| // 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/vmcore_info.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 "printk_ringbuffer.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); |
| |
| EXPORT_TRACEPOINT_SYMBOL_GPL(console); |
| |
| /* |
| * 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_mutex protects console_list updates and console->flags updates. |
| * The flags are synchronized only for consoles that are registered, i.e. |
| * accessible via the console list. |
| */ |
| static DEFINE_MUTEX(console_mutex); |
| |
| /* |
| * console_sem protects updates to console->seq |
| * and also provides serialization for console printing. |
| */ |
| static DEFINE_SEMAPHORE(console_sem, 1); |
| HLIST_HEAD(console_list); |
| EXPORT_SYMBOL_GPL(console_list); |
| DEFINE_STATIC_SRCU(console_srcu); |
| |
| /* |
| * 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" |
| }; |
| |
| void lockdep_assert_console_list_lock_held(void) |
| { |
| lockdep_assert_held(&console_mutex); |
| } |
| EXPORT_SYMBOL(lockdep_assert_console_list_lock_held); |
| #endif |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| bool console_srcu_read_lock_is_held(void) |
| { |
| return srcu_read_lock_held(&console_srcu); |
| } |
| EXPORT_SYMBOL(console_srcu_read_lock_is_held); |
| #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) { |
| pr_warn("printk.devkmsg: bad option string '%s'\n", str); |
| return 1; |
| } |
| |
| /* |
| * Set sysctl string accordingly: |
| */ |
| if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
| strscpy(devkmsg_log_str, "on"); |
| else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) |
| strscpy(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 1; |
| } |
| __setup("printk.devkmsg=", control_devkmsg); |
| |
| char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; |
| #if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL) |
| int devkmsg_sysctl_set_loglvl(const struct ctl_table *table, int write, |
| void *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; |
| strscpy(old_str, devkmsg_log_str); |
| } |
| |
| 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; |
| strscpy(devkmsg_log_str, old_str); |
| |
| return -EINVAL; |
| } |
| } |
| |
| return 0; |
| } |
| #endif /* CONFIG_PRINTK && CONFIG_SYSCTL */ |
| |
| /** |
| * console_list_lock - Lock the console list |
| * |
| * For console list or console->flags updates |
| */ |
| void console_list_lock(void) |
| { |
| /* |
| * In unregister_console() and console_force_preferred_locked(), |
| * synchronize_srcu() is called with the console_list_lock held. |
| * Therefore it is not allowed that the console_list_lock is taken |
| * with the srcu_lock held. |
| * |
| * Detecting if this context is really in the read-side critical |
| * section is only possible if the appropriate debug options are |
| * enabled. |
| */ |
| WARN_ON_ONCE(debug_lockdep_rcu_enabled() && |
| srcu_read_lock_held(&console_srcu)); |
| |
| mutex_lock(&console_mutex); |
| } |
| EXPORT_SYMBOL(console_list_lock); |
| |
| /** |
| * console_list_unlock - Unlock the console list |
| * |
| * Counterpart to console_list_lock() |
| */ |
| void console_list_unlock(void) |
| { |
| mutex_unlock(&console_mutex); |
| } |
| EXPORT_SYMBOL(console_list_unlock); |
| |
| /** |
| * console_srcu_read_lock - Register a new reader for the |
| * SRCU-protected console list |
| * |
| * Use for_each_console_srcu() to iterate the console list |
| * |
| * Context: Any context. |
| * Return: A cookie to pass to console_srcu_read_unlock(). |
| */ |
| int console_srcu_read_lock(void) |
| { |
| return srcu_read_lock_nmisafe(&console_srcu); |
| } |
| EXPORT_SYMBOL(console_srcu_read_lock); |
| |
| /** |
| * console_srcu_read_unlock - Unregister an old reader from |
| * the SRCU-protected console list |
| * @cookie: cookie returned from console_srcu_read_lock() |
| * |
| * Counterpart to console_srcu_read_lock() |
| */ |
| void console_srcu_read_unlock(int cookie) |
| { |
| srcu_read_unlock_nmisafe(&console_srcu, cookie); |
| } |
| EXPORT_SYMBOL(console_srcu_read_unlock); |
| |
| /* |
| * 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_) |
| |
| static bool panic_in_progress(void) |
| { |
| return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID); |
| } |
| |
| /* Return true if a panic is in progress on the current CPU. */ |
| bool this_cpu_in_panic(void) |
| { |
| /* |
| * We can use raw_smp_processor_id() here because it is impossible for |
| * the task to be migrated to the panic_cpu, or away from it. If |
| * panic_cpu has already been set, and we're not currently executing on |
| * that CPU, then we never will be. |
| */ |
| return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id()); |
| } |
| |
| /* |
| * Return true if a panic is in progress on a remote CPU. |
| * |
| * On true, the local CPU should immediately release any printing resources |
| * that may be needed by the panic CPU. |
| */ |
| bool other_cpu_in_panic(void) |
| { |
| return (panic_in_progress() && !this_cpu_in_panic()); |
| } |
| |
| /* |
| * 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 semaphore held). |
| */ |
| static int console_locked; |
| |
| /* |
| * 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 sequenced collection of records, each |
| * containing variable length message text. Every record also contains its |
| * own meta-data (@info). |
| * |
| * Every record meta-data carries the 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 of a record is available in @text, the |
| * length of the message text in @text_len. The stored message is not |
| * terminated. |
| * |
| * Optionally, a record 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.-_]. Property names |
| * and values are terminated by a '\0' character. |
| * |
| * Example of record values: |
| * record.text_buf = "it's a line" (unterminated) |
| * record.info.seq = 56 |
| * record.info.ts_nsec = 36863 |
| * record.info.text_len = 11 |
| * record.info.facility = 0 (LOG_KERN) |
| * record.info.flags = 0 |
| * record.info.level = 3 (LOG_ERR) |
| * record.info.caller_id = 299 (task 299) |
| * record.info.dev_info.subsystem = "pci" (terminated) |
| * record.info.dev_info.device = "+pci:0000:00:01.0" (terminated) |
| * |
| * The 'struct printk_info' buffer 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. |
| */ |
| |
| /* syslog_lock protects syslog_* variables and write access to clear_seq. */ |
| static DEFINE_MUTEX(syslog_lock); |
| |
| #ifdef CONFIG_PRINTK |
| DECLARE_WAIT_QUEUE_HEAD(log_wait); |
| /* All 3 protected by @syslog_lock. */ |
| /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
| static u64 syslog_seq; |
| static size_t syslog_partial; |
| static bool syslog_time; |
| |
| struct latched_seq { |
| seqcount_latch_t latch; |
| u64 val[2]; |
| }; |
| |
| /* |
| * The next printk record to read after the last 'clear' command. There are |
| * two copies (updated with seqcount_latch) so that reads can locklessly |
| * access a valid value. Writers are synchronized by @syslog_lock. |
| */ |
| static struct latched_seq clear_seq = { |
| .latch = SEQCNT_LATCH_ZERO(clear_seq.latch), |
| .val[0] = 0, |
| .val[1] = 0, |
| }; |
| |
| #define LOG_LEVEL(v) ((v) & 0x07) |
| #define LOG_FACILITY(v) ((v) >> 3 & 0xff) |
| |
| /* record buffer */ |
| #define LOG_ALIGN __alignof__(unsigned long) |
| #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; |
| |
| /* |
| * Define the average message size. This only affects the number of |
| * descriptors that will be available. Underestimating is better than |
| * overestimating (too many available descriptors is better than not enough). |
| */ |
| #define PRB_AVGBITS 5 /* 32 character average length */ |
| |
| #if CONFIG_LOG_BUF_SHIFT <= PRB_AVGBITS |
| #error CONFIG_LOG_BUF_SHIFT value too small. |
| #endif |
| _DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS, |
| PRB_AVGBITS, &__log_buf[0]); |
| |
| static struct printk_ringbuffer printk_rb_dynamic; |
| |
| struct printk_ringbuffer *prb = &printk_rb_static; |
| |
| /* |
| * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before |
| * per_cpu_areas are initialised. This variable is set to true when |
| * it's safe to access per-CPU data. |
| */ |
| static bool __printk_percpu_data_ready __ro_after_init; |
| |
| bool printk_percpu_data_ready(void) |
| { |
| return __printk_percpu_data_ready; |
| } |
| |
| /* Must be called under syslog_lock. */ |
| static void latched_seq_write(struct latched_seq *ls, u64 val) |
| { |
| raw_write_seqcount_latch(&ls->latch); |
| ls->val[0] = val; |
| raw_write_seqcount_latch(&ls->latch); |
| ls->val[1] = val; |
| } |
| |
| /* Can be called from any context. */ |
| static u64 latched_seq_read_nolock(struct latched_seq *ls) |
| { |
| unsigned int seq; |
| unsigned int idx; |
| u64 val; |
| |
| do { |
| seq = raw_read_seqcount_latch(&ls->latch); |
| idx = seq & 0x1; |
| val = ls->val[idx]; |
| } while (raw_read_seqcount_latch_retry(&ls->latch, seq)); |
| |
| return val; |
| } |
| |
| /* 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; |
| } |
| |
| /* |
| * 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 void truncate_msg(u16 *text_len, u16 *trunc_msg_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 (if there is room) */ |
| *trunc_msg_len = strlen(trunc_msg); |
| if (*text_len >= *trunc_msg_len) |
| *text_len -= *trunc_msg_len; |
| else |
| *trunc_msg_len = 0; |
| } |
| |
| 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; |
| 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 info_print_ext_header(char *buf, size_t size, |
| struct printk_info *info) |
| { |
| u64 ts_usec = info->ts_nsec; |
| char caller[20]; |
| #ifdef CONFIG_PRINTK_CALLER |
| u32 id = info->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;", |
| (info->facility << 3) | info->level, info->seq, |
| ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller); |
| } |
| |
| static ssize_t msg_add_ext_text(char *buf, size_t size, |
| const char *text, size_t text_len, |
| unsigned char endc) |
| { |
| 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, endc); |
| |
| return p - buf; |
| } |
| |
| static ssize_t msg_add_dict_text(char *buf, size_t size, |
| const char *key, const char *val) |
| { |
| size_t val_len = strlen(val); |
| ssize_t len; |
| |
| if (!val_len) |
| return 0; |
| |
| len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */ |
| len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '='); |
| len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n'); |
| |
| return len; |
| } |
| |
| static ssize_t msg_print_ext_body(char *buf, size_t size, |
| char *text, size_t text_len, |
| struct dev_printk_info *dev_info) |
| { |
| ssize_t len; |
| |
| len = msg_add_ext_text(buf, size, text, text_len, '\n'); |
| |
| if (!dev_info) |
| goto out; |
| |
| len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM", |
| dev_info->subsystem); |
| len += msg_add_dict_text(buf + len, size - len, "DEVICE", |
| dev_info->device); |
| out: |
| return len; |
| } |
| |
| /* /dev/kmsg - userspace message inject/listen interface */ |
| struct devkmsg_user { |
| atomic64_t seq; |
| struct ratelimit_state rs; |
| struct mutex lock; |
| struct printk_buffers pbufs; |
| }; |
| |
| 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, 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 (len > PRINTKRB_RECORD_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++; |
| 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; |
| char *outbuf = &user->pbufs.outbuf[0]; |
| struct printk_message pmsg = { |
| .pbufs = &user->pbufs, |
| }; |
| ssize_t ret; |
| |
| ret = mutex_lock_interruptible(&user->lock); |
| if (ret) |
| return ret; |
| |
| if (!printk_get_next_message(&pmsg, atomic64_read(&user->seq), true, false)) { |
| if (file->f_flags & O_NONBLOCK) { |
| ret = -EAGAIN; |
| goto out; |
| } |
| |
| /* |
| * Guarantee this task is visible on the waitqueue before |
| * checking the wake condition. |
| * |
| * The full memory barrier within set_current_state() of |
| * prepare_to_wait_event() pairs with the full memory barrier |
| * within wq_has_sleeper(). |
| * |
| * This pairs with __wake_up_klogd:A. |
| */ |
| ret = wait_event_interruptible(log_wait, |
| printk_get_next_message(&pmsg, atomic64_read(&user->seq), true, |
| false)); /* LMM(devkmsg_read:A) */ |
| if (ret) |
| goto out; |
| } |
| |
| if (pmsg.dropped) { |
| /* our last seen message is gone, return error and reset */ |
| atomic64_set(&user->seq, pmsg.seq); |
| ret = -EPIPE; |
| goto out; |
| } |
| |
| atomic64_set(&user->seq, pmsg.seq + 1); |
| |
| if (pmsg.outbuf_len > count) { |
| ret = -EINVAL; |
| goto out; |
| } |
| |
| if (copy_to_user(buf, outbuf, pmsg.outbuf_len)) { |
| ret = -EFAULT; |
| goto out; |
| } |
| ret = pmsg.outbuf_len; |
| out: |
| mutex_unlock(&user->lock); |
| return ret; |
| } |
| |
| /* |
| * Be careful when modifying this function!!! |
| * |
| * Only few operations are supported because the device works only with the |
| * entire variable length messages (records). Non-standard values are |
| * returned in the other cases and has been this way for quite some time. |
| * User space applications might depend on this behavior. |
| */ |
| 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 (offset) |
| return -ESPIPE; |
| |
| switch (whence) { |
| case SEEK_SET: |
| /* the first record */ |
| atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
| 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. |
| */ |
| atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq)); |
| break; |
| case SEEK_END: |
| /* after the last record */ |
| atomic64_set(&user->seq, prb_next_seq(prb)); |
| break; |
| default: |
| ret = -EINVAL; |
| } |
| return ret; |
| } |
| |
| static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
| { |
| struct devkmsg_user *user = file->private_data; |
| struct printk_info info; |
| __poll_t ret = 0; |
| |
| poll_wait(file, &log_wait, wait); |
| |
| if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) { |
| /* return error when data has vanished underneath us */ |
| if (info.seq != atomic64_read(&user->seq)) |
| ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
| else |
| ret = EPOLLIN|EPOLLRDNORM; |
| } |
| |
| 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 = kvmalloc(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); |
| |
| atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
| |
| file->private_data = user; |
| return 0; |
| } |
| |
| static int devkmsg_release(struct inode *inode, struct file *file) |
| { |
| struct devkmsg_user *user = file->private_data; |
| |
| ratelimit_state_exit(&user->rs); |
| |
| mutex_destroy(&user->lock); |
| kvfree(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_VMCORE_INFO |
| /* |
| * 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) |
| { |
| struct dev_printk_info *dev_info = NULL; |
| |
| VMCOREINFO_SYMBOL(prb); |
| VMCOREINFO_SYMBOL(printk_rb_static); |
| VMCOREINFO_SYMBOL(clear_seq); |
| |
| /* |
| * Export struct size and field offsets. User space tools can |
| * parse it and detect any changes to structure down the line. |
| */ |
| |
| VMCOREINFO_STRUCT_SIZE(printk_ringbuffer); |
| VMCOREINFO_OFFSET(printk_ringbuffer, desc_ring); |
| VMCOREINFO_OFFSET(printk_ringbuffer, text_data_ring); |
| VMCOREINFO_OFFSET(printk_ringbuffer, fail); |
| |
| VMCOREINFO_STRUCT_SIZE(prb_desc_ring); |
| VMCOREINFO_OFFSET(prb_desc_ring, count_bits); |
| VMCOREINFO_OFFSET(prb_desc_ring, descs); |
| VMCOREINFO_OFFSET(prb_desc_ring, infos); |
| VMCOREINFO_OFFSET(prb_desc_ring, head_id); |
| VMCOREINFO_OFFSET(prb_desc_ring, tail_id); |
| |
| VMCOREINFO_STRUCT_SIZE(prb_desc); |
| VMCOREINFO_OFFSET(prb_desc, state_var); |
| VMCOREINFO_OFFSET(prb_desc, text_blk_lpos); |
| |
| VMCOREINFO_STRUCT_SIZE(prb_data_blk_lpos); |
| VMCOREINFO_OFFSET(prb_data_blk_lpos, begin); |
| VMCOREINFO_OFFSET(prb_data_blk_lpos, next); |
| |
| VMCOREINFO_STRUCT_SIZE(printk_info); |
| VMCOREINFO_OFFSET(printk_info, seq); |
| VMCOREINFO_OFFSET(printk_info, ts_nsec); |
| VMCOREINFO_OFFSET(printk_info, text_len); |
| VMCOREINFO_OFFSET(printk_info, caller_id); |
| VMCOREINFO_OFFSET(printk_info, dev_info); |
| |
| VMCOREINFO_STRUCT_SIZE(dev_printk_info); |
| VMCOREINFO_OFFSET(dev_printk_info, subsystem); |
| VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem)); |
| VMCOREINFO_OFFSET(dev_printk_info, device); |
| VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device)); |
| |
| VMCOREINFO_STRUCT_SIZE(prb_data_ring); |
| VMCOREINFO_OFFSET(prb_data_ring, size_bits); |
| VMCOREINFO_OFFSET(prb_data_ring, data); |
| VMCOREINFO_OFFSET(prb_data_ring, head_lpos); |
| VMCOREINFO_OFFSET(prb_data_ring, tail_lpos); |
| |
| VMCOREINFO_SIZE(atomic_long_t); |
| VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter); |
| |
| VMCOREINFO_STRUCT_SIZE(latched_seq); |
| VMCOREINFO_OFFSET(latched_seq, val); |
| } |
| #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 */ |
| |
| static void __init set_percpu_data_ready(void) |
| { |
| __printk_percpu_data_ready = true; |
| } |
| |
| static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, |
| struct printk_record *r) |
| { |
| struct prb_reserved_entry e; |
| struct printk_record dest_r; |
| |
| prb_rec_init_wr(&dest_r, r->info->text_len); |
| |
| if (!prb_reserve(&e, rb, &dest_r)) |
| return 0; |
| |
| memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len); |
| dest_r.info->text_len = r->info->text_len; |
| dest_r.info->facility = r->info->facility; |
| dest_r.info->level = r->info->level; |
| dest_r.info->flags = r->info->flags; |
| dest_r.info->ts_nsec = r->info->ts_nsec; |
| dest_r.info->caller_id = r->info->caller_id; |
| memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info)); |
| |
| prb_final_commit(&e); |
| |
| return prb_record_text_space(&e); |
| } |
| |
| static char setup_text_buf[PRINTKRB_RECORD_MAX] __initdata; |
| |
| void __init setup_log_buf(int early) |
| { |
| struct printk_info *new_infos; |
| unsigned int new_descs_count; |
| struct prb_desc *new_descs; |
| struct printk_info info; |
| struct printk_record r; |
| unsigned int text_size; |
| size_t new_descs_size; |
| size_t new_infos_size; |
| unsigned long flags; |
| char *new_log_buf; |
| unsigned int free; |
| u64 seq; |
| |
| /* |
| * Some archs call setup_log_buf() multiple times - first is very |
| * early, e.g. from setup_arch(), and second - when percpu_areas |
| * are initialised. |
| */ |
| if (!early) |
| set_percpu_data_ready(); |
| |
| if (log_buf != __log_buf) |
| return; |
| |
| if (!early && !new_log_buf_len) |
| log_buf_add_cpu(); |
| |
| if (!new_log_buf_len) |
| return; |
| |
| new_descs_count = new_log_buf_len >> PRB_AVGBITS; |
| if (new_descs_count == 0) { |
| pr_err("new_log_buf_len: %lu too small\n", 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 text bytes not available\n", |
| new_log_buf_len); |
| return; |
| } |
| |
| new_descs_size = new_descs_count * sizeof(struct prb_desc); |
| new_descs = memblock_alloc(new_descs_size, LOG_ALIGN); |
| if (unlikely(!new_descs)) { |
| pr_err("log_buf_len: %zu desc bytes not available\n", |
| new_descs_size); |
| goto err_free_log_buf; |
| } |
| |
| new_infos_size = new_descs_count * sizeof(struct printk_info); |
| new_infos = memblock_alloc(new_infos_size, LOG_ALIGN); |
| if (unlikely(!new_infos)) { |
| pr_err("log_buf_len: %zu info bytes not available\n", |
| new_infos_size); |
| goto err_free_descs; |
| } |
| |
| prb_rec_init_rd(&r, &info, &setup_text_buf[0], sizeof(setup_text_buf)); |
| |
| prb_init(&printk_rb_dynamic, |
| new_log_buf, ilog2(new_log_buf_len), |
| new_descs, ilog2(new_descs_count), |
| new_infos); |
| |
| local_irq_save(flags); |
| |
| log_buf_len = new_log_buf_len; |
| log_buf = new_log_buf; |
| new_log_buf_len = 0; |
| |
| free = __LOG_BUF_LEN; |
| prb_for_each_record(0, &printk_rb_static, seq, &r) { |
| text_size = add_to_rb(&printk_rb_dynamic, &r); |
| if (text_size > free) |
| free = 0; |
| else |
| free -= text_size; |
| } |
| |
| prb = &printk_rb_dynamic; |
| |
| local_irq_restore(flags); |
| |
| /* |
| * Copy any remaining messages that might have appeared from |
| * NMI context after copying but before switching to the |
| * dynamic buffer. |
| */ |
| prb_for_each_record(seq, &printk_rb_static, seq, &r) { |
| text_size = add_to_rb(&printk_rb_dynamic, &r); |
| if (text_size > free) |
| free = 0; |
| else |
| free -= text_size; |
| } |
| |
| if (seq != prb_next_seq(&printk_rb_static)) { |
| pr_err("dropped %llu messages\n", |
| prb_next_seq(&printk_rb_static) - seq); |
| } |
| |
| 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); |
| return; |
| |
| err_free_descs: |
| memblock_free(new_descs, new_descs_size); |
| err_free_log_buf: |
| memblock_free(new_log_buf, new_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 info_print_prefix(const struct printk_info *info, bool syslog, |
| bool time, char *buf) |
| { |
| size_t len = 0; |
| |
| if (syslog) |
| len = print_syslog((info->facility << 3) | info->level, buf); |
| |
| if (time) |
| len += print_time(info->ts_nsec, buf + len); |
| |
| len += print_caller(info->caller_id, buf + len); |
| |
| if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { |
| buf[len++] = ' '; |
| buf[len] = '\0'; |
| } |
| |
| return len; |
| } |
| |
| /* |
| * Prepare the record for printing. The text is shifted within the given |
| * buffer to avoid a need for another one. The following operations are |
| * done: |
| * |
| * - Add prefix for each line. |
| * - Drop truncated lines that no longer fit into the buffer. |
| * - Add the trailing newline that has been removed in vprintk_store(). |
| * - Add a string terminator. |
| * |
| * Since the produced string is always terminated, the maximum possible |
| * return value is @r->text_buf_size - 1; |
| * |
| * Return: The length of the updated/prepared text, including the added |
| * prefixes and the newline. The terminator is not counted. The dropped |
| * line(s) are not counted. |
| */ |
| static size_t record_print_text(struct printk_record *r, bool syslog, |
| bool time) |
| { |
| size_t text_len = r->info->text_len; |
| size_t buf_size = r->text_buf_size; |
| char *text = r->text_buf; |
| char prefix[PRINTK_PREFIX_MAX]; |
| bool truncated = false; |
| size_t prefix_len; |
| size_t line_len; |
| size_t len = 0; |
| char *next; |
| |
| /* |
| * If the message was truncated because the buffer was not large |
| * enough, treat the available text as if it were the full text. |
| */ |
| if (text_len > buf_size) |
| text_len = buf_size; |
| |
| prefix_len = info_print_prefix(r->info, syslog, time, prefix); |
| |
| /* |
| * @text_len: bytes of unprocessed text |
| * @line_len: bytes of current line _without_ newline |
| * @text: pointer to beginning of current line |
| * @len: number of bytes prepared in r->text_buf |
| */ |
| for (;;) { |
| next = memchr(text, '\n', text_len); |
| if (next) { |
| line_len = next - text; |
| } else { |
| /* Drop truncated line(s). */ |
| if (truncated) |
| break; |
| line_len = text_len; |
| } |
| |
| /* |
| * Truncate the text if there is not enough space to add the |
| * prefix and a trailing newline and a terminator. |
| */ |
| if (len + prefix_len + text_len + 1 + 1 > buf_size) { |
| /* Drop even the current line if no space. */ |
| if (len + prefix_len + line_len + 1 + 1 > buf_size) |
| break; |
| |
| text_len = buf_size - len - prefix_len - 1 - 1; |
| truncated = true; |
| } |
| |
| memmove(text + prefix_len, text, text_len); |
| memcpy(text, prefix, prefix_len); |
| |
| /* |
| * Increment the prepared length to include the text and |
| * prefix that were just moved+copied. Also increment for the |
| * newline at the end of this line. If this is the last line, |
| * there is no newline, but it will be added immediately below. |
| */ |
| len += prefix_len + line_len + 1; |
| if (text_len == line_len) { |
| /* |
| * This is the last line. Add the trailing newline |
| * removed in vprintk_store(). |
| */ |
| text[prefix_len + line_len] = '\n'; |
| break; |
| } |
| |
| /* |
| * Advance beyond the added prefix and the related line with |
| * its newline. |
| */ |
| text += prefix_len + line_len + 1; |
| |
| /* |
| * The remaining text has only decreased by the line with its |
| * newline. |
| * |
| * Note that @text_len can become zero. It happens when @text |
| * ended with a newline (either due to truncation or the |
| * original string ending with "\n\n"). The loop is correctly |
| * repeated and (if not truncated) an empty line with a prefix |
| * will be prepared. |
| */ |
| text_len -= line_len + 1; |
| } |
| |
| /* |
| * If a buffer was provided, it will be terminated. Space for the |
| * string terminator is guaranteed to be available. The terminator is |
| * not counted in the return value. |
| */ |
| if (buf_size > 0) |
| r->text_buf[len] = 0; |
| |
| return len; |
| } |
| |
| static size_t get_record_print_text_size(struct printk_info *info, |
| unsigned int line_count, |
| bool syslog, bool time) |
| { |
| char prefix[PRINTK_PREFIX_MAX]; |
| size_t prefix_len; |
| |
| prefix_len = info_print_prefix(info, syslog, time, prefix); |
| |
| /* |
| * Each line will be preceded with a prefix. The intermediate |
| * newlines are already within the text, but a final trailing |
| * newline will be added. |
| */ |
| return ((prefix_len * line_count) + info->text_len + 1); |
| } |
| |
| /* |
| * Beginning with @start_seq, find the first record where it and all following |
| * records up to (but not including) @max_seq fit into @size. |
| * |
| * @max_seq is simply an upper bound and does not need to exist. If the caller |
| * does not require an upper bound, -1 can be used for @max_seq. |
| */ |
| static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size, |
| bool syslog, bool time) |
| { |
| struct printk_info info; |
| unsigned int line_count; |
| size_t len = 0; |
| u64 seq; |
| |
| /* Determine the size of the records up to @max_seq. */ |
| prb_for_each_info(start_seq, prb, seq, &info, &line_count) { |
| if (info.seq >= max_seq) |
| break; |
| len += get_record_print_text_size(&info, line_count, syslog, time); |
| } |
| |
| /* |
| * Adjust the upper bound for the next loop to avoid subtracting |
| * lengths that were never added. |
| */ |
| if (seq < max_seq) |
| max_seq = seq; |
| |
| /* |
| * Move first record forward until length fits into the buffer. Ignore |
| * newest messages that were not counted in the above cycle. Messages |
| * might appear and get lost in the meantime. This is a best effort |
| * that prevents an infinite loop that could occur with a retry. |
| */ |
| prb_for_each_info(start_seq, prb, seq, &info, &line_count) { |
| if (len <= size || info.seq >= max_seq) |
| break; |
| len -= get_record_print_text_size(&info, line_count, syslog, time); |
| } |
| |
| return seq; |
| } |
| |
| /* The caller is responsible for making sure @size is greater than 0. */ |
| static int syslog_print(char __user *buf, int size) |
| { |
| struct printk_info info; |
| struct printk_record r; |
| char *text; |
| int len = 0; |
| u64 seq; |
| |
| text = kmalloc(PRINTK_MESSAGE_MAX, GFP_KERNEL); |
| if (!text) |
| return -ENOMEM; |
| |
| prb_rec_init_rd(&r, &info, text, PRINTK_MESSAGE_MAX); |
| |
| mutex_lock(&syslog_lock); |
| |
| /* |
| * Wait for the @syslog_seq record to be available. @syslog_seq may |
| * change while waiting. |
| */ |
| do { |
| seq = syslog_seq; |
| |
| mutex_unlock(&syslog_lock); |
| /* |
| * Guarantee this task is visible on the waitqueue before |
| * checking the wake condition. |
| * |
| * The full memory barrier within set_current_state() of |
| * prepare_to_wait_event() pairs with the full memory barrier |
| * within wq_has_sleeper(). |
| * |
| * This pairs with __wake_up_klogd:A. |
| */ |
| len = wait_event_interruptible(log_wait, |
| prb_read_valid(prb, seq, NULL)); /* LMM(syslog_print:A) */ |
| mutex_lock(&syslog_lock); |
| |
| if (len) |
| goto out; |
| } while (syslog_seq != seq); |
| |
| /* |
| * Copy records that fit into the buffer. The above cycle makes sure |
| * that the first record is always available. |
| */ |
| do { |
| size_t n; |
| size_t skip; |
| int err; |
| |
| if (!prb_read_valid(prb, syslog_seq, &r)) |
| break; |
| |
| if (r.info->seq != syslog_seq) { |
| /* message is gone, move to next valid one */ |
| syslog_seq = r.info->seq; |
| syslog_partial = 0; |
| } |
| |
| /* |
| * To keep reading/counting partial line consistent, |
| * use printk_time value as of the beginning of a line. |
| */ |
| if (!syslog_partial) |
| syslog_time = printk_time; |
| |
| skip = syslog_partial; |
| n = record_print_text(&r, true, syslog_time); |
| if (n - syslog_partial <= size) { |
| /* message fits into buffer, move forward */ |
| syslog_seq = r.info->seq + 1; |
| n -= syslog_partial; |
| syslog_partial = 0; |
| } else if (!len){ |
| /* partial read(), remember position */ |
| n = size; |
| syslog_partial += n; |
| } else |
| n = 0; |
| |
| if (!n) |
| break; |
| |
| mutex_unlock(&syslog_lock); |
| err = copy_to_user(buf, text + skip, n); |
| mutex_lock(&syslog_lock); |
| |
| if (err) { |
| if (!len) |
| len = -EFAULT; |
| break; |
| } |
| |
| len += n; |
| size -= n; |
| buf += n; |
| } while (size); |
| out: |
| mutex_unlock(&syslog_lock); |
| kfree(text); |
| return len; |
| } |
| |
| static int syslog_print_all(char __user *buf, int size, bool clear) |
| { |
| struct printk_info info; |
| struct printk_record r; |
| char *text; |
| int len = 0; |
| u64 seq; |
| bool time; |
| |
| text = kmalloc(PRINTK_MESSAGE_MAX, GFP_KERNEL); |
| if (!text) |
| return -ENOMEM; |
| |
| time = printk_time; |
| /* |
| * Find first record that fits, including all following records, |
| * into the user-provided buffer for this dump. |
| */ |
| seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1, |
| size, true, time); |
| |
| prb_rec_init_rd(&r, &info, text, PRINTK_MESSAGE_MAX); |
| |
| prb_for_each_record(seq, prb, seq, &r) { |
| int textlen; |
| |
| textlen = record_print_text(&r, true, time); |
| |
| if (len + textlen > size) { |
| seq--; |
| break; |
| } |
| |
| if (copy_to_user(buf + len, text, textlen)) |
| len = -EFAULT; |
| else |
| len += textlen; |
| |
| if (len < 0) |
| break; |
| } |
| |
| if (clear) { |
| mutex_lock(&syslog_lock); |
| latched_seq_write(&clear_seq, seq); |
| mutex_unlock(&syslog_lock); |
| } |
| |
| kfree(text); |
| return len; |
| } |
| |
| static void syslog_clear(void) |
| { |
| mutex_lock(&syslog_lock); |
| latched_seq_write(&clear_seq, prb_next_seq(prb)); |
| mutex_unlock(&syslog_lock); |
| } |
| |
| int do_syslog(int type, char __user *buf, int len, int source) |
| { |
| struct printk_info info; |
| 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 = syslog_print(buf, len); |
| break; |
| /* Read/clear last kernel messages */ |
| case SYSLOG_ACTION_READ_CLEAR: |
| clear = true; |
| fallthrough; |
| /* 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: |
| mutex_lock(&syslog_lock); |
| if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) { |
| /* No unread messages. */ |
| mutex_unlock(&syslog_lock); |
| return 0; |
| } |
| if (info.seq != syslog_seq) { |
| /* messages are gone, move to first one */ |
| syslog_seq = info.seq; |
| 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 = prb_next_seq(prb) - syslog_seq; |
| } else { |
| bool time = syslog_partial ? syslog_time : printk_time; |
| unsigned int line_count; |
| u64 seq; |
| |
| prb_for_each_info(syslog_seq, prb, seq, &info, |
| &line_count) { |
| error += get_record_print_text_size(&info, line_count, |
| true, time); |
| time = printk_time; |
| } |
| error -= syslog_partial; |
| } |
| mutex_unlock(&syslog_lock); |
| 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) |
| { |
| /* |
| * Do not use spinning in panic(). The panic CPU wants to keep the lock. |
| * Non-panic CPUs abandon the flush anyway. |
| * |
| * Just keep the lockdep annotation. The panic-CPU should avoid |
| * taking console_owner_lock because it might cause a deadlock. |
| * This looks like the easiest way how to prevent false lockdep |
| * reports without handling races a lockless way. |
| */ |
| if (panic_in_progress()) |
| goto lockdep; |
| |
| raw_spin_lock(&console_owner_lock); |
| console_owner = current; |
| raw_spin_unlock(&console_owner_lock); |
| |
| lockdep: |
| /* 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 |
| * @cookie: cookie returned from console_srcu_read_lock() |
| * |
| * 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 both the console_lock and the SRCU read lock if |
| * there was a busy waiter. They must not touch items synchronized by |
| * console_lock or SRCU read lock in this case. |
| * |
| * Return: 1 if the lock rights were passed, 0 otherwise. |
| */ |
| static int console_lock_spinning_disable_and_check(int cookie) |
| { |
| int waiter; |
| |
| /* |
| * Ignore spinning waiters during panic() because they might get stopped |
| * or blocked at any time, |
| * |
| * It is safe because nobody is allowed to start spinning during panic |
| * in the first place. If there has been a waiter then non panic CPUs |
| * might stay spinning. They would get stopped anyway. The panic context |
| * will never start spinning and an interrupted spin on panic CPU will |
| * never continue. |
| */ |
| if (panic_in_progress()) { |
| /* Keep lockdep happy. */ |
| spin_release(&console_owner_dep_map, _THIS_IP_); |
| return 0; |
| } |
| |
| 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_); |
| |
| /* |
| * Preserve lockdep lock ordering. Release the SRCU read lock before |
| * releasing the console_lock. |
| */ |
| console_srcu_read_unlock(cookie); |
| |
| /* |
| * 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; |
| |
| /* |
| * It's unsafe to spin once a panic has begun. If we are the |
| * panic CPU, we may have already halted the owner of the |
| * console_sem. If we are not the panic CPU, then we should |
| * avoid taking console_sem, so the panic CPU has a better |
| * chance of cleanly acquiring it later. |
| */ |
| if (panic_in_progress()) |
| return 0; |
| |
| 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_); |
| |
| /* |
| * Update @console_may_schedule for trylock because the previous |
| * owner may have been schedulable. |
| */ |
| console_may_schedule = 0; |
| |
| return 1; |
| } |
| |
| /* |
| * Recursion is tracked separately on each CPU. If NMIs are supported, an |
| * additional NMI context per CPU is also separately tracked. Until per-CPU |
| * is available, a separate "early tracking" is performed. |
| */ |
| static DEFINE_PER_CPU(u8, printk_count); |
| static u8 printk_count_early; |
| #ifdef CONFIG_HAVE_NMI |
| static DEFINE_PER_CPU(u8, printk_count_nmi); |
| static u8 printk_count_nmi_early; |
| #endif |
| |
| /* |
| * Recursion is limited to keep the output sane. printk() should not require |
| * more than 1 level of recursion (allowing, for example, printk() to trigger |
| * a WARN), but a higher value is used in case some printk-internal errors |
| * exist, such as the ringbuffer validation checks failing. |
| */ |
| #define PRINTK_MAX_RECURSION 3 |
| |
| /* |
| * Return a pointer to the dedicated counter for the CPU+context of the |
| * caller. |
| */ |
| static u8 *__printk_recursion_counter(void) |
| { |
| #ifdef CONFIG_HAVE_NMI |
| if (in_nmi()) { |
| if (printk_percpu_data_ready()) |
| return this_cpu_ptr(&printk_count_nmi); |
| return &printk_count_nmi_early; |
| } |
| #endif |
| if (printk_percpu_data_ready()) |
| return this_cpu_ptr(&printk_count); |
| return &printk_count_early; |
| } |
| |
| /* |
| * Enter recursion tracking. Interrupts are disabled to simplify tracking. |
| * The caller must check the boolean return value to see if the recursion is |
| * allowed. On failure, interrupts are not disabled. |
| * |
| * @recursion_ptr must be a variable of type (u8 *) and is the same variable |
| * that is passed to printk_exit_irqrestore(). |
| */ |
| #define printk_enter_irqsave(recursion_ptr, flags) \ |
| ({ \ |
| bool success = true; \ |
| \ |
| typecheck(u8 *, recursion_ptr); \ |
| local_irq_save(flags); \ |
| (recursion_ptr) = __printk_recursion_counter(); \ |
| if (*(recursion_ptr) > PRINTK_MAX_RECURSION) { \ |
| local_irq_restore(flags); \ |
| success = false; \ |
| } else { \ |
| (*(recursion_ptr))++; \ |
| } \ |
| success; \ |
| }) |
| |
| /* Exit recursion tracking, restoring interrupts. */ |
| #define printk_exit_irqrestore(recursion_ptr, flags) \ |
| do { \ |
| typecheck(u8 *, recursion_ptr); \ |
| (*(recursion_ptr))--; \ |
| local_irq_restore(flags); \ |
| } while (0) |
| |
| int printk_delay_msec __read_mostly; |
| |
| static inline void printk_delay(int level) |
| { |
| boot_delay_msec(level); |
| |
| if (unlikely(printk_delay_msec)) { |
| int m = printk_delay_msec; |
| |
| while (m--) { |
| mdelay(1); |
| touch_nmi_watchdog(); |
| } |
| } |
| } |
| |
| static inline u32 printk_caller_id(void) |
| { |
| return in_task() ? task_pid_nr(current) : |
| 0x80000000 + smp_processor_id(); |
| } |
| |
| /** |
| * printk_parse_prefix - Parse level and control flags. |
| * |
| * @text: The terminated text message. |
| * @level: A pointer to the current level value, will be updated. |
| * @flags: A pointer to the current printk_info flags, will be updated. |
| * |
| * @level may be NULL if the caller is not interested in the parsed value. |
| * Otherwise the variable pointed to by @level must be set to |
| * LOGLEVEL_DEFAULT in order to be updated with the parsed value. |
| * |
| * @flags may be NULL if the caller is not interested in the parsed value. |
| * Otherwise the variable pointed to by @flags will be OR'd with the parsed |
| * value. |
| * |
| * Return: The length of the parsed level and control flags. |
| */ |
| u16 printk_parse_prefix(const char *text, int *level, |
| enum printk_info_flags *flags) |
| { |
| u16 prefix_len = 0; |
| int kern_level; |
| |
| while (*text) { |
| kern_level = printk_get_level(text); |
| if (!kern_level) |
| break; |
| |
| switch (kern_level) { |
| case '0' ... '7': |
| if (level && *level == LOGLEVEL_DEFAULT) |
| *level = kern_level - '0'; |
| break; |
| case 'c': /* KERN_CONT */ |
| if (flags) |
| *flags |= LOG_CONT; |
| } |
| |
| prefix_len += 2; |
| text += 2; |
| } |
| |
| return prefix_len; |
| } |
| |
| __printf(5, 0) |
| static u16 printk_sprint(char *text, u16 size, int facility, |
| enum printk_info_flags *flags, const char *fmt, |
| va_list args) |
| { |
| u16 text_len; |
| |
| text_len = vscnprintf(text, size, fmt, args); |
| |
| /* Mark and strip a trailing newline. */ |
| if (text_len && text[text_len - 1] == '\n') { |
| text_len--; |
| *flags |= LOG_NEWLINE; |
| } |
| |
| /* Strip log level and control flags. */ |
| if (facility == 0) { |
| u16 prefix_len; |
| |
| prefix_len = printk_parse_prefix(text, NULL, NULL); |
| if (prefix_len) { |
| text_len -= prefix_len; |
| memmove(text, text + prefix_len, text_len); |
| } |
| } |
| |
| trace_console(text, text_len); |
| |
| return text_len; |
| } |
| |
| __printf(4, 0) |
| int vprintk_store(int facility, int level, |
| const struct dev_printk_info *dev_info, |
| const char *fmt, va_list args) |
| { |
| struct prb_reserved_entry e; |
| enum printk_info_flags flags = 0; |
| struct printk_record r; |
| unsigned long irqflags; |
| u16 trunc_msg_len = 0; |
| char prefix_buf[8]; |
| u8 *recursion_ptr; |
| u16 reserve_size; |
| va_list args2; |
| u32 caller_id; |
| u16 text_len; |
| int ret = 0; |
| u64 ts_nsec; |
| |
| if (!printk_enter_irqsave(recursion_ptr, irqflags)) |
| return 0; |
| |
| /* |
| * Since the duration of printk() can vary depending on the message |
| * and state of the ringbuffer, grab the timestamp now so that it is |
| * close to the call of printk(). This provides a more deterministic |
| * timestamp with respect to the caller. |
| */ |
| ts_nsec = local_clock(); |
| |
| caller_id = printk_caller_id(); |
| |
| /* |
| * The sprintf needs to come first since the syslog prefix might be |
| * passed in as a parameter. An extra byte must be reserved so that |
| * later the vscnprintf() into the reserved buffer has room for the |
| * terminating '\0', which is not counted by vsnprintf(). |
| */ |
| va_copy(args2, args); |
| reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1; |
| va_end(args2); |
| |
| if (reserve_size > PRINTKRB_RECORD_MAX) |
| reserve_size = PRINTKRB_RECORD_MAX; |
| |
| /* Extract log level or control flags. */ |
| if (facility == 0) |
| printk_parse_prefix(&prefix_buf[0], &level, &flags); |
| |
| if (level == LOGLEVEL_DEFAULT) |
| level = default_message_loglevel; |
| |
| if (dev_info) |
| flags |= LOG_NEWLINE; |
| |
| if (flags & LOG_CONT) { |
| prb_rec_init_wr(&r, reserve_size); |
| if (prb_reserve_in_last(&e, prb, &r, caller_id, PRINTKRB_RECORD_MAX)) { |
| text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size, |
| facility, &flags, fmt, args); |
| r.info->text_len += text_len; |
| |
| if (flags & LOG_NEWLINE) { |
| r.info->flags |= LOG_NEWLINE; |
| prb_final_commit(&e); |
| } else { |
| prb_commit(&e); |
| } |
| |
| ret = text_len; |
| goto out; |
| } |
| } |
| |
| /* |
| * Explicitly initialize the record before every prb_reserve() call. |
| * prb_reserve_in_last() and prb_reserve() purposely invalidate the |
| * structure when they fail. |
| */ |
| prb_rec_init_wr(&r, reserve_size); |
| if (!prb_reserve(&e, prb, &r)) { |
| /* truncate the message if it is too long for empty buffer */ |
| truncate_msg(&reserve_size, &trunc_msg_len); |
| |
| prb_rec_init_wr(&r, reserve_size + trunc_msg_len); |
| if (!prb_reserve(&e, prb, &r)) |
| goto out; |
| } |
| |
| /* fill message */ |
| text_len = printk_sprint(&r.text_buf[0], reserve_size, facility, &flags, fmt, args); |
| if (trunc_msg_len) |
| memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); |
| r.info->text_len = text_len + trunc_msg_len; |
| r.info->facility = facility; |
| r.info->level = level & 7; |
| r.info->flags = flags & 0x1f; |
| r.info->ts_nsec = ts_nsec; |
| r.info->caller_id = caller_id; |
| if (dev_info) |
| memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info)); |
| |
| /* A message without a trailing newline can be continued. */ |
| if (!(flags & LOG_NEWLINE)) |
| prb_commit(&e); |
| else |
| prb_final_commit(&e); |
| |
| ret = text_len + trunc_msg_len; |
| out: |
| printk_exit_irqrestore(recursion_ptr, irqflags); |
| return ret; |
| } |
| |
| asmlinkage int vprintk_emit(int facility, int level, |
| const struct dev_printk_info *dev_info, |
| const char *fmt, va_list args) |
| { |
| int printed_len; |
| bool in_sched = false; |
| |
| /* Suppress unimportant messages after panic happens */ |
| if (unlikely(suppress_printk)) |
| return 0; |
| |
| /* |
| * The messages on the panic CPU are the most important. If |
| * non-panic CPUs are generating any messages, they will be |
| * silently dropped. |
| */ |
| if (other_cpu_in_panic() && !panic_triggering_all_cpu_backtrace) |
| return 0; |
| |
| if (level == LOGLEVEL_SCHED) { |
| level = LOGLEVEL_DEFAULT; |
| in_sched = true; |
| } |
| |
| printk_delay(level); |
| |
| printed_len = vprintk_store(facility, level, dev_info, fmt, args); |
| |
| /* If called from the scheduler, we can not call up(). */ |
| if (!in_sched) { |
| /* |
| * The caller may be holding system-critical or |
| * timing-sensitive locks. Disable preemption during |
| * printing of all remaining records to all consoles so that |
| * this context can return as soon as possible. Hopefully |
| * another printk() caller will take over the printing. |
| */ |
| preempt_disable(); |
| /* |
| * Try to acquire and then immediately release the console |
| * semaphore. The release will print out buffers. With the |
| * spinning variant, this context tries to take over the |
| * printing from another printing context. |
| */ |
| if (console_trylock_spinning()) |
| console_unlock(); |
| preempt_enable(); |
| } |
| |
| if (in_sched) |
| defer_console_output(); |
| else |
| wake_up_klogd(); |
| |
| return printed_len; |
| } |
| EXPORT_SYMBOL(vprintk_emit); |
| |
| int vprintk_default(const char *fmt, va_list args) |
| { |
| return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args); |
| } |
| EXPORT_SYMBOL_GPL(vprintk_default); |
| |
| asmlinkage __visible int _printk(const char *fmt, ...) |
| { |
| va_list args; |
| int r; |
| |
| va_start(args, fmt); |
| r = vprintk(fmt, args); |
| va_end(args); |
| |
| return r; |
| } |
| EXPORT_SYMBOL(_printk); |
| |
| static bool pr_flush(int timeout_ms, bool reset_on_progress); |
| static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress); |
| |
| #else /* CONFIG_PRINTK */ |
| |
| #define printk_time false |
| |
| #define prb_read_valid(rb, seq, r) false |
| #define prb_first_valid_seq(rb) 0 |
| #define prb_next_seq(rb) 0 |
| |
| static u64 syslog_seq; |
| |
| static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; } |
| static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; } |
| |
| #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 void set_user_specified(struct console_cmdline *c, bool user_specified) |
| { |
| if (!user_specified) |
| return; |
| |
| /* |
| * @c console was defined by the user on the command line. |
| * Do not clear when added twice also by SPCR or the device tree. |
| */ |
| c->user_specified = true; |
| /* At least one console defined by the user on the command line. */ |
| console_set_on_cmdline = 1; |
| } |
| |
| static int __add_preferred_console(const char *name, const short idx, |
| const char *devname, char *options, |
| char *brl_options, bool user_specified) |
| { |
| struct console_cmdline *c; |
| int i; |
| |
| if (!name && !devname) |
| return -EINVAL; |
| |
| /* |
| * We use a signed short index for struct console for device drivers to |
| * indicate a not yet assigned index or port. However, a negative index |
| * value is not valid when the console name and index are defined on |
| * the command line. |
| */ |
| if (name && idx < 0) |
| return -EINVAL; |
| |
| /* |
| * 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] || c->devname[0]); |
| i++, c++) { |
| if ((name && strcmp(c->name, name) == 0 && c->index == idx) || |
| (devname && strcmp(c->devname, devname) == 0)) { |
| if (!brl_options) |
| preferred_console = i; |
| set_user_specified(c, user_specified); |
| return 0; |
| } |
| } |
| if (i == MAX_CMDLINECONSOLES) |
| return -E2BIG; |
| if (!brl_options) |
| preferred_console = i; |
| if (name) |
| strscpy(c->name, name); |
| if (devname) |
| strscpy(c->devname, devname); |
| c->options = options; |
| set_user_specified(c, user_specified); |
| 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) |
| { |
| static_assert(sizeof(console_cmdline[0].devname) >= sizeof(console_cmdline[0].name) + 4); |
| char buf[sizeof(console_cmdline[0].devname)]; |
| char *brl_options = NULL; |
| char *ttyname = NULL; |
| char *devname = NULL; |
| char *options; |
| char *s; |
| int idx; |
| |
| /* |
| * console="" or console=null have been suggested as a way to |
| * disable console output. Use ttynull that has been created |
| * for exactly this purpose. |
| */ |
| if (str[0] == 0 || strcmp(str, "null") == 0) { |
| __add_preferred_console("ttynull", 0, NULL, NULL, NULL, true); |
| return 1; |
| } |
| |
| if (_braille_console_setup(&str, &brl_options)) |
| return 1; |
| |
| /* For a DEVNAME:0.0 style console the character device is unknown early */ |
| if (strchr(str, ':')) |
| devname = buf; |
| else |
| ttyname = buf; |
| |
| /* |
| * Decode str into name, index, options. |
| */ |
| if (ttyname && isdigit(str[0])) |
| scnprintf(buf, sizeof(buf), "ttyS%s", str); |
| else |
| strscpy(buf, str); |
| |
| options = strchr(str, ','); |
| if (options) |
| *(options++) = 0; |
| |
| #ifdef __sparc__ |
| if (!strcmp(str, "ttya")) |
| strscpy(buf, "ttyS0"); |
| if (!strcmp(str, "ttyb")) |
| strscpy(buf, "ttyS1"); |
| #endif |
| |
| for (s = buf; *s; s++) |
| if ((ttyname && isdigit(*s)) || *s == ',') |
| break; |
| |
| /* @idx will get defined when devname matches. */ |
| if (devname) |
| idx = -1; |
| else |
| idx = simple_strtoul(s, NULL, 10); |
| |
| *s = 0; |
| |
| __add_preferred_console(ttyname, idx, devname, options, brl_options, true); |
| 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(const char *name, const short idx, char *options) |
| { |
| return __add_preferred_console(name, idx, NULL, options, NULL, false); |
| } |
| |
| /** |
| * match_devname_and_update_preferred_console - Update a preferred console |
| * when matching devname is found. |
| * @devname: DEVNAME:0.0 style device name |
| * @name: Name of the corresponding console driver, e.g. "ttyS" |
| * @idx: Console index, e.g. port number. |
| * |
| * The function checks whether a device with the given @devname is |
| * preferred via the console=DEVNAME:0.0 command line option. |
| * It fills the missing console driver name and console index |
| * so that a later register_console() call could find (match) |
| * and enable this device. |
| * |
| * It might be used when a driver subsystem initializes particular |
| * devices with already known DEVNAME:0.0 style names. And it |
| * could predict which console driver name and index this device |
| * would later get associated with. |
| * |
| * Return: 0 on success, negative error code on failure. |
| */ |
| int match_devname_and_update_preferred_console(const char *devname, |
| const char *name, |
| const short idx) |
| { |
| struct console_cmdline *c = console_cmdline; |
| int i; |
| |
| if (!devname || !strlen(devname) || !name || !strlen(name) || idx < 0) |
| return -EINVAL; |
| |
| for (i = 0; i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]); |
| i++, c++) { |
| if (!strcmp(devname, c->devname)) { |
| pr_info("associate the preferred console \"%s\" with \"%s%d\"\n", |
| devname, name, idx); |
| strscpy(c->name, name); |
| c->index = idx; |
| return 0; |
| } |
| } |
| |
| return -ENOENT; |
| } |
| |
| 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"); |
| |
| static bool printk_console_no_auto_verbose; |
| |
| void console_verbose(void) |
| { |
| if (console_loglevel && !printk_console_no_auto_verbose) |
| console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; |
| } |
| EXPORT_SYMBOL_GPL(console_verbose); |
| |
| module_param_named(console_no_auto_verbose, printk_console_no_auto_verbose, bool, 0644); |
| MODULE_PARM_DESC(console_no_auto_verbose, "Disable console loglevel raise to highest on oops/panic/etc"); |
| |
| /** |
| * suspend_console - suspend the console subsystem |
| * |
| * This disables printk() while we go into suspend states |
| */ |
| void suspend_console(void) |
| { |
| struct console *con; |
| |
| if (!console_suspend_enabled) |
| return; |
| pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
| pr_flush(1000, true); |
| |
| console_list_lock(); |
| for_each_console(con) |
| console_srcu_write_flags(con, con->flags | CON_SUSPENDED); |
| console_list_unlock(); |
| |
| /* |
| * Ensure that all SRCU list walks have completed. All printing |
| * contexts must be able to see that they are suspended so that it |
| * is guaranteed that all printing has stopped when this function |
| * completes. |
| */ |
| synchronize_srcu(&console_srcu); |
| } |
| |
| void resume_console(void) |
| { |
| struct console *con; |
| |
| if (!console_suspend_enabled) |
| return; |
| |
| console_list_lock(); |
| for_each_console(con) |
| console_srcu_write_flags(con, con->flags & ~CON_SUSPENDED); |
| console_list_unlock(); |
| |
| /* |
| * Ensure that all SRCU list walks have completed. All printing |
| * contexts must be able to see they are no longer suspended so |
| * that they are guaranteed to wake up and resume printing. |
| */ |
| synchronize_srcu(&console_srcu); |
| |
| pr_flush(1000, true); |
| } |
| |
| /** |
| * 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 - block the console subsystem from printing |
| * |
| * Acquires a lock which guarantees that no consoles will |
| * be in or enter their write() callback. |
| * |
| * Can sleep, returns nothing. |
| */ |
| void console_lock(void) |
| { |
| might_sleep(); |
| |
| /* On panic, the console_lock must be left to the panic cpu. */ |
| while (other_cpu_in_panic()) |
| msleep(1000); |
| |
| down_console_sem(); |
| console_locked = 1; |
| console_may_schedule = 1; |
| } |
| EXPORT_SYMBOL(console_lock); |
| |
| /** |
| * console_trylock - try to block the console subsystem from printing |
| * |
| * Try to acquire a lock which guarantees that no consoles will |
| * be in or enter their write() callback. |
| * |
| * returns 1 on success, and 0 on failure to acquire the lock. |
| */ |
| int console_trylock(void) |
| { |
| /* On panic, the console_lock must be left to the panic cpu. */ |
| if (other_cpu_in_panic()) |
| return 0; |
| if (down_trylock_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 the given console is currently capable and allowed to print |
| * records. |
| * |
| * Requires the console_srcu_read_lock. |
| */ |
| static inline bool console_is_usable(struct console *con) |
| { |
| short flags = console_srcu_read_flags(con); |
| |
| if (!(flags & CON_ENABLED)) |
| return false; |
| |
| if ((flags & CON_SUSPENDED)) |
| return false; |
| |
| if (!con->write) |
| return false; |
| |
| /* |
| * 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. |
| */ |
| if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME)) |
| return false; |
| |
| return true; |
| } |
| |
| static void __console_unlock(void) |
| { |
| console_locked = 0; |
| up_console_sem(); |
| } |
| |
| #ifdef CONFIG_PRINTK |
| |
| /* |
| * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This |
| * is achieved by shifting the existing message over and inserting the dropped |
| * message. |
| * |
| * @pmsg is the printk message to prepend. |
| * |
| * @dropped is the dropped count to report in the dropped message. |
| * |
| * If the message text in @pmsg->pbufs->outbuf does not have enough space for |
| * the dropped message, the message text will be sufficiently truncated. |
| * |
| * If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated. |
| */ |
| void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped) |
| { |
| struct printk_buffers *pbufs = pmsg->pbufs; |
| const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf); |
| const size_t outbuf_sz = sizeof(pbufs->outbuf); |
| char *scratchbuf = &pbufs->scratchbuf[0]; |
| char *outbuf = &pbufs->outbuf[0]; |
| size_t len; |
| |
| len = scnprintf(scratchbuf, scratchbuf_sz, |
| "** %lu printk messages dropped **\n", dropped); |
| |
| /* |
| * Make sure outbuf is sufficiently large before prepending. |
| * Keep at least the prefix when the message must be truncated. |
| * It is a rather theoretical problem when someone tries to |
| * use a minimalist buffer. |
| */ |
| if (WARN_ON_ONCE(len + PRINTK_PREFIX_MAX >= outbuf_sz)) |
| return; |
| |
| if (pmsg->outbuf_len + len >= outbuf_sz) { |
| /* Truncate the message, but keep it terminated. */ |
| pmsg->outbuf_len = outbuf_sz - (len + 1); |
| outbuf[pmsg->outbuf_len] = 0; |
| } |
| |
| memmove(outbuf + len, outbuf, pmsg->outbuf_len + 1); |
| memcpy(outbuf, scratchbuf, len); |
| pmsg->outbuf_len += len; |
| } |
| |
| /* |
| * Read and format the specified record (or a later record if the specified |
| * record is not available). |
| * |
| * @pmsg will contain the formatted result. @pmsg->pbufs must point to a |
| * struct printk_buffers. |
| * |
| * @seq is the record to read and format. If it is not available, the next |
| * valid record is read. |
| * |
| * @is_extended specifies if the message should be formatted for extended |
| * console output. |
| * |
| * @may_supress specifies if records may be skipped based on loglevel. |
| * |
| * Returns false if no record is available. Otherwise true and all fields |
| * of @pmsg are valid. (See the documentation of struct printk_message |
| * for information about the @pmsg fields.) |
| */ |
| bool printk_get_next_message(struct printk_message *pmsg, u64 seq, |
| bool is_extended, bool may_suppress) |
| { |
| struct printk_buffers *pbufs = pmsg->pbufs; |
| const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf); |
| const size_t outbuf_sz = sizeof(pbufs->outbuf); |
| char *scratchbuf = &pbufs->scratchbuf[0]; |
| char *outbuf = &pbufs->outbuf[0]; |
| struct printk_info info; |
| struct printk_record r; |
| size_t len = 0; |
| |
| /* |
| * Formatting extended messages requires a separate buffer, so use the |
| * scratch buffer to read in the ringbuffer text. |
| * |
| * Formatting normal messages is done in-place, so read the ringbuffer |
| * text directly into the output buffer. |
| */ |
| if (is_extended) |
| prb_rec_init_rd(&r, &info, scratchbuf, scratchbuf_sz); |
| else |
| prb_rec_init_rd(&r, &info, outbuf, outbuf_sz); |
| |
| if (!prb_read_valid(prb, seq, &r)) |
| return false; |
| |
| pmsg->seq = r.info->seq; |
| pmsg->dropped = r.info->seq - seq; |
| |
| /* Skip record that has level above the console loglevel. */ |
| if (may_suppress && suppress_message_printing(r.info->level)) |
| goto out; |
| |
| if (is_extended) { |
| len = info_print_ext_header(outbuf, outbuf_sz, r.info); |
| len += msg_print_ext_body(outbuf + len, outbuf_sz - len, |
| &r.text_buf[0], r.info->text_len, &r.info->dev_info); |
| } else { |
| len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time); |
| } |
| out: |
| pmsg->outbuf_len = len; |
| return true; |
| } |
| |
| /* |
| * Used as the printk buffers for non-panic, serialized console printing. |
| * This is for legacy (!CON_NBCON) as well as all boot (CON_BOOT) consoles. |
| * Its usage requires the console_lock held. |
| */ |
| struct printk_buffers printk_shared_pbufs; |
| |
| /* |
| * Print one record for the given console. The record printed is whatever |
| * record is the next available record for the given console. |
| * |
| * @handover will be set to true if a printk waiter has taken over the |
| * console_lock, in which case the caller is no longer holding both the |
| * console_lock and the SRCU read lock. Otherwise it is set to false. |
| * |
| * @cookie is the cookie from the SRCU read lock. |
| * |
| * Returns false if the given console has no next record to print, otherwise |
| * true. |
| * |
| * Requires the console_lock and the SRCU read lock. |
| */ |
| static bool console_emit_next_record(struct console *con, bool *handover, int cookie) |
| { |
| bool is_extended = console_srcu_read_flags(con) & CON_EXTENDED; |
| char *outbuf = &printk_shared_pbufs.outbuf[0]; |
| struct printk_message pmsg = { |
| .pbufs = &printk_shared_pbufs, |
| }; |
| unsigned long flags; |
| |
| *handover = false; |
| |
| if (!printk_get_next_message(&pmsg, con->seq, is_extended, true)) |
| return false; |
| |
| con->dropped += pmsg.dropped; |
| |
| /* Skip messages of formatted length 0. */ |
| if (pmsg.outbuf_len == 0) { |
| con->seq = pmsg.seq + 1; |
| goto skip; |
| } |
| |
| if (con->dropped && !is_extended) { |
| console_prepend_dropped(&pmsg, con->dropped); |
| con->dropped = 0; |
| } |
| |
| /* |
| * 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. |
| * |
| * Interrupts are disabled because the hand over to a waiter |
| * must not be interrupted until the hand over is completed |
| * (@console_waiter is cleared). |
| */ |
| printk_safe_enter_irqsave(flags); |
| console_lock_spinning_enable(); |
| |
| /* Do not trace print latency. */ |
| stop_critical_timings(); |
| |
| /* Write everything out to the hardware. */ |
| con->write(con, outbuf, pmsg.outbuf_len); |
| |
| start_critical_timings(); |
| |
| con->seq = pmsg.seq + 1; |
| |
| *handover = console_lock_spinning_disable_and_check(cookie); |
| printk_safe_exit_irqrestore(flags); |
| skip: |
| return true; |
| } |
| |
| #else |
| |
| static bool console_emit_next_record(struct console *con, bool *handover, int cookie) |
| { |
| *handover = false; |
| return false; |
| } |
| |
| #endif /* CONFIG_PRINTK */ |
| |
| /* |
| * Print out all remaining records to all consoles. |
| * |
| * @do_cond_resched is set by the caller. It can be true only in schedulable |
| * context. |
| * |
| * @next_seq is set to the sequence number after the last available record. |
| * The value is valid only when this function returns true. It means that all |
| * usable consoles are completely flushed. |
| * |
| * @handover will be set to true if a printk waiter has taken over the |
| * console_lock, in which case the caller is no longer holding the |
| * console_lock. Otherwise it is set to false. |
| * |
| * Returns true when there was at least one usable console and all messages |
| * were flushed to all usable consoles. A returned false informs the caller |
| * that everything was not flushed (either there were no usable consoles or |
| * another context has taken over printing or it is a panic situation and this |
| * is not the panic CPU). Regardless the reason, the caller should assume it |
| * is not useful to immediately try again. |
| * |
| * Requires the console_lock. |
| */ |
| static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover) |
| { |
| bool any_usable = false; |
| struct console *con; |
| bool any_progress; |
| int cookie; |
| |
| *next_seq = 0; |
| *handover = false; |
| |
| do { |
| any_progress = false; |
| |
| cookie = console_srcu_read_lock(); |
| for_each_console_srcu(con) { |
| bool progress; |
| |
| if (!console_is_usable(con)) |
| continue; |
| any_usable = true; |
| |
| progress = console_emit_next_record(con, handover, cookie); |
| |
| /* |
| * If a handover has occurred, the SRCU read lock |
| * is already released. |
| */ |
| if (*handover) |
| return false; |
| |
| /* Track the next of the highest seq flushed. */ |
| if (con->seq > *next_seq) |
| *next_seq = con->seq; |
| |
| if (!progress) |
| continue; |
| any_progress = true; |
| |
| /* Allow panic_cpu to take over the consoles safely. */ |
| if (other_cpu_in_panic()) |
| goto abandon; |
| |
| if (do_cond_resched) |
| cond_resched(); |
| } |
| console_srcu_read_unlock(cookie); |
| } while (any_progress); |
| |
| return any_usable; |
| |
| abandon: |
| console_srcu_read_unlock(cookie); |
| return false; |
| } |
| |
| /** |
| * console_unlock - unblock the console subsystem from printing |
| * |
| * Releases the console_lock which the caller holds to block printing of |
| * the console subsystem. |
| * |
| * 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. |
| * |
| * console_unlock(); may be called from any context. |
| */ |
| void console_unlock(void) |
| { |
| bool do_cond_resched; |
| bool handover; |
| bool flushed; |
| u64 next_seq; |
| |
| /* |
| * 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. Therefore, create |
| * a local to use for the printing loop. |
| */ |
| do_cond_resched = console_may_schedule; |
| |
| do { |
| console_may_schedule = 0; |
| |
| flushed = console_flush_all(do_cond_resched, &next_seq, &handover); |
| if (!handover) |
| __console_unlock(); |
| |
| /* |
| * Abort if there was a failure to flush all messages to all |
| * usable consoles. Either it is not possible to flush (in |
| * which case it would be an infinite loop of retrying) or |
| * another context has taken over printing. |
| */ |
| if (!flushed) |
| break; |
| |
| /* |
| * Some context may have added new records after |
| * console_flush_all() but before unlocking the console. |
| * Re-check if there is a new record to flush. If the trylock |
| * fails, another context is already handling the printing. |
| */ |
| } while (prb_read_valid(prb, next_seq, NULL) && console_trylock()); |
| } |
| 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) |
| { |
| bool found_unblank = false; |
| struct console *c; |
| int cookie; |
| |
| /* |
| * First check if there are any consoles implementing the unblank() |
| * callback. If not, there is no reason to continue and take the |
| * console lock, which in particular can be dangerous if |
| * @oops_in_progress is set. |
| */ |
| cookie = console_srcu_read_lock(); |
| for_each_console_srcu(c) { |
| if ((console_srcu_read_flags(c) & CON_ENABLED) && c->unblank) { |
| found_unblank = true; |
| break; |
| } |
| } |
| console_srcu_read_unlock(cookie); |
| if (!found_unblank) |
| return; |
| |
| /* |
| * Stop console printing because the unblank() callback may |
| * assume the console is not within its write() callback. |
| * |
| * If @oops_in_progress is set, this may be an atomic context. |
| * In that case, attempt a trylock as best-effort. |
| */ |
| if (oops_in_progress) { |
| /* Semaphores are not NMI-safe. */ |
| if (in_nmi()) |
| return; |
| |
| /* |
| * Attempting to trylock the console lock can deadlock |
| * if another CPU was stopped while modifying the |
| * semaphore. "Hope and pray" that this is not the |
| * current situation. |
| */ |
| if (down_trylock_console_sem() != 0) |
| return; |
| } else |
| console_lock(); |
| |
| console_locked = 1; |
| console_may_schedule = 0; |
| |
| cookie = console_srcu_read_lock(); |
| for_each_console_srcu(c) { |
| if ((console_srcu_read_flags(c) & CON_ENABLED) && c->unblank) |
| c->unblank(); |
| } |
| console_srcu_read_unlock(cookie); |
| |
| console_unlock(); |
| |
| if (!oops_in_progress) |
| pr_flush(1000, true); |
| } |
| |
| /* |
| * Rewind all consoles to the oldest available record. |
| * |
| * IMPORTANT: The function is safe only when called under |
| * console_lock(). It is not enforced because |
| * it is used as a best effort in panic(). |
| */ |
| static void __console_rewind_all(void) |
| { |
| struct console *c; |
| short flags; |
| int cookie; |
| u64 seq; |
| |
| seq = prb_first_valid_seq(prb); |
| |
| cookie = console_srcu_read_lock(); |
| for_each_console_srcu(c) { |
| flags = console_srcu_read_flags(c); |
| |
| if (flags & CON_NBCON) { |
| nbcon_seq_force(c, seq); |
| } else { |
| /* |
| * This assignment is safe only when called under |
| * console_lock(). On panic, legacy consoles are |
| * only best effort. |
| */ |
| c->seq = seq; |
| } |
| } |
| console_srcu_read_unlock(cookie); |
| } |
| |
| /** |
| * 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) |
| { |
| bool handover; |
| u64 next_seq; |
| |
| /* |
| * Ignore the console lock and flush out the messages. Attempting a |
| * trylock would not be useful because: |
| * |
| * - if it is contended, it must be ignored anyway |
| * - console_lock() and console_trylock() block and fail |
| * respectively in panic for non-panic CPUs |
| * - semaphores are not NMI-safe |
| */ |
| |
| /* |
| * If another context is holding the console lock, |
| * @console_may_schedule might be set. Clear it so that |
| * this context does not call cond_resched() while flushing. |
| */ |
| console_may_schedule = 0; |
| |
| if (mode == CONSOLE_REPLAY_ALL) |
| __console_rewind_all(); |
| |
| console_flush_all(false, &next_seq, &handover); |
| } |
| |
| /* |
| * 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; |
| int cookie; |
| |
| /* |
| * Take console_lock to serialize device() callback with |
| * other console operations. For example, fg_console is |
| * modified under console_lock when switching vt. |
| */ |
| console_lock(); |
| |
| cookie = console_srcu_read_lock(); |
| for_each_console_srcu(c) { |
| if (!c->device) |
| continue; |
| driver = c->device(c, index); |
| if (driver) |
| break; |
| } |
| console_srcu_read_unlock(cookie); |
| |
| 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) |
| { |
| __pr_flush(console, 1000, true); |
| console_list_lock(); |
| console_srcu_write_flags(console, console->flags & ~CON_ENABLED); |
| console_list_unlock(); |
| |
| /* |
| * Ensure that all SRCU list walks have completed. All contexts must |
| * be able to see that this console is disabled so that (for example) |
| * the caller can suspend the port without risk of another context |
| * using the port. |
| */ |
| synchronize_srcu(&console_srcu); |
| } |
| EXPORT_SYMBOL(console_stop); |
| |
| void console_start(struct console *console) |
| { |
| console_list_lock(); |
| console_srcu_write_flags(console, console->flags | CON_ENABLED); |
| console_list_unlock(); |
| __pr_flush(console, 1000, true); |
| } |
| 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); |
| |
| static int console_call_setup(struct console *newcon, char *options) |
| { |
| int err; |
| |
| if (!newcon->setup) |
| return 0; |
| |
| /* Synchronize with possible boot console. */ |
| console_lock(); |
| err = newcon->setup(newcon, options); |
| console_unlock(); |
| |
| return err; |
| } |
| |
| /* |
| * This is called by register_console() to try to match |
| * the newly registered console with any of the ones selected |
| * by either the command line or add_preferred_console() and |
| * setup/enable it. |
| * |
| * Care need to be taken with consoles that are statically |
| * enabled such as netconsole |
| */ |
| static int try_enable_preferred_console(struct console *newcon, |
| bool user_specified) |
| { |
| struct console_cmdline *c; |
| int i, err; |
| |
| for (i = 0, c = console_cmdline; |
| i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]); |
| i++, c++) {
|