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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f468908bb5
This allows us to extract from the vmcore only the messages emitted since the last time the ring buffer was cleared. We just have to make sure its value is always up-to-date, when old messages are discarded to free space in log_make_free_space() for example. Signed-off-by: Zeyu Zhao <zzy8200@gmail.com> Signed-off-by: Ivan Delalande <colona@arista.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3193 lines
81 KiB
C
3193 lines
81 KiB
C
/*
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* linux/kernel/printk.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* Modified to make sys_syslog() more flexible: added commands to
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* return the last 4k of kernel messages, regardless of whether
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* they've been read or not. Added option to suppress kernel printk's
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* to the console. Added hook for sending the console messages
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* elsewhere, in preparation for a serial line console (someday).
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* Ted Ts'o, 2/11/93.
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* Modified for sysctl support, 1/8/97, Chris Horn.
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* Fixed SMP synchronization, 08/08/99, Manfred Spraul
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* manfred@colorfullife.com
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* Rewrote bits to get rid of console_lock
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* 01Mar01 Andrew Morton
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/tty.h>
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#include <linux/tty_driver.h>
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#include <linux/console.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/nmi.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/interrupt.h> /* For in_interrupt() */
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <linux/memblock.h>
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#include <linux/syscalls.h>
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#include <linux/kexec.h>
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#include <linux/kdb.h>
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#include <linux/ratelimit.h>
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#include <linux/kmsg_dump.h>
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#include <linux/syslog.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/rculist.h>
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#include <linux/poll.h>
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#include <linux/irq_work.h>
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#include <linux/utsname.h>
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#include <linux/ctype.h>
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#include <linux/uio.h>
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#include <asm/uaccess.h>
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#include <asm-generic/sections.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/printk.h>
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#include "console_cmdline.h"
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#include "braille.h"
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int console_printk[4] = {
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CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */
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MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */
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CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */
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CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */
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};
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/*
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* Low level drivers may need that to know if they can schedule in
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* their unblank() callback or not. So let's export it.
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*/
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int oops_in_progress;
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EXPORT_SYMBOL(oops_in_progress);
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/*
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* console_sem protects the console_drivers list, and also
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* provides serialisation for access to the entire console
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* driver system.
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*/
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static DEFINE_SEMAPHORE(console_sem);
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struct console *console_drivers;
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EXPORT_SYMBOL_GPL(console_drivers);
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#ifdef CONFIG_LOCKDEP
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static struct lockdep_map console_lock_dep_map = {
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.name = "console_lock"
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};
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#endif
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/*
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* Number of registered extended console drivers.
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*
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* If extended consoles are present, in-kernel cont reassembly is disabled
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* and each fragment is stored as a separate log entry with proper
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* continuation flag so that every emitted message has full metadata. This
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* doesn't change the result for regular consoles or /proc/kmsg. For
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* /dev/kmsg, as long as the reader concatenates messages according to
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* consecutive continuation flags, the end result should be the same too.
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*/
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static int nr_ext_console_drivers;
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/*
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* Helper macros to handle lockdep when locking/unlocking console_sem. We use
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* macros instead of functions so that _RET_IP_ contains useful information.
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*/
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#define down_console_sem() do { \
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down(&console_sem);\
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mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
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} while (0)
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static int __down_trylock_console_sem(unsigned long ip)
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{
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if (down_trylock(&console_sem))
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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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#define up_console_sem() do { \
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mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
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up(&console_sem);\
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} while (0)
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/*
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* This is used for debugging the mess that is the VT code by
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* keeping track if we have the console semaphore held. It's
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* definitely not the perfect debug tool (we don't know if _WE_
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* hold it and are racing, but it helps tracking those weird code
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* paths in the console code where we end up in places I want
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* locked without the console sempahore held).
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*/
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static int console_locked, console_suspended;
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/*
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* If exclusive_console is non-NULL then only this console is to be printed to.
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*/
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static struct console *exclusive_console;
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/*
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* Array of consoles built from command line options (console=)
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*/
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#define MAX_CMDLINECONSOLES 8
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static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
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static int selected_console = -1;
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static int preferred_console = -1;
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int console_set_on_cmdline;
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EXPORT_SYMBOL(console_set_on_cmdline);
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/* Flag: console code may call schedule() */
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static int console_may_schedule;
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/*
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* The printk log buffer consists of a chain of concatenated variable
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* length records. Every record starts with a record header, containing
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* the overall length of the record.
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*
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* The heads to the first and last entry in the buffer, as well as the
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* sequence numbers of these entries are maintained when messages are
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* stored.
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*
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* If the heads indicate available messages, the length in the header
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* tells the start next message. A length == 0 for the next message
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* indicates a wrap-around to the beginning of the buffer.
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*
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* Every record carries the monotonic timestamp in microseconds, as well as
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* the standard userspace syslog level and syslog facility. The usual
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* kernel messages use LOG_KERN; userspace-injected messages always carry
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* a matching syslog facility, by default LOG_USER. The origin of every
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* message can be reliably determined that way.
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*
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* The human readable log message directly follows the message header. The
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* length of the message text is stored in the header, the stored message
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* is not terminated.
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*
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* Optionally, a message can carry a dictionary of properties (key/value pairs),
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* to provide userspace with a machine-readable message context.
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*
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* Examples for well-defined, commonly used property names are:
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* DEVICE=b12:8 device identifier
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* b12:8 block dev_t
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* c127:3 char dev_t
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* n8 netdev ifindex
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* +sound:card0 subsystem:devname
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* SUBSYSTEM=pci driver-core subsystem name
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*
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* Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
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* follows directly after a '=' character. Every property is terminated by
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* a '\0' character. The last property is not terminated.
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*
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* Example of a message structure:
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* 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
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* 0008 34 00 record is 52 bytes long
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* 000a 0b 00 text is 11 bytes long
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* 000c 1f 00 dictionary is 23 bytes long
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* 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
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* 0010 69 74 27 73 20 61 20 6c "it's a l"
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* 69 6e 65 "ine"
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* 001b 44 45 56 49 43 "DEVIC"
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* 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
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* 52 49 56 45 52 3d 62 75 "RIVER=bu"
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* 67 "g"
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* 0032 00 00 00 padding to next message header
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*
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* The 'struct printk_log' buffer header must never be directly exported to
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* userspace, it is a kernel-private implementation detail that might
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* need to be changed in the future, when the requirements change.
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*
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* /dev/kmsg exports the structured data in the following line format:
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* "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n"
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*
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* Users of the export format should ignore possible additional values
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* separated by ',', and find the message after the ';' character.
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*
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* The optional key/value pairs are attached as continuation lines starting
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* with a space character and terminated by a newline. All possible
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* non-prinatable characters are escaped in the "\xff" notation.
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*/
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enum log_flags {
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LOG_NOCONS = 1, /* already flushed, do not print to console */
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LOG_NEWLINE = 2, /* text ended with a newline */
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LOG_PREFIX = 4, /* text started with a prefix */
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LOG_CONT = 8, /* text is a fragment of a continuation line */
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};
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struct printk_log {
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u64 ts_nsec; /* timestamp in nanoseconds */
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u16 len; /* length of entire record */
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u16 text_len; /* length of text buffer */
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u16 dict_len; /* length of dictionary buffer */
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u8 facility; /* syslog facility */
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u8 flags:5; /* internal record flags */
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u8 level:3; /* syslog level */
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}
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#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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__packed __aligned(4)
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#endif
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;
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/*
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* The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
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* within the scheduler's rq lock. It must be released before calling
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* console_unlock() or anything else that might wake up a process.
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*/
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static DEFINE_RAW_SPINLOCK(logbuf_lock);
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#ifdef CONFIG_PRINTK
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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/* the next printk record to read by syslog(READ) or /proc/kmsg */
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static u64 syslog_seq;
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static u32 syslog_idx;
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static enum log_flags syslog_prev;
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static size_t syslog_partial;
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/* index and sequence number of the first record stored in the buffer */
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static u64 log_first_seq;
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static u32 log_first_idx;
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/* index and sequence number of the next record to store in the buffer */
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static u64 log_next_seq;
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static u32 log_next_idx;
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/* the next printk record to write to the console */
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static u64 console_seq;
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static u32 console_idx;
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static enum log_flags console_prev;
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/* the next printk record to read after the last 'clear' command */
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static u64 clear_seq;
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static u32 clear_idx;
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#define PREFIX_MAX 32
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#define LOG_LINE_MAX (1024 - PREFIX_MAX)
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#define LOG_LEVEL(v) ((v) & 0x07)
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#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
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/* record buffer */
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#define LOG_ALIGN __alignof__(struct printk_log)
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#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
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static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
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static char *log_buf = __log_buf;
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static u32 log_buf_len = __LOG_BUF_LEN;
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/* Return log buffer address */
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char *log_buf_addr_get(void)
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{
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return log_buf;
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}
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/* Return log buffer size */
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u32 log_buf_len_get(void)
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{
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return log_buf_len;
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}
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/* human readable text of the record */
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static char *log_text(const struct printk_log *msg)
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{
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return (char *)msg + sizeof(struct printk_log);
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}
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/* optional key/value pair dictionary attached to the record */
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static char *log_dict(const struct printk_log *msg)
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{
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return (char *)msg + sizeof(struct printk_log) + msg->text_len;
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}
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/* get record by index; idx must point to valid msg */
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static struct printk_log *log_from_idx(u32 idx)
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{
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struct printk_log *msg = (struct printk_log *)(log_buf + idx);
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/*
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* A length == 0 record is the end of buffer marker. Wrap around and
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* read the message at the start of the buffer.
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*/
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if (!msg->len)
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return (struct printk_log *)log_buf;
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return msg;
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}
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/* get next record; idx must point to valid msg */
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static u32 log_next(u32 idx)
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{
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struct printk_log *msg = (struct printk_log *)(log_buf + idx);
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/* length == 0 indicates the end of the buffer; wrap */
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/*
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* A length == 0 record is the end of buffer marker. Wrap around and
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* read the message at the start of the buffer as *this* one, and
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* return the one after that.
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*/
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if (!msg->len) {
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msg = (struct printk_log *)log_buf;
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return msg->len;
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}
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return idx + msg->len;
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}
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/*
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* Check whether there is enough free space for the given message.
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*
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* The same values of first_idx and next_idx mean that the buffer
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* is either empty or full.
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*
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* If the buffer is empty, we must respect the position of the indexes.
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* They cannot be reset to the beginning of the buffer.
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*/
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static int logbuf_has_space(u32 msg_size, bool empty)
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{
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u32 free;
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if (log_next_idx > log_first_idx || empty)
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free = max(log_buf_len - log_next_idx, log_first_idx);
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else
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free = log_first_idx - log_next_idx;
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/*
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* We need space also for an empty header that signalizes wrapping
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* of the buffer.
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*/
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return free >= msg_size + sizeof(struct printk_log);
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}
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static int log_make_free_space(u32 msg_size)
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{
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while (log_first_seq < log_next_seq &&
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!logbuf_has_space(msg_size, false)) {
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/* drop old messages until we have enough contiguous space */
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log_first_idx = log_next(log_first_idx);
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log_first_seq++;
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}
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if (clear_seq < log_first_seq) {
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clear_seq = log_first_seq;
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clear_idx = log_first_idx;
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}
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/* sequence numbers are equal, so the log buffer is empty */
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if (logbuf_has_space(msg_size, log_first_seq == log_next_seq))
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return 0;
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return -ENOMEM;
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}
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/* compute the message size including the padding bytes */
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static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
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{
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u32 size;
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size = sizeof(struct printk_log) + text_len + dict_len;
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*pad_len = (-size) & (LOG_ALIGN - 1);
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size += *pad_len;
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return size;
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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 u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
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u16 *dict_len, u32 *pad_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 */
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*trunc_msg_len = strlen(trunc_msg);
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/* disable the "dict" completely */
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*dict_len = 0;
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/* compute the size again, count also the warning message */
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return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
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}
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/* insert record into the buffer, discard old ones, update heads */
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static int log_store(int facility, int level,
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enum log_flags flags, u64 ts_nsec,
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const char *dict, u16 dict_len,
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const char *text, u16 text_len)
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{
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struct printk_log *msg;
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u32 size, pad_len;
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u16 trunc_msg_len = 0;
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/* number of '\0' padding bytes to next message */
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size = msg_used_size(text_len, dict_len, &pad_len);
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if (log_make_free_space(size)) {
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/* truncate the message if it is too long for empty buffer */
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size = truncate_msg(&text_len, &trunc_msg_len,
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&dict_len, &pad_len);
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/* survive when the log buffer is too small for trunc_msg */
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if (log_make_free_space(size))
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return 0;
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}
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if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
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/*
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* This message + an additional empty header does not fit
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* at the end of the buffer. Add an empty header with len == 0
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* to signify a wrap around.
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*/
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memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
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log_next_idx = 0;
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}
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/* fill message */
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msg = (struct printk_log *)(log_buf + log_next_idx);
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memcpy(log_text(msg), text, text_len);
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msg->text_len = text_len;
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if (trunc_msg_len) {
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memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
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msg->text_len += trunc_msg_len;
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}
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memcpy(log_dict(msg), dict, dict_len);
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msg->dict_len = dict_len;
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msg->facility = facility;
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msg->level = level & 7;
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msg->flags = flags & 0x1f;
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if (ts_nsec > 0)
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msg->ts_nsec = ts_nsec;
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else
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msg->ts_nsec = local_clock();
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memset(log_dict(msg) + dict_len, 0, pad_len);
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msg->len = size;
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/* insert message */
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log_next_idx += msg->len;
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log_next_seq++;
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|
return msg->text_len;
|
|
}
|
|
|
|
int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
|
|
|
|
static int syslog_action_restricted(int type)
|
|
{
|
|
if (dmesg_restrict)
|
|
return 1;
|
|
/*
|
|
* Unless restricted, we allow "read all" and "get buffer size"
|
|
* for everybody.
|
|
*/
|
|
return type != SYSLOG_ACTION_READ_ALL &&
|
|
type != SYSLOG_ACTION_SIZE_BUFFER;
|
|
}
|
|
|
|
int check_syslog_permissions(int type, 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);
|
|
}
|
|
EXPORT_SYMBOL_GPL(check_syslog_permissions);
|
|
|
|
static void append_char(char **pp, char *e, char c)
|
|
{
|
|
if (*pp < e)
|
|
*(*pp)++ = c;
|
|
}
|
|
|
|
static ssize_t msg_print_ext_header(char *buf, size_t size,
|
|
struct printk_log *msg, u64 seq,
|
|
enum log_flags prev_flags)
|
|
{
|
|
u64 ts_usec = msg->ts_nsec;
|
|
char cont = '-';
|
|
|
|
do_div(ts_usec, 1000);
|
|
|
|
/*
|
|
* If we couldn't merge continuation line fragments during the print,
|
|
* export the stored flags to allow an optional external merge of the
|
|
* records. Merging the records isn't always neccessarily correct, like
|
|
* when we hit a race during printing. In most cases though, it produces
|
|
* better readable output. 'c' in the record flags mark the first
|
|
* fragment of a line, '+' the following.
|
|
*/
|
|
if (msg->flags & LOG_CONT && !(prev_flags & LOG_CONT))
|
|
cont = 'c';
|
|
else if ((msg->flags & LOG_CONT) ||
|
|
((prev_flags & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
|
|
cont = '+';
|
|
|
|
return scnprintf(buf, size, "%u,%llu,%llu,%c;",
|
|
(msg->facility << 3) | msg->level, seq, ts_usec, cont);
|
|
}
|
|
|
|
static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
char *dict, size_t dict_len,
|
|
char *text, size_t text_len)
|
|
{
|
|
char *p = buf, *e = buf + size;
|
|
size_t i;
|
|
|
|
/* escape non-printable characters */
|
|
for (i = 0; i < text_len; i++) {
|
|
unsigned char c = text[i];
|
|
|
|
if (c < ' ' || c >= 127 || c == '\\')
|
|
p += scnprintf(p, e - p, "\\x%02x", c);
|
|
else
|
|
append_char(&p, e, c);
|
|
}
|
|
append_char(&p, e, '\n');
|
|
|
|
if (dict_len) {
|
|
bool line = true;
|
|
|
|
for (i = 0; i < dict_len; i++) {
|
|
unsigned char c = dict[i];
|
|
|
|
if (line) {
|
|
append_char(&p, e, ' ');
|
|
line = false;
|
|
}
|
|
|
|
if (c == '\0') {
|
|
append_char(&p, e, '\n');
|
|
line = true;
|
|
continue;
|
|
}
|
|
|
|
if (c < ' ' || c >= 127 || c == '\\') {
|
|
p += scnprintf(p, e - p, "\\x%02x", c);
|
|
continue;
|
|
}
|
|
|
|
append_char(&p, e, c);
|
|
}
|
|
append_char(&p, e, '\n');
|
|
}
|
|
|
|
return p - buf;
|
|
}
|
|
|
|
/* /dev/kmsg - userspace message inject/listen interface */
|
|
struct devkmsg_user {
|
|
u64 seq;
|
|
u32 idx;
|
|
enum log_flags prev;
|
|
struct mutex lock;
|
|
char buf[CONSOLE_EXT_LOG_MAX];
|
|
};
|
|
|
|
static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
|
|
{
|
|
char *buf, *line;
|
|
int level = default_message_loglevel;
|
|
int facility = 1; /* LOG_USER */
|
|
size_t len = iov_iter_count(from);
|
|
ssize_t ret = len;
|
|
|
|
if (len > LOG_LINE_MAX)
|
|
return -EINVAL;
|
|
buf = kmalloc(len+1, GFP_KERNEL);
|
|
if (buf == NULL)
|
|
return -ENOMEM;
|
|
|
|
buf[len] = '\0';
|
|
if (copy_from_iter(buf, len, from) != len) {
|
|
kfree(buf);
|
|
return -EFAULT;
|
|
}
|
|
|
|
/*
|
|
* Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
|
|
* the decimal value represents 32bit, the lower 3 bit are the log
|
|
* level, the rest are the log facility.
|
|
*
|
|
* If no prefix or no userspace facility is specified, we
|
|
* enforce LOG_USER, to be able to reliably distinguish
|
|
* kernel-generated messages from userspace-injected ones.
|
|
*/
|
|
line = buf;
|
|
if (line[0] == '<') {
|
|
char *endp = NULL;
|
|
unsigned int u;
|
|
|
|
u = simple_strtoul(line + 1, &endp, 10);
|
|
if (endp && endp[0] == '>') {
|
|
level = LOG_LEVEL(u);
|
|
if (LOG_FACILITY(u) != 0)
|
|
facility = LOG_FACILITY(u);
|
|
endp++;
|
|
len -= endp - line;
|
|
line = endp;
|
|
}
|
|
}
|
|
|
|
printk_emit(facility, level, NULL, 0, "%s", line);
|
|
kfree(buf);
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t devkmsg_read(struct file *file, char __user *buf,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
struct printk_log *msg;
|
|
size_t len;
|
|
ssize_t ret;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
|
|
ret = mutex_lock_interruptible(&user->lock);
|
|
if (ret)
|
|
return ret;
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
while (user->seq == log_next_seq) {
|
|
if (file->f_flags & O_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
goto out;
|
|
}
|
|
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
ret = wait_event_interruptible(log_wait,
|
|
user->seq != log_next_seq);
|
|
if (ret)
|
|
goto out;
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
}
|
|
|
|
if (user->seq < log_first_seq) {
|
|
/* our last seen message is gone, return error and reset */
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
ret = -EPIPE;
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
goto out;
|
|
}
|
|
|
|
msg = log_from_idx(user->idx);
|
|
len = msg_print_ext_header(user->buf, sizeof(user->buf),
|
|
msg, user->seq, user->prev);
|
|
len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
|
|
log_dict(msg), msg->dict_len,
|
|
log_text(msg), msg->text_len);
|
|
|
|
user->prev = msg->flags;
|
|
user->idx = log_next(user->idx);
|
|
user->seq++;
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
|
|
if (len > count) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
if (copy_to_user(buf, user->buf, len)) {
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
ret = len;
|
|
out:
|
|
mutex_unlock(&user->lock);
|
|
return ret;
|
|
}
|
|
|
|
static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
loff_t ret = 0;
|
|
|
|
if (!user)
|
|
return -EBADF;
|
|
if (offset)
|
|
return -ESPIPE;
|
|
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
switch (whence) {
|
|
case SEEK_SET:
|
|
/* the first record */
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
break;
|
|
case SEEK_DATA:
|
|
/*
|
|
* The first record after the last SYSLOG_ACTION_CLEAR,
|
|
* like issued by 'dmesg -c'. Reading /dev/kmsg itself
|
|
* changes no global state, and does not clear anything.
|
|
*/
|
|
user->idx = clear_idx;
|
|
user->seq = clear_seq;
|
|
break;
|
|
case SEEK_END:
|
|
/* after the last record */
|
|
user->idx = log_next_idx;
|
|
user->seq = log_next_seq;
|
|
break;
|
|
default:
|
|
ret = -EINVAL;
|
|
}
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
return ret;
|
|
}
|
|
|
|
static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
int ret = 0;
|
|
|
|
if (!user)
|
|
return POLLERR|POLLNVAL;
|
|
|
|
poll_wait(file, &log_wait, wait);
|
|
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
if (user->seq < log_next_seq) {
|
|
/* return error when data has vanished underneath us */
|
|
if (user->seq < log_first_seq)
|
|
ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
|
|
else
|
|
ret = POLLIN|POLLRDNORM;
|
|
}
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int devkmsg_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct devkmsg_user *user;
|
|
int err;
|
|
|
|
/* write-only does not need any file context */
|
|
if ((file->f_flags & O_ACCMODE) == O_WRONLY)
|
|
return 0;
|
|
|
|
err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
|
|
SYSLOG_FROM_READER);
|
|
if (err)
|
|
return err;
|
|
|
|
user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
|
|
if (!user)
|
|
return -ENOMEM;
|
|
|
|
mutex_init(&user->lock);
|
|
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
user->idx = log_first_idx;
|
|
user->seq = log_first_seq;
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
|
|
file->private_data = user;
|
|
return 0;
|
|
}
|
|
|
|
static int devkmsg_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct devkmsg_user *user = file->private_data;
|
|
|
|
if (!user)
|
|
return 0;
|
|
|
|
mutex_destroy(&user->lock);
|
|
kfree(user);
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations kmsg_fops = {
|
|
.open = devkmsg_open,
|
|
.read = devkmsg_read,
|
|
.write_iter = devkmsg_write,
|
|
.llseek = devkmsg_llseek,
|
|
.poll = devkmsg_poll,
|
|
.release = devkmsg_release,
|
|
};
|
|
|
|
#ifdef CONFIG_KEXEC_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_kexec_setup(void)
|
|
{
|
|
VMCOREINFO_SYMBOL(log_buf);
|
|
VMCOREINFO_SYMBOL(log_buf_len);
|
|
VMCOREINFO_SYMBOL(log_first_idx);
|
|
VMCOREINFO_SYMBOL(clear_idx);
|
|
VMCOREINFO_SYMBOL(log_next_idx);
|
|
/*
|
|
* Export struct printk_log size and field offsets. User space tools can
|
|
* parse it and detect any changes to structure down the line.
|
|
*/
|
|
VMCOREINFO_STRUCT_SIZE(printk_log);
|
|
VMCOREINFO_OFFSET(printk_log, ts_nsec);
|
|
VMCOREINFO_OFFSET(printk_log, len);
|
|
VMCOREINFO_OFFSET(printk_log, text_len);
|
|
VMCOREINFO_OFFSET(printk_log, dict_len);
|
|
}
|
|
#endif
|
|
|
|
/* requested log_buf_len from kernel cmdline */
|
|
static unsigned long __initdata new_log_buf_len;
|
|
|
|
/* we practice scaling the ring buffer by powers of 2 */
|
|
static void __init log_buf_len_update(unsigned size)
|
|
{
|
|
if (size)
|
|
size = roundup_pow_of_two(size);
|
|
if (size > log_buf_len)
|
|
new_log_buf_len = size;
|
|
}
|
|
|
|
/* save requested log_buf_len since it's too early to process it */
|
|
static int __init log_buf_len_setup(char *str)
|
|
{
|
|
unsigned size = memparse(str, &str);
|
|
|
|
log_buf_len_update(size);
|
|
|
|
return 0;
|
|
}
|
|
early_param("log_buf_len", log_buf_len_setup);
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
|
|
|
|
static void __init log_buf_add_cpu(void)
|
|
{
|
|
unsigned int cpu_extra;
|
|
|
|
/*
|
|
* archs should set up cpu_possible_bits properly with
|
|
* set_cpu_possible() after setup_arch() but just in
|
|
* case lets ensure this is valid.
|
|
*/
|
|
if (num_possible_cpus() == 1)
|
|
return;
|
|
|
|
cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
|
|
|
|
/* by default this will only continue through for large > 64 CPUs */
|
|
if (cpu_extra <= __LOG_BUF_LEN / 2)
|
|
return;
|
|
|
|
pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
|
|
__LOG_CPU_MAX_BUF_LEN);
|
|
pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
|
|
cpu_extra);
|
|
pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN);
|
|
|
|
log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
|
|
}
|
|
#else /* !CONFIG_SMP */
|
|
static inline void log_buf_add_cpu(void) {}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
void __init setup_log_buf(int early)
|
|
{
|
|
unsigned long flags;
|
|
char *new_log_buf;
|
|
int free;
|
|
|
|
if (log_buf != __log_buf)
|
|
return;
|
|
|
|
if (!early && !new_log_buf_len)
|
|
log_buf_add_cpu();
|
|
|
|
if (!new_log_buf_len)
|
|
return;
|
|
|
|
if (early) {
|
|
new_log_buf =
|
|
memblock_virt_alloc(new_log_buf_len, LOG_ALIGN);
|
|
} else {
|
|
new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len,
|
|
LOG_ALIGN);
|
|
}
|
|
|
|
if (unlikely(!new_log_buf)) {
|
|
pr_err("log_buf_len: %ld bytes not available\n",
|
|
new_log_buf_len);
|
|
return;
|
|
}
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
log_buf_len = new_log_buf_len;
|
|
log_buf = new_log_buf;
|
|
new_log_buf_len = 0;
|
|
free = __LOG_BUF_LEN - log_next_idx;
|
|
memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
|
|
pr_info("log_buf_len: %d bytes\n", log_buf_len);
|
|
pr_info("early log buf free: %d(%d%%)\n",
|
|
free, (free * 100) / __LOG_BUF_LEN);
|
|
}
|
|
|
|
static bool __read_mostly ignore_loglevel;
|
|
|
|
static int __init ignore_loglevel_setup(char *str)
|
|
{
|
|
ignore_loglevel = true;
|
|
pr_info("debug: ignoring loglevel setting.\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("ignore_loglevel", ignore_loglevel_setup);
|
|
module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(ignore_loglevel,
|
|
"ignore loglevel setting (prints all kernel messages to the console)");
|
|
|
|
#ifdef CONFIG_BOOT_PRINTK_DELAY
|
|
|
|
static int boot_delay; /* msecs delay after each printk during bootup */
|
|
static unsigned long long loops_per_msec; /* based on boot_delay */
|
|
|
|
static int __init boot_delay_setup(char *str)
|
|
{
|
|
unsigned long lpj;
|
|
|
|
lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
|
|
loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
|
|
|
|
get_option(&str, &boot_delay);
|
|
if (boot_delay > 10 * 1000)
|
|
boot_delay = 0;
|
|
|
|
pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
|
|
"HZ: %d, loops_per_msec: %llu\n",
|
|
boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
|
|
return 0;
|
|
}
|
|
early_param("boot_delay", boot_delay_setup);
|
|
|
|
static void boot_delay_msec(int level)
|
|
{
|
|
unsigned long long k;
|
|
unsigned long timeout;
|
|
|
|
if ((boot_delay == 0 || system_state != SYSTEM_BOOTING)
|
|
|| (level >= console_loglevel && !ignore_loglevel)) {
|
|
return;
|
|
}
|
|
|
|
k = (unsigned long long)loops_per_msec * boot_delay;
|
|
|
|
timeout = jiffies + msecs_to_jiffies(boot_delay);
|
|
while (k) {
|
|
k--;
|
|
cpu_relax();
|
|
/*
|
|
* use (volatile) jiffies to prevent
|
|
* compiler reduction; loop termination via jiffies
|
|
* is secondary and may or may not happen.
|
|
*/
|
|
if (time_after(jiffies, timeout))
|
|
break;
|
|
touch_nmi_watchdog();
|
|
}
|
|
}
|
|
#else
|
|
static inline void boot_delay_msec(int level)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
|
|
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
|
|
|
|
static size_t print_time(u64 ts, char *buf)
|
|
{
|
|
unsigned long rem_nsec;
|
|
|
|
if (!printk_time)
|
|
return 0;
|
|
|
|
rem_nsec = do_div(ts, 1000000000);
|
|
|
|
if (!buf)
|
|
return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
|
|
|
|
return sprintf(buf, "[%5lu.%06lu] ",
|
|
(unsigned long)ts, rem_nsec / 1000);
|
|
}
|
|
|
|
static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
|
|
{
|
|
size_t len = 0;
|
|
unsigned int prefix = (msg->facility << 3) | msg->level;
|
|
|
|
if (syslog) {
|
|
if (buf) {
|
|
len += sprintf(buf, "<%u>", prefix);
|
|
} else {
|
|
len += 3;
|
|
if (prefix > 999)
|
|
len += 3;
|
|
else if (prefix > 99)
|
|
len += 2;
|
|
else if (prefix > 9)
|
|
len++;
|
|
}
|
|
}
|
|
|
|
len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
|
|
return len;
|
|
}
|
|
|
|
static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
|
|
bool syslog, char *buf, size_t size)
|
|
{
|
|
const char *text = log_text(msg);
|
|
size_t text_size = msg->text_len;
|
|
bool prefix = true;
|
|
bool newline = true;
|
|
size_t len = 0;
|
|
|
|
if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
|
|
prefix = false;
|
|
|
|
if (msg->flags & LOG_CONT) {
|
|
if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
|
|
prefix = false;
|
|
|
|
if (!(msg->flags & LOG_NEWLINE))
|
|
newline = false;
|
|
}
|
|
|
|
do {
|
|
const char *next = memchr(text, '\n', text_size);
|
|
size_t text_len;
|
|
|
|
if (next) {
|
|
text_len = next - text;
|
|
next++;
|
|
text_size -= next - text;
|
|
} else {
|
|
text_len = text_size;
|
|
}
|
|
|
|
if (buf) {
|
|
if (print_prefix(msg, syslog, NULL) +
|
|
text_len + 1 >= size - len)
|
|
break;
|
|
|
|
if (prefix)
|
|
len += print_prefix(msg, syslog, buf + len);
|
|
memcpy(buf + len, text, text_len);
|
|
len += text_len;
|
|
if (next || newline)
|
|
buf[len++] = '\n';
|
|
} else {
|
|
/* SYSLOG_ACTION_* buffer size only calculation */
|
|
if (prefix)
|
|
len += print_prefix(msg, syslog, NULL);
|
|
len += text_len;
|
|
if (next || newline)
|
|
len++;
|
|
}
|
|
|
|
prefix = true;
|
|
text = next;
|
|
} while (text);
|
|
|
|
return len;
|
|
}
|
|
|
|
static int syslog_print(char __user *buf, int size)
|
|
{
|
|
char *text;
|
|
struct printk_log *msg;
|
|
int len = 0;
|
|
|
|
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
while (size > 0) {
|
|
size_t n;
|
|
size_t skip;
|
|
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
if (syslog_seq < log_first_seq) {
|
|
/* messages are gone, move to first one */
|
|
syslog_seq = log_first_seq;
|
|
syslog_idx = log_first_idx;
|
|
syslog_prev = 0;
|
|
syslog_partial = 0;
|
|
}
|
|
if (syslog_seq == log_next_seq) {
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
break;
|
|
}
|
|
|
|
skip = syslog_partial;
|
|
msg = log_from_idx(syslog_idx);
|
|
n = msg_print_text(msg, syslog_prev, true, text,
|
|
LOG_LINE_MAX + PREFIX_MAX);
|
|
if (n - syslog_partial <= size) {
|
|
/* message fits into buffer, move forward */
|
|
syslog_idx = log_next(syslog_idx);
|
|
syslog_seq++;
|
|
syslog_prev = msg->flags;
|
|
n -= syslog_partial;
|
|
syslog_partial = 0;
|
|
} else if (!len){
|
|
/* partial read(), remember position */
|
|
n = size;
|
|
syslog_partial += n;
|
|
} else
|
|
n = 0;
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
|
|
if (!n)
|
|
break;
|
|
|
|
if (copy_to_user(buf, text + skip, n)) {
|
|
if (!len)
|
|
len = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
len += n;
|
|
size -= n;
|
|
buf += n;
|
|
}
|
|
|
|
kfree(text);
|
|
return len;
|
|
}
|
|
|
|
static int syslog_print_all(char __user *buf, int size, bool clear)
|
|
{
|
|
char *text;
|
|
int len = 0;
|
|
|
|
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
|
|
if (!text)
|
|
return -ENOMEM;
|
|
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
if (buf) {
|
|
u64 next_seq;
|
|
u64 seq;
|
|
u32 idx;
|
|
enum log_flags prev;
|
|
|
|
/*
|
|
* Find first record that fits, including all following records,
|
|
* into the user-provided buffer for this dump.
|
|
*/
|
|
seq = clear_seq;
|
|
idx = clear_idx;
|
|
prev = 0;
|
|
while (seq < log_next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
len += msg_print_text(msg, prev, true, NULL, 0);
|
|
prev = msg->flags;
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* move first record forward until length fits into the buffer */
|
|
seq = clear_seq;
|
|
idx = clear_idx;
|
|
prev = 0;
|
|
while (len > size && seq < log_next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
len -= msg_print_text(msg, prev, true, NULL, 0);
|
|
prev = msg->flags;
|
|
idx = log_next(idx);
|
|
seq++;
|
|
}
|
|
|
|
/* last message fitting into this dump */
|
|
next_seq = log_next_seq;
|
|
|
|
len = 0;
|
|
while (len >= 0 && seq < next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
int textlen;
|
|
|
|
textlen = msg_print_text(msg, prev, true, text,
|
|
LOG_LINE_MAX + PREFIX_MAX);
|
|
if (textlen < 0) {
|
|
len = textlen;
|
|
break;
|
|
}
|
|
idx = log_next(idx);
|
|
seq++;
|
|
prev = msg->flags;
|
|
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
if (copy_to_user(buf + len, text, textlen))
|
|
len = -EFAULT;
|
|
else
|
|
len += textlen;
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
|
|
if (seq < log_first_seq) {
|
|
/* messages are gone, move to next one */
|
|
seq = log_first_seq;
|
|
idx = log_first_idx;
|
|
prev = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (clear) {
|
|
clear_seq = log_next_seq;
|
|
clear_idx = log_next_idx;
|
|
}
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
|
|
kfree(text);
|
|
return len;
|
|
}
|
|
|
|
int do_syslog(int type, char __user *buf, int len, int source)
|
|
{
|
|
bool clear = false;
|
|
static int saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
int error;
|
|
|
|
error = check_syslog_permissions(type, source);
|
|
if (error)
|
|
goto out;
|
|
|
|
switch (type) {
|
|
case SYSLOG_ACTION_CLOSE: /* Close log */
|
|
break;
|
|
case SYSLOG_ACTION_OPEN: /* Open log */
|
|
break;
|
|
case SYSLOG_ACTION_READ: /* Read from log */
|
|
error = -EINVAL;
|
|
if (!buf || len < 0)
|
|
goto out;
|
|
error = 0;
|
|
if (!len)
|
|
goto out;
|
|
if (!access_ok(VERIFY_WRITE, buf, len)) {
|
|
error = -EFAULT;
|
|
goto out;
|
|
}
|
|
error = wait_event_interruptible(log_wait,
|
|
syslog_seq != log_next_seq);
|
|
if (error)
|
|
goto out;
|
|
error = syslog_print(buf, len);
|
|
break;
|
|
/* Read/clear last kernel messages */
|
|
case SYSLOG_ACTION_READ_CLEAR:
|
|
clear = true;
|
|
/* FALL THRU */
|
|
/* Read last kernel messages */
|
|
case SYSLOG_ACTION_READ_ALL:
|
|
error = -EINVAL;
|
|
if (!buf || len < 0)
|
|
goto out;
|
|
error = 0;
|
|
if (!len)
|
|
goto out;
|
|
if (!access_ok(VERIFY_WRITE, buf, len)) {
|
|
error = -EFAULT;
|
|
goto out;
|
|
}
|
|
error = syslog_print_all(buf, len, clear);
|
|
break;
|
|
/* Clear ring buffer */
|
|
case SYSLOG_ACTION_CLEAR:
|
|
syslog_print_all(NULL, 0, true);
|
|
break;
|
|
/* Disable logging to console */
|
|
case SYSLOG_ACTION_CONSOLE_OFF:
|
|
if (saved_console_loglevel == LOGLEVEL_DEFAULT)
|
|
saved_console_loglevel = console_loglevel;
|
|
console_loglevel = minimum_console_loglevel;
|
|
break;
|
|
/* Enable logging to console */
|
|
case SYSLOG_ACTION_CONSOLE_ON:
|
|
if (saved_console_loglevel != LOGLEVEL_DEFAULT) {
|
|
console_loglevel = saved_console_loglevel;
|
|
saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
}
|
|
break;
|
|
/* Set level of messages printed to console */
|
|
case SYSLOG_ACTION_CONSOLE_LEVEL:
|
|
error = -EINVAL;
|
|
if (len < 1 || len > 8)
|
|
goto out;
|
|
if (len < minimum_console_loglevel)
|
|
len = minimum_console_loglevel;
|
|
console_loglevel = len;
|
|
/* Implicitly re-enable logging to console */
|
|
saved_console_loglevel = LOGLEVEL_DEFAULT;
|
|
error = 0;
|
|
break;
|
|
/* Number of chars in the log buffer */
|
|
case SYSLOG_ACTION_SIZE_UNREAD:
|
|
raw_spin_lock_irq(&logbuf_lock);
|
|
if (syslog_seq < log_first_seq) {
|
|
/* messages are gone, move to first one */
|
|
syslog_seq = log_first_seq;
|
|
syslog_idx = log_first_idx;
|
|
syslog_prev = 0;
|
|
syslog_partial = 0;
|
|
}
|
|
if (source == SYSLOG_FROM_PROC) {
|
|
/*
|
|
* Short-cut for poll(/"proc/kmsg") which simply checks
|
|
* for pending data, not the size; return the count of
|
|
* records, not the length.
|
|
*/
|
|
error = log_next_seq - syslog_seq;
|
|
} else {
|
|
u64 seq = syslog_seq;
|
|
u32 idx = syslog_idx;
|
|
enum log_flags prev = syslog_prev;
|
|
|
|
error = 0;
|
|
while (seq < log_next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
error += msg_print_text(msg, prev, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
prev = msg->flags;
|
|
}
|
|
error -= syslog_partial;
|
|
}
|
|
raw_spin_unlock_irq(&logbuf_lock);
|
|
break;
|
|
/* Size of the log buffer */
|
|
case SYSLOG_ACTION_SIZE_BUFFER:
|
|
error = log_buf_len;
|
|
break;
|
|
default:
|
|
error = -EINVAL;
|
|
break;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
|
|
{
|
|
return do_syslog(type, buf, len, SYSLOG_FROM_READER);
|
|
}
|
|
|
|
/*
|
|
* Call the console drivers, asking them to write out
|
|
* log_buf[start] to log_buf[end - 1].
|
|
* The console_lock must be held.
|
|
*/
|
|
static void call_console_drivers(int level,
|
|
const char *ext_text, size_t ext_len,
|
|
const char *text, size_t len)
|
|
{
|
|
struct console *con;
|
|
|
|
trace_console(text, len);
|
|
|
|
if (level >= console_loglevel && !ignore_loglevel)
|
|
return;
|
|
if (!console_drivers)
|
|
return;
|
|
|
|
for_each_console(con) {
|
|
if (exclusive_console && con != exclusive_console)
|
|
continue;
|
|
if (!(con->flags & CON_ENABLED))
|
|
continue;
|
|
if (!con->write)
|
|
continue;
|
|
if (!cpu_online(smp_processor_id()) &&
|
|
!(con->flags & CON_ANYTIME))
|
|
continue;
|
|
if (con->flags & CON_EXTENDED)
|
|
con->write(con, ext_text, ext_len);
|
|
else
|
|
con->write(con, text, len);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Zap console related locks when oopsing.
|
|
* To leave time for slow consoles to print a full oops,
|
|
* only zap at most once every 30 seconds.
|
|
*/
|
|
static void zap_locks(void)
|
|
{
|
|
static unsigned long oops_timestamp;
|
|
|
|
if (time_after_eq(jiffies, oops_timestamp) &&
|
|
!time_after(jiffies, oops_timestamp + 30 * HZ))
|
|
return;
|
|
|
|
oops_timestamp = jiffies;
|
|
|
|
debug_locks_off();
|
|
/* If a crash is occurring, make sure we can't deadlock */
|
|
raw_spin_lock_init(&logbuf_lock);
|
|
/* And make sure that we print immediately */
|
|
sema_init(&console_sem, 1);
|
|
}
|
|
|
|
int printk_delay_msec __read_mostly;
|
|
|
|
static inline void printk_delay(void)
|
|
{
|
|
if (unlikely(printk_delay_msec)) {
|
|
int m = printk_delay_msec;
|
|
|
|
while (m--) {
|
|
mdelay(1);
|
|
touch_nmi_watchdog();
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Continuation lines are buffered, and not committed to the record buffer
|
|
* until the line is complete, or a race forces it. The line fragments
|
|
* though, are printed immediately to the consoles to ensure everything has
|
|
* reached the console in case of a kernel crash.
|
|
*/
|
|
static struct cont {
|
|
char buf[LOG_LINE_MAX];
|
|
size_t len; /* length == 0 means unused buffer */
|
|
size_t cons; /* bytes written to console */
|
|
struct task_struct *owner; /* task of first print*/
|
|
u64 ts_nsec; /* time of first print */
|
|
u8 level; /* log level of first message */
|
|
u8 facility; /* log facility of first message */
|
|
enum log_flags flags; /* prefix, newline flags */
|
|
bool flushed:1; /* buffer sealed and committed */
|
|
} cont;
|
|
|
|
static void cont_flush(enum log_flags flags)
|
|
{
|
|
if (cont.flushed)
|
|
return;
|
|
if (cont.len == 0)
|
|
return;
|
|
|
|
if (cont.cons) {
|
|
/*
|
|
* If a fragment of this line was directly flushed to the
|
|
* console; wait for the console to pick up the rest of the
|
|
* line. LOG_NOCONS suppresses a duplicated output.
|
|
*/
|
|
log_store(cont.facility, cont.level, flags | LOG_NOCONS,
|
|
cont.ts_nsec, NULL, 0, cont.buf, cont.len);
|
|
cont.flags = flags;
|
|
cont.flushed = true;
|
|
} else {
|
|
/*
|
|
* If no fragment of this line ever reached the console,
|
|
* just submit it to the store and free the buffer.
|
|
*/
|
|
log_store(cont.facility, cont.level, flags, 0,
|
|
NULL, 0, cont.buf, cont.len);
|
|
cont.len = 0;
|
|
}
|
|
}
|
|
|
|
static bool cont_add(int facility, int level, const char *text, size_t len)
|
|
{
|
|
if (cont.len && cont.flushed)
|
|
return false;
|
|
|
|
/*
|
|
* If ext consoles are present, flush and skip in-kernel
|
|
* continuation. See nr_ext_console_drivers definition. Also, if
|
|
* the line gets too long, split it up in separate records.
|
|
*/
|
|
if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) {
|
|
cont_flush(LOG_CONT);
|
|
return false;
|
|
}
|
|
|
|
if (!cont.len) {
|
|
cont.facility = facility;
|
|
cont.level = level;
|
|
cont.owner = current;
|
|
cont.ts_nsec = local_clock();
|
|
cont.flags = 0;
|
|
cont.cons = 0;
|
|
cont.flushed = false;
|
|
}
|
|
|
|
memcpy(cont.buf + cont.len, text, len);
|
|
cont.len += len;
|
|
|
|
if (cont.len > (sizeof(cont.buf) * 80) / 100)
|
|
cont_flush(LOG_CONT);
|
|
|
|
return true;
|
|
}
|
|
|
|
static size_t cont_print_text(char *text, size_t size)
|
|
{
|
|
size_t textlen = 0;
|
|
size_t len;
|
|
|
|
if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
|
|
textlen += print_time(cont.ts_nsec, text);
|
|
size -= textlen;
|
|
}
|
|
|
|
len = cont.len - cont.cons;
|
|
if (len > 0) {
|
|
if (len+1 > size)
|
|
len = size-1;
|
|
memcpy(text + textlen, cont.buf + cont.cons, len);
|
|
textlen += len;
|
|
cont.cons = cont.len;
|
|
}
|
|
|
|
if (cont.flushed) {
|
|
if (cont.flags & LOG_NEWLINE)
|
|
text[textlen++] = '\n';
|
|
/* got everything, release buffer */
|
|
cont.len = 0;
|
|
}
|
|
return textlen;
|
|
}
|
|
|
|
asmlinkage int vprintk_emit(int facility, int level,
|
|
const char *dict, size_t dictlen,
|
|
const char *fmt, va_list args)
|
|
{
|
|
static bool recursion_bug;
|
|
static char textbuf[LOG_LINE_MAX];
|
|
char *text = textbuf;
|
|
size_t text_len = 0;
|
|
enum log_flags lflags = 0;
|
|
unsigned long flags;
|
|
int this_cpu;
|
|
int printed_len = 0;
|
|
bool in_sched = false;
|
|
/* cpu currently holding logbuf_lock in this function */
|
|
static unsigned int logbuf_cpu = UINT_MAX;
|
|
|
|
if (level == LOGLEVEL_SCHED) {
|
|
level = LOGLEVEL_DEFAULT;
|
|
in_sched = true;
|
|
}
|
|
|
|
boot_delay_msec(level);
|
|
printk_delay();
|
|
|
|
local_irq_save(flags);
|
|
this_cpu = smp_processor_id();
|
|
|
|
/*
|
|
* Ouch, printk recursed into itself!
|
|
*/
|
|
if (unlikely(logbuf_cpu == this_cpu)) {
|
|
/*
|
|
* If a crash is occurring during printk() on this CPU,
|
|
* then try to get the crash message out but make sure
|
|
* we can't deadlock. Otherwise just return to avoid the
|
|
* recursion and return - but flag the recursion so that
|
|
* it can be printed at the next appropriate moment:
|
|
*/
|
|
if (!oops_in_progress && !lockdep_recursing(current)) {
|
|
recursion_bug = true;
|
|
local_irq_restore(flags);
|
|
return 0;
|
|
}
|
|
zap_locks();
|
|
}
|
|
|
|
lockdep_off();
|
|
/* This stops the holder of console_sem just where we want him */
|
|
raw_spin_lock(&logbuf_lock);
|
|
logbuf_cpu = this_cpu;
|
|
|
|
if (unlikely(recursion_bug)) {
|
|
static const char recursion_msg[] =
|
|
"BUG: recent printk recursion!";
|
|
|
|
recursion_bug = false;
|
|
/* emit KERN_CRIT message */
|
|
printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
|
|
NULL, 0, recursion_msg,
|
|
strlen(recursion_msg));
|
|
}
|
|
|
|
/*
|
|
* The printf needs to come first; we need the syslog
|
|
* prefix which might be passed-in as a parameter.
|
|
*/
|
|
text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
|
|
|
|
/* mark and strip a trailing newline */
|
|
if (text_len && text[text_len-1] == '\n') {
|
|
text_len--;
|
|
lflags |= LOG_NEWLINE;
|
|
}
|
|
|
|
/* strip kernel syslog prefix and extract log level or control flags */
|
|
if (facility == 0) {
|
|
int kern_level = printk_get_level(text);
|
|
|
|
if (kern_level) {
|
|
const char *end_of_header = printk_skip_level(text);
|
|
switch (kern_level) {
|
|
case '0' ... '7':
|
|
if (level == LOGLEVEL_DEFAULT)
|
|
level = kern_level - '0';
|
|
/* fallthrough */
|
|
case 'd': /* KERN_DEFAULT */
|
|
lflags |= LOG_PREFIX;
|
|
}
|
|
/*
|
|
* No need to check length here because vscnprintf
|
|
* put '\0' at the end of the string. Only valid and
|
|
* newly printed level is detected.
|
|
*/
|
|
text_len -= end_of_header - text;
|
|
text = (char *)end_of_header;
|
|
}
|
|
}
|
|
|
|
if (level == LOGLEVEL_DEFAULT)
|
|
level = default_message_loglevel;
|
|
|
|
if (dict)
|
|
lflags |= LOG_PREFIX|LOG_NEWLINE;
|
|
|
|
if (!(lflags & LOG_NEWLINE)) {
|
|
/*
|
|
* Flush the conflicting buffer. An earlier newline was missing,
|
|
* or another task also prints continuation lines.
|
|
*/
|
|
if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
|
|
cont_flush(LOG_NEWLINE);
|
|
|
|
/* buffer line if possible, otherwise store it right away */
|
|
if (cont_add(facility, level, text, text_len))
|
|
printed_len += text_len;
|
|
else
|
|
printed_len += log_store(facility, level,
|
|
lflags | LOG_CONT, 0,
|
|
dict, dictlen, text, text_len);
|
|
} else {
|
|
bool stored = false;
|
|
|
|
/*
|
|
* If an earlier newline was missing and it was the same task,
|
|
* either merge it with the current buffer and flush, or if
|
|
* there was a race with interrupts (prefix == true) then just
|
|
* flush it out and store this line separately.
|
|
* If the preceding printk was from a different task and missed
|
|
* a newline, flush and append the newline.
|
|
*/
|
|
if (cont.len) {
|
|
if (cont.owner == current && !(lflags & LOG_PREFIX))
|
|
stored = cont_add(facility, level, text,
|
|
text_len);
|
|
cont_flush(LOG_NEWLINE);
|
|
}
|
|
|
|
if (stored)
|
|
printed_len += text_len;
|
|
else
|
|
printed_len += log_store(facility, level, lflags, 0,
|
|
dict, dictlen, text, text_len);
|
|
}
|
|
|
|
logbuf_cpu = UINT_MAX;
|
|
raw_spin_unlock(&logbuf_lock);
|
|
lockdep_on();
|
|
local_irq_restore(flags);
|
|
|
|
/* If called from the scheduler, we can not call up(). */
|
|
if (!in_sched) {
|
|
lockdep_off();
|
|
/*
|
|
* 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())
|
|
console_unlock();
|
|
lockdep_on();
|
|
}
|
|
|
|
return printed_len;
|
|
}
|
|
EXPORT_SYMBOL(vprintk_emit);
|
|
|
|
asmlinkage int vprintk(const char *fmt, va_list args)
|
|
{
|
|
return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
|
|
}
|
|
EXPORT_SYMBOL(vprintk);
|
|
|
|
asmlinkage int printk_emit(int facility, int level,
|
|
const char *dict, size_t dictlen,
|
|
const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(printk_emit);
|
|
|
|
int vprintk_default(const char *fmt, va_list args)
|
|
{
|
|
int r;
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
if (unlikely(kdb_trap_printk)) {
|
|
r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
|
|
return r;
|
|
}
|
|
#endif
|
|
r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vprintk_default);
|
|
|
|
/*
|
|
* This allows printk to be diverted to another function per cpu.
|
|
* This is useful for calling printk functions from within NMI
|
|
* without worrying about race conditions that can lock up the
|
|
* box.
|
|
*/
|
|
DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
|
|
|
|
/**
|
|
* printk - print a kernel message
|
|
* @fmt: format string
|
|
*
|
|
* This is printk(). It can be called from any context. We want it to work.
|
|
*
|
|
* We try to grab the console_lock. If we succeed, it's easy - we log the
|
|
* output and call the console drivers. If we fail to get the semaphore, we
|
|
* place the output into the log buffer and return. The current holder of
|
|
* the console_sem will notice the new output in console_unlock(); and will
|
|
* send it to the consoles before releasing the lock.
|
|
*
|
|
* One effect of this deferred printing is that code which calls printk() and
|
|
* then changes console_loglevel may break. This is because console_loglevel
|
|
* is inspected when the actual printing occurs.
|
|
*
|
|
* See also:
|
|
* printf(3)
|
|
*
|
|
* See the vsnprintf() documentation for format string extensions over C99.
|
|
*/
|
|
asmlinkage __visible int printk(const char *fmt, ...)
|
|
{
|
|
printk_func_t vprintk_func;
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
|
|
/*
|
|
* If a caller overrides the per_cpu printk_func, then it needs
|
|
* to disable preemption when calling printk(). Otherwise
|
|
* the printk_func should be set to the default. No need to
|
|
* disable preemption here.
|
|
*/
|
|
vprintk_func = this_cpu_read(printk_func);
|
|
r = vprintk_func(fmt, args);
|
|
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(printk);
|
|
|
|
#else /* CONFIG_PRINTK */
|
|
|
|
#define LOG_LINE_MAX 0
|
|
#define PREFIX_MAX 0
|
|
|
|
static u64 syslog_seq;
|
|
static u32 syslog_idx;
|
|
static u64 console_seq;
|
|
static u32 console_idx;
|
|
static enum log_flags syslog_prev;
|
|
static u64 log_first_seq;
|
|
static u32 log_first_idx;
|
|
static u64 log_next_seq;
|
|
static enum log_flags console_prev;
|
|
static struct cont {
|
|
size_t len;
|
|
size_t cons;
|
|
u8 level;
|
|
bool flushed:1;
|
|
} cont;
|
|
static char *log_text(const struct printk_log *msg) { return NULL; }
|
|
static char *log_dict(const struct printk_log *msg) { return NULL; }
|
|
static struct printk_log *log_from_idx(u32 idx) { return NULL; }
|
|
static u32 log_next(u32 idx) { return 0; }
|
|
static ssize_t msg_print_ext_header(char *buf, size_t size,
|
|
struct printk_log *msg, u64 seq,
|
|
enum log_flags prev_flags) { return 0; }
|
|
static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
char *dict, size_t dict_len,
|
|
char *text, size_t text_len) { return 0; }
|
|
static void call_console_drivers(int level,
|
|
const char *ext_text, size_t ext_len,
|
|
const char *text, size_t len) {}
|
|
static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
|
|
bool syslog, char *buf, size_t size) { return 0; }
|
|
static size_t cont_print_text(char *text, size_t size) { return 0; }
|
|
|
|
/* Still needs to be defined for users */
|
|
DEFINE_PER_CPU(printk_func_t, printk_func);
|
|
|
|
#endif /* CONFIG_PRINTK */
|
|
|
|
#ifdef CONFIG_EARLY_PRINTK
|
|
struct console *early_console;
|
|
|
|
asmlinkage __visible void early_printk(const char *fmt, ...)
|
|
{
|
|
va_list ap;
|
|
char buf[512];
|
|
int n;
|
|
|
|
if (!early_console)
|
|
return;
|
|
|
|
va_start(ap, fmt);
|
|
n = vscnprintf(buf, sizeof(buf), fmt, ap);
|
|
va_end(ap);
|
|
|
|
early_console->write(early_console, buf, n);
|
|
}
|
|
#endif
|
|
|
|
static int __add_preferred_console(char *name, int idx, char *options,
|
|
char *brl_options)
|
|
{
|
|
struct console_cmdline *c;
|
|
int i;
|
|
|
|
/*
|
|
* See if this tty is not yet registered, and
|
|
* if we have a slot free.
|
|
*/
|
|
for (i = 0, c = console_cmdline;
|
|
i < MAX_CMDLINECONSOLES && c->name[0];
|
|
i++, c++) {
|
|
if (strcmp(c->name, name) == 0 && c->index == idx) {
|
|
if (!brl_options)
|
|
selected_console = i;
|
|
return 0;
|
|
}
|
|
}
|
|
if (i == MAX_CMDLINECONSOLES)
|
|
return -E2BIG;
|
|
if (!brl_options)
|
|
selected_console = i;
|
|
strlcpy(c->name, name, sizeof(c->name));
|
|
c->options = options;
|
|
braille_set_options(c, brl_options);
|
|
|
|
c->index = idx;
|
|
return 0;
|
|
}
|
|
/*
|
|
* Set up a console. Called via do_early_param() in init/main.c
|
|
* for each "console=" parameter in the boot command line.
|
|
*/
|
|
static int __init console_setup(char *str)
|
|
{
|
|
char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
|
|
char *s, *options, *brl_options = NULL;
|
|
int idx;
|
|
|
|
if (_braille_console_setup(&str, &brl_options))
|
|
return 1;
|
|
|
|
/*
|
|
* Decode str into name, index, options.
|
|
*/
|
|
if (str[0] >= '0' && str[0] <= '9') {
|
|
strcpy(buf, "ttyS");
|
|
strncpy(buf + 4, str, sizeof(buf) - 5);
|
|
} else {
|
|
strncpy(buf, str, sizeof(buf) - 1);
|
|
}
|
|
buf[sizeof(buf) - 1] = 0;
|
|
options = strchr(str, ',');
|
|
if (options)
|
|
*(options++) = 0;
|
|
#ifdef __sparc__
|
|
if (!strcmp(str, "ttya"))
|
|
strcpy(buf, "ttyS0");
|
|
if (!strcmp(str, "ttyb"))
|
|
strcpy(buf, "ttyS1");
|
|
#endif
|
|
for (s = buf; *s; s++)
|
|
if (isdigit(*s) || *s == ',')
|
|
break;
|
|
idx = simple_strtoul(s, NULL, 10);
|
|
*s = 0;
|
|
|
|
__add_preferred_console(buf, idx, options, brl_options);
|
|
console_set_on_cmdline = 1;
|
|
return 1;
|
|
}
|
|
__setup("console=", console_setup);
|
|
|
|
/**
|
|
* add_preferred_console - add a device to the list of preferred consoles.
|
|
* @name: device name
|
|
* @idx: device index
|
|
* @options: options for this console
|
|
*
|
|
* The last preferred console added will be used for kernel messages
|
|
* and stdin/out/err for init. Normally this is used by console_setup
|
|
* above to handle user-supplied console arguments; however it can also
|
|
* be used by arch-specific code either to override the user or more
|
|
* commonly to provide a default console (ie from PROM variables) when
|
|
* the user has not supplied one.
|
|
*/
|
|
int add_preferred_console(char *name, int idx, char *options)
|
|
{
|
|
return __add_preferred_console(name, idx, options, NULL);
|
|
}
|
|
|
|
bool console_suspend_enabled = true;
|
|
EXPORT_SYMBOL(console_suspend_enabled);
|
|
|
|
static int __init console_suspend_disable(char *str)
|
|
{
|
|
console_suspend_enabled = false;
|
|
return 1;
|
|
}
|
|
__setup("no_console_suspend", console_suspend_disable);
|
|
module_param_named(console_suspend, console_suspend_enabled,
|
|
bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
|
|
" and hibernate operations");
|
|
|
|
/**
|
|
* suspend_console - suspend the console subsystem
|
|
*
|
|
* This disables printk() while we go into suspend states
|
|
*/
|
|
void suspend_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
printk("Suspending console(s) (use no_console_suspend to debug)\n");
|
|
console_lock();
|
|
console_suspended = 1;
|
|
up_console_sem();
|
|
}
|
|
|
|
void resume_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
down_console_sem();
|
|
console_suspended = 0;
|
|
console_unlock();
|
|
}
|
|
|
|
/**
|
|
* console_cpu_notify - print deferred console messages after CPU hotplug
|
|
* @self: notifier struct
|
|
* @action: CPU hotplug event
|
|
* @hcpu: unused
|
|
*
|
|
* If printk() is called from a CPU that is not online yet, the messages
|
|
* will be spooled but will not show up on the console. This function is
|
|
* called when a new CPU comes online (or fails to come up), and ensures
|
|
* that any such output gets printed.
|
|
*/
|
|
static int console_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
switch (action) {
|
|
case CPU_ONLINE:
|
|
case CPU_DEAD:
|
|
case CPU_DOWN_FAILED:
|
|
case CPU_UP_CANCELED:
|
|
console_lock();
|
|
console_unlock();
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
/**
|
|
* console_lock - lock the console system for exclusive use.
|
|
*
|
|
* Acquires a lock which guarantees that the caller has
|
|
* exclusive access to the console system and the console_drivers list.
|
|
*
|
|
* Can sleep, returns nothing.
|
|
*/
|
|
void console_lock(void)
|
|
{
|
|
might_sleep();
|
|
|
|
down_console_sem();
|
|
if (console_suspended)
|
|
return;
|
|
console_locked = 1;
|
|
console_may_schedule = 1;
|
|
}
|
|
EXPORT_SYMBOL(console_lock);
|
|
|
|
/**
|
|
* console_trylock - try to lock the console system for exclusive use.
|
|
*
|
|
* Try to acquire a lock which guarantees that the caller has exclusive
|
|
* access to the console system and the console_drivers list.
|
|
*
|
|
* returns 1 on success, and 0 on failure to acquire the lock.
|
|
*/
|
|
int console_trylock(void)
|
|
{
|
|
if (down_trylock_console_sem())
|
|
return 0;
|
|
if (console_suspended) {
|
|
up_console_sem();
|
|
return 0;
|
|
}
|
|
console_locked = 1;
|
|
/*
|
|
* When PREEMPT_COUNT disabled we can't reliably detect if it's
|
|
* safe to schedule (e.g. calling printk while holding a spin_lock),
|
|
* because preempt_disable()/preempt_enable() are just barriers there
|
|
* and preempt_count() is always 0.
|
|
*
|
|
* RCU read sections have a separate preemption counter when
|
|
* PREEMPT_RCU enabled thus we must take extra care and check
|
|
* rcu_preempt_depth(), otherwise RCU read sections modify
|
|
* preempt_count().
|
|
*/
|
|
console_may_schedule = !oops_in_progress &&
|
|
preemptible() &&
|
|
!rcu_preempt_depth();
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(console_trylock);
|
|
|
|
int is_console_locked(void)
|
|
{
|
|
return console_locked;
|
|
}
|
|
|
|
/*
|
|
* Check if we have any console that is capable of printing while cpu is
|
|
* booting or shutting down. Requires console_sem.
|
|
*/
|
|
static int have_callable_console(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con)
|
|
if ((con->flags & CON_ENABLED) &&
|
|
(con->flags & CON_ANYTIME))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Can we actually use the console at this time on this cpu?
|
|
*
|
|
* Console drivers may assume that per-cpu resources have been allocated. So
|
|
* unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
|
|
* call them until this CPU is officially up.
|
|
*/
|
|
static inline int can_use_console(void)
|
|
{
|
|
return cpu_online(raw_smp_processor_id()) || have_callable_console();
|
|
}
|
|
|
|
static void console_cont_flush(char *text, size_t size)
|
|
{
|
|
unsigned long flags;
|
|
size_t len;
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
|
|
if (!cont.len)
|
|
goto out;
|
|
|
|
/*
|
|
* We still queue earlier records, likely because the console was
|
|
* busy. The earlier ones need to be printed before this one, we
|
|
* did not flush any fragment so far, so just let it queue up.
|
|
*/
|
|
if (console_seq < log_next_seq && !cont.cons)
|
|
goto out;
|
|
|
|
len = cont_print_text(text, size);
|
|
raw_spin_unlock(&logbuf_lock);
|
|
stop_critical_timings();
|
|
call_console_drivers(cont.level, NULL, 0, text, len);
|
|
start_critical_timings();
|
|
local_irq_restore(flags);
|
|
return;
|
|
out:
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
}
|
|
|
|
/**
|
|
* console_unlock - unlock the console system
|
|
*
|
|
* Releases the console_lock which the caller holds on the console system
|
|
* and the console driver list.
|
|
*
|
|
* While the console_lock was held, console output may have been buffered
|
|
* by printk(). If this is the case, console_unlock(); emits
|
|
* the output prior to releasing the lock.
|
|
*
|
|
* If there is output waiting, we wake /dev/kmsg and syslog() users.
|
|
*
|
|
* console_unlock(); may be called from any context.
|
|
*/
|
|
void console_unlock(void)
|
|
{
|
|
static char ext_text[CONSOLE_EXT_LOG_MAX];
|
|
static char text[LOG_LINE_MAX + PREFIX_MAX];
|
|
static u64 seen_seq;
|
|
unsigned long flags;
|
|
bool wake_klogd = false;
|
|
bool do_cond_resched, retry;
|
|
|
|
if (console_suspended) {
|
|
up_console_sem();
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Console drivers are called under logbuf_lock, 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.
|
|
*/
|
|
do_cond_resched = console_may_schedule;
|
|
console_may_schedule = 0;
|
|
|
|
again:
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/* flush buffered message fragment immediately to console */
|
|
console_cont_flush(text, sizeof(text));
|
|
|
|
for (;;) {
|
|
struct printk_log *msg;
|
|
size_t ext_len = 0;
|
|
size_t len;
|
|
int level;
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
if (seen_seq != log_next_seq) {
|
|
wake_klogd = true;
|
|
seen_seq = log_next_seq;
|
|
}
|
|
|
|
if (console_seq < log_first_seq) {
|
|
len = sprintf(text, "** %u printk messages dropped ** ",
|
|
(unsigned)(log_first_seq - console_seq));
|
|
|
|
/* messages are gone, move to first one */
|
|
console_seq = log_first_seq;
|
|
console_idx = log_first_idx;
|
|
console_prev = 0;
|
|
} else {
|
|
len = 0;
|
|
}
|
|
skip:
|
|
if (console_seq == log_next_seq)
|
|
break;
|
|
|
|
msg = log_from_idx(console_idx);
|
|
if (msg->flags & LOG_NOCONS) {
|
|
/*
|
|
* Skip record we have buffered and already printed
|
|
* directly to the console when we received it.
|
|
*/
|
|
console_idx = log_next(console_idx);
|
|
console_seq++;
|
|
/*
|
|
* We will get here again when we register a new
|
|
* CON_PRINTBUFFER console. Clear the flag so we
|
|
* will properly dump everything later.
|
|
*/
|
|
msg->flags &= ~LOG_NOCONS;
|
|
console_prev = msg->flags;
|
|
goto skip;
|
|
}
|
|
|
|
level = msg->level;
|
|
len += msg_print_text(msg, console_prev, false,
|
|
text + len, sizeof(text) - len);
|
|
if (nr_ext_console_drivers) {
|
|
ext_len = msg_print_ext_header(ext_text,
|
|
sizeof(ext_text),
|
|
msg, console_seq, console_prev);
|
|
ext_len += msg_print_ext_body(ext_text + ext_len,
|
|
sizeof(ext_text) - ext_len,
|
|
log_dict(msg), msg->dict_len,
|
|
log_text(msg), msg->text_len);
|
|
}
|
|
console_idx = log_next(console_idx);
|
|
console_seq++;
|
|
console_prev = msg->flags;
|
|
raw_spin_unlock(&logbuf_lock);
|
|
|
|
stop_critical_timings(); /* don't trace print latency */
|
|
call_console_drivers(level, ext_text, ext_len, text, len);
|
|
start_critical_timings();
|
|
local_irq_restore(flags);
|
|
|
|
if (do_cond_resched)
|
|
cond_resched();
|
|
}
|
|
console_locked = 0;
|
|
|
|
/* Release the exclusive_console once it is used */
|
|
if (unlikely(exclusive_console))
|
|
exclusive_console = NULL;
|
|
|
|
raw_spin_unlock(&logbuf_lock);
|
|
|
|
up_console_sem();
|
|
|
|
/*
|
|
* Someone could have filled up the buffer again, so re-check if there's
|
|
* something to flush. In case we cannot trylock the console_sem again,
|
|
* there's a new owner and the console_unlock() from them will do the
|
|
* flush, no worries.
|
|
*/
|
|
raw_spin_lock(&logbuf_lock);
|
|
retry = console_seq != log_next_seq;
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
|
|
if (retry && console_trylock())
|
|
goto again;
|
|
|
|
if (wake_klogd)
|
|
wake_up_klogd();
|
|
}
|
|
EXPORT_SYMBOL(console_unlock);
|
|
|
|
/**
|
|
* console_conditional_schedule - yield the CPU if required
|
|
*
|
|
* If the console code is currently allowed to sleep, and
|
|
* if this CPU should yield the CPU to another task, do
|
|
* so here.
|
|
*
|
|
* Must be called within console_lock();.
|
|
*/
|
|
void __sched console_conditional_schedule(void)
|
|
{
|
|
if (console_may_schedule)
|
|
cond_resched();
|
|
}
|
|
EXPORT_SYMBOL(console_conditional_schedule);
|
|
|
|
void console_unblank(void)
|
|
{
|
|
struct console *c;
|
|
|
|
/*
|
|
* console_unblank can no longer be called in interrupt context unless
|
|
* oops_in_progress is set to 1..
|
|
*/
|
|
if (oops_in_progress) {
|
|
if (down_trylock_console_sem() != 0)
|
|
return;
|
|
} else
|
|
console_lock();
|
|
|
|
console_locked = 1;
|
|
console_may_schedule = 0;
|
|
for_each_console(c)
|
|
if ((c->flags & CON_ENABLED) && c->unblank)
|
|
c->unblank();
|
|
console_unlock();
|
|
}
|
|
|
|
/**
|
|
* console_flush_on_panic - flush console content on panic
|
|
*
|
|
* Immediately output all pending messages no matter what.
|
|
*/
|
|
void console_flush_on_panic(void)
|
|
{
|
|
/*
|
|
* If someone else is holding the console lock, trylock will fail
|
|
* and may_schedule may be set. Ignore and proceed to unlock so
|
|
* that messages are flushed out. As this can be called from any
|
|
* context and we don't want to get preempted while flushing,
|
|
* ensure may_schedule is cleared.
|
|
*/
|
|
console_trylock();
|
|
console_may_schedule = 0;
|
|
console_unlock();
|
|
}
|
|
|
|
/*
|
|
* Return the console tty driver structure and its associated index
|
|
*/
|
|
struct tty_driver *console_device(int *index)
|
|
{
|
|
struct console *c;
|
|
struct tty_driver *driver = NULL;
|
|
|
|
console_lock();
|
|
for_each_console(c) {
|
|
if (!c->device)
|
|
continue;
|
|
driver = c->device(c, index);
|
|
if (driver)
|
|
break;
|
|
}
|
|
console_unlock();
|
|
return driver;
|
|
}
|
|
|
|
/*
|
|
* Prevent further output on the passed console device so that (for example)
|
|
* serial drivers can disable console output before suspending a port, and can
|
|
* re-enable output afterwards.
|
|
*/
|
|
void console_stop(struct console *console)
|
|
{
|
|
console_lock();
|
|
console->flags &= ~CON_ENABLED;
|
|
console_unlock();
|
|
}
|
|
EXPORT_SYMBOL(console_stop);
|
|
|
|
void console_start(struct console *console)
|
|
{
|
|
console_lock();
|
|
console->flags |= CON_ENABLED;
|
|
console_unlock();
|
|
}
|
|
EXPORT_SYMBOL(console_start);
|
|
|
|
static int __read_mostly keep_bootcon;
|
|
|
|
static int __init keep_bootcon_setup(char *str)
|
|
{
|
|
keep_bootcon = 1;
|
|
pr_info("debug: skip boot console de-registration.\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("keep_bootcon", keep_bootcon_setup);
|
|
|
|
/*
|
|
* The console driver calls this routine during kernel initialization
|
|
* to register the console printing procedure with printk() and to
|
|
* print any messages that were printed by the kernel before the
|
|
* console driver was initialized.
|
|
*
|
|
* This can happen pretty early during the boot process (because of
|
|
* early_printk) - sometimes before setup_arch() completes - be careful
|
|
* of what kernel features are used - they may not be initialised yet.
|
|
*
|
|
* There are two types of consoles - bootconsoles (early_printk) and
|
|
* "real" consoles (everything which is not a bootconsole) which are
|
|
* handled differently.
|
|
* - Any number of bootconsoles can be registered at any time.
|
|
* - As soon as a "real" console is registered, all bootconsoles
|
|
* will be unregistered automatically.
|
|
* - Once a "real" console is registered, any attempt to register a
|
|
* bootconsoles will be rejected
|
|
*/
|
|
void register_console(struct console *newcon)
|
|
{
|
|
int i;
|
|
unsigned long flags;
|
|
struct console *bcon = NULL;
|
|
struct console_cmdline *c;
|
|
|
|
if (console_drivers)
|
|
for_each_console(bcon)
|
|
if (WARN(bcon == newcon,
|
|
"console '%s%d' already registered\n",
|
|
bcon->name, bcon->index))
|
|
return;
|
|
|
|
/*
|
|
* before we register a new CON_BOOT console, make sure we don't
|
|
* already have a valid console
|
|
*/
|
|
if (console_drivers && newcon->flags & CON_BOOT) {
|
|
/* find the last or real console */
|
|
for_each_console(bcon) {
|
|
if (!(bcon->flags & CON_BOOT)) {
|
|
pr_info("Too late to register bootconsole %s%d\n",
|
|
newcon->name, newcon->index);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (console_drivers && console_drivers->flags & CON_BOOT)
|
|
bcon = console_drivers;
|
|
|
|
if (preferred_console < 0 || bcon || !console_drivers)
|
|
preferred_console = selected_console;
|
|
|
|
/*
|
|
* See if we want to use this console driver. If we
|
|
* didn't select a console we take the first one
|
|
* that registers here.
|
|
*/
|
|
if (preferred_console < 0) {
|
|
if (newcon->index < 0)
|
|
newcon->index = 0;
|
|
if (newcon->setup == NULL ||
|
|
newcon->setup(newcon, NULL) == 0) {
|
|
newcon->flags |= CON_ENABLED;
|
|
if (newcon->device) {
|
|
newcon->flags |= CON_CONSDEV;
|
|
preferred_console = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* See if this console matches one we selected on
|
|
* the command line.
|
|
*/
|
|
for (i = 0, c = console_cmdline;
|
|
i < MAX_CMDLINECONSOLES && c->name[0];
|
|
i++, c++) {
|
|
if (!newcon->match ||
|
|
newcon->match(newcon, c->name, c->index, c->options) != 0) {
|
|
/* default matching */
|
|
BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
|
|
if (strcmp(c->name, newcon->name) != 0)
|
|
continue;
|
|
if (newcon->index >= 0 &&
|
|
newcon->index != c->index)
|
|
continue;
|
|
if (newcon->index < 0)
|
|
newcon->index = c->index;
|
|
|
|
if (_braille_register_console(newcon, c))
|
|
return;
|
|
|
|
if (newcon->setup &&
|
|
newcon->setup(newcon, c->options) != 0)
|
|
break;
|
|
}
|
|
|
|
newcon->flags |= CON_ENABLED;
|
|
if (i == selected_console) {
|
|
newcon->flags |= CON_CONSDEV;
|
|
preferred_console = selected_console;
|
|
}
|
|
break;
|
|
}
|
|
|
|
if (!(newcon->flags & CON_ENABLED))
|
|
return;
|
|
|
|
/*
|
|
* If we have a bootconsole, and are switching to a real console,
|
|
* don't print everything out again, since when the boot console, and
|
|
* the real console are the same physical device, it's annoying to
|
|
* see the beginning boot messages twice
|
|
*/
|
|
if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
|
|
newcon->flags &= ~CON_PRINTBUFFER;
|
|
|
|
/*
|
|
* Put this console in the list - keep the
|
|
* preferred driver at the head of the list.
|
|
*/
|
|
console_lock();
|
|
if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
|
|
newcon->next = console_drivers;
|
|
console_drivers = newcon;
|
|
if (newcon->next)
|
|
newcon->next->flags &= ~CON_CONSDEV;
|
|
} else {
|
|
newcon->next = console_drivers->next;
|
|
console_drivers->next = newcon;
|
|
}
|
|
|
|
if (newcon->flags & CON_EXTENDED)
|
|
if (!nr_ext_console_drivers++)
|
|
pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n");
|
|
|
|
if (newcon->flags & CON_PRINTBUFFER) {
|
|
/*
|
|
* console_unlock(); will print out the buffered messages
|
|
* for us.
|
|
*/
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
console_seq = syslog_seq;
|
|
console_idx = syslog_idx;
|
|
console_prev = syslog_prev;
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
/*
|
|
* We're about to replay the log buffer. Only do this to the
|
|
* just-registered console to avoid excessive message spam to
|
|
* the already-registered consoles.
|
|
*/
|
|
exclusive_console = newcon;
|
|
}
|
|
console_unlock();
|
|
console_sysfs_notify();
|
|
|
|
/*
|
|
* By unregistering the bootconsoles after we enable the real console
|
|
* we get the "console xxx enabled" message on all the consoles -
|
|
* boot consoles, real consoles, etc - this is to ensure that end
|
|
* users know there might be something in the kernel's log buffer that
|
|
* went to the bootconsole (that they do not see on the real console)
|
|
*/
|
|
pr_info("%sconsole [%s%d] enabled\n",
|
|
(newcon->flags & CON_BOOT) ? "boot" : "" ,
|
|
newcon->name, newcon->index);
|
|
if (bcon &&
|
|
((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
|
|
!keep_bootcon) {
|
|
/* We need to iterate through all boot consoles, to make
|
|
* sure we print everything out, before we unregister them.
|
|
*/
|
|
for_each_console(bcon)
|
|
if (bcon->flags & CON_BOOT)
|
|
unregister_console(bcon);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(register_console);
|
|
|
|
int unregister_console(struct console *console)
|
|
{
|
|
struct console *a, *b;
|
|
int res;
|
|
|
|
pr_info("%sconsole [%s%d] disabled\n",
|
|
(console->flags & CON_BOOT) ? "boot" : "" ,
|
|
console->name, console->index);
|
|
|
|
res = _braille_unregister_console(console);
|
|
if (res)
|
|
return res;
|
|
|
|
res = 1;
|
|
console_lock();
|
|
if (console_drivers == console) {
|
|
console_drivers=console->next;
|
|
res = 0;
|
|
} else if (console_drivers) {
|
|
for (a=console_drivers->next, b=console_drivers ;
|
|
a; b=a, a=b->next) {
|
|
if (a == console) {
|
|
b->next = a->next;
|
|
res = 0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!res && (console->flags & CON_EXTENDED))
|
|
nr_ext_console_drivers--;
|
|
|
|
/*
|
|
* If this isn't the last console and it has CON_CONSDEV set, we
|
|
* need to set it on the next preferred console.
|
|
*/
|
|
if (console_drivers != NULL && console->flags & CON_CONSDEV)
|
|
console_drivers->flags |= CON_CONSDEV;
|
|
|
|
console->flags &= ~CON_ENABLED;
|
|
console_unlock();
|
|
console_sysfs_notify();
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(unregister_console);
|
|
|
|
/*
|
|
* 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 code exists elsewhere to get
|
|
* rid of the boot console as soon as the proper console shows up, so there
|
|
* won't be side-effects from postponing the removal.
|
|
*/
|
|
static int __init printk_late_init(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con) {
|
|
if (!keep_bootcon && con->flags & CON_BOOT) {
|
|
/*
|
|
* Make sure to unregister boot consoles whose data
|
|
* resides in the init section before the init section
|
|
* is discarded. Boot consoles whose data will stick
|
|
* around will automatically be unregistered when the
|
|
* proper console replaces them.
|
|
*/
|
|
if (init_section_intersects(con, sizeof(*con)))
|
|
unregister_console(con);
|
|
}
|
|
}
|
|
hotcpu_notifier(console_cpu_notify, 0);
|
|
return 0;
|
|
}
|
|
late_initcall(printk_late_init);
|
|
|
|
#if defined CONFIG_PRINTK
|
|
/*
|
|
* Delayed printk version, for scheduler-internal messages:
|
|
*/
|
|
#define PRINTK_PENDING_WAKEUP 0x01
|
|
#define PRINTK_PENDING_OUTPUT 0x02
|
|
|
|
static DEFINE_PER_CPU(int, printk_pending);
|
|
|
|
static void wake_up_klogd_work_func(struct irq_work *irq_work)
|
|
{
|
|
int pending = __this_cpu_xchg(printk_pending, 0);
|
|
|
|
if (pending & PRINTK_PENDING_OUTPUT) {
|
|
/* If trylock fails, someone else is doing the printing */
|
|
if (console_trylock())
|
|
console_unlock();
|
|
}
|
|
|
|
if (pending & PRINTK_PENDING_WAKEUP)
|
|
wake_up_interruptible(&log_wait);
|
|
}
|
|
|
|
static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
|
|
.func = wake_up_klogd_work_func,
|
|
.flags = IRQ_WORK_LAZY,
|
|
};
|
|
|
|
void wake_up_klogd(void)
|
|
{
|
|
preempt_disable();
|
|
if (waitqueue_active(&log_wait)) {
|
|
this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
|
|
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
|
|
}
|
|
preempt_enable();
|
|
}
|
|
|
|
int printk_deferred(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
preempt_disable();
|
|
va_start(args, fmt);
|
|
r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
|
|
va_end(args);
|
|
|
|
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
|
|
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
|
|
preempt_enable();
|
|
|
|
return r;
|
|
}
|
|
|
|
/*
|
|
* printk rate limiting, lifted from the networking subsystem.
|
|
*
|
|
* This enforces a rate limit: not more than 10 kernel messages
|
|
* every 5s to make a denial-of-service attack impossible.
|
|
*/
|
|
DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
|
|
|
|
int __printk_ratelimit(const char *func)
|
|
{
|
|
return ___ratelimit(&printk_ratelimit_state, func);
|
|
}
|
|
EXPORT_SYMBOL(__printk_ratelimit);
|
|
|
|
/**
|
|
* printk_timed_ratelimit - caller-controlled printk ratelimiting
|
|
* @caller_jiffies: pointer to caller's state
|
|
* @interval_msecs: minimum interval between prints
|
|
*
|
|
* printk_timed_ratelimit() returns true if more than @interval_msecs
|
|
* milliseconds have elapsed since the last time printk_timed_ratelimit()
|
|
* returned true.
|
|
*/
|
|
bool printk_timed_ratelimit(unsigned long *caller_jiffies,
|
|
unsigned int interval_msecs)
|
|
{
|
|
unsigned long elapsed = jiffies - *caller_jiffies;
|
|
|
|
if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs))
|
|
return false;
|
|
|
|
*caller_jiffies = jiffies;
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(printk_timed_ratelimit);
|
|
|
|
static DEFINE_SPINLOCK(dump_list_lock);
|
|
static LIST_HEAD(dump_list);
|
|
|
|
/**
|
|
* kmsg_dump_register - register a kernel log dumper.
|
|
* @dumper: pointer to the kmsg_dumper structure
|
|
*
|
|
* Adds a kernel log dumper to the system. The dump callback in the
|
|
* structure will be called when the kernel oopses or panics and must be
|
|
* set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
|
|
*/
|
|
int kmsg_dump_register(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
int err = -EBUSY;
|
|
|
|
/* The dump callback needs to be set */
|
|
if (!dumper->dump)
|
|
return -EINVAL;
|
|
|
|
spin_lock_irqsave(&dump_list_lock, flags);
|
|
/* Don't allow registering multiple times */
|
|
if (!dumper->registered) {
|
|
dumper->registered = 1;
|
|
list_add_tail_rcu(&dumper->list, &dump_list);
|
|
err = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dump_list_lock, flags);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_register);
|
|
|
|
/**
|
|
* kmsg_dump_unregister - unregister a kmsg dumper.
|
|
* @dumper: pointer to the kmsg_dumper structure
|
|
*
|
|
* Removes a dump device from the system. Returns zero on success and
|
|
* %-EINVAL otherwise.
|
|
*/
|
|
int kmsg_dump_unregister(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
int err = -EINVAL;
|
|
|
|
spin_lock_irqsave(&dump_list_lock, flags);
|
|
if (dumper->registered) {
|
|
dumper->registered = 0;
|
|
list_del_rcu(&dumper->list);
|
|
err = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dump_list_lock, flags);
|
|
synchronize_rcu();
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
|
|
|
|
static bool always_kmsg_dump;
|
|
module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
|
|
|
|
/**
|
|
* kmsg_dump - dump kernel log to kernel message dumpers.
|
|
* @reason: the reason (oops, panic etc) for dumping
|
|
*
|
|
* Call each of the registered dumper's dump() callback, which can
|
|
* retrieve the kmsg records with kmsg_dump_get_line() or
|
|
* kmsg_dump_get_buffer().
|
|
*/
|
|
void kmsg_dump(enum kmsg_dump_reason reason)
|
|
{
|
|
struct kmsg_dumper *dumper;
|
|
unsigned long flags;
|
|
|
|
if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
|
|
return;
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(dumper, &dump_list, list) {
|
|
if (dumper->max_reason && reason > dumper->max_reason)
|
|
continue;
|
|
|
|
/* initialize iterator with data about the stored records */
|
|
dumper->active = true;
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
dumper->cur_seq = clear_seq;
|
|
dumper->cur_idx = clear_idx;
|
|
dumper->next_seq = log_next_seq;
|
|
dumper->next_idx = log_next_idx;
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
|
|
/* invoke dumper which will iterate over records */
|
|
dumper->dump(dumper, reason);
|
|
|
|
/* reset iterator */
|
|
dumper->active = false;
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
|
|
* @dumper: registered kmsg dumper
|
|
* @syslog: include the "<4>" prefixes
|
|
* @line: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len: length of line placed into buffer
|
|
*
|
|
* Start at the beginning of the kmsg buffer, with the oldest kmsg
|
|
* record, and copy one record into the provided buffer.
|
|
*
|
|
* Consecutive calls will return the next available record moving
|
|
* towards the end of the buffer with the youngest messages.
|
|
*
|
|
* A return value of FALSE indicates that there are no more records to
|
|
* read.
|
|
*
|
|
* The function is similar to kmsg_dump_get_line(), but grabs no locks.
|
|
*/
|
|
bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
|
|
char *line, size_t size, size_t *len)
|
|
{
|
|
struct printk_log *msg;
|
|
size_t l = 0;
|
|
bool ret = false;
|
|
|
|
if (!dumper->active)
|
|
goto out;
|
|
|
|
if (dumper->cur_seq < log_first_seq) {
|
|
/* messages are gone, move to first available one */
|
|
dumper->cur_seq = log_first_seq;
|
|
dumper->cur_idx = log_first_idx;
|
|
}
|
|
|
|
/* last entry */
|
|
if (dumper->cur_seq >= log_next_seq)
|
|
goto out;
|
|
|
|
msg = log_from_idx(dumper->cur_idx);
|
|
l = msg_print_text(msg, 0, syslog, line, size);
|
|
|
|
dumper->cur_idx = log_next(dumper->cur_idx);
|
|
dumper->cur_seq++;
|
|
ret = true;
|
|
out:
|
|
if (len)
|
|
*len = l;
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_get_line - retrieve one kmsg log line
|
|
* @dumper: registered kmsg dumper
|
|
* @syslog: include the "<4>" prefixes
|
|
* @line: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len: length of line placed into buffer
|
|
*
|
|
* Start at the beginning of the kmsg buffer, with the oldest kmsg
|
|
* record, and copy one record into the provided buffer.
|
|
*
|
|
* Consecutive calls will return the next available record moving
|
|
* towards the end of the buffer with the youngest messages.
|
|
*
|
|
* A return value of FALSE indicates that there are no more records to
|
|
* read.
|
|
*/
|
|
bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
|
|
char *line, size_t size, size_t *len)
|
|
{
|
|
unsigned long flags;
|
|
bool ret;
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
|
|
|
|
/**
|
|
* kmsg_dump_get_buffer - copy kmsg log lines
|
|
* @dumper: registered kmsg dumper
|
|
* @syslog: include the "<4>" prefixes
|
|
* @buf: buffer to copy the line to
|
|
* @size: maximum size of the buffer
|
|
* @len: length of line placed into buffer
|
|
*
|
|
* Start at the end of the kmsg buffer and fill the provided buffer
|
|
* with as many of the the *youngest* kmsg records that fit into it.
|
|
* If the buffer is large enough, all available kmsg records will be
|
|
* copied with a single call.
|
|
*
|
|
* Consecutive calls will fill the buffer with the next block of
|
|
* available older records, not including the earlier retrieved ones.
|
|
*
|
|
* A return value of FALSE indicates that there are no more records to
|
|
* read.
|
|
*/
|
|
bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
|
|
char *buf, size_t size, size_t *len)
|
|
{
|
|
unsigned long flags;
|
|
u64 seq;
|
|
u32 idx;
|
|
u64 next_seq;
|
|
u32 next_idx;
|
|
enum log_flags prev;
|
|
size_t l = 0;
|
|
bool ret = false;
|
|
|
|
if (!dumper->active)
|
|
goto out;
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
if (dumper->cur_seq < log_first_seq) {
|
|
/* messages are gone, move to first available one */
|
|
dumper->cur_seq = log_first_seq;
|
|
dumper->cur_idx = log_first_idx;
|
|
}
|
|
|
|
/* last entry */
|
|
if (dumper->cur_seq >= dumper->next_seq) {
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
goto out;
|
|
}
|
|
|
|
/* calculate length of entire buffer */
|
|
seq = dumper->cur_seq;
|
|
idx = dumper->cur_idx;
|
|
prev = 0;
|
|
while (seq < dumper->next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
l += msg_print_text(msg, prev, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
prev = msg->flags;
|
|
}
|
|
|
|
/* move first record forward until length fits into the buffer */
|
|
seq = dumper->cur_seq;
|
|
idx = dumper->cur_idx;
|
|
prev = 0;
|
|
while (l > size && seq < dumper->next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
l -= msg_print_text(msg, prev, true, NULL, 0);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
prev = msg->flags;
|
|
}
|
|
|
|
/* last message in next interation */
|
|
next_seq = seq;
|
|
next_idx = idx;
|
|
|
|
l = 0;
|
|
while (seq < dumper->next_seq) {
|
|
struct printk_log *msg = log_from_idx(idx);
|
|
|
|
l += msg_print_text(msg, prev, syslog, buf + l, size - l);
|
|
idx = log_next(idx);
|
|
seq++;
|
|
prev = msg->flags;
|
|
}
|
|
|
|
dumper->next_seq = next_seq;
|
|
dumper->next_idx = next_idx;
|
|
ret = true;
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
out:
|
|
if (len)
|
|
*len = l;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
|
|
|
|
/**
|
|
* kmsg_dump_rewind_nolock - reset the interator (unlocked version)
|
|
* @dumper: registered kmsg dumper
|
|
*
|
|
* Reset the dumper's iterator so that kmsg_dump_get_line() and
|
|
* kmsg_dump_get_buffer() can be called again and used multiple
|
|
* times within the same dumper.dump() callback.
|
|
*
|
|
* The function is similar to kmsg_dump_rewind(), but grabs no locks.
|
|
*/
|
|
void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
|
|
{
|
|
dumper->cur_seq = clear_seq;
|
|
dumper->cur_idx = clear_idx;
|
|
dumper->next_seq = log_next_seq;
|
|
dumper->next_idx = log_next_idx;
|
|
}
|
|
|
|
/**
|
|
* kmsg_dump_rewind - reset the interator
|
|
* @dumper: registered kmsg dumper
|
|
*
|
|
* Reset the dumper's iterator so that kmsg_dump_get_line() and
|
|
* kmsg_dump_get_buffer() can be called again and used multiple
|
|
* times within the same dumper.dump() callback.
|
|
*/
|
|
void kmsg_dump_rewind(struct kmsg_dumper *dumper)
|
|
{
|
|
unsigned long flags;
|
|
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
kmsg_dump_rewind_nolock(dumper);
|
|
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
|
|
|
|
static char dump_stack_arch_desc_str[128];
|
|
|
|
/**
|
|
* dump_stack_set_arch_desc - set arch-specific str to show with task dumps
|
|
* @fmt: printf-style format string
|
|
* @...: arguments for the format string
|
|
*
|
|
* The configured string will be printed right after utsname during task
|
|
* dumps. Usually used to add arch-specific system identifiers. If an
|
|
* arch wants to make use of such an ID string, it should initialize this
|
|
* as soon as possible during boot.
|
|
*/
|
|
void __init dump_stack_set_arch_desc(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
|
|
va_start(args, fmt);
|
|
vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
|
|
fmt, args);
|
|
va_end(args);
|
|
}
|
|
|
|
/**
|
|
* dump_stack_print_info - print generic debug info for dump_stack()
|
|
* @log_lvl: log level
|
|
*
|
|
* Arch-specific dump_stack() implementations can use this function to
|
|
* print out the same debug information as the generic dump_stack().
|
|
*/
|
|
void dump_stack_print_info(const char *log_lvl)
|
|
{
|
|
printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
|
|
log_lvl, raw_smp_processor_id(), current->pid, current->comm,
|
|
print_tainted(), init_utsname()->release,
|
|
(int)strcspn(init_utsname()->version, " "),
|
|
init_utsname()->version);
|
|
|
|
if (dump_stack_arch_desc_str[0] != '\0')
|
|
printk("%sHardware name: %s\n",
|
|
log_lvl, dump_stack_arch_desc_str);
|
|
|
|
print_worker_info(log_lvl, current);
|
|
}
|
|
|
|
/**
|
|
* show_regs_print_info - print generic debug info for show_regs()
|
|
* @log_lvl: log level
|
|
*
|
|
* show_regs() implementations can use this function to print out generic
|
|
* debug information.
|
|
*/
|
|
void show_regs_print_info(const char *log_lvl)
|
|
{
|
|
dump_stack_print_info(log_lvl);
|
|
|
|
printk("%stask: %p ti: %p task.ti: %p\n",
|
|
log_lvl, current, current_thread_info(),
|
|
task_thread_info(current));
|
|
}
|
|
|
|
#endif
|