// SPDX-License-Identifier: GPL-2.0-only /* * linux/kernel/printk.c * * Copyright (C) 1991, 1992 Linus Torvalds * * Modified to make sys_syslog() more flexible: added commands to * return the last 4k of kernel messages, regardless of whether * they've been read or not. Added option to suppress kernel printk's * to the console. Added hook for sending the console messages * elsewhere, in preparation for a serial line console (someday). * Ted Ts'o, 2/11/93. * Modified for sysctl support, 1/8/97, Chris Horn. * Fixed SMP synchronization, 08/08/99, Manfred Spraul * manfred@colorfullife.com * Rewrote bits to get rid of console_lock * 01Mar01 Andrew Morton */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define CREATE_TRACE_POINTS #include #include "console_cmdline.h" #include "braille.h" int console_printk[5] = { CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ CONSOLE_LOGLEVEL_EMERGENCY, /* emergency_console_loglevel */ }; EXPORT_SYMBOL_GPL(console_printk); atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); EXPORT_SYMBOL(ignore_console_lock_warning); /* * Low level drivers may need that to know if they can schedule in * their unblank() callback or not. So let's export it. */ int oops_in_progress; EXPORT_SYMBOL(oops_in_progress); /* * console_sem protects the console_drivers list, and also * provides serialisation for access to the entire console * driver system. */ static DEFINE_SEMAPHORE(console_sem); struct console *console_drivers; EXPORT_SYMBOL_GPL(console_drivers); /* * System may need to suppress printk message under certain * circumstances, like after kernel panic happens. */ int __read_mostly suppress_printk; #ifdef CONFIG_LOCKDEP static struct lockdep_map console_lock_dep_map = { .name = "console_lock" }; #endif enum devkmsg_log_bits { __DEVKMSG_LOG_BIT_ON = 0, __DEVKMSG_LOG_BIT_OFF, __DEVKMSG_LOG_BIT_LOCK, }; enum devkmsg_log_masks { DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), }; /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ #define DEVKMSG_LOG_MASK_DEFAULT 0 static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; static int __control_devkmsg(char *str) { if (!str) return -EINVAL; if (!strncmp(str, "on", 2)) { devkmsg_log = DEVKMSG_LOG_MASK_ON; return 2; } else if (!strncmp(str, "off", 3)) { devkmsg_log = DEVKMSG_LOG_MASK_OFF; return 3; } else if (!strncmp(str, "ratelimit", 9)) { devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; return 9; } return -EINVAL; } static int __init control_devkmsg(char *str) { if (__control_devkmsg(str) < 0) return 1; /* * Set sysctl string accordingly: */ if (devkmsg_log == DEVKMSG_LOG_MASK_ON) strcpy(devkmsg_log_str, "on"); else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) strcpy(devkmsg_log_str, "off"); /* else "ratelimit" which is set by default. */ /* * Sysctl cannot change it anymore. The kernel command line setting of * this parameter is to force the setting to be permanent throughout the * runtime of the system. This is a precation measure against userspace * trying to be a smarta** and attempting to change it up on us. */ devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; return 0; } __setup("printk.devkmsg=", control_devkmsg); char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { char old_str[DEVKMSG_STR_MAX_SIZE]; unsigned int old; int err; if (write) { if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) return -EINVAL; old = devkmsg_log; strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); } err = proc_dostring(table, write, buffer, lenp, ppos); if (err) return err; if (write) { err = __control_devkmsg(devkmsg_log_str); /* * Do not accept an unknown string OR a known string with * trailing crap... */ if (err < 0 || (err + 1 != *lenp)) { /* ... and restore old setting. */ devkmsg_log = old; strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); return -EINVAL; } } return 0; } /* Number of registered extended console drivers. */ static int nr_ext_console_drivers; /* * Helper macros to handle lockdep when locking/unlocking console_sem. We use * macros instead of functions so that _RET_IP_ contains useful information. */ #define down_console_sem() do { \ down(&console_sem);\ mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ } while (0) static int __down_trylock_console_sem(unsigned long ip) { if (down_trylock(&console_sem)) return 1; mutex_acquire(&console_lock_dep_map, 0, 1, ip); return 0; } #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) static void __up_console_sem(unsigned long ip) { mutex_release(&console_lock_dep_map, 1, ip); up(&console_sem); } #define up_console_sem() __up_console_sem(_RET_IP_) /* * This is used for debugging the mess that is the VT code by * keeping track if we have the console semaphore held. It's * definitely not the perfect debug tool (we don't know if _WE_ * hold it and are racing, but it helps tracking those weird code * paths in the console code where we end up in places I want * locked without the console sempahore held). */ static int console_locked, console_suspended; /* * Array of consoles built from command line options (console=) */ #define MAX_CMDLINECONSOLES 8 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; static int preferred_console = -1; int console_set_on_cmdline; EXPORT_SYMBOL(console_set_on_cmdline); /* Flag: console code may call schedule() */ static int console_may_schedule; enum con_msg_format_flags { MSG_FORMAT_DEFAULT = 0, MSG_FORMAT_SYSLOG = (1 << 0), }; static int console_msg_format = MSG_FORMAT_DEFAULT; /* * The printk log buffer consists of a chain of concatenated variable * length records. Every record starts with a record header, containing * the overall length of the record. * * The heads to the first and last entry in the buffer, as well as the * sequence numbers of these entries are maintained when messages are * stored. * * If the heads indicate available messages, the length in the header * tells the start next message. A length == 0 for the next message * indicates a wrap-around to the beginning of the buffer. * * Every record carries the monotonic timestamp in microseconds, as well as * the standard userspace syslog level and syslog facility. The usual * kernel messages use LOG_KERN; userspace-injected messages always carry * a matching syslog facility, by default LOG_USER. The origin of every * message can be reliably determined that way. * * The human readable log message directly follows the message header. The * length of the message text is stored in the header, the stored message * is not terminated. * * Optionally, a message can carry a dictionary of properties (key/value pairs), * to provide userspace with a machine-readable message context. * * Examples for well-defined, commonly used property names are: * DEVICE=b12:8 device identifier * b12:8 block dev_t * c127:3 char dev_t * n8 netdev ifindex * +sound:card0 subsystem:devname * SUBSYSTEM=pci driver-core subsystem name * * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value * follows directly after a '=' character. Every property is terminated by * a '\0' character. The last property is not terminated. * * Example of a message structure: * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec * 0008 34 00 record is 52 bytes long * 000a 0b 00 text is 11 bytes long * 000c 1f 00 dictionary is 23 bytes long * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) * 0010 69 74 27 73 20 61 20 6c "it's a l" * 69 6e 65 "ine" * 001b 44 45 56 49 43 "DEVIC" * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" * 52 49 56 45 52 3d 62 75 "RIVER=bu" * 67 "g" * 0032 00 00 00 padding to next message header * * The 'struct printk_log' buffer header must never be directly exported to * userspace, it is a kernel-private implementation detail that might * need to be changed in the future, when the requirements change. * * /dev/kmsg exports the structured data in the following line format: * ",,,[,additional_values, ... ];\n" * * Users of the export format should ignore possible additional values * separated by ',', and find the message after the ';' character. * * The optional key/value pairs are attached as continuation lines starting * with a space character and terminated by a newline. All possible * non-prinatable characters are escaped in the "\xff" notation. */ enum log_flags { LOG_NEWLINE = 2, /* text ended with a newline */ LOG_CONT = 8, /* text is a fragment of a continuation line */ }; struct printk_log { u64 ts_nsec; /* timestamp in nanoseconds */ u16 cpu; /* cpu that generated record */ u16 len; /* length of entire record */ u16 text_len; /* length of text buffer */ u16 dict_len; /* length of dictionary buffer */ u8 facility; /* syslog facility */ u8 flags:5; /* internal record flags */ u8 level:3; /* syslog level */ #ifdef CONFIG_PRINTK_CALLER u32 caller_id; /* thread id or processor id */ #endif } #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS __packed __aligned(4) #endif ; DECLARE_STATIC_PRINTKRB_CPULOCK(printk_cpulock); #ifdef CONFIG_PRINTK /* record buffer */ DECLARE_STATIC_PRINTKRB(printk_rb, CONFIG_LOG_BUF_SHIFT, &printk_cpulock); static DEFINE_MUTEX(syslog_lock); DECLARE_STATIC_PRINTKRB_ITER(syslog_iter, &printk_rb); /* the last printk record to read by syslog(READ) or /proc/kmsg */ static u64 syslog_seq; static size_t syslog_partial; static bool syslog_time; /* the next printk record to read after the last 'clear' command */ static u64 clear_seq; #ifdef CONFIG_PRINTK_CALLER #define PREFIX_MAX 48 #else #define PREFIX_MAX 32 #endif #define LOG_LINE_MAX (1024 - PREFIX_MAX) #define LOG_LEVEL(v) ((v) & 0x07) #define LOG_FACILITY(v) ((v) >> 3 & 0xff) /* Return log buffer address */ char *log_buf_addr_get(void) { return printk_rb.buffer; } /* Return log buffer size */ u32 log_buf_len_get(void) { return (1 << printk_rb.size_bits); } /* human readable text of the record */ static char *log_text(const struct printk_log *msg) { return (char *)msg + sizeof(struct printk_log); } /* optional key/value pair dictionary attached to the record */ static char *log_dict(const struct printk_log *msg) { return (char *)msg + sizeof(struct printk_log) + msg->text_len; } static void printk_emergency(char *buffer, int level, u64 ts_nsec, u16 cpu, char *text, u16 text_len); /* insert record into the buffer, discard old ones, update heads */ static int log_store(u32 caller_id, int facility, int level, enum log_flags flags, u64 ts_nsec, u16 cpu, const char *dict, u16 dict_len, const char *text, u16 text_len) { struct printk_log *msg; struct prb_handle h; char *rbuf; u32 size; size = sizeof(*msg) + text_len + dict_len; rbuf = prb_reserve(&h, &printk_rb, size); if (!rbuf) { /* * An emergency message would have been printed, but * it cannot be stored in the log. */ prb_inc_lost(&printk_rb); return 0; } /* fill message */ msg = (struct printk_log *)rbuf; memcpy(log_text(msg), text, text_len); msg->text_len = text_len; memcpy(log_dict(msg), dict, dict_len); msg->dict_len = dict_len; msg->facility = facility; msg->level = level & 7; msg->flags = flags & 0x1f; msg->ts_nsec = ts_nsec; #ifdef CONFIG_PRINTK_CALLER msg->caller_id = caller_id; #endif msg->cpu = cpu; msg->len = size; /* insert message */ prb_commit(&h); return msg->text_len; } int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); static int syslog_action_restricted(int type) { if (dmesg_restrict) return 1; /* * Unless restricted, we allow "read all" and "get buffer size" * for everybody. */ return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; } static int check_syslog_permissions(int type, int source) { /* * If this is from /proc/kmsg and we've already opened it, then we've * already done the capabilities checks at open time. */ if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) goto ok; if (syslog_action_restricted(type)) { if (capable(CAP_SYSLOG)) goto ok; /* * For historical reasons, accept CAP_SYS_ADMIN too, with * a warning. */ if (capable(CAP_SYS_ADMIN)) { pr_warn_once("%s (%d): Attempt to access syslog with " "CAP_SYS_ADMIN but no CAP_SYSLOG " "(deprecated).\n", current->comm, task_pid_nr(current)); goto ok; } return -EPERM; } ok: return security_syslog(type); } static void append_char(char **pp, char *e, char c) { if (*pp < e) *(*pp)++ = c; } static ssize_t msg_print_ext_header(char *buf, size_t size, struct printk_log *msg, u64 seq) { u64 ts_usec = msg->ts_nsec; char caller[20]; #ifdef CONFIG_PRINTK_CALLER u32 id = msg->caller_id; snprintf(caller, sizeof(caller), ",caller=%c%u", id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); #else caller[0] = '\0'; #endif do_div(ts_usec, 1000); return scnprintf(buf, size, "%u,%llu,%llu,%c%s,%hu;", (msg->facility << 3) | msg->level, seq, ts_usec, msg->flags & LOG_CONT ? 'c' : '-', caller, msg->cpu); } static ssize_t msg_print_ext_body(char *buf, size_t size, char *dict, size_t dict_len, char *text, size_t text_len) { char *p = buf, *e = buf + size; size_t i; /* escape non-printable characters */ for (i = 0; i < text_len; i++) { unsigned char c = text[i]; if (c < ' ' || c >= 127 || c == '\\') p += scnprintf(p, e - p, "\\x%02x", c); else append_char(&p, e, c); } append_char(&p, e, '\n'); if (dict_len) { bool line = true; for (i = 0; i < dict_len; i++) { unsigned char c = dict[i]; if (line) { append_char(&p, e, ' '); line = false; } if (c == '\0') { append_char(&p, e, '\n'); line = true; continue; } if (c < ' ' || c >= 127 || c == '\\') { p += scnprintf(p, e - p, "\\x%02x", c); continue; } append_char(&p, e, c); } append_char(&p, e, '\n'); } return p - buf; } #define PRINTK_SPRINT_MAX (LOG_LINE_MAX + PREFIX_MAX) #define PRINTK_RECORD_MAX (sizeof(struct printk_log) + \ CONSOLE_EXT_LOG_MAX + PRINTK_SPRINT_MAX) /* /dev/kmsg - userspace message inject/listen interface */ struct devkmsg_user { u64 seq; struct prb_iterator iter; struct ratelimit_state rs; struct mutex lock; char buf[CONSOLE_EXT_LOG_MAX]; char msgbuf[PRINTK_RECORD_MAX]; }; static __printf(3, 4) __cold int devkmsg_emit(int facility, int level, const char *fmt, ...) { va_list args; int r; va_start(args, fmt); r = vprintk_emit(facility, level, NULL, 0, fmt, args); va_end(args); return r; } static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) { char *buf, *line; int level = default_message_loglevel; int facility = 1; /* LOG_USER */ struct file *file = iocb->ki_filp; struct devkmsg_user *user = file->private_data; size_t len = iov_iter_count(from); ssize_t ret = len; if (!user || len > LOG_LINE_MAX) return -EINVAL; /* Ignore when user logging is disabled. */ if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) return len; /* Ratelimit when not explicitly enabled. */ if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { if (!___ratelimit(&user->rs, current->comm)) return ret; } buf = kmalloc(len+1, GFP_KERNEL); if (buf == NULL) return -ENOMEM; buf[len] = '\0'; if (!copy_from_iter_full(buf, len, from)) { kfree(buf); return -EFAULT; } /* * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace * the decimal value represents 32bit, the lower 3 bit are the log * level, the rest are the log facility. * * If no prefix or no userspace facility is specified, we * enforce LOG_USER, to be able to reliably distinguish * kernel-generated messages from userspace-injected ones. */ line = buf; if (line[0] == '<') { char *endp = NULL; unsigned int u; u = simple_strtoul(line + 1, &endp, 10); if (endp && endp[0] == '>') { level = LOG_LEVEL(u); if (LOG_FACILITY(u) != 0) facility = LOG_FACILITY(u); endp++; len -= endp - line; line = endp; } } devkmsg_emit(facility, level, "%s", line); kfree(buf); return ret; } static ssize_t devkmsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct devkmsg_user *user = file->private_data; struct prb_iterator backup_iter; struct printk_log *msg; ssize_t ret; size_t len; u64 seq; if (!user) return -EBADF; ret = mutex_lock_interruptible(&user->lock); if (ret) return ret; /* make a backup copy in case there is a problem */ prb_iter_copy(&backup_iter, &user->iter); if (file->f_flags & O_NONBLOCK) { ret = prb_iter_next(&user->iter, &user->msgbuf[0], sizeof(user->msgbuf), &seq); } else { ret = prb_iter_wait_next(&user->iter, &user->msgbuf[0], sizeof(user->msgbuf), &seq); } if (ret == 0) { /* end of list */ ret = -EAGAIN; goto out; } else if (ret == -EINVAL) { /* iterator invalid, return error and reset */ ret = -EPIPE; prb_iter_init(&user->iter, &printk_rb, &user->seq); goto out; } else if (ret < 0) { /* interrupted by signal */ goto out; } user->seq++; if (user->seq < seq) { ret = -EPIPE; goto restore_out; } msg = (struct printk_log *)&user->msgbuf[0]; len = msg_print_ext_header(user->buf, sizeof(user->buf), msg, user->seq); len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, log_dict(msg), msg->dict_len, log_text(msg), msg->text_len); if (len > count) { ret = -EINVAL; goto restore_out; } if (copy_to_user(buf, user->buf, len)) { ret = -EFAULT; goto restore_out; } ret = len; goto out; restore_out: /* * There was an error, but this message should not be * lost because of it. Restore the backup and setup * seq so that it will work with the next read. */ prb_iter_copy(&user->iter, &backup_iter); user->seq = seq - 1; out: mutex_unlock(&user->lock); return ret; } static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) { struct devkmsg_user *user = file->private_data; loff_t ret; u64 seq; if (!user) return -EBADF; if (offset) return -ESPIPE; ret = mutex_lock_interruptible(&user->lock); if (ret) return ret; switch (whence) { case SEEK_SET: /* the first record */ prb_iter_init(&user->iter, &printk_rb, &user->seq); break; case SEEK_DATA: /* * The first record after the last SYSLOG_ACTION_CLEAR, * like issued by 'dmesg -c'. Reading /dev/kmsg itself * changes no global state, and does not clear anything. */ for (;;) { prb_iter_init(&user->iter, &printk_rb, &seq); ret = prb_iter_seek(&user->iter, clear_seq); if (ret > 0) { /* seeked to clear seq */ user->seq = clear_seq; break; } else if (ret == 0) { /* * The end of the list was hit without * ever seeing the clear seq. Just * seek to the beginning of the list. */ prb_iter_init(&user->iter, &printk_rb, &user->seq); break; } /* iterator invalid, start over */ /* reset clear_seq if it is no longer available */ if (seq > clear_seq) clear_seq = 0; } ret = 0; break; case SEEK_END: /* after the last record */ for (;;) { ret = prb_iter_next(&user->iter, NULL, 0, &user->seq); if (ret == 0) break; else if (ret > 0) continue; /* iterator invalid, start over */ prb_iter_init(&user->iter, &printk_rb, &user->seq); } ret = 0; break; default: ret = -EINVAL; } mutex_unlock(&user->lock); return ret; } struct wait_queue_head *printk_wait_queue(void) { /* FIXME: using prb internals! */ return printk_rb.wq; } static __poll_t devkmsg_poll(struct file *file, poll_table *wait) { struct devkmsg_user *user = file->private_data; struct prb_iterator iter; __poll_t ret = 0; int rbret; u64 seq; if (!user) return EPOLLERR|EPOLLNVAL; poll_wait(file, printk_wait_queue(), wait); mutex_lock(&user->lock); /* use copy so no actual iteration takes place */ prb_iter_copy(&iter, &user->iter); rbret = prb_iter_next(&iter, &user->msgbuf[0], sizeof(user->msgbuf), &seq); if (rbret == 0) goto out; ret = EPOLLIN|EPOLLRDNORM; if (rbret < 0 || (seq - user->seq) != 1) ret |= EPOLLERR|EPOLLPRI; out: mutex_unlock(&user->lock); return ret; } static int devkmsg_open(struct inode *inode, struct file *file) { struct devkmsg_user *user; int err; if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) return -EPERM; /* write-only does not need any file context */ if ((file->f_flags & O_ACCMODE) != O_WRONLY) { err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, SYSLOG_FROM_READER); if (err) return err; } user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); if (!user) return -ENOMEM; ratelimit_default_init(&user->rs); ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); mutex_init(&user->lock); prb_iter_init(&user->iter, &printk_rb, &user->seq); file->private_data = user; return 0; } static int devkmsg_release(struct inode *inode, struct file *file) { struct devkmsg_user *user = file->private_data; if (!user) return 0; ratelimit_state_exit(&user->rs); mutex_destroy(&user->lock); kfree(user); return 0; } const struct file_operations kmsg_fops = { .open = devkmsg_open, .read = devkmsg_read, .write_iter = devkmsg_write, .llseek = devkmsg_llseek, .poll = devkmsg_poll, .release = devkmsg_release, }; #ifdef CONFIG_CRASH_CORE /* * This appends the listed symbols to /proc/vmcore * * /proc/vmcore is used by various utilities, like crash and makedumpfile to * obtain access to symbols that are otherwise very difficult to locate. These * symbols are specifically used so that utilities can access and extract the * dmesg log from a vmcore file after a crash. */ void log_buf_vmcoreinfo_setup(void) { /* * Export struct printk_log size and field offsets. User space tools can * parse it and detect any changes to structure down the line. */ VMCOREINFO_STRUCT_SIZE(printk_log); VMCOREINFO_OFFSET(printk_log, ts_nsec); VMCOREINFO_OFFSET(printk_log, len); VMCOREINFO_OFFSET(printk_log, text_len); VMCOREINFO_OFFSET(printk_log, dict_len); #ifdef CONFIG_PRINTK_CALLER VMCOREINFO_OFFSET(printk_log, caller_id); #endif } #endif /* FIXME: no support for buffer resizing */ #if 0 /* requested log_buf_len from kernel cmdline */ static unsigned long __initdata new_log_buf_len; /* we practice scaling the ring buffer by powers of 2 */ static void __init log_buf_len_update(u64 size) { if (size > (u64)LOG_BUF_LEN_MAX) { size = (u64)LOG_BUF_LEN_MAX; pr_err("log_buf over 2G is not supported.\n"); } if (size) size = roundup_pow_of_two(size); if (size > log_buf_len) new_log_buf_len = (unsigned long)size; } /* save requested log_buf_len since it's too early to process it */ static int __init log_buf_len_setup(char *str) { u64 size; if (!str) return -EINVAL; size = memparse(str, &str); log_buf_len_update(size); return 0; } early_param("log_buf_len", log_buf_len_setup); #ifdef CONFIG_SMP #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) static void __init log_buf_add_cpu(void) { unsigned int cpu_extra; /* * archs should set up cpu_possible_bits properly with * set_cpu_possible() after setup_arch() but just in * case lets ensure this is valid. */ if (num_possible_cpus() == 1) return; cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; /* by default this will only continue through for large > 64 CPUs */ if (cpu_extra <= __LOG_BUF_LEN / 2) return; pr_info("log_buf_len individual max cpu contribution: %d bytes\n", __LOG_CPU_MAX_BUF_LEN); pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", cpu_extra); pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); log_buf_len_update(cpu_extra + __LOG_BUF_LEN); } #else /* !CONFIG_SMP */ static inline void log_buf_add_cpu(void) {} #endif /* CONFIG_SMP */ #endif /* 0 */ void __init setup_log_buf(int early) { /* FIXME: no support for buffer resizing */ #if 0 unsigned long flags; char *new_log_buf; unsigned int free; if (log_buf != __log_buf) return; if (!early && !new_log_buf_len) log_buf_add_cpu(); if (!new_log_buf_len) return; new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN); if (unlikely(!new_log_buf)) { pr_err("log_buf_len: %lu bytes not available\n", new_log_buf_len); return; } logbuf_lock_irqsave(flags); log_buf_len = new_log_buf_len; log_buf = new_log_buf; new_log_buf_len = 0; free = __LOG_BUF_LEN - log_next_idx; memcpy(log_buf, __log_buf, __LOG_BUF_LEN); logbuf_unlock_irqrestore(flags); pr_info("log_buf_len: %u bytes\n", log_buf_len); pr_info("early log buf free: %u(%u%%)\n", free, (free * 100) / __LOG_BUF_LEN); #endif } static bool __read_mostly ignore_loglevel; static int __init ignore_loglevel_setup(char *str) { ignore_loglevel = true; pr_info("debug: ignoring loglevel setting.\n"); return 0; } early_param("ignore_loglevel", ignore_loglevel_setup); module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting (prints all kernel messages to the console)"); static bool suppress_message_printing(int level) { return (level >= console_loglevel && !ignore_loglevel); } #ifdef CONFIG_BOOT_PRINTK_DELAY static int boot_delay; /* msecs delay after each printk during bootup */ static unsigned long long loops_per_msec; /* based on boot_delay */ static int __init boot_delay_setup(char *str) { unsigned long lpj; lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ loops_per_msec = (unsigned long long)lpj / 1000 * HZ; get_option(&str, &boot_delay); if (boot_delay > 10 * 1000) boot_delay = 0; pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " "HZ: %d, loops_per_msec: %llu\n", boot_delay, preset_lpj, lpj, HZ, loops_per_msec); return 0; } early_param("boot_delay", boot_delay_setup); static void boot_delay_msec(int level) { unsigned long long k; unsigned long timeout; if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) || suppress_message_printing(level)) { return; } k = (unsigned long long)loops_per_msec * boot_delay; timeout = jiffies + msecs_to_jiffies(boot_delay); while (k) { k--; cpu_relax(); /* * use (volatile) jiffies to prevent * compiler reduction; loop termination via jiffies * is secondary and may or may not happen. */ if (time_after(jiffies, timeout)) break; touch_nmi_watchdog(); } } #else static inline void boot_delay_msec(int level) { } #endif static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); static size_t print_cpu(u16 cpu, char *buf) { return sprintf(buf, "%03hu: ", cpu); } static size_t print_syslog(unsigned int level, char *buf) { return sprintf(buf, "<%u>", level); } static size_t print_time(u64 ts, char *buf) { unsigned long rem_nsec = do_div(ts, 1000000000); return sprintf(buf, "[%5lu.%06lu]", (unsigned long)ts, rem_nsec / 1000); } #ifdef CONFIG_PRINTK_CALLER static size_t print_caller(u32 id, char *buf) { char caller[12]; snprintf(caller, sizeof(caller), "%c%u", id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); return sprintf(buf, "[%6s]", caller); } #else #define print_caller(id, buf) 0 #endif static size_t print_prefix(const struct printk_log *msg, bool syslog, bool time, char *buf) { size_t len = 0; if (syslog) len = print_syslog((msg->facility << 3) | msg->level, buf); if (time) len += print_time(msg->ts_nsec, buf + len); len += print_caller(msg->caller_id, buf + len); if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { buf[len++] = ' '; buf[len] = '\0'; } len += print_cpu(msg->cpu, buf + len); return len; } static size_t msg_print_text(const struct printk_log *msg, bool syslog, bool time, char *buf, size_t size) { const char *text = log_text(msg); size_t text_size = msg->text_len; size_t len = 0; char prefix[PREFIX_MAX]; const size_t prefix_len = print_prefix(msg, syslog, time, prefix); do { const char *next = memchr(text, '\n', text_size); size_t text_len; if (next) { text_len = next - text; next++; text_size -= next - text; } else { text_len = text_size; } if (buf) { if (prefix_len + text_len + 1 >= size - len) break; memcpy(buf + len, prefix, prefix_len); len += prefix_len; memcpy(buf + len, text, text_len); len += text_len; buf[len++] = '\n'; } else { /* SYSLOG_ACTION_* buffer size only calculation */ len += prefix_len + text_len + 1; } text = next; } while (text); return len; } static int syslog_print(char __user *buf, int size, char *text, char *msgbuf, int *locked) { struct prb_iterator iter; struct printk_log *msg; int len = 0; u64 seq; int ret; while (size > 0) { size_t n; size_t skip; for (;;) { prb_iter_copy(&iter, &syslog_iter); ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &seq); if (ret < 0) { /* messages are gone, move to first one */ prb_iter_init(&syslog_iter, &printk_rb, &syslog_seq); syslog_partial = 0; continue; } break; } if (ret == 0) break; /* * If messages have been missed, the partial tracker * is no longer valid and must be reset. */ if (syslog_seq > 0 && seq - 1 != syslog_seq) { syslog_seq = seq - 1; syslog_partial = 0; } /* * To keep reading/counting partial line consistent, * use printk_time value as of the beginning of a line. */ if (!syslog_partial) syslog_time = printk_time; msg = (struct printk_log *)msgbuf; skip = syslog_partial; n = msg_print_text(msg, true, syslog_time, text, PRINTK_SPRINT_MAX); if (n - syslog_partial <= size) { /* message fits into buffer, move forward */ prb_iter_next(&syslog_iter, NULL, 0, &syslog_seq); n -= syslog_partial; syslog_partial = 0; } else if (!len) { /* partial read(), remember position */ n = size; syslog_partial += n; } else n = 0; if (!n) break; mutex_unlock(&syslog_lock); if (copy_to_user(buf, text + skip, n)) { if (!len) len = -EFAULT; *locked = 0; break; } ret = mutex_lock_interruptible(&syslog_lock); len += n; size -= n; buf += n; if (ret) { if (!len) len = ret; *locked = 0; break; } } return len; } static int count_remaining(struct prb_iterator *iter, u64 until_seq, char *msgbuf, int size, bool records, bool time) { struct prb_iterator local_iter; struct printk_log *msg; int len = 0; u64 seq; int ret; prb_iter_copy(&local_iter, iter); for (;;) { ret = prb_iter_next(&local_iter, msgbuf, size, &seq); if (ret == 0) { break; } else if (ret < 0) { /* the iter is invalid, restart from head */ prb_iter_init(&local_iter, &printk_rb, NULL); len = 0; continue; } if (until_seq && seq >= until_seq) break; if (records) { len++; } else { msg = (struct printk_log *)msgbuf; len += msg_print_text(msg, true, time, NULL, 0); } } return len; } static void syslog_clear(void) { struct prb_iterator iter; int ret; prb_iter_init(&iter, &printk_rb, &clear_seq); for (;;) { ret = prb_iter_next(&iter, NULL, 0, &clear_seq); if (ret == 0) break; else if (ret < 0) prb_iter_init(&iter, &printk_rb, &clear_seq); } } static int syslog_print_all(char __user *buf, int size, bool clear) { struct prb_iterator iter; struct printk_log *msg; char *msgbuf = NULL; char *text = NULL; int textlen; u64 seq = 0; int len = 0; bool time; int ret; text = kmalloc(PRINTK_SPRINT_MAX, GFP_KERNEL); if (!text) return -ENOMEM; msgbuf = kmalloc(PRINTK_RECORD_MAX, GFP_KERNEL); if (!msgbuf) { kfree(text); return -ENOMEM; } time = printk_time; /* * Setup iter to last event before clear. Clear may * be lost, but keep going with a best effort. */ prb_iter_init(&iter, &printk_rb, NULL); prb_iter_seek(&iter, clear_seq); /* count the total bytes after clear */ len = count_remaining(&iter, 0, msgbuf, PRINTK_RECORD_MAX, false, time); /* move iter forward until length fits into the buffer */ while (len > size) { ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &seq); if (ret == 0) { break; } else if (ret < 0) { /* * The iter is now invalid so clear will * also be invalid. Restart from the head. */ prb_iter_init(&iter, &printk_rb, NULL); len = count_remaining(&iter, 0, msgbuf, PRINTK_RECORD_MAX, false, time); continue; } msg = (struct printk_log *)msgbuf; len -= msg_print_text(msg, true, time, NULL, 0); if (clear) clear_seq = seq; } /* copy messages to buffer */ len = 0; while (len >= 0 && len < size) { if (clear) clear_seq = seq; ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &seq); if (ret == 0) { break; } else if (ret < 0) { /* * The iter is now invalid. Make a best * effort to grab the rest of the log * from the new head. */ prb_iter_init(&iter, &printk_rb, NULL); continue; } msg = (struct printk_log *)msgbuf; textlen = msg_print_text(msg, true, time, text, PRINTK_SPRINT_MAX); if (textlen < 0) { len = textlen; break; } if (len + textlen > size) break; if (copy_to_user(buf + len, text, textlen)) len = -EFAULT; else len += textlen; } if (clear && !seq) syslog_clear(); if (text) kfree(text); if (msgbuf) kfree(msgbuf); return len; } int do_syslog(int type, char __user *buf, int len, int source) { bool clear = false; static int saved_console_loglevel = LOGLEVEL_DEFAULT; struct prb_iterator iter; char *msgbuf = NULL; char *text = NULL; int locked; int error; int ret; error = check_syslog_permissions(type, source); if (error) return error; switch (type) { case SYSLOG_ACTION_CLOSE: /* Close log */ break; case SYSLOG_ACTION_OPEN: /* Open log */ break; case SYSLOG_ACTION_READ: /* Read from log */ if (!buf || len < 0) return -EINVAL; if (!len) return 0; if (!access_ok(buf, len)) return -EFAULT; text = kmalloc(PRINTK_SPRINT_MAX, GFP_KERNEL); msgbuf = kmalloc(PRINTK_RECORD_MAX, GFP_KERNEL); if (!text || !msgbuf) { error = -ENOMEM; goto out; } error = mutex_lock_interruptible(&syslog_lock); if (error) goto out; /* * Wait until a first message is available. Use a copy * because no iteration should occur for syslog now. */ for (;;) { prb_iter_copy(&iter, &syslog_iter); mutex_unlock(&syslog_lock); ret = prb_iter_wait_next(&iter, NULL, 0, NULL); if (ret == -ERESTARTSYS) { error = ret; goto out; } error = mutex_lock_interruptible(&syslog_lock); if (error) goto out; if (ret == -EINVAL) { prb_iter_init(&syslog_iter, &printk_rb, &syslog_seq); syslog_partial = 0; continue; } break; } /* print as much as will fit in the user buffer */ locked = 1; error = syslog_print(buf, len, text, msgbuf, &locked); if (locked) mutex_unlock(&syslog_lock); break; /* Read/clear last kernel messages */ case SYSLOG_ACTION_READ_CLEAR: clear = true; /* FALL THRU */ /* Read last kernel messages */ case SYSLOG_ACTION_READ_ALL: if (!buf || len < 0) return -EINVAL; if (!len) return 0; if (!access_ok(buf, len)) return -EFAULT; error = syslog_print_all(buf, len, clear); break; /* Clear ring buffer */ case SYSLOG_ACTION_CLEAR: syslog_clear(); break; /* Disable logging to console */ case SYSLOG_ACTION_CONSOLE_OFF: if (saved_console_loglevel == LOGLEVEL_DEFAULT) saved_console_loglevel = console_loglevel; console_loglevel = minimum_console_loglevel; break; /* Enable logging to console */ case SYSLOG_ACTION_CONSOLE_ON: if (saved_console_loglevel != LOGLEVEL_DEFAULT) { console_loglevel = saved_console_loglevel; saved_console_loglevel = LOGLEVEL_DEFAULT; } break; /* Set level of messages printed to console */ case SYSLOG_ACTION_CONSOLE_LEVEL: if (len < 1 || len > 8) return -EINVAL; if (len < minimum_console_loglevel) len = minimum_console_loglevel; console_loglevel = len; /* Implicitly re-enable logging to console */ saved_console_loglevel = LOGLEVEL_DEFAULT; break; /* Number of chars in the log buffer */ case SYSLOG_ACTION_SIZE_UNREAD: msgbuf = kmalloc(PRINTK_RECORD_MAX, GFP_KERNEL); if (!msgbuf) return -ENOMEM; error = mutex_lock_interruptible(&syslog_lock); if (error) goto out; if (source == SYSLOG_FROM_PROC) { /* * Short-cut for poll(/"proc/kmsg") which simply checks * for pending data, not the size; return the count of * records, not the length. */ error = count_remaining(&syslog_iter, 0, msgbuf, PRINTK_RECORD_MAX, true, printk_time); } else { error = count_remaining(&syslog_iter, 0, msgbuf, PRINTK_RECORD_MAX, false, printk_time); error -= syslog_partial; } mutex_unlock(&syslog_lock); break; /* Size of the log buffer */ case SYSLOG_ACTION_SIZE_BUFFER: error = prb_buffer_size(&printk_rb); break; default: error = -EINVAL; break; } out: if (msgbuf) kfree(msgbuf); if (text) kfree(text); return error; } SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) { return do_syslog(type, buf, len, SYSLOG_FROM_READER); } int printk_delay_msec __read_mostly; static inline void printk_delay(int level) { boot_delay_msec(level); if (unlikely(printk_delay_msec)) { int m = printk_delay_msec; while (m--) { mdelay(1); touch_nmi_watchdog(); } } } static void print_console_dropped(struct console *con, u64 count) { char text[64]; int len; len = sprintf(text, "** %llu printk message%s dropped **\n", count, count > 1 ? "s" : ""); con->write(con, text, len); } static void format_text(struct printk_log *msg, u64 seq, char *ext_text, size_t *ext_len, char *text, size_t *len, bool time) { if (suppress_message_printing(msg->level)) { /* * Skip record that has level above the console * loglevel and update each console's local seq. */ *len = 0; *ext_len = 0; return; } *len = msg_print_text(msg, console_msg_format & MSG_FORMAT_SYSLOG, time, text, PRINTK_SPRINT_MAX); if (nr_ext_console_drivers) { *ext_len = msg_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, msg, seq); *ext_len += msg_print_ext_body(ext_text + *ext_len, CONSOLE_EXT_LOG_MAX - *ext_len, log_dict(msg), msg->dict_len, log_text(msg), msg->text_len); } else { *ext_len = 0; } } static void printk_write_history(struct console *con, u64 master_seq) { struct prb_iterator iter; bool time = printk_time; static char *ext_text; static char *text; static char *buf; u64 seq; ext_text = kmalloc(CONSOLE_EXT_LOG_MAX, GFP_KERNEL); text = kmalloc(PRINTK_SPRINT_MAX, GFP_KERNEL); buf = kmalloc(PRINTK_RECORD_MAX, GFP_KERNEL); if (!ext_text || !text || !buf) return; if (!(con->flags & CON_ENABLED)) goto out; if (!con->write) goto out; if (!cpu_online(raw_smp_processor_id()) && !(con->flags & CON_ANYTIME)) goto out; prb_iter_init(&iter, &printk_rb, NULL); for (;;) { struct printk_log *msg; size_t ext_len; size_t len; int ret; ret = prb_iter_next(&iter, buf, PRINTK_RECORD_MAX, &seq); if (ret == 0) { break; } else if (ret < 0) { prb_iter_init(&iter, &printk_rb, NULL); continue; } if (seq > master_seq) break; con->printk_seq++; if (con->printk_seq < seq) { print_console_dropped(con, seq - con->printk_seq); con->printk_seq = seq; } msg = (struct printk_log *)buf; format_text(msg, master_seq, ext_text, &ext_len, text, &len, time); if (len == 0 && ext_len == 0) continue; if (con->flags & CON_EXTENDED) con->write(con, ext_text, ext_len); else con->write(con, text, len); printk_delay(msg->level); } out: con->wrote_history = 1; kfree(ext_text); kfree(text); kfree(buf); } /* * Call the console drivers, asking them to write out * log_buf[start] to log_buf[end - 1]. * The console_lock must be held. */ static void call_console_drivers(u64 seq, const char *ext_text, size_t ext_len, const char *text, size_t len, int level, int facility) { struct console *con; trace_console_rcuidle(text, len); if (!console_drivers) return; for_each_console(con) { if (!(con->flags & CON_ENABLED)) continue; if (!con->wrote_history) { if (con->flags & CON_PRINTBUFFER) { printk_write_history(con, seq); continue; } con->wrote_history = 1; con->printk_seq = seq - 1; } if (con->write_atomic && level < emergency_console_loglevel && facility == 0) { /* skip emergency messages, already printed */ if (con->printk_seq < seq) con->printk_seq = seq; continue; } if (con->flags & CON_BOOT && facility == 0) { /* skip emergency messages, already printed */ if (con->printk_seq < seq) con->printk_seq = seq; continue; } if (!con->write) continue; if (!cpu_online(raw_smp_processor_id()) && !(con->flags & CON_ANYTIME)) continue; if (con->printk_seq >= seq) continue; con->printk_seq++; if (con->printk_seq < seq) { print_console_dropped(con, seq - con->printk_seq); con->printk_seq = seq; } /* for supressed messages, only seq is updated */ if (len == 0 && ext_len == 0) continue; if (con->flags & CON_EXTENDED) con->write(con, ext_text, ext_len); else con->write(con, text, len); } } static inline u32 printk_caller_id(void) { return in_task() ? task_pid_nr(current) : 0x80000000 + raw_smp_processor_id(); } /* * Continuation lines are buffered, and not committed to the record buffer * until the line is complete, or a race forces it. The line fragments * though, are printed immediately to the consoles to ensure everything has * reached the console in case of a kernel crash. */ static struct cont { char buf[LOG_LINE_MAX]; size_t len; /* length == 0 means unused buffer */ u32 caller_id; /* printk_caller_id() of first print */ int cpu_owner; /* cpu of first print */ u64 ts_nsec; /* time of first print */ u8 level; /* log level of first message */ u8 facility; /* log facility of first message */ enum log_flags flags; /* prefix, newline flags */ } cont[2]; static void cont_flush(int ctx) { struct cont *c = &cont[ctx]; if (c->len == 0) return; log_store(c->caller_id, c->facility, c->level, c->flags, c->ts_nsec, c->cpu_owner, NULL, 0, c->buf, c->len); c->len = 0; } static void cont_add(int ctx, int cpu, u32 caller_id, int facility, int level, enum log_flags flags, const char *text, size_t len) { struct cont *c = &cont[ctx]; if (cpu != c->cpu_owner || !(flags & LOG_CONT)) cont_flush(ctx); /* If the line gets too long, split it up in separate records. */ while (c->len + len > sizeof(c->buf)) cont_flush(ctx); if (!c->len) { c->facility = facility; c->level = level; c->caller_id = caller_id; c->ts_nsec = local_clock(); c->flags = flags; c->cpu_owner = cpu; } memcpy(c->buf + c->len, text, len); c->len += len; // The original flags come from the first line, // but later continuations can add a newline. if (flags & LOG_NEWLINE) { c->flags |= LOG_NEWLINE; } } /* ring buffer used as memory allocator for temporary sprint buffers */ DECLARE_STATIC_PRINTKRB(sprint_rb, ilog2(PRINTK_RECORD_MAX + sizeof(struct prb_entry) + sizeof(long)) + 2, &printk_cpulock); asmlinkage int vprintk_emit(int facility, int level, const char *dict, size_t dictlen, const char *fmt, va_list args) { const u32 caller_id = printk_caller_id(); int ctx = !!in_nmi(); enum log_flags lflags = 0; int printed_len = 0; struct prb_handle h; size_t text_len; u64 ts_nsec; char *text; char *rbuf; int cpu; ts_nsec = local_clock(); rbuf = prb_reserve(&h, &sprint_rb, PRINTK_SPRINT_MAX); if (!rbuf) { prb_inc_lost(&printk_rb); return printed_len; } cpu = raw_smp_processor_id(); /* * If this turns out to be an emergency message, there * may need to be a prefix added. Leave room for it. */ text = rbuf + PREFIX_MAX; text_len = vscnprintf(text, PRINTK_SPRINT_MAX - PREFIX_MAX, fmt, args); /* strip and flag a trailing newline */ if (text_len && text[text_len-1] == '\n') { text_len--; lflags |= LOG_NEWLINE; } /* strip kernel syslog prefix and extract log level or control flags */ if (facility == 0) { int kern_level; while ((kern_level = printk_get_level(text)) != 0) { switch (kern_level) { case '0' ... '7': if (level == LOGLEVEL_DEFAULT) level = kern_level - '0'; break; case 'c': /* KERN_CONT */ lflags |= LOG_CONT; } text_len -= 2; text += 2; } } if (level == LOGLEVEL_DEFAULT) level = default_message_loglevel; if (dict) lflags |= LOG_NEWLINE; /* * NOTE: * - rbuf points to beginning of allocated buffer * - text points to beginning of text * - there is room before text for prefix */ if (facility == 0) { /* only the kernel can create emergency messages */ printk_emergency(rbuf, level & 7, ts_nsec, cpu, text, text_len); } if ((lflags & LOG_CONT) || !(lflags & LOG_NEWLINE)) { cont_add(ctx, cpu, caller_id, facility, level, lflags, text, text_len); printed_len = text_len; } else { if (cpu == cont[ctx].cpu_owner) cont_flush(ctx); printed_len = log_store(caller_id, facility, level, lflags, ts_nsec, cpu, dict, dictlen, text, text_len); } prb_commit(&h); return printed_len; } EXPORT_SYMBOL(vprintk_emit); static __printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); } asmlinkage int vprintk(const char *fmt, va_list args) { return vprintk_func(fmt, args); } EXPORT_SYMBOL(vprintk); int vprintk_default(const char *fmt, va_list args) { int r; #ifdef CONFIG_KGDB_KDB /* Allow to pass printk() to kdb but avoid a recursion. */ if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) { r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); return r; } #endif r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); return r; } EXPORT_SYMBOL_GPL(vprintk_default); /** * printk - print a kernel message * @fmt: format string * * This is printk(). It can be called from any context. We want it to work. * * We try to grab the console_lock. If we succeed, it's easy - we log the * output and call the console drivers. If we fail to get the semaphore, we * place the output into the log buffer and return. The current holder of * the console_sem will notice the new output in console_unlock(); and will * send it to the consoles before releasing the lock. * * One effect of this deferred printing is that code which calls printk() and * then changes console_loglevel may break. This is because console_loglevel * is inspected when the actual printing occurs. * * See also: * printf(3) * * See the vsnprintf() documentation for format string extensions over C99. */ asmlinkage __visible int printk(const char *fmt, ...) { va_list args; int r; va_start(args, fmt); r = vprintk_func(fmt, args); va_end(args); return r; } EXPORT_SYMBOL(printk); #endif /* CONFIG_PRINTK */ #ifdef CONFIG_EARLY_PRINTK struct console *early_console; asmlinkage __visible void early_printk(const char *fmt, ...) { va_list ap; char buf[512]; int n; if (!early_console) return; va_start(ap, fmt); n = vscnprintf(buf, sizeof(buf), fmt, ap); va_end(ap); early_console->write(early_console, buf, n); } #endif static int __add_preferred_console(char *name, int idx, char *options, char *brl_options) { struct console_cmdline *c; int i; /* * See if this tty is not yet registered, and * if we have a slot free. */ for (i = 0, c = console_cmdline; i < MAX_CMDLINECONSOLES && c->name[0]; i++, c++) { if (strcmp(c->name, name) == 0 && c->index == idx) { if (!brl_options) preferred_console = i; return 0; } } if (i == MAX_CMDLINECONSOLES) return -E2BIG; if (!brl_options) preferred_console = i; strlcpy(c->name, name, sizeof(c->name)); c->options = options; braille_set_options(c, brl_options); c->index = idx; return 0; } static int __init console_msg_format_setup(char *str) { if (!strcmp(str, "syslog")) console_msg_format = MSG_FORMAT_SYSLOG; if (!strcmp(str, "default")) console_msg_format = MSG_FORMAT_DEFAULT; return 1; } __setup("console_msg_format=", console_msg_format_setup); /* * Set up a console. Called via do_early_param() in init/main.c * for each "console=" parameter in the boot command line. */ static int __init console_setup(char *str) { char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ char *s, *options, *brl_options = NULL; int idx; if (_braille_console_setup(&str, &brl_options)) return 1; /* * Decode str into name, index, options. */ if (str[0] >= '0' && str[0] <= '9') { strcpy(buf, "ttyS"); strncpy(buf + 4, str, sizeof(buf) - 5); } else { strncpy(buf, str, sizeof(buf) - 1); } buf[sizeof(buf) - 1] = 0; options = strchr(str, ','); if (options) *(options++) = 0; #ifdef __sparc__ if (!strcmp(str, "ttya")) strcpy(buf, "ttyS0"); if (!strcmp(str, "ttyb")) strcpy(buf, "ttyS1"); #endif for (s = buf; *s; s++) if (isdigit(*s) || *s == ',') break; idx = simple_strtoul(s, NULL, 10); *s = 0; __add_preferred_console(buf, idx, options, brl_options); console_set_on_cmdline = 1; return 1; } __setup("console=", console_setup); /** * add_preferred_console - add a device to the list of preferred consoles. * @name: device name * @idx: device index * @options: options for this console * * The last preferred console added will be used for kernel messages * and stdin/out/err for init. Normally this is used by console_setup * above to handle user-supplied console arguments; however it can also * be used by arch-specific code either to override the user or more * commonly to provide a default console (ie from PROM variables) when * the user has not supplied one. */ int add_preferred_console(char *name, int idx, char *options) { return __add_preferred_console(name, idx, options, NULL); } bool console_suspend_enabled = true; EXPORT_SYMBOL(console_suspend_enabled); static int __init console_suspend_disable(char *str) { console_suspend_enabled = false; return 1; } __setup("no_console_suspend", console_suspend_disable); module_param_named(console_suspend, console_suspend_enabled, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(console_suspend, "suspend console during suspend" " and hibernate operations"); /** * suspend_console - suspend the console subsystem * * This disables printk() while we go into suspend states */ void suspend_console(void) { if (!console_suspend_enabled) return; pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); console_lock(); console_suspended = 1; up_console_sem(); } void resume_console(void) { if (!console_suspend_enabled) return; down_console_sem(); console_suspended = 0; console_unlock(); } /** * console_cpu_notify - print deferred console messages after CPU hotplug * @cpu: unused * * If printk() is called from a CPU that is not online yet, the messages * will be printed on the console only if there are CON_ANYTIME consoles. * This function is called when a new CPU comes online (or fails to come * up) or goes offline. */ static int console_cpu_notify(unsigned int cpu) { if (!cpuhp_tasks_frozen) { /* If trylock fails, someone else is doing the printing */ if (console_trylock()) console_unlock(); } return 0; } /** * console_lock - lock the console system for exclusive use. * * Acquires a lock which guarantees that the caller has * exclusive access to the console system and the console_drivers list. * * Can sleep, returns nothing. */ void console_lock(void) { might_sleep(); down_console_sem(); if (console_suspended) return; console_locked = 1; console_may_schedule = 1; } EXPORT_SYMBOL(console_lock); /** * console_trylock - try to lock the console system for exclusive use. * * Try to acquire a lock which guarantees that the caller has exclusive * access to the console system and the console_drivers list. * * returns 1 on success, and 0 on failure to acquire the lock. */ int console_trylock(void) { if (down_trylock_console_sem()) return 0; if (console_suspended) { up_console_sem(); return 0; } console_locked = 1; console_may_schedule = 0; return 1; } EXPORT_SYMBOL(console_trylock); int is_console_locked(void) { return console_locked; } EXPORT_SYMBOL(is_console_locked); /** * console_unlock - unlock the console system * * Releases the console_lock which the caller holds on the console system * and the console driver list. * * console_unlock(); may be called from any context. */ void console_unlock(void) { if (console_suspended) { up_console_sem(); return; } console_locked = 0; up_console_sem(); } EXPORT_SYMBOL(console_unlock); /** * console_conditional_schedule - yield the CPU if required * * If the console code is currently allowed to sleep, and * if this CPU should yield the CPU to another task, do * so here. * * Must be called within console_lock();. */ void __sched console_conditional_schedule(void) { if (console_may_schedule) cond_resched(); } EXPORT_SYMBOL(console_conditional_schedule); void console_unblank(void) { struct console *c; /* * console_unblank can no longer be called in interrupt context unless * oops_in_progress is set to 1.. */ if (oops_in_progress) { if (down_trylock_console_sem() != 0) return; } else console_lock(); console_locked = 1; console_may_schedule = 0; for_each_console(c) if ((c->flags & CON_ENABLED) && c->unblank) c->unblank(); console_unlock(); } /** * console_flush_on_panic - flush console content on panic * @mode: flush all messages in buffer or just the pending ones * * Immediately output all pending messages no matter what. */ void console_flush_on_panic(enum con_flush_mode mode) { /* * FIXME: This is currently a NOP. Emergency messages will have been * printed, but what about if write_atomic is not available on the * console? What if the printk kthread is still alive? */ } /* * Return the console tty driver structure and its associated index */ struct tty_driver *console_device(int *index) { struct console *c; struct tty_driver *driver = NULL; console_lock(); for_each_console(c) { if (!c->device) continue; driver = c->device(c, index); if (driver) break; } console_unlock(); return driver; } /* * Prevent further output on the passed console device so that (for example) * serial drivers can disable console output before suspending a port, and can * re-enable output afterwards. */ void console_stop(struct console *console) { console_lock(); console->flags &= ~CON_ENABLED; console_unlock(); } EXPORT_SYMBOL(console_stop); void console_start(struct console *console) { console_lock(); console->flags |= CON_ENABLED; console_unlock(); } EXPORT_SYMBOL(console_start); static int __read_mostly keep_bootcon; static int __init keep_bootcon_setup(char *str) { keep_bootcon = 1; pr_info("debug: skip boot console de-registration.\n"); return 0; } early_param("keep_bootcon", keep_bootcon_setup); /* * The console driver calls this routine during kernel initialization * to register the console printing procedure with printk() and to * print any messages that were printed by the kernel before the * console driver was initialized. * * This can happen pretty early during the boot process (because of * early_printk) - sometimes before setup_arch() completes - be careful * of what kernel features are used - they may not be initialised yet. * * There are two types of consoles - bootconsoles (early_printk) and * "real" consoles (everything which is not a bootconsole) which are * handled differently. * - Any number of bootconsoles can be registered at any time. * - As soon as a "real" console is registered, all bootconsoles * will be unregistered automatically. * - Once a "real" console is registered, any attempt to register a * bootconsoles will be rejected */ void register_console(struct console *newcon) { int i; struct console *bcon = NULL; struct console_cmdline *c; static bool has_preferred; if (console_drivers) for_each_console(bcon) if (WARN(bcon == newcon, "console '%s%d' already registered\n", bcon->name, bcon->index)) return; /* * before we register a new CON_BOOT console, make sure we don't * already have a valid console */ if (console_drivers && newcon->flags & CON_BOOT) { /* find the last or real console */ for_each_console(bcon) { if (!(bcon->flags & CON_BOOT)) { pr_info("Too late to register bootconsole %s%d\n", newcon->name, newcon->index); return; } } } if (console_drivers && console_drivers->flags & CON_BOOT) bcon = console_drivers; if (!has_preferred || bcon || !console_drivers) has_preferred = preferred_console >= 0; /* * See if we want to use this console driver. If we * didn't select a console we take the first one * that registers here. */ if (!has_preferred) { if (newcon->index < 0) newcon->index = 0; if (newcon->setup == NULL || newcon->setup(newcon, NULL) == 0) { newcon->flags |= CON_ENABLED; if (newcon->device) { newcon->flags |= CON_CONSDEV; has_preferred = true; } } } /* * See if this console matches one we selected on * the command line. */ for (i = 0, c = console_cmdline; i < MAX_CMDLINECONSOLES && c->name[0]; i++, c++) { if (!newcon->match || newcon->match(newcon, c->name, c->index, c->options) != 0) { /* default matching */ BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); if (strcmp(c->name, newcon->name) != 0) continue; if (newcon->index >= 0 && newcon->index != c->index) continue; if (newcon->index < 0) newcon->index = c->index; if (_braille_register_console(newcon, c)) return; if (newcon->setup && newcon->setup(newcon, c->options) != 0) break; } newcon->flags |= CON_ENABLED; if (i == preferred_console) { newcon->flags |= CON_CONSDEV; has_preferred = true; } break; } if (!(newcon->flags & CON_ENABLED)) return; /* * If we have a bootconsole, and are switching to a real console, * don't print everything out again, since when the boot console, and * the real console are the same physical device, it's annoying to * see the beginning boot messages twice */ if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) newcon->flags &= ~CON_PRINTBUFFER; /* * Put this console in the list - keep the * preferred driver at the head of the list. */ console_lock(); if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { newcon->next = console_drivers; console_drivers = newcon; if (newcon->next) newcon->next->flags &= ~CON_CONSDEV; } else { newcon->next = console_drivers->next; console_drivers->next = newcon; } if (newcon->flags & CON_EXTENDED) nr_ext_console_drivers++; console_unlock(); console_sysfs_notify(); /* * By unregistering the bootconsoles after we enable the real console * we get the "console xxx enabled" message on all the consoles - * boot consoles, real consoles, etc - this is to ensure that end * users know there might be something in the kernel's log buffer that * went to the bootconsole (that they do not see on the real console) * * This message is also important because it will trigger the * printk kthread to begin dumping the log buffer to the newly * registered console. */ pr_info("%sconsole [%s%d] enabled\n", (newcon->flags & CON_BOOT) ? "boot" : "" , newcon->name, newcon->index); if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && !keep_bootcon) { /* We need to iterate through all boot consoles, to make * sure we print everything out, before we unregister them. */ for_each_console(bcon) if (bcon->flags & CON_BOOT) unregister_console(bcon); } } EXPORT_SYMBOL(register_console); int unregister_console(struct console *console) { struct console *a, *b; int res; pr_info("%sconsole [%s%d] disabled\n", (console->flags & CON_BOOT) ? "boot" : "" , console->name, console->index); res = _braille_unregister_console(console); if (res) return res; res = 1; console_lock(); if (console_drivers == console) { console_drivers=console->next; res = 0; } else if (console_drivers) { for (a=console_drivers->next, b=console_drivers ; a; b=a, a=b->next) { if (a == console) { b->next = a->next; res = 0; break; } } } if (!res && (console->flags & CON_EXTENDED)) nr_ext_console_drivers--; /* * If this isn't the last console and it has CON_CONSDEV set, we * need to set it on the next preferred console. */ if (console_drivers != NULL && console->flags & CON_CONSDEV) console_drivers->flags |= CON_CONSDEV; console->flags &= ~CON_ENABLED; console_unlock(); console_sysfs_notify(); return res; } EXPORT_SYMBOL(unregister_console); /* * Initialize the console device. This is called *early*, so * we can't necessarily depend on lots of kernel help here. * Just do some early initializations, and do the complex setup * later. */ void __init console_init(void) { int ret; initcall_t call; initcall_entry_t *ce; /* Setup the default TTY line discipline. */ n_tty_init(); /* * set up the console device so that later boot sequences can * inform about problems etc.. */ ce = __con_initcall_start; trace_initcall_level("console"); while (ce < __con_initcall_end) { call = initcall_from_entry(ce); trace_initcall_start(call); ret = call(); trace_initcall_finish(call, ret); ce++; } } /* * Some boot consoles access data that is in the init section and which will * be discarded after the initcalls have been run. To make sure that no code * will access this data, unregister the boot consoles in a late initcall. * * If for some reason, such as deferred probe or the driver being a loadable * module, the real console hasn't registered yet at this point, there will * be a brief interval in which no messages are logged to the console, which * makes it difficult to diagnose problems that occur during this time. * * To mitigate this problem somewhat, only unregister consoles whose memory * intersects with the init section. Note that all other boot consoles will * get unregistred when the real preferred console is registered. */ static int __init printk_late_init(void) { struct console *con; int ret; for_each_console(con) { if (!(con->flags & CON_BOOT)) continue; /* Check addresses that might be used for enabled consoles. */ if (init_section_intersects(con, sizeof(*con)) || init_section_contains(con->write, 0) || init_section_contains(con->read, 0) || init_section_contains(con->device, 0) || init_section_contains(con->unblank, 0) || init_section_contains(con->data, 0)) { /* * Please, consider moving the reported consoles out * of the init section. */ pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", con->name, con->index); unregister_console(con); } } ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, console_cpu_notify); WARN_ON(ret < 0); ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", console_cpu_notify, NULL); WARN_ON(ret < 0); return 0; } late_initcall(printk_late_init); #if defined CONFIG_PRINTK static int printk_kthread_func(void *data) { struct prb_iterator iter; struct printk_log *msg; size_t ext_len; char *ext_text; u64 master_seq; size_t len; char *text; char *buf; int ret; ext_text = kmalloc(CONSOLE_EXT_LOG_MAX, GFP_KERNEL); text = kmalloc(PRINTK_SPRINT_MAX, GFP_KERNEL); buf = kmalloc(PRINTK_RECORD_MAX, GFP_KERNEL); if (!ext_text || !text || !buf) return -1; prb_iter_init(&iter, &printk_rb, NULL); /* the printk kthread never exits */ for (;;) { ret = prb_iter_wait_next(&iter, buf, PRINTK_RECORD_MAX, &master_seq); if (ret == -ERESTARTSYS) { continue; } else if (ret < 0) { /* iterator invalid, start over */ prb_iter_init(&iter, &printk_rb, NULL); continue; } msg = (struct printk_log *)buf; format_text(msg, master_seq, ext_text, &ext_len, text, &len, printk_time); console_lock(); call_console_drivers(master_seq, ext_text, ext_len, text, len, msg->level, msg->facility); if (len > 0 || ext_len > 0) printk_delay(msg->level); console_unlock(); } kfree(ext_text); kfree(text); kfree(buf); return 0; } static int __init init_printk_kthread(void) { struct task_struct *thread; thread = kthread_run(printk_kthread_func, NULL, "printk"); if (IS_ERR(thread)) { pr_err("printk: unable to create printing thread\n"); return PTR_ERR(thread); } return 0; } late_initcall(init_printk_kthread); static int vprintk_deferred(const char *fmt, va_list args) { return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); } int printk_deferred(const char *fmt, ...) { va_list args; int r; va_start(args, fmt); r = vprintk_deferred(fmt, args); va_end(args); return r; } /* * printk rate limiting, lifted from the networking subsystem. * * This enforces a rate limit: not more than 10 kernel messages * every 5s to make a denial-of-service attack impossible. */ DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); int __printk_ratelimit(const char *func) { return ___ratelimit(&printk_ratelimit_state, func); } EXPORT_SYMBOL(__printk_ratelimit); /** * printk_timed_ratelimit - caller-controlled printk ratelimiting * @caller_jiffies: pointer to caller's state * @interval_msecs: minimum interval between prints * * printk_timed_ratelimit() returns true if more than @interval_msecs * milliseconds have elapsed since the last time printk_timed_ratelimit() * returned true. */ bool printk_timed_ratelimit(unsigned long *caller_jiffies, unsigned int interval_msecs) { unsigned long elapsed = jiffies - *caller_jiffies; if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) return false; *caller_jiffies = jiffies; return true; } EXPORT_SYMBOL(printk_timed_ratelimit); static DEFINE_SPINLOCK(dump_list_lock); static LIST_HEAD(dump_list); /** * kmsg_dump_register - register a kernel log dumper. * @dumper: pointer to the kmsg_dumper structure * * Adds a kernel log dumper to the system. The dump callback in the * structure will be called when the kernel oopses or panics and must be * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. */ int kmsg_dump_register(struct kmsg_dumper *dumper) { unsigned long flags; int err = -EBUSY; /* The dump callback needs to be set */ if (!dumper->dump) return -EINVAL; spin_lock_irqsave(&dump_list_lock, flags); /* Don't allow registering multiple times */ if (!dumper->registered) { dumper->registered = 1; list_add_tail_rcu(&dumper->list, &dump_list); err = 0; } spin_unlock_irqrestore(&dump_list_lock, flags); return err; } EXPORT_SYMBOL_GPL(kmsg_dump_register); /** * kmsg_dump_unregister - unregister a kmsg dumper. * @dumper: pointer to the kmsg_dumper structure * * Removes a dump device from the system. Returns zero on success and * %-EINVAL otherwise. */ int kmsg_dump_unregister(struct kmsg_dumper *dumper) { unsigned long flags; int err = -EINVAL; spin_lock_irqsave(&dump_list_lock, flags); if (dumper->registered) { dumper->registered = 0; list_del_rcu(&dumper->list); err = 0; } spin_unlock_irqrestore(&dump_list_lock, flags); synchronize_rcu(); return err; } EXPORT_SYMBOL_GPL(kmsg_dump_unregister); static bool always_kmsg_dump; module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); /** * kmsg_dump - dump kernel log to kernel message dumpers. * @reason: the reason (oops, panic etc) for dumping * * Call each of the registered dumper's dump() callback, which can * retrieve the kmsg records with kmsg_dump_get_line() or * kmsg_dump_get_buffer(). */ void kmsg_dump(enum kmsg_dump_reason reason) { struct kmsg_dumper dumper_local; struct kmsg_dumper *dumper; if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) return; rcu_read_lock(); list_for_each_entry_rcu(dumper, &dump_list, list) { if (dumper->max_reason && reason > dumper->max_reason) continue; /* * use a local copy to avoid modifying the * iterator used by any other cpus/contexts */ memcpy(&dumper_local, dumper, sizeof(dumper_local)); /* initialize iterator with data about the stored records */ dumper_local.active = true; kmsg_dump_rewind(&dumper_local); /* invoke dumper which will iterate over records */ dumper_local.dump(&dumper_local, reason); } rcu_read_unlock(); } /** * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) * @dumper: registered kmsg dumper * @syslog: include the "<4>" prefixes * @line: buffer to copy the line to * @size: maximum size of the buffer * @len: length of line placed into buffer * * Start at the beginning of the kmsg buffer, with the oldest kmsg * record, and copy one record into the provided buffer. * * Consecutive calls will return the next available record moving * towards the end of the buffer with the youngest messages. * * A return value of FALSE indicates that there are no more records to * read. * * The function is similar to kmsg_dump_get_line(), but grabs no locks. */ bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, char *line, size_t size, size_t *len) { struct prb_iterator iter; struct printk_log *msg; struct prb_handle h; bool cont = false; char *msgbuf; char *rbuf; size_t l; u64 seq; int ret; if (!dumper->active) return cont; rbuf = prb_reserve(&h, &sprint_rb, PRINTK_RECORD_MAX); if (!rbuf) return cont; msgbuf = rbuf; retry: for (;;) { prb_iter_init(&iter, &printk_rb, &seq); if (dumper->line_seq == seq) { /* already where we want to be */ break; } else if (dumper->line_seq < seq) { /* messages are gone, move to first available one */ dumper->line_seq = seq; break; } ret = prb_iter_seek(&iter, dumper->line_seq); if (ret > 0) { /* seeked to line_seq */ break; } else if (ret == 0) { /* * The end of the list was hit without ever seeing * line_seq. Reset it to the beginning of the list. */ prb_iter_init(&iter, &printk_rb, &dumper->line_seq); break; } /* iterator invalid, start over */ } ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &dumper->line_seq); if (ret == 0) goto out; else if (ret < 0) goto retry; msg = (struct printk_log *)msgbuf; l = msg_print_text(msg, syslog, printk_time, line, size); if (len) *len = l; cont = true; out: prb_commit(&h); return cont; } /** * kmsg_dump_get_line - retrieve one kmsg log line * @dumper: registered kmsg dumper * @syslog: include the "<4>" prefixes * @line: buffer to copy the line to * @size: maximum size of the buffer * @len: length of line placed into buffer * * Start at the beginning of the kmsg buffer, with the oldest kmsg * record, and copy one record into the provided buffer. * * Consecutive calls will return the next available record moving * towards the end of the buffer with the youngest messages. * * A return value of FALSE indicates that there are no more records to * read. */ bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, char *line, size_t size, size_t *len) { bool ret; ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); return ret; } EXPORT_SYMBOL_GPL(kmsg_dump_get_line); /** * kmsg_dump_get_buffer - copy kmsg log lines * @dumper: registered kmsg dumper * @syslog: include the "<4>" prefixes * @buf: buffer to copy the line to * @size: maximum size of the buffer * @len: length of line placed into buffer * * Start at the end of the kmsg buffer and fill the provided buffer * with as many of the the *youngest* kmsg records that fit into it. * If the buffer is large enough, all available kmsg records will be * copied with a single call. * * Consecutive calls will fill the buffer with the next block of * available older records, not including the earlier retrieved ones. * * A return value of FALSE indicates that there are no more records to * read. */ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, char *buf, size_t size, size_t *len) { struct prb_iterator iter; bool time = printk_time; struct printk_log *msg; u64 new_end_seq = 0; struct prb_handle h; bool cont = false; char *msgbuf; u64 end_seq; int textlen; u64 seq = 0; char *rbuf; int l = 0; int ret; if (!dumper->active) return cont; rbuf = prb_reserve(&h, &sprint_rb, PRINTK_RECORD_MAX); if (!rbuf) return cont; msgbuf = rbuf; prb_iter_init(&iter, &printk_rb, NULL); /* * seek to the start record, which is set/modified * by kmsg_dump_get_line_nolock() */ ret = prb_iter_seek(&iter, dumper->line_seq); if (ret <= 0) prb_iter_init(&iter, &printk_rb, &seq); /* work with a local end seq to have a constant value */ end_seq = dumper->buffer_end_seq; if (!end_seq) { /* initialize end seq to "infinity" */ end_seq = -1; dumper->buffer_end_seq = end_seq; } retry: if (seq >= end_seq) goto out; /* count the total bytes after seq */ textlen = count_remaining(&iter, end_seq, msgbuf, PRINTK_RECORD_MAX, 0, time); /* move iter forward until length fits into the buffer */ while (textlen > size) { ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &seq); if (ret == 0) { break; } else if (ret < 0 || seq >= end_seq) { prb_iter_init(&iter, &printk_rb, &seq); goto retry; } msg = (struct printk_log *)msgbuf; textlen -= msg_print_text(msg, true, time, NULL, 0); } /* save end seq for the next interation */ new_end_seq = seq + 1; /* copy messages to buffer */ while (l < size) { ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &seq); if (ret == 0) { break; } else if (ret < 0) { /* * iterator (and thus also the start position) * invalid, start over from beginning of list */ prb_iter_init(&iter, &printk_rb, NULL); continue; } if (seq >= end_seq) break; msg = (struct printk_log *)msgbuf; textlen = msg_print_text(msg, syslog, time, buf + l, size - l); if (textlen > 0) l += textlen; cont = true; } if (cont && len) *len = l; out: prb_commit(&h); if (new_end_seq) dumper->buffer_end_seq = new_end_seq; return cont; } EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); /** * kmsg_dump_rewind_nolock - reset the interator (unlocked version) * @dumper: registered kmsg dumper * * Reset the dumper's iterator so that kmsg_dump_get_line() and * kmsg_dump_get_buffer() can be called again and used multiple * times within the same dumper.dump() callback. * * The function is similar to kmsg_dump_rewind(), but grabs no locks. */ void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) { dumper->line_seq = 0; dumper->buffer_end_seq = 0; } /** * kmsg_dump_rewind - reset the interator * @dumper: registered kmsg dumper * * Reset the dumper's iterator so that kmsg_dump_get_line() and * kmsg_dump_get_buffer() can be called again and used multiple * times within the same dumper.dump() callback. */ void kmsg_dump_rewind(struct kmsg_dumper *dumper) { kmsg_dump_rewind_nolock(dumper); } EXPORT_SYMBOL_GPL(kmsg_dump_rewind); static bool console_can_emergency(int level) { struct console *con; for_each_console(con) { if (!(con->flags & CON_ENABLED)) continue; if (con->write_atomic && level < emergency_console_loglevel) return true; if (con->write && (con->flags & CON_BOOT)) return true; } return false; } static void call_emergency_console_drivers(int level, const char *text, size_t text_len) { struct console *con; for_each_console(con) { if (!(con->flags & CON_ENABLED)) continue; if (con->write_atomic && level < emergency_console_loglevel) { con->write_atomic(con, text, text_len); continue; } if (con->write && (con->flags & CON_BOOT)) { con->write(con, text, text_len); continue; } } } static void printk_emergency(char *buffer, int level, u64 ts_nsec, u16 cpu, char *text, u16 text_len) { struct printk_log msg; size_t prefix_len; if (!console_can_emergency(level)) return; msg.level = level; msg.ts_nsec = ts_nsec; msg.cpu = cpu; msg.facility = 0; /* "text" must have PREFIX_MAX preceding bytes available */ prefix_len = print_prefix(&msg, console_msg_format & MSG_FORMAT_SYSLOG, printk_time, buffer); /* move the prefix forward to the beginning of the message text */ text -= prefix_len; memmove(text, buffer, prefix_len); text_len += prefix_len; text[text_len++] = '\n'; call_emergency_console_drivers(level, text, text_len); touch_softlockup_watchdog_sync(); clocksource_touch_watchdog(); rcu_cpu_stall_reset(); touch_nmi_watchdog(); printk_delay(level); } #endif void console_atomic_lock(unsigned int *flags) { prb_lock(&printk_cpulock, flags); } EXPORT_SYMBOL(console_atomic_lock); void console_atomic_unlock(unsigned int flags) { prb_unlock(&printk_cpulock, flags); } EXPORT_SYMBOL(console_atomic_unlock);