| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/kernel/printk.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * |
| * Modified to make sys_syslog() more flexible: added commands to |
| * return the last 4k of kernel messages, regardless of whether |
| * they've been read or not. Added option to suppress kernel printk's |
| * to the console. Added hook for sending the console messages |
| * elsewhere, in preparation for a serial line console (someday). |
| * Ted Ts'o, 2/11/93. |
| * Modified for sysctl support, 1/8/97, Chris Horn. |
| * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
| * manfred@colorfullife.com |
| * Rewrote bits to get rid of console_lock |
| * 01Mar01 Andrew Morton |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <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/delay.h> |
| #include <linux/smp.h> |
| #include <linux/security.h> |
| #include <linux/memblock.h> |
| #include <linux/syscalls.h> |
| #include <linux/crash_core.h> |
| #include <linux/kdb.h> |
| #include <linux/ratelimit.h> |
| #include <linux/kmsg_dump.h> |
| #include <linux/syslog.h> |
| #include <linux/cpu.h> |
| #include <linux/rculist.h> |
| #include <linux/poll.h> |
| #include <linux/irq_work.h> |
| #include <linux/ctype.h> |
| #include <linux/uio.h> |
| #include <linux/sched/clock.h> |
| #include <linux/sched/debug.h> |
| #include <linux/sched/task_stack.h> |
| |
| #include <linux/uaccess.h> |
| #include <asm/sections.h> |
| |
| #include <trace/events/initcall.h> |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/printk.h> |
| |
| #include "console_cmdline.h" |
| #include "braille.h" |
| #include "internal.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 */ |
| }; |
| EXPORT_SYMBOL_GPL(console_printk); |
| |
| atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); |
| EXPORT_SYMBOL(ignore_console_lock_warning); |
| |
| /* |
| * Low level drivers may need that to know if they can schedule in |
| * their unblank() callback or not. So let's export it. |
| */ |
| int oops_in_progress; |
| EXPORT_SYMBOL(oops_in_progress); |
| |
| /* |
| * console_sem protects the console_drivers list, and also |
| * provides serialisation for access to the entire console |
| * driver system. |
| */ |
| static DEFINE_SEMAPHORE(console_sem); |
| struct console *console_drivers; |
| EXPORT_SYMBOL_GPL(console_drivers); |
| |
| /* |
| * System may need to suppress printk message under certain |
| * circumstances, like after kernel panic happens. |
| */ |
| int __read_mostly suppress_printk; |
| |
| #ifdef CONFIG_LOCKDEP |
| static struct lockdep_map console_lock_dep_map = { |
| .name = "console_lock" |
| }; |
| #endif |
| |
| enum devkmsg_log_bits { |
| __DEVKMSG_LOG_BIT_ON = 0, |
| __DEVKMSG_LOG_BIT_OFF, |
| __DEVKMSG_LOG_BIT_LOCK, |
| }; |
| |
| enum devkmsg_log_masks { |
| DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), |
| DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), |
| DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), |
| }; |
| |
| /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ |
| #define DEVKMSG_LOG_MASK_DEFAULT 0 |
| |
| static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; |
| |
| static int __control_devkmsg(char *str) |
| { |
| size_t len; |
| |
| if (!str) |
| return -EINVAL; |
| |
| len = str_has_prefix(str, "on"); |
| if (len) { |
| devkmsg_log = DEVKMSG_LOG_MASK_ON; |
| return len; |
| } |
| |
| len = str_has_prefix(str, "off"); |
| if (len) { |
| devkmsg_log = DEVKMSG_LOG_MASK_OFF; |
| return len; |
| } |
| |
| len = str_has_prefix(str, "ratelimit"); |
| if (len) { |
| devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; |
| return len; |
| } |
| |
| return -EINVAL; |
| } |
| |
| static int __init control_devkmsg(char *str) |
| { |
| if (__control_devkmsg(str) < 0) |
| return 1; |
| |
| /* |
| * Set sysctl string accordingly: |
| */ |
| if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
| strcpy(devkmsg_log_str, "on"); |
| else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) |
| strcpy(devkmsg_log_str, "off"); |
| /* else "ratelimit" which is set by default. */ |
| |
| /* |
| * Sysctl cannot change it anymore. The kernel command line setting of |
| * this parameter is to force the setting to be permanent throughout the |
| * runtime of the system. This is a precation measure against userspace |
| * trying to be a smarta** and attempting to change it up on us. |
| */ |
| devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; |
| |
| return 0; |
| } |
| __setup("printk.devkmsg=", control_devkmsg); |
| |
| char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; |
| |
| int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| char old_str[DEVKMSG_STR_MAX_SIZE]; |
| unsigned int old; |
| int err; |
| |
| if (write) { |
| if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) |
| return -EINVAL; |
| |
| old = devkmsg_log; |
| strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); |
| } |
| |
| err = proc_dostring(table, write, buffer, lenp, ppos); |
| if (err) |
| return err; |
| |
| if (write) { |
| err = __control_devkmsg(devkmsg_log_str); |
| |
| /* |
| * Do not accept an unknown string OR a known string with |
| * trailing crap... |
| */ |
| if (err < 0 || (err + 1 != *lenp)) { |
| |
| /* ... and restore old setting. */ |
| devkmsg_log = old; |
| strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); |
| |
| return -EINVAL; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* Number of registered extended console drivers. */ |
| static int nr_ext_console_drivers; |
| |
| /* |
| * Helper macros to handle lockdep when locking/unlocking console_sem. We use |
| * macros instead of functions so that _RET_IP_ contains useful information. |
| */ |
| #define down_console_sem() do { \ |
| down(&console_sem);\ |
| mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ |
| } while (0) |
| |
| static int __down_trylock_console_sem(unsigned long ip) |
| { |
| int lock_failed; |
| unsigned long flags; |
| |
| /* |
| * Here and in __up_console_sem() we need to be in safe mode, |
| * because spindump/WARN/etc from under console ->lock will |
| * deadlock in printk()->down_trylock_console_sem() otherwise. |
| */ |
| printk_safe_enter_irqsave(flags); |
| lock_failed = down_trylock(&console_sem); |
| printk_safe_exit_irqrestore(flags); |
| |
| if (lock_failed) |
| return 1; |
| mutex_acquire(&console_lock_dep_map, 0, 1, ip); |
| return 0; |
| } |
| #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) |
| |
| static void __up_console_sem(unsigned long ip) |
| { |
| unsigned long flags; |
| |
| mutex_release(&console_lock_dep_map, ip); |
| |
| printk_safe_enter_irqsave(flags); |
| up(&console_sem); |
| printk_safe_exit_irqrestore(flags); |
| } |
| #define up_console_sem() __up_console_sem(_RET_IP_) |
| |
| /* |
| * This is used for debugging the mess that is the VT code by |
| * keeping track if we have the console semaphore held. It's |
| * definitely not the perfect debug tool (we don't know if _WE_ |
| * hold it and are racing, but it helps tracking those weird code |
| * paths in the console code where we end up in places I want |
| * locked without the console sempahore held). |
| */ |
| static int console_locked, console_suspended; |
| |
| /* |
| * 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 preferred_console = -1; |
| int console_set_on_cmdline; |
| EXPORT_SYMBOL(console_set_on_cmdline); |
| |
| /* Flag: console code may call schedule() */ |
| static int console_may_schedule; |
| |
| enum con_msg_format_flags { |
| MSG_FORMAT_DEFAULT = 0, |
| MSG_FORMAT_SYSLOG = (1 << 0), |
| }; |
| |
| static int console_msg_format = MSG_FORMAT_DEFAULT; |
| |
| /* |
| * The printk log buffer consists of a chain of concatenated variable |
| * length records. Every record starts with a record header, containing |
| * the overall length of the record. |
| * |
| * The heads to the first and last entry in the buffer, as well as the |
| * sequence numbers of these entries are maintained when messages are |
| * stored. |
| * |
| * If the heads indicate available messages, the length in the header |
| * tells the start next message. A length == 0 for the next message |
| * indicates a wrap-around to the beginning of the buffer. |
| * |
| * Every record carries the monotonic timestamp in microseconds, as well as |
| * the standard userspace syslog level and syslog facility. The usual |
| * kernel messages use LOG_KERN; userspace-injected messages always carry |
| * a matching syslog facility, by default LOG_USER. The origin of every |
| * message can be reliably determined that way. |
| * |
| * The human readable log message directly follows the message header. The |
| * length of the message text is stored in the header, the stored message |
| * is not terminated. |
| * |
| * Optionally, a message can carry a dictionary of properties (key/value pairs), |
| * to provide userspace with a machine-readable message context. |
| * |
| * Examples for well-defined, commonly used property names are: |
| * DEVICE=b12:8 device identifier |
| * b12:8 block dev_t |
| * c127:3 char dev_t |
| * n8 netdev ifindex |
| * +sound:card0 subsystem:devname |
| * SUBSYSTEM=pci driver-core subsystem name |
| * |
| * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value |
| * follows directly after a '=' character. Every property is terminated by |
| * a '\0' character. The last property is not terminated. |
| * |
| * Example of a message structure: |
| * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec |
| * 0008 34 00 record is 52 bytes long |
| * 000a 0b 00 text is 11 bytes long |
| * 000c 1f 00 dictionary is 23 bytes long |
| * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) |
| * 0010 69 74 27 73 20 61 20 6c "it's a l" |
| * 69 6e 65 "ine" |
| * 001b 44 45 56 49 43 "DEVIC" |
| * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" |
| * 52 49 56 45 52 3d 62 75 "RIVER=bu" |
| * 67 "g" |
| * 0032 00 00 00 padding to next message header |
| * |
| * The 'struct printk_log' buffer header must never be directly exported to |
| * userspace, it is a kernel-private implementation detail that might |
| * need to be changed in the future, when the requirements change. |
| * |
| * /dev/kmsg exports the structured data in the following line format: |
| * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" |
| * |
| * Users of the export format should ignore possible additional values |
| * separated by ',', and find the message after the ';' character. |
| * |
| * The optional key/value pairs are attached as continuation lines starting |
| * with a space character and terminated by a newline. All possible |
| * non-prinatable characters are escaped in the "\xff" notation. |
| */ |
| |
| enum log_flags { |
| LOG_NEWLINE = 2, /* text ended with a newline */ |
| LOG_CONT = 8, /* text is a fragment of a continuation line */ |
| }; |
| |
| struct printk_log { |
| u64 ts_nsec; /* timestamp in nanoseconds */ |
| u16 len; /* length of entire record */ |
| u16 text_len; /* length of text buffer */ |
| u16 dict_len; /* length of dictionary buffer */ |
| u8 facility; /* syslog facility */ |
| u8 flags:5; /* internal record flags */ |
| u8 level:3; /* syslog level */ |
| #ifdef CONFIG_PRINTK_CALLER |
| u32 caller_id; /* thread id or processor id */ |
| #endif |
| } |
| #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
| __packed __aligned(4) |
| #endif |
| ; |
| |
| /* |
| * 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. |
| */ |
| DEFINE_RAW_SPINLOCK(logbuf_lock); |
| |
| /* |
| * Helper macros to lock/unlock logbuf_lock and switch between |
| * printk-safe/unsafe modes. |
| */ |
| #define logbuf_lock_irq() \ |
| do { \ |
| printk_safe_enter_irq(); \ |
| raw_spin_lock(&logbuf_lock); \ |
| } while (0) |
| |
| #define logbuf_unlock_irq() \ |
| do { \ |
| raw_spin_unlock(&logbuf_lock); \ |
| printk_safe_exit_irq(); \ |
| } while (0) |
| |
| #define logbuf_lock_irqsave(flags) \ |
| do { \ |
| printk_safe_enter_irqsave(flags); \ |
| raw_spin_lock(&logbuf_lock); \ |
| } while (0) |
| |
| #define logbuf_unlock_irqrestore(flags) \ |
| do { \ |
| raw_spin_unlock(&logbuf_lock); \ |
| printk_safe_exit_irqrestore(flags); \ |
| } while (0) |
| |
| #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 size_t syslog_partial; |
| static bool syslog_time; |
| |
| /* 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 u64 exclusive_console_stop_seq; |
| |
| /* the next printk record to read after the last 'clear' command */ |
| static u64 clear_seq; |
| static u32 clear_idx; |
| |
| #ifdef CONFIG_PRINTK_CALLER |
| #define PREFIX_MAX 48 |
| #else |
| #define PREFIX_MAX 32 |
| #endif |
| #define LOG_LINE_MAX (1024 - PREFIX_MAX) |
| |
| #define LOG_LEVEL(v) ((v) & 0x07) |
| #define LOG_FACILITY(v) ((v) >> 3 & 0xff) |
| |
| /* record buffer */ |
| #define LOG_ALIGN __alignof__(struct printk_log) |
| #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
| #define LOG_BUF_LEN_MAX (u32)(1 << 31) |
| static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
| static char *log_buf = __log_buf; |
| static u32 log_buf_len = __LOG_BUF_LEN; |
| |
| /* 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 && |
| !logbuf_has_space(msg_size, false)) { |
| /* drop old messages until we have enough contiguous space */ |
| log_first_idx = log_next(log_first_idx); |
| log_first_seq++; |
| } |
| |
| if (clear_seq < log_first_seq) { |
| clear_seq = log_first_seq; |
| clear_idx = log_first_idx; |
| } |
| |
| /* sequence numbers are equal, so the log buffer is empty */ |
| if (logbuf_has_space(msg_size, log_first_seq == log_next_seq)) |
| 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(u32 caller_id, 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(); |
| #ifdef CONFIG_PRINTK_CALLER |
| msg->caller_id = caller_id; |
| #endif |
| 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; |
| } |
| |
| static int check_syslog_permissions(int type, int source) |
| { |
| /* |
| * If this is from /proc/kmsg and we've already opened it, then we've |
| * already done the capabilities checks at open time. |
| */ |
| if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
| goto ok; |
| |
| if (syslog_action_restricted(type)) { |
| if (capable(CAP_SYSLOG)) |
| goto ok; |
| /* |
| * For historical reasons, accept CAP_SYS_ADMIN too, with |
| * a warning. |
| */ |
| if (capable(CAP_SYS_ADMIN)) { |
| pr_warn_once("%s (%d): Attempt to access syslog with " |
| "CAP_SYS_ADMIN but no CAP_SYSLOG " |
| "(deprecated).\n", |
| current->comm, task_pid_nr(current)); |
| goto ok; |
| } |
| return -EPERM; |
| } |
| ok: |
| return security_syslog(type); |
| } |
| |
| static void append_char(char **pp, char *e, char c) |
| { |
| if (*pp < e) |
| *(*pp)++ = c; |
| } |
| |
| static ssize_t msg_print_ext_header(char *buf, size_t size, |
| struct printk_log *msg, u64 seq) |
| { |
| u64 ts_usec = msg->ts_nsec; |
| char caller[20]; |
| #ifdef CONFIG_PRINTK_CALLER |
| u32 id = msg->caller_id; |
| |
| snprintf(caller, sizeof(caller), ",caller=%c%u", |
| id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); |
| #else |
| caller[0] = '\0'; |
| #endif |
| |
| do_div(ts_usec, 1000); |
| |
| return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", |
| (msg->facility << 3) | msg->level, seq, ts_usec, |
| msg->flags & LOG_CONT ? 'c' : '-', caller); |
| } |
| |
| static ssize_t msg_print_ext_body(char *buf, size_t size, |
| char *dict, size_t dict_len, |
| char *text, size_t text_len) |
| { |
| char *p = buf, *e = buf + size; |
| size_t i; |
| |
| /* escape non-printable characters */ |
| for (i = 0; i < text_len; i++) { |
| unsigned char c = text[i]; |
| |
| if (c < ' ' || c >= 127 || c == '\\') |
| p += scnprintf(p, e - p, "\\x%02x", c); |
| else |
| append_char(&p, e, c); |
| } |
| append_char(&p, e, '\n'); |
| |
| if (dict_len) { |
| bool line = true; |
| |
| for (i = 0; i < dict_len; i++) { |
| unsigned char c = dict[i]; |
| |
| if (line) { |
| append_char(&p, e, ' '); |
| line = false; |
| } |
| |
| if (c == '\0') { |
| append_char(&p, e, '\n'); |
| line = true; |
| continue; |
| } |
| |
| if (c < ' ' || c >= 127 || c == '\\') { |
| p += scnprintf(p, e - p, "\\x%02x", c); |
| continue; |
| } |
| |
| append_char(&p, e, c); |
| } |
| append_char(&p, e, '\n'); |
| } |
| |
| return p - buf; |
| } |
| |
| /* /dev/kmsg - userspace message inject/listen interface */ |
| struct devkmsg_user { |
| u64 seq; |
| u32 idx; |
| struct ratelimit_state rs; |
| struct mutex lock; |
| char buf[CONSOLE_EXT_LOG_MAX]; |
| }; |
| |
| static __printf(3, 4) __cold |
| int devkmsg_emit(int facility, int level, const char *fmt, ...) |
| { |
| va_list args; |
| int r; |
| |
| va_start(args, fmt); |
| r = vprintk_emit(facility, level, NULL, 0, fmt, args); |
| va_end(args); |
| |
| return r; |
| } |
| |
| static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
| { |
| char *buf, *line; |
| int level = default_message_loglevel; |
| int facility = 1; /* LOG_USER */ |
| struct file *file = iocb->ki_filp; |
| struct devkmsg_user *user = file->private_data; |
| size_t len = iov_iter_count(from); |
| ssize_t ret = len; |
| |
| if (!user || len > LOG_LINE_MAX) |
| return -EINVAL; |
| |
| /* Ignore when user logging is disabled. */ |
| if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
| return len; |
| |
| /* Ratelimit when not explicitly enabled. */ |
| if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { |
| if (!___ratelimit(&user->rs, current->comm)) |
| return ret; |
| } |
| |
| buf = kmalloc(len+1, GFP_KERNEL); |
| if (buf == NULL) |
| return -ENOMEM; |
| |
| buf[len] = '\0'; |
| if (!copy_from_iter_full(buf, len, from)) { |
| kfree(buf); |
| return -EFAULT; |
| } |
| |
| /* |
| * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace |
| * the decimal value represents 32bit, the lower 3 bit are the log |
| * level, the rest are the log facility. |
| * |
| * If no prefix or no userspace facility is specified, we |
| * enforce LOG_USER, to be able to reliably distinguish |
| * kernel-generated messages from userspace-injected ones. |
| */ |
| line = buf; |
| if (line[0] == '<') { |
| char *endp = NULL; |
| unsigned int u; |
| |
| u = simple_strtoul(line + 1, &endp, 10); |
| if (endp && endp[0] == '>') { |
| level = LOG_LEVEL(u); |
| if (LOG_FACILITY(u) != 0) |
| facility = LOG_FACILITY(u); |
| endp++; |
| len -= endp - line; |
| line = endp; |
| } |
| } |
| |
| devkmsg_emit(facility, level, "%s", line); |
| kfree(buf); |
| return ret; |
| } |
| |
| static ssize_t devkmsg_read(struct file *file, char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| struct devkmsg_user *user = file->private_data; |
| struct printk_log *msg; |
| size_t len; |
| ssize_t ret; |
| |
| if (!user) |
| return -EBADF; |
| |
| ret = mutex_lock_interruptible(&user->lock); |
| if (ret) |
| return ret; |
| |
| logbuf_lock_irq(); |
| while (user->seq == log_next_seq) { |
| if (file->f_flags & O_NONBLOCK) { |
| ret = -EAGAIN; |
| logbuf_unlock_irq(); |
| goto out; |
| } |
| |
| logbuf_unlock_irq(); |
| ret = wait_event_interruptible(log_wait, |
| user->seq != log_next_seq); |
| if (ret) |
| goto out; |
| logbuf_lock_irq(); |
| } |
| |
| 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; |
| logbuf_unlock_irq(); |
| goto out; |
| } |
| |
| msg = log_from_idx(user->idx); |
| len = msg_print_ext_header(user->buf, sizeof(user->buf), |
| msg, user->seq); |
| len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
| log_dict(msg), msg->dict_len, |
| log_text(msg), msg->text_len); |
| |
| user->idx = log_next(user->idx); |
| user->seq++; |
| logbuf_unlock_irq(); |
| |
| 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; |
| |
| logbuf_lock_irq(); |
| 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; |
| } |
| logbuf_unlock_irq(); |
| return ret; |
| } |
| |
| static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
| { |
| struct devkmsg_user *user = file->private_data; |
| __poll_t ret = 0; |
| |
| if (!user) |
| return EPOLLERR|EPOLLNVAL; |
| |
| poll_wait(file, &log_wait, wait); |
| |
| logbuf_lock_irq(); |
| if (user->seq < log_next_seq) { |
| /* return error when data has vanished underneath us */ |
| if (user->seq < log_first_seq) |
| ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
| else |
| ret = EPOLLIN|EPOLLRDNORM; |
| } |
| logbuf_unlock_irq(); |
| |
| return ret; |
| } |
| |
| static int devkmsg_open(struct inode *inode, struct file *file) |
| { |
| struct devkmsg_user *user; |
| int err; |
| |
| if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
| return -EPERM; |
| |
| /* write-only does not need any file context */ |
| if ((file->f_flags & O_ACCMODE) != O_WRONLY) { |
| err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, |
| SYSLOG_FROM_READER); |
| if (err) |
| return err; |
| } |
| |
| user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); |
| if (!user) |
| return -ENOMEM; |
| |
| ratelimit_default_init(&user->rs); |
| ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); |
| |
| mutex_init(&user->lock); |
| |
| logbuf_lock_irq(); |
| user->idx = log_first_idx; |
| user->seq = log_first_seq; |
| logbuf_unlock_irq(); |
| |
| file->private_data = user; |
| return 0; |
| } |
| |
| static int devkmsg_release(struct inode *inode, struct file *file) |
| { |
| struct devkmsg_user *user = file->private_data; |
| |
| if (!user) |
| return 0; |
| |
| ratelimit_state_exit(&user->rs); |
| |
| mutex_destroy(&user->lock); |
| kfree(user); |
| return 0; |
| } |
| |
| const struct file_operations kmsg_fops = { |
| .open = devkmsg_open, |
| .read = devkmsg_read, |
| .write_iter = devkmsg_write, |
| .llseek = devkmsg_llseek, |
| .poll = devkmsg_poll, |
| .release = devkmsg_release, |
| }; |
| |
| #ifdef CONFIG_CRASH_CORE |
| /* |
| * This appends the listed symbols to /proc/vmcore |
| * |
| * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
| * obtain access to symbols that are otherwise very difficult to locate. These |
| * symbols are specifically used so that utilities can access and extract the |
| * dmesg log from a vmcore file after a crash. |
| */ |
| void log_buf_vmcoreinfo_setup(void) |
| { |
| VMCOREINFO_SYMBOL(log_buf); |
| VMCOREINFO_SYMBOL(log_buf_len); |
| VMCOREINFO_SYMBOL(log_first_idx); |
| VMCOREINFO_SYMBOL(clear_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); |
| #ifdef CONFIG_PRINTK_CALLER |
| VMCOREINFO_OFFSET(printk_log, caller_id); |
| #endif |
| } |
| #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(u64 size) |
| { |
| if (size > (u64)LOG_BUF_LEN_MAX) { |
| size = (u64)LOG_BUF_LEN_MAX; |
| pr_err("log_buf over 2G is not supported.\n"); |
| } |
| |
| if (size) |
| size = roundup_pow_of_two(size); |
| if (size > log_buf_len) |
| new_log_buf_len = (unsigned long)size; |
| } |
| |
| /* save requested log_buf_len since it's too early to process it */ |
| static int __init log_buf_len_setup(char *str) |
| { |
| u64 size; |
| |
| if (!str) |
| return -EINVAL; |
| |
| size = memparse(str, &str); |
| |
| log_buf_len_update(size); |
| |
| return 0; |
| } |
| early_param("log_buf_len", log_buf_len_setup); |
| |
| #ifdef CONFIG_SMP |
| #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) |
| |
| static void __init log_buf_add_cpu(void) |
| { |
| unsigned int cpu_extra; |
| |
| /* |
| * archs should set up cpu_possible_bits properly with |
| * set_cpu_possible() after setup_arch() but just in |
| * case lets ensure this is valid. |
| */ |
| if (num_possible_cpus() == 1) |
| return; |
| |
| cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; |
| |
| /* by default this will only continue through for large > 64 CPUs */ |
| if (cpu_extra <= __LOG_BUF_LEN / 2) |
| return; |
| |
| pr_info("log_buf_len individual max cpu contribution: %d bytes\n", |
| __LOG_CPU_MAX_BUF_LEN); |
| pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", |
| cpu_extra); |
| pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); |
| |
| log_buf_len_update(cpu_extra + __LOG_BUF_LEN); |
| } |
| #else /* !CONFIG_SMP */ |
| static inline void log_buf_add_cpu(void) {} |
| #endif /* CONFIG_SMP */ |
| |
| void __init setup_log_buf(int early) |
| { |
| unsigned long flags; |
| char *new_log_buf; |
| unsigned int free; |
| |
| if (log_buf != __log_buf) |
| return; |
| |
| if (!early && !new_log_buf_len) |
| log_buf_add_cpu(); |
| |
| if (!new_log_buf_len) |
| return; |
| |
| new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN); |
| if (unlikely(!new_log_buf)) { |
| pr_err("log_buf_len: %lu bytes not available\n", |
| new_log_buf_len); |
| return; |
| } |
| |
| logbuf_lock_irqsave(flags); |
| log_buf_len = new_log_buf_len; |
| log_buf = new_log_buf; |
| new_log_buf_len = 0; |
| free = __LOG_BUF_LEN - log_next_idx; |
| memcpy(log_buf, __log_buf, __LOG_BUF_LEN); |
| logbuf_unlock_irqrestore(flags); |
| |
| pr_info("log_buf_len: %u bytes\n", log_buf_len); |
| pr_info("early log buf free: %u(%u%%)\n", |
| free, (free * 100) / __LOG_BUF_LEN); |
| } |
| |
| static bool __read_mostly ignore_loglevel; |
| |
| static int __init ignore_loglevel_setup(char *str) |
| { |
| ignore_loglevel = true; |
| pr_info("debug: ignoring loglevel setting.\n"); |
| |
| return 0; |
| } |
| |
| early_param("ignore_loglevel", ignore_loglevel_setup); |
| module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
| MODULE_PARM_DESC(ignore_loglevel, |
| "ignore loglevel setting (prints all kernel messages to the console)"); |
| |
| static bool suppress_message_printing(int level) |
| { |
| return (level >= console_loglevel && !ignore_loglevel); |
| } |
| |
| #ifdef CONFIG_BOOT_PRINTK_DELAY |
| |
| static int boot_delay; /* msecs delay after each printk during bootup */ |
| static unsigned long long loops_per_msec; /* based on boot_delay */ |
| |
| static int __init boot_delay_setup(char *str) |
| { |
| unsigned long lpj; |
| |
| lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
| loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
| |
| get_option(&str, &boot_delay); |
| if (boot_delay > 10 * 1000) |
| boot_delay = 0; |
| |
| pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
| "HZ: %d, loops_per_msec: %llu\n", |
| boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
| return 0; |
| } |
| early_param("boot_delay", boot_delay_setup); |
| |
| static void boot_delay_msec(int level) |
| { |
| unsigned long long k; |
| unsigned long timeout; |
| |
| if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
| || suppress_message_printing(level)) { |
| return; |
| } |
| |
| k = (unsigned long long)loops_per_msec * boot_delay; |
| |
| timeout = jiffies + msecs_to_jiffies(boot_delay); |
| while (k) { |
| k--; |
| cpu_relax(); |
| /* |
| * use (volatile) jiffies to prevent |
| * compiler reduction; loop termination via jiffies |
| * is secondary and may or may not happen. |
| */ |
| if (time_after(jiffies, timeout)) |
| break; |
| touch_nmi_watchdog(); |
| } |
| } |
| #else |
| static inline void boot_delay_msec(int level) |
| { |
| } |
| #endif |
| |
| static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
| module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
| |
| static size_t print_syslog(unsigned int level, char *buf) |
| { |
| return sprintf(buf, "<%u>", level); |
| } |
| |
| static size_t print_time(u64 ts, char *buf) |
| { |
| unsigned long rem_nsec = do_div(ts, 1000000000); |
| |
| return sprintf(buf, "[%5lu.%06lu]", |
| (unsigned long)ts, rem_nsec / 1000); |
| } |
| |
| #ifdef CONFIG_PRINTK_CALLER |
| static size_t print_caller(u32 id, char *buf) |
| { |
| char caller[12]; |
| |
| snprintf(caller, sizeof(caller), "%c%u", |
| id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); |
| return sprintf(buf, "[%6s]", caller); |
| } |
| #else |
| #define print_caller(id, buf) 0 |
| #endif |
| |
| static size_t print_prefix(const struct printk_log *msg, bool syslog, |
| bool time, char *buf) |
| { |
| size_t len = 0; |
| |
| if (syslog) |
| len = print_syslog((msg->facility << 3) | msg->level, buf); |
| |
| if (time) |
| len += print_time(msg->ts_nsec, buf + len); |
| |
| len += print_caller(msg->caller_id, buf + len); |
| |
| if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { |
| buf[len++] = ' '; |
| buf[len] = '\0'; |
| } |
| |
| return len; |
| } |
| |
| static size_t msg_print_text(const struct printk_log *msg, bool syslog, |
| bool time, char *buf, size_t size) |
| { |
| const char *text = log_text(msg); |
| size_t text_size = msg->text_len; |
| size_t len = 0; |
| char prefix[PREFIX_MAX]; |
| const size_t prefix_len = print_prefix(msg, syslog, time, prefix); |
| |
| do { |
| const char *next = memchr(text, '\n', text_size); |
| size_t text_len; |
| |
| if (next) { |
| text_len = next - text; |
| next++; |
| text_size -= next - text; |
| } else { |
| text_len = text_size; |
| } |
| |
| if (buf) { |
| if (prefix_len + text_len + 1 >= size - len) |
| break; |
| |
| memcpy(buf + len, prefix, prefix_len); |
| len += prefix_len; |
| memcpy(buf + len, text, text_len); |
| len += text_len; |
| buf[len++] = '\n'; |
| } else { |
| /* SYSLOG_ACTION_* buffer size only calculation */ |
| len += prefix_len + text_len + 1; |
| } |
| |
| text = next; |
| } while (text); |
| |
| return len; |
| } |
| |
| static int syslog_print(char __user *buf, int size) |
| { |
| char *text; |
| 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; |
| |
| logbuf_lock_irq(); |
| if (syslog_seq < log_first_seq) { |
| /* messages are gone, move to first one */ |
| syslog_seq = log_first_seq; |
| syslog_idx = log_first_idx; |
| syslog_partial = 0; |
| } |
| if (syslog_seq == log_next_seq) { |
| logbuf_unlock_irq(); |
| break; |
| } |
| |
| /* |
| * To keep reading/counting partial line consistent, |
| * use printk_time value as of the beginning of a line. |
| */ |
| if (!syslog_partial) |
| syslog_time = printk_time; |
| |
| skip = syslog_partial; |
| msg = log_from_idx(syslog_idx); |
| n = msg_print_text(msg, true, syslog_time, 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++; |
| n -= syslog_partial; |
| syslog_partial = 0; |
| } else if (!len){ |
| /* partial read(), remember position */ |
| n = size; |
| syslog_partial += n; |
| } else |
| n = 0; |
| logbuf_unlock_irq(); |
| |
| 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; |
| u64 next_seq; |
| u64 seq; |
| u32 idx; |
| bool time; |
| |
| text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
| if (!text) |
| return -ENOMEM; |
| |
| time = printk_time; |
| logbuf_lock_irq(); |
| /* |
| * 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 printk_log *msg = log_from_idx(idx); |
| |
| len += msg_print_text(msg, true, time, NULL, 0); |
| idx = log_next(idx); |
| seq++; |
| } |
| |
| /* move first record forward until length fits into the buffer */ |
| seq = clear_seq; |
| idx = clear_idx; |
| while (len > size && seq < log_next_seq) { |
| struct printk_log *msg = log_from_idx(idx); |
| |
| len -= msg_print_text(msg, true, time, NULL, 0); |
| 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 = msg_print_text(msg, true, time, text, |
| LOG_LINE_MAX + PREFIX_MAX); |
| |
| idx = log_next(idx); |
| seq++; |
| |
| logbuf_unlock_irq(); |
| if (copy_to_user(buf + len, text, textlen)) |
| len = -EFAULT; |
| else |
| len += textlen; |
| logbuf_lock_irq(); |
| |
| 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; |
| } |
| logbuf_unlock_irq(); |
| |
| kfree(text); |
| return len; |
| } |
| |
| static void syslog_clear(void) |
| { |
| logbuf_lock_irq(); |
| clear_seq = log_next_seq; |
| clear_idx = log_next_idx; |
| logbuf_unlock_irq(); |
| } |
| |
| int do_syslog(int type, char __user *buf, int len, int source) |
| { |
| bool clear = false; |
| static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
| int error; |
| |
| error = check_syslog_permissions(type, source); |
| if (error) |
| return error; |
| |
| switch (type) { |
| case SYSLOG_ACTION_CLOSE: /* Close log */ |
| break; |
| case SYSLOG_ACTION_OPEN: /* Open log */ |
| break; |
| case SYSLOG_ACTION_READ: /* Read from log */ |
| if (!buf || len < 0) |
| return -EINVAL; |
| if (!len) |
| return 0; |
| if (!access_ok(buf, len)) |
| return -EFAULT; |
| error = wait_event_interruptible(log_wait, |
| syslog_seq != log_next_seq); |
| if (error) |
| return error; |
| 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: |
| if (!buf || len < 0) |
| return -EINVAL; |
| if (!len) |
| return 0; |
| if (!access_ok(buf, len)) |
| return -EFAULT; |
| error = syslog_print_all(buf, len, clear); |
| break; |
| /* Clear ring buffer */ |
| case SYSLOG_ACTION_CLEAR: |
| syslog_clear(); |
| break; |
| /* Disable logging to console */ |
| case SYSLOG_ACTION_CONSOLE_OFF: |
| if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
| saved_console_loglevel = console_loglevel; |
| console_loglevel = minimum_console_loglevel; |
| break; |
| /* Enable logging to console */ |
| case SYSLOG_ACTION_CONSOLE_ON: |
| if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
| console_loglevel = saved_console_loglevel; |
| saved_console_loglevel = LOGLEVEL_DEFAULT; |
| } |
| break; |
| /* Set level of messages printed to console */ |
| case SYSLOG_ACTION_CONSOLE_LEVEL: |
| if (len < 1 || len > 8) |
| return -EINVAL; |
| if (len < minimum_console_loglevel) |
| len = minimum_console_loglevel; |
| console_loglevel = len; |
| /* Implicitly re-enable logging to console */ |
| saved_console_loglevel = LOGLEVEL_DEFAULT; |
| break; |
| /* Number of chars in the log buffer */ |
| case SYSLOG_ACTION_SIZE_UNREAD: |
| logbuf_lock_irq(); |
| if (syslog_seq < log_first_seq) { |
| /* messages are gone, move to first one */ |
| syslog_seq = log_first_seq; |
| syslog_idx = log_first_idx; |
| syslog_partial = 0; |
| } |
| if (source == SYSLOG_FROM_PROC) { |
| /* |
| * Short-cut for poll(/"proc/kmsg") which simply checks |
| * for pending data, not the size; return the count of |
| * records, not the length. |
| */ |
| error = log_next_seq - syslog_seq; |
| } else { |
| u64 seq = syslog_seq; |
| u32 idx = syslog_idx; |
| bool time = syslog_partial ? syslog_time : printk_time; |
| |
| while (seq < log_next_seq) { |
| struct printk_log *msg = log_from_idx(idx); |
| |
| error += msg_print_text(msg, true, time, NULL, |
| 0); |
| time = printk_time; |
| idx = log_next(idx); |
| seq++; |
| } |
| error -= syslog_partial; |
| } |
| logbuf_unlock_irq(); |
| break; |
| /* Size of the log buffer */ |
| case SYSLOG_ACTION_SIZE_BUFFER: |
| error = log_buf_len; |
| break; |
| default: |
| error = -EINVAL; |
| break; |
| } |
| |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
| { |
| return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
| } |
| |
| /* |
| * Special console_lock variants that help to reduce the risk of soft-lockups. |
| * They allow to pass console_lock to another printk() call using a busy wait. |
| */ |
| |
| #ifdef CONFIG_LOCKDEP |
| static struct lockdep_map console_owner_dep_map = { |
| .name = "console_owner" |
| }; |
| #endif |
| |
| static DEFINE_RAW_SPINLOCK(console_owner_lock); |
| static struct task_struct *console_owner; |
| static bool console_waiter; |
| |
| /** |
| * console_lock_spinning_enable - mark beginning of code where another |
| * thread might safely busy wait |
| * |
| * This basically converts console_lock into a spinlock. This marks |
| * the section where the console_lock owner can not sleep, because |
| * there may be a waiter spinning (like a spinlock). Also it must be |
| * ready to hand over the lock at the end of the section. |
| */ |
| static void console_lock_spinning_enable(void) |
| { |
| raw_spin_lock(&console_owner_lock); |
| console_owner = current; |
| raw_spin_unlock(&console_owner_lock); |
| |
| /* The waiter may spin on us after setting console_owner */ |
| spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); |
| } |
| |
| /** |
| * console_lock_spinning_disable_and_check - mark end of code where another |
| * thread was able to busy wait and check if there is a waiter |
| * |
| * This is called at the end of the section where spinning is allowed. |
| * It has two functions. First, it is a signal that it is no longer |
| * safe to start busy waiting for the lock. Second, it checks if |
| * there is a busy waiter and passes the lock rights to her. |
| * |
| * Important: Callers lose the lock if there was a busy waiter. |
| * They must not touch items synchronized by console_lock |
| * in this case. |
| * |
| * Return: 1 if the lock rights were passed, 0 otherwise. |
| */ |
| static int console_lock_spinning_disable_and_check(void) |
| { |
| int waiter; |
| |
| raw_spin_lock(&console_owner_lock); |
| waiter = READ_ONCE(console_waiter); |
| console_owner = NULL; |
| raw_spin_unlock(&console_owner_lock); |
| |
| if (!waiter) { |
| spin_release(&console_owner_dep_map, _THIS_IP_); |
| return 0; |
| } |
| |
| /* The waiter is now free to continue */ |
| WRITE_ONCE(console_waiter, false); |
| |
| spin_release(&console_owner_dep_map, _THIS_IP_); |
| |
| /* |
| * Hand off console_lock to waiter. The waiter will perform |
| * the up(). After this, the waiter is the console_lock owner. |
| */ |
| mutex_release(&console_lock_dep_map, _THIS_IP_); |
| return 1; |
| } |
| |
| /** |
| * console_trylock_spinning - try to get console_lock by busy waiting |
| * |
| * This allows to busy wait for the console_lock when the current |
| * owner is running in specially marked sections. It means that |
| * the current owner is running and cannot reschedule until it |
| * is ready to lose the lock. |
| * |
| * Return: 1 if we got the lock, 0 othrewise |
| */ |
| static int console_trylock_spinning(void) |
| { |
| struct task_struct *owner = NULL; |
| bool waiter; |
| bool spin = false; |
| unsigned long flags; |
| |
| if (console_trylock()) |
| return 1; |
| |
| printk_safe_enter_irqsave(flags); |
| |
| raw_spin_lock(&console_owner_lock); |
| owner = READ_ONCE(console_owner); |
| waiter = READ_ONCE(console_waiter); |
| if (!waiter && owner && owner != current) { |
| WRITE_ONCE(console_waiter, true); |
| spin = true; |
| } |
| raw_spin_unlock(&console_owner_lock); |
| |
| /* |
| * If there is an active printk() writing to the |
| * consoles, instead of having it write our data too, |
| * see if we can offload that load from the active |
| * printer, and do some printing ourselves. |
| * Go into a spin only if there isn't already a waiter |
| * spinning, and there is an active printer, and |
| * that active printer isn't us (recursive printk?). |
| */ |
| if (!spin) { |
| printk_safe_exit_irqrestore(flags); |
| return 0; |
| } |
| |
| /* We spin waiting for the owner to release us */ |
| spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); |
| /* Owner will clear console_waiter on hand off */ |
| while (READ_ONCE(console_waiter)) |
| cpu_relax(); |
| spin_release(&console_owner_dep_map, _THIS_IP_); |
| |
| printk_safe_exit_irqrestore(flags); |
| /* |
| * The owner passed the console lock to us. |
| * Since we did not spin on console lock, annotate |
| * this as a trylock. Otherwise lockdep will |
| * complain. |
| */ |
| mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); |
| |
| return 1; |
| } |
| |
| /* |
| * 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(const char *ext_text, size_t ext_len, |
| const char *text, size_t len) |
| { |
| struct console *con; |
| |
| trace_console_rcuidle(text, len); |
| |
| 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; |
| if (con->flags & CON_EXTENDED) |
| con->write(con, ext_text, ext_len); |
| else |
| con->write(con, text, len); |
| } |
| } |
| |
| 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(); |
| } |
| } |
| } |
| |
| static inline u32 printk_caller_id(void) |
| { |
| return in_task() ? task_pid_nr(current) : |
| 0x80000000 + raw_smp_processor_id(); |
| } |
| |
| /* |
| * Continuation lines are buffered, and not committed to the record buffer |
| * until the line is complete, or a race forces it. The line fragments |
| * though, are printed immediately to the consoles to ensure everything has |
| * reached the console in case of a kernel crash. |
| */ |
| static struct cont { |
| char buf[LOG_LINE_MAX]; |
| size_t len; /* length == 0 means unused buffer */ |
| u32 caller_id; /* printk_caller_id() of first print */ |
| u64 ts_nsec; /* time of first print */ |
| u8 level; /* log level of first message */ |
| u8 facility; /* log facility of first message */ |
| enum log_flags flags; /* prefix, newline flags */ |
| } cont; |
| |
| static void cont_flush(void) |
| { |
| if (cont.len == 0) |
| return; |
| |
| log_store(cont.caller_id, cont.facility, cont.level, cont.flags, |
| cont.ts_nsec, NULL, 0, cont.buf, cont.len); |
| cont.len = 0; |
| } |
| |
| static bool cont_add(u32 caller_id, int facility, int level, |
| enum log_flags flags, const char *text, size_t len) |
| { |
| /* If the line gets too long, split it up in separate records. */ |
| if (cont.len + len > sizeof(cont.buf)) { |
| cont_flush(); |
| return false; |
| } |
| |
| if (!cont.len) { |
| cont.facility = facility; |
| cont.level = level; |
| cont.caller_id = caller_id; |
| cont.ts_nsec = local_clock(); |
| cont.flags = flags; |
| } |
| |
| memcpy(cont.buf + cont.len, text, len); |
| cont.len += len; |
| |
| // The original flags come from the first line, |
| // but later continuations can add a newline. |
| if (flags & LOG_NEWLINE) { |
| cont.flags |= LOG_NEWLINE; |
| cont_flush(); |
| } |
| |
| return true; |
| } |
| |
| static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len) |
| { |
| const u32 caller_id = printk_caller_id(); |
| |
| /* |
| * If an earlier line was buffered, and we're a continuation |
| * write from the same context, try to add it to the buffer. |
| */ |
| if (cont.len) { |
| if (cont.caller_id == caller_id && (lflags & LOG_CONT)) { |
| if (cont_add(caller_id, facility, level, lflags, text, text_len)) |
| return text_len; |
| } |
| /* Otherwise, make sure it's flushed */ |
| cont_flush(); |
| } |
| |
| /* Skip empty continuation lines that couldn't be added - they just flush */ |
| if (!text_len && (lflags & LOG_CONT)) |
| return 0; |
| |
| /* If it doesn't end in a newline, try to buffer the current line */ |
| if (!(lflags & LOG_NEWLINE)) { |
| if (cont_add(caller_id, facility, level, lflags, text, text_len)) |
| return text_len; |
| } |
| |
| /* Store it in the record log */ |
| return log_store(caller_id, facility, level, lflags, 0, |
| dict, dictlen, text, text_len); |
| } |
| |
| /* Must be called under logbuf_lock. */ |
| int vprintk_store(int facility, int level, |
| const char *dict, size_t dictlen, |
| const char *fmt, va_list args) |
| { |
| static char textbuf[LOG_LINE_MAX]; |
| char *text = textbuf; |
| size_t text_len; |
| enum log_flags lflags = 0; |
| |
| /* |
| * 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; |
| |
| while ((kern_level = printk_get_level(text)) != 0) { |
| switch (kern_level) { |
| case '0' ... '7': |
| if (level == LOGLEVEL_DEFAULT) |
| level = kern_level - '0'; |
| break; |
| case 'c': /* KERN_CONT */ |
| lflags |= LOG_CONT; |
| } |
| |
| text_len -= 2; |
| text += 2; |
| } |
| } |
| |
| if (level == LOGLEVEL_DEFAULT) |
| level = default_message_loglevel; |
| |
| if (dict) |
| lflags |= LOG_NEWLINE; |
| |
| return log_output(facility, level, lflags, |
| dict, dictlen, text, text_len); |
| } |
| |
| asmlinkage int vprintk_emit(int facility, int level, |
| const char *dict, size_t dictlen, |
| const char *fmt, va_list args) |
| { |
| int printed_len; |
| bool in_sched = false, pending_output; |
| unsigned long flags; |
| u64 curr_log_seq; |
| |
| /* Suppress unimportant messages after panic happens */ |
| if (unlikely(suppress_printk)) |
| return 0; |
| |
| 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 */ |
| logbuf_lock_irqsave(flags); |
| curr_log_seq = log_next_seq; |
| printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args); |
| pending_output = (curr_log_seq != log_next_seq); |
| logbuf_unlock_irqrestore(flags); |
| |
| /* If called from the scheduler, we can not call up(). */ |
| if (!in_sched && pending_output) { |
| /* |
| * 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_spinning()) |
| console_unlock(); |
| preempt_enable(); |
| } |
| |
| if (pending_output) |
| wake_up_klogd(); |
| return printed_len; |
| } |
| EXPORT_SYMBOL(vprintk_emit); |
| |
| asmlinkage int vprintk(const char *fmt, va_list args) |
| { |
| return vprintk_func(fmt, args); |
| } |
| EXPORT_SYMBOL(vprintk); |
| |
| int vprintk_default(const char *fmt, va_list args) |
| { |
| int r; |
| |
| #ifdef CONFIG_KGDB_KDB |
| /* Allow to pass printk() to kdb but avoid a recursion. */ |
| if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) { |
| r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); |
| return r; |
| } |
| #endif |
| r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
| |
| return r; |
| } |
| EXPORT_SYMBOL_GPL(vprintk_default); |
| |
| /** |
| * printk - print a kernel message |
| * @fmt: format string |
| * |
| * This is printk(). It can be called from any context. We want it to work. |
| * |
| * We try to grab the console_lock. If we succeed, it's easy - we log the |
| * output and call the console drivers. If we fail to get the semaphore, we |
| * place the output into the log buffer and return. The current holder of |
| * the console_sem will notice the new output in console_unlock(); and will |
| * send it to the consoles before releasing the lock. |
| * |
| * One effect of this deferred printing is that code which calls printk() and |
| * then changes console_loglevel may break. This is because console_loglevel |
| * is inspected when the actual printing occurs. |
| * |
| * See also: |
| * printf(3) |
| * |
| * See the vsnprintf() documentation for format string extensions over C99. |
| */ |
| asmlinkage __visible int printk(const char *fmt, ...) |
| { |
| va_list args; |
| int r; |
| |
| va_start(args, fmt); |
| r = vprintk_func(fmt, args); |
| va_end(args); |
| |
| return r; |
| } |
| EXPORT_SYMBOL(printk); |
| |
| #else /* CONFIG_PRINTK */ |
| |
| #define LOG_LINE_MAX 0 |
| #define PREFIX_MAX 0 |
| #define printk_time false |
| |
| static u64 syslog_seq; |
| static u32 syslog_idx; |
| static u64 console_seq; |
| static u32 console_idx; |
| static u64 exclusive_console_stop_seq; |
| static u64 log_first_seq; |
| static u32 log_first_idx; |
| static u64 log_next_seq; |
| static char *log_text(const struct printk_log *msg) { return NULL; } |
| static char *log_dict(const struct printk_log *msg) { return NULL; } |
| static struct printk_log *log_from_idx(u32 idx) { return NULL; } |
| static u32 log_next(u32 idx) { return 0; } |
| static ssize_t msg_print_ext_header(char *buf, size_t size, |
| struct printk_log *msg, |
| u64 seq) { return 0; } |
| static ssize_t msg_print_ext_body(char *buf, size_t size, |
| char *dict, size_t dict_len, |
| char *text, size_t text_len) { return 0; } |
| static void console_lock_spinning_enable(void) { } |
| static int console_lock_spinning_disable_and_check(void) { return 0; } |
| static void call_console_drivers(const char *ext_text, size_t ext_len, |
| const char *text, size_t len) {} |
| static size_t msg_print_text(const struct printk_log *msg, bool syslog, |
| bool time, char *buf, size_t size) { return 0; } |
| static bool suppress_message_printing(int level) { return false; } |
| |
| #endif /* CONFIG_PRINTK */ |
| |
| #ifdef CONFIG_EARLY_PRINTK |
| struct console *early_console; |
| |
| asmlinkage __visible void early_printk(const char *fmt, ...) |
| { |
| va_list ap; |
| char buf[512]; |
| int n; |
| |
| if (!early_console) |
| return; |
| |
| va_start(ap, fmt); |
| n = vscnprintf(buf, sizeof(buf), fmt, ap); |
| va_end(ap); |
| |
| early_console->write(early_console, buf, n); |
| } |
| #endif |
| |
| static int __add_preferred_console(char *name, int idx, char *options, |
| char *brl_options) |
| { |
| struct console_cmdline *c; |
| int i; |
| |
| /* |
| * See if this tty is not yet registered, and |
| * if we have a slot free. |
| */ |
| for (i = 0, c = console_cmdline; |
| i < MAX_CMDLINECONSOLES && c->name[0]; |
| i++, c++) { |
| if (strcmp(c->name, name) == 0 && c->index == idx) { |
| if (!brl_options) |
| preferred_console = i; |
| return 0; |
| } |
| } |
| if (i == MAX_CMDLINECONSOLES) |
| return -E2BIG; |
| if (!brl_options) |
| preferred_console = i; |
| strlcpy(c->name, name, sizeof(c->name)); |
| c->options = options; |
| braille_set_options(c, brl_options); |
| |
| c->index = idx; |
| return 0; |
| } |
| |
| static int __init console_msg_format_setup(char *str) |
| { |
| if (!strcmp(str, "syslog")) |
| console_msg_format = MSG_FORMAT_SYSLOG; |
| if (!strcmp(str, "default")) |
| console_msg_format = MSG_FORMAT_DEFAULT; |
| return 1; |
| } |
| __setup("console_msg_format=", console_msg_format_setup); |
| |
| /* |
| * Set up a console. Called via do_early_param() in init/main.c |
| * for each "console=" parameter in the boot command line. |
| */ |
| static int __init console_setup(char *str) |
| { |
| char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
| char *s, *options, *brl_options = NULL; |
| int idx; |
| |
| if (_braille_console_setup(&str, &brl_options)) |
| return 1; |
| |
| /* |
| * Decode str into name, index, options. |
| */ |
| if (str[0] >= '0' && str[0] <= '9') { |
| strcpy(buf, "ttyS"); |
| strncpy(buf + 4, str, sizeof(buf) - 5); |
| } else { |
| strncpy(buf, str, sizeof(buf) - 1); |
| } |
| buf[sizeof(buf) - 1] = 0; |
| options = strchr(str, ','); |
| if (options) |
| *(options++) = 0; |
| #ifdef __sparc__ |
| if (!strcmp(str, "ttya")) |
| strcpy(buf, "ttyS0"); |
| if (!strcmp(str, "ttyb")) |
| strcpy(buf, "ttyS1"); |
| #endif |
| for (s = buf; *s; s++) |
| if (isdigit(*s) || *s == ',') |
| break; |
| idx = simple_strtoul(s, NULL, 10); |
| *s = 0; |
| |
| __add_preferred_console(buf, idx, options, brl_options); |
| console_set_on_cmdline = 1; |
| return 1; |
| } |
| __setup("console=", console_setup); |
| |
| /** |
| * add_preferred_console - add a device to the list of preferred consoles. |
| * @name: device name |
| * @idx: device index |
| * @options: options for this console |
| * |
| * The last preferred console added will be used for kernel messages |
| * and stdin/out/err for init. Normally this is used by console_setup |
| * above to handle user-supplied console arguments; however it can also |
| * be used by arch-specific code either to override the user or more |
| * commonly to provide a default console (ie from PROM variables) when |
| * the user has not supplied one. |
| */ |
| int add_preferred_console(char *name, int idx, char *options) |
| { |
| return __add_preferred_console(name, idx, options, NULL); |
| } |
| |
| bool console_suspend_enabled = true; |
| EXPORT_SYMBOL(console_suspend_enabled); |
| |
| static int __init console_suspend_disable(char *str) |
| { |
| console_suspend_enabled = false; |
| return 1; |
| } |
| __setup("no_console_suspend", console_suspend_disable); |
| module_param_named(console_suspend, console_suspend_enabled, |
| bool, S_IRUGO | S_IWUSR); |
| MODULE_PARM_DESC(console_suspend, "suspend console during suspend" |
| " and hibernate operations"); |
| |
| /** |
| * suspend_console - suspend the console subsystem |
| * |
| * This disables printk() while we go into suspend states |
| */ |
| void suspend_console(void) |
| { |
| if (!console_suspend_enabled) |
| return; |
| pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
| console_lock(); |
| console_suspended = 1; |
| up_console_sem(); |
| } |
| |
| void resume_console(void) |
| { |
| if (!console_suspend_enabled) |
| return; |
| down_console_sem(); |
| console_suspended = 0; |
| console_unlock(); |
| } |
| |
| /** |
| * console_cpu_notify - print deferred console messages after CPU hotplug |
| * @cpu: unused |
| * |
| * If printk() is called from a CPU that is not online yet, the messages |
| * will be printed on the console only if there are CON_ANYTIME consoles. |
| * This function is called when a new CPU comes online (or fails to come |
| * up) or goes offline. |
| */ |
| static int console_cpu_notify(unsigned int cpu) |
| { |
| if (!cpuhp_tasks_frozen) { |
| /* If trylock fails, someone else is doing the printing */ |
| if (console_trylock()) |
| console_unlock(); |
| } |
| return 0; |
| } |
| |
| /** |
| * console_lock - lock the console system for exclusive use. |
| * |
| * Acquires a lock which guarantees that the caller has |
| * exclusive access to the console system and the console_drivers list. |
| * |
| * Can sleep, returns nothing. |
| */ |
| void console_lock(void) |
| { |
| might_sleep(); |
| |
| down_console_sem(); |
| if (console_suspended) |
| return; |
| console_locked = 1; |
| console_may_schedule = 1; |
| } |
| EXPORT_SYMBOL(console_lock); |
| |
| /** |
| * console_trylock - try to lock the console system for exclusive use. |
| * |
| * Try to acquire a lock which guarantees that the caller has exclusive |
| * access to the console system and the console_drivers list. |
| * |
| * returns 1 on success, and 0 on failure to acquire the lock. |
| */ |
| int console_trylock(void) |
| { |
| if (down_trylock_console_sem()) |
| return 0; |
| if (console_suspended) { |
| up_console_sem(); |
| return 0; |
| } |
| console_locked = 1; |
| console_may_schedule = 0; |
| return 1; |
| } |
| EXPORT_SYMBOL(console_trylock); |
| |
| int is_console_locked(void) |
| { |
| return console_locked; |
| } |
| EXPORT_SYMBOL(is_console_locked); |
| |
| /* |
| * 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_ENABLED) && |
| (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(void) |
| { |
| return cpu_online(raw_smp_processor_id()) || have_callable_console(); |
| } |
| |
| /** |
| * 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 ext_text[CONSOLE_EXT_LOG_MAX]; |
| static char text[LOG_LINE_MAX + PREFIX_MAX]; |
| unsigned long flags; |
| bool do_cond_resched, retry; |
| |
| if (console_suspended) { |
| up_console_sem(); |
| return; |
| } |
| |
| /* |
| * Console drivers are called with interrupts disabled, so |
| * @console_may_schedule should be cleared before; however, we may |
| * end up dumping a lot of lines, for example, if called from |
| * console registration path, and should invoke cond_resched() |
| * between lines if allowable. Not doing so can cause a very long |
| * scheduling stall on a slow console leading to RCU stall and |
| * softlockup warnings which exacerbate the issue with more |
| * messages practically incapacitating the system. |
| * |
| * console_trylock() is not able to detect the preemptive |
| * context reliably. Therefore the value must be stored before |
| * and cleared after the the "again" goto label. |
| */ |
| do_cond_resched = console_may_schedule; |
| again: |
| console_may_schedule = 0; |
| |
| /* |
| * We released the console_sem lock, so we need to recheck if |
| * cpu is online and (if not) is there at least one CON_ANYTIME |
| * console. |
| */ |
| if (!can_use_console()) { |
| console_locked = 0; |
| up_console_sem(); |
| return; |
| } |
| |
| for (;;) { |
| struct printk_log *msg; |
| size_t ext_len = 0; |
| size_t len; |
| |
| printk_safe_enter_irqsave(flags); |
| raw_spin_lock(&logbuf_lock); |
| if (console_seq < log_first_seq) { |
| len = sprintf(text, |
| "** %llu printk messages dropped **\n", |
| log_first_seq - console_seq); |
| |
| /* messages are gone, move to first one */ |
| console_seq = log_first_seq; |
| console_idx = log_first_idx; |
| } else { |
| len = 0; |
| } |
| skip: |
| if (console_seq == log_next_seq) |
| break; |
| |
| msg = log_from_idx(console_idx); |
| if (suppress_message_printing(msg->level)) { |
| /* |
| * Skip record we have buffered and already printed |
| * directly to the console when we received it, and |
| * record that has level above the console loglevel. |
| */ |
| console_idx = log_next(console_idx); |
| console_seq++; |
| goto skip; |
| } |
| |
| /* Output to all consoles once old messages replayed. */ |
| if (unlikely(exclusive_console && |
| console_seq >= exclusive_console_stop_seq)) { |
| exclusive_console = NULL; |
| } |
| |
| len += msg_print_text(msg, |
| console_msg_format & MSG_FORMAT_SYSLOG, |
| printk_time, text + len, sizeof(text) - len); |
| if (nr_ext_console_drivers) { |
| ext_len = msg_print_ext_header(ext_text, |
| sizeof(ext_text), |
| msg, console_seq); |
| ext_len += msg_print_ext_body(ext_text + ext_len, |
| sizeof(ext_text) - ext_len, |
| log_dict(msg), msg->dict_len, |
| log_text(msg), msg->text_len); |
| } |
| console_idx = log_next(console_idx); |
| console_seq++; |
| raw_spin_unlock(&logbuf_lock); |
| |
| /* |
| * While actively printing out messages, if another printk() |
| * were to occur on another CPU, it may wait for this one to |
| * finish. This task can not be preempted if there is a |
| * waiter waiting to take over. |
| */ |
| console_lock_spinning_enable(); |
| |
| stop_critical_timings(); /* don't trace print latency */ |
| call_console_drivers(ext_text, ext_len, text, len); |
| start_critical_timings(); |
| |
| if (console_lock_spinning_disable_and_check()) { |
| printk_safe_exit_irqrestore(flags); |
| return; |
| } |
| |
| printk_safe_exit_irqrestore(flags); |
| |
| if (do_cond_resched) |
| cond_resched(); |
| } |
| |
| console_locked = 0; |
| |
| 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(&logbuf_lock); |
| printk_safe_exit_irqrestore(flags); |
| |
| if (retry && console_trylock()) |
| goto again; |
| } |
| EXPORT_SYMBOL(console_unlock); |
| |
| /** |
| * console_conditional_schedule - yield the CPU if required |
| * |
| * If the console code is currently allowed to sleep, and |
| * if this CPU should yield the CPU to another task, do |
| * so here. |
| * |
| * Must be called within console_lock();. |
| */ |
| void __sched console_conditional_schedule(void) |
| { |
| if (console_may_schedule) |
| cond_resched(); |
| } |
| EXPORT_SYMBOL(console_conditional_schedule); |
| |
| void console_unblank(void) |
| { |
| struct console *c; |
| |
| /* |
| * console_unblank can no longer be called in interrupt context unless |
| * oops_in_progress is set to 1.. |
| */ |
| if (oops_in_progress) { |
| if (down_trylock_console_sem() != 0) |
| return; |
| } else |
| console_lock(); |
| |
| console_locked = 1; |
| console_may_schedule = 0; |
| for_each_console(c) |
| if ((c->flags & CON_ENABLED) && c->unblank) |
| c->unblank(); |
| console_unlock(); |
| } |
| |
| /** |
| * console_flush_on_panic - flush console content on panic |
| * @mode: flush all messages in buffer or just the pending ones |
| * |
| * Immediately output all pending messages no matter what. |
| */ |
| void console_flush_on_panic(enum con_flush_mode mode) |
| { |
| /* |
| * If someone else is holding the console lock, trylock will fail |
| * and may_schedule may be set. Ignore and proceed to unlock so |
| * that messages are flushed out. As this can be called from any |
| * context and we don't want to get preempted while flushing, |
| * ensure may_schedule is cleared. |
| */ |
| console_trylock(); |
| console_may_schedule = 0; |
| |
| if (mode == CONSOLE_REPLAY_ALL) { |
| unsigned long flags; |
| |
| logbuf_lock_irqsave(flags); |
| console_seq = log_first_seq; |
| console_idx = log_first_idx; |
| logbuf_unlock_irqrestore(flags); |
| } |
| 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; |
| static bool has_preferred; |
| |
| if (console_drivers) |
| for_each_console(bcon) |
| if (WARN(bcon == newcon, |
| "console '%s%d' already registered\n", |
| bcon->name, bcon->index)) |
| return; |
| |
| /* |
| * before we register a new CON_BOOT console, make sure we don't |
| * already have a valid console |
| */ |
| if (console_drivers && newcon->flags & CON_BOOT) { |
| /* find the last or real console */ |
| for_each_console(bcon) { |
| if (!(bcon->flags & CON_BOOT)) { |
| pr_info("Too late to register bootconsole %s%d\n", |
| newcon->name, newcon->index); |
| return; |
| } |
| } |
| } |
| |
| if (console_drivers && console_drivers->flags & CON_BOOT) |
| bcon = console_drivers; |
| |
| if (!has_preferred || bcon || !console_drivers) |
| has_preferred = preferred_console >= 0; |
| |
| /* |
| * See if we want to use this console driver. If we |
| * didn't select a console we take the first one |
| * that registers here. |
| */ |
| if (!has_preferred) { |
| if (newcon->index < 0) |
| newcon->index = 0; |
| if (newcon->setup == NULL || |
| newcon->setup(newcon, NULL) == 0) { |
| newcon->flags |= CON_ENABLED; |
| if (newcon->device) { |
| newcon->flags |= CON_CONSDEV; |
| has_preferred = true; |
| } |
| } |
| } |
| |
| /* |
| * See if this console matches one we selected on |
| * the command line. |
| */ |
| for (i = 0, c = console_cmdline; |
| i < MAX_CMDLINECONSOLES && c->name[0]; |
| i++, c++) { |
| if (!newcon->match || |
| newcon->match(newcon, c->name, c->index, c->options) != 0) { |
| /* default matching */ |
| BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); |
| if (strcmp(c->name, newcon->name) != 0) |
| continue; |
| if (newcon->index >= 0 && |
| newcon->index != c->index) |
| continue; |
| if (newcon->index < 0) |
| newcon->index = c->index; |
| |
| if (_braille_register_console(newcon, c)) |
| return; |
| |
| if (newcon->setup && |
| newcon->setup(newcon, c->options) != 0) |
| break; |
| } |
| |
| newcon->flags |= CON_ENABLED; |
| if (i == preferred_console) { |
| newcon->flags |= CON_CONSDEV; |
| has_preferred = true; |
| } |
| break; |
| } |
| |
| if (!(newcon->flags & CON_ENABLED)) |
| return; |
| |
| /* |
| * If we have a bootconsole, and are switching to a real console, |
| * don't print everything out again, since when the boot console, and |
| * the real console are the same physical device, it's annoying to |
| * see the beginning boot messages twice |
| */ |
| if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
| newcon->flags &= ~CON_PRINTBUFFER; |
| |
| /* |
| * Put this console in the list - keep the |
| * preferred driver at the head of the list. |
| */ |
| console_lock(); |
| if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
| newcon->next = console_drivers; |
| console_drivers = newcon; |
| if (newcon->next) |
| newcon->next->flags &= ~CON_CONSDEV; |
| } else { |
| newcon->next = console_drivers->next; |
| console_drivers->next = newcon; |
| } |
| |
| if (newcon->flags & CON_EXTENDED) |
| nr_ext_console_drivers++; |
| |
| if (newcon->flags & CON_PRINTBUFFER) { |
| /* |
| * console_unlock(); will print out the buffered messages |
| * for us. |
| */ |
| logbuf_lock_irqsave(flags); |
| console_seq = syslog_seq; |
| console_idx = syslog_idx; |
| /* |
| * 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. |
| * |
| * Set exclusive_console with disabled interrupts to reduce |
| * race window with eventual console_flush_on_panic() that |
| * ignores console_lock. |
| */ |
| exclusive_console = newcon; |
| exclusive_console_stop_seq = console_seq; |
| logbuf_unlock_irqrestore(flags); |
| } |
| 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 (!res && (console->flags & CON_EXTENDED)) |
| nr_ext_console_drivers--; |
| |
| /* |
| * If this isn't the last console and it has CON_CONSDEV set, we |
| * need to set it on the next preferred console. |
| */ |
| if (console_drivers != NULL && console->flags & CON_CONSDEV) |
| console_drivers->flags |= CON_CONSDEV; |
| |
| console->flags &= ~CON_ENABLED; |
| console_unlock(); |
| console_sysfs_notify(); |
| return res; |
| } |
| EXPORT_SYMBOL(unregister_console); |
| |
| /* |
| * Initialize the console device. This is called *early*, so |
| * we can't necessarily depend on lots of kernel help here. |
| * Just do some early initializations, and do the complex setup |
| * later. |
| */ |
| void __init console_init(void) |
| { |
| int ret; |
| initcall_t call; |
| initcall_entry_t *ce; |
| |
| /* Setup the default TTY line discipline. */ |
| n_tty_init(); |
| |
| /* |
| * set up the console device so that later boot sequences can |
| * inform about problems etc.. |
| */ |
| ce = __con_initcall_start; |
| trace_initcall_level("console"); |
| while (ce < __con_initcall_end) { |
| call = initcall_from_entry(ce); |
| trace_initcall_start(call); |
| ret = call(); |
| trace_initcall_finish(call, ret); |
| ce++; |
| } |
| } |
| |
| /* |
| * Some boot consoles access data that is in the init section and which will |
| * be discarded after the initcalls have been run. To make sure that no code |
| * will access this data, unregister the boot consoles in a late initcall. |
| * |
| * If for some reason, such as deferred probe or the driver being a loadable |
| * module, the real console hasn't registered yet at this point, there will |
| * be a brief interval in which no messages are logged to the console, which |
| * makes it difficult to diagnose problems that occur during this time. |
| * |
| * To mitigate this problem somewhat, only unregister consoles whose memory |
| * intersects with the init section. Note that all other boot consoles will |
| * get unregistred when the real preferred console is registered. |
| */ |
| static int __init printk_late_init(void) |
| { |
| struct console *con; |
| int ret; |
| |
| for_each_console(con) { |
| if (!(con->flags & CON_BOOT)) |
| continue; |
| |
| /* Check addresses that might be used for enabled consoles. */ |
| if (init_section_intersects(con, sizeof(*con)) || |
| init_section_contains(con->write, 0) || |
| init_section_contains(con->read, 0) || |
| init_section_contains(con->device, 0) || |
| init_section_contains(con->unblank, 0) || |
| init_section_contains(con->data, 0)) { |
| /* |
| * Please, consider moving the reported consoles out |
| * of the init section. |
| */ |
| pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
| con->name, con->index); |
| unregister_console(con); |
| } |
| } |
| ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
| console_cpu_notify); |
| WARN_ON(ret < 0); |
| ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", |
| console_cpu_notify, NULL); |
| WARN_ON(ret < 0); |
| return 0; |
| } |
| late_initcall(printk_late_init); |
| |
| #if defined CONFIG_PRINTK |
| /* |
| * 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(); |
| } |
| |
| void defer_console_output(void) |
| { |
| preempt_disable(); |
| __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
| irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
| preempt_enable(); |
| } |
| |
| int vprintk_deferred(const char *fmt, va_list args) |
| { |
| int r; |
| |
| r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); |
| defer_console_output(); |
| |
| return r; |
| } |
| |
| int printk_deferred(const char *fmt, ...) |
| { |
| va_list args; |
| int r; |
| |
| va_start(args, fmt); |
| r = vprintk_deferred(fmt, args); |
| va_end(args); |
| |
| return r; |
| } |
| |
| /* |
| * printk rate limiting, lifted from the networking subsystem. |
| * |
| * This enforces a rate limit: not more than 10 kernel messages |
| * every 5s to make a denial-of-service attack impossible. |
| */ |
| DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
| |
| int __printk_ratelimit(const char *func) |
| { |
| return ___ratelimit(&printk_ratelimit_state, func); |
| } |
| EXPORT_SYMBOL(__printk_ratelimit); |
| |
| /** |
| * printk_timed_ratelimit - caller-controlled printk ratelimiting |
| * @caller_jiffies: pointer to caller's state |
| * @interval_msecs: minimum interval between prints |
| * |
| * printk_timed_ratelimit() returns true if more than @interval_msecs |
| * milliseconds have elapsed since the last time printk_timed_ratelimit() |
| * returned true. |
| */ |
| bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
| unsigned int interval_msecs) |
| { |
| unsigned long elapsed = jiffies - *caller_jiffies; |
| |
| if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) |
| return false; |
| |
| *caller_jiffies = jiffies; |
| return true; |
| } |
| EXPORT_SYMBOL(printk_timed_ratelimit); |
| |
| static DEFINE_SPINLOCK(dump_list_lock); |
| static LIST_HEAD(dump_list); |
| |
| /** |
| * kmsg_dump_register - register a kernel log dumper. |
| * @dumper: pointer to the kmsg_dumper structure |
| * |
| * Adds a kernel log dumper to the system. The dump callback in the |
| * structure will be called when the kernel oopses or panics and must be |
| * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
| */ |
| int kmsg_dump_register(struct kmsg_dumper *dumper) |
| { |
| unsigned long flags; |
| int err = -EBUSY; |
| |
| /* The dump callback needs to be set */ |
| if (!dumper->dump) |
| return -EINVAL; |
| |
| spin_lock_irqsave(&dump_list_lock, flags); |
| /* Don't allow registering multiple times */ |
| if (!dumper->registered) { |
| dumper->registered = 1; |
| list_add_tail_rcu(&dumper->list, &dump_list); |
| err = 0; |
| } |
| spin_unlock_irqrestore(&dump_list_lock, flags); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(kmsg_dump_register); |
| |
| /** |
| * kmsg_dump_unregister - unregister a kmsg dumper. |
| * @dumper: pointer to the kmsg_dumper structure |
| * |
| * Removes a dump device from the system. Returns zero on success and |
| * %-EINVAL otherwise. |
| */ |
| int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
| { |
| unsigned long flags; |
| int err = -EINVAL; |
| |
| spin_lock_irqsave(&dump_list_lock, flags); |
| if (dumper->registered) { |
| dumper->registered = 0; |
| list_del_rcu(&dumper->list); |
| err = 0; |
| } |
| spin_unlock_irqrestore(&dump_list_lock, flags); |
| synchronize_rcu(); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
| |
| static bool always_kmsg_dump; |
| module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); |
| |
| /** |
| * kmsg_dump - dump kernel log to kernel message dumpers. |
| * @reason: the reason (oops, panic etc) for dumping |
| * |
| * Call each of the registered dumper's dump() callback, which can |
| * retrieve the kmsg records with kmsg_dump_get_line() or |
| * kmsg_dump_get_buffer(). |
| */ |
| void kmsg_dump(enum kmsg_dump_reason reason) |
| { |
| struct kmsg_dumper *dumper; |
| 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; |
| |
| logbuf_lock_irqsave(flags); |
| dumper->cur_seq = clear_seq; |
| dumper->cur_idx = clear_idx; |
| dumper->next_seq = log_next_seq; |
| dumper->next_idx = log_next_idx; |
| logbuf_unlock_irqrestore(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, syslog, printk_time, 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; |
| |
| logbuf_lock_irqsave(flags); |
| ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); |
| logbuf_unlock_irqrestore(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; |
| size_t l = 0; |
| bool ret = false; |
| bool time = printk_time; |
| |
| if (!dumper->active) |
| goto out; |
| |
| logbuf_lock_irqsave(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) { |
| logbuf_unlock_irqrestore(flags); |
| goto out; |
| } |
| |
| /* calculate length of entire buffer */ |
| seq = dumper->cur_seq; |
| idx = dumper->cur_idx; |
| while (seq < dumper->next_seq) { |
| struct printk_log *msg = log_from_idx(idx); |
| |
| l += msg_print_text(msg, true, time, NULL, 0); |
| idx = log_next(idx); |
| seq++; |
| } |
| |
| /* move first record forward until length fits into the buffer */ |
| seq = dumper->cur_seq; |
| idx = dumper->cur_idx; |
| while (l >= size && seq < dumper->next_seq) { |
| struct printk_log *msg = log_from_idx(idx); |
| |
| l -= msg_print_text(msg, true, time, NULL, 0); |
| idx = log_next(idx); |
| seq++; |
| } |
| |
| /* 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, syslog, time, buf + l, size - l); |
| idx = log_next(idx); |
| seq++; |
| } |
| |
| dumper->next_seq = next_seq; |
| dumper->next_idx = next_idx; |
| ret = true; |
| logbuf_unlock_irqrestore(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; |
| |
| logbuf_lock_irqsave(flags); |
| kmsg_dump_rewind_nolock(dumper); |
| logbuf_unlock_irqrestore(flags); |
| } |
| EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
| |
| #endif |