3698 lines
94 KiB
C
3698 lines
94 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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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/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/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/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/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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#include <trace/events/initcall.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/printk.h>
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#include "printk_ringbuffer.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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EXPORT_SYMBOL_GPL(console_printk);
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atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0);
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EXPORT_SYMBOL(ignore_console_lock_warning);
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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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/*
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* System may need to suppress printk message under certain
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* circumstances, like after kernel panic happens.
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*/
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int __read_mostly suppress_printk;
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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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size_t len;
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if (!str)
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return -EINVAL;
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len = str_has_prefix(str, "on");
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if (len) {
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devkmsg_log = DEVKMSG_LOG_MASK_ON;
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return len;
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}
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len = str_has_prefix(str, "off");
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if (len) {
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devkmsg_log = DEVKMSG_LOG_MASK_OFF;
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return len;
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}
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len = str_has_prefix(str, "ratelimit");
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if (len) {
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devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
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return len;
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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 *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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/* Number of registered extended console drivers. */
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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, 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 semaphore 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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static bool has_preferred_console;
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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 sequenced collection of records, each
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* containing variable length message text. Every record also contains its
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* own meta-data (@info).
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*
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* Every record meta-data carries the timestamp in microseconds, as well as
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* the standard userspace syslog level and syslog facility. The usual kernel
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* messages use LOG_KERN; userspace-injected messages always carry a matching
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* syslog facility, by default LOG_USER. The origin of every message can be
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* reliably determined that way.
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*
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* The human readable log message of a record is available in @text, the
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* length of the message text in @text_len. The stored message is not
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* terminated.
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*
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* Optionally, a record can carry a dictionary of properties (key/value
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* pairs), 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.-_]. Property names
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* and values are terminated by a '\0' character.
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*
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* Example of record values:
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* record.text_buf = "it's a line" (unterminated)
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* record.info.seq = 56
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* record.info.ts_nsec = 36863
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* record.info.text_len = 11
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* record.info.facility = 0 (LOG_KERN)
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* record.info.flags = 0
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* record.info.level = 3 (LOG_ERR)
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* record.info.caller_id = 299 (task 299)
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* record.info.dev_info.subsystem = "pci" (terminated)
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* record.info.dev_info.device = "+pci:0000:00:01.0" (terminated)
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*
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* The 'struct printk_info' buffer 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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/* syslog_lock protects syslog_* variables and write access to clear_seq. */
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static DEFINE_MUTEX(syslog_lock);
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#ifdef CONFIG_PRINTK
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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/* All 3 protected by @syslog_lock. */
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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 size_t syslog_partial;
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static bool syslog_time;
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/* All 3 protected by @console_sem. */
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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 u64 exclusive_console_stop_seq;
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static unsigned long console_dropped;
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struct latched_seq {
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seqcount_latch_t latch;
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u64 val[2];
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};
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/*
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* The next printk record to read after the last 'clear' command. There are
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* two copies (updated with seqcount_latch) so that reads can locklessly
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* access a valid value. Writers are synchronized by @syslog_lock.
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*/
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static struct latched_seq clear_seq = {
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.latch = SEQCNT_LATCH_ZERO(clear_seq.latch),
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.val[0] = 0,
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.val[1] = 0,
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};
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#ifdef CONFIG_PRINTK_CALLER
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#define PREFIX_MAX 48
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#else
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#define PREFIX_MAX 32
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#endif
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/* the maximum size of a formatted record (i.e. with prefix added per line) */
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#define CONSOLE_LOG_MAX 1024
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/* the maximum size allowed to be reserved for a record */
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#define LOG_LINE_MAX (CONSOLE_LOG_MAX - 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__(unsigned long)
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#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
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#define LOG_BUF_LEN_MAX (u32)(1 << 31)
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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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/*
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* Define the average message size. This only affects the number of
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* descriptors that will be available. Underestimating is better than
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* overestimating (too many available descriptors is better than not enough).
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*/
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#define PRB_AVGBITS 5 /* 32 character average length */
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#if CONFIG_LOG_BUF_SHIFT <= PRB_AVGBITS
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#error CONFIG_LOG_BUF_SHIFT value too small.
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#endif
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_DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS,
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PRB_AVGBITS, &__log_buf[0]);
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static struct printk_ringbuffer printk_rb_dynamic;
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static struct printk_ringbuffer *prb = &printk_rb_static;
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/*
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* We cannot access per-CPU data (e.g. per-CPU flush irq_work) before
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* per_cpu_areas are initialised. This variable is set to true when
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* it's safe to access per-CPU data.
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*/
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static bool __printk_percpu_data_ready __read_mostly;
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bool printk_percpu_data_ready(void)
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{
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return __printk_percpu_data_ready;
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}
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/* Must be called under syslog_lock. */
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static void latched_seq_write(struct latched_seq *ls, u64 val)
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{
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raw_write_seqcount_latch(&ls->latch);
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ls->val[0] = val;
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raw_write_seqcount_latch(&ls->latch);
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ls->val[1] = val;
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}
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/* Can be called from any context. */
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static u64 latched_seq_read_nolock(struct latched_seq *ls)
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{
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unsigned int seq;
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unsigned int idx;
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u64 val;
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do {
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seq = raw_read_seqcount_latch(&ls->latch);
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idx = seq & 0x1;
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val = ls->val[idx];
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} while (read_seqcount_latch_retry(&ls->latch, seq));
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return val;
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}
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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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/*
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* Define how much of the log buffer we could take at maximum. The value
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* must be greater than two. Note that only half of the buffer is available
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* when the index points to the middle.
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*/
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#define MAX_LOG_TAKE_PART 4
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static const char trunc_msg[] = "<truncated>";
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static void truncate_msg(u16 *text_len, u16 *trunc_msg_len)
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{
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/*
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* The message should not take the whole buffer. Otherwise, it might
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* get removed too soon.
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*/
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u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART;
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if (*text_len > max_text_len)
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*text_len = max_text_len;
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/* enable the warning message (if there is room) */
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*trunc_msg_len = strlen(trunc_msg);
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if (*text_len >= *trunc_msg_len)
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*text_len -= *trunc_msg_len;
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else
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*trunc_msg_len = 0;
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}
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int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
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static int syslog_action_restricted(int type)
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{
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if (dmesg_restrict)
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return 1;
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/*
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* Unless restricted, we allow "read all" and "get buffer size"
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* for everybody.
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*/
|
|
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 info_print_ext_header(char *buf, size_t size,
|
|
struct printk_info *info)
|
|
{
|
|
u64 ts_usec = info->ts_nsec;
|
|
char caller[20];
|
|
#ifdef CONFIG_PRINTK_CALLER
|
|
u32 id = info->caller_id;
|
|
|
|
snprintf(caller, sizeof(caller), ",caller=%c%u",
|
|
id & 0x80000000 ? 'C' : 'T', id & ~0x80000000);
|
|
#else
|
|
caller[0] = '\0';
|
|
#endif
|
|
|
|
do_div(ts_usec, 1000);
|
|
|
|
return scnprintf(buf, size, "%u,%llu,%llu,%c%s;",
|
|
(info->facility << 3) | info->level, info->seq,
|
|
ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller);
|
|
}
|
|
|
|
static ssize_t msg_add_ext_text(char *buf, size_t size,
|
|
const char *text, size_t text_len,
|
|
unsigned char endc)
|
|
{
|
|
char *p = buf, *e = buf + size;
|
|
size_t i;
|
|
|
|
/* escape non-printable characters */
|
|
for (i = 0; i < text_len; i++) {
|
|
unsigned char c = text[i];
|
|
|
|
if (c < ' ' || c >= 127 || c == '\\')
|
|
p += scnprintf(p, e - p, "\\x%02x", c);
|
|
else
|
|
append_char(&p, e, c);
|
|
}
|
|
append_char(&p, e, endc);
|
|
|
|
return p - buf;
|
|
}
|
|
|
|
static ssize_t msg_add_dict_text(char *buf, size_t size,
|
|
const char *key, const char *val)
|
|
{
|
|
size_t val_len = strlen(val);
|
|
ssize_t len;
|
|
|
|
if (!val_len)
|
|
return 0;
|
|
|
|
len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */
|
|
len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '=');
|
|
len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n');
|
|
|
|
return len;
|
|
}
|
|
|
|
static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
char *text, size_t text_len,
|
|
struct dev_printk_info *dev_info)
|
|
{
|
|
ssize_t len;
|
|
|
|
len = msg_add_ext_text(buf, size, text, text_len, '\n');
|
|
|
|
if (!dev_info)
|
|
goto out;
|
|
|
|
len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM",
|
|
dev_info->subsystem);
|
|
len += msg_add_dict_text(buf + len, size - len, "DEVICE",
|
|
dev_info->device);
|
|
out:
|
|
return len;
|
|
}
|
|
|
|
/* /dev/kmsg - userspace message inject/listen interface */
|
|
struct devkmsg_user {
|
|
atomic64_t seq;
|
|
struct ratelimit_state rs;
|
|
struct mutex lock;
|
|
char buf[CONSOLE_EXT_LOG_MAX];
|
|
|
|
struct printk_info info;
|
|
char text_buf[CONSOLE_EXT_LOG_MAX];
|
|
struct printk_record record;
|
|
};
|
|
|
|
static __printf(3, 4) __cold
|
|
int devkmsg_emit(int facility, int level, const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk_emit(facility, level, NULL, fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
|
|
static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
|
|
{
|
|
char *buf, *line;
|
|
int level = default_message_loglevel;
|
|
int facility = 1; /* LOG_USER */
|
|
struct file *file = iocb->ki_filp;
|
|
struct devkmsg_user *user = file->private_data;
|
|
size_t len = iov_iter_count(from);
|
|
ssize_t ret = len;
|
|
|
|
if (!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++;
|
|
line = endp;
|
|
}
|
|
}
|
|
|
|
devkmsg_emit(facility, level, "%s", line);
|
|
kfree(buf);
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t devkmsg_read(struct file *file, char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
struct printk_record *r = &user->record;
|
|
size_t len;
|
|
ssize_t ret;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
|
|
ret = mutex_lock_interruptible(&user->lock);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) {
|
|
if (file->f_flags & O_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
goto out;
|
|
}
|
|
|
|
ret = wait_event_interruptible(log_wait,
|
|
prb_read_valid(prb, atomic64_read(&user->seq), r));
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
if (r->info->seq != atomic64_read(&user->seq)) {
|
|
/* our last seen message is gone, return error and reset */
|
|
atomic64_set(&user->seq, r->info->seq);
|
|
ret = -EPIPE;
|
|
goto out;
|
|
}
|
|
|
|
len = info_print_ext_header(user->buf, sizeof(user->buf), r->info);
|
|
len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
|
|
&r->text_buf[0], r->info->text_len,
|
|
&r->info->dev_info);
|
|
|
|
atomic64_set(&user->seq, r->info->seq + 1);
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Be careful when modifying this function!!!
|
|
*
|
|
* Only few operations are supported because the device works only with the
|
|
* entire variable length messages (records). Non-standard values are
|
|
* returned in the other cases and has been this way for quite some time.
|
|
* User space applications might depend on this behavior.
|
|
*/
|
|
static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
loff_t ret = 0;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
if (offset)
|
|
return -ESPIPE;
|
|
|
|
switch (whence) {
|
|
case SEEK_SET:
|
|
/* the first record */
|
|
atomic64_set(&user->seq, prb_first_valid_seq(prb));
|
|
break;
|
|
case SEEK_DATA:
|
|
/*
|
|
* The first record after the last SYSLOG_ACTION_CLEAR,
|
|
* like issued by 'dmesg -c'. Reading /dev/kmsg itself
|
|
* changes no global state, and does not clear anything.
|
|
*/
|
|
atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq));
|
|
break;
|
|
case SEEK_END:
|
|
/* after the last record */
|
|
atomic64_set(&user->seq, prb_next_seq(prb));
|
|
break;
|
|
default:
|
|
ret = -EINVAL;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
struct printk_info info;
|
|
__poll_t ret = 0;
|
|
|
|
if (!user)
|
|
return EPOLLERR|EPOLLNVAL;
|
|
|
|
poll_wait(file, &log_wait, wait);
|
|
|
|
if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) {
|
|
/* return error when data has vanished underneath us */
|
|
if (info.seq != atomic64_read(&user->seq))
|
|
ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
|
|
else
|
|
ret = EPOLLIN|EPOLLRDNORM;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int devkmsg_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct devkmsg_user *user;
|
|
int err;
|
|
|
|
if (devkmsg_log & DEVKMSG_LOG_MASK_OFF)
|
|
return -EPERM;
|
|
|
|
/* write-only does not need any file context */
|
|
if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
|
|
err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
|
|
SYSLOG_FROM_READER);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
user = kvmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
|
|
if (!user)
|
|
return -ENOMEM;
|
|
|
|
ratelimit_default_init(&user->rs);
|
|
ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE);
|
|
|
|
mutex_init(&user->lock);
|
|
|
|
prb_rec_init_rd(&user->record, &user->info,
|
|
&user->text_buf[0], sizeof(user->text_buf));
|
|
|
|
atomic64_set(&user->seq, prb_first_valid_seq(prb));
|
|
|
|
file->private_data = user;
|
|
return 0;
|
|
}
|
|
|
|
static int devkmsg_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
|
|
if (!user)
|
|
return 0;
|
|
|
|
ratelimit_state_exit(&user->rs);
|
|
|
|
mutex_destroy(&user->lock);
|
|
kvfree(user);
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations kmsg_fops = {
|
|
.open = devkmsg_open,
|
|
.read = devkmsg_read,
|
|
.write_iter = devkmsg_write,
|
|
.llseek = devkmsg_llseek,
|
|
.poll = devkmsg_poll,
|
|
.release = devkmsg_release,
|
|
};
|
|
|
|
#ifdef CONFIG_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)
|
|
{
|
|
struct dev_printk_info *dev_info = NULL;
|
|
|
|
VMCOREINFO_SYMBOL(prb);
|
|
VMCOREINFO_SYMBOL(printk_rb_static);
|
|
VMCOREINFO_SYMBOL(clear_seq);
|
|
|
|
/*
|
|
* Export struct size and field offsets. User space tools can
|
|
* parse it and detect any changes to structure down the line.
|
|
*/
|
|
|
|
VMCOREINFO_STRUCT_SIZE(printk_ringbuffer);
|
|
VMCOREINFO_OFFSET(printk_ringbuffer, desc_ring);
|
|
VMCOREINFO_OFFSET(printk_ringbuffer, text_data_ring);
|
|
VMCOREINFO_OFFSET(printk_ringbuffer, fail);
|
|
|
|
VMCOREINFO_STRUCT_SIZE(prb_desc_ring);
|
|
VMCOREINFO_OFFSET(prb_desc_ring, count_bits);
|
|
VMCOREINFO_OFFSET(prb_desc_ring, descs);
|
|
VMCOREINFO_OFFSET(prb_desc_ring, infos);
|
|
VMCOREINFO_OFFSET(prb_desc_ring, head_id);
|
|
VMCOREINFO_OFFSET(prb_desc_ring, tail_id);
|
|
|
|
VMCOREINFO_STRUCT_SIZE(prb_desc);
|
|
VMCOREINFO_OFFSET(prb_desc, state_var);
|
|
VMCOREINFO_OFFSET(prb_desc, text_blk_lpos);
|
|
|
|
VMCOREINFO_STRUCT_SIZE(prb_data_blk_lpos);
|
|
VMCOREINFO_OFFSET(prb_data_blk_lpos, begin);
|
|
VMCOREINFO_OFFSET(prb_data_blk_lpos, next);
|
|
|
|
VMCOREINFO_STRUCT_SIZE(printk_info);
|
|
VMCOREINFO_OFFSET(printk_info, seq);
|
|
VMCOREINFO_OFFSET(printk_info, ts_nsec);
|
|
VMCOREINFO_OFFSET(printk_info, text_len);
|
|
VMCOREINFO_OFFSET(printk_info, caller_id);
|
|
VMCOREINFO_OFFSET(printk_info, dev_info);
|
|
|
|
VMCOREINFO_STRUCT_SIZE(dev_printk_info);
|
|
VMCOREINFO_OFFSET(dev_printk_info, subsystem);
|
|
VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem));
|
|
VMCOREINFO_OFFSET(dev_printk_info, device);
|
|
VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device));
|
|
|
|
VMCOREINFO_STRUCT_SIZE(prb_data_ring);
|
|
VMCOREINFO_OFFSET(prb_data_ring, size_bits);
|
|
VMCOREINFO_OFFSET(prb_data_ring, data);
|
|
VMCOREINFO_OFFSET(prb_data_ring, head_lpos);
|
|
VMCOREINFO_OFFSET(prb_data_ring, tail_lpos);
|
|
|
|
VMCOREINFO_SIZE(atomic_long_t);
|
|
VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter);
|
|
|
|
VMCOREINFO_STRUCT_SIZE(latched_seq);
|
|
VMCOREINFO_OFFSET(latched_seq, val);
|
|
}
|
|
#endif
|
|
|
|
/* requested log_buf_len from kernel cmdline */
|
|
static unsigned long __initdata new_log_buf_len;
|
|
|
|
/* we practice scaling the ring buffer by powers of 2 */
|
|
static void __init log_buf_len_update(u64 size)
|
|
{
|
|
if (size > (u64)LOG_BUF_LEN_MAX) {
|
|
size = (u64)LOG_BUF_LEN_MAX;
|
|
pr_err("log_buf over 2G is not supported.\n");
|
|
}
|
|
|
|
if (size)
|
|
size = roundup_pow_of_two(size);
|
|
if (size > log_buf_len)
|
|
new_log_buf_len = (unsigned long)size;
|
|
}
|
|
|
|
/* save requested log_buf_len since it's too early to process it */
|
|
static int __init log_buf_len_setup(char *str)
|
|
{
|
|
u64 size;
|
|
|
|
if (!str)
|
|
return -EINVAL;
|
|
|
|
size = memparse(str, &str);
|
|
|
|
log_buf_len_update(size);
|
|
|
|
return 0;
|
|
}
|
|
early_param("log_buf_len", log_buf_len_setup);
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
|
|
|
|
static void __init log_buf_add_cpu(void)
|
|
{
|
|
unsigned int cpu_extra;
|
|
|
|
/*
|
|
* archs should set up cpu_possible_bits properly with
|
|
* set_cpu_possible() after setup_arch() but just in
|
|
* case lets ensure this is valid.
|
|
*/
|
|
if (num_possible_cpus() == 1)
|
|
return;
|
|
|
|
cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
|
|
|
|
/* by default this will only continue through for large > 64 CPUs */
|
|
if (cpu_extra <= __LOG_BUF_LEN / 2)
|
|
return;
|
|
|
|
pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
|
|
__LOG_CPU_MAX_BUF_LEN);
|
|
pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
|
|
cpu_extra);
|
|
pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN);
|
|
|
|
log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
|
|
}
|
|
#else /* !CONFIG_SMP */
|
|
static inline void log_buf_add_cpu(void) {}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void __init set_percpu_data_ready(void)
|
|
{
|
|
__printk_percpu_data_ready = true;
|
|
}
|
|
|
|
static unsigned int __init add_to_rb(struct printk_ringbuffer *rb,
|
|
struct printk_record *r)
|
|
{
|
|
struct prb_reserved_entry e;
|
|
struct printk_record dest_r;
|
|
|
|
prb_rec_init_wr(&dest_r, r->info->text_len);
|
|
|
|
if (!prb_reserve(&e, rb, &dest_r))
|
|
return 0;
|
|
|
|
memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len);
|
|
dest_r.info->text_len = r->info->text_len;
|
|
dest_r.info->facility = r->info->facility;
|
|
dest_r.info->level = r->info->level;
|
|
dest_r.info->flags = r->info->flags;
|
|
dest_r.info->ts_nsec = r->info->ts_nsec;
|
|
dest_r.info->caller_id = r->info->caller_id;
|
|
memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info));
|
|
|
|
prb_final_commit(&e);
|
|
|
|
return prb_record_text_space(&e);
|
|
}
|
|
|
|
static char setup_text_buf[LOG_LINE_MAX] __initdata;
|
|
|
|
void __init setup_log_buf(int early)
|
|
{
|
|
struct printk_info *new_infos;
|
|
unsigned int new_descs_count;
|
|
struct prb_desc *new_descs;
|
|
struct printk_info info;
|
|
struct printk_record r;
|
|
unsigned int text_size;
|
|
size_t new_descs_size;
|
|
size_t new_infos_size;
|
|
unsigned long flags;
|
|
char *new_log_buf;
|
|
unsigned int free;
|
|
u64 seq;
|
|
|
|
/*
|
|
* Some archs call setup_log_buf() multiple times - first is very
|
|
* early, e.g. from setup_arch(), and second - when percpu_areas
|
|
* are initialised.
|
|
*/
|
|
if (!early)
|
|
set_percpu_data_ready();
|
|
|
|
if (log_buf != __log_buf)
|
|
return;
|
|
|
|
if (!early && !new_log_buf_len)
|
|
log_buf_add_cpu();
|
|
|
|
if (!new_log_buf_len)
|
|
return;
|
|
|
|
new_descs_count = new_log_buf_len >> PRB_AVGBITS;
|
|
if (new_descs_count == 0) {
|
|
pr_err("new_log_buf_len: %lu too small\n", new_log_buf_len);
|
|
return;
|
|
}
|
|
|
|
new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN);
|
|
if (unlikely(!new_log_buf)) {
|
|
pr_err("log_buf_len: %lu text bytes not available\n",
|
|
new_log_buf_len);
|
|
return;
|
|
}
|
|
|
|
new_descs_size = new_descs_count * sizeof(struct prb_desc);
|
|
new_descs = memblock_alloc(new_descs_size, LOG_ALIGN);
|
|
if (unlikely(!new_descs)) {
|
|
pr_err("log_buf_len: %zu desc bytes not available\n",
|
|
new_descs_size);
|
|
goto err_free_log_buf;
|
|
}
|
|
|
|
new_infos_size = new_descs_count * sizeof(struct printk_info);
|
|
new_infos = memblock_alloc(new_infos_size, LOG_ALIGN);
|
|
if (unlikely(!new_infos)) {
|
|
pr_err("log_buf_len: %zu info bytes not available\n",
|
|
new_infos_size);
|
|
goto err_free_descs;
|
|
}
|
|
|
|
prb_rec_init_rd(&r, &info, &setup_text_buf[0], sizeof(setup_text_buf));
|
|
|
|
prb_init(&printk_rb_dynamic,
|
|
new_log_buf, ilog2(new_log_buf_len),
|
|
new_descs, ilog2(new_descs_count),
|
|
new_infos);
|
|
|
|
local_irq_save(flags);
|
|
|
|
log_buf_len = new_log_buf_len;
|
|
log_buf = new_log_buf;
|
|
new_log_buf_len = 0;
|
|
|
|
free = __LOG_BUF_LEN;
|
|
prb_for_each_record(0, &printk_rb_static, seq, &r) {
|
|
text_size = add_to_rb(&printk_rb_dynamic, &r);
|
|
if (text_size > free)
|
|
free = 0;
|
|
else
|
|
free -= text_size;
|
|
}
|
|
|
|
prb = &printk_rb_dynamic;
|
|
|
|
local_irq_restore(flags);
|
|
|
|
/*
|
|
* Copy any remaining messages that might have appeared from
|
|
* NMI context after copying but before switching to the
|
|
* dynamic buffer.
|
|
*/
|
|
prb_for_each_record(seq, &printk_rb_static, seq, &r) {
|
|
text_size = add_to_rb(&printk_rb_dynamic, &r);
|
|
if (text_size > free)
|
|
free = 0;
|
|
else
|
|
free -= text_size;
|
|
}
|
|
|
|
if (seq != prb_next_seq(&printk_rb_static)) {
|
|
pr_err("dropped %llu messages\n",
|
|
prb_next_seq(&printk_rb_static) - seq);
|
|
}
|
|
|
|
pr_info("log_buf_len: %u bytes\n", log_buf_len);
|
|
pr_info("early log buf free: %u(%u%%)\n",
|
|
free, (free * 100) / __LOG_BUF_LEN);
|
|
return;
|
|
|
|
err_free_descs:
|
|
memblock_free(new_descs, new_descs_size);
|
|
err_free_log_buf:
|
|
memblock_free(new_log_buf, new_log_buf_len);
|
|
}
|
|
|
|
static bool __read_mostly ignore_loglevel;
|
|
|
|
static int __init ignore_loglevel_setup(char *str)
|
|
{
|
|
ignore_loglevel = true;
|
|
pr_info("debug: ignoring loglevel setting.\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("ignore_loglevel", ignore_loglevel_setup);
|
|
module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(ignore_loglevel,
|
|
"ignore loglevel setting (prints all kernel messages to the console)");
|
|
|
|
static bool suppress_message_printing(int level)
|
|
{
|
|
return (level >= console_loglevel && !ignore_loglevel);
|
|
}
|
|
|
|
#ifdef CONFIG_BOOT_PRINTK_DELAY
|
|
|
|
static int boot_delay; /* msecs delay after each printk during bootup */
|
|
static unsigned long long loops_per_msec; /* based on boot_delay */
|
|
|
|
static int __init boot_delay_setup(char *str)
|
|
{
|
|
unsigned long lpj;
|
|
|
|
lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
|
|
loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
|
|
|
|
get_option(&str, &boot_delay);
|
|
if (boot_delay > 10 * 1000)
|
|
boot_delay = 0;
|
|
|
|
pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
|
|
"HZ: %d, loops_per_msec: %llu\n",
|
|
boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
|
|
return 0;
|
|
}
|
|
early_param("boot_delay", boot_delay_setup);
|
|
|
|
static void boot_delay_msec(int level)
|
|
{
|
|
unsigned long long k;
|
|
unsigned long timeout;
|
|
|
|
if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING)
|
|
|| suppress_message_printing(level)) {
|
|
return;
|
|
}
|
|
|
|
k = (unsigned long long)loops_per_msec * boot_delay;
|
|
|
|
timeout = jiffies + msecs_to_jiffies(boot_delay);
|
|
while (k) {
|
|
k--;
|
|
cpu_relax();
|
|
/*
|
|
* use (volatile) jiffies to prevent
|
|
* compiler reduction; loop termination via jiffies
|
|
* is secondary and may or may not happen.
|
|
*/
|
|
if (time_after(jiffies, timeout))
|
|
break;
|
|
touch_nmi_watchdog();
|
|
}
|
|
}
|
|
#else
|
|
static inline void boot_delay_msec(int level)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
|
|
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
|
|
|
|
static size_t print_syslog(unsigned int level, char *buf)
|
|
{
|
|
return sprintf(buf, "<%u>", level);
|
|
}
|
|
|
|
static size_t print_time(u64 ts, char *buf)
|
|
{
|
|
unsigned long rem_nsec = do_div(ts, 1000000000);
|
|
|
|
return sprintf(buf, "[%5lu.%06lu]",
|
|
(unsigned long)ts, rem_nsec / 1000);
|
|
}
|
|
|
|
#ifdef CONFIG_PRINTK_CALLER
|
|
static size_t print_caller(u32 id, char *buf)
|
|
{
|
|
char caller[12];
|
|
|
|
snprintf(caller, sizeof(caller), "%c%u",
|
|
id & 0x80000000 ? 'C' : 'T', id & ~0x80000000);
|
|
return sprintf(buf, "[%6s]", caller);
|
|
}
|
|
#else
|
|
#define print_caller(id, buf) 0
|
|
#endif
|
|
|
|
static size_t info_print_prefix(const struct printk_info *info, bool syslog,
|
|
bool time, char *buf)
|
|
{
|
|
size_t len = 0;
|
|
|
|
if (syslog)
|
|
len = print_syslog((info->facility << 3) | info->level, buf);
|
|
|
|
if (time)
|
|
len += print_time(info->ts_nsec, buf + len);
|
|
|
|
len += print_caller(info->caller_id, buf + len);
|
|
|
|
if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) {
|
|
buf[len++] = ' ';
|
|
buf[len] = '\0';
|
|
}
|
|
|
|
return len;
|
|
}
|
|
|
|
/*
|
|
* Prepare the record for printing. The text is shifted within the given
|
|
* buffer to avoid a need for another one. The following operations are
|
|
* done:
|
|
*
|
|
* - Add prefix for each line.
|
|
* - Drop truncated lines that no longer fit into the buffer.
|
|
* - Add the trailing newline that has been removed in vprintk_store().
|
|
* - Add a string terminator.
|
|
*
|
|
* Since the produced string is always terminated, the maximum possible
|
|
* return value is @r->text_buf_size - 1;
|
|
*
|
|
* Return: The length of the updated/prepared text, including the added
|
|
* prefixes and the newline. The terminator is not counted. The dropped
|
|
* line(s) are not counted.
|
|
*/
|
|
static size_t record_print_text(struct printk_record *r, bool syslog,
|
|
bool time)
|
|
{
|
|
size_t text_len = r->info->text_len;
|
|
size_t buf_size = r->text_buf_size;
|
|
char *text = r->text_buf;
|
|
char prefix[PREFIX_MAX];
|
|
bool truncated = false;
|
|
size_t prefix_len;
|
|
size_t line_len;
|
|
size_t len = 0;
|
|
char *next;
|
|
|
|
/*
|
|
* If the message was truncated because the buffer was not large
|
|
* enough, treat the available text as if it were the full text.
|
|
*/
|
|
if (text_len > buf_size)
|
|
text_len = buf_size;
|
|
|
|
prefix_len = info_print_prefix(r->info, syslog, time, prefix);
|
|
|
|
/*
|
|
* @text_len: bytes of unprocessed text
|
|
* @line_len: bytes of current line _without_ newline
|
|
* @text: pointer to beginning of current line
|
|
* @len: number of bytes prepared in r->text_buf
|
|
*/
|
|
for (;;) {
|
|
next = memchr(text, '\n', text_len);
|
|
if (next) {
|
|
line_len = next - text;
|
|
} else {
|
|
/* Drop truncated line(s). */
|
|
if (truncated)
|
|
break;
|
|
line_len = text_len;
|
|
}
|
|
|
|
/*
|
|
* Truncate the text if there is not enough space to add the
|
|
* prefix and a trailing newline and a terminator.
|
|
*/
|
|
if (len + prefix_len + text_len + 1 + 1 > buf_size) {
|
|
/* Drop even the current line if no space. */
|
|
if (len + prefix_len + line_len + 1 + 1 > buf_size)
|
|
break;
|
|
|
|
text_len = buf_size - len - prefix_len - 1 - 1;
|
|
truncated = true;
|
|
}
|
|
|
|
memmove(text + prefix_len, text, text_len);
|
|
memcpy(text, prefix, prefix_len);
|
|
|
|
/*
|
|
* Increment the prepared length to include the text and
|
|
* prefix that were just moved+copied. Also increment for the
|
|
* newline at the end of this line. If this is the last line,
|
|
* there is no newline, but it will be added immediately below.
|
|
*/
|
|
len += prefix_len + line_len + 1;
|
|
if (text_len == line_len) {
|
|
/*
|
|
* This is the last line. Add the trailing newline
|
|
* removed in vprintk_store().
|
|
*/
|
|
text[prefix_len + line_len] = '\n';
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Advance beyond the added prefix and the related line with
|
|
* its newline.
|
|
*/
|
|
text += prefix_len + line_len + 1;
|
|
|
|
/*
|
|
* The remaining text has only decreased by the line with its
|
|
* newline.
|
|
*
|
|
* Note that @text_len can become zero. It happens when @text
|
|
* ended with a newline (either due to truncation or the
|
|
* original string ending with "\n\n"). The loop is correctly
|
|
* repeated and (if not truncated) an empty line with a prefix
|
|
* will be prepared.
|
|
*/
|
|
text_len -= line_len + 1;
|
|
}
|
|
|
|
/*
|
|
* If a buffer was provided, it will be terminated. Space for the
|
|
* string terminator is guaranteed to be available. The terminator is
|
|
* not counted in the return value.
|
|
*/
|
|
if (buf_size > 0)
|
|
r->text_buf[len] = 0;
|
|
|
|
return len;
|
|
}
|
|
|
|
static size_t get_record_print_text_size(struct printk_info *info,
|
|
unsigned int line_count,
|
|
bool syslog, bool time)
|
|
{
|
|
char prefix[PREFIX_MAX];
|
|
size_t prefix_len;
|
|
|
|
prefix_len = info_print_prefix(info, syslog, time, prefix);
|
|
|
|
/*
|
|
* Each line will be preceded with a prefix. The intermediate
|
|
* newlines are already within the text, but a final trailing
|
|
* newline will be added.
|
|
*/
|
|
return ((prefix_len * line_count) + info->text_len + 1);
|
|
}
|
|
|
|
/*
|
|
* Beginning with @start_seq, find the first record where it and all following
|
|
* records up to (but not including) @max_seq fit into @size.
|
|
*
|
|
* @max_seq is simply an upper bound and does not need to exist. If the caller
|
|
* does not require an upper bound, -1 can be used for @max_seq.
|
|
*/
|
|
static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size,
|
|
bool syslog, bool time)
|
|
{
|
|
struct printk_info info;
|
|
unsigned int line_count;
|
|
size_t len = 0;
|
|
u64 seq;
|
|
|
|
/* Determine the size of the records up to @max_seq. */
|
|
prb_for_each_info(start_seq, prb, seq, &info, &line_count) {
|
|
if (info.seq >= max_seq)
|
|
break;
|
|
len += get_record_print_text_size(&info, line_count, syslog, time);
|
|
}
|
|
|
|
/*
|
|
* Adjust the upper bound for the next loop to avoid subtracting
|
|
* lengths that were never added.
|
|
*/
|
|
if (seq < max_seq)
|
|
max_seq = seq;
|
|
|
|
/*
|
|
* Move first record forward until length fits into the buffer. Ignore
|
|
* newest messages that were not counted in the above cycle. Messages
|
|
* might appear and get lost in the meantime. This is a best effort
|
|
* that prevents an infinite loop that could occur with a retry.
|
|
*/
|
|
prb_for_each_info(start_seq, prb, seq, &info, &line_count) {
|
|
if (len <= size || info.seq >= max_seq)
|
|
break;
|
|
len -= get_record_print_text_size(&info, line_count, syslog, time);
|
|
}
|
|
|
|
return seq;
|
|
}
|
|
|
|
/* The caller is responsible for making sure @size is greater than 0. */
|
|
static int syslog_print(char __user *buf, int size)
|
|
{
|
|
struct printk_info info;
|
|
struct printk_record r;
|
|
char *text;
|
|
int len = 0;
|
|
u64 seq;
|
|
|
|
text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
|
|
|
|
mutex_lock(&syslog_lock);
|
|
|
|
/*
|
|
* Wait for the @syslog_seq record to be available. @syslog_seq may
|
|
* change while waiting.
|
|
*/
|
|
do {
|
|
seq = syslog_seq;
|
|
|
|
mutex_unlock(&syslog_lock);
|
|
len = wait_event_interruptible(log_wait, prb_read_valid(prb, seq, NULL));
|
|
mutex_lock(&syslog_lock);
|
|
|
|
if (len)
|
|
goto out;
|
|
} while (syslog_seq != seq);
|
|
|
|
/*
|
|
* Copy records that fit into the buffer. The above cycle makes sure
|
|
* that the first record is always available.
|
|
*/
|
|
do {
|
|
size_t n;
|
|
size_t skip;
|
|
int err;
|
|
|
|
if (!prb_read_valid(prb, syslog_seq, &r))
|
|
break;
|
|
|
|
if (r.info->seq != syslog_seq) {
|
|
/* message is gone, move to next valid one */
|
|
syslog_seq = r.info->seq;
|
|
syslog_partial = 0;
|
|
}
|
|
|
|
/*
|
|
* To keep reading/counting partial line consistent,
|
|
* use printk_time value as of the beginning of a line.
|
|
*/
|
|
if (!syslog_partial)
|
|
syslog_time = printk_time;
|
|
|
|
skip = syslog_partial;
|
|
n = record_print_text(&r, true, syslog_time);
|
|
if (n - syslog_partial <= size) {
|
|
/* message fits into buffer, move forward */
|
|
syslog_seq = r.info->seq + 1;
|
|
n -= syslog_partial;
|
|
syslog_partial = 0;
|
|
} else if (!len){
|
|
/* partial read(), remember position */
|
|
n = size;
|
|
syslog_partial += n;
|
|
} else
|
|
n = 0;
|
|
|
|
if (!n)
|
|
break;
|
|
|
|
mutex_unlock(&syslog_lock);
|
|
err = copy_to_user(buf, text + skip, n);
|
|
mutex_lock(&syslog_lock);
|
|
|
|
if (err) {
|
|
if (!len)
|
|
len = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
len += n;
|
|
size -= n;
|
|
buf += n;
|
|
} while (size);
|
|
out:
|
|
mutex_unlock(&syslog_lock);
|
|
kfree(text);
|
|
return len;
|
|
}
|
|
|
|
static int syslog_print_all(char __user *buf, int size, bool clear)
|
|
{
|
|
struct printk_info info;
|
|
struct printk_record r;
|
|
char *text;
|
|
int len = 0;
|
|
u64 seq;
|
|
bool time;
|
|
|
|
text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
time = printk_time;
|
|
/*
|
|
* Find first record that fits, including all following records,
|
|
* into the user-provided buffer for this dump.
|
|
*/
|
|
seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1,
|
|
size, true, time);
|
|
|
|
prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
|
|
|
|
len = 0;
|
|
prb_for_each_record(seq, prb, seq, &r) {
|
|
int textlen;
|
|
|
|
textlen = record_print_text(&r, true, time);
|
|
|
|
if (len + textlen > size) {
|
|
seq--;
|
|
break;
|
|
}
|
|
|
|
if (copy_to_user(buf + len, text, textlen))
|
|
len = -EFAULT;
|
|
else
|
|
len += textlen;
|
|
|
|
if (len < 0)
|
|
break;
|
|
}
|
|
|
|
if (clear) {
|
|
mutex_lock(&syslog_lock);
|
|
latched_seq_write(&clear_seq, seq);
|
|
mutex_unlock(&syslog_lock);
|
|
}
|
|
|
|
kfree(text);
|
|
return len;
|
|
}
|
|
|
|
static void syslog_clear(void)
|
|
{
|
|
mutex_lock(&syslog_lock);
|
|
latched_seq_write(&clear_seq, prb_next_seq(prb));
|
|
mutex_unlock(&syslog_lock);
|
|
}
|
|
|
|
int do_syslog(int type, char __user *buf, int len, int source)
|
|
{
|
|
struct printk_info info;
|
|
bool clear = false;
|
|
static int saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
int error;
|
|
|
|
error = check_syslog_permissions(type, source);
|
|
if (error)
|
|
return error;
|
|
|
|
switch (type) {
|
|
case SYSLOG_ACTION_CLOSE: /* Close log */
|
|
break;
|
|
case SYSLOG_ACTION_OPEN: /* Open log */
|
|
break;
|
|
case SYSLOG_ACTION_READ: /* Read from log */
|
|
if (!buf || len < 0)
|
|
return -EINVAL;
|
|
if (!len)
|
|
return 0;
|
|
if (!access_ok(buf, len))
|
|
return -EFAULT;
|
|
error = syslog_print(buf, len);
|
|
break;
|
|
/* Read/clear last kernel messages */
|
|
case SYSLOG_ACTION_READ_CLEAR:
|
|
clear = true;
|
|
fallthrough;
|
|
/* Read last kernel messages */
|
|
case SYSLOG_ACTION_READ_ALL:
|
|
if (!buf || len < 0)
|
|
return -EINVAL;
|
|
if (!len)
|
|
return 0;
|
|
if (!access_ok(buf, len))
|
|
return -EFAULT;
|
|
error = syslog_print_all(buf, len, clear);
|
|
break;
|
|
/* Clear ring buffer */
|
|
case SYSLOG_ACTION_CLEAR:
|
|
syslog_clear();
|
|
break;
|
|
/* Disable logging to console */
|
|
case SYSLOG_ACTION_CONSOLE_OFF:
|
|
if (saved_console_loglevel == LOGLEVEL_DEFAULT)
|
|
saved_console_loglevel = console_loglevel;
|
|
console_loglevel = minimum_console_loglevel;
|
|
break;
|
|
/* Enable logging to console */
|
|
case SYSLOG_ACTION_CONSOLE_ON:
|
|
if (saved_console_loglevel != LOGLEVEL_DEFAULT) {
|
|
console_loglevel = saved_console_loglevel;
|
|
saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
}
|
|
break;
|
|
/* Set level of messages printed to console */
|
|
case SYSLOG_ACTION_CONSOLE_LEVEL:
|
|
if (len < 1 || len > 8)
|
|
return -EINVAL;
|
|
if (len < minimum_console_loglevel)
|
|
len = minimum_console_loglevel;
|
|
console_loglevel = len;
|
|
/* Implicitly re-enable logging to console */
|
|
saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
break;
|
|
/* Number of chars in the log buffer */
|
|
case SYSLOG_ACTION_SIZE_UNREAD:
|
|
mutex_lock(&syslog_lock);
|
|
if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) {
|
|
/* No unread messages. */
|
|
mutex_unlock(&syslog_lock);
|
|
return 0;
|
|
}
|
|
if (info.seq != syslog_seq) {
|
|
/* messages are gone, move to first one */
|
|
syslog_seq = info.seq;
|
|
syslog_partial = 0;
|
|
}
|
|
if (source == SYSLOG_FROM_PROC) {
|
|
/*
|
|
* Short-cut for poll(/"proc/kmsg") which simply checks
|
|
* for pending data, not the size; return the count of
|
|
* records, not the length.
|
|
*/
|
|
error = prb_next_seq(prb) - syslog_seq;
|
|
} else {
|
|
bool time = syslog_partial ? syslog_time : printk_time;
|
|
unsigned int line_count;
|
|
u64 seq;
|
|
|
|
prb_for_each_info(syslog_seq, prb, seq, &info,
|
|
&line_count) {
|
|
error += get_record_print_text_size(&info, line_count,
|
|
true, time);
|
|
time = printk_time;
|
|
}
|
|
error -= syslog_partial;
|
|
}
|
|
mutex_unlock(&syslog_lock);
|
|
break;
|
|
/* Size of the log buffer */
|
|
case SYSLOG_ACTION_SIZE_BUFFER:
|
|
error = log_buf_len;
|
|
break;
|
|
default:
|
|
error = -EINVAL;
|
|
break;
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
|
|
{
|
|
return do_syslog(type, buf, len, SYSLOG_FROM_READER);
|
|
}
|
|
|
|
/*
|
|
* Special console_lock variants that help to reduce the risk of soft-lockups.
|
|
* They allow to pass console_lock to another printk() call using a busy wait.
|
|
*/
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
static struct lockdep_map console_owner_dep_map = {
|
|
.name = "console_owner"
|
|
};
|
|
#endif
|
|
|
|
static DEFINE_RAW_SPINLOCK(console_owner_lock);
|
|
static struct task_struct *console_owner;
|
|
static bool console_waiter;
|
|
|
|
/**
|
|
* console_lock_spinning_enable - mark beginning of code where another
|
|
* thread might safely busy wait
|
|
*
|
|
* This basically converts console_lock into a spinlock. This marks
|
|
* the section where the console_lock owner can not sleep, because
|
|
* there may be a waiter spinning (like a spinlock). Also it must be
|
|
* ready to hand over the lock at the end of the section.
|
|
*/
|
|
static void console_lock_spinning_enable(void)
|
|
{
|
|
raw_spin_lock(&console_owner_lock);
|
|
console_owner = current;
|
|
raw_spin_unlock(&console_owner_lock);
|
|
|
|
/* The waiter may spin on us after setting console_owner */
|
|
spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
|
|
}
|
|
|
|
/**
|
|
* console_lock_spinning_disable_and_check - mark end of code where another
|
|
* thread was able to busy wait and check if there is a waiter
|
|
*
|
|
* This is called at the end of the section where spinning is allowed.
|
|
* It has two functions. First, it is a signal that it is no longer
|
|
* safe to start busy waiting for the lock. Second, it checks if
|
|
* there is a busy waiter and passes the lock rights to her.
|
|
*
|
|
* Important: Callers lose the lock if there was a busy waiter.
|
|
* They must not touch items synchronized by console_lock
|
|
* in this case.
|
|
*
|
|
* Return: 1 if the lock rights were passed, 0 otherwise.
|
|
*/
|
|
static int console_lock_spinning_disable_and_check(void)
|
|
{
|
|
int waiter;
|
|
|
|
raw_spin_lock(&console_owner_lock);
|
|
waiter = READ_ONCE(console_waiter);
|
|
console_owner = NULL;
|
|
raw_spin_unlock(&console_owner_lock);
|
|
|
|
if (!waiter) {
|
|
spin_release(&console_owner_dep_map, _THIS_IP_);
|
|
return 0;
|
|
}
|
|
|
|
/* The waiter is now free to continue */
|
|
WRITE_ONCE(console_waiter, false);
|
|
|
|
spin_release(&console_owner_dep_map, _THIS_IP_);
|
|
|
|
/*
|
|
* Hand off console_lock to waiter. The waiter will perform
|
|
* the up(). After this, the waiter is the console_lock owner.
|
|
*/
|
|
mutex_release(&console_lock_dep_map, _THIS_IP_);
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* console_trylock_spinning - try to get console_lock by busy waiting
|
|
*
|
|
* This allows to busy wait for the console_lock when the current
|
|
* owner is running in specially marked sections. It means that
|
|
* the current owner is running and cannot reschedule until it
|
|
* is ready to lose the lock.
|
|
*
|
|
* Return: 1 if we got the lock, 0 othrewise
|
|
*/
|
|
static int console_trylock_spinning(void)
|
|
{
|
|
struct task_struct *owner = NULL;
|
|
bool waiter;
|
|
bool spin = false;
|
|
unsigned long flags;
|
|
|
|
if (console_trylock())
|
|
return 1;
|
|
|
|
printk_safe_enter_irqsave(flags);
|
|
|
|
raw_spin_lock(&console_owner_lock);
|
|
owner = READ_ONCE(console_owner);
|
|
waiter = READ_ONCE(console_waiter);
|
|
if (!waiter && owner && owner != current) {
|
|
WRITE_ONCE(console_waiter, true);
|
|
spin = true;
|
|
}
|
|
raw_spin_unlock(&console_owner_lock);
|
|
|
|
/*
|
|
* If there is an active printk() writing to the
|
|
* consoles, instead of having it write our data too,
|
|
* see if we can offload that load from the active
|
|
* printer, and do some printing ourselves.
|
|
* Go into a spin only if there isn't already a waiter
|
|
* spinning, and there is an active printer, and
|
|
* that active printer isn't us (recursive printk?).
|
|
*/
|
|
if (!spin) {
|
|
printk_safe_exit_irqrestore(flags);
|
|
return 0;
|
|
}
|
|
|
|
/* We spin waiting for the owner to release us */
|
|
spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
|
|
/* Owner will clear console_waiter on hand off */
|
|
while (READ_ONCE(console_waiter))
|
|
cpu_relax();
|
|
spin_release(&console_owner_dep_map, _THIS_IP_);
|
|
|
|
printk_safe_exit_irqrestore(flags);
|
|
/*
|
|
* The owner passed the console lock to us.
|
|
* Since we did not spin on console lock, annotate
|
|
* this as a trylock. Otherwise lockdep will
|
|
* complain.
|
|
*/
|
|
mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Call the console drivers, asking them to write out
|
|
* log_buf[start] to log_buf[end - 1].
|
|
* The console_lock must be held.
|
|
*/
|
|
static void call_console_drivers(const char *ext_text, size_t ext_len,
|
|
const char *text, size_t len)
|
|
{
|
|
static char dropped_text[64];
|
|
size_t dropped_len = 0;
|
|
struct console *con;
|
|
|
|
trace_console_rcuidle(text, len);
|
|
|
|
if (!console_drivers)
|
|
return;
|
|
|
|
if (console_dropped) {
|
|
dropped_len = snprintf(dropped_text, sizeof(dropped_text),
|
|
"** %lu printk messages dropped **\n",
|
|
console_dropped);
|
|
console_dropped = 0;
|
|
}
|
|
|
|
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 {
|
|
if (dropped_len)
|
|
con->write(con, dropped_text, dropped_len);
|
|
con->write(con, text, len);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Recursion is tracked separately on each CPU. If NMIs are supported, an
|
|
* additional NMI context per CPU is also separately tracked. Until per-CPU
|
|
* is available, a separate "early tracking" is performed.
|
|
*/
|
|
static DEFINE_PER_CPU(u8, printk_count);
|
|
static u8 printk_count_early;
|
|
#ifdef CONFIG_HAVE_NMI
|
|
static DEFINE_PER_CPU(u8, printk_count_nmi);
|
|
static u8 printk_count_nmi_early;
|
|
#endif
|
|
|
|
/*
|
|
* Recursion is limited to keep the output sane. printk() should not require
|
|
* more than 1 level of recursion (allowing, for example, printk() to trigger
|
|
* a WARN), but a higher value is used in case some printk-internal errors
|
|
* exist, such as the ringbuffer validation checks failing.
|
|
*/
|
|
#define PRINTK_MAX_RECURSION 3
|
|
|
|
/*
|
|
* Return a pointer to the dedicated counter for the CPU+context of the
|
|
* caller.
|
|
*/
|
|
static u8 *__printk_recursion_counter(void)
|
|
{
|
|
#ifdef CONFIG_HAVE_NMI
|
|
if (in_nmi()) {
|
|
if (printk_percpu_data_ready())
|
|
return this_cpu_ptr(&printk_count_nmi);
|
|
return &printk_count_nmi_early;
|
|
}
|
|
#endif
|
|
if (printk_percpu_data_ready())
|
|
return this_cpu_ptr(&printk_count);
|
|
return &printk_count_early;
|
|
}
|
|
|
|
/*
|
|
* Enter recursion tracking. Interrupts are disabled to simplify tracking.
|
|
* The caller must check the boolean return value to see if the recursion is
|
|
* allowed. On failure, interrupts are not disabled.
|
|
*
|
|
* @recursion_ptr must be a variable of type (u8 *) and is the same variable
|
|
* that is passed to printk_exit_irqrestore().
|
|
*/
|
|
#define printk_enter_irqsave(recursion_ptr, flags) \
|
|
({ \
|
|
bool success = true; \
|
|
\
|
|
typecheck(u8 *, recursion_ptr); \
|
|
local_irq_save(flags); \
|
|
(recursion_ptr) = __printk_recursion_counter(); \
|
|
if (*(recursion_ptr) > PRINTK_MAX_RECURSION) { \
|
|
local_irq_restore(flags); \
|
|
success = false; \
|
|
} else { \
|
|
(*(recursion_ptr))++; \
|
|
} \
|
|
success; \
|
|
})
|
|
|
|
/* Exit recursion tracking, restoring interrupts. */
|
|
#define printk_exit_irqrestore(recursion_ptr, flags) \
|
|
do { \
|
|
typecheck(u8 *, recursion_ptr); \
|
|
(*(recursion_ptr))--; \
|
|
local_irq_restore(flags); \
|
|
} while (0)
|
|
|
|
int printk_delay_msec __read_mostly;
|
|
|
|
static inline void printk_delay(void)
|
|
{
|
|
if (unlikely(printk_delay_msec)) {
|
|
int m = printk_delay_msec;
|
|
|
|
while (m--) {
|
|
mdelay(1);
|
|
touch_nmi_watchdog();
|
|
}
|
|
}
|
|
}
|
|
|
|
static inline u32 printk_caller_id(void)
|
|
{
|
|
return in_task() ? task_pid_nr(current) :
|
|
0x80000000 + raw_smp_processor_id();
|
|
}
|
|
|
|
/**
|
|
* printk_parse_prefix - Parse level and control flags.
|
|
*
|
|
* @text: The terminated text message.
|
|
* @level: A pointer to the current level value, will be updated.
|
|
* @flags: A pointer to the current printk_info flags, will be updated.
|
|
*
|
|
* @level may be NULL if the caller is not interested in the parsed value.
|
|
* Otherwise the variable pointed to by @level must be set to
|
|
* LOGLEVEL_DEFAULT in order to be updated with the parsed value.
|
|
*
|
|
* @flags may be NULL if the caller is not interested in the parsed value.
|
|
* Otherwise the variable pointed to by @flags will be OR'd with the parsed
|
|
* value.
|
|
*
|
|
* Return: The length of the parsed level and control flags.
|
|
*/
|
|
u16 printk_parse_prefix(const char *text, int *level,
|
|
enum printk_info_flags *flags)
|
|
{
|
|
u16 prefix_len = 0;
|
|
int kern_level;
|
|
|
|
while (*text) {
|
|
kern_level = printk_get_level(text);
|
|
if (!kern_level)
|
|
break;
|
|
|
|
switch (kern_level) {
|
|
case '0' ... '7':
|
|
if (level && *level == LOGLEVEL_DEFAULT)
|
|
*level = kern_level - '0';
|
|
break;
|
|
case 'c': /* KERN_CONT */
|
|
if (flags)
|
|
*flags |= LOG_CONT;
|
|
}
|
|
|
|
prefix_len += 2;
|
|
text += 2;
|
|
}
|
|
|
|
return prefix_len;
|
|
}
|
|
|
|
__printf(5, 0)
|
|
static u16 printk_sprint(char *text, u16 size, int facility,
|
|
enum printk_info_flags *flags, const char *fmt,
|
|
va_list args)
|
|
{
|
|
u16 text_len;
|
|
|
|
text_len = vscnprintf(text, size, fmt, args);
|
|
|
|
/* Mark and strip a trailing newline. */
|
|
if (text_len && text[text_len - 1] == '\n') {
|
|
text_len--;
|
|
*flags |= LOG_NEWLINE;
|
|
}
|
|
|
|
/* Strip log level and control flags. */
|
|
if (facility == 0) {
|
|
u16 prefix_len;
|
|
|
|
prefix_len = printk_parse_prefix(text, NULL, NULL);
|
|
if (prefix_len) {
|
|
text_len -= prefix_len;
|
|
memmove(text, text + prefix_len, text_len);
|
|
}
|
|
}
|
|
|
|
return text_len;
|
|
}
|
|
|
|
__printf(4, 0)
|
|
int vprintk_store(int facility, int level,
|
|
const struct dev_printk_info *dev_info,
|
|
const char *fmt, va_list args)
|
|
{
|
|
const u32 caller_id = printk_caller_id();
|
|
struct prb_reserved_entry e;
|
|
enum printk_info_flags flags = 0;
|
|
struct printk_record r;
|
|
unsigned long irqflags;
|
|
u16 trunc_msg_len = 0;
|
|
char prefix_buf[8];
|
|
u8 *recursion_ptr;
|
|
u16 reserve_size;
|
|
va_list args2;
|
|
u16 text_len;
|
|
int ret = 0;
|
|
u64 ts_nsec;
|
|
|
|
/*
|
|
* Since the duration of printk() can vary depending on the message
|
|
* and state of the ringbuffer, grab the timestamp now so that it is
|
|
* close to the call of printk(). This provides a more deterministic
|
|
* timestamp with respect to the caller.
|
|
*/
|
|
ts_nsec = local_clock();
|
|
|
|
if (!printk_enter_irqsave(recursion_ptr, irqflags))
|
|
return 0;
|
|
|
|
/*
|
|
* The sprintf needs to come first since the syslog prefix might be
|
|
* passed in as a parameter. An extra byte must be reserved so that
|
|
* later the vscnprintf() into the reserved buffer has room for the
|
|
* terminating '\0', which is not counted by vsnprintf().
|
|
*/
|
|
va_copy(args2, args);
|
|
reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1;
|
|
va_end(args2);
|
|
|
|
if (reserve_size > LOG_LINE_MAX)
|
|
reserve_size = LOG_LINE_MAX;
|
|
|
|
/* Extract log level or control flags. */
|
|
if (facility == 0)
|
|
printk_parse_prefix(&prefix_buf[0], &level, &flags);
|
|
|
|
if (level == LOGLEVEL_DEFAULT)
|
|
level = default_message_loglevel;
|
|
|
|
if (dev_info)
|
|
flags |= LOG_NEWLINE;
|
|
|
|
if (flags & LOG_CONT) {
|
|
prb_rec_init_wr(&r, reserve_size);
|
|
if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) {
|
|
text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size,
|
|
facility, &flags, fmt, args);
|
|
r.info->text_len += text_len;
|
|
|
|
if (flags & LOG_NEWLINE) {
|
|
r.info->flags |= LOG_NEWLINE;
|
|
prb_final_commit(&e);
|
|
} else {
|
|
prb_commit(&e);
|
|
}
|
|
|
|
ret = text_len;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Explicitly initialize the record before every prb_reserve() call.
|
|
* prb_reserve_in_last() and prb_reserve() purposely invalidate the
|
|
* structure when they fail.
|
|
*/
|
|
prb_rec_init_wr(&r, reserve_size);
|
|
if (!prb_reserve(&e, prb, &r)) {
|
|
/* truncate the message if it is too long for empty buffer */
|
|
truncate_msg(&reserve_size, &trunc_msg_len);
|
|
|
|
prb_rec_init_wr(&r, reserve_size + trunc_msg_len);
|
|
if (!prb_reserve(&e, prb, &r))
|
|
goto out;
|
|
}
|
|
|
|
/* fill message */
|
|
text_len = printk_sprint(&r.text_buf[0], reserve_size, facility, &flags, fmt, args);
|
|
if (trunc_msg_len)
|
|
memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len);
|
|
r.info->text_len = text_len + trunc_msg_len;
|
|
r.info->facility = facility;
|
|
r.info->level = level & 7;
|
|
r.info->flags = flags & 0x1f;
|
|
r.info->ts_nsec = ts_nsec;
|
|
r.info->caller_id = caller_id;
|
|
if (dev_info)
|
|
memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
|
|
|
|
/* A message without a trailing newline can be continued. */
|
|
if (!(flags & LOG_NEWLINE))
|
|
prb_commit(&e);
|
|
else
|
|
prb_final_commit(&e);
|
|
|
|
ret = text_len + trunc_msg_len;
|
|
out:
|
|
printk_exit_irqrestore(recursion_ptr, irqflags);
|
|
return ret;
|
|
}
|
|
|
|
asmlinkage int vprintk_emit(int facility, int level,
|
|
const struct dev_printk_info *dev_info,
|
|
const char *fmt, va_list args)
|
|
{
|
|
int printed_len;
|
|
bool in_sched = false;
|
|
|
|
/* Suppress unimportant messages after panic happens */
|
|
if (unlikely(suppress_printk))
|
|
return 0;
|
|
|
|
if (level == LOGLEVEL_SCHED) {
|
|
level = LOGLEVEL_DEFAULT;
|
|
in_sched = true;
|
|
}
|
|
|
|
boot_delay_msec(level);
|
|
printk_delay();
|
|
|
|
printed_len = vprintk_store(facility, level, dev_info, fmt, args);
|
|
|
|
/* 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();
|
|
}
|
|
|
|
wake_up_klogd();
|
|
return printed_len;
|
|
}
|
|
EXPORT_SYMBOL(vprintk_emit);
|
|
|
|
int vprintk_default(const char *fmt, va_list args)
|
|
{
|
|
return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
|
|
}
|
|
EXPORT_SYMBOL_GPL(vprintk_default);
|
|
|
|
asmlinkage __visible int _printk(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk(fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(_printk);
|
|
|
|
#else /* CONFIG_PRINTK */
|
|
|
|
#define CONSOLE_LOG_MAX 0
|
|
#define printk_time false
|
|
|
|
#define prb_read_valid(rb, seq, r) false
|
|
#define prb_first_valid_seq(rb) 0
|
|
|
|
static u64 syslog_seq;
|
|
static u64 console_seq;
|
|
static u64 exclusive_console_stop_seq;
|
|
static unsigned long console_dropped;
|
|
|
|
static size_t record_print_text(const struct printk_record *r,
|
|
bool syslog, bool time)
|
|
{
|
|
return 0;
|
|
}
|
|
static ssize_t info_print_ext_header(char *buf, size_t size,
|
|
struct printk_info *info)
|
|
{
|
|
return 0;
|
|
}
|
|
static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
char *text, size_t text_len,
|
|
struct dev_printk_info *dev_info) { 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 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, bool user_specified)
|
|
{
|
|
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;
|
|
if (user_specified)
|
|
c->user_specified = true;
|
|
return 0;
|
|
}
|
|
}
|
|
if (i == MAX_CMDLINECONSOLES)
|
|
return -E2BIG;
|
|
if (!brl_options)
|
|
preferred_console = i;
|
|
strlcpy(c->name, name, sizeof(c->name));
|
|
c->options = options;
|
|
c->user_specified = user_specified;
|
|
braille_set_options(c, brl_options);
|
|
|
|
c->index = idx;
|
|
return 0;
|
|
}
|
|
|
|
static int __init console_msg_format_setup(char *str)
|
|
{
|
|
if (!strcmp(str, "syslog"))
|
|
console_msg_format = MSG_FORMAT_SYSLOG;
|
|
if (!strcmp(str, "default"))
|
|
console_msg_format = MSG_FORMAT_DEFAULT;
|
|
return 1;
|
|
}
|
|
__setup("console_msg_format=", console_msg_format_setup);
|
|
|
|
/*
|
|
* Set up a console. Called via do_early_param() in init/main.c
|
|
* for each "console=" parameter in the boot command line.
|
|
*/
|
|
static int __init console_setup(char *str)
|
|
{
|
|
char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
|
|
char *s, *options, *brl_options = NULL;
|
|
int idx;
|
|
|
|
/*
|
|
* console="" or console=null have been suggested as a way to
|
|
* disable console output. Use ttynull that has been created
|
|
* for exactly this purpose.
|
|
*/
|
|
if (str[0] == 0 || strcmp(str, "null") == 0) {
|
|
__add_preferred_console("ttynull", 0, NULL, NULL, true);
|
|
return 1;
|
|
}
|
|
|
|
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, true);
|
|
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, false);
|
|
}
|
|
|
|
bool console_suspend_enabled = true;
|
|
EXPORT_SYMBOL(console_suspend_enabled);
|
|
|
|
static int __init console_suspend_disable(char *str)
|
|
{
|
|
console_suspend_enabled = false;
|
|
return 1;
|
|
}
|
|
__setup("no_console_suspend", console_suspend_disable);
|
|
module_param_named(console_suspend, console_suspend_enabled,
|
|
bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
|
|
" and hibernate operations");
|
|
|
|
static bool printk_console_no_auto_verbose;
|
|
|
|
void console_verbose(void)
|
|
{
|
|
if (console_loglevel && !printk_console_no_auto_verbose)
|
|
console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
|
|
}
|
|
EXPORT_SYMBOL_GPL(console_verbose);
|
|
|
|
module_param_named(console_no_auto_verbose, printk_console_no_auto_verbose, bool, 0644);
|
|
MODULE_PARM_DESC(console_no_auto_verbose, "Disable console loglevel raise to highest on oops/panic/etc");
|
|
|
|
/**
|
|
* suspend_console - suspend the console subsystem
|
|
*
|
|
* This disables printk() while we go into suspend states
|
|
*/
|
|
void suspend_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
pr_info("Suspending console(s) (use no_console_suspend to debug)\n");
|
|
console_lock();
|
|
console_suspended = 1;
|
|
up_console_sem();
|
|
}
|
|
|
|
void resume_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
down_console_sem();
|
|
console_suspended = 0;
|
|
console_unlock();
|
|
}
|
|
|
|
/**
|
|
* console_cpu_notify - print deferred console messages after CPU hotplug
|
|
* @cpu: unused
|
|
*
|
|
* If printk() is called from a CPU that is not online yet, the messages
|
|
* will be printed on the console only if there are CON_ANYTIME consoles.
|
|
* This function is called when a new CPU comes online (or fails to come
|
|
* up) or goes offline.
|
|
*/
|
|
static int console_cpu_notify(unsigned int cpu)
|
|
{
|
|
if (!cpuhp_tasks_frozen) {
|
|
/* If trylock fails, someone else is doing the printing */
|
|
if (console_trylock())
|
|
console_unlock();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* console_lock - lock the console system for exclusive use.
|
|
*
|
|
* Acquires a lock which guarantees that the caller has
|
|
* exclusive access to the console system and the console_drivers list.
|
|
*
|
|
* Can sleep, returns nothing.
|
|
*/
|
|
void console_lock(void)
|
|
{
|
|
might_sleep();
|
|
|
|
down_console_sem();
|
|
if (console_suspended)
|
|
return;
|
|
console_locked = 1;
|
|
console_may_schedule = 1;
|
|
}
|
|
EXPORT_SYMBOL(console_lock);
|
|
|
|
/**
|
|
* console_trylock - try to lock the console system for exclusive use.
|
|
*
|
|
* Try to acquire a lock which guarantees that the caller has exclusive
|
|
* access to the console system and the console_drivers list.
|
|
*
|
|
* returns 1 on success, and 0 on failure to acquire the lock.
|
|
*/
|
|
int console_trylock(void)
|
|
{
|
|
if (down_trylock_console_sem())
|
|
return 0;
|
|
if (console_suspended) {
|
|
up_console_sem();
|
|
return 0;
|
|
}
|
|
console_locked = 1;
|
|
console_may_schedule = 0;
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(console_trylock);
|
|
|
|
int is_console_locked(void)
|
|
{
|
|
return console_locked;
|
|
}
|
|
EXPORT_SYMBOL(is_console_locked);
|
|
|
|
/*
|
|
* Check if we have any console that is capable of printing while cpu is
|
|
* booting or shutting down. Requires console_sem.
|
|
*/
|
|
static int have_callable_console(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con)
|
|
if ((con->flags & CON_ENABLED) &&
|
|
(con->flags & CON_ANYTIME))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Can we actually use the console at this time on this cpu?
|
|
*
|
|
* Console drivers may assume that per-cpu resources have been allocated. So
|
|
* unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
|
|
* call them until this CPU is officially up.
|
|
*/
|
|
static inline int can_use_console(void)
|
|
{
|
|
return cpu_online(raw_smp_processor_id()) || have_callable_console();
|
|
}
|
|
|
|
/**
|
|
* console_unlock - unlock the console system
|
|
*
|
|
* Releases the console_lock which the caller holds on the console system
|
|
* and the console driver list.
|
|
*
|
|
* While the console_lock was held, console output may have been buffered
|
|
* by printk(). If this is the case, console_unlock(); emits
|
|
* the output prior to releasing the lock.
|
|
*
|
|
* If there is output waiting, we wake /dev/kmsg and syslog() users.
|
|
*
|
|
* console_unlock(); may be called from any context.
|
|
*/
|
|
void console_unlock(void)
|
|
{
|
|
static char ext_text[CONSOLE_EXT_LOG_MAX];
|
|
static char text[CONSOLE_LOG_MAX];
|
|
unsigned long flags;
|
|
bool do_cond_resched, retry;
|
|
struct printk_info info;
|
|
struct printk_record r;
|
|
u64 __maybe_unused next_seq;
|
|
|
|
if (console_suspended) {
|
|
up_console_sem();
|
|
return;
|
|
}
|
|
|
|
prb_rec_init_rd(&r, &info, text, sizeof(text));
|
|
|
|
/*
|
|
* 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 "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 (;;) {
|
|
size_t ext_len = 0;
|
|
int handover;
|
|
size_t len;
|
|
|
|
skip:
|
|
if (!prb_read_valid(prb, console_seq, &r))
|
|
break;
|
|
|
|
if (console_seq != r.info->seq) {
|
|
console_dropped += r.info->seq - console_seq;
|
|
console_seq = r.info->seq;
|
|
}
|
|
|
|
if (suppress_message_printing(r.info->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_seq++;
|
|
goto skip;
|
|
}
|
|
|
|
/* Output to all consoles once old messages replayed. */
|
|
if (unlikely(exclusive_console &&
|
|
console_seq >= exclusive_console_stop_seq)) {
|
|
exclusive_console = NULL;
|
|
}
|
|
|
|
/*
|
|
* Handle extended console text first because later
|
|
* record_print_text() will modify the record buffer in-place.
|
|
*/
|
|
if (nr_ext_console_drivers) {
|
|
ext_len = info_print_ext_header(ext_text,
|
|
sizeof(ext_text),
|
|
r.info);
|
|
ext_len += msg_print_ext_body(ext_text + ext_len,
|
|
sizeof(ext_text) - ext_len,
|
|
&r.text_buf[0],
|
|
r.info->text_len,
|
|
&r.info->dev_info);
|
|
}
|
|
len = record_print_text(&r,
|
|
console_msg_format & MSG_FORMAT_SYSLOG,
|
|
printk_time);
|
|
console_seq++;
|
|
|
|
/*
|
|
* While actively printing out messages, if another printk()
|
|
* were to occur on another CPU, it may wait for this one to
|
|
* finish. This task can not be preempted if there is a
|
|
* waiter waiting to take over.
|
|
*
|
|
* Interrupts are disabled because the hand over to a waiter
|
|
* must not be interrupted until the hand over is completed
|
|
* (@console_waiter is cleared).
|
|
*/
|
|
printk_safe_enter_irqsave(flags);
|
|
console_lock_spinning_enable();
|
|
|
|
stop_critical_timings(); /* don't trace print latency */
|
|
call_console_drivers(ext_text, ext_len, text, len);
|
|
start_critical_timings();
|
|
|
|
handover = console_lock_spinning_disable_and_check();
|
|
printk_safe_exit_irqrestore(flags);
|
|
if (handover)
|
|
return;
|
|
|
|
if (do_cond_resched)
|
|
cond_resched();
|
|
}
|
|
|
|
/* Get consistent value of the next-to-be-used sequence number. */
|
|
next_seq = console_seq;
|
|
|
|
console_locked = 0;
|
|
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.
|
|
*/
|
|
retry = prb_read_valid(prb, next_seq, NULL);
|
|
if (retry && console_trylock())
|
|
goto again;
|
|
}
|
|
EXPORT_SYMBOL(console_unlock);
|
|
|
|
/**
|
|
* console_conditional_schedule - yield the CPU if required
|
|
*
|
|
* If the console code is currently allowed to sleep, and
|
|
* if this CPU should yield the CPU to another task, do
|
|
* so here.
|
|
*
|
|
* Must be called within console_lock();.
|
|
*/
|
|
void __sched console_conditional_schedule(void)
|
|
{
|
|
if (console_may_schedule)
|
|
cond_resched();
|
|
}
|
|
EXPORT_SYMBOL(console_conditional_schedule);
|
|
|
|
void console_unblank(void)
|
|
{
|
|
struct console *c;
|
|
|
|
/*
|
|
* console_unblank can no longer be called in interrupt context unless
|
|
* oops_in_progress is set to 1..
|
|
*/
|
|
if (oops_in_progress) {
|
|
if (down_trylock_console_sem() != 0)
|
|
return;
|
|
} else
|
|
console_lock();
|
|
|
|
console_locked = 1;
|
|
console_may_schedule = 0;
|
|
for_each_console(c)
|
|
if ((c->flags & CON_ENABLED) && c->unblank)
|
|
c->unblank();
|
|
console_unlock();
|
|
}
|
|
|
|
/**
|
|
* console_flush_on_panic - flush console content on panic
|
|
* @mode: flush all messages in buffer or just the pending ones
|
|
*
|
|
* Immediately output all pending messages no matter what.
|
|
*/
|
|
void console_flush_on_panic(enum con_flush_mode mode)
|
|
{
|
|
/*
|
|
* If someone else is holding the console lock, trylock will fail
|
|
* and may_schedule may be set. Ignore and proceed to unlock so
|
|
* that messages are flushed out. As this can be called from any
|
|
* context and we don't want to get preempted while flushing,
|
|
* ensure may_schedule is cleared.
|
|
*/
|
|
console_trylock();
|
|
console_may_schedule = 0;
|
|
|
|
if (mode == CONSOLE_REPLAY_ALL)
|
|
console_seq = prb_first_valid_seq(prb);
|
|
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);
|
|
|
|
/*
|
|
* This is called by register_console() to try to match
|
|
* the newly registered console with any of the ones selected
|
|
* by either the command line or add_preferred_console() and
|
|
* setup/enable it.
|
|
*
|
|
* Care need to be taken with consoles that are statically
|
|
* enabled such as netconsole
|
|
*/
|
|
static int try_enable_new_console(struct console *newcon, bool user_specified)
|
|
{
|
|
struct console_cmdline *c;
|
|
int i, err;
|
|
|
|
for (i = 0, c = console_cmdline;
|
|
i < MAX_CMDLINECONSOLES && c->name[0];
|
|
i++, c++) {
|
|
if (c->user_specified != user_specified)
|
|
continue;
|
|
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 0;
|
|
|
|
if (newcon->setup &&
|
|
(err = newcon->setup(newcon, c->options)) != 0)
|
|
return err;
|
|
}
|
|
newcon->flags |= CON_ENABLED;
|
|
if (i == preferred_console) {
|
|
newcon->flags |= CON_CONSDEV;
|
|
has_preferred_console = true;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Some consoles, such as pstore and netconsole, can be enabled even
|
|
* without matching. Accept the pre-enabled consoles only when match()
|
|
* and setup() had a chance to be called.
|
|
*/
|
|
if (newcon->flags & CON_ENABLED && c->user_specified == user_specified)
|
|
return 0;
|
|
|
|
return -ENOENT;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
struct console *bcon = NULL;
|
|
int err;
|
|
|
|
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 (newcon->flags & CON_BOOT) {
|
|
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_console || bcon || !console_drivers)
|
|
has_preferred_console = 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_console) {
|
|
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_console = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* See if this console matches one we selected on the command line */
|
|
err = try_enable_new_console(newcon, true);
|
|
|
|
/* If not, try to match against the platform default(s) */
|
|
if (err == -ENOENT)
|
|
err = try_enable_new_console(newcon, false);
|
|
|
|
/* printk() messages are not printed to the Braille console. */
|
|
if (err || newcon->flags & CON_BRL)
|
|
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;
|
|
/* Ensure this flag is always set for the head of the list */
|
|
newcon->flags |= CON_CONSDEV;
|
|
} else {
|
|
newcon->next = console_drivers->next;
|
|
console_drivers->next = newcon;
|
|
}
|
|
|
|
if (newcon->flags & CON_EXTENDED)
|
|
nr_ext_console_drivers++;
|
|
|
|
if (newcon->flags & CON_PRINTBUFFER) {
|
|
/*
|
|
* console_unlock(); will print out the buffered messages
|
|
* for us.
|
|
*
|
|
* We're about to replay the log buffer. Only do this to the
|
|
* just-registered console to avoid excessive message spam to
|
|
* the already-registered consoles.
|
|
*
|
|
* Set exclusive_console with disabled interrupts to reduce
|
|
* race window with eventual console_flush_on_panic() that
|
|
* ignores console_lock.
|
|
*/
|
|
exclusive_console = newcon;
|
|
exclusive_console_stop_seq = console_seq;
|
|
|
|
/* Get a consistent copy of @syslog_seq. */
|
|
mutex_lock(&syslog_lock);
|
|
console_seq = syslog_seq;
|
|
mutex_unlock(&syslog_lock);
|
|
}
|
|
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 *con;
|
|
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 < 0)
|
|
return res;
|
|
if (res > 0)
|
|
return 0;
|
|
|
|
res = -ENODEV;
|
|
console_lock();
|
|
if (console_drivers == console) {
|
|
console_drivers=console->next;
|
|
res = 0;
|
|
} else {
|
|
for_each_console(con) {
|
|
if (con->next == console) {
|
|
con->next = console->next;
|
|
res = 0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (res)
|
|
goto out_disable_unlock;
|
|
|
|
if (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();
|
|
|
|
if (console->exit)
|
|
res = console->exit(console);
|
|
|
|
return res;
|
|
|
|
out_disable_unlock:
|
|
console->flags &= ~CON_ENABLED;
|
|
console_unlock();
|
|
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(unregister_console);
|
|
|
|
/*
|
|
* Initialize the console device. This is called *early*, so
|
|
* we can't necessarily depend on lots of kernel help here.
|
|
* Just do some early initializations, and do the complex setup
|
|
* later.
|
|
*/
|
|
void __init console_init(void)
|
|
{
|
|
int ret;
|
|
initcall_t call;
|
|
initcall_entry_t *ce;
|
|
|
|
/* Setup the default TTY line discipline. */
|
|
n_tty_init();
|
|
|
|
/*
|
|
* set up the console device so that later boot sequences can
|
|
* inform about problems etc..
|
|
*/
|
|
ce = __con_initcall_start;
|
|
trace_initcall_level("console");
|
|
while (ce < __con_initcall_end) {
|
|
call = initcall_from_entry(ce);
|
|
trace_initcall_start(call);
|
|
ret = call();
|
|
trace_initcall_finish(call, ret);
|
|
ce++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Some boot consoles access data that is in the init section and which will
|
|
* be discarded after the initcalls have been run. To make sure that no code
|
|
* will access this data, unregister the boot consoles in a late initcall.
|
|
*
|
|
* If for some reason, such as deferred probe or the driver being a loadable
|
|
* module, the real console hasn't registered yet at this point, there will
|
|
* be a brief interval in which no messages are logged to the console, which
|
|
* makes it difficult to diagnose problems that occur during this time.
|
|
*
|
|
* To mitigate this problem somewhat, only unregister consoles whose memory
|
|
* intersects with the init section. Note that all other boot consoles will
|
|
* get unregistered 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) =
|
|
IRQ_WORK_INIT_LAZY(wake_up_klogd_work_func);
|
|
|
|
void wake_up_klogd(void)
|
|
{
|
|
if (!printk_percpu_data_ready())
|
|
return;
|
|
|
|
preempt_disable();
|
|
if (waitqueue_active(&log_wait)) {
|
|
this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
|
|
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
|
|
}
|
|
preempt_enable();
|
|
}
|
|
|
|
void defer_console_output(void)
|
|
{
|
|
if (!printk_percpu_data_ready())
|
|
return;
|
|
|
|
preempt_disable();
|
|
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
|
|
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
|
|
preempt_enable();
|
|
}
|
|
|
|
int vprintk_deferred(const char *fmt, va_list args)
|
|
{
|
|
int r;
|
|
|
|
r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args);
|
|
defer_console_output();
|
|
|
|
return r;
|
|
}
|
|
|
|
int _printk_deferred(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk_deferred(fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*
|
|
* printk rate limiting, lifted from the networking subsystem.
|
|
*
|
|
* This enforces a rate limit: not more than 10 kernel messages
|
|
* every 5s to make a denial-of-service attack impossible.
|
|
*/
|
|
DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
|
|
|
|
int __printk_ratelimit(const char *func)
|
|
{
|
|
return ___ratelimit(&printk_ratelimit_state, func);
|
|
}
|
|
EXPORT_SYMBOL(__printk_ratelimit);
|
|
|
|
/**
|
|
* printk_timed_ratelimit - caller-controlled printk ratelimiting
|
|
* @caller_jiffies: pointer to caller's state
|
|
* @interval_msecs: minimum interval between prints
|
|
*
|
|
* printk_timed_ratelimit() returns true if more than @interval_msecs
|
|
* milliseconds have elapsed since the last time printk_timed_ratelimit()
|
|
* returned true.
|
|
*/
|
|
bool printk_timed_ratelimit(unsigned long *caller_jiffies,
|
|
unsigned int interval_msecs)
|
|
{
|
|
unsigned long elapsed = jiffies - *caller_jiffies;
|
|
|
|
if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs))
|
|
return false;
|
|
|
|
*caller_jiffies = jiffies;
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(printk_timed_ratelimit);
|
|
|
|
static DEFINE_SPINLOCK(dump_list_lock);
|
|
static LIST_HEAD(dump_list);
|
|
|
|
/**
|
|
* kmsg_dump_register - register a kernel log dumper.
|
|
* @dumper: pointer to the kmsg_dumper structure
|
|
*
|
|
* Adds a kernel log dumper to the system. The dump callback in the
|
|
* structure will be called when the kernel oopses or panics and must be
|
|
* set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
|
|
*/
|
|
int kmsg_dump_register(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
int err = -EBUSY;
|
|
|
|
/* The dump callback needs to be set */
|
|
if (!dumper->dump)
|
|
return -EINVAL;
|
|
|
|
spin_lock_irqsave(&dump_list_lock, flags);
|
|
/* Don't allow registering multiple times */
|
|
if (!dumper->registered) {
|
|
dumper->registered = 1;
|
|
list_add_tail_rcu(&dumper->list, &dump_list);
|
|
err = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dump_list_lock, flags);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_register);
|
|
|
|
/**
|
|
* kmsg_dump_unregister - unregister a kmsg dumper.
|
|
* @dumper: pointer to the kmsg_dumper structure
|
|
*
|
|
* Removes a dump device from the system. Returns zero on success and
|
|
* %-EINVAL otherwise.
|
|
*/
|
|
int kmsg_dump_unregister(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
int err = -EINVAL;
|
|
|
|
spin_lock_irqsave(&dump_list_lock, flags);
|
|
if (dumper->registered) {
|
|
dumper->registered = 0;
|
|
list_del_rcu(&dumper->list);
|
|
err = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dump_list_lock, flags);
|
|
synchronize_rcu();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
|
|
|
|
static bool always_kmsg_dump;
|
|
module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
|
|
|
|
const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
|
|
{
|
|
switch (reason) {
|
|
case KMSG_DUMP_PANIC:
|
|
return "Panic";
|
|
case KMSG_DUMP_OOPS:
|
|
return "Oops";
|
|
case KMSG_DUMP_EMERG:
|
|
return "Emergency";
|
|
case KMSG_DUMP_SHUTDOWN:
|
|
return "Shutdown";
|
|
default:
|
|
return "Unknown";
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_reason_str);
|
|
|
|
/**
|
|
* 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;
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(dumper, &dump_list, list) {
|
|
enum kmsg_dump_reason max_reason = dumper->max_reason;
|
|
|
|
/*
|
|
* If client has not provided a specific max_reason, default
|
|
* to KMSG_DUMP_OOPS, unless always_kmsg_dump was set.
|
|
*/
|
|
if (max_reason == KMSG_DUMP_UNDEF) {
|
|
max_reason = always_kmsg_dump ? KMSG_DUMP_MAX :
|
|
KMSG_DUMP_OOPS;
|
|
}
|
|
if (reason > max_reason)
|
|
continue;
|
|
|
|
/* invoke dumper which will iterate over records */
|
|
dumper->dump(dumper, reason);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_get_line - retrieve one kmsg log line
|
|
* @iter: kmsg dump iterator
|
|
* @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_dump_iter *iter, bool syslog,
|
|
char *line, size_t size, size_t *len)
|
|
{
|
|
u64 min_seq = latched_seq_read_nolock(&clear_seq);
|
|
struct printk_info info;
|
|
unsigned int line_count;
|
|
struct printk_record r;
|
|
size_t l = 0;
|
|
bool ret = false;
|
|
|
|
if (iter->cur_seq < min_seq)
|
|
iter->cur_seq = min_seq;
|
|
|
|
prb_rec_init_rd(&r, &info, line, size);
|
|
|
|
/* Read text or count text lines? */
|
|
if (line) {
|
|
if (!prb_read_valid(prb, iter->cur_seq, &r))
|
|
goto out;
|
|
l = record_print_text(&r, syslog, printk_time);
|
|
} else {
|
|
if (!prb_read_valid_info(prb, iter->cur_seq,
|
|
&info, &line_count)) {
|
|
goto out;
|
|
}
|
|
l = get_record_print_text_size(&info, line_count, syslog,
|
|
printk_time);
|
|
|
|
}
|
|
|
|
iter->cur_seq = r.info->seq + 1;
|
|
ret = true;
|
|
out:
|
|
if (len)
|
|
*len = l;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
|
|
|
|
/**
|
|
* kmsg_dump_get_buffer - copy kmsg log lines
|
|
* @iter: kmsg dump iterator
|
|
* @syslog: include the "<4>" prefixes
|
|
* @buf: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len_out: length of line placed into buffer
|
|
*
|
|
* Start at the end of the kmsg buffer and fill the provided buffer
|
|
* with as many of 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_dump_iter *iter, bool syslog,
|
|
char *buf, size_t size, size_t *len_out)
|
|
{
|
|
u64 min_seq = latched_seq_read_nolock(&clear_seq);
|
|
struct printk_info info;
|
|
struct printk_record r;
|
|
u64 seq;
|
|
u64 next_seq;
|
|
size_t len = 0;
|
|
bool ret = false;
|
|
bool time = printk_time;
|
|
|
|
if (!buf || !size)
|
|
goto out;
|
|
|
|
if (iter->cur_seq < min_seq)
|
|
iter->cur_seq = min_seq;
|
|
|
|
if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) {
|
|
if (info.seq != iter->cur_seq) {
|
|
/* messages are gone, move to first available one */
|
|
iter->cur_seq = info.seq;
|
|
}
|
|
}
|
|
|
|
/* last entry */
|
|
if (iter->cur_seq >= iter->next_seq)
|
|
goto out;
|
|
|
|
/*
|
|
* Find first record that fits, including all following records,
|
|
* into the user-provided buffer for this dump. Pass in size-1
|
|
* because this function (by way of record_print_text()) will
|
|
* not write more than size-1 bytes of text into @buf.
|
|
*/
|
|
seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq,
|
|
size - 1, syslog, time);
|
|
|
|
/*
|
|
* Next kmsg_dump_get_buffer() invocation will dump block of
|
|
* older records stored right before this one.
|
|
*/
|
|
next_seq = seq;
|
|
|
|
prb_rec_init_rd(&r, &info, buf, size);
|
|
|
|
len = 0;
|
|
prb_for_each_record(seq, prb, seq, &r) {
|
|
if (r.info->seq >= iter->next_seq)
|
|
break;
|
|
|
|
len += record_print_text(&r, syslog, time);
|
|
|
|
/* Adjust record to store to remaining buffer space. */
|
|
prb_rec_init_rd(&r, &info, buf + len, size - len);
|
|
}
|
|
|
|
iter->next_seq = next_seq;
|
|
ret = true;
|
|
out:
|
|
if (len_out)
|
|
*len_out = len;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
|
|
|
|
/**
|
|
* kmsg_dump_rewind - reset the iterator
|
|
* @iter: kmsg dump iterator
|
|
*
|
|
* 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_dump_iter *iter)
|
|
{
|
|
iter->cur_seq = latched_seq_read_nolock(&clear_seq);
|
|
iter->next_seq = prb_next_seq(prb);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
|
|
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
static atomic_t printk_cpulock_owner = ATOMIC_INIT(-1);
|
|
static atomic_t printk_cpulock_nested = ATOMIC_INIT(0);
|
|
|
|
/**
|
|
* __printk_wait_on_cpu_lock() - Busy wait until the printk cpu-reentrant
|
|
* spinning lock is not owned by any CPU.
|
|
*
|
|
* Context: Any context.
|
|
*/
|
|
void __printk_wait_on_cpu_lock(void)
|
|
{
|
|
do {
|
|
cpu_relax();
|
|
} while (atomic_read(&printk_cpulock_owner) != -1);
|
|
}
|
|
EXPORT_SYMBOL(__printk_wait_on_cpu_lock);
|
|
|
|
/**
|
|
* __printk_cpu_trylock() - Try to acquire the printk cpu-reentrant
|
|
* spinning lock.
|
|
*
|
|
* If no processor has the lock, the calling processor takes the lock and
|
|
* becomes the owner. If the calling processor is already the owner of the
|
|
* lock, this function succeeds immediately.
|
|
*
|
|
* Context: Any context. Expects interrupts to be disabled.
|
|
* Return: 1 on success, otherwise 0.
|
|
*/
|
|
int __printk_cpu_trylock(void)
|
|
{
|
|
int cpu;
|
|
int old;
|
|
|
|
cpu = smp_processor_id();
|
|
|
|
/*
|
|
* Guarantee loads and stores from this CPU when it is the lock owner
|
|
* are _not_ visible to the previous lock owner. This pairs with
|
|
* __printk_cpu_unlock:B.
|
|
*
|
|
* Memory barrier involvement:
|
|
*
|
|
* If __printk_cpu_trylock:A reads from __printk_cpu_unlock:B, then
|
|
* __printk_cpu_unlock:A can never read from __printk_cpu_trylock:B.
|
|
*
|
|
* Relies on:
|
|
*
|
|
* RELEASE from __printk_cpu_unlock:A to __printk_cpu_unlock:B
|
|
* of the previous CPU
|
|
* matching
|
|
* ACQUIRE from __printk_cpu_trylock:A to __printk_cpu_trylock:B
|
|
* of this CPU
|
|
*/
|
|
old = atomic_cmpxchg_acquire(&printk_cpulock_owner, -1,
|
|
cpu); /* LMM(__printk_cpu_trylock:A) */
|
|
if (old == -1) {
|
|
/*
|
|
* This CPU is now the owner and begins loading/storing
|
|
* data: LMM(__printk_cpu_trylock:B)
|
|
*/
|
|
return 1;
|
|
|
|
} else if (old == cpu) {
|
|
/* This CPU is already the owner. */
|
|
atomic_inc(&printk_cpulock_nested);
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(__printk_cpu_trylock);
|
|
|
|
/**
|
|
* __printk_cpu_unlock() - Release the printk cpu-reentrant spinning lock.
|
|
*
|
|
* The calling processor must be the owner of the lock.
|
|
*
|
|
* Context: Any context. Expects interrupts to be disabled.
|
|
*/
|
|
void __printk_cpu_unlock(void)
|
|
{
|
|
if (atomic_read(&printk_cpulock_nested)) {
|
|
atomic_dec(&printk_cpulock_nested);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* This CPU is finished loading/storing data:
|
|
* LMM(__printk_cpu_unlock:A)
|
|
*/
|
|
|
|
/*
|
|
* Guarantee loads and stores from this CPU when it was the
|
|
* lock owner are visible to the next lock owner. This pairs
|
|
* with __printk_cpu_trylock:A.
|
|
*
|
|
* Memory barrier involvement:
|
|
*
|
|
* If __printk_cpu_trylock:A reads from __printk_cpu_unlock:B,
|
|
* then __printk_cpu_trylock:B reads from __printk_cpu_unlock:A.
|
|
*
|
|
* Relies on:
|
|
*
|
|
* RELEASE from __printk_cpu_unlock:A to __printk_cpu_unlock:B
|
|
* of this CPU
|
|
* matching
|
|
* ACQUIRE from __printk_cpu_trylock:A to __printk_cpu_trylock:B
|
|
* of the next CPU
|
|
*/
|
|
atomic_set_release(&printk_cpulock_owner,
|
|
-1); /* LMM(__printk_cpu_unlock:B) */
|
|
}
|
|
EXPORT_SYMBOL(__printk_cpu_unlock);
|
|
#endif /* CONFIG_SMP */
|