Make it easier to break up printk into bite-sized chunks.
Remove printk path/filename from comment.
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
<sect1><title>Kernel utility functions</title>
!Iinclude/linux/kernel.h
-!Ekernel/printk.c
+!Ekernel/printk/printk.c
!Ekernel/panic.c
!Ekernel/sys.c
!Ekernel/rcupdate.c
# Makefile for the linux kernel.
#
-obj-y = fork.o exec_domain.o panic.o printk.o \
+obj-y = fork.o exec_domain.o panic.o \
cpu.o exit.o itimer.o time.o softirq.o resource.o \
sysctl.o sysctl_binary.o capability.o ptrace.o timer.o user.o \
signal.o sys.o kmod.o workqueue.o pid.o task_work.o \
obj-y += sched/
obj-y += power/
+obj-y += printk/
obj-y += cpu/
obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o
+++ /dev/null
-/*
- * 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
- */
-
-#include <linux/kernel.h>
-#include <linux/mm.h>
-#include <linux/tty.h>
-#include <linux/tty_driver.h>
-#include <linux/console.h>
-#include <linux/init.h>
-#include <linux/jiffies.h>
-#include <linux/nmi.h>
-#include <linux/module.h>
-#include <linux/moduleparam.h>
-#include <linux/interrupt.h> /* For in_interrupt() */
-#include <linux/delay.h>
-#include <linux/smp.h>
-#include <linux/security.h>
-#include <linux/bootmem.h>
-#include <linux/memblock.h>
-#include <linux/aio.h>
-#include <linux/syscalls.h>
-#include <linux/kexec.h>
-#include <linux/kdb.h>
-#include <linux/ratelimit.h>
-#include <linux/kmsg_dump.h>
-#include <linux/syslog.h>
-#include <linux/cpu.h>
-#include <linux/notifier.h>
-#include <linux/rculist.h>
-#include <linux/poll.h>
-#include <linux/irq_work.h>
-#include <linux/utsname.h>
-
-#include <asm/uaccess.h>
-
-#define CREATE_TRACE_POINTS
-#include <trace/events/printk.h>
-
-/* printk's without a loglevel use this.. */
-#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
-
-/* We show everything that is MORE important than this.. */
-#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
-#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
-
-int console_printk[4] = {
- DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
- DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
- MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
- DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
-};
-
-/*
- * 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);
-
-#ifdef CONFIG_LOCKDEP
-static struct lockdep_map console_lock_dep_map = {
- .name = "console_lock"
-};
-#endif
-
-/*
- * 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 are racing, but it helps tracking those weird code
- * path in the console code where we end up in places I want
- * locked without the console sempahore held
- */
-static int console_locked, console_suspended;
-
-/*
- * If exclusive_console is non-NULL then only this console is to be printed to.
- */
-static struct console *exclusive_console;
-
-/*
- * Array of consoles built from command line options (console=)
- */
-struct console_cmdline
-{
- char name[8]; /* Name of the driver */
- int index; /* Minor dev. to use */
- char *options; /* Options for the driver */
-#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
- char *brl_options; /* Options for braille driver */
-#endif
-};
-
-#define MAX_CMDLINECONSOLES 8
-
-static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
-static int selected_console = -1;
-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;
-
-/*
- * 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 both 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 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:
- * "level,sequnum,timestamp;<message text>\n"
- *
- * 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.
- *
- * Users of the export format should ignore possible additional values
- * separated by ',', and find the message after the ';' character.
- */
-
-enum log_flags {
- LOG_NOCONS = 1, /* already flushed, do not print to console */
- LOG_NEWLINE = 2, /* text ended with a newline */
- LOG_PREFIX = 4, /* text started with a prefix */
- LOG_CONT = 8, /* text is a fragment of a continuation line */
-};
-
-struct log {
- u64 ts_nsec; /* timestamp in nanoseconds */
- 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 */
-};
-
-/*
- * The logbuf_lock protects kmsg buffer, indices, counters. It is also
- * used in interesting ways to provide interlocking in console_unlock();
- */
-static DEFINE_RAW_SPINLOCK(logbuf_lock);
-
-#ifdef CONFIG_PRINTK
-DECLARE_WAIT_QUEUE_HEAD(log_wait);
-/* the next printk record to read by syslog(READ) or /proc/kmsg */
-static u64 syslog_seq;
-static u32 syslog_idx;
-static enum log_flags syslog_prev;
-static size_t syslog_partial;
-
-/* index and sequence number of the first record stored in the buffer */
-static u64 log_first_seq;
-static u32 log_first_idx;
-
-/* index and sequence number of the next record to store in the buffer */
-static u64 log_next_seq;
-static u32 log_next_idx;
-
-/* the next printk record to write to the console */
-static u64 console_seq;
-static u32 console_idx;
-static enum log_flags console_prev;
-
-/* the next printk record to read after the last 'clear' command */
-static u64 clear_seq;
-static u32 clear_idx;
-
-#define PREFIX_MAX 32
-#define LOG_LINE_MAX 1024 - PREFIX_MAX
-
-/* record buffer */
-#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
-#define LOG_ALIGN 4
-#else
-#define LOG_ALIGN __alignof__(struct log)
-#endif
-#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
-static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
-static char *log_buf = __log_buf;
-static u32 log_buf_len = __LOG_BUF_LEN;
-
-/* cpu currently holding logbuf_lock */
-static volatile unsigned int logbuf_cpu = UINT_MAX;
-
-/* human readable text of the record */
-static char *log_text(const struct log *msg)
-{
- return (char *)msg + sizeof(struct log);
-}
-
-/* optional key/value pair dictionary attached to the record */
-static char *log_dict(const struct log *msg)
-{
- return (char *)msg + sizeof(struct log) + msg->text_len;
-}
-
-/* get record by index; idx must point to valid msg */
-static struct log *log_from_idx(u32 idx)
-{
- struct log *msg = (struct log *)(log_buf + idx);
-
- /*
- * A length == 0 record is the end of buffer marker. Wrap around and
- * read the message at the start of the buffer.
- */
- if (!msg->len)
- return (struct log *)log_buf;
- return msg;
-}
-
-/* get next record; idx must point to valid msg */
-static u32 log_next(u32 idx)
-{
- struct log *msg = (struct log *)(log_buf + idx);
-
- /* length == 0 indicates the end of the buffer; wrap */
- /*
- * A length == 0 record is the end of buffer marker. Wrap around and
- * read the message at the start of the buffer as *this* one, and
- * return the one after that.
- */
- if (!msg->len) {
- msg = (struct log *)log_buf;
- return msg->len;
- }
- return idx + msg->len;
-}
-
-/* insert record into the buffer, discard old ones, update heads */
-static void log_store(int facility, int level,
- enum log_flags flags, u64 ts_nsec,
- const char *dict, u16 dict_len,
- const char *text, u16 text_len)
-{
- struct log *msg;
- u32 size, pad_len;
-
- /* number of '\0' padding bytes to next message */
- size = sizeof(struct log) + text_len + dict_len;
- pad_len = (-size) & (LOG_ALIGN - 1);
- size += pad_len;
-
- while (log_first_seq < log_next_seq) {
- u32 free;
-
- if (log_next_idx > log_first_idx)
- free = max(log_buf_len - log_next_idx, log_first_idx);
- else
- free = log_first_idx - log_next_idx;
-
- if (free > size + sizeof(struct log))
- break;
-
- /* drop old messages until we have enough contiuous space */
- log_first_idx = log_next(log_first_idx);
- log_first_seq++;
- }
-
- if (log_next_idx + size + sizeof(struct log) >= log_buf_len) {
- /*
- * This message + an additional empty header does not fit
- * at the end of the buffer. Add an empty header with len == 0
- * to signify a wrap around.
- */
- memset(log_buf + log_next_idx, 0, sizeof(struct log));
- log_next_idx = 0;
- }
-
- /* fill message */
- msg = (struct log *)(log_buf + log_next_idx);
- 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;
- if (ts_nsec > 0)
- msg->ts_nsec = ts_nsec;
- else
- msg->ts_nsec = local_clock();
- memset(log_dict(msg) + dict_len, 0, pad_len);
- msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
-
- /* insert message */
- log_next_idx += msg->len;
- log_next_seq++;
-}
-
-#ifdef CONFIG_SECURITY_DMESG_RESTRICT
-int dmesg_restrict = 1;
-#else
-int dmesg_restrict;
-#endif
-
-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, bool from_file)
-{
- /*
- * If this is from /proc/kmsg and we've already opened it, then we've
- * already done the capabilities checks at open time.
- */
- if (from_file && type != SYSLOG_ACTION_OPEN)
- return 0;
-
- if (syslog_action_restricted(type)) {
- if (capable(CAP_SYSLOG))
- return 0;
- /*
- * 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));
- return 0;
- }
- return -EPERM;
- }
- return security_syslog(type);
-}
-
-
-/* /dev/kmsg - userspace message inject/listen interface */
-struct devkmsg_user {
- u64 seq;
- u32 idx;
- enum log_flags prev;
- struct mutex lock;
- char buf[8192];
-};
-
-static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
- unsigned long count, loff_t pos)
-{
- char *buf, *line;
- int i;
- int level = default_message_loglevel;
- int facility = 1; /* LOG_USER */
- size_t len = iov_length(iv, count);
- ssize_t ret = len;
-
- if (len > LOG_LINE_MAX)
- return -EINVAL;
- buf = kmalloc(len+1, GFP_KERNEL);
- if (buf == NULL)
- return -ENOMEM;
-
- line = buf;
- for (i = 0; i < count; i++) {
- if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
- ret = -EFAULT;
- goto out;
- }
- line += iv[i].iov_len;
- }
-
- /*
- * 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;
-
- i = simple_strtoul(line+1, &endp, 10);
- if (endp && endp[0] == '>') {
- level = i & 7;
- if (i >> 3)
- facility = i >> 3;
- endp++;
- len -= endp - line;
- line = endp;
- }
- }
- line[len] = '\0';
-
- printk_emit(facility, level, NULL, 0, "%s", line);
-out:
- 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 log *msg;
- u64 ts_usec;
- size_t i;
- char cont = '-';
- size_t len;
- ssize_t ret;
-
- if (!user)
- return -EBADF;
-
- ret = mutex_lock_interruptible(&user->lock);
- if (ret)
- return ret;
- raw_spin_lock_irq(&logbuf_lock);
- while (user->seq == log_next_seq) {
- if (file->f_flags & O_NONBLOCK) {
- ret = -EAGAIN;
- raw_spin_unlock_irq(&logbuf_lock);
- goto out;
- }
-
- raw_spin_unlock_irq(&logbuf_lock);
- ret = wait_event_interruptible(log_wait,
- user->seq != log_next_seq);
- if (ret)
- goto out;
- raw_spin_lock_irq(&logbuf_lock);
- }
-
- if (user->seq < log_first_seq) {
- /* our last seen message is gone, return error and reset */
- user->idx = log_first_idx;
- user->seq = log_first_seq;
- ret = -EPIPE;
- raw_spin_unlock_irq(&logbuf_lock);
- goto out;
- }
-
- msg = log_from_idx(user->idx);
- ts_usec = msg->ts_nsec;
- do_div(ts_usec, 1000);
-
- /*
- * If we couldn't merge continuation line fragments during the print,
- * export the stored flags to allow an optional external merge of the
- * records. Merging the records isn't always neccessarily correct, like
- * when we hit a race during printing. In most cases though, it produces
- * better readable output. 'c' in the record flags mark the first
- * fragment of a line, '+' the following.
- */
- if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
- cont = 'c';
- else if ((msg->flags & LOG_CONT) ||
- ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
- cont = '+';
-
- len = sprintf(user->buf, "%u,%llu,%llu,%c;",
- (msg->facility << 3) | msg->level,
- user->seq, ts_usec, cont);
- user->prev = msg->flags;
-
- /* escape non-printable characters */
- for (i = 0; i < msg->text_len; i++) {
- unsigned char c = log_text(msg)[i];
-
- if (c < ' ' || c >= 127 || c == '\\')
- len += sprintf(user->buf + len, "\\x%02x", c);
- else
- user->buf[len++] = c;
- }
- user->buf[len++] = '\n';
-
- if (msg->dict_len) {
- bool line = true;
-
- for (i = 0; i < msg->dict_len; i++) {
- unsigned char c = log_dict(msg)[i];
-
- if (line) {
- user->buf[len++] = ' ';
- line = false;
- }
-
- if (c == '\0') {
- user->buf[len++] = '\n';
- line = true;
- continue;
- }
-
- if (c < ' ' || c >= 127 || c == '\\') {
- len += sprintf(user->buf + len, "\\x%02x", c);
- continue;
- }
-
- user->buf[len++] = c;
- }
- user->buf[len++] = '\n';
- }
-
- user->idx = log_next(user->idx);
- user->seq++;
- raw_spin_unlock_irq(&logbuf_lock);
-
- if (len > count) {
- ret = -EINVAL;
- goto out;
- }
-
- if (copy_to_user(buf, user->buf, len)) {
- ret = -EFAULT;
- goto out;
- }
- ret = len;
-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 = 0;
-
- if (!user)
- return -EBADF;
- if (offset)
- return -ESPIPE;
-
- raw_spin_lock_irq(&logbuf_lock);
- switch (whence) {
- case SEEK_SET:
- /* the first record */
- user->idx = log_first_idx;
- user->seq = log_first_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.
- */
- user->idx = clear_idx;
- user->seq = clear_seq;
- break;
- case SEEK_END:
- /* after the last record */
- user->idx = log_next_idx;
- user->seq = log_next_seq;
- break;
- default:
- ret = -EINVAL;
- }
- raw_spin_unlock_irq(&logbuf_lock);
- return ret;
-}
-
-static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
-{
- struct devkmsg_user *user = file->private_data;
- int ret = 0;
-
- if (!user)
- return POLLERR|POLLNVAL;
-
- poll_wait(file, &log_wait, wait);
-
- raw_spin_lock_irq(&logbuf_lock);
- if (user->seq < log_next_seq) {
- /* return error when data has vanished underneath us */
- if (user->seq < log_first_seq)
- ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
- else
- ret = POLLIN|POLLRDNORM;
- }
- raw_spin_unlock_irq(&logbuf_lock);
-
- return ret;
-}
-
-static int devkmsg_open(struct inode *inode, struct file *file)
-{
- struct devkmsg_user *user;
- int err;
-
- /* write-only does not need any file context */
- if ((file->f_flags & O_ACCMODE) == O_WRONLY)
- return 0;
-
- 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;
-
- mutex_init(&user->lock);
-
- raw_spin_lock_irq(&logbuf_lock);
- user->idx = log_first_idx;
- user->seq = log_first_seq;
- raw_spin_unlock_irq(&logbuf_lock);
-
- 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;
-
- mutex_destroy(&user->lock);
- kfree(user);
- return 0;
-}
-
-const struct file_operations kmsg_fops = {
- .open = devkmsg_open,
- .read = devkmsg_read,
- .aio_write = devkmsg_writev,
- .llseek = devkmsg_llseek,
- .poll = devkmsg_poll,
- .release = devkmsg_release,
-};
-
-#ifdef CONFIG_KEXEC
-/*
- * This appends the listed symbols to /proc/vmcoreinfo
- *
- * /proc/vmcoreinfo is used by various utiilties, 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_kexec_setup(void)
-{
- VMCOREINFO_SYMBOL(log_buf);
- VMCOREINFO_SYMBOL(log_buf_len);
- VMCOREINFO_SYMBOL(log_first_idx);
- VMCOREINFO_SYMBOL(log_next_idx);
- /*
- * Export struct log size and field offsets. User space tools can
- * parse it and detect any changes to structure down the line.
- */
- VMCOREINFO_STRUCT_SIZE(log);
- VMCOREINFO_OFFSET(log, ts_nsec);
- VMCOREINFO_OFFSET(log, len);
- VMCOREINFO_OFFSET(log, text_len);
- VMCOREINFO_OFFSET(log, dict_len);
-}
-#endif
-
-/* requested log_buf_len from kernel cmdline */
-static unsigned long __initdata new_log_buf_len;
-
-/* save requested log_buf_len since it's too early to process it */
-static int __init log_buf_len_setup(char *str)
-{
- unsigned size = memparse(str, &str);
-
- if (size)
- size = roundup_pow_of_two(size);
- if (size > log_buf_len)
- new_log_buf_len = size;
-
- return 0;
-}
-early_param("log_buf_len", log_buf_len_setup);
-
-void __init setup_log_buf(int early)
-{
- unsigned long flags;
- char *new_log_buf;
- int free;
-
- if (!new_log_buf_len)
- return;
-
- if (early) {
- unsigned long mem;
-
- mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
- if (!mem)
- return;
- new_log_buf = __va(mem);
- } else {
- new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
- }
-
- if (unlikely(!new_log_buf)) {
- pr_err("log_buf_len: %ld bytes not available\n",
- new_log_buf_len);
- return;
- }
-
- raw_spin_lock_irqsave(&logbuf_lock, 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);
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-
- pr_info("log_buf_len: %d\n", log_buf_len);
- pr_info("early log buf free: %d(%d%%)\n",
- free, (free * 100) / __LOG_BUF_LEN);
-}
-
-static bool __read_mostly ignore_loglevel;
-
-static int __init ignore_loglevel_setup(char *str)
-{
- ignore_loglevel = 1;
- printk(KERN_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, to"
- "print all kernel messages to the console.");
-
-#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 1;
-}
-__setup("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_BOOTING)
- || (level >= console_loglevel && !ignore_loglevel)) {
- 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
-
-#if defined(CONFIG_PRINTK_TIME)
-static bool printk_time = 1;
-#else
-static bool printk_time;
-#endif
-module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
-
-static size_t print_time(u64 ts, char *buf)
-{
- unsigned long rem_nsec;
-
- if (!printk_time)
- return 0;
-
- rem_nsec = do_div(ts, 1000000000);
-
- if (!buf)
- return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
-
- return sprintf(buf, "[%5lu.%06lu] ",
- (unsigned long)ts, rem_nsec / 1000);
-}
-
-static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
-{
- size_t len = 0;
- unsigned int prefix = (msg->facility << 3) | msg->level;
-
- if (syslog) {
- if (buf) {
- len += sprintf(buf, "<%u>", prefix);
- } else {
- len += 3;
- if (prefix > 999)
- len += 3;
- else if (prefix > 99)
- len += 2;
- else if (prefix > 9)
- len++;
- }
- }
-
- len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
- return len;
-}
-
-static size_t msg_print_text(const struct log *msg, enum log_flags prev,
- bool syslog, char *buf, size_t size)
-{
- const char *text = log_text(msg);
- size_t text_size = msg->text_len;
- bool prefix = true;
- bool newline = true;
- size_t len = 0;
-
- if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
- prefix = false;
-
- if (msg->flags & LOG_CONT) {
- if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
- prefix = false;
-
- if (!(msg->flags & LOG_NEWLINE))
- newline = false;
- }
-
- 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 (print_prefix(msg, syslog, NULL) +
- text_len + 1 >= size - len)
- break;
-
- if (prefix)
- len += print_prefix(msg, syslog, buf + len);
- memcpy(buf + len, text, text_len);
- len += text_len;
- if (next || newline)
- buf[len++] = '\n';
- } else {
- /* SYSLOG_ACTION_* buffer size only calculation */
- if (prefix)
- len += print_prefix(msg, syslog, NULL);
- len += text_len;
- if (next || newline)
- len++;
- }
-
- prefix = true;
- text = next;
- } while (text);
-
- return len;
-}
-
-static int syslog_print(char __user *buf, int size)
-{
- char *text;
- struct log *msg;
- int len = 0;
-
- text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
- if (!text)
- return -ENOMEM;
-
- while (size > 0) {
- size_t n;
- size_t skip;
-
- raw_spin_lock_irq(&logbuf_lock);
- if (syslog_seq < log_first_seq) {
- /* messages are gone, move to first one */
- syslog_seq = log_first_seq;
- syslog_idx = log_first_idx;
- syslog_prev = 0;
- syslog_partial = 0;
- }
- if (syslog_seq == log_next_seq) {
- raw_spin_unlock_irq(&logbuf_lock);
- break;
- }
-
- skip = syslog_partial;
- msg = log_from_idx(syslog_idx);
- n = msg_print_text(msg, syslog_prev, true, text,
- LOG_LINE_MAX + PREFIX_MAX);
- if (n - syslog_partial <= size) {
- /* message fits into buffer, move forward */
- syslog_idx = log_next(syslog_idx);
- syslog_seq++;
- syslog_prev = msg->flags;
- n -= syslog_partial;
- syslog_partial = 0;
- } else if (!len){
- /* partial read(), remember position */
- n = size;
- syslog_partial += n;
- } else
- n = 0;
- raw_spin_unlock_irq(&logbuf_lock);
-
- if (!n)
- break;
-
- if (copy_to_user(buf, text + skip, n)) {
- if (!len)
- len = -EFAULT;
- break;
- }
-
- len += n;
- size -= n;
- buf += n;
- }
-
- kfree(text);
- return len;
-}
-
-static int syslog_print_all(char __user *buf, int size, bool clear)
-{
- char *text;
- int len = 0;
-
- text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
- if (!text)
- return -ENOMEM;
-
- raw_spin_lock_irq(&logbuf_lock);
- if (buf) {
- u64 next_seq;
- u64 seq;
- u32 idx;
- enum log_flags prev;
-
- if (clear_seq < log_first_seq) {
- /* messages are gone, move to first available one */
- clear_seq = log_first_seq;
- clear_idx = log_first_idx;
- }
-
- /*
- * Find first record that fits, including all following records,
- * into the user-provided buffer for this dump.
- */
- seq = clear_seq;
- idx = clear_idx;
- prev = 0;
- while (seq < log_next_seq) {
- struct log *msg = log_from_idx(idx);
-
- len += msg_print_text(msg, prev, true, NULL, 0);
- prev = msg->flags;
- idx = log_next(idx);
- seq++;
- }
-
- /* move first record forward until length fits into the buffer */
- seq = clear_seq;
- idx = clear_idx;
- prev = 0;
- while (len > size && seq < log_next_seq) {
- struct log *msg = log_from_idx(idx);
-
- len -= msg_print_text(msg, prev, true, NULL, 0);
- prev = msg->flags;
- idx = log_next(idx);
- seq++;
- }
-
- /* last message fitting into this dump */
- next_seq = log_next_seq;
-
- len = 0;
- prev = 0;
- while (len >= 0 && seq < next_seq) {
- struct log *msg = log_from_idx(idx);
- int textlen;
-
- textlen = msg_print_text(msg, prev, true, text,
- LOG_LINE_MAX + PREFIX_MAX);
- if (textlen < 0) {
- len = textlen;
- break;
- }
- idx = log_next(idx);
- seq++;
- prev = msg->flags;
-
- raw_spin_unlock_irq(&logbuf_lock);
- if (copy_to_user(buf + len, text, textlen))
- len = -EFAULT;
- else
- len += textlen;
- raw_spin_lock_irq(&logbuf_lock);
-
- if (seq < log_first_seq) {
- /* messages are gone, move to next one */
- seq = log_first_seq;
- idx = log_first_idx;
- prev = 0;
- }
- }
- }
-
- if (clear) {
- clear_seq = log_next_seq;
- clear_idx = log_next_idx;
- }
- raw_spin_unlock_irq(&logbuf_lock);
-
- kfree(text);
- return len;
-}
-
-int do_syslog(int type, char __user *buf, int len, bool from_file)
-{
- bool clear = false;
- static int saved_console_loglevel = -1;
- int error;
-
- error = check_syslog_permissions(type, from_file);
- if (error)
- goto out;
-
- error = security_syslog(type);
- 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 */
- error = -EINVAL;
- if (!buf || len < 0)
- goto out;
- error = 0;
- if (!len)
- goto out;
- if (!access_ok(VERIFY_WRITE, buf, len)) {
- error = -EFAULT;
- goto out;
- }
- error = wait_event_interruptible(log_wait,
- syslog_seq != log_next_seq);
- if (error)
- goto out;
- error = syslog_print(buf, len);
- break;
- /* Read/clear last kernel messages */
- case SYSLOG_ACTION_READ_CLEAR:
- clear = true;
- /* FALL THRU */
- /* Read last kernel messages */
- case SYSLOG_ACTION_READ_ALL:
- error = -EINVAL;
- if (!buf || len < 0)
- goto out;
- error = 0;
- if (!len)
- goto out;
- if (!access_ok(VERIFY_WRITE, buf, len)) {
- error = -EFAULT;
- goto out;
- }
- error = syslog_print_all(buf, len, clear);
- break;
- /* Clear ring buffer */
- case SYSLOG_ACTION_CLEAR:
- syslog_print_all(NULL, 0, true);
- break;
- /* Disable logging to console */
- case SYSLOG_ACTION_CONSOLE_OFF:
- if (saved_console_loglevel == -1)
- saved_console_loglevel = console_loglevel;
- console_loglevel = minimum_console_loglevel;
- break;
- /* Enable logging to console */
- case SYSLOG_ACTION_CONSOLE_ON:
- if (saved_console_loglevel != -1) {
- console_loglevel = saved_console_loglevel;
- saved_console_loglevel = -1;
- }
- break;
- /* Set level of messages printed to console */
- case SYSLOG_ACTION_CONSOLE_LEVEL:
- error = -EINVAL;
- if (len < 1 || len > 8)
- goto out;
- if (len < minimum_console_loglevel)
- len = minimum_console_loglevel;
- console_loglevel = len;
- /* Implicitly re-enable logging to console */
- saved_console_loglevel = -1;
- error = 0;
- break;
- /* Number of chars in the log buffer */
- case SYSLOG_ACTION_SIZE_UNREAD:
- raw_spin_lock_irq(&logbuf_lock);
- if (syslog_seq < log_first_seq) {
- /* messages are gone, move to first one */
- syslog_seq = log_first_seq;
- syslog_idx = log_first_idx;
- syslog_prev = 0;
- syslog_partial = 0;
- }
- if (from_file) {
- /*
- * Short-cut for poll(/"proc/kmsg") which simply checks
- * for pending data, not the size; return the count of
- * records, not the length.
- */
- error = log_next_idx - syslog_idx;
- } else {
- u64 seq = syslog_seq;
- u32 idx = syslog_idx;
- enum log_flags prev = syslog_prev;
-
- error = 0;
- while (seq < log_next_seq) {
- struct log *msg = log_from_idx(idx);
-
- error += msg_print_text(msg, prev, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- prev = msg->flags;
- }
- error -= syslog_partial;
- }
- raw_spin_unlock_irq(&logbuf_lock);
- break;
- /* Size of the log buffer */
- case SYSLOG_ACTION_SIZE_BUFFER:
- error = log_buf_len;
- break;
- default:
- error = -EINVAL;
- break;
- }
-out:
- return error;
-}
-
-SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
-{
- return do_syslog(type, buf, len, SYSLOG_FROM_READER);
-}
-
-/*
- * 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(int level, const char *text, size_t len)
-{
- struct console *con;
-
- trace_console(text, len);
-
- if (level >= console_loglevel && !ignore_loglevel)
- return;
- if (!console_drivers)
- return;
-
- for_each_console(con) {
- if (exclusive_console && con != exclusive_console)
- continue;
- if (!(con->flags & CON_ENABLED))
- continue;
- if (!con->write)
- continue;
- if (!cpu_online(smp_processor_id()) &&
- !(con->flags & CON_ANYTIME))
- continue;
- con->write(con, text, len);
- }
-}
-
-/*
- * Zap console related locks when oopsing. Only zap at most once
- * every 10 seconds, to leave time for slow consoles to print a
- * full oops.
- */
-static void zap_locks(void)
-{
- static unsigned long oops_timestamp;
-
- if (time_after_eq(jiffies, oops_timestamp) &&
- !time_after(jiffies, oops_timestamp + 30 * HZ))
- return;
-
- oops_timestamp = jiffies;
-
- debug_locks_off();
- /* If a crash is occurring, make sure we can't deadlock */
- raw_spin_lock_init(&logbuf_lock);
- /* And make sure that we print immediately */
- sema_init(&console_sem, 1);
-}
-
-/* Check if we have any console registered that can be called early in boot. */
-static int have_callable_console(void)
-{
- struct console *con;
-
- for_each_console(con)
- if (con->flags & CON_ANYTIME)
- return 1;
-
- return 0;
-}
-
-/*
- * Can we actually use the console at this time on this cpu?
- *
- * Console drivers may assume that per-cpu resources have
- * been allocated. So unless they're explicitly marked as
- * being able to cope (CON_ANYTIME) don't call them until
- * this CPU is officially up.
- */
-static inline int can_use_console(unsigned int cpu)
-{
- return cpu_online(cpu) || have_callable_console();
-}
-
-/*
- * Try to get console ownership to actually show the kernel
- * messages from a 'printk'. Return true (and with the
- * console_lock held, and 'console_locked' set) if it
- * is successful, false otherwise.
- *
- * This gets called with the 'logbuf_lock' spinlock held and
- * interrupts disabled. It should return with 'lockbuf_lock'
- * released but interrupts still disabled.
- */
-static int console_trylock_for_printk(unsigned int cpu)
- __releases(&logbuf_lock)
-{
- int retval = 0, wake = 0;
-
- if (console_trylock()) {
- retval = 1;
-
- /*
- * If we can't use the console, we need to release
- * the console semaphore by hand to avoid flushing
- * the buffer. We need to hold the console semaphore
- * in order to do this test safely.
- */
- if (!can_use_console(cpu)) {
- console_locked = 0;
- wake = 1;
- retval = 0;
- }
- }
- logbuf_cpu = UINT_MAX;
- raw_spin_unlock(&logbuf_lock);
- if (wake)
- up(&console_sem);
- return retval;
-}
-
-int printk_delay_msec __read_mostly;
-
-static inline void printk_delay(void)
-{
- if (unlikely(printk_delay_msec)) {
- int m = printk_delay_msec;
-
- while (m--) {
- mdelay(1);
- touch_nmi_watchdog();
- }
- }
-}
-
-/*
- * 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 */
- size_t cons; /* bytes written to console */
- struct task_struct *owner; /* task of first print*/
- u64 ts_nsec; /* time of first print */
- u8 level; /* log level of first message */
- u8 facility; /* log level of first message */
- enum log_flags flags; /* prefix, newline flags */
- bool flushed:1; /* buffer sealed and committed */
-} cont;
-
-static void cont_flush(enum log_flags flags)
-{
- if (cont.flushed)
- return;
- if (cont.len == 0)
- return;
-
- if (cont.cons) {
- /*
- * If a fragment of this line was directly flushed to the
- * console; wait for the console to pick up the rest of the
- * line. LOG_NOCONS suppresses a duplicated output.
- */
- log_store(cont.facility, cont.level, flags | LOG_NOCONS,
- cont.ts_nsec, NULL, 0, cont.buf, cont.len);
- cont.flags = flags;
- cont.flushed = true;
- } else {
- /*
- * If no fragment of this line ever reached the console,
- * just submit it to the store and free the buffer.
- */
- log_store(cont.facility, cont.level, flags, 0,
- NULL, 0, cont.buf, cont.len);
- cont.len = 0;
- }
-}
-
-static bool cont_add(int facility, int level, const char *text, size_t len)
-{
- if (cont.len && cont.flushed)
- return false;
-
- if (cont.len + len > sizeof(cont.buf)) {
- /* the line gets too long, split it up in separate records */
- cont_flush(LOG_CONT);
- return false;
- }
-
- if (!cont.len) {
- cont.facility = facility;
- cont.level = level;
- cont.owner = current;
- cont.ts_nsec = local_clock();
- cont.flags = 0;
- cont.cons = 0;
- cont.flushed = false;
- }
-
- memcpy(cont.buf + cont.len, text, len);
- cont.len += len;
-
- if (cont.len > (sizeof(cont.buf) * 80) / 100)
- cont_flush(LOG_CONT);
-
- return true;
-}
-
-static size_t cont_print_text(char *text, size_t size)
-{
- size_t textlen = 0;
- size_t len;
-
- if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
- textlen += print_time(cont.ts_nsec, text);
- size -= textlen;
- }
-
- len = cont.len - cont.cons;
- if (len > 0) {
- if (len+1 > size)
- len = size-1;
- memcpy(text + textlen, cont.buf + cont.cons, len);
- textlen += len;
- cont.cons = cont.len;
- }
-
- if (cont.flushed) {
- if (cont.flags & LOG_NEWLINE)
- text[textlen++] = '\n';
- /* got everything, release buffer */
- cont.len = 0;
- }
- return textlen;
-}
-
-asmlinkage int vprintk_emit(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, va_list args)
-{
- static int recursion_bug;
- static char textbuf[LOG_LINE_MAX];
- char *text = textbuf;
- size_t text_len;
- enum log_flags lflags = 0;
- unsigned long flags;
- int this_cpu;
- int printed_len = 0;
-
- boot_delay_msec(level);
- printk_delay();
-
- /* This stops the holder of console_sem just where we want him */
- local_irq_save(flags);
- this_cpu = smp_processor_id();
-
- /*
- * Ouch, printk recursed into itself!
- */
- if (unlikely(logbuf_cpu == this_cpu)) {
- /*
- * If a crash is occurring during printk() on this CPU,
- * then try to get the crash message out but make sure
- * we can't deadlock. Otherwise just return to avoid the
- * recursion and return - but flag the recursion so that
- * it can be printed at the next appropriate moment:
- */
- if (!oops_in_progress && !lockdep_recursing(current)) {
- recursion_bug = 1;
- goto out_restore_irqs;
- }
- zap_locks();
- }
-
- lockdep_off();
- raw_spin_lock(&logbuf_lock);
- logbuf_cpu = this_cpu;
-
- if (recursion_bug) {
- static const char recursion_msg[] =
- "BUG: recent printk recursion!";
-
- recursion_bug = 0;
- printed_len += strlen(recursion_msg);
- /* emit KERN_CRIT message */
- log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
- NULL, 0, recursion_msg, printed_len);
- }
-
- /*
- * The printf needs to come first; we need the syslog
- * prefix which might be passed-in as a parameter.
- */
- text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
-
- /* mark and strip 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 = printk_get_level(text);
-
- if (kern_level) {
- const char *end_of_header = printk_skip_level(text);
- switch (kern_level) {
- case '0' ... '7':
- if (level == -1)
- level = kern_level - '0';
- case 'd': /* KERN_DEFAULT */
- lflags |= LOG_PREFIX;
- case 'c': /* KERN_CONT */
- break;
- }
- text_len -= end_of_header - text;
- text = (char *)end_of_header;
- }
- }
-
- if (level == -1)
- level = default_message_loglevel;
-
- if (dict)
- lflags |= LOG_PREFIX|LOG_NEWLINE;
-
- if (!(lflags & LOG_NEWLINE)) {
- /*
- * Flush the conflicting buffer. An earlier newline was missing,
- * or another task also prints continuation lines.
- */
- if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
- cont_flush(LOG_NEWLINE);
-
- /* buffer line if possible, otherwise store it right away */
- if (!cont_add(facility, level, text, text_len))
- log_store(facility, level, lflags | LOG_CONT, 0,
- dict, dictlen, text, text_len);
- } else {
- bool stored = false;
-
- /*
- * If an earlier newline was missing and it was the same task,
- * either merge it with the current buffer and flush, or if
- * there was a race with interrupts (prefix == true) then just
- * flush it out and store this line separately.
- */
- if (cont.len && cont.owner == current) {
- if (!(lflags & LOG_PREFIX))
- stored = cont_add(facility, level, text, text_len);
- cont_flush(LOG_NEWLINE);
- }
-
- if (!stored)
- log_store(facility, level, lflags, 0,
- dict, dictlen, text, text_len);
- }
- printed_len += text_len;
-
- /*
- * Try to acquire and then immediately release the console semaphore.
- * The release will print out buffers and wake up /dev/kmsg and syslog()
- * users.
- *
- * The console_trylock_for_printk() function will release 'logbuf_lock'
- * regardless of whether it actually gets the console semaphore or not.
- */
- if (console_trylock_for_printk(this_cpu))
- console_unlock();
-
- lockdep_on();
-out_restore_irqs:
- local_irq_restore(flags);
-
- return printed_len;
-}
-EXPORT_SYMBOL(vprintk_emit);
-
-asmlinkage int vprintk(const char *fmt, va_list args)
-{
- return vprintk_emit(0, -1, NULL, 0, fmt, args);
-}
-EXPORT_SYMBOL(vprintk);
-
-asmlinkage int printk_emit(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, ...)
-{
- va_list args;
- int r;
-
- va_start(args, fmt);
- r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
- va_end(args);
-
- return r;
-}
-EXPORT_SYMBOL(printk_emit);
-
-/**
- * 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 int printk(const char *fmt, ...)
-{
- va_list args;
- int r;
-
-#ifdef CONFIG_KGDB_KDB
- if (unlikely(kdb_trap_printk)) {
- va_start(args, fmt);
- r = vkdb_printf(fmt, args);
- va_end(args);
- return r;
- }
-#endif
- va_start(args, fmt);
- r = vprintk_emit(0, -1, NULL, 0, fmt, args);
- va_end(args);
-
- return r;
-}
-EXPORT_SYMBOL(printk);
-
-#else /* CONFIG_PRINTK */
-
-#define LOG_LINE_MAX 0
-#define PREFIX_MAX 0
-#define LOG_LINE_MAX 0
-static u64 syslog_seq;
-static u32 syslog_idx;
-static u64 console_seq;
-static u32 console_idx;
-static enum log_flags syslog_prev;
-static u64 log_first_seq;
-static u32 log_first_idx;
-static u64 log_next_seq;
-static enum log_flags console_prev;
-static struct cont {
- size_t len;
- size_t cons;
- u8 level;
- bool flushed:1;
-} cont;
-static struct log *log_from_idx(u32 idx) { return NULL; }
-static u32 log_next(u32 idx) { return 0; }
-static void call_console_drivers(int level, const char *text, size_t len) {}
-static size_t msg_print_text(const struct log *msg, enum log_flags prev,
- bool syslog, char *buf, size_t size) { return 0; }
-static size_t cont_print_text(char *text, size_t size) { return 0; }
-
-#endif /* CONFIG_PRINTK */
-
-#ifdef CONFIG_EARLY_PRINTK
-struct console *early_console;
-
-void early_vprintk(const char *fmt, va_list ap)
-{
- if (early_console) {
- char buf[512];
- int n = vscnprintf(buf, sizeof(buf), fmt, ap);
-
- early_console->write(early_console, buf, n);
- }
-}
-
-asmlinkage void early_printk(const char *fmt, ...)
-{
- va_list ap;
-
- va_start(ap, fmt);
- early_vprintk(fmt, ap);
- va_end(ap);
-}
-#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; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
- if (strcmp(console_cmdline[i].name, name) == 0 &&
- console_cmdline[i].index == idx) {
- if (!brl_options)
- selected_console = i;
- return 0;
- }
- if (i == MAX_CMDLINECONSOLES)
- return -E2BIG;
- if (!brl_options)
- selected_console = i;
- c = &console_cmdline[i];
- strlcpy(c->name, name, sizeof(c->name));
- c->options = options;
-#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
- c->brl_options = brl_options;
-#endif
- c->index = idx;
- return 0;
-}
-/*
- * Set up a list of consoles. Called from init/main.c
- */
-static int __init console_setup(char *str)
-{
- char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
- char *s, *options, *brl_options = NULL;
- int idx;
-
-#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
- if (!memcmp(str, "brl,", 4)) {
- brl_options = "";
- str += 4;
- } else if (!memcmp(str, "brl=", 4)) {
- brl_options = str + 4;
- str = strchr(brl_options, ',');
- if (!str) {
- printk(KERN_ERR "need port name after brl=\n");
- return 1;
- }
- *(str++) = 0;
- }
-#endif
-
- /*
- * 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;
- if ((options = strchr(str, ',')) != NULL)
- *(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 ((*s >= '0' && *s <= '9') || *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);
-}
-
-int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
-{
- struct console_cmdline *c;
- int i;
-
- for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
- if (strcmp(console_cmdline[i].name, name) == 0 &&
- console_cmdline[i].index == idx) {
- c = &console_cmdline[i];
- strlcpy(c->name, name_new, sizeof(c->name));
- c->name[sizeof(c->name) - 1] = 0;
- c->options = options;
- c->index = idx_new;
- return i;
- }
- /* not found */
- return -1;
-}
-
-bool console_suspend_enabled = 1;
-EXPORT_SYMBOL(console_suspend_enabled);
-
-static int __init console_suspend_disable(char *str)
-{
- console_suspend_enabled = 0;
- 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;
- printk("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
- * @self: notifier struct
- * @action: CPU hotplug event
- * @hcpu: unused
- *
- * If printk() is called from a CPU that is not online yet, the messages
- * will be spooled but will not show up on the console. This function is
- * called when a new CPU comes online (or fails to come up), and ensures
- * that any such output gets printed.
- */
-static int console_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
-{
- switch (action) {
- case CPU_ONLINE:
- case CPU_DEAD:
- case CPU_DOWN_FAILED:
- case CPU_UP_CANCELED:
- console_lock();
- console_unlock();
- }
- return NOTIFY_OK;
-}
-
-/**
- * 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;
- mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
-}
-EXPORT_SYMBOL(console_lock);
-
-/**
- * console_trylock - try to lock the console system for exclusive use.
- *
- * Tried 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;
- mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
- return 1;
-}
-EXPORT_SYMBOL(console_trylock);
-
-int is_console_locked(void)
-{
- return console_locked;
-}
-
-static void console_cont_flush(char *text, size_t size)
-{
- unsigned long flags;
- size_t len;
-
- raw_spin_lock_irqsave(&logbuf_lock, flags);
-
- if (!cont.len)
- goto out;
-
- /*
- * We still queue earlier records, likely because the console was
- * busy. The earlier ones need to be printed before this one, we
- * did not flush any fragment so far, so just let it queue up.
- */
- if (console_seq < log_next_seq && !cont.cons)
- goto out;
-
- len = cont_print_text(text, size);
- raw_spin_unlock(&logbuf_lock);
- stop_critical_timings();
- call_console_drivers(cont.level, text, len);
- start_critical_timings();
- local_irq_restore(flags);
- return;
-out:
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-}
-
-/**
- * console_unlock - unlock the console system
- *
- * Releases the console_lock which the caller holds on the console system
- * and the console driver list.
- *
- * While the console_lock was held, console output may have been buffered
- * by printk(). If this is the case, console_unlock(); emits
- * the output prior to releasing the lock.
- *
- * If there is output waiting, we wake /dev/kmsg and syslog() users.
- *
- * console_unlock(); may be called from any context.
- */
-void console_unlock(void)
-{
- static char text[LOG_LINE_MAX + PREFIX_MAX];
- static u64 seen_seq;
- unsigned long flags;
- bool wake_klogd = false;
- bool retry;
-
- if (console_suspended) {
- up(&console_sem);
- return;
- }
-
- console_may_schedule = 0;
-
- /* flush buffered message fragment immediately to console */
- console_cont_flush(text, sizeof(text));
-again:
- for (;;) {
- struct log *msg;
- size_t len;
- int level;
-
- raw_spin_lock_irqsave(&logbuf_lock, flags);
- if (seen_seq != log_next_seq) {
- wake_klogd = true;
- seen_seq = log_next_seq;
- }
-
- if (console_seq < log_first_seq) {
- /* messages are gone, move to first one */
- console_seq = log_first_seq;
- console_idx = log_first_idx;
- console_prev = 0;
- }
-skip:
- if (console_seq == log_next_seq)
- break;
-
- msg = log_from_idx(console_idx);
- if (msg->flags & LOG_NOCONS) {
- /*
- * Skip record we have buffered and already printed
- * directly to the console when we received it.
- */
- console_idx = log_next(console_idx);
- console_seq++;
- /*
- * We will get here again when we register a new
- * CON_PRINTBUFFER console. Clear the flag so we
- * will properly dump everything later.
- */
- msg->flags &= ~LOG_NOCONS;
- console_prev = msg->flags;
- goto skip;
- }
-
- level = msg->level;
- len = msg_print_text(msg, console_prev, false,
- text, sizeof(text));
- console_idx = log_next(console_idx);
- console_seq++;
- console_prev = msg->flags;
- raw_spin_unlock(&logbuf_lock);
-
- stop_critical_timings(); /* don't trace print latency */
- call_console_drivers(level, text, len);
- start_critical_timings();
- local_irq_restore(flags);
- }
- console_locked = 0;
- mutex_release(&console_lock_dep_map, 1, _RET_IP_);
-
- /* Release the exclusive_console once it is used */
- if (unlikely(exclusive_console))
- exclusive_console = NULL;
-
- raw_spin_unlock(&logbuf_lock);
-
- up(&console_sem);
-
- /*
- * Someone could have filled up the buffer again, so re-check if there's
- * something to flush. In case we cannot trylock the console_sem again,
- * there's a new owner and the console_unlock() from them will do the
- * flush, no worries.
- */
- raw_spin_lock(&logbuf_lock);
- retry = console_seq != log_next_seq;
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-
- if (retry && console_trylock())
- goto again;
-
- if (wake_klogd)
- wake_up_klogd();
-}
-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();
-}
-
-/*
- * 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;
- printk(KERN_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;
- unsigned long flags;
- struct console *bcon = NULL;
-
- /*
- * 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)) {
- printk(KERN_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 (preferred_console < 0 || bcon || !console_drivers)
- preferred_console = selected_console;
-
- if (newcon->early_setup)
- newcon->early_setup();
-
- /*
- * 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 (preferred_console < 0) {
- 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;
- preferred_console = 0;
- }
- }
- }
-
- /*
- * See if this console matches one we selected on
- * the command line.
- */
- for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
- i++) {
- if (strcmp(console_cmdline[i].name, newcon->name) != 0)
- continue;
- if (newcon->index >= 0 &&
- newcon->index != console_cmdline[i].index)
- continue;
- if (newcon->index < 0)
- newcon->index = console_cmdline[i].index;
-#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
- if (console_cmdline[i].brl_options) {
- newcon->flags |= CON_BRL;
- braille_register_console(newcon,
- console_cmdline[i].index,
- console_cmdline[i].options,
- console_cmdline[i].brl_options);
- return;
- }
-#endif
- if (newcon->setup &&
- newcon->setup(newcon, console_cmdline[i].options) != 0)
- break;
- newcon->flags |= CON_ENABLED;
- newcon->index = console_cmdline[i].index;
- if (i == selected_console) {
- newcon->flags |= CON_CONSDEV;
- preferred_console = selected_console;
- }
- 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_PRINTBUFFER) {
- /*
- * console_unlock(); will print out the buffered messages
- * for us.
- */
- raw_spin_lock_irqsave(&logbuf_lock, flags);
- console_seq = syslog_seq;
- console_idx = syslog_idx;
- console_prev = syslog_prev;
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
- /*
- * We're about to replay the log buffer. Only do this to the
- * just-registered console to avoid excessive message spam to
- * the already-registered consoles.
- */
- exclusive_console = newcon;
- }
- 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)
- */
- if (bcon &&
- ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
- !keep_bootcon) {
- /* we need to iterate through twice, to make sure we print
- * everything out, before we unregister the console(s)
- */
- printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
- newcon->name, newcon->index);
- for_each_console(bcon)
- if (bcon->flags & CON_BOOT)
- unregister_console(bcon);
- } else {
- printk(KERN_INFO "%sconsole [%s%d] enabled\n",
- (newcon->flags & CON_BOOT) ? "boot" : "" ,
- newcon->name, newcon->index);
- }
-}
-EXPORT_SYMBOL(register_console);
-
-int unregister_console(struct console *console)
-{
- struct console *a, *b;
- int res = 1;
-
-#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
- if (console->flags & CON_BRL)
- return braille_unregister_console(console);
-#endif
-
- 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 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_unlock();
- console_sysfs_notify();
- return res;
-}
-EXPORT_SYMBOL(unregister_console);
-
-static int __init printk_late_init(void)
-{
- struct console *con;
-
- for_each_console(con) {
- if (!keep_bootcon && con->flags & CON_BOOT) {
- printk(KERN_INFO "turn off boot console %s%d\n",
- con->name, con->index);
- unregister_console(con);
- }
- }
- hotcpu_notifier(console_cpu_notify, 0);
- return 0;
-}
-late_initcall(printk_late_init);
-
-#if defined CONFIG_PRINTK
-/*
- * Delayed printk version, for scheduler-internal messages:
- */
-#define PRINTK_BUF_SIZE 512
-
-#define PRINTK_PENDING_WAKEUP 0x01
-#define PRINTK_PENDING_SCHED 0x02
-
-static DEFINE_PER_CPU(int, printk_pending);
-static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
-
-static void wake_up_klogd_work_func(struct irq_work *irq_work)
-{
- int pending = __this_cpu_xchg(printk_pending, 0);
-
- if (pending & PRINTK_PENDING_SCHED) {
- char *buf = __get_cpu_var(printk_sched_buf);
- printk(KERN_WARNING "[sched_delayed] %s", buf);
- }
-
- if (pending & PRINTK_PENDING_WAKEUP)
- wake_up_interruptible(&log_wait);
-}
-
-static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
- .func = wake_up_klogd_work_func,
- .flags = IRQ_WORK_LAZY,
-};
-
-void wake_up_klogd(void)
-{
- preempt_disable();
- if (waitqueue_active(&log_wait)) {
- this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
- irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
- }
- preempt_enable();
-}
-
-int printk_sched(const char *fmt, ...)
-{
- unsigned long flags;
- va_list args;
- char *buf;
- int r;
-
- local_irq_save(flags);
- buf = __get_cpu_var(printk_sched_buf);
-
- va_start(args, fmt);
- r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
- va_end(args);
-
- __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
- irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
- local_irq_restore(flags);
-
- 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)
-{
- if (*caller_jiffies == 0
- || !time_in_range(jiffies, *caller_jiffies,
- *caller_jiffies
- + msecs_to_jiffies(interval_msecs))) {
- *caller_jiffies = jiffies;
- return true;
- }
- return false;
-}
-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;
- unsigned long flags;
-
- 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;
-
- /* initialize iterator with data about the stored records */
- dumper->active = true;
-
- raw_spin_lock_irqsave(&logbuf_lock, flags);
- dumper->cur_seq = clear_seq;
- dumper->cur_idx = clear_idx;
- dumper->next_seq = log_next_seq;
- dumper->next_idx = log_next_idx;
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-
- /* invoke dumper which will iterate over records */
- dumper->dump(dumper, reason);
-
- /* reset iterator */
- dumper->active = false;
- }
- 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 log *msg;
- size_t l = 0;
- bool ret = false;
-
- if (!dumper->active)
- goto out;
-
- if (dumper->cur_seq < log_first_seq) {
- /* messages are gone, move to first available one */
- dumper->cur_seq = log_first_seq;
- dumper->cur_idx = log_first_idx;
- }
-
- /* last entry */
- if (dumper->cur_seq >= log_next_seq)
- goto out;
-
- msg = log_from_idx(dumper->cur_idx);
- l = msg_print_text(msg, 0, syslog, line, size);
-
- dumper->cur_idx = log_next(dumper->cur_idx);
- dumper->cur_seq++;
- ret = true;
-out:
- if (len)
- *len = l;
- return ret;
-}
-
-/**
- * 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)
-{
- unsigned long flags;
- bool ret;
-
- raw_spin_lock_irqsave(&logbuf_lock, flags);
- ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-
- 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)
-{
- unsigned long flags;
- u64 seq;
- u32 idx;
- u64 next_seq;
- u32 next_idx;
- enum log_flags prev;
- size_t l = 0;
- bool ret = false;
-
- if (!dumper->active)
- goto out;
-
- raw_spin_lock_irqsave(&logbuf_lock, flags);
- if (dumper->cur_seq < log_first_seq) {
- /* messages are gone, move to first available one */
- dumper->cur_seq = log_first_seq;
- dumper->cur_idx = log_first_idx;
- }
-
- /* last entry */
- if (dumper->cur_seq >= dumper->next_seq) {
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
- goto out;
- }
-
- /* calculate length of entire buffer */
- seq = dumper->cur_seq;
- idx = dumper->cur_idx;
- prev = 0;
- while (seq < dumper->next_seq) {
- struct log *msg = log_from_idx(idx);
-
- l += msg_print_text(msg, prev, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- prev = msg->flags;
- }
-
- /* move first record forward until length fits into the buffer */
- seq = dumper->cur_seq;
- idx = dumper->cur_idx;
- prev = 0;
- while (l > size && seq < dumper->next_seq) {
- struct log *msg = log_from_idx(idx);
-
- l -= msg_print_text(msg, prev, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- prev = msg->flags;
- }
-
- /* last message in next interation */
- next_seq = seq;
- next_idx = idx;
-
- l = 0;
- prev = 0;
- while (seq < dumper->next_seq) {
- struct log *msg = log_from_idx(idx);
-
- l += msg_print_text(msg, prev, syslog, buf + l, size - l);
- idx = log_next(idx);
- seq++;
- prev = msg->flags;
- }
-
- dumper->next_seq = next_seq;
- dumper->next_idx = next_idx;
- ret = true;
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-out:
- if (len)
- *len = l;
- return ret;
-}
-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->cur_seq = clear_seq;
- dumper->cur_idx = clear_idx;
- dumper->next_seq = log_next_seq;
- dumper->next_idx = log_next_idx;
-}
-
-/**
- * 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)
-{
- unsigned long flags;
-
- raw_spin_lock_irqsave(&logbuf_lock, flags);
- kmsg_dump_rewind_nolock(dumper);
- raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-}
-EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
-
-static char dump_stack_arch_desc_str[128];
-
-/**
- * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
- * @fmt: printf-style format string
- * @...: arguments for the format string
- *
- * The configured string will be printed right after utsname during task
- * dumps. Usually used to add arch-specific system identifiers. If an
- * arch wants to make use of such an ID string, it should initialize this
- * as soon as possible during boot.
- */
-void __init dump_stack_set_arch_desc(const char *fmt, ...)
-{
- va_list args;
-
- va_start(args, fmt);
- vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
- fmt, args);
- va_end(args);
-}
-
-/**
- * dump_stack_print_info - print generic debug info for dump_stack()
- * @log_lvl: log level
- *
- * Arch-specific dump_stack() implementations can use this function to
- * print out the same debug information as the generic dump_stack().
- */
-void dump_stack_print_info(const char *log_lvl)
-{
- printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
- log_lvl, raw_smp_processor_id(), current->pid, current->comm,
- print_tainted(), init_utsname()->release,
- (int)strcspn(init_utsname()->version, " "),
- init_utsname()->version);
-
- if (dump_stack_arch_desc_str[0] != '\0')
- printk("%sHardware name: %s\n",
- log_lvl, dump_stack_arch_desc_str);
-
- print_worker_info(log_lvl, current);
-}
-
-/**
- * show_regs_print_info - print generic debug info for show_regs()
- * @log_lvl: log level
- *
- * show_regs() implementations can use this function to print out generic
- * debug information.
- */
-void show_regs_print_info(const char *log_lvl)
-{
- dump_stack_print_info(log_lvl);
-
- printk("%stask: %p ti: %p task.ti: %p\n",
- log_lvl, current, current_thread_info(),
- task_thread_info(current));
-}
-
-#endif
--- /dev/null
+obj-y = printk.o
--- /dev/null
+/*
+ * 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
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/nmi.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/interrupt.h> /* For in_interrupt() */
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/security.h>
+#include <linux/bootmem.h>
+#include <linux/memblock.h>
+#include <linux/aio.h>
+#include <linux/syscalls.h>
+#include <linux/kexec.h>
+#include <linux/kdb.h>
+#include <linux/ratelimit.h>
+#include <linux/kmsg_dump.h>
+#include <linux/syslog.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/rculist.h>
+#include <linux/poll.h>
+#include <linux/irq_work.h>
+#include <linux/utsname.h>
+
+#include <asm/uaccess.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/printk.h>
+
+/* printk's without a loglevel use this.. */
+#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
+
+/* We show everything that is MORE important than this.. */
+#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
+#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
+
+int console_printk[4] = {
+ DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
+ DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
+ MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
+ DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
+};
+
+/*
+ * 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);
+
+#ifdef CONFIG_LOCKDEP
+static struct lockdep_map console_lock_dep_map = {
+ .name = "console_lock"
+};
+#endif
+
+/*
+ * 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 are racing, but it helps tracking those weird code
+ * path in the console code where we end up in places I want
+ * locked without the console sempahore held
+ */
+static int console_locked, console_suspended;
+
+/*
+ * If exclusive_console is non-NULL then only this console is to be printed to.
+ */
+static struct console *exclusive_console;
+
+/*
+ * Array of consoles built from command line options (console=)
+ */
+struct console_cmdline
+{
+ char name[8]; /* Name of the driver */
+ int index; /* Minor dev. to use */
+ char *options; /* Options for the driver */
+#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
+ char *brl_options; /* Options for braille driver */
+#endif
+};
+
+#define MAX_CMDLINECONSOLES 8
+
+static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
+static int selected_console = -1;
+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;
+
+/*
+ * 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 both 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 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:
+ * "level,sequnum,timestamp;<message text>\n"
+ *
+ * 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.
+ *
+ * Users of the export format should ignore possible additional values
+ * separated by ',', and find the message after the ';' character.
+ */
+
+enum log_flags {
+ LOG_NOCONS = 1, /* already flushed, do not print to console */
+ LOG_NEWLINE = 2, /* text ended with a newline */
+ LOG_PREFIX = 4, /* text started with a prefix */
+ LOG_CONT = 8, /* text is a fragment of a continuation line */
+};
+
+struct log {
+ u64 ts_nsec; /* timestamp in nanoseconds */
+ 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 */
+};
+
+/*
+ * The logbuf_lock protects kmsg buffer, indices, counters. It is also
+ * used in interesting ways to provide interlocking in console_unlock();
+ */
+static DEFINE_RAW_SPINLOCK(logbuf_lock);
+
+#ifdef CONFIG_PRINTK
+DECLARE_WAIT_QUEUE_HEAD(log_wait);
+/* the next printk record to read by syslog(READ) or /proc/kmsg */
+static u64 syslog_seq;
+static u32 syslog_idx;
+static enum log_flags syslog_prev;
+static size_t syslog_partial;
+
+/* index and sequence number of the first record stored in the buffer */
+static u64 log_first_seq;
+static u32 log_first_idx;
+
+/* index and sequence number of the next record to store in the buffer */
+static u64 log_next_seq;
+static u32 log_next_idx;
+
+/* the next printk record to write to the console */
+static u64 console_seq;
+static u32 console_idx;
+static enum log_flags console_prev;
+
+/* the next printk record to read after the last 'clear' command */
+static u64 clear_seq;
+static u32 clear_idx;
+
+#define PREFIX_MAX 32
+#define LOG_LINE_MAX 1024 - PREFIX_MAX
+
+/* record buffer */
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+#define LOG_ALIGN 4
+#else
+#define LOG_ALIGN __alignof__(struct log)
+#endif
+#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
+static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
+static char *log_buf = __log_buf;
+static u32 log_buf_len = __LOG_BUF_LEN;
+
+/* cpu currently holding logbuf_lock */
+static volatile unsigned int logbuf_cpu = UINT_MAX;
+
+/* human readable text of the record */
+static char *log_text(const struct log *msg)
+{
+ return (char *)msg + sizeof(struct log);
+}
+
+/* optional key/value pair dictionary attached to the record */
+static char *log_dict(const struct log *msg)
+{
+ return (char *)msg + sizeof(struct log) + msg->text_len;
+}
+
+/* get record by index; idx must point to valid msg */
+static struct log *log_from_idx(u32 idx)
+{
+ struct log *msg = (struct log *)(log_buf + idx);
+
+ /*
+ * A length == 0 record is the end of buffer marker. Wrap around and
+ * read the message at the start of the buffer.
+ */
+ if (!msg->len)
+ return (struct log *)log_buf;
+ return msg;
+}
+
+/* get next record; idx must point to valid msg */
+static u32 log_next(u32 idx)
+{
+ struct log *msg = (struct log *)(log_buf + idx);
+
+ /* length == 0 indicates the end of the buffer; wrap */
+ /*
+ * A length == 0 record is the end of buffer marker. Wrap around and
+ * read the message at the start of the buffer as *this* one, and
+ * return the one after that.
+ */
+ if (!msg->len) {
+ msg = (struct log *)log_buf;
+ return msg->len;
+ }
+ return idx + msg->len;
+}
+
+/* insert record into the buffer, discard old ones, update heads */
+static void log_store(int facility, int level,
+ enum log_flags flags, u64 ts_nsec,
+ const char *dict, u16 dict_len,
+ const char *text, u16 text_len)
+{
+ struct log *msg;
+ u32 size, pad_len;
+
+ /* number of '\0' padding bytes to next message */
+ size = sizeof(struct log) + text_len + dict_len;
+ pad_len = (-size) & (LOG_ALIGN - 1);
+ size += pad_len;
+
+ while (log_first_seq < log_next_seq) {
+ u32 free;
+
+ if (log_next_idx > log_first_idx)
+ free = max(log_buf_len - log_next_idx, log_first_idx);
+ else
+ free = log_first_idx - log_next_idx;
+
+ if (free > size + sizeof(struct log))
+ break;
+
+ /* drop old messages until we have enough contiuous space */
+ log_first_idx = log_next(log_first_idx);
+ log_first_seq++;
+ }
+
+ if (log_next_idx + size + sizeof(struct log) >= log_buf_len) {
+ /*
+ * This message + an additional empty header does not fit
+ * at the end of the buffer. Add an empty header with len == 0
+ * to signify a wrap around.
+ */
+ memset(log_buf + log_next_idx, 0, sizeof(struct log));
+ log_next_idx = 0;
+ }
+
+ /* fill message */
+ msg = (struct log *)(log_buf + log_next_idx);
+ 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;
+ if (ts_nsec > 0)
+ msg->ts_nsec = ts_nsec;
+ else
+ msg->ts_nsec = local_clock();
+ memset(log_dict(msg) + dict_len, 0, pad_len);
+ msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
+
+ /* insert message */
+ log_next_idx += msg->len;
+ log_next_seq++;
+}
+
+#ifdef CONFIG_SECURITY_DMESG_RESTRICT
+int dmesg_restrict = 1;
+#else
+int dmesg_restrict;
+#endif
+
+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, bool from_file)
+{
+ /*
+ * If this is from /proc/kmsg and we've already opened it, then we've
+ * already done the capabilities checks at open time.
+ */
+ if (from_file && type != SYSLOG_ACTION_OPEN)
+ return 0;
+
+ if (syslog_action_restricted(type)) {
+ if (capable(CAP_SYSLOG))
+ return 0;
+ /*
+ * 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));
+ return 0;
+ }
+ return -EPERM;
+ }
+ return security_syslog(type);
+}
+
+
+/* /dev/kmsg - userspace message inject/listen interface */
+struct devkmsg_user {
+ u64 seq;
+ u32 idx;
+ enum log_flags prev;
+ struct mutex lock;
+ char buf[8192];
+};
+
+static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
+ unsigned long count, loff_t pos)
+{
+ char *buf, *line;
+ int i;
+ int level = default_message_loglevel;
+ int facility = 1; /* LOG_USER */
+ size_t len = iov_length(iv, count);
+ ssize_t ret = len;
+
+ if (len > LOG_LINE_MAX)
+ return -EINVAL;
+ buf = kmalloc(len+1, GFP_KERNEL);
+ if (buf == NULL)
+ return -ENOMEM;
+
+ line = buf;
+ for (i = 0; i < count; i++) {
+ if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ line += iv[i].iov_len;
+ }
+
+ /*
+ * 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;
+
+ i = simple_strtoul(line+1, &endp, 10);
+ if (endp && endp[0] == '>') {
+ level = i & 7;
+ if (i >> 3)
+ facility = i >> 3;
+ endp++;
+ len -= endp - line;
+ line = endp;
+ }
+ }
+ line[len] = '\0';
+
+ printk_emit(facility, level, NULL, 0, "%s", line);
+out:
+ 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 log *msg;
+ u64 ts_usec;
+ size_t i;
+ char cont = '-';
+ size_t len;
+ ssize_t ret;
+
+ if (!user)
+ return -EBADF;
+
+ ret = mutex_lock_interruptible(&user->lock);
+ if (ret)
+ return ret;
+ raw_spin_lock_irq(&logbuf_lock);
+ while (user->seq == log_next_seq) {
+ if (file->f_flags & O_NONBLOCK) {
+ ret = -EAGAIN;
+ raw_spin_unlock_irq(&logbuf_lock);
+ goto out;
+ }
+
+ raw_spin_unlock_irq(&logbuf_lock);
+ ret = wait_event_interruptible(log_wait,
+ user->seq != log_next_seq);
+ if (ret)
+ goto out;
+ raw_spin_lock_irq(&logbuf_lock);
+ }
+
+ if (user->seq < log_first_seq) {
+ /* our last seen message is gone, return error and reset */
+ user->idx = log_first_idx;
+ user->seq = log_first_seq;
+ ret = -EPIPE;
+ raw_spin_unlock_irq(&logbuf_lock);
+ goto out;
+ }
+
+ msg = log_from_idx(user->idx);
+ ts_usec = msg->ts_nsec;
+ do_div(ts_usec, 1000);
+
+ /*
+ * If we couldn't merge continuation line fragments during the print,
+ * export the stored flags to allow an optional external merge of the
+ * records. Merging the records isn't always neccessarily correct, like
+ * when we hit a race during printing. In most cases though, it produces
+ * better readable output. 'c' in the record flags mark the first
+ * fragment of a line, '+' the following.
+ */
+ if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
+ cont = 'c';
+ else if ((msg->flags & LOG_CONT) ||
+ ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
+ cont = '+';
+
+ len = sprintf(user->buf, "%u,%llu,%llu,%c;",
+ (msg->facility << 3) | msg->level,
+ user->seq, ts_usec, cont);
+ user->prev = msg->flags;
+
+ /* escape non-printable characters */
+ for (i = 0; i < msg->text_len; i++) {
+ unsigned char c = log_text(msg)[i];
+
+ if (c < ' ' || c >= 127 || c == '\\')
+ len += sprintf(user->buf + len, "\\x%02x", c);
+ else
+ user->buf[len++] = c;
+ }
+ user->buf[len++] = '\n';
+
+ if (msg->dict_len) {
+ bool line = true;
+
+ for (i = 0; i < msg->dict_len; i++) {
+ unsigned char c = log_dict(msg)[i];
+
+ if (line) {
+ user->buf[len++] = ' ';
+ line = false;
+ }
+
+ if (c == '\0') {
+ user->buf[len++] = '\n';
+ line = true;
+ continue;
+ }
+
+ if (c < ' ' || c >= 127 || c == '\\') {
+ len += sprintf(user->buf + len, "\\x%02x", c);
+ continue;
+ }
+
+ user->buf[len++] = c;
+ }
+ user->buf[len++] = '\n';
+ }
+
+ user->idx = log_next(user->idx);
+ user->seq++;
+ raw_spin_unlock_irq(&logbuf_lock);
+
+ if (len > count) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (copy_to_user(buf, user->buf, len)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ ret = len;
+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 = 0;
+
+ if (!user)
+ return -EBADF;
+ if (offset)
+ return -ESPIPE;
+
+ raw_spin_lock_irq(&logbuf_lock);
+ switch (whence) {
+ case SEEK_SET:
+ /* the first record */
+ user->idx = log_first_idx;
+ user->seq = log_first_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.
+ */
+ user->idx = clear_idx;
+ user->seq = clear_seq;
+ break;
+ case SEEK_END:
+ /* after the last record */
+ user->idx = log_next_idx;
+ user->seq = log_next_seq;
+ break;
+ default:
+ ret = -EINVAL;
+ }
+ raw_spin_unlock_irq(&logbuf_lock);
+ return ret;
+}
+
+static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
+{
+ struct devkmsg_user *user = file->private_data;
+ int ret = 0;
+
+ if (!user)
+ return POLLERR|POLLNVAL;
+
+ poll_wait(file, &log_wait, wait);
+
+ raw_spin_lock_irq(&logbuf_lock);
+ if (user->seq < log_next_seq) {
+ /* return error when data has vanished underneath us */
+ if (user->seq < log_first_seq)
+ ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
+ else
+ ret = POLLIN|POLLRDNORM;
+ }
+ raw_spin_unlock_irq(&logbuf_lock);
+
+ return ret;
+}
+
+static int devkmsg_open(struct inode *inode, struct file *file)
+{
+ struct devkmsg_user *user;
+ int err;
+
+ /* write-only does not need any file context */
+ if ((file->f_flags & O_ACCMODE) == O_WRONLY)
+ return 0;
+
+ 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;
+
+ mutex_init(&user->lock);
+
+ raw_spin_lock_irq(&logbuf_lock);
+ user->idx = log_first_idx;
+ user->seq = log_first_seq;
+ raw_spin_unlock_irq(&logbuf_lock);
+
+ 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;
+
+ mutex_destroy(&user->lock);
+ kfree(user);
+ return 0;
+}
+
+const struct file_operations kmsg_fops = {
+ .open = devkmsg_open,
+ .read = devkmsg_read,
+ .aio_write = devkmsg_writev,
+ .llseek = devkmsg_llseek,
+ .poll = devkmsg_poll,
+ .release = devkmsg_release,
+};
+
+#ifdef CONFIG_KEXEC
+/*
+ * This appends the listed symbols to /proc/vmcoreinfo
+ *
+ * /proc/vmcoreinfo is used by various utiilties, 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_kexec_setup(void)
+{
+ VMCOREINFO_SYMBOL(log_buf);
+ VMCOREINFO_SYMBOL(log_buf_len);
+ VMCOREINFO_SYMBOL(log_first_idx);
+ VMCOREINFO_SYMBOL(log_next_idx);
+ /*
+ * Export struct log size and field offsets. User space tools can
+ * parse it and detect any changes to structure down the line.
+ */
+ VMCOREINFO_STRUCT_SIZE(log);
+ VMCOREINFO_OFFSET(log, ts_nsec);
+ VMCOREINFO_OFFSET(log, len);
+ VMCOREINFO_OFFSET(log, text_len);
+ VMCOREINFO_OFFSET(log, dict_len);
+}
+#endif
+
+/* requested log_buf_len from kernel cmdline */
+static unsigned long __initdata new_log_buf_len;
+
+/* save requested log_buf_len since it's too early to process it */
+static int __init log_buf_len_setup(char *str)
+{
+ unsigned size = memparse(str, &str);
+
+ if (size)
+ size = roundup_pow_of_two(size);
+ if (size > log_buf_len)
+ new_log_buf_len = size;
+
+ return 0;
+}
+early_param("log_buf_len", log_buf_len_setup);
+
+void __init setup_log_buf(int early)
+{
+ unsigned long flags;
+ char *new_log_buf;
+ int free;
+
+ if (!new_log_buf_len)
+ return;
+
+ if (early) {
+ unsigned long mem;
+
+ mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
+ if (!mem)
+ return;
+ new_log_buf = __va(mem);
+ } else {
+ new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
+ }
+
+ if (unlikely(!new_log_buf)) {
+ pr_err("log_buf_len: %ld bytes not available\n",
+ new_log_buf_len);
+ return;
+ }
+
+ raw_spin_lock_irqsave(&logbuf_lock, 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);
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+ pr_info("log_buf_len: %d\n", log_buf_len);
+ pr_info("early log buf free: %d(%d%%)\n",
+ free, (free * 100) / __LOG_BUF_LEN);
+}
+
+static bool __read_mostly ignore_loglevel;
+
+static int __init ignore_loglevel_setup(char *str)
+{
+ ignore_loglevel = 1;
+ printk(KERN_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, to"
+ "print all kernel messages to the console.");
+
+#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 1;
+}
+__setup("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_BOOTING)
+ || (level >= console_loglevel && !ignore_loglevel)) {
+ 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
+
+#if defined(CONFIG_PRINTK_TIME)
+static bool printk_time = 1;
+#else
+static bool printk_time;
+#endif
+module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
+
+static size_t print_time(u64 ts, char *buf)
+{
+ unsigned long rem_nsec;
+
+ if (!printk_time)
+ return 0;
+
+ rem_nsec = do_div(ts, 1000000000);
+
+ if (!buf)
+ return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
+
+ return sprintf(buf, "[%5lu.%06lu] ",
+ (unsigned long)ts, rem_nsec / 1000);
+}
+
+static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
+{
+ size_t len = 0;
+ unsigned int prefix = (msg->facility << 3) | msg->level;
+
+ if (syslog) {
+ if (buf) {
+ len += sprintf(buf, "<%u>", prefix);
+ } else {
+ len += 3;
+ if (prefix > 999)
+ len += 3;
+ else if (prefix > 99)
+ len += 2;
+ else if (prefix > 9)
+ len++;
+ }
+ }
+
+ len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
+ return len;
+}
+
+static size_t msg_print_text(const struct log *msg, enum log_flags prev,
+ bool syslog, char *buf, size_t size)
+{
+ const char *text = log_text(msg);
+ size_t text_size = msg->text_len;
+ bool prefix = true;
+ bool newline = true;
+ size_t len = 0;
+
+ if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
+ prefix = false;
+
+ if (msg->flags & LOG_CONT) {
+ if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
+ prefix = false;
+
+ if (!(msg->flags & LOG_NEWLINE))
+ newline = false;
+ }
+
+ 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 (print_prefix(msg, syslog, NULL) +
+ text_len + 1 >= size - len)
+ break;
+
+ if (prefix)
+ len += print_prefix(msg, syslog, buf + len);
+ memcpy(buf + len, text, text_len);
+ len += text_len;
+ if (next || newline)
+ buf[len++] = '\n';
+ } else {
+ /* SYSLOG_ACTION_* buffer size only calculation */
+ if (prefix)
+ len += print_prefix(msg, syslog, NULL);
+ len += text_len;
+ if (next || newline)
+ len++;
+ }
+
+ prefix = true;
+ text = next;
+ } while (text);
+
+ return len;
+}
+
+static int syslog_print(char __user *buf, int size)
+{
+ char *text;
+ struct log *msg;
+ int len = 0;
+
+ text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ if (!text)
+ return -ENOMEM;
+
+ while (size > 0) {
+ size_t n;
+ size_t skip;
+
+ raw_spin_lock_irq(&logbuf_lock);
+ if (syslog_seq < log_first_seq) {
+ /* messages are gone, move to first one */
+ syslog_seq = log_first_seq;
+ syslog_idx = log_first_idx;
+ syslog_prev = 0;
+ syslog_partial = 0;
+ }
+ if (syslog_seq == log_next_seq) {
+ raw_spin_unlock_irq(&logbuf_lock);
+ break;
+ }
+
+ skip = syslog_partial;
+ msg = log_from_idx(syslog_idx);
+ n = msg_print_text(msg, syslog_prev, true, text,
+ LOG_LINE_MAX + PREFIX_MAX);
+ if (n - syslog_partial <= size) {
+ /* message fits into buffer, move forward */
+ syslog_idx = log_next(syslog_idx);
+ syslog_seq++;
+ syslog_prev = msg->flags;
+ n -= syslog_partial;
+ syslog_partial = 0;
+ } else if (!len){
+ /* partial read(), remember position */
+ n = size;
+ syslog_partial += n;
+ } else
+ n = 0;
+ raw_spin_unlock_irq(&logbuf_lock);
+
+ if (!n)
+ break;
+
+ if (copy_to_user(buf, text + skip, n)) {
+ if (!len)
+ len = -EFAULT;
+ break;
+ }
+
+ len += n;
+ size -= n;
+ buf += n;
+ }
+
+ kfree(text);
+ return len;
+}
+
+static int syslog_print_all(char __user *buf, int size, bool clear)
+{
+ char *text;
+ int len = 0;
+
+ text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ if (!text)
+ return -ENOMEM;
+
+ raw_spin_lock_irq(&logbuf_lock);
+ if (buf) {
+ u64 next_seq;
+ u64 seq;
+ u32 idx;
+ enum log_flags prev;
+
+ if (clear_seq < log_first_seq) {
+ /* messages are gone, move to first available one */
+ clear_seq = log_first_seq;
+ clear_idx = log_first_idx;
+ }
+
+ /*
+ * Find first record that fits, including all following records,
+ * into the user-provided buffer for this dump.
+ */
+ seq = clear_seq;
+ idx = clear_idx;
+ prev = 0;
+ while (seq < log_next_seq) {
+ struct log *msg = log_from_idx(idx);
+
+ len += msg_print_text(msg, prev, true, NULL, 0);
+ prev = msg->flags;
+ idx = log_next(idx);
+ seq++;
+ }
+
+ /* move first record forward until length fits into the buffer */
+ seq = clear_seq;
+ idx = clear_idx;
+ prev = 0;
+ while (len > size && seq < log_next_seq) {
+ struct log *msg = log_from_idx(idx);
+
+ len -= msg_print_text(msg, prev, true, NULL, 0);
+ prev = msg->flags;
+ idx = log_next(idx);
+ seq++;
+ }
+
+ /* last message fitting into this dump */
+ next_seq = log_next_seq;
+
+ len = 0;
+ prev = 0;
+ while (len >= 0 && seq < next_seq) {
+ struct log *msg = log_from_idx(idx);
+ int textlen;
+
+ textlen = msg_print_text(msg, prev, true, text,
+ LOG_LINE_MAX + PREFIX_MAX);
+ if (textlen < 0) {
+ len = textlen;
+ break;
+ }
+ idx = log_next(idx);
+ seq++;
+ prev = msg->flags;
+
+ raw_spin_unlock_irq(&logbuf_lock);
+ if (copy_to_user(buf + len, text, textlen))
+ len = -EFAULT;
+ else
+ len += textlen;
+ raw_spin_lock_irq(&logbuf_lock);
+
+ if (seq < log_first_seq) {
+ /* messages are gone, move to next one */
+ seq = log_first_seq;
+ idx = log_first_idx;
+ prev = 0;
+ }
+ }
+ }
+
+ if (clear) {
+ clear_seq = log_next_seq;
+ clear_idx = log_next_idx;
+ }
+ raw_spin_unlock_irq(&logbuf_lock);
+
+ kfree(text);
+ return len;
+}
+
+int do_syslog(int type, char __user *buf, int len, bool from_file)
+{
+ bool clear = false;
+ static int saved_console_loglevel = -1;
+ int error;
+
+ error = check_syslog_permissions(type, from_file);
+ if (error)
+ goto out;
+
+ error = security_syslog(type);
+ 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 */
+ error = -EINVAL;
+ if (!buf || len < 0)
+ goto out;
+ error = 0;
+ if (!len)
+ goto out;
+ if (!access_ok(VERIFY_WRITE, buf, len)) {
+ error = -EFAULT;
+ goto out;
+ }
+ error = wait_event_interruptible(log_wait,
+ syslog_seq != log_next_seq);
+ if (error)
+ goto out;
+ error = syslog_print(buf, len);
+ break;
+ /* Read/clear last kernel messages */
+ case SYSLOG_ACTION_READ_CLEAR:
+ clear = true;
+ /* FALL THRU */
+ /* Read last kernel messages */
+ case SYSLOG_ACTION_READ_ALL:
+ error = -EINVAL;
+ if (!buf || len < 0)
+ goto out;
+ error = 0;
+ if (!len)
+ goto out;
+ if (!access_ok(VERIFY_WRITE, buf, len)) {
+ error = -EFAULT;
+ goto out;
+ }
+ error = syslog_print_all(buf, len, clear);
+ break;
+ /* Clear ring buffer */
+ case SYSLOG_ACTION_CLEAR:
+ syslog_print_all(NULL, 0, true);
+ break;
+ /* Disable logging to console */
+ case SYSLOG_ACTION_CONSOLE_OFF:
+ if (saved_console_loglevel == -1)
+ saved_console_loglevel = console_loglevel;
+ console_loglevel = minimum_console_loglevel;
+ break;
+ /* Enable logging to console */
+ case SYSLOG_ACTION_CONSOLE_ON:
+ if (saved_console_loglevel != -1) {
+ console_loglevel = saved_console_loglevel;
+ saved_console_loglevel = -1;
+ }
+ break;
+ /* Set level of messages printed to console */
+ case SYSLOG_ACTION_CONSOLE_LEVEL:
+ error = -EINVAL;
+ if (len < 1 || len > 8)
+ goto out;
+ if (len < minimum_console_loglevel)
+ len = minimum_console_loglevel;
+ console_loglevel = len;
+ /* Implicitly re-enable logging to console */
+ saved_console_loglevel = -1;
+ error = 0;
+ break;
+ /* Number of chars in the log buffer */
+ case SYSLOG_ACTION_SIZE_UNREAD:
+ raw_spin_lock_irq(&logbuf_lock);
+ if (syslog_seq < log_first_seq) {
+ /* messages are gone, move to first one */
+ syslog_seq = log_first_seq;
+ syslog_idx = log_first_idx;
+ syslog_prev = 0;
+ syslog_partial = 0;
+ }
+ if (from_file) {
+ /*
+ * Short-cut for poll(/"proc/kmsg") which simply checks
+ * for pending data, not the size; return the count of
+ * records, not the length.
+ */
+ error = log_next_idx - syslog_idx;
+ } else {
+ u64 seq = syslog_seq;
+ u32 idx = syslog_idx;
+ enum log_flags prev = syslog_prev;
+
+ error = 0;
+ while (seq < log_next_seq) {
+ struct log *msg = log_from_idx(idx);
+
+ error += msg_print_text(msg, prev, true, NULL, 0);
+ idx = log_next(idx);
+ seq++;
+ prev = msg->flags;
+ }
+ error -= syslog_partial;
+ }
+ raw_spin_unlock_irq(&logbuf_lock);
+ break;
+ /* Size of the log buffer */
+ case SYSLOG_ACTION_SIZE_BUFFER:
+ error = log_buf_len;
+ break;
+ default:
+ error = -EINVAL;
+ break;
+ }
+out:
+ return error;
+}
+
+SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
+{
+ return do_syslog(type, buf, len, SYSLOG_FROM_READER);
+}
+
+/*
+ * 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(int level, const char *text, size_t len)
+{
+ struct console *con;
+
+ trace_console(text, len);
+
+ if (level >= console_loglevel && !ignore_loglevel)
+ return;
+ if (!console_drivers)
+ return;
+
+ for_each_console(con) {
+ if (exclusive_console && con != exclusive_console)
+ continue;
+ if (!(con->flags & CON_ENABLED))
+ continue;
+ if (!con->write)
+ continue;
+ if (!cpu_online(smp_processor_id()) &&
+ !(con->flags & CON_ANYTIME))
+ continue;
+ con->write(con, text, len);
+ }
+}
+
+/*
+ * Zap console related locks when oopsing. Only zap at most once
+ * every 10 seconds, to leave time for slow consoles to print a
+ * full oops.
+ */
+static void zap_locks(void)
+{
+ static unsigned long oops_timestamp;
+
+ if (time_after_eq(jiffies, oops_timestamp) &&
+ !time_after(jiffies, oops_timestamp + 30 * HZ))
+ return;
+
+ oops_timestamp = jiffies;
+
+ debug_locks_off();
+ /* If a crash is occurring, make sure we can't deadlock */
+ raw_spin_lock_init(&logbuf_lock);
+ /* And make sure that we print immediately */
+ sema_init(&console_sem, 1);
+}
+
+/* Check if we have any console registered that can be called early in boot. */
+static int have_callable_console(void)
+{
+ struct console *con;
+
+ for_each_console(con)
+ if (con->flags & CON_ANYTIME)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Can we actually use the console at this time on this cpu?
+ *
+ * Console drivers may assume that per-cpu resources have
+ * been allocated. So unless they're explicitly marked as
+ * being able to cope (CON_ANYTIME) don't call them until
+ * this CPU is officially up.
+ */
+static inline int can_use_console(unsigned int cpu)
+{
+ return cpu_online(cpu) || have_callable_console();
+}
+
+/*
+ * Try to get console ownership to actually show the kernel
+ * messages from a 'printk'. Return true (and with the
+ * console_lock held, and 'console_locked' set) if it
+ * is successful, false otherwise.
+ *
+ * This gets called with the 'logbuf_lock' spinlock held and
+ * interrupts disabled. It should return with 'lockbuf_lock'
+ * released but interrupts still disabled.
+ */
+static int console_trylock_for_printk(unsigned int cpu)
+ __releases(&logbuf_lock)
+{
+ int retval = 0, wake = 0;
+
+ if (console_trylock()) {
+ retval = 1;
+
+ /*
+ * If we can't use the console, we need to release
+ * the console semaphore by hand to avoid flushing
+ * the buffer. We need to hold the console semaphore
+ * in order to do this test safely.
+ */
+ if (!can_use_console(cpu)) {
+ console_locked = 0;
+ wake = 1;
+ retval = 0;
+ }
+ }
+ logbuf_cpu = UINT_MAX;
+ raw_spin_unlock(&logbuf_lock);
+ if (wake)
+ up(&console_sem);
+ return retval;
+}
+
+int printk_delay_msec __read_mostly;
+
+static inline void printk_delay(void)
+{
+ if (unlikely(printk_delay_msec)) {
+ int m = printk_delay_msec;
+
+ while (m--) {
+ mdelay(1);
+ touch_nmi_watchdog();
+ }
+ }
+}
+
+/*
+ * 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 */
+ size_t cons; /* bytes written to console */
+ struct task_struct *owner; /* task of first print*/
+ u64 ts_nsec; /* time of first print */
+ u8 level; /* log level of first message */
+ u8 facility; /* log level of first message */
+ enum log_flags flags; /* prefix, newline flags */
+ bool flushed:1; /* buffer sealed and committed */
+} cont;
+
+static void cont_flush(enum log_flags flags)
+{
+ if (cont.flushed)
+ return;
+ if (cont.len == 0)
+ return;
+
+ if (cont.cons) {
+ /*
+ * If a fragment of this line was directly flushed to the
+ * console; wait for the console to pick up the rest of the
+ * line. LOG_NOCONS suppresses a duplicated output.
+ */
+ log_store(cont.facility, cont.level, flags | LOG_NOCONS,
+ cont.ts_nsec, NULL, 0, cont.buf, cont.len);
+ cont.flags = flags;
+ cont.flushed = true;
+ } else {
+ /*
+ * If no fragment of this line ever reached the console,
+ * just submit it to the store and free the buffer.
+ */
+ log_store(cont.facility, cont.level, flags, 0,
+ NULL, 0, cont.buf, cont.len);
+ cont.len = 0;
+ }
+}
+
+static bool cont_add(int facility, int level, const char *text, size_t len)
+{
+ if (cont.len && cont.flushed)
+ return false;
+
+ if (cont.len + len > sizeof(cont.buf)) {
+ /* the line gets too long, split it up in separate records */
+ cont_flush(LOG_CONT);
+ return false;
+ }
+
+ if (!cont.len) {
+ cont.facility = facility;
+ cont.level = level;
+ cont.owner = current;
+ cont.ts_nsec = local_clock();
+ cont.flags = 0;
+ cont.cons = 0;
+ cont.flushed = false;
+ }
+
+ memcpy(cont.buf + cont.len, text, len);
+ cont.len += len;
+
+ if (cont.len > (sizeof(cont.buf) * 80) / 100)
+ cont_flush(LOG_CONT);
+
+ return true;
+}
+
+static size_t cont_print_text(char *text, size_t size)
+{
+ size_t textlen = 0;
+ size_t len;
+
+ if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
+ textlen += print_time(cont.ts_nsec, text);
+ size -= textlen;
+ }
+
+ len = cont.len - cont.cons;
+ if (len > 0) {
+ if (len+1 > size)
+ len = size-1;
+ memcpy(text + textlen, cont.buf + cont.cons, len);
+ textlen += len;
+ cont.cons = cont.len;
+ }
+
+ if (cont.flushed) {
+ if (cont.flags & LOG_NEWLINE)
+ text[textlen++] = '\n';
+ /* got everything, release buffer */
+ cont.len = 0;
+ }
+ return textlen;
+}
+
+asmlinkage int vprintk_emit(int facility, int level,
+ const char *dict, size_t dictlen,
+ const char *fmt, va_list args)
+{
+ static int recursion_bug;
+ static char textbuf[LOG_LINE_MAX];
+ char *text = textbuf;
+ size_t text_len;
+ enum log_flags lflags = 0;
+ unsigned long flags;
+ int this_cpu;
+ int printed_len = 0;
+
+ boot_delay_msec(level);
+ printk_delay();
+
+ /* This stops the holder of console_sem just where we want him */
+ local_irq_save(flags);
+ this_cpu = smp_processor_id();
+
+ /*
+ * Ouch, printk recursed into itself!
+ */
+ if (unlikely(logbuf_cpu == this_cpu)) {
+ /*
+ * If a crash is occurring during printk() on this CPU,
+ * then try to get the crash message out but make sure
+ * we can't deadlock. Otherwise just return to avoid the
+ * recursion and return - but flag the recursion so that
+ * it can be printed at the next appropriate moment:
+ */
+ if (!oops_in_progress && !lockdep_recursing(current)) {
+ recursion_bug = 1;
+ goto out_restore_irqs;
+ }
+ zap_locks();
+ }
+
+ lockdep_off();
+ raw_spin_lock(&logbuf_lock);
+ logbuf_cpu = this_cpu;
+
+ if (recursion_bug) {
+ static const char recursion_msg[] =
+ "BUG: recent printk recursion!";
+
+ recursion_bug = 0;
+ printed_len += strlen(recursion_msg);
+ /* emit KERN_CRIT message */
+ log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+ NULL, 0, recursion_msg, printed_len);
+ }
+
+ /*
+ * The printf needs to come first; we need the syslog
+ * prefix which might be passed-in as a parameter.
+ */
+ text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
+
+ /* mark and strip 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 = printk_get_level(text);
+
+ if (kern_level) {
+ const char *end_of_header = printk_skip_level(text);
+ switch (kern_level) {
+ case '0' ... '7':
+ if (level == -1)
+ level = kern_level - '0';
+ case 'd': /* KERN_DEFAULT */
+ lflags |= LOG_PREFIX;
+ case 'c': /* KERN_CONT */
+ break;
+ }
+ text_len -= end_of_header - text;
+ text = (char *)end_of_header;
+ }
+ }
+
+ if (level == -1)
+ level = default_message_loglevel;
+
+ if (dict)
+ lflags |= LOG_PREFIX|LOG_NEWLINE;
+
+ if (!(lflags & LOG_NEWLINE)) {
+ /*
+ * Flush the conflicting buffer. An earlier newline was missing,
+ * or another task also prints continuation lines.
+ */
+ if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
+ cont_flush(LOG_NEWLINE);
+
+ /* buffer line if possible, otherwise store it right away */
+ if (!cont_add(facility, level, text, text_len))
+ log_store(facility, level, lflags | LOG_CONT, 0,
+ dict, dictlen, text, text_len);
+ } else {
+ bool stored = false;
+
+ /*
+ * If an earlier newline was missing and it was the same task,
+ * either merge it with the current buffer and flush, or if
+ * there was a race with interrupts (prefix == true) then just
+ * flush it out and store this line separately.
+ */
+ if (cont.len && cont.owner == current) {
+ if (!(lflags & LOG_PREFIX))
+ stored = cont_add(facility, level, text, text_len);
+ cont_flush(LOG_NEWLINE);
+ }
+
+ if (!stored)
+ log_store(facility, level, lflags, 0,
+ dict, dictlen, text, text_len);
+ }
+ printed_len += text_len;
+
+ /*
+ * Try to acquire and then immediately release the console semaphore.
+ * The release will print out buffers and wake up /dev/kmsg and syslog()
+ * users.
+ *
+ * The console_trylock_for_printk() function will release 'logbuf_lock'
+ * regardless of whether it actually gets the console semaphore or not.
+ */
+ if (console_trylock_for_printk(this_cpu))
+ console_unlock();
+
+ lockdep_on();
+out_restore_irqs:
+ local_irq_restore(flags);
+
+ return printed_len;
+}
+EXPORT_SYMBOL(vprintk_emit);
+
+asmlinkage int vprintk(const char *fmt, va_list args)
+{
+ return vprintk_emit(0, -1, NULL, 0, fmt, args);
+}
+EXPORT_SYMBOL(vprintk);
+
+asmlinkage int printk_emit(int facility, int level,
+ const char *dict, size_t dictlen,
+ const char *fmt, ...)
+{
+ va_list args;
+ int r;
+
+ va_start(args, fmt);
+ r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
+ va_end(args);
+
+ return r;
+}
+EXPORT_SYMBOL(printk_emit);
+
+/**
+ * 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 int printk(const char *fmt, ...)
+{
+ va_list args;
+ int r;
+
+#ifdef CONFIG_KGDB_KDB
+ if (unlikely(kdb_trap_printk)) {
+ va_start(args, fmt);
+ r = vkdb_printf(fmt, args);
+ va_end(args);
+ return r;
+ }
+#endif
+ va_start(args, fmt);
+ r = vprintk_emit(0, -1, NULL, 0, fmt, args);
+ va_end(args);
+
+ return r;
+}
+EXPORT_SYMBOL(printk);
+
+#else /* CONFIG_PRINTK */
+
+#define LOG_LINE_MAX 0
+#define PREFIX_MAX 0
+#define LOG_LINE_MAX 0
+static u64 syslog_seq;
+static u32 syslog_idx;
+static u64 console_seq;
+static u32 console_idx;
+static enum log_flags syslog_prev;
+static u64 log_first_seq;
+static u32 log_first_idx;
+static u64 log_next_seq;
+static enum log_flags console_prev;
+static struct cont {
+ size_t len;
+ size_t cons;
+ u8 level;
+ bool flushed:1;
+} cont;
+static struct log *log_from_idx(u32 idx) { return NULL; }
+static u32 log_next(u32 idx) { return 0; }
+static void call_console_drivers(int level, const char *text, size_t len) {}
+static size_t msg_print_text(const struct log *msg, enum log_flags prev,
+ bool syslog, char *buf, size_t size) { return 0; }
+static size_t cont_print_text(char *text, size_t size) { return 0; }
+
+#endif /* CONFIG_PRINTK */
+
+#ifdef CONFIG_EARLY_PRINTK
+struct console *early_console;
+
+void early_vprintk(const char *fmt, va_list ap)
+{
+ if (early_console) {
+ char buf[512];
+ int n = vscnprintf(buf, sizeof(buf), fmt, ap);
+
+ early_console->write(early_console, buf, n);
+ }
+}
+
+asmlinkage void early_printk(const char *fmt, ...)
+{
+ va_list ap;
+
+ va_start(ap, fmt);
+ early_vprintk(fmt, ap);
+ va_end(ap);
+}
+#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; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
+ if (strcmp(console_cmdline[i].name, name) == 0 &&
+ console_cmdline[i].index == idx) {
+ if (!brl_options)
+ selected_console = i;
+ return 0;
+ }
+ if (i == MAX_CMDLINECONSOLES)
+ return -E2BIG;
+ if (!brl_options)
+ selected_console = i;
+ c = &console_cmdline[i];
+ strlcpy(c->name, name, sizeof(c->name));
+ c->options = options;
+#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
+ c->brl_options = brl_options;
+#endif
+ c->index = idx;
+ return 0;
+}
+/*
+ * Set up a list of consoles. Called from init/main.c
+ */
+static int __init console_setup(char *str)
+{
+ char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
+ char *s, *options, *brl_options = NULL;
+ int idx;
+
+#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
+ if (!memcmp(str, "brl,", 4)) {
+ brl_options = "";
+ str += 4;
+ } else if (!memcmp(str, "brl=", 4)) {
+ brl_options = str + 4;
+ str = strchr(brl_options, ',');
+ if (!str) {
+ printk(KERN_ERR "need port name after brl=\n");
+ return 1;
+ }
+ *(str++) = 0;
+ }
+#endif
+
+ /*
+ * 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;
+ if ((options = strchr(str, ',')) != NULL)
+ *(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 ((*s >= '0' && *s <= '9') || *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);
+}
+
+int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
+{
+ struct console_cmdline *c;
+ int i;
+
+ for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
+ if (strcmp(console_cmdline[i].name, name) == 0 &&
+ console_cmdline[i].index == idx) {
+ c = &console_cmdline[i];
+ strlcpy(c->name, name_new, sizeof(c->name));
+ c->name[sizeof(c->name) - 1] = 0;
+ c->options = options;
+ c->index = idx_new;
+ return i;
+ }
+ /* not found */
+ return -1;
+}
+
+bool console_suspend_enabled = 1;
+EXPORT_SYMBOL(console_suspend_enabled);
+
+static int __init console_suspend_disable(char *str)
+{
+ console_suspend_enabled = 0;
+ 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;
+ printk("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
+ * @self: notifier struct
+ * @action: CPU hotplug event
+ * @hcpu: unused
+ *
+ * If printk() is called from a CPU that is not online yet, the messages
+ * will be spooled but will not show up on the console. This function is
+ * called when a new CPU comes online (or fails to come up), and ensures
+ * that any such output gets printed.
+ */
+static int console_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_DEAD:
+ case CPU_DOWN_FAILED:
+ case CPU_UP_CANCELED:
+ console_lock();
+ console_unlock();
+ }
+ return NOTIFY_OK;
+}
+
+/**
+ * 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;
+ mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
+}
+EXPORT_SYMBOL(console_lock);
+
+/**
+ * console_trylock - try to lock the console system for exclusive use.
+ *
+ * Tried 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;
+ mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
+ return 1;
+}
+EXPORT_SYMBOL(console_trylock);
+
+int is_console_locked(void)
+{
+ return console_locked;
+}
+
+static void console_cont_flush(char *text, size_t size)
+{
+ unsigned long flags;
+ size_t len;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+
+ if (!cont.len)
+ goto out;
+
+ /*
+ * We still queue earlier records, likely because the console was
+ * busy. The earlier ones need to be printed before this one, we
+ * did not flush any fragment so far, so just let it queue up.
+ */
+ if (console_seq < log_next_seq && !cont.cons)
+ goto out;
+
+ len = cont_print_text(text, size);
+ raw_spin_unlock(&logbuf_lock);
+ stop_critical_timings();
+ call_console_drivers(cont.level, text, len);
+ start_critical_timings();
+ local_irq_restore(flags);
+ return;
+out:
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+}
+
+/**
+ * console_unlock - unlock the console system
+ *
+ * Releases the console_lock which the caller holds on the console system
+ * and the console driver list.
+ *
+ * While the console_lock was held, console output may have been buffered
+ * by printk(). If this is the case, console_unlock(); emits
+ * the output prior to releasing the lock.
+ *
+ * If there is output waiting, we wake /dev/kmsg and syslog() users.
+ *
+ * console_unlock(); may be called from any context.
+ */
+void console_unlock(void)
+{
+ static char text[LOG_LINE_MAX + PREFIX_MAX];
+ static u64 seen_seq;
+ unsigned long flags;
+ bool wake_klogd = false;
+ bool retry;
+
+ if (console_suspended) {
+ up(&console_sem);
+ return;
+ }
+
+ console_may_schedule = 0;
+
+ /* flush buffered message fragment immediately to console */
+ console_cont_flush(text, sizeof(text));
+again:
+ for (;;) {
+ struct log *msg;
+ size_t len;
+ int level;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ if (seen_seq != log_next_seq) {
+ wake_klogd = true;
+ seen_seq = log_next_seq;
+ }
+
+ if (console_seq < log_first_seq) {
+ /* messages are gone, move to first one */
+ console_seq = log_first_seq;
+ console_idx = log_first_idx;
+ console_prev = 0;
+ }
+skip:
+ if (console_seq == log_next_seq)
+ break;
+
+ msg = log_from_idx(console_idx);
+ if (msg->flags & LOG_NOCONS) {
+ /*
+ * Skip record we have buffered and already printed
+ * directly to the console when we received it.
+ */
+ console_idx = log_next(console_idx);
+ console_seq++;
+ /*
+ * We will get here again when we register a new
+ * CON_PRINTBUFFER console. Clear the flag so we
+ * will properly dump everything later.
+ */
+ msg->flags &= ~LOG_NOCONS;
+ console_prev = msg->flags;
+ goto skip;
+ }
+
+ level = msg->level;
+ len = msg_print_text(msg, console_prev, false,
+ text, sizeof(text));
+ console_idx = log_next(console_idx);
+ console_seq++;
+ console_prev = msg->flags;
+ raw_spin_unlock(&logbuf_lock);
+
+ stop_critical_timings(); /* don't trace print latency */
+ call_console_drivers(level, text, len);
+ start_critical_timings();
+ local_irq_restore(flags);
+ }
+ console_locked = 0;
+ mutex_release(&console_lock_dep_map, 1, _RET_IP_);
+
+ /* Release the exclusive_console once it is used */
+ if (unlikely(exclusive_console))
+ exclusive_console = NULL;
+
+ raw_spin_unlock(&logbuf_lock);
+
+ up(&console_sem);
+
+ /*
+ * Someone could have filled up the buffer again, so re-check if there's
+ * something to flush. In case we cannot trylock the console_sem again,
+ * there's a new owner and the console_unlock() from them will do the
+ * flush, no worries.
+ */
+ raw_spin_lock(&logbuf_lock);
+ retry = console_seq != log_next_seq;
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+ if (retry && console_trylock())
+ goto again;
+
+ if (wake_klogd)
+ wake_up_klogd();
+}
+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();
+}
+
+/*
+ * 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;
+ printk(KERN_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;
+ unsigned long flags;
+ struct console *bcon = NULL;
+
+ /*
+ * 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)) {
+ printk(KERN_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 (preferred_console < 0 || bcon || !console_drivers)
+ preferred_console = selected_console;
+
+ if (newcon->early_setup)
+ newcon->early_setup();
+
+ /*
+ * 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 (preferred_console < 0) {
+ 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;
+ preferred_console = 0;
+ }
+ }
+ }
+
+ /*
+ * See if this console matches one we selected on
+ * the command line.
+ */
+ for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
+ i++) {
+ if (strcmp(console_cmdline[i].name, newcon->name) != 0)
+ continue;
+ if (newcon->index >= 0 &&
+ newcon->index != console_cmdline[i].index)
+ continue;
+ if (newcon->index < 0)
+ newcon->index = console_cmdline[i].index;
+#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
+ if (console_cmdline[i].brl_options) {
+ newcon->flags |= CON_BRL;
+ braille_register_console(newcon,
+ console_cmdline[i].index,
+ console_cmdline[i].options,
+ console_cmdline[i].brl_options);
+ return;
+ }
+#endif
+ if (newcon->setup &&
+ newcon->setup(newcon, console_cmdline[i].options) != 0)
+ break;
+ newcon->flags |= CON_ENABLED;
+ newcon->index = console_cmdline[i].index;
+ if (i == selected_console) {
+ newcon->flags |= CON_CONSDEV;
+ preferred_console = selected_console;
+ }
+ 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_PRINTBUFFER) {
+ /*
+ * console_unlock(); will print out the buffered messages
+ * for us.
+ */
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ console_seq = syslog_seq;
+ console_idx = syslog_idx;
+ console_prev = syslog_prev;
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+ /*
+ * We're about to replay the log buffer. Only do this to the
+ * just-registered console to avoid excessive message spam to
+ * the already-registered consoles.
+ */
+ exclusive_console = newcon;
+ }
+ 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)
+ */
+ if (bcon &&
+ ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
+ !keep_bootcon) {
+ /* we need to iterate through twice, to make sure we print
+ * everything out, before we unregister the console(s)
+ */
+ printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
+ newcon->name, newcon->index);
+ for_each_console(bcon)
+ if (bcon->flags & CON_BOOT)
+ unregister_console(bcon);
+ } else {
+ printk(KERN_INFO "%sconsole [%s%d] enabled\n",
+ (newcon->flags & CON_BOOT) ? "boot" : "" ,
+ newcon->name, newcon->index);
+ }
+}
+EXPORT_SYMBOL(register_console);
+
+int unregister_console(struct console *console)
+{
+ struct console *a, *b;
+ int res = 1;
+
+#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
+ if (console->flags & CON_BRL)
+ return braille_unregister_console(console);
+#endif
+
+ 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 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_unlock();
+ console_sysfs_notify();
+ return res;
+}
+EXPORT_SYMBOL(unregister_console);
+
+static int __init printk_late_init(void)
+{
+ struct console *con;
+
+ for_each_console(con) {
+ if (!keep_bootcon && con->flags & CON_BOOT) {
+ printk(KERN_INFO "turn off boot console %s%d\n",
+ con->name, con->index);
+ unregister_console(con);
+ }
+ }
+ hotcpu_notifier(console_cpu_notify, 0);
+ return 0;
+}
+late_initcall(printk_late_init);
+
+#if defined CONFIG_PRINTK
+/*
+ * Delayed printk version, for scheduler-internal messages:
+ */
+#define PRINTK_BUF_SIZE 512
+
+#define PRINTK_PENDING_WAKEUP 0x01
+#define PRINTK_PENDING_SCHED 0x02
+
+static DEFINE_PER_CPU(int, printk_pending);
+static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
+
+static void wake_up_klogd_work_func(struct irq_work *irq_work)
+{
+ int pending = __this_cpu_xchg(printk_pending, 0);
+
+ if (pending & PRINTK_PENDING_SCHED) {
+ char *buf = __get_cpu_var(printk_sched_buf);
+ printk(KERN_WARNING "[sched_delayed] %s", buf);
+ }
+
+ if (pending & PRINTK_PENDING_WAKEUP)
+ wake_up_interruptible(&log_wait);
+}
+
+static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
+ .func = wake_up_klogd_work_func,
+ .flags = IRQ_WORK_LAZY,
+};
+
+void wake_up_klogd(void)
+{
+ preempt_disable();
+ if (waitqueue_active(&log_wait)) {
+ this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
+ irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+ }
+ preempt_enable();
+}
+
+int printk_sched(const char *fmt, ...)
+{
+ unsigned long flags;
+ va_list args;
+ char *buf;
+ int r;
+
+ local_irq_save(flags);
+ buf = __get_cpu_var(printk_sched_buf);
+
+ va_start(args, fmt);
+ r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+ va_end(args);
+
+ __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+ irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+ local_irq_restore(flags);
+
+ 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)
+{
+ if (*caller_jiffies == 0
+ || !time_in_range(jiffies, *caller_jiffies,
+ *caller_jiffies
+ + msecs_to_jiffies(interval_msecs))) {
+ *caller_jiffies = jiffies;
+ return true;
+ }
+ return false;
+}
+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;
+ unsigned long flags;
+
+ 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;
+
+ /* initialize iterator with data about the stored records */
+ dumper->active = true;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ dumper->cur_seq = clear_seq;
+ dumper->cur_idx = clear_idx;
+ dumper->next_seq = log_next_seq;
+ dumper->next_idx = log_next_idx;
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+ /* invoke dumper which will iterate over records */
+ dumper->dump(dumper, reason);
+
+ /* reset iterator */
+ dumper->active = false;
+ }
+ 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 log *msg;
+ size_t l = 0;
+ bool ret = false;
+
+ if (!dumper->active)
+ goto out;
+
+ if (dumper->cur_seq < log_first_seq) {
+ /* messages are gone, move to first available one */
+ dumper->cur_seq = log_first_seq;
+ dumper->cur_idx = log_first_idx;
+ }
+
+ /* last entry */
+ if (dumper->cur_seq >= log_next_seq)
+ goto out;
+
+ msg = log_from_idx(dumper->cur_idx);
+ l = msg_print_text(msg, 0, syslog, line, size);
+
+ dumper->cur_idx = log_next(dumper->cur_idx);
+ dumper->cur_seq++;
+ ret = true;
+out:
+ if (len)
+ *len = l;
+ return ret;
+}
+
+/**
+ * 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)
+{
+ unsigned long flags;
+ bool ret;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+ 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)
+{
+ unsigned long flags;
+ u64 seq;
+ u32 idx;
+ u64 next_seq;
+ u32 next_idx;
+ enum log_flags prev;
+ size_t l = 0;
+ bool ret = false;
+
+ if (!dumper->active)
+ goto out;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ if (dumper->cur_seq < log_first_seq) {
+ /* messages are gone, move to first available one */
+ dumper->cur_seq = log_first_seq;
+ dumper->cur_idx = log_first_idx;
+ }
+
+ /* last entry */
+ if (dumper->cur_seq >= dumper->next_seq) {
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+ goto out;
+ }
+
+ /* calculate length of entire buffer */
+ seq = dumper->cur_seq;
+ idx = dumper->cur_idx;
+ prev = 0;
+ while (seq < dumper->next_seq) {
+ struct log *msg = log_from_idx(idx);
+
+ l += msg_print_text(msg, prev, true, NULL, 0);
+ idx = log_next(idx);
+ seq++;
+ prev = msg->flags;
+ }
+
+ /* move first record forward until length fits into the buffer */
+ seq = dumper->cur_seq;
+ idx = dumper->cur_idx;
+ prev = 0;
+ while (l > size && seq < dumper->next_seq) {
+ struct log *msg = log_from_idx(idx);
+
+ l -= msg_print_text(msg, prev, true, NULL, 0);
+ idx = log_next(idx);
+ seq++;
+ prev = msg->flags;
+ }
+
+ /* last message in next interation */
+ next_seq = seq;
+ next_idx = idx;
+
+ l = 0;
+ prev = 0;
+ while (seq < dumper->next_seq) {
+ struct log *msg = log_from_idx(idx);
+
+ l += msg_print_text(msg, prev, syslog, buf + l, size - l);
+ idx = log_next(idx);
+ seq++;
+ prev = msg->flags;
+ }
+
+ dumper->next_seq = next_seq;
+ dumper->next_idx = next_idx;
+ ret = true;
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+out:
+ if (len)
+ *len = l;
+ return ret;
+}
+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->cur_seq = clear_seq;
+ dumper->cur_idx = clear_idx;
+ dumper->next_seq = log_next_seq;
+ dumper->next_idx = log_next_idx;
+}
+
+/**
+ * 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)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&logbuf_lock, flags);
+ kmsg_dump_rewind_nolock(dumper);
+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
+
+static char dump_stack_arch_desc_str[128];
+
+/**
+ * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
+ * @fmt: printf-style format string
+ * @...: arguments for the format string
+ *
+ * The configured string will be printed right after utsname during task
+ * dumps. Usually used to add arch-specific system identifiers. If an
+ * arch wants to make use of such an ID string, it should initialize this
+ * as soon as possible during boot.
+ */
+void __init dump_stack_set_arch_desc(const char *fmt, ...)
+{
+ va_list args;
+
+ va_start(args, fmt);
+ vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
+ fmt, args);
+ va_end(args);
+}
+
+/**
+ * dump_stack_print_info - print generic debug info for dump_stack()
+ * @log_lvl: log level
+ *
+ * Arch-specific dump_stack() implementations can use this function to
+ * print out the same debug information as the generic dump_stack().
+ */
+void dump_stack_print_info(const char *log_lvl)
+{
+ printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
+ log_lvl, raw_smp_processor_id(), current->pid, current->comm,
+ print_tainted(), init_utsname()->release,
+ (int)strcspn(init_utsname()->version, " "),
+ init_utsname()->version);
+
+ if (dump_stack_arch_desc_str[0] != '\0')
+ printk("%sHardware name: %s\n",
+ log_lvl, dump_stack_arch_desc_str);
+
+ print_worker_info(log_lvl, current);
+}
+
+/**
+ * show_regs_print_info - print generic debug info for show_regs()
+ * @log_lvl: log level
+ *
+ * show_regs() implementations can use this function to print out generic
+ * debug information.
+ */
+void show_regs_print_info(const char *log_lvl)
+{
+ dump_stack_print_info(log_lvl);
+
+ printk("%stask: %p ti: %p task.ti: %p\n",
+ log_lvl, current, current_thread_info(),
+ task_thread_info(current));
+}
+
+#endif
projects / kernel.git / commitdiff