1 files changed, 148 insertions, 34 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 6712a252b306..ee54355cfdf1 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;
-
 /*
  * divert printk() messages when there is a LITMUS^RT debug listener
  */
@@ -150,6 +151,7 @@ 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
 /*
@@ -263,38 +265,23 @@ 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;
@@ -325,10 +312,12 @@ 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;
@@ -381,21 +370,25 @@ 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;
@@ -406,10 +399,12 @@ 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:
@@ -422,7 +417,7 @@ 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);
 }
 
 /*
@@ -1386,11 +1381,11 @@ 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
@@ -1414,4 +1409,123 @@ 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