVAL; |
| 493 | goto out; |
| 494 | } |
| 495 | |
| 496 | if (copy_to_user(buf, user->buf, len)) { |
| 497 | ret = -EFAULT; |
| 498 | goto out; |
| 499 | } |
| 500 | ret = len; |
| 501 | out: |
| 502 | mutex_unlock(&user->lock); |
| 503 | return ret; |
| 504 | } |
| 505 | |
| 506 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) |
| 507 | { |
| 508 | struct devkmsg_user *user = file->private_data; |
| 509 | loff_t ret = 0; |
| 510 | |
| 511 | if (!user) |
| 512 | return -EBADF; |
| 513 | if (offset) |
| 514 | return -ESPIPE; |
| 515 | |
| 516 | raw_spin_lock(&logbuf_lock); |
| 517 | switch (whence) { |
| 518 | case SEEK_SET: |
| 519 | /* the first record */ |
| 520 | user->idx = log_first_idx; |
| 521 | user->seq = log_first_seq; |
| 522 | break; |
| 523 | case SEEK_DATA: |
| 524 | /* |
| 525 | * The first record after the last SYSLOG_ACTION_CLEAR, |
| 526 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself |
| 527 | * changes no global state, and does not clear anything. |
| 528 | */ |
| 529 | user->idx = clear_idx; |
| 530 | user->seq = clear_seq; |
| 531 | break; |
| 532 | case SEEK_END: |
| 533 | /* after the last record */ |
| 534 | user->idx = log_next_idx; |
| 535 | user->seq = log_next_seq; |
| 536 | break; |
| 537 | default: |
| 538 | ret = -EINVAL; |
| 539 | } |
| 540 | raw_spin_unlock(&logbuf_lock); |
| 541 | return ret; |
| 542 | } |
| 543 | |
| 544 | static unsigned int devkmsg_poll(struct file *file, poll_table *wait) |
| 545 | { |
| 546 | struct devkmsg_user *user = file->private_data; |
| 547 | int ret = 0; |
| 548 | |
| 549 | if (!user) |
| 550 | return POLLERR|POLLNVAL; |
| 551 | |
| 552 | poll_wait(file, &log_wait, wait); |
| 553 | |
| 554 | raw_spin_lock(&logbuf_lock); |
| 555 | if (user->seq < log_next_seq) { |
| 556 | /* return error when data has vanished underneath us */ |
| 557 | if (user->seq < log_first_seq) |
| 558 | ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI; |
| 559 | ret = POLLIN|POLLRDNORM; |
| 560 | } |
| 561 | raw_spin_unlock(&logbuf_lock); |
| 562 | |
| 563 | return ret; |
| 564 | } |
| 565 | |
| 566 | static int devkmsg_open(struct inode *inode, struct file *file) |
| 567 | { |
| 568 | struct devkmsg_user *user; |
| 569 | int err; |
| 570 | |
| 571 | /* write-only does not need any file context */ |
| 572 | if ((file->f_flags & O_ACCMODE) == O_WRONLY) |
| 573 | return 0; |
| 574 | |
| 575 | err = security_syslog(SYSLOG_ACTION_READ_ALL); |
| 576 | if (err) |
| 577 | return err; |
| 578 | |
| 579 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); |
| 580 | if (!user) |
| 581 | return -ENOMEM; |
| 582 | |
| 583 | mutex_init(&user->lock); |
| 584 | |
| 585 | raw_spin_lock(&logbuf_lock); |
| 586 | user->idx = log_first_idx; |
| 587 | user->seq = log_first_seq; |
| 588 | raw_spin_unlock(&logbuf_lock); |
| 589 | |
| 590 | file->private_data = user; |
| 591 | return 0; |
| 592 | } |
| 593 | |
| 594 | static int devkmsg_release(struct inode *inode, struct file *file) |
| 595 | { |
| 596 | struct devkmsg_user *user = file->private_data; |
| 597 | |
| 598 | if (!user) |
| 599 | return 0; |
| 600 | |
| 601 | mutex_destroy(&user->lock); |
| 602 | kfree(user); |
| 603 | return 0; |
| 604 | } |
| 605 | |
| 606 | const struct file_operations kmsg_fops = { |
| 607 | .open = devkmsg_open, |
| 608 | .read = devkmsg_read, |
| 609 | .aio_write = devkmsg_writev, |
| 610 | .llseek = devkmsg_llseek, |
| 611 | .poll = devkmsg_poll, |
| 612 | .release = devkmsg_release, |
| 613 | }; |
| 614 | |
| 615 | #ifdef CONFIG_KEXEC |
| 616 | /* |
| 617 | * This appends the listed symbols to /proc/vmcoreinfo |
| 618 | * |
| 619 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to |
| 620 | * obtain access to symbols that are otherwise very difficult to locate. These |
| 621 | * symbols are specifically used so that utilities can access and extract the |
| 622 | * dmesg log from a vmcore file after a crash. |
| 623 | */ |
| 624 | void log_buf_kexec_setup(void) |
| 625 | { |
| 626 | VMCOREINFO_SYMBOL(log_buf); |
| 627 | VMCOREINFO_SYMBOL(log_buf_len); |
| 628 | VMCOREINFO_SYMBOL(log_first_idx); |
| 629 | VMCOREINFO_SYMBOL(log_next_idx); |
| 630 | } |
| 631 | #endif |
| 632 | |
| 633 | /* requested log_buf_len from kernel cmdline */ |
| 634 | static unsigned long __initdata new_log_buf_len; |
| 635 | |
| 636 | /* save requested log_buf_len since it's too early to process it */ |
| 637 | static int __init log_buf_len_setup(char *str) |
| 638 | { |
| 639 | unsigned size = memparse(str, &str); |
| 640 | |
| 641 | if (size) |
| 642 | size = roundup_pow_of_two(size); |
| 643 | if (size > log_buf_len) |
| 644 | new_log_buf_len = size; |
| 645 | |
| 646 | return 0; |
| 647 | } |
| 648 | early_param("log_buf_len", log_buf_len_setup); |
| 649 | |
| 650 | void __init setup_log_buf(int early) |
| 651 | { |
| 652 | unsigned long flags; |
| 653 | char *new_log_buf; |
| 654 | int free; |
| 655 | |
| 656 | if (!new_log_buf_len) |
| 657 | return; |
| 658 | |
| 659 | if (early) { |
| 660 | unsigned long mem; |
| 661 | |
| 662 | mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); |
| 663 | if (!mem) |
| 664 | return; |
| 665 | new_log_buf = __va(mem); |
| 666 | } else { |
| 667 | new_log_buf = alloc_bootmem_nopanic(new_log_buf_len); |
| 668 | } |
| 669 | |
| 670 | if (unlikely(!new_log_buf)) { |
| 671 | pr_err("log_buf_len: %ld bytes not available\n", |
| 672 | new_log_buf_len); |
| 673 | return; |
| 674 | } |
| 675 | |
| 676 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 677 | log_buf_len = new_log_buf_len; |
| 678 | log_buf = new_log_buf; |
| 679 | new_log_buf_len = 0; |
| 680 | free = __LOG_BUF_LEN - log_next_idx; |
| 681 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); |
| 682 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 683 | |
| 684 | pr_info("log_buf_len: %d\n", log_buf_len); |
| 685 | pr_info("early log buf free: %d(%d%%)\n", |
| 686 | free, (free * 100) / __LOG_BUF_LEN); |
| 687 | } |
| 688 | |
| 689 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
| 690 | |
| 691 | static int boot_delay; /* msecs delay after each printk during bootup */ |
| 692 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
| 693 | |
| 694 | static int __init boot_delay_setup(char *str) |
| 695 | { |
| 696 | unsigned long lpj; |
| 697 | |
| 698 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
| 699 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
| 700 | |
| 701 | get_option(&str, &boot_delay); |
| 702 | if (boot_delay > 10 * 1000) |
| 703 | boot_delay = 0; |
| 704 | |
| 705 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
| 706 | "HZ: %d, loops_per_msec: %llu\n", |
| 707 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
| 708 | return 1; |
| 709 | } |
| 710 | __setup("boot_delay=", boot_delay_setup); |
| 711 | |
| 712 | static void boot_delay_msec(void) |
| 713 | { |
| 714 | unsigned long long k; |
| 715 | unsigned long timeout; |
| 716 | |
| 717 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) |
| 718 | return; |
| 719 | |
| 720 | k = (unsigned long long)loops_per_msec * boot_delay; |
| 721 | |
| 722 | timeout = jiffies + msecs_to_jiffies(boot_delay); |
| 723 | while (k) { |
| 724 | k--; |
| 725 | cpu_relax(); |
| 726 | /* |
| 727 | * use (volatile) jiffies to prevent |
| 728 | * compiler reduction; loop termination via jiffies |
| 729 | * is secondary and may or may not happen. |
| 730 | */ |
| 731 | if (time_after(jiffies, timeout)) |
| 732 | break; |
| 733 | touch_nmi_watchdog(); |
| 734 | } |
| 735 | } |
| 736 | #else |
| 737 | static inline void boot_delay_msec(void) |
| 738 | { |
| 739 | } |
| 740 | #endif |
| 741 | |
| 742 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
| 743 | int dmesg_restrict = 1; |
| 744 | #else |
| 745 | int dmesg_restrict; |
| 746 | #endif |
| 747 | |
| 748 | static int syslog_action_restricted(int type) |
| 749 | { |
| 750 | if (dmesg_restrict) |
| 751 | return 1; |
| 752 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ |
| 753 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; |
| 754 | } |
| 755 | |
| 756 | static int check_syslog_permissions(int type, bool from_file) |
| 757 | { |
| 758 | /* |
| 759 | * If this is from /proc/kmsg and we've already opened it, then we've |
| 760 | * already done the capabilities checks at open time. |
| 761 | */ |
| 762 | if (from_file && type != SYSLOG_ACTION_OPEN) |
| 763 | return 0; |
| 764 | |
| 765 | if (syslog_action_restricted(type)) { |
| 766 | if (capable(CAP_SYSLOG)) |
| 767 | return 0; |
| 768 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ |
| 769 | if (capable(CAP_SYS_ADMIN)) { |
| 770 | printk_once(KERN_WARNING "%s (%d): " |
| 771 | "Attempt to access syslog with CAP_SYS_ADMIN " |
| 772 | "but no CAP_SYSLOG (deprecated).\n", |
| 773 | current->comm, task_pid_nr(current)); |
| 774 | return 0; |
| 775 | } |
| 776 | return -EPERM; |
| 777 | } |
| 778 | return 0; |
| 779 | } |
| 780 | |
| 781 | #if defined(CONFIG_PRINTK_TIME) |
| 782 | static bool printk_time = 1; |
| 783 | #else |
| 784 | static bool printk_time; |
| 785 | #endif |
| 786 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
| 787 | |
| 788 | static size_t print_prefix(const struct log *msg, bool syslog, char *buf) |
| 789 | { |
| 790 | size_t len = 0; |
| 791 | |
| 792 | if (syslog) { |
| 793 | if (buf) { |
| 794 | len += sprintf(buf, "<%u>", msg->level); |
| 795 | } else { |
| 796 | len += 3; |
| 797 | if (msg->level > 9) |
| 798 | len++; |
| 799 | if (msg->level > 99) |
| 800 | len++; |
| 801 | } |
| 802 | } |
| 803 | |
| 804 | if (printk_time) { |
| 805 | if (buf) { |
| 806 | unsigned long long ts = msg->ts_nsec; |
| 807 | unsigned long rem_nsec = do_div(ts, 1000000000); |
| 808 | |
| 809 | len += sprintf(buf + len, "[%5lu.%06lu] ", |
| 810 | (unsigned long) ts, rem_nsec / 1000); |
| 811 | } else { |
| 812 | len += 15; |
| 813 | } |
| 814 | } |
| 815 | |
| 816 | return len; |
| 817 | } |
| 818 | |
| 819 | static size_t msg_print_text(const struct log *msg, bool syslog, |
| 820 | char *buf, size_t size) |
| 821 | { |
| 822 | const char *text = log_text(msg); |
| 823 | size_t text_size = msg->text_len; |
| 824 | size_t len = 0; |
| 825 | |
| 826 | do { |
| 827 | const char *next = memchr(text, '\n', text_size); |
| 828 | size_t text_len; |
| 829 | |
| 830 | if (next) { |
| 831 | text_len = next - text; |
| 832 | next++; |
| 833 | text_size -= next - text; |
| 834 | } else { |
| 835 | text_len = text_size; |
| 836 | } |
| 837 | |
| 838 | if (buf) { |
| 839 | if (print_prefix(msg, syslog, NULL) + |
| 840 | text_len + 1>= size - len) |
| 841 | break; |
| 842 | |
| 843 | len += print_prefix(msg, syslog, buf + len); |
| 844 | memcpy(buf + len, text, text_len); |
| 845 | len += text_len; |
| 846 | buf[len++] = '\n'; |
| 847 | } else { |
| 848 | /* SYSLOG_ACTION_* buffer size only calculation */ |
| 849 | len += print_prefix(msg, syslog, NULL); |
| 850 | len += text_len + 1; |
| 851 | } |
| 852 | |
| 853 | text = next; |
| 854 | } while (text); |
| 855 | |
| 856 | return len; |
| 857 | } |
| 858 | |
| 859 | static int syslog_print(char __user *buf, int size) |
| 860 | { |
| 861 | char *text; |
| 862 | struct log *msg; |
| 863 | int len; |
| 864 | |
| 865 | text = kmalloc(LOG_LINE_MAX, GFP_KERNEL); |
| 866 | if (!text) |
| 867 | return -ENOMEM; |
| 868 | |
| 869 | raw_spin_lock_irq(&logbuf_lock); |
| 870 | if (syslog_seq < log_first_seq) { |
| 871 | /* messages are gone, move to first one */ |
| 872 | syslog_seq = log_first_seq; |
| 873 | syslog_idx = log_first_idx; |
| 874 | } |
| 875 | msg = log_from_idx(syslog_idx); |
| 876 | len = msg_print_text(msg, true, text, LOG_LINE_MAX); |
| 877 | syslog_idx = log_next(syslog_idx); |
| 878 | syslog_seq++; |
| 879 | raw_spin_unlock_irq(&logbuf_lock); |
| 880 | |
| 881 | if (len > 0 && copy_to_user(buf, text, len)) |
| 882 | len = -EFAULT; |
| 883 | |
| 884 | kfree(text); |
| 885 | return len; |
| 886 | } |
| 887 | |
| 888 | static int syslog_print_all(char __user *buf, int size, bool clear) |
| 889 | { |
| 890 | char *text; |
| 891 | int len = 0; |
| 892 | |
| 893 | text = kmalloc(LOG_LINE_MAX, GFP_KERNEL); |
| 894 | if (!text) |
| 895 | return -ENOMEM; |
| 896 | |
| 897 | raw_spin_lock_irq(&logbuf_lock); |
| 898 | if (buf) { |
| 899 | u64 next_seq; |
| 900 | u64 seq; |
| 901 | u32 idx; |
| 902 | |
| 903 | if (clear_seq < log_first_seq) { |
| 904 | /* messages are gone, move to first available one */ |
| 905 | clear_seq = log_first_seq; |
| 906 | clear_idx = log_first_idx; |
| 907 | } |
| 908 | |
| 909 | /* |
| 910 | * Find first record that fits, including all following records, |
| 911 | * into the user-provided buffer for this dump. |
| 912 | */ |
| 913 | seq = clear_seq; |
| 914 | idx = clear_idx; |
| 915 | while (seq < log_next_seq) { |
| 916 | struct log *msg = log_from_idx(idx); |
| 917 | |
| 918 | len += msg_print_text(msg, true, NULL, 0); |
| 919 | idx = log_next(idx); |
| 920 | seq++; |
| 921 | } |
| 922 | seq = clear_seq; |
| 923 | idx = clear_idx; |
| 924 | while (len > size && seq < log_next_seq) { |
| 925 | struct log *msg = log_from_idx(idx); |
| 926 | |
| 927 | len -= msg_print_text(msg, true, NULL, 0); |
| 928 | idx = log_next(idx); |
| 929 | seq++; |
| 930 | } |
| 931 | |
| 932 | /* last message in this dump */ |
| 933 | next_seq = log_next_seq; |
| 934 | |
| 935 | len = 0; |
| 936 | while (len >= 0 && seq < next_seq) { |
| 937 | struct log *msg = log_from_idx(idx); |
| 938 | int textlen; |
| 939 | |
| 940 | textlen = msg_print_text(msg, true, text, LOG_LINE_MAX); |
| 941 | if (textlen < 0) { |
| 942 | len = textlen; |
| 943 | break; |
| 944 | } |
| 945 | idx = log_next(idx); |
| 946 | seq++; |
| 947 | |
| 948 | raw_spin_unlock_irq(&logbuf_lock); |
| 949 | if (copy_to_user(buf + len, text, textlen)) |
| 950 | len = -EFAULT; |
| 951 | else |
| 952 | len += textlen; |
| 953 | raw_spin_lock_irq(&logbuf_lock); |
| 954 | |
| 955 | if (seq < log_first_seq) { |
| 956 | /* messages are gone, move to next one */ |
| 957 | seq = log_first_seq; |
| 958 | idx = log_first_idx; |
| 959 | } |
| 960 | } |
| 961 | } |
| 962 | |
| 963 | if (clear) { |
| 964 | clear_seq = log_next_seq; |
| 965 | clear_idx = log_next_idx; |
| 966 | } |
| 967 | raw_spin_unlock_irq(&logbuf_lock); |
| 968 | |
| 969 | kfree(text); |
| 970 | return len; |
| 971 | } |
| 972 | |
| 973 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
| 974 | { |
| 975 | bool clear = false; |
| 976 | static int saved_console_loglevel = -1; |
| 977 | int error; |
| 978 | |
| 979 | error = check_syslog_permissions(type, from_file); |
| 980 | if (error) |
| 981 | goto out; |
| 982 | |
| 983 | error = security_syslog(type); |
| 984 | if (error) |
| 985 | return error; |
| 986 | |
| 987 | switch (type) { |
| 988 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
| 989 | break; |
| 990 | case SYSLOG_ACTION_OPEN: /* Open log */ |
| 991 | break; |
| 992 | case SYSLOG_ACTION_READ: /* Read from log */ |
| 993 | error = -EINVAL; |
| 994 | if (!buf || len < 0) |
| 995 | goto out; |
| 996 | error = 0; |
| 997 | if (!len) |
| 998 | goto out; |
| 999 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
| 1000 | error = -EFAULT; |
| 1001 | goto out; |
| 1002 | } |
| 1003 | error = wait_event_interruptible(log_wait, |
| 1004 | syslog_seq != log_next_seq); |
| 1005 | if (error) |
| 1006 | goto out; |
| 1007 | error = syslog_print(buf, len); |
| 1008 | break; |
| 1009 | /* Read/clear last kernel messages */ |
| 1010 | case SYSLOG_ACTION_READ_CLEAR: |
| 1011 | clear = true; |
| 1012 | /* FALL THRU */ |
| 1013 | /* Read last kernel messages */ |
| 1014 | case SYSLOG_ACTION_READ_ALL: |
| 1015 | error = -EINVAL; |
| 1016 | if (!buf || len < 0) |
| 1017 | goto out; |
| 1018 | error = 0; |
| 1019 | if (!len) |
| 1020 | goto out; |
| 1021 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
| 1022 | error = -EFAULT; |
| 1023 | goto out; |
| 1024 | } |
| 1025 | error = syslog_print_all(buf, len, clear); |
| 1026 | break; |
| 1027 | /* Clear ring buffer */ |
| 1028 | case SYSLOG_ACTION_CLEAR: |
| 1029 | syslog_print_all(NULL, 0, true); |
| 1030 | /* Disable logging to console */ |
| 1031 | case SYSLOG_ACTION_CONSOLE_OFF: |
| 1032 | if (saved_console_loglevel == -1) |
| 1033 | saved_console_loglevel = console_loglevel; |
| 1034 | console_loglevel = minimum_console_loglevel; |
| 1035 | break; |
| 1036 | /* Enable logging to console */ |
| 1037 | case SYSLOG_ACTION_CONSOLE_ON: |
| 1038 | if (saved_console_loglevel != -1) { |
| 1039 | console_loglevel = saved_console_loglevel; |
| 1040 | saved_console_loglevel = -1; |
| 1041 | } |
| 1042 | break; |
| 1043 | /* Set level of messages printed to console */ |
| 1044 | case SYSLOG_ACTION_CONSOLE_LEVEL: |
| 1045 | error = -EINVAL; |
| 1046 | if (len < 1 || len > 8) |
| 1047 | goto out; |
| 1048 | if (len < minimum_console_loglevel) |
| 1049 | len = minimum_console_loglevel; |
| 1050 | console_loglevel = len; |
| 1051 | /* Implicitly re-enable logging to console */ |
| 1052 | saved_console_loglevel = -1; |
| 1053 | error = 0; |
| 1054 | break; |
| 1055 | /* Number of chars in the log buffer */ |
| 1056 | case SYSLOG_ACTION_SIZE_UNREAD: |
| 1057 | raw_spin_lock_irq(&logbuf_lock); |
| 1058 | if (syslog_seq < log_first_seq) { |
| 1059 | /* messages are gone, move to first one */ |
| 1060 | syslog_seq = log_first_seq; |
| 1061 | syslog_idx = log_first_idx; |
| 1062 | } |
| 1063 | if (from_file) { |
| 1064 | /* |
| 1065 | * Short-cut for poll(/"proc/kmsg") which simply checks |
| 1066 | * for pending data, not the size; return the count of |
| 1067 | * records, not the length. |
| 1068 | */ |
| 1069 | error = log_next_idx - syslog_idx; |
| 1070 | } else { |
| 1071 | u64 seq; |
| 1072 | u32 idx; |
| 1073 | |
| 1074 | error = 0; |
| 1075 | seq = syslog_seq; |
| 1076 | idx = syslog_idx; |
| 1077 | while (seq < log_next_seq) { |
| 1078 | struct log *msg = log_from_idx(idx); |
| 1079 | |
| 1080 | error += msg_print_text(msg, true, NULL, 0); |
| 1081 | idx = log_next(idx); |
| 1082 | seq++; |
| 1083 | } |
| 1084 | } |
| 1085 | raw_spin_unlock_irq(&logbuf_lock); |
| 1086 | break; |
| 1087 | /* Size of the log buffer */ |
| 1088 | case SYSLOG_ACTION_SIZE_BUFFER: |
| 1089 | error = log_buf_len; |
| 1090 | break; |
| 1091 | default: |
| 1092 | error = -EINVAL; |
| 1093 | break; |
| 1094 | } |
| 1095 | out: |
| 1096 | return error; |
| 1097 | } |
| 1098 | |
| 1099 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
| 1100 | { |
| 1101 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
| 1102 | } |
| 1103 | |
| 1104 | #ifdef CONFIG_KGDB_KDB |
| 1105 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() |
| 1106 | * uses locks so it cannot be used during debugging. Just tell kdb |
| 1107 | * where the start and end of the physical and logical logs are. This |
| 1108 | * is equivalent to do_syslog(3). |
| 1109 | */ |
| 1110 | void kdb_syslog_data(char *syslog_data[4]) |
| 1111 | { |
| 1112 | syslog_data[0] = log_buf; |
| 1113 | syslog_data[1] = log_buf + log_buf_len; |
| 1114 | syslog_data[2] = log_buf + log_first_idx; |
| 1115 | syslog_data[3] = log_buf + log_next_idx; |
| 1116 | } |
| 1117 | #endif /* CONFIG_KGDB_KDB */ |
| 1118 | |
| 1119 | static bool __read_mostly ignore_loglevel; |
| 1120 | |
| 1121 | static int __init ignore_loglevel_setup(char *str) |
| 1122 | { |
| 1123 | ignore_loglevel = 1; |
| 1124 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); |
| 1125 | |
| 1126 | return 0; |
| 1127 | } |
| 1128 | |
| 1129 | early_param("ignore_loglevel", ignore_loglevel_setup); |
| 1130 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
| 1131 | MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" |
| 1132 | "print all kernel messages to the console."); |
| 1133 | |
| 1134 | /* |
| 1135 | * Call the console drivers, asking them to write out |
| 1136 | * log_buf[start] to log_buf[end - 1]. |
| 1137 | * The console_lock must be held. |
| 1138 | */ |
| 1139 | static void call_console_drivers(int level, const char *text, size_t len) |
| 1140 | { |
| 1141 | struct console *con; |
| 1142 | |
| 1143 | trace_console(text, 0, len, len); |
| 1144 | |
| 1145 | if (level >= console_loglevel && !ignore_loglevel) |
| 1146 | return; |
| 1147 | if (!console_drivers) |
| 1148 | return; |
| 1149 | |
| 1150 | for_each_console(con) { |
| 1151 | if (exclusive_console && con != exclusive_console) |
| 1152 | continue; |
| 1153 | if (!(con->flags & CON_ENABLED)) |
| 1154 | continue; |
| 1155 | if (!con->write) |
| 1156 | continue; |
| 1157 | if (!cpu_online(smp_processor_id()) && |
| 1158 | !(con->flags & CON_ANYTIME)) |
| 1159 | continue; |
| 1160 | con->write(con, text, len); |
| 1161 | } |
| 1162 | } |
| 1163 | |
| 1164 | /* |
| 1165 | * Zap console related locks when oopsing. Only zap at most once |
| 1166 | * every 10 seconds, to leave time for slow consoles to print a |
| 1167 | * full oops. |
| 1168 | */ |
| 1169 | static void zap_locks(void) |
| 1170 | { |
| 1171 | static unsigned long oops_timestamp; |
| 1172 | |
| 1173 | if (time_after_eq(jiffies, oops_timestamp) && |
| 1174 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
| 1175 | return; |
| 1176 | |
| 1177 | oops_timestamp = jiffies; |
| 1178 | |
| 1179 | debug_locks_off(); |
| 1180 | /* If a crash is occurring, make sure we can't deadlock */ |
| 1181 | raw_spin_lock_init(&logbuf_lock); |
| 1182 | /* And make sure that we print immediately */ |
| 1183 | sema_init(&console_sem, 1); |
| 1184 | } |
| 1185 | |
| 1186 | /* Check if we have any console registered that can be called early in boot. */ |
| 1187 | static int have_callable_console(void) |
| 1188 | { |
| 1189 | struct console *con; |
| 1190 | |
| 1191 | for_each_console(con) |
| 1192 | if (con->flags & CON_ANYTIME) |
| 1193 | return 1; |
| 1194 | |
| 1195 | return 0; |
| 1196 | } |
| 1197 | |
| 1198 | /* |
| 1199 | * Can we actually use the console at this time on this cpu? |
| 1200 | * |
| 1201 | * Console drivers may assume that per-cpu resources have |
| 1202 | * been allocated. So unless they're explicitly marked as |
| 1203 | * being able to cope (CON_ANYTIME) don't call them until |
| 1204 | * this CPU is officially up. |
| 1205 | */ |
| 1206 | static inline int can_use_console(unsigned int cpu) |
| 1207 | { |
| 1208 | return cpu_online(cpu) || have_callable_console(); |
| 1209 | } |
| 1210 | |
| 1211 | /* |
| 1212 | * Try to get console ownership to actually show the kernel |
| 1213 | * messages from a 'printk'. Return true (and with the |
| 1214 | * console_lock held, and 'console_locked' set) if it |
| 1215 | * is successful, false otherwise. |
| 1216 | * |
| 1217 | * This gets called with the 'logbuf_lock' spinlock held and |
| 1218 | * interrupts disabled. It should return with 'lockbuf_lock' |
| 1219 | * released but interrupts still disabled. |
| 1220 | */ |
| 1221 | static int console_trylock_for_printk(unsigned int cpu) |
| 1222 | __releases(&logbuf_lock) |
| 1223 | { |
| 1224 | int retval = 0, wake = 0; |
| 1225 | |
| 1226 | if (console_trylock()) { |
| 1227 | retval = 1; |
| 1228 | |
| 1229 | /* |
| 1230 | * If we can't use the console, we need to release |
| 1231 | * the console semaphore by hand to avoid flushing |
| 1232 | * the buffer. We need to hold the console semaphore |
| 1233 | * in order to do this test safely. |
| 1234 | */ |
| 1235 | if (!can_use_console(cpu)) { |
| 1236 | console_locked = 0; |
| 1237 | wake = 1; |
| 1238 | retval = 0; |
| 1239 | } |
| 1240 | } |
| 1241 | logbuf_cpu = UINT_MAX; |
| 1242 | if (wake) |
| 1243 | up(&console_sem); |
| 1244 | raw_spin_unlock(&logbuf_lock); |
| 1245 | return retval; |
| 1246 | } |
| 1247 | |
| 1248 | int printk_delay_msec __read_mostly; |
| 1249 | |
| 1250 | static inline void printk_delay(void) |
| 1251 | { |
| 1252 | if (unlikely(printk_delay_msec)) { |
| 1253 | int m = printk_delay_msec; |
| 1254 | |
| 1255 | while (m--) { |
| 1256 | mdelay(1); |
| 1257 | touch_nmi_watchdog(); |
| 1258 | } |
| 1259 | } |
| 1260 | } |
| 1261 | |
| 1262 | asmlinkage int vprintk_emit(int facility, int level, |
| 1263 | const char *dict, size_t dictlen, |
| 1264 | const char *fmt, va_list args) |
| 1265 | { |
| 1266 | static int recursion_bug; |
| 1267 | static char cont_buf[LOG_LINE_MAX]; |
| 1268 | static size_t cont_len; |
| 1269 | static int cont_level; |
| 1270 | static struct task_struct *cont_task; |
| 1271 | static char textbuf[LOG_LINE_MAX]; |
| 1272 | char *text = textbuf; |
| 1273 | size_t text_len; |
| 1274 | unsigned long flags; |
| 1275 | int this_cpu; |
| 1276 | bool newline = false; |
| 1277 | bool prefix = false; |
| 1278 | int printed_len = 0; |
| 1279 | |
| 1280 | boot_delay_msec(); |
| 1281 | printk_delay(); |
| 1282 | |
| 1283 | /* This stops the holder of console_sem just where we want him */ |
| 1284 | local_irq_save(flags); |
| 1285 | this_cpu = smp_processor_id(); |
| 1286 | |
| 1287 | /* |
| 1288 | * Ouch, printk recursed into itself! |
| 1289 | */ |
| 1290 | if (unlikely(logbuf_cpu == this_cpu)) { |
| 1291 | /* |
| 1292 | * If a crash is occurring during printk() on this CPU, |
| 1293 | * then try to get the crash message out but make sure |
| 1294 | * we can't deadlock. Otherwise just return to avoid the |
| 1295 | * recursion and return - but flag the recursion so that |
| 1296 | * it can be printed at the next appropriate moment: |
| 1297 | */ |
| 1298 | if (!oops_in_progress && !lockdep_recursing(current)) { |
| 1299 | recursion_bug = 1; |
| 1300 | goto out_restore_irqs; |
| 1301 | } |
| 1302 | zap_locks(); |
| 1303 | } |
| 1304 | |
| 1305 | lockdep_off(); |
| 1306 | raw_spin_lock(&logbuf_lock); |
| 1307 | logbuf_cpu = this_cpu; |
| 1308 | |
| 1309 | if (recursion_bug) { |
| 1310 | static const char recursion_msg[] = |
| 1311 | "BUG: recent printk recursion!"; |
| 1312 | |
| 1313 | recursion_bug = 0; |
| 1314 | printed_len += strlen(recursion_msg); |
| 1315 | /* emit KERN_CRIT message */ |
| 1316 | log_store(0, 2, NULL, 0, recursion_msg, printed_len); |
| 1317 | } |
| 1318 | |
| 1319 | /* |
| 1320 | * The printf needs to come first; we need the syslog |
| 1321 | * prefix which might be passed-in as a parameter. |
| 1322 | */ |
| 1323 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
| 1324 | |
| 1325 | /* mark and strip a trailing newline */ |
| 1326 | if (text_len && text[text_len-1] == '\n') { |
| 1327 | text_len--; |
| 1328 | newline = true; |
| 1329 | } |
| 1330 | |
| 1331 | /* strip syslog prefix and extract log level or control flags */ |
| 1332 | if (text[0] == '<' && text[1] && text[2] == '>') { |
| 1333 | switch (text[1]) { |
| 1334 | case '0' ... '7': |
| 1335 | if (level == -1) |
| 1336 | level = text[1] - '0'; |
| 1337 | case 'd': /* KERN_DEFAULT */ |
| 1338 | prefix = true; |
| 1339 | case 'c': /* KERN_CONT */ |
| 1340 | text += 3; |
| 1341 | text_len -= 3; |
| 1342 | } |
| 1343 | } |
| 1344 | |
| 1345 | if (level == -1) |
| 1346 | level = default_message_loglevel; |
| 1347 | |
| 1348 | if (dict) { |
| 1349 | prefix = true; |
| 1350 | newline = true; |
| 1351 | } |
| 1352 | |
| 1353 | if (!newline) { |
| 1354 | if (cont_len && (prefix || cont_task != current)) { |
| 1355 | /* |
| 1356 | * Flush earlier buffer, which is either from a |
| 1357 | * different thread, or when we got a new prefix. |
| 1358 | */ |
| 1359 | log_store(facility, cont_level, NULL, 0, cont_buf, cont_len); |
| 1360 | cont_len = 0; |
| 1361 | } |
| 1362 | |
| 1363 | if (!cont_len) { |
| 1364 | cont_level = level; |
| 1365 | cont_task = current; |
| 1366 | } |
| 1367 | |
| 1368 | /* buffer or append to earlier buffer from the same thread */ |
| 1369 | if (cont_len + text_len > sizeof(cont_buf)) |
| 1370 | text_len = sizeof(cont_buf) - cont_len; |
| 1371 | memcpy(cont_buf + cont_len, text, text_len); |
| 1372 | cont_len += text_len; |
| 1373 | } else { |
| 1374 | if (cont_len && cont_task == current) { |
| 1375 | if (prefix) { |
| 1376 | /* |
| 1377 | * New prefix from the same thread; flush. We |
| 1378 | * either got no earlier newline, or we race |
| 1379 | * with an interrupt. |
| 1380 | */ |
| 1381 | log_store(facility, cont_level, |
| 1382 | NULL, 0, cont_buf, cont_len); |
| 1383 | cont_len = 0; |
| 1384 | } |
| 1385 | |
| 1386 | /* append to the earlier buffer and flush */ |
| 1387 | if (cont_len + text_len > sizeof(cont_buf)) |
| 1388 | text_len = sizeof(cont_buf) - cont_len; |
| 1389 | memcpy(cont_buf + cont_len, text, text_len); |
| 1390 | cont_len += text_len; |
| 1391 | log_store(facility, cont_level, |
| 1392 | NULL, 0, cont_buf, cont_len); |
| 1393 | cont_len = 0; |
| 1394 | cont_task = NULL; |
| 1395 | printed_len = cont_len; |
| 1396 | } else { |
| 1397 | /* ordinary single and terminated line */ |
| 1398 | log_store(facility, level, |
| 1399 | dict, dictlen, text, text_len); |
| 1400 | printed_len = text_len; |
| 1401 | } |
| 1402 | } |
| 1403 | |
| 1404 | /* |
| 1405 | * Try to acquire and then immediately release the console semaphore. |
| 1406 | * The release will print out buffers and wake up /dev/kmsg and syslog() |
| 1407 | * users. |
| 1408 | * |
| 1409 | * The console_trylock_for_printk() function will release 'logbuf_lock' |
| 1410 | * regardless of whether it actually gets the console semaphore or not. |
| 1411 | */ |
| 1412 | if (console_trylock_for_printk(this_cpu)) |
| 1413 | console_unlock(); |
| 1414 | |
| 1415 | lockdep_on(); |
| 1416 | out_restore_irqs: |
| 1417 | local_irq_restore(flags); |
| 1418 | |
| 1419 | return printed_len; |
| 1420 | } |
| 1421 | EXPORT_SYMBOL(vprintk_emit); |
| 1422 | |
| 1423 | asmlinkage int vprintk(const char *fmt, va_list args) |
| 1424 | { |
| 1425 | return vprintk_emit(0, -1, NULL, 0, fmt, args); |
| 1426 | } |
| 1427 | EXPORT_SYMBOL(vprintk); |
| 1428 | |
| 1429 | asmlinkage int printk_emit(int facility, int level, |
| 1430 | const char *dict, size_t dictlen, |
| 1431 | const char *fmt, ...) |
| 1432 | { |
| 1433 | va_list args; |
| 1434 | int r; |
| 1435 | |
| 1436 | va_start(args, fmt); |
| 1437 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); |
| 1438 | va_end(args); |
| 1439 | |
| 1440 | return r; |
| 1441 | } |
| 1442 | EXPORT_SYMBOL(printk_emit); |
| 1443 | |
| 1444 | /** |
| 1445 | * printk - print a kernel message |
| 1446 | * @fmt: format string |
| 1447 | * |
| 1448 | * This is printk(). It can be called from any context. We want it to work. |
| 1449 | * |
| 1450 | * We try to grab the console_lock. If we succeed, it's easy - we log the |
| 1451 | * output and call the console drivers. If we fail to get the semaphore, we |
| 1452 | * place the output into the log buffer and return. The current holder of |
| 1453 | * the console_sem will notice the new output in console_unlock(); and will |
| 1454 | * send it to the consoles before releasing the lock. |
| 1455 | * |
| 1456 | * One effect of this deferred printing is that code which calls printk() and |
| 1457 | * then changes console_loglevel may break. This is because console_loglevel |
| 1458 | * is inspected when the actual printing occurs. |
| 1459 | * |
| 1460 | * See also: |
| 1461 | * printf(3) |
| 1462 | * |
| 1463 | * See the vsnprintf() documentation for format string extensions over C99. |
| 1464 | */ |
| 1465 | asmlinkage int printk(const char *fmt, ...) |
| 1466 | { |
| 1467 | va_list args; |
| 1468 | int r; |
| 1469 | |
| 1470 | #ifdef CONFIG_KGDB_KDB |
| 1471 | if (unlikely(kdb_trap_printk)) { |
| 1472 | va_start(args, fmt); |
| 1473 | r = vkdb_printf(fmt, args); |
| 1474 | va_end(args); |
| 1475 | return r; |
| 1476 | } |
| 1477 | #endif |
| 1478 | va_start(args, fmt); |
| 1479 | r = vprintk_emit(0, -1, NULL, 0, fmt, args); |
| 1480 | va_end(args); |
| 1481 | |
| 1482 | return r; |
| 1483 | } |
| 1484 | EXPORT_SYMBOL(printk); |
| 1485 | |
| 1486 | #else |
| 1487 | |
| 1488 | #define LOG_LINE_MAX 0 |
| 1489 | static struct log *log_from_idx(u32 idx) { return NULL; } |
| 1490 | static u32 log_next(u32 idx) { return 0; } |
| 1491 | static void call_console_drivers(int level, const char *text, size_t len) {} |
| 1492 | static size_t msg_print_text(const struct log *msg, bool syslog, |
| 1493 | char *buf, size_t size) { return 0; } |
| 1494 | |
| 1495 | #endif /* CONFIG_PRINTK */ |
| 1496 | |
| 1497 | static int __add_preferred_console(char *name, int idx, char *options, |
| 1498 | char *brl_options) |
| 1499 | { |
| 1500 | struct console_cmdline *c; |
| 1501 | int i; |
| 1502 | |
| 1503 | /* |
| 1504 | * See if this tty is not yet registered, and |
| 1505 | * if we have a slot free. |
| 1506 | */ |
| 1507 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
| 1508 | if (strcmp(console_cmdline[i].name, name) == 0 && |
| 1509 | console_cmdline[i].index == idx) { |
| 1510 | if (!brl_options) |
| 1511 | selected_console = i; |
| 1512 | return 0; |
| 1513 | } |
| 1514 | if (i == MAX_CMDLINECONSOLES) |
| 1515 | return -E2BIG; |
| 1516 | if (!brl_options) |
| 1517 | selected_console = i; |
| 1518 | c = &console_cmdline[i]; |
| 1519 | strlcpy(c->name, name, sizeof(c->name)); |
| 1520 | c->options = options; |
| 1521 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| 1522 | c->brl_options = brl_options; |
| 1523 | #endif |
| 1524 | c->index = idx; |
| 1525 | return 0; |
| 1526 | } |
| 1527 | /* |
| 1528 | * Set up a list of consoles. Called from init/main.c |
| 1529 | */ |
| 1530 | static int __init console_setup(char *str) |
| 1531 | { |
| 1532 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
| 1533 | char *s, *options, *brl_options = NULL; |
| 1534 | int idx; |
| 1535 | |
| 1536 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| 1537 | if (!memcmp(str, "brl,", 4)) { |
| 1538 | brl_options = ""; |
| 1539 | str += 4; |
| 1540 | } else if (!memcmp(str, "brl=", 4)) { |
| 1541 | brl_options = str + 4; |
| 1542 | str = strchr(brl_options, ','); |
| 1543 | if (!str) { |
| 1544 | printk(KERN_ERR "need port name after brl=\n"); |
| 1545 | return 1; |
| 1546 | } |
| 1547 | *(str++) = 0; |
| 1548 | } |
| 1549 | #endif |
| 1550 | |
| 1551 | /* |
| 1552 | * Decode str into name, index, options. |
| 1553 | */ |
| 1554 | if (str[0] >= '0' && str[0] <= '9') { |
| 1555 | strcpy(buf, "ttyS"); |
| 1556 | strncpy(buf + 4, str, sizeof(buf) - 5); |
| 1557 | } else { |
| 1558 | strncpy(buf, str, sizeof(buf) - 1); |
| 1559 | } |
| 1560 | buf[sizeof(buf) - 1] = 0; |
| 1561 | if ((options = strchr(str, ',')) != NULL) |
| 1562 | *(options++) = 0; |
| 1563 | #ifdef __sparc__ |
| 1564 | if (!strcmp(str, "ttya")) |
| 1565 | strcpy(buf, "ttyS0"); |
| 1566 | if (!strcmp(str, "ttyb")) |
| 1567 | strcpy(buf, "ttyS1"); |
| 1568 | #endif |
| 1569 | for (s = buf; *s; s++) |
| 1570 | if ((*s >= '0' && *s <= '9') || *s == ',') |
| 1571 | break; |
| 1572 | idx = simple_strtoul(s, NULL, 10); |
| 1573 | *s = 0; |
| 1574 | |
| 1575 | __add_preferred_console(buf, idx, options, brl_options); |
| 1576 | console_set_on_cmdline = 1; |
| 1577 | return 1; |
| 1578 | } |
| 1579 | __setup("console=", console_setup); |
| 1580 | |
| 1581 | /** |
| 1582 | * add_preferred_console - add a device to the list of preferred consoles. |
| 1583 | * @name: device name |
| 1584 | * @idx: device index |
| 1585 | * @options: options for this console |
| 1586 | * |
| 1587 | * The last preferred console added will be used for kernel messages |
| 1588 | * and stdin/out/err for init. Normally this is used by console_setup |
| 1589 | * above to handle user-supplied console arguments; however it can also |
| 1590 | * be used by arch-specific code either to override the user or more |
| 1591 | * commonly to provide a default console (ie from PROM variables) when |
| 1592 | * the user has not supplied one. |
| 1593 | */ |
| 1594 | int add_preferred_console(char *name, int idx, char *options) |
| 1595 | { |
| 1596 | return __add_preferred_console(name, idx, options, NULL); |
| 1597 | } |
| 1598 | |
| 1599 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
| 1600 | { |
| 1601 | struct console_cmdline *c; |
| 1602 | int i; |
| 1603 | |
| 1604 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
| 1605 | if (strcmp(console_cmdline[i].name, name) == 0 && |
| 1606 | console_cmdline[i].index == idx) { |
| 1607 | c = &console_cmdline[i]; |
| 1608 | strlcpy(c->name, name_new, sizeof(c->name)); |
| 1609 | c->name[sizeof(c->name) - 1] = 0; |
| 1610 | c->options = options; |
| 1611 | c->index = idx_new; |
| 1612 | return i; |
| 1613 | } |
| 1614 | /* not found */ |
| 1615 | return -1; |
| 1616 | } |
| 1617 | |
| 1618 | bool console_suspend_enabled = 1; |
| 1619 | EXPORT_SYMBOL(console_suspend_enabled); |
| 1620 | |
| 1621 | static int __init console_suspend_disable(char *str) |
| 1622 | { |
| 1623 | console_suspend_enabled = 0; |
| 1624 | return 1; |
| 1625 | } |
| 1626 | __setup("no_console_suspend", console_suspend_disable); |
| 1627 | module_param_named(console_suspend, console_suspend_enabled, |
| 1628 | bool, S_IRUGO | S_IWUSR); |
| 1629 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" |
| 1630 | " and hibernate operations"); |
| 1631 | |
| 1632 | /** |
| 1633 | * suspend_console - suspend the console subsystem |
| 1634 | * |
| 1635 | * This disables printk() while we go into suspend states |
| 1636 | */ |
| 1637 | void suspend_console(void) |
| 1638 | { |
| 1639 | if (!console_suspend_enabled) |
| 1640 | return; |
| 1641 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
| 1642 | console_lock(); |
| 1643 | console_suspended = 1; |
| 1644 | up(&console_sem); |
| 1645 | } |
| 1646 | |
| 1647 | void resume_console(void) |
| 1648 | { |
| 1649 | if (!console_suspend_enabled) |
| 1650 | return; |
| 1651 | down(&console_sem); |
| 1652 | console_suspended = 0; |
| 1653 | console_unlock(); |
| 1654 | } |
| 1655 | |
| 1656 | /** |
| 1657 | * console_cpu_notify - print deferred console messages after CPU hotplug |
| 1658 | * @self: notifier struct |
| 1659 | * @action: CPU hotplug event |
| 1660 | * @hcpu: unused |
| 1661 | * |
| 1662 | * If printk() is called from a CPU that is not online yet, the messages |
| 1663 | * will be spooled but will not show up on the console. This function is |
| 1664 | * called when a new CPU comes online (or fails to come up), and ensures |
| 1665 | * that any such output gets printed. |
| 1666 | */ |
| 1667 | static int __cpuinit console_cpu_notify(struct notifier_block *self, |
| 1668 | unsigned long action, void *hcpu) |
| 1669 | { |
| 1670 | switch (action) { |
| 1671 | case CPU_ONLINE: |
| 1672 | case CPU_DEAD: |
| 1673 | case CPU_DYING: |
| 1674 | case CPU_DOWN_FAILED: |
| 1675 | case CPU_UP_CANCELED: |
| 1676 | console_lock(); |
| 1677 | console_unlock(); |
| 1678 | } |
| 1679 | return NOTIFY_OK; |
| 1680 | } |
| 1681 | |
| 1682 | /** |
| 1683 | * console_lock - lock the console system for exclusive use. |
| 1684 | * |
| 1685 | * Acquires a lock which guarantees that the caller has |
| 1686 | * exclusive access to the console system and the console_drivers list. |
| 1687 | * |
| 1688 | * Can sleep, returns nothing. |
| 1689 | */ |
| 1690 | void console_lock(void) |
| 1691 | { |
| 1692 | BUG_ON(in_interrupt()); |
| 1693 | down(&console_sem); |
| 1694 | if (console_suspended) |
| 1695 | return; |
| 1696 | console_locked = 1; |
| 1697 | console_may_schedule = 1; |
| 1698 | } |
| 1699 | EXPORT_SYMBOL(console_lock); |
| 1700 | |
| 1701 | /** |
| 1702 | * console_trylock - try to lock the console system for exclusive use. |
| 1703 | * |
| 1704 | * Tried to acquire a lock which guarantees that the caller has |
| 1705 | * exclusive access to the console system and the console_drivers list. |
| 1706 | * |
| 1707 | * returns 1 on success, and 0 on failure to acquire the lock. |
| 1708 | */ |
| 1709 | int console_trylock(void) |
| 1710 | { |
| 1711 | if (down_trylock(&console_sem)) |
| 1712 | return 0; |
| 1713 | if (console_suspended) { |
| 1714 | up(&console_sem); |
| 1715 | return 0; |
| 1716 | } |
| 1717 | console_locked = 1; |
| 1718 | console_may_schedule = 0; |
| 1719 | return 1; |
| 1720 | } |
| 1721 | EXPORT_SYMBOL(console_trylock); |
| 1722 | |
| 1723 | int is_console_locked(void) |
| 1724 | { |
| 1725 | return console_locked; |
| 1726 | } |
| 1727 | |
| 1728 | /* |
| 1729 | * Delayed printk version, for scheduler-internal messages: |
| 1730 | */ |
| 1731 | #define PRINTK_BUF_SIZE 512 |
| 1732 | |
| 1733 | #define PRINTK_PENDING_WAKEUP 0x01 |
| 1734 | #define PRINTK_PENDING_SCHED 0x02 |
| 1735 | |
| 1736 | static DEFINE_PER_CPU(int, printk_pending); |
| 1737 | static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf); |
| 1738 | |
| 1739 | void printk_tick(void) |
| 1740 | { |
| 1741 | if (__this_cpu_read(printk_pending)) { |
| 1742 | int pending = __this_cpu_xchg(printk_pending, 0); |
| 1743 | if (pending & PRINTK_PENDING_SCHED) { |
| 1744 | char *buf = __get_cpu_var(printk_sched_buf); |
| 1745 | printk(KERN_WARNING "[sched_delayed] %s", buf); |
| 1746 | } |
| 1747 | if (pending & PRINTK_PENDING_WAKEUP) |
| 1748 | wake_up_interruptible(&log_wait); |
| 1749 | } |
| 1750 | } |
| 1751 | |
| 1752 | int printk_needs_cpu(int cpu) |
| 1753 | { |
| 1754 | if (cpu_is_offline(cpu)) |
| 1755 | printk_tick(); |
| 1756 | return __this_cpu_read(printk_pending); |
| 1757 | } |
| 1758 | |
| 1759 | void wake_up_klogd(void) |
| 1760 | { |
| 1761 | if (waitqueue_active(&log_wait)) |
| 1762 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); |
| 1763 | } |
| 1764 | |
| 1765 | /* the next printk record to write to the console */ |
| 1766 | static u64 console_seq; |
| 1767 | static u32 console_idx; |
| 1768 | |
| 1769 | /** |
| 1770 | * console_unlock - unlock the console system |
| 1771 | * |
| 1772 | * Releases the console_lock which the caller holds on the console system |
| 1773 | * and the console driver list. |
| 1774 | * |
| 1775 | * While the console_lock was held, console output may have been buffered |
| 1776 | * by printk(). If this is the case, console_unlock(); emits |
| 1777 | * the output prior to releasing the lock. |
| 1778 | * |
| 1779 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
| 1780 | * |
| 1781 | * console_unlock(); may be called from any context. |
| 1782 | */ |
| 1783 | void console_unlock(void) |
| 1784 | { |
| 1785 | static u64 seen_seq; |
| 1786 | unsigned long flags; |
| 1787 | bool wake_klogd = false; |
| 1788 | bool retry; |
| 1789 | |
| 1790 | if (console_suspended) { |
| 1791 | up(&console_sem); |
| 1792 | return; |
| 1793 | } |
| 1794 | |
| 1795 | console_may_schedule = 0; |
| 1796 | |
| 1797 | again: |
| 1798 | for (;;) { |
| 1799 | struct log *msg; |
| 1800 | static char text[LOG_LINE_MAX]; |
| 1801 | size_t len; |
| 1802 | int level; |
| 1803 | |
| 1804 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 1805 | if (seen_seq != log_next_seq) { |
| 1806 | wake_klogd = true; |
| 1807 | seen_seq = log_next_seq; |
| 1808 | } |
| 1809 | |
| 1810 | if (console_seq < log_first_seq) { |
| 1811 | /* messages are gone, move to first one */ |
| 1812 | console_seq = log_first_seq; |
| 1813 | console_idx = log_first_idx; |
| 1814 | } |
| 1815 | |
| 1816 | if (console_seq == log_next_seq) |
| 1817 | break; |
| 1818 | |
| 1819 | msg = log_from_idx(console_idx); |
| 1820 | level = msg->level & 7; |
| 1821 | |
| 1822 | len = msg_print_text(msg, false, text, sizeof(text)); |
| 1823 | |
| 1824 | console_idx = log_next(console_idx); |
| 1825 | console_seq++; |
| 1826 | raw_spin_unlock(&logbuf_lock); |
| 1827 | |
| 1828 | stop_critical_timings(); /* don't trace print latency */ |
| 1829 | call_console_drivers(level, text, len); |
| 1830 | start_critical_timings(); |
| 1831 | local_irq_restore(flags); |
| 1832 | } |
| 1833 | console_locked = 0; |
| 1834 | |
| 1835 | /* Release the exclusive_console once it is used */ |
| 1836 | if (unlikely(exclusive_console)) |
| 1837 | exclusive_console = NULL; |
| 1838 | |
| 1839 | raw_spin_unlock(&logbuf_lock); |
| 1840 | |
| 1841 | up(&console_sem); |
| 1842 | |
| 1843 | /* |
| 1844 | * Someone could have filled up the buffer again, so re-check if there's |
| 1845 | * something to flush. In case we cannot trylock the console_sem again, |
| 1846 | * there's a new owner and the console_unlock() from them will do the |
| 1847 | * flush, no worries. |
| 1848 | */ |
| 1849 | raw_spin_lock(&logbuf_lock); |
| 1850 | retry = console_seq != log_next_seq; |
| 1851 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 1852 | |
| 1853 | if (retry && console_trylock()) |
| 1854 | goto again; |
| 1855 | |
| 1856 | if (wake_klogd) |
| 1857 | wake_up_klogd(); |
| 1858 | } |
| 1859 | EXPORT_SYMBOL(console_unlock); |
| 1860 | |
| 1861 | /** |
| 1862 | * console_conditional_schedule - yield the CPU if required |
| 1863 | * |
| 1864 | * If the console code is currently allowed to sleep, and |
| 1865 | * if this CPU should yield the CPU to another task, do |
| 1866 | * so here. |
| 1867 | * |
| 1868 | * Must be called within console_lock();. |
| 1869 | */ |
| 1870 | void __sched console_conditional_schedule(void) |
| 1871 | { |
| 1872 | if (console_may_schedule) |
| 1873 | cond_resched(); |
| 1874 | } |
| 1875 | EXPORT_SYMBOL(console_conditional_schedule); |
| 1876 | |
| 1877 | void console_unblank(void) |
| 1878 | { |
| 1879 | struct console *c; |
| 1880 | |
| 1881 | /* |
| 1882 | * console_unblank can no longer be called in interrupt context unless |
| 1883 | * oops_in_progress is set to 1.. |
| 1884 | */ |
| 1885 | if (oops_in_progress) { |
| 1886 | if (down_trylock(&console_sem) != 0) |
| 1887 | return; |
| 1888 | } else |
| 1889 | console_lock(); |
| 1890 | |
| 1891 | console_locked = 1; |
| 1892 | console_may_schedule = 0; |
| 1893 | for_each_console(c) |
| 1894 | if ((c->flags & CON_ENABLED) && c->unblank) |
| 1895 | c->unblank(); |
| 1896 | console_unlock(); |
| 1897 | } |
| 1898 | |
| 1899 | /* |
| 1900 | * Return the console tty driver structure and its associated index |
| 1901 | */ |
| 1902 | struct tty_driver *console_device(int *index) |
| 1903 | { |
| 1904 | struct console *c; |
| 1905 | struct tty_driver *driver = NULL; |
| 1906 | |
| 1907 | console_lock(); |
| 1908 | for_each_console(c) { |
| 1909 | if (!c->device) |
| 1910 | continue; |
| 1911 | driver = c->device(c, index); |
| 1912 | if (driver) |
| 1913 | break; |
| 1914 | } |
| 1915 | console_unlock(); |
| 1916 | return driver; |
| 1917 | } |
| 1918 | |
| 1919 | /* |
| 1920 | * Prevent further output on the passed console device so that (for example) |
| 1921 | * serial drivers can disable console output before suspending a port, and can |
| 1922 | * re-enable output afterwards. |
| 1923 | */ |
| 1924 | void console_stop(struct console *console) |
| 1925 | { |
| 1926 | console_lock(); |
| 1927 | console->flags &= ~CON_ENABLED; |
| 1928 | console_unlock(); |
| 1929 | } |
| 1930 | EXPORT_SYMBOL(console_stop); |
| 1931 | |
| 1932 | void console_start(struct console *console) |
| 1933 | { |
| 1934 | console_lock(); |
| 1935 | console->flags |= CON_ENABLED; |
| 1936 | console_unlock(); |
| 1937 | } |
| 1938 | EXPORT_SYMBOL(console_start); |
| 1939 | |
| 1940 | static int __read_mostly keep_bootcon; |
| 1941 | |
| 1942 | static int __init keep_bootcon_setup(char *str) |
| 1943 | { |
| 1944 | keep_bootcon = 1; |
| 1945 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); |
| 1946 | |
| 1947 | return 0; |
| 1948 | } |
| 1949 | |
| 1950 | early_param("keep_bootcon", keep_bootcon_setup); |
| 1951 | |
| 1952 | /* |
| 1953 | * The console driver calls this routine during kernel initialization |
| 1954 | * to register the console printing procedure with printk() and to |
| 1955 | * print any messages that were printed by the kernel before the |
| 1956 | * console driver was initialized. |
| 1957 | * |
| 1958 | * This can happen pretty early during the boot process (because of |
| 1959 | * early_printk) - sometimes before setup_arch() completes - be careful |
| 1960 | * of what kernel features are used - they may not be initialised yet. |
| 1961 | * |
| 1962 | * There are two types of consoles - bootconsoles (early_printk) and |
| 1963 | * "real" consoles (everything which is not a bootconsole) which are |
| 1964 | * handled differently. |
| 1965 | * - Any number of bootconsoles can be registered at any time. |
| 1966 | * - As soon as a "real" console is registered, all bootconsoles |
| 1967 | * will be unregistered automatically. |
| 1968 | * - Once a "real" console is registered, any attempt to register a |
| 1969 | * bootconsoles will be rejected |
| 1970 | */ |
| 1971 | void register_console(struct console *newcon) |
| 1972 | { |
| 1973 | int i; |
| 1974 | unsigned long flags; |
| 1975 | struct console *bcon = NULL; |
| 1976 | |
| 1977 | /* |
| 1978 | * before we register a new CON_BOOT console, make sure we don't |
| 1979 | * already have a valid console |
| 1980 | */ |
| 1981 | if (console_drivers && newcon->flags & CON_BOOT) { |
| 1982 | /* find the last or real console */ |
| 1983 | for_each_console(bcon) { |
| 1984 | if (!(bcon->flags & CON_BOOT)) { |
| 1985 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", |
| 1986 | newcon->name, newcon->index); |
| 1987 | return; |
| 1988 | } |
| 1989 | } |
| 1990 | } |
| 1991 | |
| 1992 | if (console_drivers && console_drivers->flags & CON_BOOT) |
| 1993 | bcon = console_drivers; |
| 1994 | |
| 1995 | if (preferred_console < 0 || bcon || !console_drivers) |
| 1996 | preferred_console = selected_console; |
| 1997 | |
| 1998 | if (newcon->early_setup) |
| 1999 | newcon->early_setup(); |
| 2000 | |
| 2001 | /* |
| 2002 | * See if we want to use this console driver. If we |
| 2003 | * didn't select a console we take the first one |
| 2004 | * that registers here. |
| 2005 | */ |
| 2006 | if (preferred_console < 0) { |
| 2007 | if (newcon->index < 0) |
| 2008 | newcon->index = 0; |
| 2009 | if (newcon->setup == NULL || |
| 2010 | newcon->setup(newcon, NULL) == 0) { |
| 2011 | newcon->flags |= CON_ENABLED; |
| 2012 | if (newcon->device) { |
| 2013 | newcon->flags |= CON_CONSDEV; |
| 2014 | preferred_console = 0; |
| 2015 | } |
| 2016 | } |
| 2017 | } |
| 2018 | |
| 2019 | /* |
| 2020 | * See if this console matches one we selected on |
| 2021 | * the command line. |
| 2022 | */ |
| 2023 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
| 2024 | i++) { |
| 2025 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
| 2026 | continue; |
| 2027 | if (newcon->index >= 0 && |
| 2028 | newcon->index != console_cmdline[i].index) |
| 2029 | continue; |
| 2030 | if (newcon->index < 0) |
| 2031 | newcon->index = console_cmdline[i].index; |
| 2032 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| 2033 | if (console_cmdline[i].brl_options) { |
| 2034 | newcon->flags |= CON_BRL; |
| 2035 | braille_register_console(newcon, |
| 2036 | console_cmdline[i].index, |
| 2037 | console_cmdline[i].options, |
| 2038 | console_cmdline[i].brl_options); |
| 2039 | return; |
| 2040 | } |
| 2041 | #endif |
| 2042 | if (newcon->setup && |
| 2043 | newcon->setup(newcon, console_cmdline[i].options) != 0) |
| 2044 | break; |
| 2045 | newcon->flags |= CON_ENABLED; |
| 2046 | newcon->index = console_cmdline[i].index; |
| 2047 | if (i == selected_console) { |
| 2048 | newcon->flags |= CON_CONSDEV; |
| 2049 | preferred_console = selected_console; |
| 2050 | } |
| 2051 | break; |
| 2052 | } |
| 2053 | |
| 2054 | if (!(newcon->flags & CON_ENABLED)) |
| 2055 | return; |
| 2056 | |
| 2057 | /* |
| 2058 | * If we have a bootconsole, and are switching to a real console, |
| 2059 | * don't print everything out again, since when the boot console, and |
| 2060 | * the real console are the same physical device, it's annoying to |
| 2061 | * see the beginning boot messages twice |
| 2062 | */ |
| 2063 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
| 2064 | newcon->flags &= ~CON_PRINTBUFFER; |
| 2065 | |
| 2066 | /* |
| 2067 | * Put this console in the list - keep the |
| 2068 | * preferred driver at the head of the list. |
| 2069 | */ |
| 2070 | console_lock(); |
| 2071 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
| 2072 | newcon->next = console_drivers; |
| 2073 | console_drivers = newcon; |
| 2074 | if (newcon->next) |
| 2075 | newcon->next->flags &= ~CON_CONSDEV; |
| 2076 | } else { |
| 2077 | newcon->next = console_drivers->next; |
| 2078 | console_drivers->next = newcon; |
| 2079 | } |
| 2080 | if (newcon->flags & CON_PRINTBUFFER) { |
| 2081 | /* |
| 2082 | * console_unlock(); will print out the buffered messages |
| 2083 | * for us. |
| 2084 | */ |
| 2085 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2086 | console_seq = syslog_seq; |
| 2087 | console_idx = syslog_idx; |
| 2088 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2089 | /* |
| 2090 | * We're about to replay the log buffer. Only do this to the |
| 2091 | * just-registered console to avoid excessive message spam to |
| 2092 | * the already-registered consoles. |
| 2093 | */ |
| 2094 | exclusive_console = newcon; |
| 2095 | } |
| 2096 | console_unlock(); |
| 2097 | console_sysfs_notify(); |
| 2098 | |
| 2099 | /* |
| 2100 | * By unregistering the bootconsoles after we enable the real console |
| 2101 | * we get the "console xxx enabled" message on all the consoles - |
| 2102 | * boot consoles, real consoles, etc - this is to ensure that end |
| 2103 | * users know there might be something in the kernel's log buffer that |
| 2104 | * went to the bootconsole (that they do not see on the real console) |
| 2105 | */ |
| 2106 | if (bcon && |
| 2107 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
| 2108 | !keep_bootcon) { |
| 2109 | /* we need to iterate through twice, to make sure we print |
| 2110 | * everything out, before we unregister the console(s) |
| 2111 | */ |
| 2112 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", |
| 2113 | newcon->name, newcon->index); |
| 2114 | for_each_console(bcon) |
| 2115 | if (bcon->flags & CON_BOOT) |
| 2116 | unregister_console(bcon); |
| 2117 | } else { |
| 2118 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", |
| 2119 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
| 2120 | newcon->name, newcon->index); |
| 2121 | } |
| 2122 | } |
| 2123 | EXPORT_SYMBOL(register_console); |
| 2124 | |
| 2125 | int unregister_console(struct console *console) |
| 2126 | { |
| 2127 | struct console *a, *b; |
| 2128 | int res = 1; |
| 2129 | |
| 2130 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
| 2131 | if (console->flags & CON_BRL) |
| 2132 | return braille_unregister_console(console); |
| 2133 | #endif |
| 2134 | |
| 2135 | console_lock(); |
| 2136 | if (console_drivers == console) { |
| 2137 | console_drivers=console->next; |
| 2138 | res = 0; |
| 2139 | } else if (console_drivers) { |
| 2140 | for (a=console_drivers->next, b=console_drivers ; |
| 2141 | a; b=a, a=b->next) { |
| 2142 | if (a == console) { |
| 2143 | b->next = a->next; |
| 2144 | res = 0; |
| 2145 | break; |
| 2146 | } |
| 2147 | } |
| 2148 | } |
| 2149 | |
| 2150 | /* |
| 2151 | * If this isn't the last console and it has CON_CONSDEV set, we |
| 2152 | * need to set it on the next preferred console. |
| 2153 | */ |
| 2154 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
| 2155 | console_drivers->flags |= CON_CONSDEV; |
| 2156 | |
| 2157 | console_unlock(); |
| 2158 | console_sysfs_notify(); |
| 2159 | return res; |
| 2160 | } |
| 2161 | EXPORT_SYMBOL(unregister_console); |
| 2162 | |
| 2163 | static int __init printk_late_init(void) |
| 2164 | { |
| 2165 | struct console *con; |
| 2166 | |
| 2167 | for_each_console(con) { |
| 2168 | if (!keep_bootcon && con->flags & CON_BOOT) { |
| 2169 | printk(KERN_INFO "turn off boot console %s%d\n", |
| 2170 | con->name, con->index); |
| 2171 | unregister_console(con); |
| 2172 | } |
| 2173 | } |
| 2174 | hotcpu_notifier(console_cpu_notify, 0); |
| 2175 | return 0; |
| 2176 | } |
| 2177 | late_initcall(printk_late_init); |
| 2178 | |
| 2179 | #if defined CONFIG_PRINTK |
| 2180 | |
| 2181 | int printk_sched(const char *fmt, ...) |
| 2182 | { |
| 2183 | unsigned long flags; |
| 2184 | va_list args; |
| 2185 | char *buf; |
| 2186 | int r; |
| 2187 | |
| 2188 | local_irq_save(flags); |
| 2189 | buf = __get_cpu_var(printk_sched_buf); |
| 2190 | |
| 2191 | va_start(args, fmt); |
| 2192 | r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args); |
| 2193 | va_end(args); |
| 2194 | |
| 2195 | __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED); |
| 2196 | local_irq_restore(flags); |
| 2197 | |
| 2198 | return r; |
| 2199 | } |
| 2200 | |
| 2201 | /* |
| 2202 | * printk rate limiting, lifted from the networking subsystem. |
| 2203 | * |
| 2204 | * This enforces a rate limit: not more than 10 kernel messages |
| 2205 | * every 5s to make a denial-of-service attack impossible. |
| 2206 | */ |
| 2207 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
| 2208 | |
| 2209 | int __printk_ratelimit(const char *func) |
| 2210 | { |
| 2211 | return ___ratelimit(&printk_ratelimit_state, func); |
| 2212 | } |
| 2213 | EXPORT_SYMBOL(__printk_ratelimit); |
| 2214 | |
| 2215 | /** |
| 2216 | * printk_timed_ratelimit - caller-controlled printk ratelimiting |
| 2217 | * @caller_jiffies: pointer to caller's state |
| 2218 | * @interval_msecs: minimum interval between prints |
| 2219 | * |
| 2220 | * printk_timed_ratelimit() returns true if more than @interval_msecs |
| 2221 | * milliseconds have elapsed since the last time printk_timed_ratelimit() |
| 2222 | * returned true. |
| 2223 | */ |
| 2224 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
| 2225 | unsigned int interval_msecs) |
| 2226 | { |
| 2227 | if (*caller_jiffies == 0 |
| 2228 | || !time_in_range(jiffies, *caller_jiffies, |
| 2229 | *caller_jiffies |
| 2230 | + msecs_to_jiffies(interval_msecs))) { |
| 2231 | *caller_jiffies = jiffies; |
| 2232 | return true; |
| 2233 | } |
| 2234 | return false; |
| 2235 | } |
| 2236 | EXPORT_SYMBOL(printk_timed_ratelimit); |
| 2237 | |
| 2238 | static DEFINE_SPINLOCK(dump_list_lock); |
| 2239 | static LIST_HEAD(dump_list); |
| 2240 | |
| 2241 | /** |
| 2242 | * kmsg_dump_register - register a kernel log dumper. |
| 2243 | * @dumper: pointer to the kmsg_dumper structure |
| 2244 | * |
| 2245 | * Adds a kernel log dumper to the system. The dump callback in the |
| 2246 | * structure will be called when the kernel oopses or panics and must be |
| 2247 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
| 2248 | */ |
| 2249 | int kmsg_dump_register(struct kmsg_dumper *dumper) |
| 2250 | { |
| 2251 | unsigned long flags; |
| 2252 | int err = -EBUSY; |
| 2253 | |
| 2254 | /* The dump callback needs to be set */ |
| 2255 | if (!dumper->dump) |
| 2256 | return -EINVAL; |
| 2257 | |
| 2258 | spin_lock_irqsave(&dump_list_lock, flags); |
| 2259 | /* Don't allow registering multiple times */ |
| 2260 | if (!dumper->registered) { |
| 2261 | dumper->registered = 1; |
| 2262 | list_add_tail_rcu(&dumper->list, &dump_list); |
| 2263 | err = 0; |
| 2264 | } |
| 2265 | spin_unlock_irqrestore(&dump_list_lock, flags); |
| 2266 | |
| 2267 | return err; |
| 2268 | } |
| 2269 | EXPORT_SYMBOL_GPL(kmsg_dump_register); |
| 2270 | |
| 2271 | /** |
| 2272 | * kmsg_dump_unregister - unregister a kmsg dumper. |
| 2273 | * @dumper: pointer to the kmsg_dumper structure |
| 2274 | * |
| 2275 | * Removes a dump device from the system. Returns zero on success and |
| 2276 | * %-EINVAL otherwise. |
| 2277 | */ |
| 2278 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
| 2279 | { |
| 2280 | unsigned long flags; |
| 2281 | int err = -EINVAL; |
| 2282 | |
| 2283 | spin_lock_irqsave(&dump_list_lock, flags); |
| 2284 | if (dumper->registered) { |
| 2285 | dumper->registered = 0; |
| 2286 | list_del_rcu(&dumper->list); |
| 2287 | err = 0; |
| 2288 | } |
| 2289 | spin_unlock_irqrestore(&dump_list_lock, flags); |
| 2290 | synchronize_rcu(); |
| 2291 | |
| 2292 | return err; |
| 2293 | } |
| 2294 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
| 2295 | |
| 2296 | static bool always_kmsg_dump; |
| 2297 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); |
| 2298 | |
| 2299 | /** |
| 2300 | * kmsg_dump - dump kernel log to kernel message dumpers. |
| 2301 | * @reason: the reason (oops, panic etc) for dumping |
| 2302 | * |
| 2303 | * Iterate through each of the dump devices and call the oops/panic |
| 2304 | * callbacks with the log buffer. |
| 2305 | */ |
| 2306 | void kmsg_dump(enum kmsg_dump_reason reason) |
| 2307 | { |
| 2308 | u64 idx; |
| 2309 | struct kmsg_dumper *dumper; |
| 2310 | const char *s1, *s2; |
| 2311 | unsigned long l1, l2; |
| 2312 | unsigned long flags; |
| 2313 | |
| 2314 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
| 2315 | return; |
| 2316 | |
| 2317 | /* Theoretically, the log could move on after we do this, but |
| 2318 | there's not a lot we can do about that. The new messages |
| 2319 | will overwrite the start of what we dump. */ |
| 2320 | |
| 2321 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
| 2322 | if (syslog_seq < log_first_seq) |
| 2323 | idx = syslog_idx; |
| 2324 | else |
| 2325 | idx = log_first_idx; |
| 2326 | |
| 2327 | if (idx > log_next_idx) { |
| 2328 | s1 = log_buf; |
| 2329 | l1 = log_next_idx; |
| 2330 | |
| 2331 | s2 = log_buf + idx; |
| 2332 | l2 = log_buf_len - idx; |
| 2333 | } else { |
| 2334 | s1 = ""; |
| 2335 | l1 = 0; |
| 2336 | |
| 2337 | s2 = log_buf + idx; |
| 2338 | l2 = log_next_idx - idx; |
| 2339 | } |
| 2340 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
| 2341 | |
| 2342 | rcu_read_lock(); |
| 2343 | list_for_each_entry_rcu(dumper, &dump_list, list) |
| 2344 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
| 2345 | rcu_read_unlock(); |
| 2346 | } |
| 2347 | #endif |