pstore: Add console log messages support

Pstore doesn't support logging kernel messages in run-time, it only
dumps dmesg when kernel oopses/panics. This makes pstore useless for
debugging hangs caused by HW issues or improper use of HW (e.g.
weird device inserted -> driver tried to write a reserved bits ->
SoC hanged. In that case we don't get any messages in the pstore.

Therefore, let's add a runtime logging support: PSTORE_TYPE_CONSOLE.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Colin Cross <ccross@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 47 insertions, 0 deletions

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 23ade2680a4a..d044de6ee308 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -12,6 +12,13 @@ config PSTORE
            If you don't have a platform persistent store driver,
            say N.
 
+config PSTORE_CONSOLE
+        bool "Log kernel console messages"
+        depends on PSTORE
+        help
+          When the option is enabled, pstore will log all kernel
+          messages, even if no oops or panic happened.
+
 config PSTORE_RAM
         tristate "Log panic/oops to a RAM buffer"
         depends on PSTORE
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 11a2aa2a56c4..45bff5441b04 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -212,6 +212,9 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
         case PSTORE_TYPE_DMESG:
                 sprintf(name, "dmesg-%s-%lld", psname, id);
                 break;
+        case PSTORE_TYPE_CONSOLE:
+                sprintf(name, "console-%s", psname);
+                break;
         case PSTORE_TYPE_MCE:
                 sprintf(name, "mce-%s-%lld", psname, id);
                 break;
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 82c585f715e3..61461ed9b6c8 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -1,6 +1,7 @@
 /*
  * Persistent Storage - platform driver interface parts.
  *
+ * Copyright (C) 2007-2008 Google, Inc.
  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
  *
  *  This program is free software; you can redistribute it and/or modify
@@ -22,6 +23,7 @@
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kmsg_dump.h>
+#include <linux/console.h>
 #include <linux/module.h>
 #include <linux/pstore.h>
 #include <linux/string.h>
@@ -156,6 +158,40 @@ static struct kmsg_dumper pstore_dumper = {
         .dump = pstore_dump,
 };
 
+#ifdef CONFIG_PSTORE_CONSOLE
+static void pstore_console_write(struct console *con, const char *s, unsigned c)
+{
+        const char *e = s + c;
+
+        while (s < e) {
+                unsigned long flags;
+
+                if (c > psinfo->bufsize)
+                        c = psinfo->bufsize;
+                spin_lock_irqsave(&psinfo->buf_lock, flags);
+                memcpy(psinfo->buf, s, c);
+                psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
+                spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+                s += c;
+                c = e - s;
+        }
+}
+
+static struct console pstore_console = {
+        .name   = "pstore",
+        .write  = pstore_console_write,
+        .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
+        .index  = -1,
+};
+
+static void pstore_register_console(void)
+{
+        register_console(&pstore_console);
+}
+#else
+static void pstore_register_console(void) {}
+#endif
+
 /*
  * platform specific persistent storage driver registers with
  * us here. If pstore is already mounted, call the platform
@@ -193,6 +229,7 @@ int pstore_register(struct pstore_info *psi)
                 pstore_get_records(0);
 
         kmsg_dump_register(&pstore_dumper);
+        pstore_register_console();
 
         pstore_timer.expires = jiffies + PSTORE_INTERVAL;
         add_timer(&pstore_timer);