#include <linux/bootmem.h>
#include <linux/syscalls.h>
#include <linux/kexec.h>
+#include <linux/kdb.h>
#include <linux/ratelimit.h>
+#include <linux/kmsg_dump.h>
+#include <linux/syslog.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/rculist.h>
#include <asm/uaccess.h>
/*
- * for_each_console() allows you to iterate on each console
- */
-#define for_each_console(con) \
- for (con = console_drivers; con != NULL; con = con->next)
-
-/*
* Architectures can override it:
*/
void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
};
-static int saved_console_loglevel = -1;
-
/*
* Low level drivers may need that to know if they can schedule in
* their unblank() callback or not. So let's export it.
* provides serialisation for access to the entire console
* driver system.
*/
-static DECLARE_MUTEX(console_sem);
+static DEFINE_SEMAPHORE(console_sem);
struct console *console_drivers;
EXPORT_SYMBOL_GPL(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().
+ * console_unlock();.
*/
static DEFINE_SPINLOCK(logbuf_lock);
static char *log_buf = __log_buf;
static int log_buf_len = __LOG_BUF_LEN;
static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
+static int saved_console_loglevel = -1;
#ifdef CONFIG_KEXEC
/*
#ifdef CONFIG_BOOT_PRINTK_DELAY
-static unsigned int boot_delay; /* msecs delay after each printk during bootup */
+static int boot_delay; /* msecs delay after each printk during bootup */
static unsigned long long loops_per_msec; /* based on boot_delay */
static int __init boot_delay_setup(char *str)
}
#endif
-/*
- * 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
- * 10 -- Return size of the log buffer
- */
-int do_syslog(int type, char __user *buf, int len)
+#ifdef CONFIG_SECURITY_DMESG_RESTRICT
+int dmesg_restrict = 1;
+#else
+int dmesg_restrict;
+#endif
+
+static int syslog_action_restricted(int type)
+{
+ if (dmesg_restrict)
+ return 1;
+ /* Unless restricted, we allow "read all" and "get buffer size" for everybody */
+ return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER;
+}
+
+static int check_syslog_permissions(int type, bool from_file)
+{
+ /*
+ * If this is from /proc/kmsg and we've already opened it, then we've
+ * already done the capabilities checks at open time.
+ */
+ if (from_file && type != SYSLOG_ACTION_OPEN)
+ return 0;
+
+ if (syslog_action_restricted(type)) {
+ if (capable(CAP_SYSLOG))
+ return 0;
+ /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
+ if (capable(CAP_SYS_ADMIN)) {
+ WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN "
+ "but no CAP_SYSLOG (deprecated).\n");
+ return 0;
+ }
+ return -EPERM;
+ }
+ return 0;
+}
+
+int do_syslog(int type, char __user *buf, int len, bool from_file)
{
unsigned i, j, limit, count;
int do_clear = 0;
char c;
- int error = 0;
+ int error;
+
+ error = check_syslog_permissions(type, from_file);
+ if (error)
+ goto out;
error = security_syslog(type);
if (error)
return error;
switch (type) {
- case 0: /* Close log */
+ case SYSLOG_ACTION_CLOSE: /* Close log */
break;
- case 1: /* Open log */
+ case SYSLOG_ACTION_OPEN: /* Open log */
break;
- case 2: /* Read from log */
+ case SYSLOG_ACTION_READ: /* Read from log */
error = -EINVAL;
if (!buf || len < 0)
goto out;
if (!error)
error = i;
break;
- case 4: /* Read/clear last kernel messages */
+ /* Read/clear last kernel messages */
+ case SYSLOG_ACTION_READ_CLEAR:
do_clear = 1;
/* FALL THRU */
- case 3: /* Read last kernel messages */
+ /* Read last kernel messages */
+ case SYSLOG_ACTION_READ_ALL:
error = -EINVAL;
if (!buf || len < 0)
goto out;
}
}
break;
- case 5: /* Clear ring buffer */
+ /* Clear ring buffer */
+ case SYSLOG_ACTION_CLEAR:
logged_chars = 0;
break;
- case 6: /* Disable logging to console */
+ /* Disable logging to console */
+ case SYSLOG_ACTION_CONSOLE_OFF:
if (saved_console_loglevel == -1)
saved_console_loglevel = console_loglevel;
console_loglevel = minimum_console_loglevel;
break;
- case 7: /* Enable logging to console */
+ /* Enable logging to console */
+ case SYSLOG_ACTION_CONSOLE_ON:
if (saved_console_loglevel != -1) {
console_loglevel = saved_console_loglevel;
saved_console_loglevel = -1;
}
break;
- case 8: /* Set level of messages printed to console */
+ /* Set level of messages printed to console */
+ case SYSLOG_ACTION_CONSOLE_LEVEL:
error = -EINVAL;
if (len < 1 || len > 8)
goto out;
saved_console_loglevel = -1;
error = 0;
break;
- case 9: /* Number of chars in the log buffer */
+ /* Number of chars in the log buffer */
+ case SYSLOG_ACTION_SIZE_UNREAD:
error = log_end - log_start;
break;
- case 10: /* Size of the log buffer */
+ /* Size of the log buffer */
+ case SYSLOG_ACTION_SIZE_BUFFER:
error = log_buf_len;
break;
default:
SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
{
- return do_syslog(type, buf, 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;
+ syslog_data[1] = log_buf + log_buf_len;
+ syslog_data[2] = log_buf + log_end -
+ (logged_chars < log_buf_len ? logged_chars : log_buf_len);
+ syslog_data[3] = log_buf + log_end;
+}
+#endif /* CONFIG_KGDB_KDB */
+
/*
* Call the console drivers on a range of log_buf
*/
/*
* Call the console drivers, asking them to write out
* log_buf[start] to log_buf[end - 1].
- * The console_sem must be held.
+ * The console_lock must be held.
*/
static void call_console_drivers(unsigned start, unsigned end)
{
/* 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);
+ sema_init(&console_sem, 1);
}
#if defined(CONFIG_PRINTK_TIME)
*
* 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
+ * 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 release_console_sem() and will send it to the
- * consoles before releasing the semaphore.
+ * 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
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);
/*
* Try to get console ownership to actually show the kernel
* messages from a 'printk'. Return true (and with the
- * console_semaphore held, and 'console_locked' set) if it
+ * 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 acquire_console_semaphore_for_printk(unsigned int cpu)
+static int console_trylock_for_printk(unsigned int cpu)
+ __releases(&logbuf_lock)
{
int retval = 0;
- if (!try_acquire_console_sem()) {
+ if (console_trylock()) {
retval = 1;
/*
* actual magic (print out buffers, wake up klogd,
* etc).
*
- * The acquire_console_semaphore_for_printk() function
+ * The console_trylock_for_printk() function
* will release 'logbuf_lock' regardless of whether it
* actually gets the semaphore or not.
*/
- if (acquire_console_semaphore_for_printk(this_cpu))
- release_console_sem();
+ if (console_trylock_for_printk(this_cpu))
+ console_unlock();
lockdep_on();
out_restore_irqs:
if (!console_suspend_enabled)
return;
printk("Suspending console(s) (use no_console_suspend to debug)\n");
- acquire_console_sem();
+ console_lock();
console_suspended = 1;
up(&console_sem);
}
return;
down(&console_sem);
console_suspended = 0;
- release_console_sem();
+ 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;
}
/**
- * acquire_console_sem - lock the console system for exclusive use.
+ * console_lock - lock the console system for exclusive use.
*
- * Acquires a semaphore which guarantees that the caller has
+ * 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 acquire_console_sem(void)
+void console_lock(void)
{
BUG_ON(in_interrupt());
down(&console_sem);
console_locked = 1;
console_may_schedule = 1;
}
-EXPORT_SYMBOL(acquire_console_sem);
+EXPORT_SYMBOL(console_lock);
-int try_acquire_console_sem(void)
+/**
+ * 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 -1;
+ return 0;
if (console_suspended) {
up(&console_sem);
- return -1;
+ return 0;
}
console_locked = 1;
console_may_schedule = 0;
- return 0;
+ return 1;
}
-EXPORT_SYMBOL(try_acquire_console_sem);
+EXPORT_SYMBOL(console_trylock);
int is_console_locked(void)
{
void printk_tick(void)
{
- if (__get_cpu_var(printk_pending)) {
- __get_cpu_var(printk_pending) = 0;
+ if (__this_cpu_read(printk_pending)) {
+ __this_cpu_write(printk_pending, 0);
wake_up_interruptible(&log_wait);
}
}
int printk_needs_cpu(int cpu)
{
- return per_cpu(printk_pending, cpu);
+ if (cpu_is_offline(cpu))
+ printk_tick();
+ return __this_cpu_read(printk_pending);
}
void wake_up_klogd(void)
{
if (waitqueue_active(&log_wait))
- __raw_get_cpu_var(printk_pending) = 1;
+ this_cpu_write(printk_pending, 1);
}
/**
- * release_console_sem - unlock the console system
+ * console_unlock - unlock the console system
*
- * Releases the semaphore which the caller holds on the console system
+ * Releases the console_lock 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.
+ * 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.
*
- * release_console_sem() may be called from any context.
+ * console_unlock(); may be called from any context.
*/
-void release_console_sem(void)
+void console_unlock(void)
{
unsigned long flags;
unsigned _con_start, _log_end;
if (wake_klogd)
wake_up_klogd();
}
-EXPORT_SYMBOL(release_console_sem);
+EXPORT_SYMBOL(console_unlock);
/**
* console_conditional_schedule - yield the CPU if required
* if this CPU should yield the CPU to another task, do
* so here.
*
- * Must be called within acquire_console_sem().
+ * Must be called within console_lock();.
*/
void __sched console_conditional_schedule(void)
{
if (down_trylock(&console_sem) != 0)
return;
} else
- acquire_console_sem();
+ console_lock();
console_locked = 1;
console_may_schedule = 0;
for_each_console(c)
if ((c->flags & CON_ENABLED) && c->unblank)
c->unblank();
- release_console_sem();
+ console_unlock();
}
/*
struct console *c;
struct tty_driver *driver = NULL;
- acquire_console_sem();
+ console_lock();
for_each_console(c) {
if (!c->device)
continue;
if (driver)
break;
}
- release_console_sem();
+ console_unlock();
return driver;
}
*/
void console_stop(struct console *console)
{
- acquire_console_sem();
+ console_lock();
console->flags &= ~CON_ENABLED;
- release_console_sem();
+ console_unlock();
}
EXPORT_SYMBOL(console_stop);
void console_start(struct console *console)
{
- acquire_console_sem();
+ console_lock();
console->flags |= CON_ENABLED;
- release_console_sem();
+ console_unlock();
}
EXPORT_SYMBOL(console_start);
* Put this console in the list - keep the
* preferred driver at the head of the list.
*/
- acquire_console_sem();
+ console_lock();
if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
newcon->next = console_drivers;
console_drivers = newcon;
}
if (newcon->flags & CON_PRINTBUFFER) {
/*
- * release_console_sem() will print out the buffered messages
+ * console_unlock(); 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();
+ console_unlock();
+ console_sysfs_notify();
/*
* By unregistering the bootconsoles after we enable the real console
return braille_unregister_console(console);
#endif
- acquire_console_sem();
+ console_lock();
if (console_drivers == console) {
console_drivers=console->next;
res = 0;
if (console_drivers != NULL && console->flags & CON_CONSDEV)
console_drivers->flags |= CON_CONSDEV;
- release_console_sem();
+ console_unlock();
+ console_sysfs_notify();
return res;
}
EXPORT_SYMBOL(unregister_console);
-static int __init disable_boot_consoles(void)
+static int __init printk_late_init(void)
{
struct console *con;
unregister_console(con);
}
}
+ hotcpu_notifier(console_cpu_notify, 0);
return 0;
}
-late_initcall(disable_boot_consoles);
+late_initcall(printk_late_init);
#if defined CONFIG_PRINTK
return false;
}
EXPORT_SYMBOL(printk_timed_ratelimit);
+
+static DEFINE_SPINLOCK(dump_list_lock);
+static LIST_HEAD(dump_list);
+
+/**
+ * kmsg_dump_register - register a kernel log dumper.
+ * @dumper: pointer to the kmsg_dumper structure
+ *
+ * Adds a kernel log dumper to the system. The dump callback in the
+ * structure will be called when the kernel oopses or panics and must be
+ * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
+ */
+int kmsg_dump_register(struct kmsg_dumper *dumper)
+{
+ unsigned long flags;
+ int err = -EBUSY;
+
+ /* The dump callback needs to be set */
+ if (!dumper->dump)
+ return -EINVAL;
+
+ spin_lock_irqsave(&dump_list_lock, flags);
+ /* Don't allow registering multiple times */
+ if (!dumper->registered) {
+ dumper->registered = 1;
+ list_add_tail_rcu(&dumper->list, &dump_list);
+ err = 0;
+ }
+ spin_unlock_irqrestore(&dump_list_lock, flags);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_register);
+
+/**
+ * kmsg_dump_unregister - unregister a kmsg dumper.
+ * @dumper: pointer to the kmsg_dumper structure
+ *
+ * Removes a dump device from the system. Returns zero on success and
+ * %-EINVAL otherwise.
+ */
+int kmsg_dump_unregister(struct kmsg_dumper *dumper)
+{
+ unsigned long flags;
+ int err = -EINVAL;
+
+ spin_lock_irqsave(&dump_list_lock, flags);
+ if (dumper->registered) {
+ dumper->registered = 0;
+ list_del_rcu(&dumper->list);
+ err = 0;
+ }
+ spin_unlock_irqrestore(&dump_list_lock, flags);
+ synchronize_rcu();
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
+
+/**
+ * kmsg_dump - dump kernel log to kernel message dumpers.
+ * @reason: the reason (oops, panic etc) for dumping
+ *
+ * Iterate through each of the dump devices and call the oops/panic
+ * callbacks with the log buffer.
+ */
+void kmsg_dump(enum kmsg_dump_reason reason)
+{
+ unsigned long end;
+ unsigned chars;
+ struct kmsg_dumper *dumper;
+ const char *s1, *s2;
+ unsigned long l1, l2;
+ unsigned long flags;
+
+ /* Theoretically, the log could move on after we do this, but
+ there's not a lot we can do about that. The new messages
+ will overwrite the start of what we dump. */
+ spin_lock_irqsave(&logbuf_lock, flags);
+ end = log_end & LOG_BUF_MASK;
+ chars = logged_chars;
+ spin_unlock_irqrestore(&logbuf_lock, flags);
+
+ if (chars > end) {
+ s1 = log_buf + log_buf_len - chars + end;
+ l1 = chars - end;
+
+ s2 = log_buf;
+ l2 = end;
+ } else {
+ s1 = "";
+ l1 = 0;
+
+ s2 = log_buf + end - chars;
+ l2 = chars;
+ }
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(dumper, &dump_list, list)
+ dumper->dump(dumper, reason, s1, l1, s2, l2);
+ rcu_read_unlock();
+}
#endif
projects / linux-flexiantxendom0-natty.git / blobdiff