mirror of https://gitee.com/openkylin/linux.git
1763 lines
44 KiB
C
1763 lines
44 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 <asm/uaccess.h>
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/*
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* Architectures can override it:
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*/
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void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
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{
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}
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#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
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/* printk's without a loglevel use this.. */
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#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
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/* We show everything that is MORE important than this.. */
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#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
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#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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int console_printk[4] = {
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DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
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DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
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MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
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DEFAULT_CONSOLE_LOGLEVEL, /* 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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/*
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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 are racing, but it helps tracking those weird code
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* path 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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* logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
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* It is also used in interesting ways to provide interlocking in
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* console_unlock();.
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*/
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static DEFINE_RAW_SPINLOCK(logbuf_lock);
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#define LOG_BUF_MASK (log_buf_len-1)
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#define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
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/*
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* The indices into log_buf are not constrained to log_buf_len - they
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* must be masked before subscripting
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*/
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static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */
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static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */
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static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */
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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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struct console_cmdline
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{
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char name[8]; /* Name of the driver */
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int index; /* Minor dev. to use */
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char *options; /* Options for the driver */
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#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
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char *brl_options; /* Options for braille driver */
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#endif
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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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#ifdef CONFIG_PRINTK
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static char __log_buf[__LOG_BUF_LEN];
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static char *log_buf = __log_buf;
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static int log_buf_len = __LOG_BUF_LEN;
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static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
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static int saved_console_loglevel = -1;
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#ifdef CONFIG_KEXEC
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/*
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* This appends the listed symbols to /proc/vmcoreinfo
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*
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* /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
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* obtain access to symbols that are otherwise very difficult to locate. These
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* symbols are specifically used so that utilities can access and extract the
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* dmesg log from a vmcore file after a crash.
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*/
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void log_buf_kexec_setup(void)
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{
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VMCOREINFO_SYMBOL(log_buf);
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VMCOREINFO_SYMBOL(log_end);
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VMCOREINFO_SYMBOL(log_buf_len);
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VMCOREINFO_SYMBOL(logged_chars);
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}
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#endif
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/* requested log_buf_len from kernel cmdline */
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static unsigned long __initdata new_log_buf_len;
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/* save requested log_buf_len since it's too early to process it */
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static int __init log_buf_len_setup(char *str)
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{
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unsigned size = memparse(str, &str);
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if (size)
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size = roundup_pow_of_two(size);
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if (size > log_buf_len)
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new_log_buf_len = size;
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return 0;
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}
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early_param("log_buf_len", log_buf_len_setup);
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void __init setup_log_buf(int early)
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{
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unsigned long flags;
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unsigned start, dest_idx, offset;
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char *new_log_buf;
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int free;
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if (!new_log_buf_len)
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return;
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if (early) {
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unsigned long mem;
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mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
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if (!mem)
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return;
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new_log_buf = __va(mem);
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} else {
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new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
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}
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if (unlikely(!new_log_buf)) {
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pr_err("log_buf_len: %ld bytes not available\n",
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new_log_buf_len);
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return;
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}
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raw_spin_lock_irqsave(&logbuf_lock, flags);
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log_buf_len = new_log_buf_len;
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log_buf = new_log_buf;
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new_log_buf_len = 0;
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free = __LOG_BUF_LEN - log_end;
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offset = start = min(con_start, log_start);
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dest_idx = 0;
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while (start != log_end) {
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unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1);
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log_buf[dest_idx] = __log_buf[log_idx_mask];
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start++;
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dest_idx++;
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}
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log_start -= offset;
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con_start -= offset;
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log_end -= offset;
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raw_spin_unlock_irqrestore(&logbuf_lock, flags);
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pr_info("log_buf_len: %d\n", log_buf_len);
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pr_info("early log buf free: %d(%d%%)\n",
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free, (free * 100) / __LOG_BUF_LEN);
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}
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#ifdef CONFIG_BOOT_PRINTK_DELAY
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static int boot_delay; /* msecs delay after each printk during bootup */
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static unsigned long long loops_per_msec; /* based on boot_delay */
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static int __init boot_delay_setup(char *str)
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{
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unsigned long lpj;
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lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
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loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
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get_option(&str, &boot_delay);
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if (boot_delay > 10 * 1000)
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boot_delay = 0;
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pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
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"HZ: %d, loops_per_msec: %llu\n",
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boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
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return 1;
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}
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__setup("boot_delay=", boot_delay_setup);
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static void boot_delay_msec(void)
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{
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unsigned long long k;
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unsigned long timeout;
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if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
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return;
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k = (unsigned long long)loops_per_msec * boot_delay;
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timeout = jiffies + msecs_to_jiffies(boot_delay);
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while (k) {
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k--;
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cpu_relax();
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/*
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* use (volatile) jiffies to prevent
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* compiler reduction; loop termination via jiffies
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* is secondary and may or may not happen.
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*/
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if (time_after(jiffies, timeout))
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break;
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touch_nmi_watchdog();
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}
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}
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#else
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static inline void boot_delay_msec(void)
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{
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}
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#endif
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#ifdef CONFIG_SECURITY_DMESG_RESTRICT
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int dmesg_restrict = 1;
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#else
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int dmesg_restrict;
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#endif
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static int syslog_action_restricted(int type)
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{
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if (dmesg_restrict)
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return 1;
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/* Unless restricted, we allow "read all" and "get buffer size" for everybody */
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return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER;
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}
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static int check_syslog_permissions(int type, bool from_file)
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{
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/*
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* If this is from /proc/kmsg and we've already opened it, then we've
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* already done the capabilities checks at open time.
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*/
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if (from_file && type != SYSLOG_ACTION_OPEN)
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return 0;
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if (syslog_action_restricted(type)) {
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if (capable(CAP_SYSLOG))
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return 0;
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/* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
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if (capable(CAP_SYS_ADMIN)) {
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printk_once(KERN_WARNING "%s (%d): "
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"Attempt to access syslog with CAP_SYS_ADMIN "
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"but no CAP_SYSLOG (deprecated).\n",
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current->comm, task_pid_nr(current));
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return 0;
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}
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return -EPERM;
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}
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return 0;
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}
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int do_syslog(int type, char __user *buf, int len, bool from_file)
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{
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unsigned i, j, limit, count;
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int do_clear = 0;
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char c;
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int error;
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error = check_syslog_permissions(type, from_file);
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if (error)
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goto out;
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error = security_syslog(type);
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if (error)
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return error;
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switch (type) {
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case SYSLOG_ACTION_CLOSE: /* Close log */
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break;
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case SYSLOG_ACTION_OPEN: /* Open log */
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break;
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case SYSLOG_ACTION_READ: /* Read from log */
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error = -EINVAL;
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if (!buf || len < 0)
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goto out;
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error = 0;
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if (!len)
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goto out;
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if (!access_ok(VERIFY_WRITE, buf, len)) {
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error = -EFAULT;
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goto out;
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}
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error = wait_event_interruptible(log_wait,
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(log_start - log_end));
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if (error)
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goto out;
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i = 0;
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raw_spin_lock_irq(&logbuf_lock);
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while (!error && (log_start != log_end) && i < len) {
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c = LOG_BUF(log_start);
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log_start++;
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raw_spin_unlock_irq(&logbuf_lock);
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error = __put_user(c,buf);
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buf++;
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i++;
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cond_resched();
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raw_spin_lock_irq(&logbuf_lock);
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}
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raw_spin_unlock_irq(&logbuf_lock);
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if (!error)
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error = i;
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break;
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/* Read/clear last kernel messages */
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case SYSLOG_ACTION_READ_CLEAR:
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do_clear = 1;
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/* FALL THRU */
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/* Read last kernel messages */
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case SYSLOG_ACTION_READ_ALL:
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error = -EINVAL;
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if (!buf || len < 0)
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goto out;
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error = 0;
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if (!len)
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goto out;
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if (!access_ok(VERIFY_WRITE, buf, len)) {
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error = -EFAULT;
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goto out;
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}
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count = len;
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if (count > log_buf_len)
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count = log_buf_len;
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raw_spin_lock_irq(&logbuf_lock);
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if (count > logged_chars)
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count = logged_chars;
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if (do_clear)
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logged_chars = 0;
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limit = log_end;
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/*
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* __put_user() could sleep, and while we sleep
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* printk() could overwrite the messages
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* we try to copy to user space. Therefore
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* the messages are copied in reverse. <manfreds>
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*/
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for (i = 0; i < count && !error; i++) {
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j = limit-1-i;
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if (j + log_buf_len < log_end)
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break;
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c = LOG_BUF(j);
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raw_spin_unlock_irq(&logbuf_lock);
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error = __put_user(c,&buf[count-1-i]);
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cond_resched();
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raw_spin_lock_irq(&logbuf_lock);
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}
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raw_spin_unlock_irq(&logbuf_lock);
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if (error)
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break;
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error = i;
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if (i != count) {
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int offset = count-error;
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/* buffer overflow during copy, correct user buffer. */
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for (i = 0; i < error; i++) {
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if (__get_user(c,&buf[i+offset]) ||
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__put_user(c,&buf[i])) {
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error = -EFAULT;
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break;
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}
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cond_resched();
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}
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}
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break;
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/* Clear ring buffer */
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case SYSLOG_ACTION_CLEAR:
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logged_chars = 0;
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break;
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/* Disable logging to console */
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case SYSLOG_ACTION_CONSOLE_OFF:
|
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if (saved_console_loglevel == -1)
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saved_console_loglevel = console_loglevel;
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console_loglevel = minimum_console_loglevel;
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break;
|
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/* Enable logging to console */
|
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case SYSLOG_ACTION_CONSOLE_ON:
|
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if (saved_console_loglevel != -1) {
|
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console_loglevel = saved_console_loglevel;
|
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saved_console_loglevel = -1;
|
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}
|
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break;
|
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/* Set level of messages printed to console */
|
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case SYSLOG_ACTION_CONSOLE_LEVEL:
|
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error = -EINVAL;
|
|
if (len < 1 || len > 8)
|
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goto out;
|
|
if (len < minimum_console_loglevel)
|
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len = minimum_console_loglevel;
|
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console_loglevel = len;
|
|
/* Implicitly re-enable logging to console */
|
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saved_console_loglevel = -1;
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error = 0;
|
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break;
|
|
/* Number of chars in the log buffer */
|
|
case SYSLOG_ACTION_SIZE_UNREAD:
|
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error = log_end - log_start;
|
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break;
|
|
/* Size of the log buffer */
|
|
case SYSLOG_ACTION_SIZE_BUFFER:
|
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error = log_buf_len;
|
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break;
|
|
default:
|
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error = -EINVAL;
|
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break;
|
|
}
|
|
out:
|
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return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
|
|
{
|
|
return do_syslog(type, buf, len, SYSLOG_FROM_CALL);
|
|
}
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
/* kdb dmesg command needs access to the syslog buffer. do_syslog()
|
|
* uses locks so it cannot be used during debugging. Just tell kdb
|
|
* where the start and end of the physical and logical logs are. This
|
|
* is equivalent to do_syslog(3).
|
|
*/
|
|
void kdb_syslog_data(char *syslog_data[4])
|
|
{
|
|
syslog_data[0] = log_buf;
|
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syslog_data[1] = log_buf + log_buf_len;
|
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syslog_data[2] = log_buf + log_end -
|
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(logged_chars < log_buf_len ? logged_chars : log_buf_len);
|
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syslog_data[3] = log_buf + log_end;
|
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}
|
|
#endif /* CONFIG_KGDB_KDB */
|
|
|
|
/*
|
|
* Call the console drivers on a range of log_buf
|
|
*/
|
|
static void __call_console_drivers(unsigned start, unsigned end)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con) {
|
|
if (exclusive_console && con != exclusive_console)
|
|
continue;
|
|
if ((con->flags & CON_ENABLED) && con->write &&
|
|
(cpu_online(smp_processor_id()) ||
|
|
(con->flags & CON_ANYTIME)))
|
|
con->write(con, &LOG_BUF(start), end - start);
|
|
}
|
|
}
|
|
|
|
static int __read_mostly ignore_loglevel;
|
|
|
|
static int __init ignore_loglevel_setup(char *str)
|
|
{
|
|
ignore_loglevel = 1;
|
|
printk(KERN_INFO "debug: ignoring loglevel setting.\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
early_param("ignore_loglevel", ignore_loglevel_setup);
|
|
module_param_named(ignore_loglevel, ignore_loglevel, bool, S_IRUGO | S_IWUSR);
|
|
MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to"
|
|
"print all kernel messages to the console.");
|
|
|
|
/*
|
|
* Write out chars from start to end - 1 inclusive
|
|
*/
|
|
static void _call_console_drivers(unsigned start,
|
|
unsigned end, int msg_log_level)
|
|
{
|
|
if ((msg_log_level < console_loglevel || ignore_loglevel) &&
|
|
console_drivers && start != end) {
|
|
if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
|
|
/* wrapped write */
|
|
__call_console_drivers(start & LOG_BUF_MASK,
|
|
log_buf_len);
|
|
__call_console_drivers(0, end & LOG_BUF_MASK);
|
|
} else {
|
|
__call_console_drivers(start, end);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the
|
|
* lower 3 bit are the log level, the rest are the log facility. In case
|
|
* userspace passes usual userspace syslog messages to /dev/kmsg or
|
|
* /dev/ttyprintk, the log prefix might contain the facility. Printk needs
|
|
* to extract the correct log level for in-kernel processing, and not mangle
|
|
* the original value.
|
|
*
|
|
* If a prefix is found, the length of the prefix is returned. If 'level' is
|
|
* passed, it will be filled in with the log level without a possible facility
|
|
* value. If 'special' is passed, the special printk prefix chars are accepted
|
|
* and returned. If no valid header is found, 0 is returned and the passed
|
|
* variables are not touched.
|
|
*/
|
|
static size_t log_prefix(const char *p, unsigned int *level, char *special)
|
|
{
|
|
unsigned int lev = 0;
|
|
char sp = '\0';
|
|
size_t len;
|
|
|
|
if (p[0] != '<' || !p[1])
|
|
return 0;
|
|
if (p[2] == '>') {
|
|
/* usual single digit level number or special char */
|
|
switch (p[1]) {
|
|
case '0' ... '7':
|
|
lev = p[1] - '0';
|
|
break;
|
|
case 'c': /* KERN_CONT */
|
|
case 'd': /* KERN_DEFAULT */
|
|
sp = p[1];
|
|
break;
|
|
default:
|
|
return 0;
|
|
}
|
|
len = 3;
|
|
} else {
|
|
/* multi digit including the level and facility number */
|
|
char *endp = NULL;
|
|
|
|
lev = (simple_strtoul(&p[1], &endp, 10) & 7);
|
|
if (endp == NULL || endp[0] != '>')
|
|
return 0;
|
|
len = (endp + 1) - p;
|
|
}
|
|
|
|
/* do not accept special char if not asked for */
|
|
if (sp && !special)
|
|
return 0;
|
|
|
|
if (special) {
|
|
*special = sp;
|
|
/* return special char, do not touch level */
|
|
if (sp)
|
|
return len;
|
|
}
|
|
|
|
if (level)
|
|
*level = lev;
|
|
return len;
|
|
}
|
|
|
|
/*
|
|
* 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(unsigned start, unsigned end)
|
|
{
|
|
unsigned cur_index, start_print;
|
|
static int msg_level = -1;
|
|
|
|
BUG_ON(((int)(start - end)) > 0);
|
|
|
|
cur_index = start;
|
|
start_print = start;
|
|
while (cur_index != end) {
|
|
if (msg_level < 0 && ((end - cur_index) > 2)) {
|
|
/* strip log prefix */
|
|
cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL);
|
|
start_print = cur_index;
|
|
}
|
|
while (cur_index != end) {
|
|
char c = LOG_BUF(cur_index);
|
|
|
|
cur_index++;
|
|
if (c == '\n') {
|
|
if (msg_level < 0) {
|
|
/*
|
|
* printk() has already given us loglevel tags in
|
|
* the buffer. This code is here in case the
|
|
* log buffer has wrapped right round and scribbled
|
|
* on those tags
|
|
*/
|
|
msg_level = default_message_loglevel;
|
|
}
|
|
_call_console_drivers(start_print, cur_index, msg_level);
|
|
msg_level = -1;
|
|
start_print = cur_index;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
_call_console_drivers(start_print, end, msg_level);
|
|
}
|
|
|
|
static void emit_log_char(char c)
|
|
{
|
|
LOG_BUF(log_end) = c;
|
|
log_end++;
|
|
if (log_end - log_start > log_buf_len)
|
|
log_start = log_end - log_buf_len;
|
|
if (log_end - con_start > log_buf_len)
|
|
con_start = log_end - log_buf_len;
|
|
if (logged_chars < log_buf_len)
|
|
logged_chars++;
|
|
}
|
|
|
|
/*
|
|
* Zap console related locks when oopsing. Only zap at most once
|
|
* every 10 seconds, to leave time for slow consoles to print a
|
|
* full oops.
|
|
*/
|
|
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);
|
|
}
|
|
|
|
#if defined(CONFIG_PRINTK_TIME)
|
|
static int printk_time = 1;
|
|
#else
|
|
static int printk_time = 0;
|
|
#endif
|
|
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
|
|
|
|
/* Check if we have any console registered that can be called early in boot. */
|
|
static int have_callable_console(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con)
|
|
if (con->flags & CON_ANYTIME)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* 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 int printk(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
if (unlikely(kdb_trap_printk)) {
|
|
va_start(args, fmt);
|
|
r = vkdb_printf(fmt, args);
|
|
va_end(args);
|
|
return r;
|
|
}
|
|
#endif
|
|
va_start(args, fmt);
|
|
r = vprintk(fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
|
|
/* cpu currently holding logbuf_lock */
|
|
static volatile unsigned int printk_cpu = UINT_MAX;
|
|
|
|
/*
|
|
* 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(unsigned int cpu)
|
|
{
|
|
return cpu_online(cpu) || have_callable_console();
|
|
}
|
|
|
|
/*
|
|
* Try to get console ownership to actually show the kernel
|
|
* messages from a 'printk'. Return true (and with the
|
|
* console_lock held, and 'console_locked' set) if it
|
|
* is successful, false otherwise.
|
|
*
|
|
* This gets called with the 'logbuf_lock' spinlock held and
|
|
* interrupts disabled. It should return with 'lockbuf_lock'
|
|
* released but interrupts still disabled.
|
|
*/
|
|
static int console_trylock_for_printk(unsigned int cpu)
|
|
__releases(&logbuf_lock)
|
|
{
|
|
int retval = 0, wake = 0;
|
|
|
|
if (console_trylock()) {
|
|
retval = 1;
|
|
|
|
/*
|
|
* If we can't use the console, we need to release
|
|
* the console semaphore by hand to avoid flushing
|
|
* the buffer. We need to hold the console semaphore
|
|
* in order to do this test safely.
|
|
*/
|
|
if (!can_use_console(cpu)) {
|
|
console_locked = 0;
|
|
wake = 1;
|
|
retval = 0;
|
|
}
|
|
}
|
|
printk_cpu = UINT_MAX;
|
|
if (wake)
|
|
up(&console_sem);
|
|
raw_spin_unlock(&logbuf_lock);
|
|
return retval;
|
|
}
|
|
static const char recursion_bug_msg [] =
|
|
KERN_CRIT "BUG: recent printk recursion!\n";
|
|
static int recursion_bug;
|
|
static int new_text_line = 1;
|
|
static char printk_buf[1024];
|
|
|
|
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();
|
|
}
|
|
}
|
|
}
|
|
|
|
asmlinkage int vprintk(const char *fmt, va_list args)
|
|
{
|
|
int printed_len = 0;
|
|
int current_log_level = default_message_loglevel;
|
|
unsigned long flags;
|
|
int this_cpu;
|
|
char *p;
|
|
size_t plen;
|
|
char special;
|
|
|
|
boot_delay_msec();
|
|
printk_delay();
|
|
|
|
/* This stops the holder of console_sem just where we want him */
|
|
local_irq_save(flags);
|
|
this_cpu = smp_processor_id();
|
|
|
|
/*
|
|
* Ouch, printk recursed into itself!
|
|
*/
|
|
if (unlikely(printk_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 = 1;
|
|
goto out_restore_irqs;
|
|
}
|
|
zap_locks();
|
|
}
|
|
|
|
lockdep_off();
|
|
raw_spin_lock(&logbuf_lock);
|
|
printk_cpu = this_cpu;
|
|
|
|
if (recursion_bug) {
|
|
recursion_bug = 0;
|
|
strcpy(printk_buf, recursion_bug_msg);
|
|
printed_len = strlen(recursion_bug_msg);
|
|
}
|
|
/* Emit the output into the temporary buffer */
|
|
printed_len += vscnprintf(printk_buf + printed_len,
|
|
sizeof(printk_buf) - printed_len, fmt, args);
|
|
|
|
p = printk_buf;
|
|
|
|
/* Read log level and handle special printk prefix */
|
|
plen = log_prefix(p, ¤t_log_level, &special);
|
|
if (plen) {
|
|
p += plen;
|
|
|
|
switch (special) {
|
|
case 'c': /* Strip <c> KERN_CONT, continue line */
|
|
plen = 0;
|
|
break;
|
|
case 'd': /* Strip <d> KERN_DEFAULT, start new line */
|
|
plen = 0;
|
|
default:
|
|
if (!new_text_line) {
|
|
emit_log_char('\n');
|
|
new_text_line = 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Copy the output into log_buf. If the caller didn't provide
|
|
* the appropriate log prefix, we insert them here
|
|
*/
|
|
for (; *p; p++) {
|
|
if (new_text_line) {
|
|
new_text_line = 0;
|
|
|
|
if (plen) {
|
|
/* Copy original log prefix */
|
|
int i;
|
|
|
|
for (i = 0; i < plen; i++)
|
|
emit_log_char(printk_buf[i]);
|
|
printed_len += plen;
|
|
} else {
|
|
/* Add log prefix */
|
|
emit_log_char('<');
|
|
emit_log_char(current_log_level + '0');
|
|
emit_log_char('>');
|
|
printed_len += 3;
|
|
}
|
|
|
|
if (printk_time) {
|
|
/* Add the current time stamp */
|
|
char tbuf[50], *tp;
|
|
unsigned tlen;
|
|
unsigned long long t;
|
|
unsigned long nanosec_rem;
|
|
|
|
t = cpu_clock(printk_cpu);
|
|
nanosec_rem = do_div(t, 1000000000);
|
|
tlen = sprintf(tbuf, "[%5lu.%06lu] ",
|
|
(unsigned long) t,
|
|
nanosec_rem / 1000);
|
|
|
|
for (tp = tbuf; tp < tbuf + tlen; tp++)
|
|
emit_log_char(*tp);
|
|
printed_len += tlen;
|
|
}
|
|
|
|
if (!*p)
|
|
break;
|
|
}
|
|
|
|
emit_log_char(*p);
|
|
if (*p == '\n')
|
|
new_text_line = 1;
|
|
}
|
|
|
|
/*
|
|
* Try to acquire and then immediately release the
|
|
* console semaphore. The release will do all the
|
|
* actual magic (print out buffers, wake up klogd,
|
|
* etc).
|
|
*
|
|
* The console_trylock_for_printk() function
|
|
* will release 'logbuf_lock' regardless of whether it
|
|
* actually gets the semaphore or not.
|
|
*/
|
|
if (console_trylock_for_printk(this_cpu))
|
|
console_unlock();
|
|
|
|
lockdep_on();
|
|
out_restore_irqs:
|
|
local_irq_restore(flags);
|
|
|
|
return printed_len;
|
|
}
|
|
EXPORT_SYMBOL(printk);
|
|
EXPORT_SYMBOL(vprintk);
|
|
|
|
#else
|
|
|
|
static void call_console_drivers(unsigned start, unsigned end)
|
|
{
|
|
}
|
|
|
|
#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; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
|
|
if (strcmp(console_cmdline[i].name, name) == 0 &&
|
|
console_cmdline[i].index == idx) {
|
|
if (!brl_options)
|
|
selected_console = i;
|
|
return 0;
|
|
}
|
|
if (i == MAX_CMDLINECONSOLES)
|
|
return -E2BIG;
|
|
if (!brl_options)
|
|
selected_console = i;
|
|
c = &console_cmdline[i];
|
|
strlcpy(c->name, name, sizeof(c->name));
|
|
c->options = options;
|
|
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
|
|
c->brl_options = brl_options;
|
|
#endif
|
|
c->index = idx;
|
|
return 0;
|
|
}
|
|
/*
|
|
* Set up a list of consoles. Called from init/main.c
|
|
*/
|
|
static int __init console_setup(char *str)
|
|
{
|
|
char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
|
|
char *s, *options, *brl_options = NULL;
|
|
int idx;
|
|
|
|
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
|
|
if (!memcmp(str, "brl,", 4)) {
|
|
brl_options = "";
|
|
str += 4;
|
|
} else if (!memcmp(str, "brl=", 4)) {
|
|
brl_options = str + 4;
|
|
str = strchr(brl_options, ',');
|
|
if (!str) {
|
|
printk(KERN_ERR "need port name after brl=\n");
|
|
return 1;
|
|
}
|
|
*(str++) = 0;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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;
|
|
if ((options = strchr(str, ',')) != NULL)
|
|
*(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 ((*s >= '0' && *s <= '9') || *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);
|
|
}
|
|
|
|
int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
|
|
{
|
|
struct console_cmdline *c;
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
|
|
if (strcmp(console_cmdline[i].name, name) == 0 &&
|
|
console_cmdline[i].index == idx) {
|
|
c = &console_cmdline[i];
|
|
strlcpy(c->name, name_new, sizeof(c->name));
|
|
c->name[sizeof(c->name) - 1] = 0;
|
|
c->options = options;
|
|
c->index = idx_new;
|
|
return i;
|
|
}
|
|
/* not found */
|
|
return -1;
|
|
}
|
|
|
|
int console_suspend_enabled = 1;
|
|
EXPORT_SYMBOL(console_suspend_enabled);
|
|
|
|
static int __init console_suspend_disable(char *str)
|
|
{
|
|
console_suspend_enabled = 0;
|
|
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 __cpuinit console_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
switch (action) {
|
|
case CPU_ONLINE:
|
|
case CPU_DEAD:
|
|
case CPU_DYING:
|
|
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)
|
|
{
|
|
BUG_ON(in_interrupt());
|
|
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.
|
|
*
|
|
* Tried to acquire a lock which guarantees that the caller has
|
|
* exclusive access to the console system and the console_drivers list.
|
|
*
|
|
* returns 1 on success, and 0 on failure to acquire the lock.
|
|
*/
|
|
int console_trylock(void)
|
|
{
|
|
if (down_trylock(&console_sem))
|
|
return 0;
|
|
if (console_suspended) {
|
|
up(&console_sem);
|
|
return 0;
|
|
}
|
|
console_locked = 1;
|
|
console_may_schedule = 0;
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(console_trylock);
|
|
|
|
int is_console_locked(void)
|
|
{
|
|
return console_locked;
|
|
}
|
|
|
|
static DEFINE_PER_CPU(int, printk_pending);
|
|
|
|
void printk_tick(void)
|
|
{
|
|
if (__this_cpu_read(printk_pending)) {
|
|
__this_cpu_write(printk_pending, 0);
|
|
wake_up_interruptible(&log_wait);
|
|
}
|
|
}
|
|
|
|
int printk_needs_cpu(int cpu)
|
|
{
|
|
if (cpu_is_offline(cpu))
|
|
printk_tick();
|
|
return __this_cpu_read(printk_pending);
|
|
}
|
|
|
|
void wake_up_klogd(void)
|
|
{
|
|
if (waitqueue_active(&log_wait))
|
|
this_cpu_write(printk_pending, 1);
|
|
}
|
|
|
|
/**
|
|
* 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 for klogd, we wake it up.
|
|
*
|
|
* console_unlock(); may be called from any context.
|
|
*/
|
|
void console_unlock(void)
|
|
{
|
|
unsigned long flags;
|
|
unsigned _con_start, _log_end;
|
|
unsigned wake_klogd = 0, retry = 0;
|
|
|
|
if (console_suspended) {
|
|
up(&console_sem);
|
|
return;
|
|
}
|
|
|
|
console_may_schedule = 0;
|
|
|
|
again:
|
|
for ( ; ; ) {
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
wake_klogd |= log_start - log_end;
|
|
if (con_start == log_end)
|
|
break; /* Nothing to print */
|
|
_con_start = con_start;
|
|
_log_end = log_end;
|
|
con_start = log_end; /* Flush */
|
|
raw_spin_unlock(&logbuf_lock);
|
|
stop_critical_timings(); /* don't trace print latency */
|
|
call_console_drivers(_con_start, _log_end);
|
|
start_critical_timings();
|
|
local_irq_restore(flags);
|
|
}
|
|
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);
|
|
if (con_start != log_end)
|
|
retry = 1;
|
|
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();
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
printk(KERN_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;
|
|
|
|
/*
|
|
* 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)) {
|
|
printk(KERN_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;
|
|
|
|
if (newcon->early_setup)
|
|
newcon->early_setup();
|
|
|
|
/*
|
|
* 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; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
|
|
i++) {
|
|
if (strcmp(console_cmdline[i].name, newcon->name) != 0)
|
|
continue;
|
|
if (newcon->index >= 0 &&
|
|
newcon->index != console_cmdline[i].index)
|
|
continue;
|
|
if (newcon->index < 0)
|
|
newcon->index = console_cmdline[i].index;
|
|
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
|
|
if (console_cmdline[i].brl_options) {
|
|
newcon->flags |= CON_BRL;
|
|
braille_register_console(newcon,
|
|
console_cmdline[i].index,
|
|
console_cmdline[i].options,
|
|
console_cmdline[i].brl_options);
|
|
return;
|
|
}
|
|
#endif
|
|
if (newcon->setup &&
|
|
newcon->setup(newcon, console_cmdline[i].options) != 0)
|
|
break;
|
|
newcon->flags |= CON_ENABLED;
|
|
newcon->index = console_cmdline[i].index;
|
|
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_PRINTBUFFER) {
|
|
/*
|
|
* console_unlock(); will print out the buffered messages
|
|
* for us.
|
|
*/
|
|
raw_spin_lock_irqsave(&logbuf_lock, flags);
|
|
con_start = log_start;
|
|
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)
|
|
*/
|
|
if (bcon &&
|
|
((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
|
|
!keep_bootcon) {
|
|
/* we need to iterate through twice, to make sure we print
|
|
* everything out, before we unregister the console(s)
|
|
*/
|
|
printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
|
|
newcon->name, newcon->index);
|
|
for_each_console(bcon)
|
|
if (bcon->flags & CON_BOOT)
|
|
unregister_console(bcon);
|
|
} else {
|
|
printk(KERN_INFO "%sconsole [%s%d] enabled\n",
|
|
(newcon->flags & CON_BOOT) ? "boot" : "" ,
|
|
newcon->name, newcon->index);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(register_console);
|
|
|
|
int unregister_console(struct console *console)
|
|
{
|
|
struct console *a, *b;
|
|
int res = 1;
|
|
|
|
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
|
|
if (console->flags & CON_BRL)
|
|
return braille_unregister_console(console);
|
|
#endif
|
|
|
|
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 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_unlock();
|
|
console_sysfs_notify();
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(unregister_console);
|
|
|
|
static int __init printk_late_init(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for_each_console(con) {
|
|
if (!keep_bootcon && con->flags & CON_BOOT) {
|
|
printk(KERN_INFO "turn off boot console %s%d\n",
|
|
con->name, con->index);
|
|
unregister_console(con);
|
|
}
|
|
}
|
|
hotcpu_notifier(console_cpu_notify, 0);
|
|
return 0;
|
|
}
|
|
late_initcall(printk_late_init);
|
|
|
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#if defined CONFIG_PRINTK
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/*
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* printk rate limiting, lifted from the networking subsystem.
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*
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* This enforces a rate limit: not more than 10 kernel messages
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* every 5s to make a denial-of-service attack impossible.
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*/
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DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
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int __printk_ratelimit(const char *func)
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{
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return ___ratelimit(&printk_ratelimit_state, func);
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}
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EXPORT_SYMBOL(__printk_ratelimit);
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/**
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* printk_timed_ratelimit - caller-controlled printk ratelimiting
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* @caller_jiffies: pointer to caller's state
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* @interval_msecs: minimum interval between prints
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*
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* printk_timed_ratelimit() returns true if more than @interval_msecs
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* milliseconds have elapsed since the last time printk_timed_ratelimit()
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* returned true.
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*/
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bool printk_timed_ratelimit(unsigned long *caller_jiffies,
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unsigned int interval_msecs)
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{
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if (*caller_jiffies == 0
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|| !time_in_range(jiffies, *caller_jiffies,
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*caller_jiffies
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+ msecs_to_jiffies(interval_msecs))) {
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*caller_jiffies = jiffies;
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return true;
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}
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return false;
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}
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EXPORT_SYMBOL(printk_timed_ratelimit);
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static DEFINE_SPINLOCK(dump_list_lock);
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static LIST_HEAD(dump_list);
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/**
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* kmsg_dump_register - register a kernel log dumper.
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* @dumper: pointer to the kmsg_dumper structure
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*
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* Adds a kernel log dumper to the system. The dump callback in the
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* structure will be called when the kernel oopses or panics and must be
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* set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
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*/
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int kmsg_dump_register(struct kmsg_dumper *dumper)
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{
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unsigned long flags;
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int err = -EBUSY;
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/* The dump callback needs to be set */
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if (!dumper->dump)
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return -EINVAL;
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spin_lock_irqsave(&dump_list_lock, flags);
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/* Don't allow registering multiple times */
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if (!dumper->registered) {
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dumper->registered = 1;
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list_add_tail_rcu(&dumper->list, &dump_list);
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err = 0;
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}
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spin_unlock_irqrestore(&dump_list_lock, flags);
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return err;
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}
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EXPORT_SYMBOL_GPL(kmsg_dump_register);
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/**
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* kmsg_dump_unregister - unregister a kmsg dumper.
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* @dumper: pointer to the kmsg_dumper structure
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*
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* Removes a dump device from the system. Returns zero on success and
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* %-EINVAL otherwise.
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*/
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int kmsg_dump_unregister(struct kmsg_dumper *dumper)
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{
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unsigned long flags;
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int err = -EINVAL;
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spin_lock_irqsave(&dump_list_lock, flags);
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if (dumper->registered) {
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dumper->registered = 0;
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list_del_rcu(&dumper->list);
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err = 0;
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}
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spin_unlock_irqrestore(&dump_list_lock, flags);
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synchronize_rcu();
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return err;
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}
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EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
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/**
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* kmsg_dump - dump kernel log to kernel message dumpers.
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* @reason: the reason (oops, panic etc) for dumping
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*
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* Iterate through each of the dump devices and call the oops/panic
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* callbacks with the log buffer.
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*/
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void kmsg_dump(enum kmsg_dump_reason reason)
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{
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unsigned long end;
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unsigned chars;
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struct kmsg_dumper *dumper;
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const char *s1, *s2;
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unsigned long l1, l2;
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unsigned long flags;
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/* Theoretically, the log could move on after we do this, but
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there's not a lot we can do about that. The new messages
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will overwrite the start of what we dump. */
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raw_spin_lock_irqsave(&logbuf_lock, flags);
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end = log_end & LOG_BUF_MASK;
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chars = logged_chars;
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raw_spin_unlock_irqrestore(&logbuf_lock, flags);
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if (chars > end) {
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s1 = log_buf + log_buf_len - chars + end;
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l1 = chars - end;
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s2 = log_buf;
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l2 = end;
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} else {
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s1 = "";
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l1 = 0;
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s2 = log_buf + end - chars;
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l2 = chars;
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}
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rcu_read_lock();
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list_for_each_entry_rcu(dumper, &dump_list, list)
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dumper->dump(dumper, reason, s1, l1, s2, l2);
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rcu_read_unlock();
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}
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#endif
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