pstore: Add persistent function tracing

With this support kernel can save function call chain log into a
persistent ram buffer that can be decoded and dumped after reboot
through pstore filesystem. It can be used to determine what function
was last called before a reset or panic.

We store the log in a binary format and then decode it at read time.

p.s.
Mostly the code comes from trace_persistent.c driver found in the
Android git tree, written by Colin Cross <ccross@android.com>
(according to sign-off history). I reworked the driver a little bit,
and ported it to pstore.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index b107484192f..120443b0fda 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -30,6 +30,7 @@ enum pstore_type_id {
         PSTORE_TYPE_DMESG       = 0,
         PSTORE_TYPE_MCE         = 1,
         PSTORE_TYPE_CONSOLE     = 2,
+        PSTORE_TYPE_FTRACE      = 3,
         PSTORE_TYPE_UNKNOWN     = 255
 };
 
@@ -57,6 +58,14 @@ struct pstore_info {
         void            *data;
 };
 
+
+#ifdef CONFIG_PSTORE_FTRACE
+extern void pstore_ftrace_call(unsigned long ip, unsigned long parent_ip);
+#else
+static inline void pstore_ftrace_call(unsigned long ip, unsigned long parent_ip)
+{ }
+#endif
+
 #ifdef CONFIG_PSTORE
 extern int pstore_register(struct pstore_info *);
 #else