3317 строки
84 KiB
C
3317 строки
84 KiB
C
/*
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* linux/kernel/printk.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* Modified to make sys_syslog() more flexible: added commands to
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* return the last 4k of kernel messages, regardless of whether
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* they've been read or not. Added option to suppress kernel printk's
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* to the console. Added hook for sending the console messages
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* elsewhere, in preparation for a serial line console (someday).
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* Ted Ts'o, 2/11/93.
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* Modified for sysctl support, 1/8/97, Chris Horn.
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* Fixed SMP synchronization, 08/08/99, Manfred Spraul
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* manfred@colorfullife.com
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* Rewrote bits to get rid of console_lock
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* 01Mar01 Andrew Morton
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/tty.h>
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#include <linux/tty_driver.h>
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#include <linux/console.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/nmi.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <linux/memblock.h>
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#include <linux/syscalls.h>
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#include <linux/crash_core.h>
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#include <linux/kdb.h>
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#include <linux/ratelimit.h>
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#include <linux/kmsg_dump.h>
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#include <linux/syslog.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/rculist.h>
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#include <linux/poll.h>
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#include <linux/irq_work.h>
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#include <linux/utsname.h>
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#include <linux/ctype.h>
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#include <linux/uio.h>
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#include <linux/sched/clock.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task_stack.h>
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#include <linux/uaccess.h>
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#include <asm/sections.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/printk.h>
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#include "console_cmdline.h"
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#include "braille.h"
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#include "internal.h"
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int console_printk[4] = {
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CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */
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MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */
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CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */
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CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */
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};
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/*
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* Low level drivers may need that to know if they can schedule in
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* their unblank() callback or not. So let's export it.
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*/
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int oops_in_progress;
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EXPORT_SYMBOL(oops_in_progress);
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/*
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* console_sem protects the console_drivers list, and also
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* provides serialisation for access to the entire console
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* driver system.
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*/
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static DEFINE_SEMAPHORE(console_sem);
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struct console *console_drivers;
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EXPORT_SYMBOL_GPL(console_drivers);
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#ifdef CONFIG_LOCKDEP
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static struct lockdep_map console_lock_dep_map = {
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.name = "console_lock"
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};
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#endif
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enum devkmsg_log_bits {
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__DEVKMSG_LOG_BIT_ON = 0,
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__DEVKMSG_LOG_BIT_OFF,
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__DEVKMSG_LOG_BIT_LOCK,
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};
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enum devkmsg_log_masks {
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DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON),
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DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF),
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DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK),
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};
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/* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */
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#define DEVKMSG_LOG_MASK_DEFAULT 0
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static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
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static int __control_devkmsg(char *str)
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{
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if (!str)
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return -EINVAL;
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if (!strncmp(str, "on", 2)) {
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devkmsg_log = DEVKMSG_LOG_MASK_ON;
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return 2;
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} else if (!strncmp(str, "off", 3)) {
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devkmsg_log = DEVKMSG_LOG_MASK_OFF;
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return 3;
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} else if (!strncmp(str, "ratelimit", 9)) {
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devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
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return 9;
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}
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return -EINVAL;
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}
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static int __init control_devkmsg(char *str)
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{
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if (__control_devkmsg(str) < 0)
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return 1;
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/*
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* Set sysctl string accordingly:
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*/
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if (devkmsg_log == DEVKMSG_LOG_MASK_ON)
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strcpy(devkmsg_log_str, "on");
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else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF)
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strcpy(devkmsg_log_str, "off");
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/* else "ratelimit" which is set by default. */
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/*
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* Sysctl cannot change it anymore. The kernel command line setting of
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* this parameter is to force the setting to be permanent throughout the
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* runtime of the system. This is a precation measure against userspace
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* trying to be a smarta** and attempting to change it up on us.
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*/
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devkmsg_log |= DEVKMSG_LOG_MASK_LOCK;
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return 0;
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}
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__setup("printk.devkmsg=", control_devkmsg);
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char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit";
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int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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char old_str[DEVKMSG_STR_MAX_SIZE];
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unsigned int old;
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int err;
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if (write) {
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if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK)
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return -EINVAL;
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old = devkmsg_log;
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strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE);
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}
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err = proc_dostring(table, write, buffer, lenp, ppos);
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if (err)
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return err;
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if (write) {
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err = __control_devkmsg(devkmsg_log_str);
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/*
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* Do not accept an unknown string OR a known string with
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* trailing crap...
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*/
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if (err < 0 || (err + 1 != *lenp)) {
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/* ... and restore old setting. */
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devkmsg_log = old;
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strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE);
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return -EINVAL;
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}
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}
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return 0;
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}
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/*
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* Number of registered extended console drivers.
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*
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* If extended consoles are present, in-kernel cont reassembly is disabled
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* and each fragment is stored as a separate log entry with proper
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* continuation flag so that every emitted message has full metadata. This
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* doesn't change the result for regular consoles or /proc/kmsg. For
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* /dev/kmsg, as long as the reader concatenates messages according to
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* consecutive continuation flags, the end result should be the same too.
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*/
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static int nr_ext_console_drivers;
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/*
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* Helper macros to handle lockdep when locking/unlocking console_sem. We use
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* macros instead of functions so that _RET_IP_ contains useful information.
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*/
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#define down_console_sem() do { \
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down(&console_sem);\
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mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
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} while (0)
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static int __down_trylock_console_sem(unsigned long ip)
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{
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int lock_failed;
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unsigned long flags;
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/*
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* Here and in __up_console_sem() we need to be in safe mode,
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* because spindump/WARN/etc from under console ->lock will
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* deadlock in printk()->down_trylock_console_sem() otherwise.
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*/
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printk_safe_enter_irqsave(flags);
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lock_failed = down_trylock(&console_sem);
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printk_safe_exit_irqrestore(flags);
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if (lock_failed)
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return 1;
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mutex_acquire(&console_lock_dep_map, 0, 1, ip);
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return 0;
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}
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#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
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static void __up_console_sem(unsigned long ip)
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{
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unsigned long flags;
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mutex_release(&console_lock_dep_map, 1, ip);
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printk_safe_enter_irqsave(flags);
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up(&console_sem);
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printk_safe_exit_irqrestore(flags);
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}
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#define up_console_sem() __up_console_sem(_RET_IP_)
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/*
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* This is used for debugging the mess that is the VT code by
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* keeping track if we have the console semaphore held. It's
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* definitely not the perfect debug tool (we don't know if _WE_
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* hold it and are racing, but it helps tracking those weird code
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* paths in the console code where we end up in places I want
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* locked without the console sempahore held).
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*/
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static int console_locked, console_suspended;
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/*
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* If exclusive_console is non-NULL then only this console is to be printed to.
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*/
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static struct console *exclusive_console;
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/*
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* Array of consoles built from command line options (console=)
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*/
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#define MAX_CMDLINECONSOLES 8
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static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
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static int preferred_console = -1;
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int console_set_on_cmdline;
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EXPORT_SYMBOL(console_set_on_cmdline);
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/* Flag: console code may call schedule() */
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static int console_may_schedule;
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enum con_msg_format_flags {
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MSG_FORMAT_DEFAULT = 0,
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MSG_FORMAT_SYSLOG = (1 << 0),
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};
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static int console_msg_format = MSG_FORMAT_DEFAULT;
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/*
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* The printk log buffer consists of a chain of concatenated variable
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* length records. Every record starts with a record header, containing
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* the overall length of the record.
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*
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* The heads to the first and last entry in the buffer, as well as the
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* sequence numbers of these entries are maintained when messages are
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* stored.
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*
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* If the heads indicate available messages, the length in the header
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* tells the start next message. A length == 0 for the next message
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* indicates a wrap-around to the beginning of the buffer.
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*
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* Every record carries the monotonic timestamp in microseconds, as well as
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* the standard userspace syslog level and syslog facility. The usual
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* kernel messages use LOG_KERN; userspace-injected messages always carry
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* a matching syslog facility, by default LOG_USER. The origin of every
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* message can be reliably determined that way.
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*
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* The human readable log message directly follows the message header. The
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* length of the message text is stored in the header, the stored message
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* is not terminated.
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*
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* Optionally, a message can carry a dictionary of properties (key/value pairs),
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* to provide userspace with a machine-readable message context.
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*
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* Examples for well-defined, commonly used property names are:
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* DEVICE=b12:8 device identifier
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* b12:8 block dev_t
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* c127:3 char dev_t
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* n8 netdev ifindex
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* +sound:card0 subsystem:devname
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* SUBSYSTEM=pci driver-core subsystem name
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*
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* Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
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* follows directly after a '=' character. Every property is terminated by
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* a '\0' character. The last property is not terminated.
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*
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* Example of a message structure:
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* 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
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* 0008 34 00 record is 52 bytes long
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* 000a 0b 00 text is 11 bytes long
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* 000c 1f 00 dictionary is 23 bytes long
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* 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
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* 0010 69 74 27 73 20 61 20 6c "it's a l"
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* 69 6e 65 "ine"
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* 001b 44 45 56 49 43 "DEVIC"
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* 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
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* 52 49 56 45 52 3d 62 75 "RIVER=bu"
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* 67 "g"
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* 0032 00 00 00 padding to next message header
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*
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* The 'struct printk_log' buffer header must never be directly exported to
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* userspace, it is a kernel-private implementation detail that might
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* need to be changed in the future, when the requirements change.
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*
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* /dev/kmsg exports the structured data in the following line format:
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* "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n"
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*
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* Users of the export format should ignore possible additional values
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* separated by ',', and find the message after the ';' character.
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*
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* The optional key/value pairs are attached as continuation lines starting
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* with a space character and terminated by a newline. All possible
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* non-prinatable characters are escaped in the "\xff" notation.
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*/
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enum log_flags {
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LOG_NOCONS = 1, /* already flushed, do not print to console */
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LOG_NEWLINE = 2, /* text ended with a newline */
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LOG_PREFIX = 4, /* text started with a prefix */
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LOG_CONT = 8, /* text is a fragment of a continuation line */
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};
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struct printk_log {
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u64 ts_nsec; /* timestamp in nanoseconds */
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u16 len; /* length of entire record */
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u16 text_len; /* length of text buffer */
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u16 dict_len; /* length of dictionary buffer */
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u8 facility; /* syslog facility */
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u8 flags:5; /* internal record flags */
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u8 level:3; /* syslog level */
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}
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#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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__packed __aligned(4)
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#endif
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;
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/*
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* The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
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* within the scheduler's rq lock. It must be released before calling
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* console_unlock() or anything else that might wake up a process.
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*/
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DEFINE_RAW_SPINLOCK(logbuf_lock);
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/*
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* Helper macros to lock/unlock logbuf_lock and switch between
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* printk-safe/unsafe modes.
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*/
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#define logbuf_lock_irq() \
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do { \
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printk_safe_enter_irq(); \
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raw_spin_lock(&logbuf_lock); \
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} while (0)
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#define logbuf_unlock_irq() \
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do { \
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raw_spin_unlock(&logbuf_lock); \
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printk_safe_exit_irq(); \
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} while (0)
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#define logbuf_lock_irqsave(flags) \
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do { \
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printk_safe_enter_irqsave(flags); \
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raw_spin_lock(&logbuf_lock); \
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} while (0)
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#define logbuf_unlock_irqrestore(flags) \
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do { \
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raw_spin_unlock(&logbuf_lock); \
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printk_safe_exit_irqrestore(flags); \
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} while (0)
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#ifdef CONFIG_PRINTK
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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/* the next printk record to read by syslog(READ) or /proc/kmsg */
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static u64 syslog_seq;
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static u32 syslog_idx;
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static size_t syslog_partial;
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/* index and sequence number of the first record stored in the buffer */
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static u64 log_first_seq;
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static u32 log_first_idx;
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/* index and sequence number of the next record to store in the buffer */
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static u64 log_next_seq;
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static u32 log_next_idx;
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/* the next printk record to write to the console */
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static u64 console_seq;
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static u32 console_idx;
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/* the next printk record to read after the last 'clear' command */
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static u64 clear_seq;
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static u32 clear_idx;
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#define PREFIX_MAX 32
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#define LOG_LINE_MAX (1024 - PREFIX_MAX)
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#define LOG_LEVEL(v) ((v) & 0x07)
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#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
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/* record buffer */
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#define LOG_ALIGN __alignof__(struct printk_log)
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#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
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static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
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static char *log_buf = __log_buf;
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static u32 log_buf_len = __LOG_BUF_LEN;
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/* Return log buffer address */
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char *log_buf_addr_get(void)
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{
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return log_buf;
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}
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/* Return log buffer size */
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u32 log_buf_len_get(void)
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{
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return log_buf_len;
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}
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/* human readable text of the record */
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static char *log_text(const struct printk_log *msg)
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{
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return (char *)msg + sizeof(struct printk_log);
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}
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/* optional key/value pair dictionary attached to the record */
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static char *log_dict(const struct printk_log *msg)
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{
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return (char *)msg + sizeof(struct printk_log) + msg->text_len;
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}
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/* get record by index; idx must point to valid msg */
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static struct printk_log *log_from_idx(u32 idx)
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{
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struct printk_log *msg = (struct printk_log *)(log_buf + idx);
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/*
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* A length == 0 record is the end of buffer marker. Wrap around and
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* read the message at the start of the buffer.
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*/
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if (!msg->len)
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return (struct printk_log *)log_buf;
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return msg;
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}
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/* get next record; idx must point to valid msg */
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static u32 log_next(u32 idx)
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{
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struct printk_log *msg = (struct printk_log *)(log_buf + idx);
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/* length == 0 indicates the end of the buffer; wrap */
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/*
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* A length == 0 record is the end of buffer marker. Wrap around and
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* read the message at the start of the buffer as *this* one, and
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* return the one after that.
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*/
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if (!msg->len) {
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msg = (struct printk_log *)log_buf;
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return msg->len;
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}
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return idx + msg->len;
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}
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/*
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* Check whether there is enough free space for the given message.
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*
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* The same values of first_idx and next_idx mean that the buffer
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* is either empty or full.
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*
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* If the buffer is empty, we must respect the position of the indexes.
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* They cannot be reset to the beginning of the buffer.
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*/
|
|
static int logbuf_has_space(u32 msg_size, bool empty)
|
|
{
|
|
u32 free;
|
|
|
|
if (log_next_idx > log_first_idx || empty)
|
|
free = max(log_buf_len - log_next_idx, log_first_idx);
|
|
else
|
|
free = log_first_idx - log_next_idx;
|
|
|
|
/*
|
|
* We need space also for an empty header that signalizes wrapping
|
|
* of the buffer.
|
|
*/
|
|
return free >= msg_size + sizeof(struct printk_log);
|
|
}
|
|
|
|
static int log_make_free_space(u32 msg_size)
|
|
{
|
|
while (log_first_seq < log_next_seq &&
|
|
!logbuf_has_space(msg_size, false)) {
|
|
/* drop old messages until we have enough contiguous space */
|
|
log_first_idx = log_next(log_first_idx);
|
|
log_first_seq++;
|
|
}
|
|
|
|
if (clear_seq < log_first_seq) {
|
|
clear_seq = log_first_seq;
|
|
clear_idx = log_first_idx;
|
|
}
|
|
|
|
/* sequence numbers are equal, so the log buffer is empty */
|
|
if (logbuf_has_space(msg_size, log_first_seq == log_next_seq))
|
|
return 0;
|
|
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* compute the message size including the padding bytes */
|
|
static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
|
|
{
|
|
u32 size;
|
|
|
|
size = sizeof(struct printk_log) + text_len + dict_len;
|
|
*pad_len = (-size) & (LOG_ALIGN - 1);
|
|
size += *pad_len;
|
|
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* Define how much of the log buffer we could take at maximum. The value
|
|
* must be greater than two. Note that only half of the buffer is available
|
|
* when the index points to the middle.
|
|
*/
|
|
#define MAX_LOG_TAKE_PART 4
|
|
static const char trunc_msg[] = "<truncated>";
|
|
|
|
static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
|
|
u16 *dict_len, u32 *pad_len)
|
|
{
|
|
/*
|
|
* The message should not take the whole buffer. Otherwise, it might
|
|
* get removed too soon.
|
|
*/
|
|
u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART;
|
|
if (*text_len > max_text_len)
|
|
*text_len = max_text_len;
|
|
/* enable the warning message */
|
|
*trunc_msg_len = strlen(trunc_msg);
|
|
/* disable the "dict" completely */
|
|
*dict_len = 0;
|
|
/* compute the size again, count also the warning message */
|
|
return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
|
|
}
|
|
|
|
/* insert record into the buffer, discard old ones, update heads */
|
|
static int log_store(int facility, int level,
|
|
enum log_flags flags, u64 ts_nsec,
|
|
const char *dict, u16 dict_len,
|
|
const char *text, u16 text_len)
|
|
{
|
|
struct printk_log *msg;
|
|
u32 size, pad_len;
|
|
u16 trunc_msg_len = 0;
|
|
|
|
/* number of '\0' padding bytes to next message */
|
|
size = msg_used_size(text_len, dict_len, &pad_len);
|
|
|
|
if (log_make_free_space(size)) {
|
|
/* truncate the message if it is too long for empty buffer */
|
|
size = truncate_msg(&text_len, &trunc_msg_len,
|
|
&dict_len, &pad_len);
|
|
/* survive when the log buffer is too small for trunc_msg */
|
|
if (log_make_free_space(size))
|
|
return 0;
|
|
}
|
|
|
|
if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
|
|
/*
|
|
* This message + an additional empty header does not fit
|
|
* at the end of the buffer. Add an empty header with len == 0
|
|
* to signify a wrap around.
|
|
*/
|
|
memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
|
|
log_next_idx = 0;
|
|
}
|
|
|
|
/* fill message */
|
|
msg = (struct printk_log *)(log_buf + log_next_idx);
|
|
memcpy(log_text(msg), text, text_len);
|
|
msg->text_len = text_len;
|
|
if (trunc_msg_len) {
|
|
memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
|
|
msg->text_len += trunc_msg_len;
|
|
}
|
|
memcpy(log_dict(msg), dict, dict_len);
|
|
msg->dict_len = dict_len;
|
|
msg->facility = facility;
|
|
msg->level = level & 7;
|
|
msg->flags = flags & 0x1f;
|
|
if (ts_nsec > 0)
|
|
msg->ts_nsec = ts_nsec;
|
|
else
|
|
msg->ts_nsec = local_clock();
|
|
memset(log_dict(msg) + dict_len, 0, pad_len);
|
|
msg->len = size;
|
|
|
|
/* insert message */
|
|
log_next_idx += msg->len;
|
|
log_next_seq++;
|
|
|
|
return msg->text_len;
|
|
}
|
|
|
|
int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
|
|
|
|
static int syslog_action_restricted(int type)
|
|
{
|
|
if (dmesg_restrict)
|
|
return 1;
|
|
/*
|
|
* Unless restricted, we allow "read all" and "get buffer size"
|
|
* for everybody.
|
|
*/
|
|
return type != SYSLOG_ACTION_READ_ALL &&
|
|
type != SYSLOG_ACTION_SIZE_BUFFER;
|
|
}
|
|
|
|
static int check_syslog_permissions(int type, int source)
|
|
{
|
|
/*
|
|
* If this is from /proc/kmsg and we've already opened it, then we've
|
|
* already done the capabilities checks at open time.
|
|
*/
|
|
if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN)
|
|
goto ok;
|
|
|
|
if (syslog_action_restricted(type)) {
|
|
if (capable(CAP_SYSLOG))
|
|
goto ok;
|
|
/*
|
|
* For historical reasons, accept CAP_SYS_ADMIN too, with
|
|
* a warning.
|
|
*/
|
|
if (capable(CAP_SYS_ADMIN)) {
|
|
pr_warn_once("%s (%d): Attempt to access syslog with "
|
|
"CAP_SYS_ADMIN but no CAP_SYSLOG "
|
|
"(deprecated).\n",
|
|
current->comm, task_pid_nr(current));
|
|
goto ok;
|
|
}
|
|
return -EPERM;
|
|
}
|
|
ok:
|
|
return security_syslog(type);
|
|
}
|
|
|
|
static void append_char(char **pp, char *e, char c)
|
|
{
|
|
if (*pp < e)
|
|
*(*pp)++ = c;
|
|
}
|
|
|
|
static ssize_t msg_print_ext_header(char *buf, size_t size,
|
|
struct printk_log *msg, u64 seq)
|
|
{
|
|
u64 ts_usec = msg->ts_nsec;
|
|
|
|
do_div(ts_usec, 1000);
|
|
|
|
return scnprintf(buf, size, "%u,%llu,%llu,%c;",
|
|
(msg->facility << 3) | msg->level, seq, ts_usec,
|
|
msg->flags & LOG_CONT ? 'c' : '-');
|
|
}
|
|
|
|
static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
char *dict, size_t dict_len,
|
|
char *text, size_t text_len)
|
|
{
|
|
char *p = buf, *e = buf + size;
|
|
size_t i;
|
|
|
|
/* escape non-printable characters */
|
|
for (i = 0; i < text_len; i++) {
|
|
unsigned char c = text[i];
|
|
|
|
if (c < ' ' || c >= 127 || c == '\\')
|
|
p += scnprintf(p, e - p, "\\x%02x", c);
|
|
else
|
|
append_char(&p, e, c);
|
|
}
|
|
append_char(&p, e, '\n');
|
|
|
|
if (dict_len) {
|
|
bool line = true;
|
|
|
|
for (i = 0; i < dict_len; i++) {
|
|
unsigned char c = dict[i];
|
|
|
|
if (line) {
|
|
append_char(&p, e, ' ');
|
|
line = false;
|
|
}
|
|
|
|
if (c == '\0') {
|
|
append_char(&p, e, '\n');
|
|
line = true;
|
|
continue;
|
|
}
|
|
|
|
if (c < ' ' || c >= 127 || c == '\\') {
|
|
p += scnprintf(p, e - p, "\\x%02x", c);
|
|
continue;
|
|
}
|
|
|
|
append_char(&p, e, c);
|
|
}
|
|
append_char(&p, e, '\n');
|
|
}
|
|
|
|
return p - buf;
|
|
}
|
|
|
|
/* /dev/kmsg - userspace message inject/listen interface */
|
|
struct devkmsg_user {
|
|
u64 seq;
|
|
u32 idx;
|
|
struct ratelimit_state rs;
|
|
struct mutex lock;
|
|
char buf[CONSOLE_EXT_LOG_MAX];
|
|
};
|
|
|
|
static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
|
|
{
|
|
char *buf, *line;
|
|
int level = default_message_loglevel;
|
|
int facility = 1; /* LOG_USER */
|
|
struct file *file = iocb->ki_filp;
|
|
struct devkmsg_user *user = file->private_data;
|
|
size_t len = iov_iter_count(from);
|
|
ssize_t ret = len;
|
|
|
|
if (!user || len > LOG_LINE_MAX)
|
|
return -EINVAL;
|
|
|
|
/* Ignore when user logging is disabled. */
|
|
if (devkmsg_log & DEVKMSG_LOG_MASK_OFF)
|
|
return len;
|
|
|
|
/* Ratelimit when not explicitly enabled. */
|
|
if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) {
|
|
if (!___ratelimit(&user->rs, current->comm))
|
|
return ret;
|
|
}
|
|
|
|
buf = kmalloc(len+1, GFP_KERNEL);
|
|
if (buf == NULL)
|
|
return -ENOMEM;
|
|
|
|
buf[len] = '\0';
|
|
if (!copy_from_iter_full(buf, len, from)) {
|
|
kfree(buf);
|
|
return -EFAULT;
|
|
}
|
|
|
|
/*
|
|
* Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
|
|
* the decimal value represents 32bit, the lower 3 bit are the log
|
|
* level, the rest are the log facility.
|
|
*
|
|
* If no prefix or no userspace facility is specified, we
|
|
* enforce LOG_USER, to be able to reliably distinguish
|
|
* kernel-generated messages from userspace-injected ones.
|
|
*/
|
|
line = buf;
|
|
if (line[0] == '<') {
|
|
char *endp = NULL;
|
|
unsigned int u;
|
|
|
|
u = simple_strtoul(line + 1, &endp, 10);
|
|
if (endp && endp[0] == '>') {
|
|
level = LOG_LEVEL(u);
|
|
if (LOG_FACILITY(u) != 0)
|
|
facility = LOG_FACILITY(u);
|
|
endp++;
|
|
len -= endp - line;
|
|
line = endp;
|
|
}
|
|
}
|
|
|
|
printk_emit(facility, level, NULL, 0, "%s", line);
|
|
kfree(buf);
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t devkmsg_read(struct file *file, char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
struct printk_log *msg;
|
|
size_t len;
|
|
ssize_t ret;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
|
|
ret = mutex_lock_interruptible(&user->lock);
|
|
if (ret)
|
|
return ret;
|
|
|
|
logbuf_lock_irq();
|
|
while (user->seq == log_next_seq) {
|
|
if (file->f_flags & O_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
logbuf_unlock_irq();
|
|
goto out;
|
|
}
|
|
|
|
logbuf_unlock_irq();
|
|
ret = wait_event_interruptible(log_wait,
|
|
user->seq != log_next_seq);
|
|
if (ret)
|
|
goto out;
|
|
logbuf_lock_irq();
|
|
}
|
|
|
|
if (user->seq < log_first_seq) {
|
|
/* our last seen message is gone, return error and reset */
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
ret = -EPIPE;
|
|
logbuf_unlock_irq();
|
|
goto out;
|
|
}
|
|
|
|
msg = log_from_idx(user->idx);
|
|
len = msg_print_ext_header(user->buf, sizeof(user->buf),
|
|
msg, user->seq);
|
|
len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
|
|
log_dict(msg), msg->dict_len,
|
|
log_text(msg), msg->text_len);
|
|
|
|
user->idx = log_next(user->idx);
|
|
user->seq++;
|
|
logbuf_unlock_irq();
|
|
|
|
if (len > count) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
if (copy_to_user(buf, user->buf, len)) {
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
ret = len;
|
|
out:
|
|
mutex_unlock(&user->lock);
|
|
return ret;
|
|
}
|
|
|
|
static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
loff_t ret = 0;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
if (offset)
|
|
return -ESPIPE;
|
|
|
|
logbuf_lock_irq();
|
|
switch (whence) {
|
|
case SEEK_SET:
|
|
/* the first record */
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
break;
|
|
case SEEK_DATA:
|
|
/*
|
|
* The first record after the last SYSLOG_ACTION_CLEAR,
|
|
* like issued by 'dmesg -c'. Reading /dev/kmsg itself
|
|
* changes no global state, and does not clear anything.
|
|
*/
|
|
user->idx = clear_idx;
|
|
user->seq = clear_seq;
|
|
break;
|
|
case SEEK_END:
|
|
/* after the last record */
|
|
user->idx = log_next_idx;
|
|
user->seq = log_next_seq;
|
|
break;
|
|
default:
|
|
ret = -EINVAL;
|
|
}
|
|
logbuf_unlock_irq();
|
|
return ret;
|
|
}
|
|
|
|
static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
__poll_t ret = 0;
|
|
|
|
if (!user)
|
|
return EPOLLERR|EPOLLNVAL;
|
|
|
|
poll_wait(file, &log_wait, wait);
|
|
|
|
logbuf_lock_irq();
|
|
if (user->seq < log_next_seq) {
|
|
/* return error when data has vanished underneath us */
|
|
if (user->seq < log_first_seq)
|
|
ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
|
|
else
|
|
ret = EPOLLIN|EPOLLRDNORM;
|
|
}
|
|
logbuf_unlock_irq();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int devkmsg_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct devkmsg_user *user;
|
|
int err;
|
|
|
|
if (devkmsg_log & DEVKMSG_LOG_MASK_OFF)
|
|
return -EPERM;
|
|
|
|
/* write-only does not need any file context */
|
|
if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
|
|
err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
|
|
SYSLOG_FROM_READER);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
|
|
if (!user)
|
|
return -ENOMEM;
|
|
|
|
ratelimit_default_init(&user->rs);
|
|
ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE);
|
|
|
|
mutex_init(&user->lock);
|
|
|
|
logbuf_lock_irq();
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
logbuf_unlock_irq();
|
|
|
|
file->private_data = user;
|
|
return 0;
|
|
}
|
|
|
|
static int devkmsg_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
|
|
if (!user)
|
|
return 0;
|
|
|
|
ratelimit_state_exit(&user->rs);
|
|
|
|
mutex_destroy(&user->lock);
|
|
kfree(user);
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations kmsg_fops = {
|
|
.open = devkmsg_open,
|
|
.read = devkmsg_read,
|
|
.write_iter = devkmsg_write,
|
|
.llseek = devkmsg_llseek,
|
|
.poll = devkmsg_poll,
|
|
.release = devkmsg_release,
|
|
};
|
|
|
|
#ifdef CONFIG_CRASH_CORE
|
|
/*
|
|
* This appends the listed symbols to /proc/vmcore
|
|
*
|
|
* /proc/vmcore is used by various utilities, like crash and makedumpfile to
|
|
* obtain access to symbols that are otherwise very difficult to locate. These
|
|
* symbols are specifically used so that utilities can access and extract the
|
|
* dmesg log from a vmcore file after a crash.
|
|
*/
|
|
void log_buf_vmcoreinfo_setup(void)
|
|
{
|
|
VMCOREINFO_SYMBOL(log_buf);
|
|
VMCOREINFO_SYMBOL(log_buf_len);
|
|
VMCOREINFO_SYMBOL(log_first_idx);
|
|
VMCOREINFO_SYMBOL(clear_idx);
|
|
VMCOREINFO_SYMBOL(log_next_idx);
|
|
/*
|
|
* Export struct printk_log size and field offsets. User space tools can
|
|
* parse it and detect any changes to structure down the line.
|
|
*/
|
|
VMCOREINFO_STRUCT_SIZE(printk_log);
|
|
VMCOREINFO_OFFSET(printk_log, ts_nsec);
|
|
VMCOREINFO_OFFSET(printk_log, len);
|
|
VMCOREINFO_OFFSET(printk_log, text_len);
|
|
VMCOREINFO_OFFSET(printk_log, dict_len);
|
|
}
|
|
#endif
|
|
|
|
/* requested log_buf_len from kernel cmdline */
|
|
static unsigned long __initdata new_log_buf_len;
|
|
|
|
/* we practice scaling the ring buffer by powers of 2 */
|
|
static void __init log_buf_len_update(unsigned size)
|
|
{
|
|
if (size)
|
|
size = roundup_pow_of_two(size);
|
|
if (size > log_buf_len)
|
|
new_log_buf_len = size;
|
|
}
|
|
|
|
/* save requested log_buf_len since it's too early to process it */
|
|
static int __init log_buf_len_setup(char *str)
|
|
{
|
|
unsigned size = memparse(str, &str);
|
|
|
|
log_buf_len_update(size);
|
|
|
|
return 0;
|
|
}
|
|
early_param("log_buf_len", log_buf_len_setup);
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
|
|
|
|
static void __init log_buf_add_cpu(void)
|
|
{
|
|
unsigned int cpu_extra;
|
|
|
|
/*
|
|
* archs should set up cpu_possible_bits properly with
|
|
* set_cpu_possible() after setup_arch() but just in
|
|
* case lets ensure this is valid.
|
|
*/
|
|
if (num_possible_cpus() == 1)
|
|
return;
|
|
|
|
cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
|
|
|
|
/* by default this will only continue through for large > 64 CPUs */
|
|
if (cpu_extra <= __LOG_BUF_LEN / 2)
|
|
return;
|
|
|
|
pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
|
|
__LOG_CPU_MAX_BUF_LEN);
|
|
pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
|
|
cpu_extra);
|
|
pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN);
|
|
|
|
log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
|
|
}
|
|
#else /* !CONFIG_SMP */
|
|
static inline void log_buf_add_cpu(void) {}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
void __init setup_log_buf(int early)
|
|
{
|
|
unsigned long flags;
|
|
char *new_log_buf;
|
|
int free;
|
|
|
|
if (log_buf != __log_buf)
|
|
return;
|
|
|
|
if (!early && !new_log_buf_len)
|
|
log_buf_add_cpu();
|
|
|
|
if (!new_log_buf_len)
|
|
return;
|
|
|
|
if (early) {
|
|
new_log_buf =
|
|
memblock_virt_alloc(new_log_buf_len, LOG_ALIGN);
|
|
} else {
|
|
new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len,
|
|
LOG_ALIGN);
|
|
}
|
|
|
|
if (unlikely(!new_log_buf)) {
|
|
pr_err("log_buf_len: %ld bytes not available\n",
|
|
new_log_buf_len);
|
|
return;
|
|
}
|
|
|
|
logbuf_lock_irqsave(flags);
|
|
log_buf_len = new_log_buf_len;
|
|
log_buf = new_log_buf;
|
|
new_log_buf_len = 0;
|
|
free = __LOG_BUF_LEN - log_next_idx;
|
|
memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
|
|
logbuf_unlock_irqrestore(flags);
|
|
|
|
pr_info("log_buf_len: %d bytes\n", log_buf_len);
|
|
pr_info("early log buf free: %d(%d%%)\n",
|
|
free, (free * 100) / __LOG_BUF_LEN);
|
|
}
|
|
|
|
static bool __read_mostly ignore_loglevel;
|
|
|
|
static int __init ignore_loglevel_setup(char *str)
|
|
{
|
|
ignore_loglevel = true;
|
|
pr_info("debug: ignoring loglevel setting.\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("ignore_loglevel", ignore_loglevel_setup);
|
|
module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(ignore_loglevel,
|
|
"ignore loglevel setting (prints all kernel messages to the console)");
|
|
|
|
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_time(u64 ts, char *buf)
|
|
{
|
|
unsigned long rem_nsec;
|
|
|
|
if (!printk_time)
|
|
return 0;
|
|
|
|
rem_nsec = do_div(ts, 1000000000);
|
|
|
|
if (!buf)
|
|
return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
|
|
|
|
return sprintf(buf, "[%5lu.%06lu] ",
|
|
(unsigned long)ts, rem_nsec / 1000);
|
|
}
|
|
|
|
static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
|
|
{
|
|
size_t len = 0;
|
|
unsigned int prefix = (msg->facility << 3) | msg->level;
|
|
|
|
if (syslog) {
|
|
if (buf) {
|
|
len += sprintf(buf, "<%u>", prefix);
|
|
} else {
|
|
len += 3;
|
|
if (prefix > 999)
|
|
len += 3;
|
|
else if (prefix > 99)
|
|
len += 2;
|
|
else if (prefix > 9)
|
|
len++;
|
|
}
|
|
}
|
|
|
|
len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
|
|
return len;
|
|
}
|
|
|
|
static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *buf, size_t size)
|
|
{
|
|
const char *text = log_text(msg);
|
|
size_t text_size = msg->text_len;
|
|
size_t len = 0;
|
|
|
|
do {
|
|
const char *next = memchr(text, '\n', text_size);
|
|
size_t text_len;
|
|
|
|
if (next) {
|
|
text_len = next - text;
|
|
next++;
|
|
text_size -= next - text;
|
|
} else {
|
|
text_len = text_size;
|
|
}
|
|
|
|
if (buf) {
|
|
if (print_prefix(msg, syslog, NULL) +
|
|
text_len + 1 >= size - len)
|
|
break;
|
|
|
|
len += print_prefix(msg, syslog, buf + len);
|
|
memcpy(buf + len, text, text_len);
|
|
len += text_len;
|
|
buf[len++] = '\n';
|
|
} else {
|
|
/* SYSLOG_ACTION_* buffer size only calculation */
|
|
len += print_prefix(msg, syslog, NULL);
|
|
len += text_len;
|
|
len++;
|
|
}
|
|
|
|
text = next;
|
|
} while (text);
|
|
|
|
return len;
|
|
}
|
|
|
|
static int syslog_print(char __user *buf, int size)
|
|
{
|
|
char *text;
|
|
struct printk_log *msg;
|
|
int len = 0;
|
|
|
|
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
while (size > 0) {
|
|
size_t n;
|
|
size_t skip;
|
|
|
|
logbuf_lock_irq();
|
|
if (syslog_seq < log_first_seq) {
|
|
/* messages are gone, move to first one */
|
|
syslog_seq = log_first_seq;
|
|
syslog_idx = log_first_idx;
|
|
syslog_partial = 0;
|
|
}
|
|
if (syslog_seq == log_next_seq) {
|
|
logbuf_unlock_irq();
|
|
break;
|
|
}
|
|
|
|
skip = syslog_partial;
|
|
msg = log_from_idx(syslog_idx);
|
|
n = msg_print_text(msg, true, text, LOG_LINE_MAX + PREFIX_MAX);
|
|
if (n - syslog_partial <= size) {
|
|
/* message fits into buffer, move forward */
|
|
syslog_idx = log_next(syslog_idx);
|
|
syslog_seq++;
|
|
n -= syslog_partial;
|
|
syslog_partial = 0;
|
|
} else if (!len){
|
|
/* partial read(), remember position */
|
|
n = size;
|
|
syslog_partial += n;
|
|
} else
|
|
n = 0;
|
|
logbuf_unlock_irq();
|
|
|
|
if (!n)
|
|
break;
|
|
|
|
if (copy_to_user(buf, text + skip, n)) {
|
|
if (!len)
|
|
len = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
len += n;
|
|
size -= n;
|
|
buf += n;
|
|
}
|
|
|
|
kfree(text);
|
|
return len;
|
|
}
|
|
|
|
static int syslog_print_all(char __user *buf, int size, bool clear)
|
|
{
|
|
char *text;
|
|
int len = 0;
|
|
|
|
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
logbuf_lock_irq();
|
|
if (buf) {
|
|
u64 next_seq;
|
|
u64 seq;
|
|
u32 idx;
|
|
|
|
/*
|
|
* Find first record that fits, including all following records,
|
|
* into the user-provided buffer for this dump.
|
|
*/
|
|
seq = clear_seq;
|
|
idx = clear_idx;
|
|
while (seq < log_next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
len += msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* move first record forward until length fits into the buffer */
|
|
seq = clear_seq;
|
|
idx = clear_idx;
|
|
while (len > size && seq < log_next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
len -= msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* last message fitting into this dump */
|
|
next_seq = log_next_seq;
|
|
|
|
len = 0;
|
|
while (len >= 0 && seq < next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
int textlen;
|
|
|
|
textlen = msg_print_text(msg, true, text,
|
|
LOG_LINE_MAX + PREFIX_MAX);
|
|
if (textlen < 0) {
|
|
len = textlen;
|
|
break;
|
|
}
|
|
idx = log_next(idx);
|
|
seq++;
|
|
|
|
logbuf_unlock_irq();
|
|
if (copy_to_user(buf + len, text, textlen))
|
|
len = -EFAULT;
|
|
else
|
|
len += textlen;
|
|
logbuf_lock_irq();
|
|
|
|
if (seq < log_first_seq) {
|
|
/* messages are gone, move to next one */
|
|
seq = log_first_seq;
|
|
idx = log_first_idx;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (clear) {
|
|
clear_seq = log_next_seq;
|
|
clear_idx = log_next_idx;
|
|
}
|
|
logbuf_unlock_irq();
|
|
|
|
kfree(text);
|
|
return len;
|
|
}
|
|
|
|
int do_syslog(int type, char __user *buf, int len, int source)
|
|
{
|
|
bool clear = false;
|
|
static int saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
int error;
|
|
|
|
error = check_syslog_permissions(type, source);
|
|
if (error)
|
|
return error;
|
|
|
|
switch (type) {
|
|
case SYSLOG_ACTION_CLOSE: /* Close log */
|
|
break;
|
|
case SYSLOG_ACTION_OPEN: /* Open log */
|
|
break;
|
|
case SYSLOG_ACTION_READ: /* Read from log */
|
|
if (!buf || len < 0)
|
|
return -EINVAL;
|
|
if (!len)
|
|
return 0;
|
|
if (!access_ok(VERIFY_WRITE, buf, len))
|
|
return -EFAULT;
|
|
error = wait_event_interruptible(log_wait,
|
|
syslog_seq != log_next_seq);
|
|
if (error)
|
|
return error;
|
|
error = syslog_print(buf, len);
|
|
break;
|
|
/* Read/clear last kernel messages */
|
|
case SYSLOG_ACTION_READ_CLEAR:
|
|
clear = true;
|
|
/* FALL THRU */
|
|
/* Read last kernel messages */
|
|
case SYSLOG_ACTION_READ_ALL:
|
|
if (!buf || len < 0)
|
|
return -EINVAL;
|
|
if (!len)
|
|
return 0;
|
|
if (!access_ok(VERIFY_WRITE, buf, len))
|
|
return -EFAULT;
|
|
error = syslog_print_all(buf, len, clear);
|
|
break;
|
|
/* Clear ring buffer */
|
|
case SYSLOG_ACTION_CLEAR:
|
|
syslog_print_all(NULL, 0, true);
|
|
break;
|
|
/* Disable logging to console */
|
|
case SYSLOG_ACTION_CONSOLE_OFF:
|
|
if (saved_console_loglevel == LOGLEVEL_DEFAULT)
|
|
saved_console_loglevel = console_loglevel;
|
|
console_loglevel = minimum_console_loglevel;
|
|
break;
|
|
/* Enable logging to console */
|
|
case SYSLOG_ACTION_CONSOLE_ON:
|
|
if (saved_console_loglevel != LOGLEVEL_DEFAULT) {
|
|
console_loglevel = saved_console_loglevel;
|
|
saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
}
|
|
break;
|
|
/* Set level of messages printed to console */
|
|
case SYSLOG_ACTION_CONSOLE_LEVEL:
|
|
if (len < 1 || len > 8)
|
|
return -EINVAL;
|
|
if (len < minimum_console_loglevel)
|
|
len = minimum_console_loglevel;
|
|
console_loglevel = len;
|
|
/* Implicitly re-enable logging to console */
|
|
saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
break;
|
|
/* Number of chars in the log buffer */
|
|
case SYSLOG_ACTION_SIZE_UNREAD:
|
|
logbuf_lock_irq();
|
|
if (syslog_seq < log_first_seq) {
|
|
/* messages are gone, move to first one */
|
|
syslog_seq = log_first_seq;
|
|
syslog_idx = log_first_idx;
|
|
syslog_partial = 0;
|
|
}
|
|
if (source == SYSLOG_FROM_PROC) {
|
|
/*
|
|
* Short-cut for poll(/"proc/kmsg") which simply checks
|
|
* for pending data, not the size; return the count of
|
|
* records, not the length.
|
|
*/
|
|
error = log_next_seq - syslog_seq;
|
|
} else {
|
|
u64 seq = syslog_seq;
|
|
u32 idx = syslog_idx;
|
|
|
|
while (seq < log_next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
error += msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
error -= syslog_partial;
|
|
}
|
|
logbuf_unlock_irq();
|
|
break;
|
|
/* Size of the log buffer */
|
|
case SYSLOG_ACTION_SIZE_BUFFER:
|
|
error = log_buf_len;
|
|
break;
|
|
default:
|
|
error = -EINVAL;
|
|
break;
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
|
|
{
|
|
return do_syslog(type, buf, len, SYSLOG_FROM_READER);
|
|
}
|
|
|
|
/*
|
|
* Special console_lock variants that help to reduce the risk of soft-lockups.
|
|
* They allow to pass console_lock to another printk() call using a busy wait.
|
|
*/
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
static struct lockdep_map console_owner_dep_map = {
|
|
.name = "console_owner"
|
|
};
|
|
#endif
|
|
|
|
static DEFINE_RAW_SPINLOCK(console_owner_lock);
|
|
static struct task_struct *console_owner;
|
|
static bool console_waiter;
|
|
|
|
/**
|
|
* console_lock_spinning_enable - mark beginning of code where another
|
|
* thread might safely busy wait
|
|
*
|
|
* This basically converts console_lock into a spinlock. This marks
|
|
* the section where the console_lock owner can not sleep, because
|
|
* there may be a waiter spinning (like a spinlock). Also it must be
|
|
* ready to hand over the lock at the end of the section.
|
|
*/
|
|
static void console_lock_spinning_enable(void)
|
|
{
|
|
raw_spin_lock(&console_owner_lock);
|
|
console_owner = current;
|
|
raw_spin_unlock(&console_owner_lock);
|
|
|
|
/* The waiter may spin on us after setting console_owner */
|
|
spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
|
|
}
|
|
|
|
/**
|
|
* console_lock_spinning_disable_and_check - mark end of code where another
|
|
* thread was able to busy wait and check if there is a waiter
|
|
*
|
|
* This is called at the end of the section where spinning is allowed.
|
|
* It has two functions. First, it is a signal that it is no longer
|
|
* safe to start busy waiting for the lock. Second, it checks if
|
|
* there is a busy waiter and passes the lock rights to her.
|
|
*
|
|
* Important: Callers lose the lock if there was a busy waiter.
|
|
* They must not touch items synchronized by console_lock
|
|
* in this case.
|
|
*
|
|
* Return: 1 if the lock rights were passed, 0 otherwise.
|
|
*/
|
|
static int console_lock_spinning_disable_and_check(void)
|
|
{
|
|
int waiter;
|
|
|
|
raw_spin_lock(&console_owner_lock);
|
|
waiter = READ_ONCE(console_waiter);
|
|
console_owner = NULL;
|
|
raw_spin_unlock(&console_owner_lock);
|
|
|
|
if (!waiter) {
|
|
spin_release(&console_owner_dep_map, 1, _THIS_IP_);
|
|
return 0;
|
|
}
|
|
|
|
/* The waiter is now free to continue */
|
|
WRITE_ONCE(console_waiter, false);
|
|
|
|
spin_release(&console_owner_dep_map, 1, _THIS_IP_);
|
|
|
|
/*
|
|
* Hand off console_lock to waiter. The waiter will perform
|
|
* the up(). After this, the waiter is the console_lock owner.
|
|
*/
|
|
mutex_release(&console_lock_dep_map, 1, _THIS_IP_);
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* console_trylock_spinning - try to get console_lock by busy waiting
|
|
*
|
|
* This allows to busy wait for the console_lock when the current
|
|
* owner is running in specially marked sections. It means that
|
|
* the current owner is running and cannot reschedule until it
|
|
* is ready to lose the lock.
|
|
*
|
|
* Return: 1 if we got the lock, 0 othrewise
|
|
*/
|
|
static int console_trylock_spinning(void)
|
|
{
|
|
struct task_struct *owner = NULL;
|
|
bool waiter;
|
|
bool spin = false;
|
|
unsigned long flags;
|
|
|
|
if (console_trylock())
|
|
return 1;
|
|
|
|
printk_safe_enter_irqsave(flags);
|
|
|
|
raw_spin_lock(&console_owner_lock);
|
|
owner = READ_ONCE(console_owner);
|
|
waiter = READ_ONCE(console_waiter);
|
|
if (!waiter && owner && owner != current) {
|
|
WRITE_ONCE(console_waiter, true);
|
|
spin = true;
|
|
}
|
|
raw_spin_unlock(&console_owner_lock);
|
|
|
|
/*
|
|
* If there is an active printk() writing to the
|
|
* consoles, instead of having it write our data too,
|
|
* see if we can offload that load from the active
|
|
* printer, and do some printing ourselves.
|
|
* Go into a spin only if there isn't already a waiter
|
|
* spinning, and there is an active printer, and
|
|
* that active printer isn't us (recursive printk?).
|
|
*/
|
|
if (!spin) {
|
|
printk_safe_exit_irqrestore(flags);
|
|
return 0;
|
|
}
|
|
|
|
/* We spin waiting for the owner to release us */
|
|
spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
|
|
/* Owner will clear console_waiter on hand off */
|
|
while (READ_ONCE(console_waiter))
|
|
cpu_relax();
|
|
spin_release(&console_owner_dep_map, 1, _THIS_IP_);
|
|
|
|
printk_safe_exit_irqrestore(flags);
|
|
/*
|
|
* The owner passed the console lock to us.
|
|
* Since we did not spin on console lock, annotate
|
|
* this as a trylock. Otherwise lockdep will
|
|
* complain.
|
|
*/
|
|
mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Call the console drivers, asking them to write out
|
|
* log_buf[start] to log_buf[end - 1].
|
|
* The console_lock must be held.
|
|
*/
|
|
static void call_console_drivers(const char *ext_text, size_t ext_len,
|
|
const char *text, size_t len)
|
|
{
|
|
struct console *con;
|
|
|
|
trace_console_rcuidle(text, len);
|
|
|
|
if (!console_drivers)
|
|
return;
|
|
|
|
for_each_console(con) {
|
|
if (exclusive_console && con != exclusive_console)
|
|
continue;
|
|
if (!(con->flags & CON_ENABLED))
|
|
continue;
|
|
if (!con->write)
|
|
continue;
|
|
if (!cpu_online(smp_processor_id()) &&
|
|
!(con->flags & CON_ANYTIME))
|
|
continue;
|
|
if (con->flags & CON_EXTENDED)
|
|
con->write(con, ext_text, ext_len);
|
|
else
|
|
con->write(con, text, len);
|
|
}
|
|
}
|
|
|
|
int printk_delay_msec __read_mostly;
|
|
|
|
static inline void printk_delay(void)
|
|
{
|
|
if (unlikely(printk_delay_msec)) {
|
|
int m = printk_delay_msec;
|
|
|
|
while (m--) {
|
|
mdelay(1);
|
|
touch_nmi_watchdog();
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Continuation lines are buffered, and not committed to the record buffer
|
|
* until the line is complete, or a race forces it. The line fragments
|
|
* though, are printed immediately to the consoles to ensure everything has
|
|
* reached the console in case of a kernel crash.
|
|
*/
|
|
static struct cont {
|
|
char buf[LOG_LINE_MAX];
|
|
size_t len; /* length == 0 means unused buffer */
|
|
struct task_struct *owner; /* task of first print*/
|
|
u64 ts_nsec; /* time of first print */
|
|
u8 level; /* log level of first message */
|
|
u8 facility; /* log facility of first message */
|
|
enum log_flags flags; /* prefix, newline flags */
|
|
} cont;
|
|
|
|
static void cont_flush(void)
|
|
{
|
|
if (cont.len == 0)
|
|
return;
|
|
|
|
log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec,
|
|
NULL, 0, cont.buf, cont.len);
|
|
cont.len = 0;
|
|
}
|
|
|
|
static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len)
|
|
{
|
|
/*
|
|
* If ext consoles are present, flush and skip in-kernel
|
|
* continuation. See nr_ext_console_drivers definition. Also, if
|
|
* the line gets too long, split it up in separate records.
|
|
*/
|
|
if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) {
|
|
cont_flush();
|
|
return false;
|
|
}
|
|
|
|
if (!cont.len) {
|
|
cont.facility = facility;
|
|
cont.level = level;
|
|
cont.owner = current;
|
|
cont.ts_nsec = local_clock();
|
|
cont.flags = flags;
|
|
}
|
|
|
|
memcpy(cont.buf + cont.len, text, len);
|
|
cont.len += len;
|
|
|
|
// The original flags come from the first line,
|
|
// but later continuations can add a newline.
|
|
if (flags & LOG_NEWLINE) {
|
|
cont.flags |= LOG_NEWLINE;
|
|
cont_flush();
|
|
}
|
|
|
|
if (cont.len > (sizeof(cont.buf) * 80) / 100)
|
|
cont_flush();
|
|
|
|
return true;
|
|
}
|
|
|
|
static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len)
|
|
{
|
|
/*
|
|
* If an earlier line was buffered, and we're a continuation
|
|
* write from the same process, try to add it to the buffer.
|
|
*/
|
|
if (cont.len) {
|
|
if (cont.owner == current && (lflags & LOG_CONT)) {
|
|
if (cont_add(facility, level, lflags, text, text_len))
|
|
return text_len;
|
|
}
|
|
/* Otherwise, make sure it's flushed */
|
|
cont_flush();
|
|
}
|
|
|
|
/* Skip empty continuation lines that couldn't be added - they just flush */
|
|
if (!text_len && (lflags & LOG_CONT))
|
|
return 0;
|
|
|
|
/* If it doesn't end in a newline, try to buffer the current line */
|
|
if (!(lflags & LOG_NEWLINE)) {
|
|
if (cont_add(facility, level, lflags, text, text_len))
|
|
return text_len;
|
|
}
|
|
|
|
/* Store it in the record log */
|
|
return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len);
|
|
}
|
|
|
|
asmlinkage int vprintk_emit(int facility, int level,
|
|
const char *dict, size_t dictlen,
|
|
const char *fmt, va_list args)
|
|
{
|
|
static char textbuf[LOG_LINE_MAX];
|
|
char *text = textbuf;
|
|
size_t text_len;
|
|
enum log_flags lflags = 0;
|
|
unsigned long flags;
|
|
int printed_len;
|
|
bool in_sched = false;
|
|
|
|
if (level == LOGLEVEL_SCHED) {
|
|
level = LOGLEVEL_DEFAULT;
|
|
in_sched = true;
|
|
}
|
|
|
|
boot_delay_msec(level);
|
|
printk_delay();
|
|
|
|
/* This stops the holder of console_sem just where we want him */
|
|
logbuf_lock_irqsave(flags);
|
|
/*
|
|
* The printf needs to come first; we need the syslog
|
|
* prefix which might be passed-in as a parameter.
|
|
*/
|
|
text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
|
|
|
|
/* mark and strip a trailing newline */
|
|
if (text_len && text[text_len-1] == '\n') {
|
|
text_len--;
|
|
lflags |= LOG_NEWLINE;
|
|
}
|
|
|
|
/* strip kernel syslog prefix and extract log level or control flags */
|
|
if (facility == 0) {
|
|
int kern_level;
|
|
|
|
while ((kern_level = printk_get_level(text)) != 0) {
|
|
switch (kern_level) {
|
|
case '0' ... '7':
|
|
if (level == LOGLEVEL_DEFAULT)
|
|
level = kern_level - '0';
|
|
/* fallthrough */
|
|
case 'd': /* KERN_DEFAULT */
|
|
lflags |= LOG_PREFIX;
|
|
break;
|
|
case 'c': /* KERN_CONT */
|
|
lflags |= LOG_CONT;
|
|
}
|
|
|
|
text_len -= 2;
|
|
text += 2;
|
|
}
|
|
}
|
|
|
|
if (level == LOGLEVEL_DEFAULT)
|
|
level = default_message_loglevel;
|
|
|
|
if (dict)
|
|
lflags |= LOG_PREFIX|LOG_NEWLINE;
|
|
|
|
printed_len = log_output(facility, level, lflags, dict, dictlen, text, text_len);
|
|
|
|
logbuf_unlock_irqrestore(flags);
|
|
|
|
/* If called from the scheduler, we can not call up(). */
|
|
if (!in_sched) {
|
|
/*
|
|
* Disable preemption to avoid being preempted while holding
|
|
* console_sem which would prevent anyone from printing to
|
|
* console
|
|
*/
|
|
preempt_disable();
|
|
/*
|
|
* Try to acquire and then immediately release the console
|
|
* semaphore. The release will print out buffers and wake up
|
|
* /dev/kmsg and syslog() users.
|
|
*/
|
|
if (console_trylock_spinning())
|
|
console_unlock();
|
|
preempt_enable();
|
|
}
|
|
|
|
return printed_len;
|
|
}
|
|
EXPORT_SYMBOL(vprintk_emit);
|
|
|
|
asmlinkage int vprintk(const char *fmt, va_list args)
|
|
{
|
|
return vprintk_func(fmt, args);
|
|
}
|
|
EXPORT_SYMBOL(vprintk);
|
|
|
|
asmlinkage int printk_emit(int facility, int level,
|
|
const char *dict, size_t dictlen,
|
|
const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(printk_emit);
|
|
|
|
int vprintk_default(const char *fmt, va_list args)
|
|
{
|
|
int r;
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
/* Allow to pass printk() to kdb but avoid a recursion. */
|
|
if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) {
|
|
r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
|
|
return r;
|
|
}
|
|
#endif
|
|
r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vprintk_default);
|
|
|
|
/**
|
|
* printk - print a kernel message
|
|
* @fmt: format string
|
|
*
|
|
* This is printk(). It can be called from any context. We want it to work.
|
|
*
|
|
* We try to grab the console_lock. If we succeed, it's easy - we log the
|
|
* output and call the console drivers. If we fail to get the semaphore, we
|
|
* place the output into the log buffer and return. The current holder of
|
|
* the console_sem will notice the new output in console_unlock(); and will
|
|
* send it to the consoles before releasing the lock.
|
|
*
|
|
* One effect of this deferred printing is that code which calls printk() and
|
|
* then changes console_loglevel may break. This is because console_loglevel
|
|
* is inspected when the actual printing occurs.
|
|
*
|
|
* See also:
|
|
* printf(3)
|
|
*
|
|
* See the vsnprintf() documentation for format string extensions over C99.
|
|
*/
|
|
asmlinkage __visible int printk(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk_func(fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(printk);
|
|
|
|
#else /* CONFIG_PRINTK */
|
|
|
|
#define LOG_LINE_MAX 0
|
|
#define PREFIX_MAX 0
|
|
|
|
static u64 syslog_seq;
|
|
static u32 syslog_idx;
|
|
static u64 console_seq;
|
|
static u32 console_idx;
|
|
static u64 log_first_seq;
|
|
static u32 log_first_idx;
|
|
static u64 log_next_seq;
|
|
static char *log_text(const struct printk_log *msg) { return NULL; }
|
|
static char *log_dict(const struct printk_log *msg) { return NULL; }
|
|
static struct printk_log *log_from_idx(u32 idx) { return NULL; }
|
|
static u32 log_next(u32 idx) { return 0; }
|
|
static ssize_t msg_print_ext_header(char *buf, size_t size,
|
|
struct printk_log *msg,
|
|
u64 seq) { return 0; }
|
|
static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
char *dict, size_t dict_len,
|
|
char *text, size_t text_len) { return 0; }
|
|
static void console_lock_spinning_enable(void) { }
|
|
static int console_lock_spinning_disable_and_check(void) { return 0; }
|
|
static void call_console_drivers(const char *ext_text, size_t ext_len,
|
|
const char *text, size_t len) {}
|
|
static size_t msg_print_text(const struct printk_log *msg,
|
|
bool syslog, char *buf, size_t size) { return 0; }
|
|
static bool suppress_message_printing(int level) { return false; }
|
|
|
|
#endif /* CONFIG_PRINTK */
|
|
|
|
#ifdef CONFIG_EARLY_PRINTK
|
|
struct console *early_console;
|
|
|
|
asmlinkage __visible void early_printk(const char *fmt, ...)
|
|
{
|
|
va_list ap;
|
|
char buf[512];
|
|
int n;
|
|
|
|
if (!early_console)
|
|
return;
|
|
|
|
va_start(ap, fmt);
|
|
n = vscnprintf(buf, sizeof(buf), fmt, ap);
|
|
va_end(ap);
|
|
|
|
early_console->write(early_console, buf, n);
|
|
}
|
|
#endif
|
|
|
|
static int __add_preferred_console(char *name, int idx, char *options,
|
|
char *brl_options)
|
|
{
|
|
struct console_cmdline *c;
|
|
int i;
|
|
|
|
/*
|
|
* See if this tty is not yet registered, and
|
|
* if we have a slot free.
|
|
*/
|
|
for (i = 0, c = console_cmdline;
|
|
i < MAX_CMDLINECONSOLES && c->name[0];
|
|
i++, c++) {
|
|
if (strcmp(c->name, name) == 0 && c->index == idx) {
|
|
if (!brl_options)
|
|
preferred_console = i;
|
|
return 0;
|
|
}
|
|
}
|
|
if (i == MAX_CMDLINECONSOLES)
|
|
return -E2BIG;
|
|
if (!brl_options)
|
|
preferred_console = i;
|
|
strlcpy(c->name, name, sizeof(c->name));
|
|
c->options = options;
|
|
braille_set_options(c, brl_options);
|
|
|
|
c->index = idx;
|
|
return 0;
|
|
}
|
|
|
|
static int __init console_msg_format_setup(char *str)
|
|
{
|
|
if (!strcmp(str, "syslog"))
|
|
console_msg_format = MSG_FORMAT_SYSLOG;
|
|
if (!strcmp(str, "default"))
|
|
console_msg_format = MSG_FORMAT_DEFAULT;
|
|
return 1;
|
|
}
|
|
__setup("console_msg_format=", console_msg_format_setup);
|
|
|
|
/*
|
|
* Set up a console. Called via do_early_param() in init/main.c
|
|
* for each "console=" parameter in the boot command line.
|
|
*/
|
|
static int __init console_setup(char *str)
|
|
{
|
|
char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
|
|
char *s, *options, *brl_options = NULL;
|
|
int idx;
|
|
|
|
if (_braille_console_setup(&str, &brl_options))
|
|
return 1;
|
|
|
|
/*
|
|
* Decode str into name, index, options.
|
|
*/
|
|
if (str[0] >= '0' && str[0] <= '9') {
|
|
strcpy(buf, "ttyS");
|
|
strncpy(buf + 4, str, sizeof(buf) - 5);
|
|
} else {
|
|
strncpy(buf, str, sizeof(buf) - 1);
|
|
}
|
|
buf[sizeof(buf) - 1] = 0;
|
|
options = strchr(str, ',');
|
|
if (options)
|
|
*(options++) = 0;
|
|
#ifdef __sparc__
|
|
if (!strcmp(str, "ttya"))
|
|
strcpy(buf, "ttyS0");
|
|
if (!strcmp(str, "ttyb"))
|
|
strcpy(buf, "ttyS1");
|
|
#endif
|
|
for (s = buf; *s; s++)
|
|
if (isdigit(*s) || *s == ',')
|
|
break;
|
|
idx = simple_strtoul(s, NULL, 10);
|
|
*s = 0;
|
|
|
|
__add_preferred_console(buf, idx, options, brl_options);
|
|
console_set_on_cmdline = 1;
|
|
return 1;
|
|
}
|
|
__setup("console=", console_setup);
|
|
|
|
/**
|
|
* add_preferred_console - add a device to the list of preferred consoles.
|
|
* @name: device name
|
|
* @idx: device index
|
|
* @options: options for this console
|
|
*
|
|
* The last preferred console added will be used for kernel messages
|
|
* and stdin/out/err for init. Normally this is used by console_setup
|
|
* above to handle user-supplied console arguments; however it can also
|
|
* be used by arch-specific code either to override the user or more
|
|
* commonly to provide a default console (ie from PROM variables) when
|
|
* the user has not supplied one.
|
|
*/
|
|
int add_preferred_console(char *name, int idx, char *options)
|
|
{
|
|
return __add_preferred_console(name, idx, options, NULL);
|
|
}
|
|
|
|
bool console_suspend_enabled = true;
|
|
EXPORT_SYMBOL(console_suspend_enabled);
|
|
|
|
static int __init console_suspend_disable(char *str)
|
|
{
|
|
console_suspend_enabled = false;
|
|
return 1;
|
|
}
|
|
__setup("no_console_suspend", console_suspend_disable);
|
|
module_param_named(console_suspend, console_suspend_enabled,
|
|
bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
|
|
" and hibernate operations");
|
|
|
|
/**
|
|
* suspend_console - suspend the console subsystem
|
|
*
|
|
* This disables printk() while we go into suspend states
|
|
*/
|
|
void suspend_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
printk("Suspending console(s) (use no_console_suspend to debug)\n");
|
|
console_lock();
|
|
console_suspended = 1;
|
|
up_console_sem();
|
|
}
|
|
|
|
void resume_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
down_console_sem();
|
|
console_suspended = 0;
|
|
console_unlock();
|
|
}
|
|
|
|
/**
|
|
* console_cpu_notify - print deferred console messages after CPU hotplug
|
|
* @cpu: unused
|
|
*
|
|
* If printk() is called from a CPU that is not online yet, the messages
|
|
* will be printed on the console only if there are CON_ANYTIME consoles.
|
|
* This function is called when a new CPU comes online (or fails to come
|
|
* up) or goes offline.
|
|
*/
|
|
static int console_cpu_notify(unsigned int cpu)
|
|
{
|
|
if (!cpuhp_tasks_frozen) {
|
|
/* If trylock fails, someone else is doing the printing */
|
|
if (console_trylock())
|
|
console_unlock();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* console_lock - lock the console system for exclusive use.
|
|
*
|
|
* Acquires a lock which guarantees that the caller has
|
|
* exclusive access to the console system and the console_drivers list.
|
|
*
|
|
* Can sleep, returns nothing.
|
|
*/
|
|
void console_lock(void)
|
|
{
|
|
might_sleep();
|
|
|
|
down_console_sem();
|
|
if (console_suspended)
|
|
return;
|
|
console_locked = 1;
|
|
console_may_schedule = 1;
|
|
}
|
|
EXPORT_SYMBOL(console_lock);
|
|
|
|
/**
|
|
* console_trylock - try to lock the console system for exclusive use.
|
|
*
|
|
* Try to acquire a lock which guarantees that the caller has exclusive
|
|
* access to the console system and the console_drivers list.
|
|
*
|
|
* returns 1 on success, and 0 on failure to acquire the lock.
|
|
*/
|
|
int console_trylock(void)
|
|
{
|
|
if (down_trylock_console_sem())
|
|
return 0;
|
|
if (console_suspended) {
|
|
up_console_sem();
|
|
return 0;
|
|
}
|
|
console_locked = 1;
|
|
console_may_schedule = 0;
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(console_trylock);
|
|
|
|
int is_console_locked(void)
|
|
{
|
|
return console_locked;
|
|
}
|
|
|
|
/*
|
|
* Check if we have any console that is capable of printing while cpu is
|
|
* booting or shutting down. Requires console_sem.
|
|
*/
|
|
static int have_callable_console(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con)
|
|
if ((con->flags & CON_ENABLED) &&
|
|
(con->flags & CON_ANYTIME))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Can we actually use the console at this time on this cpu?
|
|
*
|
|
* Console drivers may assume that per-cpu resources have been allocated. So
|
|
* unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
|
|
* call them until this CPU is officially up.
|
|
*/
|
|
static inline int can_use_console(void)
|
|
{
|
|
return cpu_online(raw_smp_processor_id()) || have_callable_console();
|
|
}
|
|
|
|
/**
|
|
* console_unlock - unlock the console system
|
|
*
|
|
* Releases the console_lock which the caller holds on the console system
|
|
* and the console driver list.
|
|
*
|
|
* While the console_lock was held, console output may have been buffered
|
|
* by printk(). If this is the case, console_unlock(); emits
|
|
* the output prior to releasing the lock.
|
|
*
|
|
* If there is output waiting, we wake /dev/kmsg and syslog() users.
|
|
*
|
|
* console_unlock(); may be called from any context.
|
|
*/
|
|
void console_unlock(void)
|
|
{
|
|
static char ext_text[CONSOLE_EXT_LOG_MAX];
|
|
static char text[LOG_LINE_MAX + PREFIX_MAX];
|
|
static u64 seen_seq;
|
|
unsigned long flags;
|
|
bool wake_klogd = false;
|
|
bool do_cond_resched, retry;
|
|
|
|
if (console_suspended) {
|
|
up_console_sem();
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Console drivers are called with interrupts disabled, so
|
|
* @console_may_schedule should be cleared before; however, we may
|
|
* end up dumping a lot of lines, for example, if called from
|
|
* console registration path, and should invoke cond_resched()
|
|
* between lines if allowable. Not doing so can cause a very long
|
|
* scheduling stall on a slow console leading to RCU stall and
|
|
* softlockup warnings which exacerbate the issue with more
|
|
* messages practically incapacitating the system.
|
|
*
|
|
* console_trylock() is not able to detect the preemptive
|
|
* context reliably. Therefore the value must be stored before
|
|
* and cleared after the the "again" goto label.
|
|
*/
|
|
do_cond_resched = console_may_schedule;
|
|
again:
|
|
console_may_schedule = 0;
|
|
|
|
/*
|
|
* We released the console_sem lock, so we need to recheck if
|
|
* cpu is online and (if not) is there at least one CON_ANYTIME
|
|
* console.
|
|
*/
|
|
if (!can_use_console()) {
|
|
console_locked = 0;
|
|
up_console_sem();
|
|
return;
|
|
}
|
|
|
|
for (;;) {
|
|
struct printk_log *msg;
|
|
size_t ext_len = 0;
|
|
size_t len;
|
|
|
|
printk_safe_enter_irqsave(flags);
|
|
raw_spin_lock(&logbuf_lock);
|
|
if (seen_seq != log_next_seq) {
|
|
wake_klogd = true;
|
|
seen_seq = log_next_seq;
|
|
}
|
|
|
|
if (console_seq < log_first_seq) {
|
|
len = sprintf(text, "** %u printk messages dropped **\n",
|
|
(unsigned)(log_first_seq - console_seq));
|
|
|
|
/* messages are gone, move to first one */
|
|
console_seq = log_first_seq;
|
|
console_idx = log_first_idx;
|
|
} else {
|
|
len = 0;
|
|
}
|
|
skip:
|
|
if (console_seq == log_next_seq)
|
|
break;
|
|
|
|
msg = log_from_idx(console_idx);
|
|
if (suppress_message_printing(msg->level)) {
|
|
/*
|
|
* Skip record we have buffered and already printed
|
|
* directly to the console when we received it, and
|
|
* record that has level above the console loglevel.
|
|
*/
|
|
console_idx = log_next(console_idx);
|
|
console_seq++;
|
|
goto skip;
|
|
}
|
|
|
|
len += msg_print_text(msg,
|
|
console_msg_format & MSG_FORMAT_SYSLOG,
|
|
text + len,
|
|
sizeof(text) - len);
|
|
if (nr_ext_console_drivers) {
|
|
ext_len = msg_print_ext_header(ext_text,
|
|
sizeof(ext_text),
|
|
msg, console_seq);
|
|
ext_len += msg_print_ext_body(ext_text + ext_len,
|
|
sizeof(ext_text) - ext_len,
|
|
log_dict(msg), msg->dict_len,
|
|
log_text(msg), msg->text_len);
|
|
}
|
|
console_idx = log_next(console_idx);
|
|
console_seq++;
|
|
raw_spin_unlock(&logbuf_lock);
|
|
|
|
/*
|
|
* While actively printing out messages, if another printk()
|
|
* were to occur on another CPU, it may wait for this one to
|
|
* finish. This task can not be preempted if there is a
|
|
* waiter waiting to take over.
|
|
*/
|
|
console_lock_spinning_enable();
|
|
|
|
stop_critical_timings(); /* don't trace print latency */
|
|
call_console_drivers(ext_text, ext_len, text, len);
|
|
start_critical_timings();
|
|
|
|
if (console_lock_spinning_disable_and_check()) {
|
|
printk_safe_exit_irqrestore(flags);
|
|
goto out;
|
|
}
|
|
|
|
printk_safe_exit_irqrestore(flags);
|
|
|
|
if (do_cond_resched)
|
|
cond_resched();
|
|
}
|
|
|
|
console_locked = 0;
|
|
|
|
/* Release the exclusive_console once it is used */
|
|
if (unlikely(exclusive_console))
|
|
exclusive_console = NULL;
|
|
|
|
raw_spin_unlock(&logbuf_lock);
|
|
|
|
up_console_sem();
|
|
|
|
/*
|
|
* Someone could have filled up the buffer again, so re-check if there's
|
|
* something to flush. In case we cannot trylock the console_sem again,
|
|
* there's a new owner and the console_unlock() from them will do the
|
|
* flush, no worries.
|
|
*/
|
|
raw_spin_lock(&logbuf_lock);
|
|
retry = console_seq != log_next_seq;
|
|
raw_spin_unlock(&logbuf_lock);
|
|
printk_safe_exit_irqrestore(flags);
|
|
|
|
if (retry && console_trylock())
|
|
goto again;
|
|
|
|
out:
|
|
if (wake_klogd)
|
|
wake_up_klogd();
|
|
}
|
|
EXPORT_SYMBOL(console_unlock);
|
|
|
|
/**
|
|
* console_conditional_schedule - yield the CPU if required
|
|
*
|
|
* If the console code is currently allowed to sleep, and
|
|
* if this CPU should yield the CPU to another task, do
|
|
* so here.
|
|
*
|
|
* Must be called within console_lock();.
|
|
*/
|
|
void __sched console_conditional_schedule(void)
|
|
{
|
|
if (console_may_schedule)
|
|
cond_resched();
|
|
}
|
|
EXPORT_SYMBOL(console_conditional_schedule);
|
|
|
|
void console_unblank(void)
|
|
{
|
|
struct console *c;
|
|
|
|
/*
|
|
* console_unblank can no longer be called in interrupt context unless
|
|
* oops_in_progress is set to 1..
|
|
*/
|
|
if (oops_in_progress) {
|
|
if (down_trylock_console_sem() != 0)
|
|
return;
|
|
} else
|
|
console_lock();
|
|
|
|
console_locked = 1;
|
|
console_may_schedule = 0;
|
|
for_each_console(c)
|
|
if ((c->flags & CON_ENABLED) && c->unblank)
|
|
c->unblank();
|
|
console_unlock();
|
|
}
|
|
|
|
/**
|
|
* console_flush_on_panic - flush console content on panic
|
|
*
|
|
* Immediately output all pending messages no matter what.
|
|
*/
|
|
void console_flush_on_panic(void)
|
|
{
|
|
/*
|
|
* If someone else is holding the console lock, trylock will fail
|
|
* and may_schedule may be set. Ignore and proceed to unlock so
|
|
* that messages are flushed out. As this can be called from any
|
|
* context and we don't want to get preempted while flushing,
|
|
* ensure may_schedule is cleared.
|
|
*/
|
|
console_trylock();
|
|
console_may_schedule = 0;
|
|
console_unlock();
|
|
}
|
|
|
|
/*
|
|
* Return the console tty driver structure and its associated index
|
|
*/
|
|
struct tty_driver *console_device(int *index)
|
|
{
|
|
struct console *c;
|
|
struct tty_driver *driver = NULL;
|
|
|
|
console_lock();
|
|
for_each_console(c) {
|
|
if (!c->device)
|
|
continue;
|
|
driver = c->device(c, index);
|
|
if (driver)
|
|
break;
|
|
}
|
|
console_unlock();
|
|
return driver;
|
|
}
|
|
|
|
/*
|
|
* Prevent further output on the passed console device so that (for example)
|
|
* serial drivers can disable console output before suspending a port, and can
|
|
* re-enable output afterwards.
|
|
*/
|
|
void console_stop(struct console *console)
|
|
{
|
|
console_lock();
|
|
console->flags &= ~CON_ENABLED;
|
|
console_unlock();
|
|
}
|
|
EXPORT_SYMBOL(console_stop);
|
|
|
|
void console_start(struct console *console)
|
|
{
|
|
console_lock();
|
|
console->flags |= CON_ENABLED;
|
|
console_unlock();
|
|
}
|
|
EXPORT_SYMBOL(console_start);
|
|
|
|
static int __read_mostly keep_bootcon;
|
|
|
|
static int __init keep_bootcon_setup(char *str)
|
|
{
|
|
keep_bootcon = 1;
|
|
pr_info("debug: skip boot console de-registration.\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("keep_bootcon", keep_bootcon_setup);
|
|
|
|
/*
|
|
* The console driver calls this routine during kernel initialization
|
|
* to register the console printing procedure with printk() and to
|
|
* print any messages that were printed by the kernel before the
|
|
* console driver was initialized.
|
|
*
|
|
* This can happen pretty early during the boot process (because of
|
|
* early_printk) - sometimes before setup_arch() completes - be careful
|
|
* of what kernel features are used - they may not be initialised yet.
|
|
*
|
|
* There are two types of consoles - bootconsoles (early_printk) and
|
|
* "real" consoles (everything which is not a bootconsole) which are
|
|
* handled differently.
|
|
* - Any number of bootconsoles can be registered at any time.
|
|
* - As soon as a "real" console is registered, all bootconsoles
|
|
* will be unregistered automatically.
|
|
* - Once a "real" console is registered, any attempt to register a
|
|
* bootconsoles will be rejected
|
|
*/
|
|
void register_console(struct console *newcon)
|
|
{
|
|
int i;
|
|
unsigned long flags;
|
|
struct console *bcon = NULL;
|
|
struct console_cmdline *c;
|
|
static bool has_preferred;
|
|
|
|
if (console_drivers)
|
|
for_each_console(bcon)
|
|
if (WARN(bcon == newcon,
|
|
"console '%s%d' already registered\n",
|
|
bcon->name, bcon->index))
|
|
return;
|
|
|
|
/*
|
|
* before we register a new CON_BOOT console, make sure we don't
|
|
* already have a valid console
|
|
*/
|
|
if (console_drivers && newcon->flags & CON_BOOT) {
|
|
/* find the last or real console */
|
|
for_each_console(bcon) {
|
|
if (!(bcon->flags & CON_BOOT)) {
|
|
pr_info("Too late to register bootconsole %s%d\n",
|
|
newcon->name, newcon->index);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (console_drivers && console_drivers->flags & CON_BOOT)
|
|
bcon = console_drivers;
|
|
|
|
if (!has_preferred || bcon || !console_drivers)
|
|
has_preferred = preferred_console >= 0;
|
|
|
|
/*
|
|
* See if we want to use this console driver. If we
|
|
* didn't select a console we take the first one
|
|
* that registers here.
|
|
*/
|
|
if (!has_preferred) {
|
|
if (newcon->index < 0)
|
|
newcon->index = 0;
|
|
if (newcon->setup == NULL ||
|
|
newcon->setup(newcon, NULL) == 0) {
|
|
newcon->flags |= CON_ENABLED;
|
|
if (newcon->device) {
|
|
newcon->flags |= CON_CONSDEV;
|
|
has_preferred = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* See if this console matches one we selected on
|
|
* the command line.
|
|
*/
|
|
for (i = 0, c = console_cmdline;
|
|
i < MAX_CMDLINECONSOLES && c->name[0];
|
|
i++, c++) {
|
|
if (!newcon->match ||
|
|
newcon->match(newcon, c->name, c->index, c->options) != 0) {
|
|
/* default matching */
|
|
BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
|
|
if (strcmp(c->name, newcon->name) != 0)
|
|
continue;
|
|
if (newcon->index >= 0 &&
|
|
newcon->index != c->index)
|
|
continue;
|
|
if (newcon->index < 0)
|
|
newcon->index = c->index;
|
|
|
|
if (_braille_register_console(newcon, c))
|
|
return;
|
|
|
|
if (newcon->setup &&
|
|
newcon->setup(newcon, c->options) != 0)
|
|
break;
|
|
}
|
|
|
|
newcon->flags |= CON_ENABLED;
|
|
if (i == preferred_console) {
|
|
newcon->flags |= CON_CONSDEV;
|
|
has_preferred = true;
|
|
}
|
|
break;
|
|
}
|
|
|
|
if (!(newcon->flags & CON_ENABLED))
|
|
return;
|
|
|
|
/*
|
|
* If we have a bootconsole, and are switching to a real console,
|
|
* don't print everything out again, since when the boot console, and
|
|
* the real console are the same physical device, it's annoying to
|
|
* see the beginning boot messages twice
|
|
*/
|
|
if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
|
|
newcon->flags &= ~CON_PRINTBUFFER;
|
|
|
|
/*
|
|
* Put this console in the list - keep the
|
|
* preferred driver at the head of the list.
|
|
*/
|
|
console_lock();
|
|
if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
|
|
newcon->next = console_drivers;
|
|
console_drivers = newcon;
|
|
if (newcon->next)
|
|
newcon->next->flags &= ~CON_CONSDEV;
|
|
} else {
|
|
newcon->next = console_drivers->next;
|
|
console_drivers->next = newcon;
|
|
}
|
|
|
|
if (newcon->flags & CON_EXTENDED)
|
|
if (!nr_ext_console_drivers++)
|
|
pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n");
|
|
|
|
if (newcon->flags & CON_PRINTBUFFER) {
|
|
/*
|
|
* console_unlock(); will print out the buffered messages
|
|
* for us.
|
|
*/
|
|
logbuf_lock_irqsave(flags);
|
|
console_seq = syslog_seq;
|
|
console_idx = syslog_idx;
|
|
logbuf_unlock_irqrestore(flags);
|
|
/*
|
|
* We're about to replay the log buffer. Only do this to the
|
|
* just-registered console to avoid excessive message spam to
|
|
* the already-registered consoles.
|
|
*/
|
|
exclusive_console = newcon;
|
|
}
|
|
console_unlock();
|
|
console_sysfs_notify();
|
|
|
|
/*
|
|
* By unregistering the bootconsoles after we enable the real console
|
|
* we get the "console xxx enabled" message on all the consoles -
|
|
* boot consoles, real consoles, etc - this is to ensure that end
|
|
* users know there might be something in the kernel's log buffer that
|
|
* went to the bootconsole (that they do not see on the real console)
|
|
*/
|
|
pr_info("%sconsole [%s%d] enabled\n",
|
|
(newcon->flags & CON_BOOT) ? "boot" : "" ,
|
|
newcon->name, newcon->index);
|
|
if (bcon &&
|
|
((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
|
|
!keep_bootcon) {
|
|
/* We need to iterate through all boot consoles, to make
|
|
* sure we print everything out, before we unregister them.
|
|
*/
|
|
for_each_console(bcon)
|
|
if (bcon->flags & CON_BOOT)
|
|
unregister_console(bcon);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(register_console);
|
|
|
|
int unregister_console(struct console *console)
|
|
{
|
|
struct console *a, *b;
|
|
int res;
|
|
|
|
pr_info("%sconsole [%s%d] disabled\n",
|
|
(console->flags & CON_BOOT) ? "boot" : "" ,
|
|
console->name, console->index);
|
|
|
|
res = _braille_unregister_console(console);
|
|
if (res)
|
|
return res;
|
|
|
|
res = 1;
|
|
console_lock();
|
|
if (console_drivers == console) {
|
|
console_drivers=console->next;
|
|
res = 0;
|
|
} else if (console_drivers) {
|
|
for (a=console_drivers->next, b=console_drivers ;
|
|
a; b=a, a=b->next) {
|
|
if (a == console) {
|
|
b->next = a->next;
|
|
res = 0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!res && (console->flags & CON_EXTENDED))
|
|
nr_ext_console_drivers--;
|
|
|
|
/*
|
|
* If this isn't the last console and it has CON_CONSDEV set, we
|
|
* need to set it on the next preferred console.
|
|
*/
|
|
if (console_drivers != NULL && console->flags & CON_CONSDEV)
|
|
console_drivers->flags |= CON_CONSDEV;
|
|
|
|
console->flags &= ~CON_ENABLED;
|
|
console_unlock();
|
|
console_sysfs_notify();
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(unregister_console);
|
|
|
|
/*
|
|
* Initialize the console device. This is called *early*, so
|
|
* we can't necessarily depend on lots of kernel help here.
|
|
* Just do some early initializations, and do the complex setup
|
|
* later.
|
|
*/
|
|
void __init console_init(void)
|
|
{
|
|
initcall_t *call;
|
|
|
|
/* Setup the default TTY line discipline. */
|
|
n_tty_init();
|
|
|
|
/*
|
|
* set up the console device so that later boot sequences can
|
|
* inform about problems etc..
|
|
*/
|
|
call = __con_initcall_start;
|
|
while (call < __con_initcall_end) {
|
|
(*call)();
|
|
call++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Some boot consoles access data that is in the init section and which will
|
|
* be discarded after the initcalls have been run. To make sure that no code
|
|
* will access this data, unregister the boot consoles in a late initcall.
|
|
*
|
|
* If for some reason, such as deferred probe or the driver being a loadable
|
|
* module, the real console hasn't registered yet at this point, there will
|
|
* be a brief interval in which no messages are logged to the console, which
|
|
* makes it difficult to diagnose problems that occur during this time.
|
|
*
|
|
* To mitigate this problem somewhat, only unregister consoles whose memory
|
|
* intersects with the init section. Note that all other boot consoles will
|
|
* get unregistred when the real preferred console is registered.
|
|
*/
|
|
static int __init printk_late_init(void)
|
|
{
|
|
struct console *con;
|
|
int ret;
|
|
|
|
for_each_console(con) {
|
|
if (!(con->flags & CON_BOOT))
|
|
continue;
|
|
|
|
/* Check addresses that might be used for enabled consoles. */
|
|
if (init_section_intersects(con, sizeof(*con)) ||
|
|
init_section_contains(con->write, 0) ||
|
|
init_section_contains(con->read, 0) ||
|
|
init_section_contains(con->device, 0) ||
|
|
init_section_contains(con->unblank, 0) ||
|
|
init_section_contains(con->data, 0)) {
|
|
/*
|
|
* Please, consider moving the reported consoles out
|
|
* of the init section.
|
|
*/
|
|
pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n",
|
|
con->name, con->index);
|
|
unregister_console(con);
|
|
}
|
|
}
|
|
ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL,
|
|
console_cpu_notify);
|
|
WARN_ON(ret < 0);
|
|
ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online",
|
|
console_cpu_notify, NULL);
|
|
WARN_ON(ret < 0);
|
|
return 0;
|
|
}
|
|
late_initcall(printk_late_init);
|
|
|
|
#if defined CONFIG_PRINTK
|
|
/*
|
|
* Delayed printk version, for scheduler-internal messages:
|
|
*/
|
|
#define PRINTK_PENDING_WAKEUP 0x01
|
|
#define PRINTK_PENDING_OUTPUT 0x02
|
|
|
|
static DEFINE_PER_CPU(int, printk_pending);
|
|
|
|
static void wake_up_klogd_work_func(struct irq_work *irq_work)
|
|
{
|
|
int pending = __this_cpu_xchg(printk_pending, 0);
|
|
|
|
if (pending & PRINTK_PENDING_OUTPUT) {
|
|
/* If trylock fails, someone else is doing the printing */
|
|
if (console_trylock())
|
|
console_unlock();
|
|
}
|
|
|
|
if (pending & PRINTK_PENDING_WAKEUP)
|
|
wake_up_interruptible(&log_wait);
|
|
}
|
|
|
|
static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
|
|
.func = wake_up_klogd_work_func,
|
|
.flags = IRQ_WORK_LAZY,
|
|
};
|
|
|
|
void wake_up_klogd(void)
|
|
{
|
|
preempt_disable();
|
|
if (waitqueue_active(&log_wait)) {
|
|
this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
|
|
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
|
|
}
|
|
preempt_enable();
|
|
}
|
|
|
|
int vprintk_deferred(const char *fmt, va_list args)
|
|
{
|
|
int r;
|
|
|
|
r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
|
|
|
|
preempt_disable();
|
|
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
|
|
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
|
|
preempt_enable();
|
|
|
|
return r;
|
|
}
|
|
|
|
int printk_deferred(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk_deferred(fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*
|
|
* printk rate limiting, lifted from the networking subsystem.
|
|
*
|
|
* This enforces a rate limit: not more than 10 kernel messages
|
|
* every 5s to make a denial-of-service attack impossible.
|
|
*/
|
|
DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
|
|
|
|
int __printk_ratelimit(const char *func)
|
|
{
|
|
return ___ratelimit(&printk_ratelimit_state, func);
|
|
}
|
|
EXPORT_SYMBOL(__printk_ratelimit);
|
|
|
|
/**
|
|
* printk_timed_ratelimit - caller-controlled printk ratelimiting
|
|
* @caller_jiffies: pointer to caller's state
|
|
* @interval_msecs: minimum interval between prints
|
|
*
|
|
* printk_timed_ratelimit() returns true if more than @interval_msecs
|
|
* milliseconds have elapsed since the last time printk_timed_ratelimit()
|
|
* returned true.
|
|
*/
|
|
bool printk_timed_ratelimit(unsigned long *caller_jiffies,
|
|
unsigned int interval_msecs)
|
|
{
|
|
unsigned long elapsed = jiffies - *caller_jiffies;
|
|
|
|
if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs))
|
|
return false;
|
|
|
|
*caller_jiffies = jiffies;
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(printk_timed_ratelimit);
|
|
|
|
static DEFINE_SPINLOCK(dump_list_lock);
|
|
static LIST_HEAD(dump_list);
|
|
|
|
/**
|
|
* kmsg_dump_register - register a kernel log dumper.
|
|
* @dumper: pointer to the kmsg_dumper structure
|
|
*
|
|
* Adds a kernel log dumper to the system. The dump callback in the
|
|
* structure will be called when the kernel oopses or panics and must be
|
|
* set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
|
|
*/
|
|
int kmsg_dump_register(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
int err = -EBUSY;
|
|
|
|
/* The dump callback needs to be set */
|
|
if (!dumper->dump)
|
|
return -EINVAL;
|
|
|
|
spin_lock_irqsave(&dump_list_lock, flags);
|
|
/* Don't allow registering multiple times */
|
|
if (!dumper->registered) {
|
|
dumper->registered = 1;
|
|
list_add_tail_rcu(&dumper->list, &dump_list);
|
|
err = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dump_list_lock, flags);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_register);
|
|
|
|
/**
|
|
* kmsg_dump_unregister - unregister a kmsg dumper.
|
|
* @dumper: pointer to the kmsg_dumper structure
|
|
*
|
|
* Removes a dump device from the system. Returns zero on success and
|
|
* %-EINVAL otherwise.
|
|
*/
|
|
int kmsg_dump_unregister(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
int err = -EINVAL;
|
|
|
|
spin_lock_irqsave(&dump_list_lock, flags);
|
|
if (dumper->registered) {
|
|
dumper->registered = 0;
|
|
list_del_rcu(&dumper->list);
|
|
err = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dump_list_lock, flags);
|
|
synchronize_rcu();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
|
|
|
|
static bool always_kmsg_dump;
|
|
module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
|
|
|
|
/**
|
|
* kmsg_dump - dump kernel log to kernel message dumpers.
|
|
* @reason: the reason (oops, panic etc) for dumping
|
|
*
|
|
* Call each of the registered dumper's dump() callback, which can
|
|
* retrieve the kmsg records with kmsg_dump_get_line() or
|
|
* kmsg_dump_get_buffer().
|
|
*/
|
|
void kmsg_dump(enum kmsg_dump_reason reason)
|
|
{
|
|
struct kmsg_dumper *dumper;
|
|
unsigned long flags;
|
|
|
|
if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
|
|
return;
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(dumper, &dump_list, list) {
|
|
if (dumper->max_reason && reason > dumper->max_reason)
|
|
continue;
|
|
|
|
/* initialize iterator with data about the stored records */
|
|
dumper->active = true;
|
|
|
|
logbuf_lock_irqsave(flags);
|
|
dumper->cur_seq = clear_seq;
|
|
dumper->cur_idx = clear_idx;
|
|
dumper->next_seq = log_next_seq;
|
|
dumper->next_idx = log_next_idx;
|
|
logbuf_unlock_irqrestore(flags);
|
|
|
|
/* invoke dumper which will iterate over records */
|
|
dumper->dump(dumper, reason);
|
|
|
|
/* reset iterator */
|
|
dumper->active = false;
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
|
|
* @dumper: registered kmsg dumper
|
|
* @syslog: include the "<4>" prefixes
|
|
* @line: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len: length of line placed into buffer
|
|
*
|
|
* Start at the beginning of the kmsg buffer, with the oldest kmsg
|
|
* record, and copy one record into the provided buffer.
|
|
*
|
|
* Consecutive calls will return the next available record moving
|
|
* towards the end of the buffer with the youngest messages.
|
|
*
|
|
* A return value of FALSE indicates that there are no more records to
|
|
* read.
|
|
*
|
|
* The function is similar to kmsg_dump_get_line(), but grabs no locks.
|
|
*/
|
|
bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
|
|
char *line, size_t size, size_t *len)
|
|
{
|
|
struct printk_log *msg;
|
|
size_t l = 0;
|
|
bool ret = false;
|
|
|
|
if (!dumper->active)
|
|
goto out;
|
|
|
|
if (dumper->cur_seq < log_first_seq) {
|
|
/* messages are gone, move to first available one */
|
|
dumper->cur_seq = log_first_seq;
|
|
dumper->cur_idx = log_first_idx;
|
|
}
|
|
|
|
/* last entry */
|
|
if (dumper->cur_seq >= log_next_seq)
|
|
goto out;
|
|
|
|
msg = log_from_idx(dumper->cur_idx);
|
|
l = msg_print_text(msg, syslog, line, size);
|
|
|
|
dumper->cur_idx = log_next(dumper->cur_idx);
|
|
dumper->cur_seq++;
|
|
ret = true;
|
|
out:
|
|
if (len)
|
|
*len = l;
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_get_line - retrieve one kmsg log line
|
|
* @dumper: registered kmsg dumper
|
|
* @syslog: include the "<4>" prefixes
|
|
* @line: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len: length of line placed into buffer
|
|
*
|
|
* Start at the beginning of the kmsg buffer, with the oldest kmsg
|
|
* record, and copy one record into the provided buffer.
|
|
*
|
|
* Consecutive calls will return the next available record moving
|
|
* towards the end of the buffer with the youngest messages.
|
|
*
|
|
* A return value of FALSE indicates that there are no more records to
|
|
* read.
|
|
*/
|
|
bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
|
|
char *line, size_t size, size_t *len)
|
|
{
|
|
unsigned long flags;
|
|
bool ret;
|
|
|
|
logbuf_lock_irqsave(flags);
|
|
ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
|
|
logbuf_unlock_irqrestore(flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
|
|
|
|
/**
|
|
* kmsg_dump_get_buffer - copy kmsg log lines
|
|
* @dumper: registered kmsg dumper
|
|
* @syslog: include the "<4>" prefixes
|
|
* @buf: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len: length of line placed into buffer
|
|
*
|
|
* Start at the end of the kmsg buffer and fill the provided buffer
|
|
* with as many of the the *youngest* kmsg records that fit into it.
|
|
* If the buffer is large enough, all available kmsg records will be
|
|
* copied with a single call.
|
|
*
|
|
* Consecutive calls will fill the buffer with the next block of
|
|
* available older records, not including the earlier retrieved ones.
|
|
*
|
|
* A return value of FALSE indicates that there are no more records to
|
|
* read.
|
|
*/
|
|
bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
|
|
char *buf, size_t size, size_t *len)
|
|
{
|
|
unsigned long flags;
|
|
u64 seq;
|
|
u32 idx;
|
|
u64 next_seq;
|
|
u32 next_idx;
|
|
size_t l = 0;
|
|
bool ret = false;
|
|
|
|
if (!dumper->active)
|
|
goto out;
|
|
|
|
logbuf_lock_irqsave(flags);
|
|
if (dumper->cur_seq < log_first_seq) {
|
|
/* messages are gone, move to first available one */
|
|
dumper->cur_seq = log_first_seq;
|
|
dumper->cur_idx = log_first_idx;
|
|
}
|
|
|
|
/* last entry */
|
|
if (dumper->cur_seq >= dumper->next_seq) {
|
|
logbuf_unlock_irqrestore(flags);
|
|
goto out;
|
|
}
|
|
|
|
/* calculate length of entire buffer */
|
|
seq = dumper->cur_seq;
|
|
idx = dumper->cur_idx;
|
|
while (seq < dumper->next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
l += msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* move first record forward until length fits into the buffer */
|
|
seq = dumper->cur_seq;
|
|
idx = dumper->cur_idx;
|
|
while (l > size && seq < dumper->next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
l -= msg_print_text(msg, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* last message in next interation */
|
|
next_seq = seq;
|
|
next_idx = idx;
|
|
|
|
l = 0;
|
|
while (seq < dumper->next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
l += msg_print_text(msg, syslog, buf + l, size - l);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
dumper->next_seq = next_seq;
|
|
dumper->next_idx = next_idx;
|
|
ret = true;
|
|
logbuf_unlock_irqrestore(flags);
|
|
out:
|
|
if (len)
|
|
*len = l;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
|
|
|
|
/**
|
|
* kmsg_dump_rewind_nolock - reset the interator (unlocked version)
|
|
* @dumper: registered kmsg dumper
|
|
*
|
|
* Reset the dumper's iterator so that kmsg_dump_get_line() and
|
|
* kmsg_dump_get_buffer() can be called again and used multiple
|
|
* times within the same dumper.dump() callback.
|
|
*
|
|
* The function is similar to kmsg_dump_rewind(), but grabs no locks.
|
|
*/
|
|
void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
|
|
{
|
|
dumper->cur_seq = clear_seq;
|
|
dumper->cur_idx = clear_idx;
|
|
dumper->next_seq = log_next_seq;
|
|
dumper->next_idx = log_next_idx;
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_rewind - reset the interator
|
|
* @dumper: registered kmsg dumper
|
|
*
|
|
* Reset the dumper's iterator so that kmsg_dump_get_line() and
|
|
* kmsg_dump_get_buffer() can be called again and used multiple
|
|
* times within the same dumper.dump() callback.
|
|
*/
|
|
void kmsg_dump_rewind(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
|
|
logbuf_lock_irqsave(flags);
|
|
kmsg_dump_rewind_nolock(dumper);
|
|
logbuf_unlock_irqrestore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
|
|
|
|
static char dump_stack_arch_desc_str[128];
|
|
|
|
/**
|
|
* dump_stack_set_arch_desc - set arch-specific str to show with task dumps
|
|
* @fmt: printf-style format string
|
|
* @...: arguments for the format string
|
|
*
|
|
* The configured string will be printed right after utsname during task
|
|
* dumps. Usually used to add arch-specific system identifiers. If an
|
|
* arch wants to make use of such an ID string, it should initialize this
|
|
* as soon as possible during boot.
|
|
*/
|
|
void __init dump_stack_set_arch_desc(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
|
|
va_start(args, fmt);
|
|
vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
|
|
fmt, args);
|
|
va_end(args);
|
|
}
|
|
|
|
/**
|
|
* dump_stack_print_info - print generic debug info for dump_stack()
|
|
* @log_lvl: log level
|
|
*
|
|
* Arch-specific dump_stack() implementations can use this function to
|
|
* print out the same debug information as the generic dump_stack().
|
|
*/
|
|
void dump_stack_print_info(const char *log_lvl)
|
|
{
|
|
printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
|
|
log_lvl, raw_smp_processor_id(), current->pid, current->comm,
|
|
print_tainted(), init_utsname()->release,
|
|
(int)strcspn(init_utsname()->version, " "),
|
|
init_utsname()->version);
|
|
|
|
if (dump_stack_arch_desc_str[0] != '\0')
|
|
printk("%sHardware name: %s\n",
|
|
log_lvl, dump_stack_arch_desc_str);
|
|
|
|
print_worker_info(log_lvl, current);
|
|
}
|
|
|
|
/**
|
|
* show_regs_print_info - print generic debug info for show_regs()
|
|
* @log_lvl: log level
|
|
*
|
|
* show_regs() implementations can use this function to print out generic
|
|
* debug information.
|
|
*/
|
|
void show_regs_print_info(const char *log_lvl)
|
|
{
|
|
dump_stack_print_info(log_lvl);
|
|
}
|
|
|
|
#endif
|