ANDROID: vendor_hooks: Add vendor hooks for getting printk messages

When sudden reset by watchdog occurs, kernel log is very helpful.
But the log has saved structure type in log_buf.
So we want to collect the log on runtime to string format at other
reserved memory.

Bug: 167766040

Change-Id: Ic9686acc7c284e2ab81395fb9cc076fafe142bf9
Signed-off-by: Changki Kim <changki.kim@samsung.com>

drivers/android/vendor_hooks.c

@@ -55,3 +55,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alter_rwsem_list_add);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alter_futex_plist_add);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_is_fpsimd_save);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ipi_stop);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_printk_store);

include/trace/hooks/debug.h

@@ -15,8 +15,13 @@ struct pt_regs;
 DECLARE_HOOK(android_vh_ipi_stop,
 	TP_PROTO(struct pt_regs *regs),
 	TP_ARGS(regs))
+
+DECLARE_HOOK(android_vh_printk_store,
+	TP_PROTO(int facility, int level),
+	TP_ARGS(facility, level))
 #else
 #define trace_android_vh_ipi_stop(regs)
+#define trace_android_vh_printk_store(facility, level)
 #endif
 
 #endif /* _TRACE_HOOK_DEBUG_H */

kernel/printk/printk.c

@@ -55,6 +55,8 @@
 #include <trace/events/initcall.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/printk.h>
+#undef CREATE_TRACE_POINTS
+#include <trace/hooks/debug.h>
 
 #include "console_cmdline.h"
 #include "braille.h"
@@ -2007,6 +2009,7 @@ asmlinkage int vprintk_emit(int facility, int level,
 	pending_output = (curr_log_seq != log_next_seq);
 	logbuf_unlock_irqrestore(flags);
 
+	trace_android_vh_printk_store(facility, level);
 	/* If called from the scheduler, we can not call up(). */
 	if (!in_sched && pending_output) {
 		/*