1 files changed, 148 insertions, 34 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index f38b07f78a4e..75077ad0b537 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -33,6 +33,9 @@
 #include <linux/bootmem.h>
 #include <linux/syscalls.h>
 #include <linux/kexec.h>
+#include <linux/ratelimit.h>
+#include <linux/kmsg_dump.h>
+#include <linux/syslog.h>
 
 #include <asm/uaccess.h>
 
@@ -67,8 +70,6 @@ int console_printk[4] = {
 	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.
@@ -143,6 +144,7 @@ static char __log_buf[__LOG_BUF_LEN];
 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
 /*
@@ -256,38 +258,23 @@ static inline void boot_delay_msec(void)
 }
 #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)
+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;
 
-	error = security_syslog(type);
+	error = security_syslog(type, from_file);
 	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;
@@ -318,10 +305,12 @@ int do_syslog(int type, char __user *buf, int len)
 		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;
@@ -374,21 +363,25 @@ int do_syslog(int type, char __user *buf, int len)
 			}
 		}
 		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;
@@ -399,10 +392,12 @@ int do_syslog(int type, char __user *buf, int len)
 		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:
@@ -415,7 +410,7 @@ out:
 
 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);
 }
 
 /*
@@ -1376,11 +1371,11 @@ late_initcall(disable_boot_consoles);
  */
 DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
 
-int printk_ratelimit(void)
+int __printk_ratelimit(const char *func)
 {
-	return __ratelimit(&printk_ratelimit_state);
+	return ___ratelimit(&printk_ratelimit_state, func);
 }
-EXPORT_SYMBOL(printk_ratelimit);
+EXPORT_SYMBOL(__printk_ratelimit);
 
 /**
  * printk_timed_ratelimit - caller-controlled printk ratelimiting
@@ -1404,4 +1399,123 @@ bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 	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(&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(&dumper->list);
+		err = 0;
+	}
+	spin_unlock_irqrestore(&dump_list_lock, flags);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
+
+static const char const *kmsg_reasons[] = {
+	[KMSG_DUMP_OOPS]	= "oops",
+	[KMSG_DUMP_PANIC]	= "panic",
+	[KMSG_DUMP_KEXEC]	= "kexec",
+};
+
+static const char *kmsg_to_str(enum kmsg_dump_reason reason)
+{
+	if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0)
+		return "unknown";
+
+	return kmsg_reasons[reason];
+}
+
+/**
+ * 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 (logged_chars > end) {
+		s1 = log_buf + log_buf_len - logged_chars + end;
+		l1 = logged_chars - end;
+
+		s2 = log_buf;
+		l2 = end;
+	} else {
+		s1 = "";
+		l1 = 0;
+
+		s2 = log_buf + end - logged_chars;
+		l2 = logged_chars;
+	}
+
+	if (!spin_trylock_irqsave(&dump_list_lock, flags)) {
+		printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n",
+				kmsg_to_str(reason));
+		return;
+	}
+	list_for_each_entry(dumper, &dump_list, list)
+		dumper->dump(dumper, reason, s1, l1, s2, l2);
+	spin_unlock_irqrestore(&dump_list_lock, flags);
+}
 #endif