diff options
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/Makefile | 2 | ||||
| -rw-r--r-- | kernel/printk/braille.c | 49 | ||||
| -rw-r--r-- | kernel/printk/braille.h | 48 | ||||
| -rw-r--r-- | kernel/printk/console_cmdline.h | 14 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 3080 |
5 files changed, 3193 insertions, 0 deletions
diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile new file mode 100644 index 000000000..85405bdcf --- /dev/null +++ b/kernel/printk/Makefile @@ -0,0 +1,2 @@ +obj-y = printk.o +obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c new file mode 100644 index 000000000..276762f3a --- /dev/null +++ b/kernel/printk/braille.c @@ -0,0 +1,49 @@ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/console.h> +#include <linux/string.h> + +#include "console_cmdline.h" +#include "braille.h" + +char *_braille_console_setup(char **str, char **brl_options) +{ + 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) + pr_err("need port name after brl=\n"); + else + *((*str)++) = 0; + } else + return NULL; + + return *str; +} + +int +_braille_register_console(struct console *console, struct console_cmdline *c) +{ + int rtn = 0; + + if (c->brl_options) { + console->flags |= CON_BRL; + rtn = braille_register_console(console, c->index, c->options, + c->brl_options); + } + + return rtn; +} + +int +_braille_unregister_console(struct console *console) +{ + if (console->flags & CON_BRL) + return braille_unregister_console(console); + + return 0; +} diff --git a/kernel/printk/braille.h b/kernel/printk/braille.h new file mode 100644 index 000000000..769d77114 --- /dev/null +++ b/kernel/printk/braille.h @@ -0,0 +1,48 @@ +#ifndef _PRINTK_BRAILLE_H +#define _PRINTK_BRAILLE_H + +#ifdef CONFIG_A11Y_BRAILLE_CONSOLE + +static inline void +braille_set_options(struct console_cmdline *c, char *brl_options) +{ + c->brl_options = brl_options; +} + +char * +_braille_console_setup(char **str, char **brl_options); + +int +_braille_register_console(struct console *console, struct console_cmdline *c); + +int +_braille_unregister_console(struct console *console); + +#else + +static inline void +braille_set_options(struct console_cmdline *c, char *brl_options) +{ +} + +static inline char * +_braille_console_setup(char **str, char **brl_options) +{ + return NULL; +} + +static inline int +_braille_register_console(struct console *console, struct console_cmdline *c) +{ + return 0; +} + +static inline int +_braille_unregister_console(struct console *console) +{ + return 0; +} + +#endif + +#endif diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdline.h new file mode 100644 index 000000000..2ca4a8b5f --- /dev/null +++ b/kernel/printk/console_cmdline.h @@ -0,0 +1,14 @@ +#ifndef _CONSOLE_CMDLINE_H +#define _CONSOLE_CMDLINE_H + +struct console_cmdline +{ + char name[16]; /* 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 +}; + +#endif diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c new file mode 100644 index 000000000..83cf08088 --- /dev/null +++ b/kernel/printk/printk.c @@ -0,0 +1,3080 @@ +/* + * 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/suspend.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 <linux/ctype.h> +#include <linux/uio.h> + +#include <asm/uaccess.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/printk.h> + +#include "console_cmdline.h" +#include "braille.h" + +int console_printk[4] = { + CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ + MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ + CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ + CONSOLE_LOGLEVEL_DEFAULT, /* 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 + +/* + * Helper macros to handle lockdep when locking/unlocking console_sem. We use + * macros instead of functions so that _RET_IP_ contains useful information. + */ +#define down_console_sem() do { \ + down(&console_sem);\ + mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ +} while (0) + +static int __down_trylock_console_sem(unsigned long ip) +{ + if (down_trylock(&console_sem)) + return 1; + mutex_acquire(&console_lock_dep_map, 0, 1, ip); + return 0; +} +#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) + +#define up_console_sem() do { \ + mutex_release(&console_lock_dep_map, 1, _RET_IP_);\ + up(&console_sem);\ +} while (0) + +/* + * This is used for debugging the mess that is the VT code by + * keeping track if we have the console semaphore held. It's + * definitely not the perfect debug tool (we don't know if _WE_ + * hold it and are racing, but it helps tracking those weird code + * paths in the console code where we end up in places I want + * locked without the console sempahore held). + */ +static int console_locked, console_suspended; + +/* + * 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=) + */ + +#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 entries are maintained when messages are + * stored. + * + * If the heads indicate available messages, the length in the header + * tells the start next message. A length == 0 for the next message + * indicates a wrap-around to the beginning of the buffer. + * + * Every record carries the monotonic timestamp in microseconds, as well as + * the standard userspace syslog level and syslog facility. The usual + * kernel messages use LOG_KERN; userspace-injected messages always carry + * a matching syslog facility, by default LOG_USER. The origin of every + * message can be reliably determined that way. + * + * The human readable log message directly follows the message header. The + * length of the message text is stored in the header, the stored message + * is not terminated. + * + * Optionally, a message can carry a dictionary of properties (key/value pairs), + * to provide userspace with a machine-readable message context. + * + * Examples for well-defined, commonly used property names are: + * DEVICE=b12:8 device identifier + * b12:8 block dev_t + * c127:3 char dev_t + * n8 netdev ifindex + * +sound:card0 subsystem:devname + * SUBSYSTEM=pci driver-core subsystem name + * + * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value + * follows directly after a '=' character. Every property is terminated by + * a '\0' character. The last property is not terminated. + * + * Example of a message structure: + * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec + * 0008 34 00 record is 52 bytes long + * 000a 0b 00 text is 11 bytes long + * 000c 1f 00 dictionary is 23 bytes long + * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) + * 0010 69 74 27 73 20 61 20 6c "it's a l" + * 69 6e 65 "ine" + * 001b 44 45 56 49 43 "DEVIC" + * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" + * 52 49 56 45 52 3d 62 75 "RIVER=bu" + * 67 "g" + * 0032 00 00 00 padding to next message header + * + * The 'struct printk_log' buffer header must never be directly exported to + * userspace, it is a kernel-private implementation detail that might + * need to be changed in the future, when the requirements change. + * + * /dev/kmsg exports the structured data in the following line format: + * "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 printk_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. This can be taken + * within the scheduler's rq lock. It must be released before calling + * console_unlock() or anything else that might wake up a process. + */ +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 printk_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; + +#ifdef CONFIG_TOI_INCREMENTAL +void toi_set_logbuf_untracked(void) +{ + int i; + struct page *log_buf_start_page = virt_to_page(__log_buf); + + printk("Not protecting kernel printk log buffer (%p-%p).\n", + __log_buf, __log_buf + __LOG_BUF_LEN); + + for (i = 0; i < (1 << (CONFIG_LOG_BUF_SHIFT - PAGE_SHIFT)); i++) + SetPageTOI_Untracked(log_buf_start_page + i); +} +#endif + +/* Return log buffer address */ +char *log_buf_addr_get(void) +{ + return log_buf; +} + +/* Return log buffer size */ +u32 log_buf_len_get(void) +{ + return log_buf_len; +} + +/* human readable text of the record */ +static char *log_text(const struct printk_log *msg) +{ + return (char *)msg + sizeof(struct printk_log); +} + +/* optional key/value pair dictionary attached to the record */ +static char *log_dict(const struct printk_log *msg) +{ + return (char *)msg + sizeof(struct printk_log) + msg->text_len; +} + +/* get record by index; idx must point to valid msg */ +static struct printk_log *log_from_idx(u32 idx) +{ + struct printk_log *msg = (struct printk_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 printk_log *)log_buf; + return msg; +} + +/* get next record; idx must point to valid msg */ +static u32 log_next(u32 idx) +{ + struct printk_log *msg = (struct printk_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 printk_log *)log_buf; + return msg->len; + } + return idx + msg->len; +} + +/* + * Check whether there is enough free space for the given message. + * + * The same values of first_idx and next_idx mean that the buffer + * is either empty or full. + * + * If the buffer is empty, we must respect the position of the indexes. + * They cannot be reset to the beginning of the buffer. + */ +static int logbuf_has_space(u32 msg_size, bool empty) +{ + u32 free; + + if (log_next_idx > log_first_idx || empty) + free = max(log_buf_len - log_next_idx, log_first_idx); + else + free = log_first_idx - log_next_idx; + + /* + * We need space also for an empty header that signalizes wrapping + * of the buffer. + */ + return free >= msg_size + sizeof(struct printk_log); +} + +static int log_make_free_space(u32 msg_size) +{ + while (log_first_seq < log_next_seq) { + if (logbuf_has_space(msg_size, false)) + return 0; + /* drop old messages until we have enough contiguous space */ + log_first_idx = log_next(log_first_idx); + log_first_seq++; + } + + /* sequence numbers are equal, so the log buffer is empty */ + if (logbuf_has_space(msg_size, true)) + return 0; + + return -ENOMEM; +} + +/* compute the message size including the padding bytes */ +static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) +{ + u32 size; + + size = sizeof(struct printk_log) + text_len + dict_len; + *pad_len = (-size) & (LOG_ALIGN - 1); + size += *pad_len; + + return size; +} + +/* + * Define how much of the log buffer we could take at maximum. The value + * must be greater than two. Note that only half of the buffer is available + * when the index points to the middle. + */ +#define MAX_LOG_TAKE_PART 4 +static const char trunc_msg[] = "<truncated>"; + +static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, + u16 *dict_len, u32 *pad_len) +{ + /* + * The message should not take the whole buffer. Otherwise, it might + * get removed too soon. + */ + u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; + if (*text_len > max_text_len) + *text_len = max_text_len; + /* enable the warning message */ + *trunc_msg_len = strlen(trunc_msg); + /* disable the "dict" completely */ + *dict_len = 0; + /* compute the size again, count also the warning message */ + return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); +} + +/* insert record into the buffer, discard old ones, update heads */ +static int 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 printk_log *msg; + u32 size, pad_len; + u16 trunc_msg_len = 0; + + /* number of '\0' padding bytes to next message */ + size = msg_used_size(text_len, dict_len, &pad_len); + + if (log_make_free_space(size)) { + /* truncate the message if it is too long for empty buffer */ + size = truncate_msg(&text_len, &trunc_msg_len, + &dict_len, &pad_len); + /* survive when the log buffer is too small for trunc_msg */ + if (log_make_free_space(size)) + return 0; + } + + if (log_next_idx + size + sizeof(struct printk_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 printk_log)); + log_next_idx = 0; + } + + /* fill message */ + msg = (struct printk_log *)(log_buf + log_next_idx); + memcpy(log_text(msg), text, text_len); + msg->text_len = text_len; + if (trunc_msg_len) { + memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); + msg->text_len += trunc_msg_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 = size; + + /* insert message */ + log_next_idx += msg->len; + log_next_seq++; + + return msg->text_len; +} + +int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); + +static int syslog_action_restricted(int type) +{ + if (dmesg_restrict) + return 1; + /* + * Unless restricted, we allow "read all" and "get buffer size" + * for everybody. + */ + return type != SYSLOG_ACTION_READ_ALL && + type != SYSLOG_ACTION_SIZE_BUFFER; +} + +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) + goto ok; + + if (syslog_action_restricted(type)) { + if (capable(CAP_SYSLOG)) + goto ok; + /* + * For historical reasons, accept CAP_SYS_ADMIN too, with + * a warning. + */ + if (capable(CAP_SYS_ADMIN)) { + pr_warn_once("%s (%d): Attempt to access syslog with " + "CAP_SYS_ADMIN but no CAP_SYSLOG " + "(deprecated).\n", + current->comm, task_pid_nr(current)); + goto ok; + } + return -EPERM; + } +ok: + return security_syslog(type); +} + + +/* /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_write(struct kiocb *iocb, struct iov_iter *from) +{ + char *buf, *line; + int i; + int level = default_message_loglevel; + int facility = 1; /* LOG_USER */ + size_t len = iov_iter_count(from); + ssize_t ret = len; + + if (len > LOG_LINE_MAX) + return -EINVAL; + buf = kmalloc(len+1, GFP_KERNEL); + if (buf == NULL) + return -ENOMEM; + + buf[len] = '\0'; + if (copy_from_iter(buf, len, from) != len) { + kfree(buf); + return -EFAULT; + } + + /* + * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace + * the decimal value represents 32bit, the lower 3 bit are the log + * level, the rest are the log facility. + * + * If no prefix or no userspace facility is specified, we + * enforce LOG_USER, to be able to reliably distinguish + * kernel-generated messages from userspace-injected ones. + */ + line = buf; + if (line[0] == '<') { + char *endp = NULL; + + 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; + } + } + + printk_emit(facility, level, NULL, 0, "%s", line); + kfree(buf); + return ret; +} + +static ssize_t devkmsg_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + struct devkmsg_user *user = file->private_data; + struct printk_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, + .write_iter = devkmsg_write, + .llseek = devkmsg_llseek, + .poll = devkmsg_poll, + .release = devkmsg_release, +}; + +#ifdef CONFIG_KEXEC +/* + * This appends the listed symbols to /proc/vmcore + * + * /proc/vmcore is used by various utilities, like crash and makedumpfile to + * obtain access to symbols that are otherwise very difficult to locate. These + * symbols are specifically used so that utilities can access and extract the + * dmesg log from a vmcore file after a crash. + */ +void log_buf_kexec_setup(void) +{ + VMCOREINFO_SYMBOL(log_buf); + VMCOREINFO_SYMBOL(log_buf_len); + VMCOREINFO_SYMBOL(log_first_idx); + VMCOREINFO_SYMBOL(log_next_idx); + /* + * Export struct printk_log size and field offsets. User space tools can + * parse it and detect any changes to structure down the line. + */ + VMCOREINFO_STRUCT_SIZE(printk_log); + VMCOREINFO_OFFSET(printk_log, ts_nsec); + VMCOREINFO_OFFSET(printk_log, len); + VMCOREINFO_OFFSET(printk_log, text_len); + VMCOREINFO_OFFSET(printk_log, dict_len); +} +#endif + +/* requested log_buf_len from kernel cmdline */ +static unsigned long __initdata new_log_buf_len; + +/* we practice scaling the ring buffer by powers of 2 */ +static void __init log_buf_len_update(unsigned size) +{ + if (size) + size = roundup_pow_of_two(size); + if (size > log_buf_len) + new_log_buf_len = size; +} + +/* 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); + + log_buf_len_update(size); + + return 0; +} +early_param("log_buf_len", log_buf_len_setup); + +#ifdef CONFIG_SMP +#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) + +static void __init log_buf_add_cpu(void) +{ + unsigned int cpu_extra; + + /* + * archs should set up cpu_possible_bits properly with + * set_cpu_possible() after setup_arch() but just in + * case lets ensure this is valid. + */ + if (num_possible_cpus() == 1) + return; + + cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; + + /* by default this will only continue through for large > 64 CPUs */ + if (cpu_extra <= __LOG_BUF_LEN / 2) + return; + + pr_info("log_buf_len individual max cpu contribution: %d bytes\n", + __LOG_CPU_MAX_BUF_LEN); + pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", + cpu_extra); + pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); + + log_buf_len_update(cpu_extra + __LOG_BUF_LEN); +} +#else /* !CONFIG_SMP */ +static inline void log_buf_add_cpu(void) {} +#endif /* CONFIG_SMP */ + +void __init setup_log_buf(int early) +{ + unsigned long flags; + char *new_log_buf; + int free; + + if (log_buf != __log_buf) + return; + + if (!early && !new_log_buf_len) + log_buf_add_cpu(); + + if (!new_log_buf_len) + return; + + if (early) { + new_log_buf = + memblock_virt_alloc(new_log_buf_len, LOG_ALIGN); + } else { + new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, + LOG_ALIGN); + } + + 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 bytes\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 = true; + pr_info("debug: ignoring loglevel setting.\n"); + + return 0; +} + +early_param("ignore_loglevel", ignore_loglevel_setup); +module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(ignore_loglevel, + "ignore loglevel setting (prints all kernel messages to the console)"); + +#ifdef CONFIG_BOOT_PRINTK_DELAY + +static int boot_delay; /* msecs delay after each printk during bootup */ +static unsigned long long loops_per_msec; /* based on boot_delay */ + +static int __init boot_delay_setup(char *str) +{ + unsigned long lpj; + + lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ + loops_per_msec = (unsigned long long)lpj / 1000 * HZ; + + get_option(&str, &boot_delay); + if (boot_delay > 10 * 1000) + boot_delay = 0; + + pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " + "HZ: %d, loops_per_msec: %llu\n", + boot_delay, preset_lpj, lpj, HZ, loops_per_msec); + return 0; +} +early_param("boot_delay", boot_delay_setup); + +static void boot_delay_msec(int level) +{ + unsigned long long k; + unsigned long timeout; + + if ((boot_delay == 0 || system_state != SYSTEM_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 + +static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); +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 printk_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 printk_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 printk_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 printk_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 printk_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; + while (len >= 0 && seq < next_seq) { + struct printk_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 = LOGLEVEL_DEFAULT; + int error; + + error = check_syslog_permissions(type, from_file); + if (error) + goto out; + + 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 == LOGLEVEL_DEFAULT) + saved_console_loglevel = console_loglevel; + console_loglevel = minimum_console_loglevel; + break; + /* Enable logging to console */ + case SYSLOG_ACTION_CONSOLE_ON: + if (saved_console_loglevel != LOGLEVEL_DEFAULT) { + console_loglevel = saved_console_loglevel; + saved_console_loglevel = LOGLEVEL_DEFAULT; + } + break; + /* Set level of messages printed to console */ + case SYSLOG_ACTION_CONSOLE_LEVEL: + 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 = LOGLEVEL_DEFAULT; + 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_seq - syslog_seq; + } else { + u64 seq = syslog_seq; + u32 idx = syslog_idx; + enum log_flags prev = syslog_prev; + + error = 0; + while (seq < log_next_seq) { + struct printk_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, level); + } +} + +/* + * Zap console related locks when oopsing. + * To leave time for slow consoles to print a full oops, + * only zap at most once every 30 seconds. + */ +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 that is capable of printing while cpu is + * booting or shutting down. Requires console_sem. + */ +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. + */ +static int console_trylock_for_printk(void) +{ + unsigned int cpu = smp_processor_id(); + + if (!console_trylock()) + return 0; + /* + * 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; + up_console_sem(); + return 0; + } + return 1; +} + +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 facility 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 = 0; + enum log_flags lflags = 0; + unsigned long flags; + int this_cpu; + int printed_len = 0; + bool in_sched = false; + /* cpu currently holding logbuf_lock in this function */ + static unsigned int logbuf_cpu = UINT_MAX; + + if (level == LOGLEVEL_SCHED) { + level = LOGLEVEL_DEFAULT; + in_sched = true; + } + + 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; + local_irq_restore(flags); + return 0; + } + zap_locks(); + } + + lockdep_off(); + raw_spin_lock(&logbuf_lock); + logbuf_cpu = this_cpu; + + if (unlikely(recursion_bug)) { + static const char recursion_msg[] = + "BUG: recent printk recursion!"; + + recursion_bug = 0; + /* emit KERN_CRIT message */ + printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0, + NULL, 0, recursion_msg, + strlen(recursion_msg)); + } + + /* + * 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 == LOGLEVEL_DEFAULT) + level = kern_level - '0'; + /* fallthrough */ + case 'd': /* KERN_DEFAULT */ + lflags |= LOG_PREFIX; + } + /* + * No need to check length here because vscnprintf + * put '\0' at the end of the string. Only valid and + * newly printed level is detected. + */ + text_len -= end_of_header - text; + text = (char *)end_of_header; + } + } + + if (level == LOGLEVEL_DEFAULT) + 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)) + printed_len += text_len; + else + printed_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 the preceding printk was from a different task and missed + * a newline, flush and append the newline. + */ + if (cont.len) { + if (cont.owner == current && !(lflags & LOG_PREFIX)) + stored = cont_add(facility, level, text, + text_len); + cont_flush(LOG_NEWLINE); + } + + if (stored) + printed_len += text_len; + else + printed_len += log_store(facility, level, lflags, 0, + dict, dictlen, text, text_len); + } + + logbuf_cpu = UINT_MAX; + raw_spin_unlock(&logbuf_lock); + lockdep_on(); + local_irq_restore(flags); + + /* If called from the scheduler, we can not call up(). */ + if (!in_sched) { + lockdep_off(); + /* + * Disable preemption to avoid being preempted while holding + * console_sem which would prevent anyone from printing to + * console + */ + preempt_disable(); + + /* + * Try to acquire and then immediately release the console + * semaphore. The release will print out buffers and wake up + * /dev/kmsg and syslog() users. + */ + if (console_trylock_for_printk()) + console_unlock(); + preempt_enable(); + lockdep_on(); + } + + return printed_len; +} +EXPORT_SYMBOL(vprintk_emit); + +asmlinkage int vprintk(const char *fmt, va_list args) +{ + return vprintk_emit(0, LOGLEVEL_DEFAULT, 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); + +int vprintk_default(const char *fmt, va_list args) +{ + int r; + +#ifdef CONFIG_KGDB_KDB + if (unlikely(kdb_trap_printk)) { + r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); + return r; + } +#endif + r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); + + return r; +} +EXPORT_SYMBOL_GPL(vprintk_default); + +/* + * This allows printk to be diverted to another function per cpu. + * This is useful for calling printk functions from within NMI + * without worrying about race conditions that can lock up the + * box. + */ +DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default; + +/** + * printk - print a kernel message + * @fmt: format string + * + * This is printk(). It can be called from any context. We want it to work. + * + * We try to grab the console_lock. If we succeed, it's easy - we log the + * output and call the console drivers. If we fail to get the semaphore, we + * place the output into the log buffer and return. The current holder of + * the console_sem will notice the new output in console_unlock(); and will + * send it to the consoles before releasing the lock. + * + * One effect of this deferred printing is that code which calls printk() and + * then changes console_loglevel may break. This is because console_loglevel + * is inspected when the actual printing occurs. + * + * See also: + * printf(3) + * + * See the vsnprintf() documentation for format string extensions over C99. + */ +asmlinkage __visible int printk(const char *fmt, ...) +{ + printk_func_t vprintk_func; + va_list args; + int r; + + va_start(args, fmt); + + /* + * If a caller overrides the per_cpu printk_func, then it needs + * to disable preemption when calling printk(). Otherwise + * the printk_func should be set to the default. No need to + * disable preemption here. + */ + vprintk_func = this_cpu_read(printk_func); + r = vprintk_func(fmt, args); + + va_end(args); + + return r; +} +EXPORT_SYMBOL(printk); + +#else /* CONFIG_PRINTK */ + +#define LOG_LINE_MAX 0 +#define PREFIX_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 printk_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 printk_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; } + +/* Still needs to be defined for users */ +DEFINE_PER_CPU(printk_func_t, printk_func); + +#endif /* CONFIG_PRINTK */ + +#ifdef CONFIG_EARLY_PRINTK +struct console *early_console; + +asmlinkage __visible void early_printk(const char *fmt, ...) +{ + va_list ap; + char buf[512]; + int n; + + if (!early_console) + return; + + va_start(ap, fmt); + n = vscnprintf(buf, sizeof(buf), fmt, ap); + va_end(ap); + + early_console->write(early_console, buf, n, 0); +} +#endif + +static int __add_preferred_console(char *name, int idx, char *options, + char *brl_options) +{ + struct console_cmdline *c; + int i; + + /* + * See if this tty is not yet registered, and + * if we have a slot free. + */ + for (i = 0, c = console_cmdline; + i < MAX_CMDLINECONSOLES && c->name[0]; + i++, c++) { + if (strcmp(c->name, name) == 0 && c->index == idx) { + if (!brl_options) + selected_console = i; + return 0; + } + } + if (i == MAX_CMDLINECONSOLES) + return -E2BIG; + if (!brl_options) + selected_console = i; + strlcpy(c->name, name, sizeof(c->name)); + c->options = options; + braille_set_options(c, brl_options); + + c->index = idx; + return 0; +} +/* + * Set up a console. Called via do_early_param() in init/main.c + * for each "console=" parameter in the boot command line. + */ +static int __init console_setup(char *str) +{ + char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ + char *s, *options, *brl_options = NULL; + int idx; + + if (_braille_console_setup(&str, &brl_options)) + return 1; + + /* + * Decode str into name, index, options. + */ + if (str[0] >= '0' && str[0] <= '9') { + strcpy(buf, "ttyS"); + strncpy(buf + 4, str, sizeof(buf) - 5); + } else { + strncpy(buf, str, sizeof(buf) - 1); + } + buf[sizeof(buf) - 1] = 0; + options = strchr(str, ','); + if (options) + *(options++) = 0; +#ifdef __sparc__ + if (!strcmp(str, "ttya")) + strcpy(buf, "ttyS0"); + if (!strcmp(str, "ttyb")) + strcpy(buf, "ttyS1"); +#endif + for (s = buf; *s; s++) + if (isdigit(*s) || *s == ',') + break; + idx = simple_strtoul(s, NULL, 10); + *s = 0; + + __add_preferred_console(buf, idx, options, brl_options); + console_set_on_cmdline = 1; + return 1; +} +__setup("console=", console_setup); + +/** + * add_preferred_console - add a device to the list of preferred consoles. + * @name: device name + * @idx: device index + * @options: options for this console + * + * The last preferred console added will be used for kernel messages + * and stdin/out/err for init. Normally this is used by console_setup + * above to handle user-supplied console arguments; however it can also + * be used by arch-specific code either to override the user or more + * commonly to provide a default console (ie from PROM variables) when + * the user has not supplied one. + */ +int add_preferred_console(char *name, int idx, char *options) +{ + return __add_preferred_console(name, idx, options, NULL); +} + +bool console_suspend_enabled = true; +EXPORT_SYMBOL(console_suspend_enabled); + +static int __init console_suspend_disable(char *str) +{ + console_suspend_enabled = false; + return 1; +} +__setup("no_console_suspend", console_suspend_disable); +module_param_named(console_suspend, console_suspend_enabled, + bool, S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(console_suspend, "suspend console during suspend" + " and hibernate operations"); + +/** + * suspend_console - suspend the console subsystem + * + * This disables printk() while we go into suspend states + */ +void suspend_console(void) +{ + if (!console_suspend_enabled) + return; + 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; +} +EXPORT_SYMBOL(console_lock); + +/** + * console_trylock - try to lock the console system for exclusive use. + * + * Try to acquire a lock which guarantees that the caller has exclusive + * access to the console system and the console_drivers list. + * + * returns 1 on success, and 0 on failure to acquire the lock. + */ +int console_trylock(void) +{ + if (down_trylock_console_sem()) + return 0; + if (console_suspended) { + up_console_sem(); + return 0; + } + console_locked = 1; + console_may_schedule = 0; + return 1; +} +EXPORT_SYMBOL(console_trylock); + +int is_console_locked(void) +{ + return console_locked; +} + +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 printk_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) { + len = sprintf(text, "** %u printk messages dropped ** ", + (unsigned)(log_first_seq - console_seq)); + + /* messages are gone, move to first one */ + console_seq = log_first_seq; + console_idx = log_first_idx; + console_prev = 0; + } else { + len = 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 + len, sizeof(text) - len); + 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; + + /* 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; + pr_info("debug: skip boot console de-registration.\n"); + + return 0; +} + +early_param("keep_bootcon", keep_bootcon_setup); + +/* + * The console driver calls this routine during kernel initialization + * to register the console printing procedure with printk() and to + * print any messages that were printed by the kernel before the + * console driver was initialized. + * + * This can happen pretty early during the boot process (because of + * early_printk) - sometimes before setup_arch() completes - be careful + * of what kernel features are used - they may not be initialised yet. + * + * There are two types of consoles - bootconsoles (early_printk) and + * "real" consoles (everything which is not a bootconsole) which are + * handled differently. + * - Any number of bootconsoles can be registered at any time. + * - As soon as a "real" console is registered, all bootconsoles + * will be unregistered automatically. + * - Once a "real" console is registered, any attempt to register a + * bootconsoles will be rejected + */ +void register_console(struct console *newcon) +{ + int i; + unsigned long flags; + struct console *bcon = NULL; + struct console_cmdline *c; + + if (console_drivers) + for_each_console(bcon) + if (WARN(bcon == newcon, + "console '%s%d' already registered\n", + bcon->name, bcon->index)) + return; + + /* + * before we register a new CON_BOOT console, make sure we don't + * already have a valid console + */ + if (console_drivers && newcon->flags & CON_BOOT) { + /* find the last or real console */ + for_each_console(bcon) { + if (!(bcon->flags & CON_BOOT)) { + pr_info("Too late to register bootconsole %s%d\n", + newcon->name, newcon->index); + return; + } + } + } + + if (console_drivers && console_drivers->flags & CON_BOOT) + bcon = console_drivers; + + if (preferred_console < 0 || bcon || !console_drivers) + preferred_console = selected_console; + + /* + * 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, c = console_cmdline; + i < MAX_CMDLINECONSOLES && c->name[0]; + i++, c++) { + if (!newcon->match || + newcon->match(newcon, c->name, c->index, c->options) != 0) { + /* default matching */ + BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); + if (strcmp(c->name, newcon->name) != 0) + continue; + if (newcon->index >= 0 && + newcon->index != c->index) + continue; + if (newcon->index < 0) + newcon->index = c->index; + + if (_braille_register_console(newcon, c)) + return; + + if (newcon->setup && + newcon->setup(newcon, c->options) != 0) + break; + } + + newcon->flags |= CON_ENABLED; + if (i == 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) + */ + pr_info("%sconsole [%s%d] enabled\n", + (newcon->flags & CON_BOOT) ? "boot" : "" , + newcon->name, newcon->index); + if (bcon && + ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && + !keep_bootcon) { + /* We need to iterate through all boot consoles, to make + * sure we print everything out, before we unregister them. + */ + for_each_console(bcon) + if (bcon->flags & CON_BOOT) + unregister_console(bcon); + } +} +EXPORT_SYMBOL(register_console); + +int unregister_console(struct console *console) +{ + struct console *a, *b; + int res; + + pr_info("%sconsole [%s%d] disabled\n", + (console->flags & CON_BOOT) ? "boot" : "" , + console->name, console->index); + + res = _braille_unregister_console(console); + if (res) + return res; + + res = 1; + console_lock(); + if (console_drivers == console) { + console_drivers=console->next; + res = 0; + } else if (console_drivers) { + for (a=console_drivers->next, b=console_drivers ; + a; b=a, a=b->next) { + if (a == console) { + b->next = a->next; + res = 0; + break; + } + } + } + + /* + * If this isn't the last console and it has CON_CONSDEV set, we + * need to set it on the next preferred console. + */ + if (console_drivers != NULL && console->flags & CON_CONSDEV) + console_drivers->flags |= CON_CONSDEV; + + console->flags &= ~CON_ENABLED; + console_unlock(); + console_sysfs_notify(); + return res; +} +EXPORT_SYMBOL(unregister_console); + +static int __init printk_late_init(void) +{ + struct console *con; + + for_each_console(con) { + if (!keep_bootcon && con->flags & CON_BOOT) { + 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_PENDING_WAKEUP 0x01 +#define PRINTK_PENDING_OUTPUT 0x02 + +static DEFINE_PER_CPU(int, printk_pending); + +static void wake_up_klogd_work_func(struct irq_work *irq_work) +{ + int pending = __this_cpu_xchg(printk_pending, 0); + + if (pending & PRINTK_PENDING_OUTPUT) { + /* If trylock fails, someone else is doing the printing */ + if (console_trylock()) + console_unlock(); + } + + 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(this_cpu_ptr(&wake_up_klogd_work)); + } + preempt_enable(); +} + +int printk_deferred(const char *fmt, ...) +{ + va_list args; + int r; + + preempt_disable(); + va_start(args, fmt); + r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); + va_end(args); + + __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); + irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); + preempt_enable(); + + return r; +} + +/* + * printk rate limiting, lifted from the networking subsystem. + * + * This enforces a rate limit: not more than 10 kernel messages + * every 5s to make a denial-of-service attack impossible. + */ +DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); + +int __printk_ratelimit(const char *func) +{ + return ___ratelimit(&printk_ratelimit_state, func); +} +EXPORT_SYMBOL(__printk_ratelimit); + +/** + * printk_timed_ratelimit - caller-controlled printk ratelimiting + * @caller_jiffies: pointer to caller's state + * @interval_msecs: minimum interval between prints + * + * printk_timed_ratelimit() returns true if more than @interval_msecs + * milliseconds have elapsed since the last time printk_timed_ratelimit() + * returned true. + */ +bool printk_timed_ratelimit(unsigned long *caller_jiffies, + unsigned int interval_msecs) +{ + unsigned long elapsed = jiffies - *caller_jiffies; + + if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) + return false; + + *caller_jiffies = jiffies; + return true; +} +EXPORT_SYMBOL(printk_timed_ratelimit); + +static DEFINE_SPINLOCK(dump_list_lock); +static LIST_HEAD(dump_list); + +/** + * kmsg_dump_register - register a kernel log dumper. + * @dumper: pointer to the kmsg_dumper structure + * + * Adds a kernel log dumper to the system. The dump callback in the + * structure will be called when the kernel oopses or panics and must be + * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. + */ +int kmsg_dump_register(struct kmsg_dumper *dumper) +{ + unsigned long flags; + int err = -EBUSY; + + /* The dump callback needs to be set */ + if (!dumper->dump) + return -EINVAL; + + spin_lock_irqsave(&dump_list_lock, flags); + /* Don't allow registering multiple times */ + if (!dumper->registered) { + dumper->registered = 1; + list_add_tail_rcu(&dumper->list, &dump_list); + err = 0; + } + spin_unlock_irqrestore(&dump_list_lock, flags); + + return err; +} +EXPORT_SYMBOL_GPL(kmsg_dump_register); + +/** + * kmsg_dump_unregister - unregister a kmsg dumper. + * @dumper: pointer to the kmsg_dumper structure + * + * Removes a dump device from the system. Returns zero on success and + * %-EINVAL otherwise. + */ +int kmsg_dump_unregister(struct kmsg_dumper *dumper) +{ + unsigned long flags; + int err = -EINVAL; + + spin_lock_irqsave(&dump_list_lock, flags); + if (dumper->registered) { + dumper->registered = 0; + list_del_rcu(&dumper->list); + err = 0; + } + spin_unlock_irqrestore(&dump_list_lock, flags); + synchronize_rcu(); + + return err; +} +EXPORT_SYMBOL_GPL(kmsg_dump_unregister); + +static bool always_kmsg_dump; +module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); + +/** + * kmsg_dump - dump kernel log to kernel message dumpers. + * @reason: the reason (oops, panic etc) for dumping + * + * Call each of the registered dumper's dump() callback, which can + * retrieve the kmsg records with kmsg_dump_get_line() or + * kmsg_dump_get_buffer(). + */ +void kmsg_dump(enum kmsg_dump_reason reason) +{ + struct kmsg_dumper *dumper; + 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 printk_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 printk_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 printk_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; + while (seq < dumper->next_seq) { + struct printk_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 |