diff options
Diffstat (limited to 'xenolinux-2.4.25-sparse/kernel/printk.c')
| -rw-r--r-- | xenolinux-2.4.25-sparse/kernel/printk.c | 703 |
1 files changed, 703 insertions, 0 deletions
diff --git a/xenolinux-2.4.25-sparse/kernel/printk.c b/xenolinux-2.4.25-sparse/kernel/printk.c new file mode 100644 index 0000000000..6cfedd9c02 --- /dev/null +++ b/xenolinux-2.4.25-sparse/kernel/printk.c @@ -0,0 +1,703 @@ +/* + * linux/kernel/printk.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * Modified to make sys_syslog() more flexible: added commands to + * return the last 4k of kernel messages, regardless of whether + * they've been read or not. Added option to suppress kernel printk's + * to the console. Added hook for sending the console messages + * elsewhere, in preparation for a serial line console (someday). + * Ted Ts'o, 2/11/93. + * Modified for sysctl support, 1/8/97, Chris Horn. + * Fixed SMP synchronization, 08/08/99, Manfred Spraul + * manfreds@colorfullife.com + * Rewrote bits to get rid of console_lock + * 01Mar01 Andrew Morton <andrewm@uow.edu.au> + */ + +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/tty.h> +#include <linux/tty_driver.h> +#include <linux/smp_lock.h> +#include <linux/console.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/interrupt.h> /* For in_interrupt() */ +#include <linux/config.h> + +#include <asm/uaccess.h> + +#if !defined(CONFIG_LOG_BUF_SHIFT) || (CONFIG_LOG_BUF_SHIFT == 0) +#if defined(CONFIG_MULTIQUAD) || defined(CONFIG_IA64) +#define LOG_BUF_LEN (65536) +#elif defined(CONFIG_ARCH_S390) +#define LOG_BUF_LEN (131072) +#elif defined(CONFIG_SMP) +#define LOG_BUF_LEN (32768) +#else +#define LOG_BUF_LEN (16384) /* This must be a power of two */ +#endif +#else /* CONFIG_LOG_BUF_SHIFT */ +#define LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) +#endif + +#define LOG_BUF_MASK (LOG_BUF_LEN-1) + +#ifndef arch_consoles_callable +#define arch_consoles_callable() (1) +#endif + +/* printk's without a loglevel use this.. */ +#define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ + +/* We show everything that is MORE important than this.. */ +#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ +#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ + +DECLARE_WAIT_QUEUE_HEAD(log_wait); + +int console_printk[4] = { + DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ + DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ + MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ + DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ +}; + +int oops_in_progress; + +/* + * console_sem protects the console_drivers list, and also + * provides serialisation for access to the entire console + * driver system. + */ +static DECLARE_MUTEX(console_sem); +struct console *console_drivers; + +/* + * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars + * It is also used in interesting ways to provide interlocking in + * release_console_sem(). + */ +static spinlock_t logbuf_lock = SPIN_LOCK_UNLOCKED; + +static char log_buf[LOG_BUF_LEN]; +#define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) + +/* + * The indices into log_buf are not constrained to LOG_BUF_LEN - they + * must be masked before subscripting + */ +static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */ +static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */ +static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */ +static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ + +struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; +static int preferred_console = -1; + +/* Flag: console code may call schedule() */ +static int console_may_schedule; + +/* + * Setup a list of consoles. Called from init/main.c + */ +static int __init console_setup(char *str) +{ + struct console_cmdline *c; + char name[sizeof(c->name)]; + char *s, *options; + int i, idx; + + /* + * Decode str into name, index, options. + */ + if (str[0] >= '0' && str[0] <= '9') { + strcpy(name, "ttyS"); + strncpy(name + 4, str, sizeof(name) - 5); + } else + strncpy(name, str, sizeof(name) - 1); + name[sizeof(name) - 1] = 0; + if ((options = strchr(str, ',')) != NULL) + *(options++) = 0; +#ifdef __sparc__ + if (!strcmp(str, "ttya")) + strcpy(name, "ttyS0"); + if (!strcmp(str, "ttyb")) + strcpy(name, "ttyS1"); +#endif + for(s = name; *s; s++) + if (*s >= '0' && *s <= '9') + break; + idx = simple_strtoul(s, NULL, 10); + *s = 0; + + /* + * 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) { + preferred_console = i; + return 1; + } + if (i == MAX_CMDLINECONSOLES) + return 1; + preferred_console = i; + c = &console_cmdline[i]; + memcpy(c->name, name, sizeof(c->name)); + c->options = options; + c->index = idx; + return 1; +} + +__setup("console=", console_setup); + +/* + * Commands to do_syslog: + * + * 0 -- Close the log. Currently a NOP. + * 1 -- Open the log. Currently a NOP. + * 2 -- Read from the log. + * 3 -- Read all messages remaining in the ring buffer. + * 4 -- Read and clear all messages remaining in the ring buffer + * 5 -- Clear ring buffer. + * 6 -- Disable printk's to console + * 7 -- Enable printk's to console + * 8 -- Set level of messages printed to console + * 9 -- Return number of unread characters in the log buffer + */ +int do_syslog(int type, char * buf, int len) +{ + unsigned long i, j, limit, count; + int do_clear = 0; + char c; + int error = 0; + + switch (type) { + case 0: /* Close log */ + break; + case 1: /* Open log */ + break; + case 2: /* Read from log */ + error = -EINVAL; + if (!buf || len < 0) + goto out; + error = 0; + if (!len) + goto out; + error = verify_area(VERIFY_WRITE,buf,len); + if (error) + goto out; + error = wait_event_interruptible(log_wait, (log_start - log_end)); + if (error) + goto out; + i = 0; + spin_lock_irq(&logbuf_lock); + while ((log_start != log_end) && i < len) { + c = LOG_BUF(log_start); + log_start++; + spin_unlock_irq(&logbuf_lock); + __put_user(c,buf); + buf++; + i++; + spin_lock_irq(&logbuf_lock); + } + spin_unlock_irq(&logbuf_lock); + error = i; + break; + case 4: /* Read/clear last kernel messages */ + do_clear = 1; + /* FALL THRU */ + case 3: /* Read last kernel messages */ + error = -EINVAL; + if (!buf || len < 0) + goto out; + error = 0; + if (!len) + goto out; + error = verify_area(VERIFY_WRITE,buf,len); + if (error) + goto out; + count = len; + if (count > LOG_BUF_LEN) + count = LOG_BUF_LEN; + spin_lock_irq(&logbuf_lock); + if (count > logged_chars) + count = logged_chars; + if (do_clear) + logged_chars = 0; + limit = log_end; + /* + * __put_user() could sleep, and while we sleep + * printk() could overwrite the messages + * we try to copy to user space. Therefore + * the messages are copied in reverse. <manfreds> + */ + for(i=0;i < count;i++) { + j = limit-1-i; + if (j+LOG_BUF_LEN < log_end) + break; + c = LOG_BUF(j); + spin_unlock_irq(&logbuf_lock); + __put_user(c,&buf[count-1-i]); + spin_lock_irq(&logbuf_lock); + } + spin_unlock_irq(&logbuf_lock); + error = i; + if(i != count) { + int offset = count-error; + /* buffer overflow during copy, correct user buffer. */ + for(i=0;i<error;i++) { + __get_user(c,&buf[i+offset]); + __put_user(c,&buf[i]); + } + } + + break; + case 5: /* Clear ring buffer */ + spin_lock_irq(&logbuf_lock); + logged_chars = 0; + spin_unlock_irq(&logbuf_lock); + break; + case 6: /* Disable logging to console */ + spin_lock_irq(&logbuf_lock); + console_loglevel = minimum_console_loglevel; + spin_unlock_irq(&logbuf_lock); + break; + case 7: /* Enable logging to console */ + spin_lock_irq(&logbuf_lock); + console_loglevel = default_console_loglevel; + spin_unlock_irq(&logbuf_lock); + break; + case 8: /* Set level of messages printed to console */ + error = -EINVAL; + if (len < 1 || len > 8) + goto out; + if (len < minimum_console_loglevel) + len = minimum_console_loglevel; + spin_lock_irq(&logbuf_lock); + console_loglevel = len; + spin_unlock_irq(&logbuf_lock); + error = 0; + break; + case 9: /* Number of chars in the log buffer */ + spin_lock_irq(&logbuf_lock); + error = log_end - log_start; + spin_unlock_irq(&logbuf_lock); + break; + default: + error = -EINVAL; + break; + } +out: + return error; +} + +asmlinkage long sys_syslog(int type, char * buf, int len) +{ + if ((type != 3) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + return do_syslog(type, buf, len); +} + +/* + * Call the console drivers on a range of log_buf + */ +static void __call_console_drivers(unsigned long start, unsigned long end) +{ + struct console *con; + + for (con = console_drivers; con; con = con->next) { + if ((con->flags & CON_ENABLED) && con->write) + con->write(con, &LOG_BUF(start), end - start); + } +} + +/* + * Write out chars from start to end - 1 inclusive + */ +static void _call_console_drivers(unsigned long start, unsigned long end, int msg_log_level) +{ + if (msg_log_level < console_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); + } + } +} + +/* + * Call the console drivers, asking them to write out + * log_buf[start] to log_buf[end - 1]. + * The console_sem must be held. + */ +static void call_console_drivers(unsigned long start, unsigned long end) +{ + unsigned long cur_index, start_print; + static int msg_level = -1; + + if (((long)(start - end)) > 0) + BUG(); + + cur_index = start; + start_print = start; + while (cur_index != end) { + if ( msg_level < 0 && + ((end - cur_index) > 2) && + LOG_BUF(cur_index + 0) == '<' && + LOG_BUF(cur_index + 1) >= '0' && + LOG_BUF(cur_index + 1) <= '7' && + LOG_BUF(cur_index + 2) == '>') + { + msg_level = LOG_BUF(cur_index + 1) - '0'; + cur_index += 3; + 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++; +} + +/* + * This is printk. It can be called from any context. We want it to work. + * + * We try to grab the console_sem. 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 release_console_sem() and will send it to the + * consoles before releasing the semaphore. + * + * 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. + */ +asmlinkage int printk(const char *fmt, ...) +{ + va_list args; + unsigned long flags; + int printed_len; + char *p; + static char printk_buf[1024]; + static int log_level_unknown = 1; + + if (oops_in_progress) { + /* If a crash is occurring, make sure we can't deadlock */ + spin_lock_init(&logbuf_lock); + /* And make sure that we print immediately */ + init_MUTEX(&console_sem); + } + + /* This stops the holder of console_sem just where we want him */ + spin_lock_irqsave(&logbuf_lock, flags); + + /* Emit the output into the temporary buffer */ + va_start(args, fmt); + printed_len = vsnprintf(printk_buf, sizeof(printk_buf), fmt, args); + va_end(args); + +#if 0 + /* Useful if things are going wrong very early in the day. */ + (void)HYPERVISOR_console_write(printk_buf, printed_len); +#endif + + /* + * Copy the output into log_buf. If the caller didn't provide + * appropriate log level tags, we insert them here + */ + for (p = printk_buf; *p; p++) { + if (log_level_unknown) { + if (p[0] != '<' || p[1] < '0' || p[1] > '7' || p[2] != '>') { + emit_log_char('<'); + emit_log_char(default_message_loglevel + '0'); + emit_log_char('>'); + } + log_level_unknown = 0; + } + emit_log_char(*p); + if (*p == '\n') + log_level_unknown = 1; + } + + if (!arch_consoles_callable()) { + /* + * On some architectures, the consoles are not usable + * on secondary CPUs early in the boot process. + */ + spin_unlock_irqrestore(&logbuf_lock, flags); + goto out; + } + if (!down_trylock(&console_sem)) { + /* + * We own the drivers. We can drop the spinlock and let + * release_console_sem() print the text + */ + spin_unlock_irqrestore(&logbuf_lock, flags); + console_may_schedule = 0; + release_console_sem(); + } else { + /* + * Someone else owns the drivers. We drop the spinlock, which + * allows the semaphore holder to proceed and to call the + * console drivers with the output which we just produced. + */ + spin_unlock_irqrestore(&logbuf_lock, flags); + } +out: + return printed_len; +} +EXPORT_SYMBOL(printk); + +/** + * acquire_console_sem - lock the console system for exclusive use. + * + * Acquires a semaphore which guarantees that the caller has + * exclusive access to the console system and the console_drivers list. + * + * Can sleep, returns nothing. + */ +void acquire_console_sem(void) +{ + if (in_interrupt()) + BUG(); + down(&console_sem); + console_may_schedule = 1; +} +EXPORT_SYMBOL(acquire_console_sem); + +/** + * release_console_sem - unlock the console system + * + * Releases the semaphore which the caller holds on the console system + * and the console driver list. + * + * While the semaphore was held, console output may have been buffered + * by printk(). If this is the case, release_console_sem() emits + * the output prior to releasing the semaphore. + * + * If there is output waiting for klogd, we wake it up. + * + * release_console_sem() may be called from any context. + */ +void release_console_sem(void) +{ + unsigned long flags; + unsigned long _con_start, _log_end; + unsigned long must_wake_klogd = 0; + + for ( ; ; ) { + spin_lock_irqsave(&logbuf_lock, flags); + must_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 */ + spin_unlock_irqrestore(&logbuf_lock, flags); + call_console_drivers(_con_start, _log_end); + } + console_may_schedule = 0; + up(&console_sem); + spin_unlock_irqrestore(&logbuf_lock, flags); + if (must_wake_klogd && !oops_in_progress) + wake_up_interruptible(&log_wait); +} + +/** 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 acquire_console_sem(). + */ +void console_conditional_schedule(void) +{ + if (console_may_schedule && current->need_resched) { + set_current_state(TASK_RUNNING); + schedule(); + } +} + +void console_print(const char *s) +{ + printk(KERN_EMERG "%s", s); +} +EXPORT_SYMBOL(console_print); + +void console_unblank(void) +{ + struct console *c; + + /* + * Try to get the console semaphore. If someone else owns it + * we have to return without unblanking because console_unblank + * may be called in interrupt context. + */ + if (down_trylock(&console_sem) != 0) + return; + console_may_schedule = 0; + for (c = console_drivers; c != NULL; c = c->next) + if ((c->flags & CON_ENABLED) && c->unblank) + c->unblank(); + release_console_sem(); +} +EXPORT_SYMBOL(console_unblank); + +/* + * 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. + */ +void register_console(struct console * console) +{ + int i; + unsigned long flags; + + /* + * 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 (console->index < 0) + console->index = 0; + if (console->setup == NULL || + console->setup(console, NULL) == 0) { + console->flags |= CON_ENABLED | 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, console->name) != 0) + continue; + if (console->index >= 0 && + console->index != console_cmdline[i].index) + continue; + if (console->index < 0) + console->index = console_cmdline[i].index; + if (console->setup && + console->setup(console, console_cmdline[i].options) != 0) + break; + console->flags |= CON_ENABLED; + console->index = console_cmdline[i].index; + if (i == preferred_console) + console->flags |= CON_CONSDEV; + break; + } + + if (!(console->flags & CON_ENABLED)) + return; + + /* + * Put this console in the list - keep the + * preferred driver at the head of the list. + */ + acquire_console_sem(); + if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { + console->next = console_drivers; + console_drivers = console; + } else { + console->next = console_drivers->next; + console_drivers->next = console; + } + if (console->flags & CON_PRINTBUFFER) { + /* + * release_console_sem() will print out the buffered messages for us. + */ + spin_lock_irqsave(&logbuf_lock, flags); + con_start = log_start; + spin_unlock_irqrestore(&logbuf_lock, flags); + } + release_console_sem(); +} +EXPORT_SYMBOL(register_console); + +int unregister_console(struct console * console) +{ + struct console *a,*b; + int res = 1; + + acquire_console_sem(); + if (console_drivers == console) { + console_drivers=console->next; + res = 0; + } else { + 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 last console is removed, we re-enable picking the first + * one that gets registered. Without that, pmac early boot console + * would prevent fbcon from taking over. + */ + if (console_drivers == NULL) + preferred_console = -1; + + + release_console_sem(); + return res; +} +EXPORT_SYMBOL(unregister_console); + +/** + * tty_write_message - write a message to a certain tty, not just the console. + * + * This is used for messages that need to be redirected to a specific tty. + * We don't put it into the syslog queue right now maybe in the future if + * really needed. + */ +void tty_write_message(struct tty_struct *tty, char *msg) +{ + if (tty && tty->driver.write) + tty->driver.write(tty, 0, msg, strlen(msg)); + return; +} |