mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 09:19:51 +00:00
![Kay Sievers](/assets/img/avatar_default.png)
Arrange the continuation printk() buffering to be fully separated from the ordinary full line users. Limit the exposure to races and wrong printk() line merges to users of continuation only. Ordinary full line users racing against continuation users will no longer affect each other. Multiple continuation users from different threads, racing against each other will not wrongly be merged into a single line, but printed as separate lines. Test output of a kernel module which starts two separate threads which race against each other, one of them printing a single full terminated line: printk("(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)\n"); The other one printing the line, every character separate in a continuation loop: printk("(C"); for (i = 0; i < 58; i++) printk(KERN_CONT "C"); printk(KERN_CONT "C)\n"); Behavior of single and non-thread-aware printk() buffer: # modprobe printk-race printk test init (CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC) (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC) New behavior with separate and thread-aware continuation buffer: # modprobe printk-race printk test init (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC) (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC) (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC) Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Joe Perches <joe@perches.com> Cc: Ted Ts'o <tytso@mit.edu> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2347 lines
57 KiB
C
2347 lines
57 KiB
C
/*
|
|
* 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/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 <asm/uaccess.h>
|
|
|
|
#define CREATE_TRACE_POINTS
|
|
#include <trace/events/printk.h>
|
|
|
|
/*
|
|
* Architectures can override it:
|
|
*/
|
|
void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
|
|
{
|
|
}
|
|
|
|
/* 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 */
|
|
|
|
DECLARE_WAIT_QUEUE_HEAD(log_wait);
|
|
|
|
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);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
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 */
|
|
u16 level; /* syslog level + facility */
|
|
};
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/* the next printk record to read by syslog(READ) or /proc/kmsg */
|
|
static u64 syslog_seq;
|
|
static u32 syslog_idx;
|
|
|
|
/* 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;
|
|
#ifdef CONFIG_PRINTK
|
|
static u32 log_next_idx;
|
|
|
|
/* the next printk record to read after the last 'clear' command */
|
|
static u64 clear_seq;
|
|
static u32 clear_idx;
|
|
|
|
#define LOG_LINE_MAX 1024
|
|
|
|
/* record buffer */
|
|
#if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
|
|
#define LOG_ALIGN 4
|
|
#else
|
|
#define LOG_ALIGN 8
|
|
#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,
|
|
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->level = (facility << 3) | (level & 7);
|
|
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++;
|
|
}
|
|
|
|
/* /dev/kmsg - userspace message inject/listen interface */
|
|
struct devkmsg_user {
|
|
u64 seq;
|
|
u32 idx;
|
|
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))
|
|
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;
|
|
size_t len;
|
|
ssize_t ret;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
|
|
mutex_lock(&user->lock);
|
|
raw_spin_lock(&logbuf_lock);
|
|
while (user->seq == log_next_seq) {
|
|
if (file->f_flags & O_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
raw_spin_unlock(&logbuf_lock);
|
|
goto out;
|
|
}
|
|
|
|
raw_spin_unlock(&logbuf_lock);
|
|
ret = wait_event_interruptible(log_wait,
|
|
user->seq != log_next_seq);
|
|
if (ret)
|
|
goto out;
|
|
raw_spin_lock(&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(&logbuf_lock);
|
|
goto out;
|
|
}
|
|
|
|
msg = log_from_idx(user->idx);
|
|
ts_usec = msg->ts_nsec;
|
|
do_div(ts_usec, 1000);
|
|
len = sprintf(user->buf, "%u,%llu,%llu;",
|
|
msg->level, user->seq, ts_usec);
|
|
|
|
/* escape non-printable characters */
|
|
for (i = 0; i < msg->text_len; i++) {
|
|
unsigned char c = log_text(msg)[i];
|
|
|
|
if (c < ' ' || c >= 128)
|
|
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 >= 128) {
|
|
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(&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(&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(&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(&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;
|
|
ret = POLLIN|POLLRDNORM;
|
|
}
|
|
raw_spin_unlock(&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 = security_syslog(SYSLOG_ACTION_READ_ALL);
|
|
if (err)
|
|
return err;
|
|
|
|
user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
|
|
if (!user)
|
|
return -ENOMEM;
|
|
|
|
mutex_init(&user->lock);
|
|
|
|
raw_spin_lock(&logbuf_lock);
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
raw_spin_unlock(&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);
|
|
}
|
|
#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);
|
|
}
|
|
|
|
#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(void)
|
|
{
|
|
unsigned long long k;
|
|
unsigned long timeout;
|
|
|
|
if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
|
|
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(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#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)) {
|
|
printk_once(KERN_WARNING "%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 0;
|
|
}
|
|
|
|
#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_prefix(const struct log *msg, bool syslog, char *buf)
|
|
{
|
|
size_t len = 0;
|
|
|
|
if (syslog) {
|
|
if (buf) {
|
|
len += sprintf(buf, "<%u>", msg->level);
|
|
} else {
|
|
len += 3;
|
|
if (msg->level > 9)
|
|
len++;
|
|
if (msg->level > 99)
|
|
len++;
|
|
}
|
|
}
|
|
|
|
if (printk_time) {
|
|
if (buf) {
|
|
unsigned long long ts = msg->ts_nsec;
|
|
unsigned long rem_nsec = do_div(ts, 1000000000);
|
|
|
|
len += sprintf(buf + len, "[%5lu.%06lu] ",
|
|
(unsigned long) ts, rem_nsec / 1000);
|
|
} else {
|
|
len += 15;
|
|
}
|
|
}
|
|
|
|
return len;
|
|
}
|
|
|
|
static size_t msg_print_text(const struct log *msg, bool syslog,
|
|
char *buf, size_t size)
|
|
{
|
|
const char *text = log_text(msg);
|
|
size_t text_size = msg->text_len;
|
|
size_t len = 0;
|
|
|
|
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;
|
|
|
|
len += print_prefix(msg, syslog, buf + len);
|
|
memcpy(buf + len, text, text_len);
|
|
len += text_len;
|
|
buf[len++] = '\n';
|
|
} else {
|
|
/* SYSLOG_ACTION_* buffer size only calculation */
|
|
len += print_prefix(msg, syslog, NULL);
|
|
len += text_len + 1;
|
|
}
|
|
|
|
text = next;
|
|
} while (text);
|
|
|
|
return len;
|
|
}
|
|
|
|
static int syslog_print(char __user *buf, int size)
|
|
{
|
|
char *text;
|
|
struct log *msg;
|
|
int len;
|
|
|
|
text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
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;
|
|
}
|
|
msg = log_from_idx(syslog_idx);
|
|
len = msg_print_text(msg, true, text, LOG_LINE_MAX);
|
|
syslog_idx = log_next(syslog_idx);
|
|
syslog_seq++;
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
|
|
if (len > 0 && copy_to_user(buf, text, len))
|
|
len = -EFAULT;
|
|
|
|
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, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
if (buf) {
|
|
u64 next_seq;
|
|
u64 seq;
|
|
u32 idx;
|
|
|
|
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;
|
|
while (seq < log_next_seq) {
|
|
struct log *msg = log_from_idx(idx);
|
|
|
|
len += msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
seq = clear_seq;
|
|
idx = clear_idx;
|
|
while (len > size && seq < log_next_seq) {
|
|
struct log *msg = log_from_idx(idx);
|
|
|
|
len -= msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* last message in this dump */
|
|
next_seq = log_next_seq;
|
|
|
|
len = 0;
|
|
while (len >= 0 && seq < next_seq) {
|
|
struct log *msg = log_from_idx(idx);
|
|
int textlen;
|
|
|
|
textlen = msg_print_text(msg, true, text, LOG_LINE_MAX);
|
|
if (textlen < 0) {
|
|
len = textlen;
|
|
break;
|
|
}
|
|
idx = log_next(idx);
|
|
seq++;
|
|
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
|
|
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);
|
|
/* 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;
|
|
}
|
|
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;
|
|
u32 idx;
|
|
|
|
error = 0;
|
|
seq = syslog_seq;
|
|
idx = syslog_idx;
|
|
while (seq < log_next_seq) {
|
|
struct log *msg = log_from_idx(idx);
|
|
|
|
error += msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
}
|
|
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_CALL);
|
|
}
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
/* kdb dmesg command needs access to the syslog buffer. do_syslog()
|
|
* uses locks so it cannot be used during debugging. Just tell kdb
|
|
* where the start and end of the physical and logical logs are. This
|
|
* is equivalent to do_syslog(3).
|
|
*/
|
|
void kdb_syslog_data(char *syslog_data[4])
|
|
{
|
|
syslog_data[0] = log_buf;
|
|
syslog_data[1] = log_buf + log_buf_len;
|
|
syslog_data[2] = log_buf + log_first_idx;
|
|
syslog_data[3] = log_buf + log_next_idx;
|
|
}
|
|
#endif /* CONFIG_KGDB_KDB */
|
|
|
|
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.");
|
|
|
|
/*
|
|
* 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, 0, len, 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;
|
|
if (wake)
|
|
up(&console_sem);
|
|
raw_spin_unlock(&logbuf_lock);
|
|
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();
|
|
}
|
|
}
|
|
}
|
|
|
|
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 cont_buf[LOG_LINE_MAX];
|
|
static size_t cont_len;
|
|
static int cont_level;
|
|
static struct task_struct *cont_task;
|
|
static char textbuf[LOG_LINE_MAX];
|
|
char *text = textbuf;
|
|
size_t text_len;
|
|
unsigned long flags;
|
|
int this_cpu;
|
|
bool newline = false;
|
|
bool prefix = false;
|
|
int printed_len = 0;
|
|
|
|
boot_delay_msec();
|
|
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, 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--;
|
|
newline = true;
|
|
}
|
|
|
|
/* strip syslog prefix and extract log level or control flags */
|
|
if (text[0] == '<' && text[1] && text[2] == '>') {
|
|
switch (text[1]) {
|
|
case '0' ... '7':
|
|
if (level == -1)
|
|
level = text[1] - '0';
|
|
case 'd': /* KERN_DEFAULT */
|
|
prefix = true;
|
|
case 'c': /* KERN_CONT */
|
|
text += 3;
|
|
text_len -= 3;
|
|
}
|
|
}
|
|
|
|
if (level == -1)
|
|
level = default_message_loglevel;
|
|
|
|
if (dict) {
|
|
prefix = true;
|
|
newline = true;
|
|
}
|
|
|
|
if (!newline) {
|
|
if (cont_len && (prefix || cont_task != current)) {
|
|
/*
|
|
* Flush earlier buffer, which is either from a
|
|
* different thread, or when we got a new prefix.
|
|
*/
|
|
log_store(facility, cont_level, NULL, 0, cont_buf, cont_len);
|
|
cont_len = 0;
|
|
}
|
|
|
|
if (!cont_len) {
|
|
cont_level = level;
|
|
cont_task = current;
|
|
}
|
|
|
|
/* buffer or append to earlier buffer from the same thread */
|
|
if (cont_len + text_len > sizeof(cont_buf))
|
|
text_len = sizeof(cont_buf) - cont_len;
|
|
memcpy(cont_buf + cont_len, text, text_len);
|
|
cont_len += text_len;
|
|
} else {
|
|
if (cont_len && cont_task == current) {
|
|
if (prefix) {
|
|
/*
|
|
* New prefix from the same thread; flush. We
|
|
* either got no earlier newline, or we race
|
|
* with an interrupt.
|
|
*/
|
|
log_store(facility, cont_level,
|
|
NULL, 0, cont_buf, cont_len);
|
|
cont_len = 0;
|
|
}
|
|
|
|
/* append to the earlier buffer and flush */
|
|
if (cont_len + text_len > sizeof(cont_buf))
|
|
text_len = sizeof(cont_buf) - cont_len;
|
|
memcpy(cont_buf + cont_len, text, text_len);
|
|
cont_len += text_len;
|
|
log_store(facility, cont_level,
|
|
NULL, 0, cont_buf, cont_len);
|
|
cont_len = 0;
|
|
cont_task = NULL;
|
|
printed_len = cont_len;
|
|
} else {
|
|
/* ordinary single and terminated line */
|
|
log_store(facility, level,
|
|
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
|
|
|
|
#define LOG_LINE_MAX 0
|
|
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, bool syslog,
|
|
char *buf, size_t size) { return 0; }
|
|
|
|
#endif /* CONFIG_PRINTK */
|
|
|
|
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 __cpuinit console_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
switch (action) {
|
|
case CPU_ONLINE:
|
|
case CPU_DEAD:
|
|
case CPU_DYING:
|
|
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)
|
|
{
|
|
BUG_ON(in_interrupt());
|
|
down(&console_sem);
|
|
if (console_suspended)
|
|
return;
|
|
console_locked = 1;
|
|
console_may_schedule = 1;
|
|
}
|
|
EXPORT_SYMBOL(console_lock);
|
|
|
|
/**
|
|
* console_trylock - try to lock the console system for exclusive use.
|
|
*
|
|
* 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;
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(console_trylock);
|
|
|
|
int is_console_locked(void)
|
|
{
|
|
return console_locked;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
|
|
void printk_tick(void)
|
|
{
|
|
if (__this_cpu_read(printk_pending)) {
|
|
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);
|
|
}
|
|
}
|
|
|
|
int printk_needs_cpu(int cpu)
|
|
{
|
|
if (cpu_is_offline(cpu))
|
|
printk_tick();
|
|
return __this_cpu_read(printk_pending);
|
|
}
|
|
|
|
void wake_up_klogd(void)
|
|
{
|
|
if (waitqueue_active(&log_wait))
|
|
this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
|
|
}
|
|
|
|
/* the next printk record to write to the console */
|
|
static u64 console_seq;
|
|
static u32 console_idx;
|
|
|
|
/**
|
|
* 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 u64 seen_seq;
|
|
unsigned long flags;
|
|
bool wake_klogd = false;
|
|
bool retry;
|
|
|
|
if (console_suspended) {
|
|
up(&console_sem);
|
|
return;
|
|
}
|
|
|
|
console_may_schedule = 0;
|
|
|
|
again:
|
|
for (;;) {
|
|
struct log *msg;
|
|
static char text[LOG_LINE_MAX];
|
|
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;
|
|
}
|
|
|
|
if (console_seq == log_next_seq)
|
|
break;
|
|
|
|
msg = log_from_idx(console_idx);
|
|
level = msg->level & 7;
|
|
|
|
len = msg_print_text(msg, false, text, sizeof(text));
|
|
|
|
console_idx = log_next(console_idx);
|
|
console_seq++;
|
|
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;
|
|
|
|
/* 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;
|
|
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
|
|
|
|
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);
|
|
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
|
|
*
|
|
* Iterate through each of the dump devices and call the oops/panic
|
|
* callbacks with the log buffer.
|
|
*/
|
|
void kmsg_dump(enum kmsg_dump_reason reason)
|
|
{
|
|
u64 idx;
|
|
struct kmsg_dumper *dumper;
|
|
const char *s1, *s2;
|
|
unsigned long l1, l2;
|
|
unsigned long flags;
|
|
|
|
if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
|
|
return;
|
|
|
|
/* Theoretically, the log could move on after we do this, but
|
|
there's not a lot we can do about that. The new messages
|
|
will overwrite the start of what we dump. */
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
if (syslog_seq < log_first_seq)
|
|
idx = syslog_idx;
|
|
else
|
|
idx = log_first_idx;
|
|
|
|
if (idx > log_next_idx) {
|
|
s1 = log_buf;
|
|
l1 = log_next_idx;
|
|
|
|
s2 = log_buf + idx;
|
|
l2 = log_buf_len - idx;
|
|
} else {
|
|
s1 = "";
|
|
l1 = 0;
|
|
|
|
s2 = log_buf + idx;
|
|
l2 = log_next_idx - idx;
|
|
}
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(dumper, &dump_list, list)
|
|
dumper->dump(dumper, reason, s1, l1, s2, l2);
|
|
rcu_read_unlock();
|
|
}
|
|
#endif
|