ANDROID: ftrace: vendor hook for ftrace dump on oops

Add following vendor hooks in ftrace oops path to allow
vendor modules to get ftrace buffer data.

1) android_vh_ftrace_format_check

Bug: 177387994
Change-Id: I898026bfc3e5c5c5ab1eaa0e86a019a6a720408e
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
(cherry picked from commit fbbc48ef18)

drivers/android/vendor_hooks.c

@@ -36,6 +36,7 @@
 #include <trace/hooks/timer.h>
 #include <trace/hooks/fpsimd.h>
 #include <trace/hooks/dtask.h>
+#include <trace/hooks/ftrace_dump.h>
 
 /*
  * Export tracepoints that act as a bare tracehook (ie: have no trace event
@@ -97,3 +98,4 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_rproc_recovery_set);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_timer_calc_index);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_is_fpsimd_save);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_sched_show_task);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ftrace_format_check);

include/trace/hooks/ftrace_dump.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM ftrace_dump
+
+#define TRACE_INCLUDE_PATH trace/hooks
+
+#if !defined(_TRACE_HOOK_FTRACE_DUMP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_HOOK_FTRACE_DUMP_H
+
+#include <trace/hooks/vendor_hooks.h>
+
+DECLARE_HOOK(android_vh_ftrace_format_check,
+	TP_PROTO(bool *ftrace_check),
+	TP_ARGS(ftrace_check));
+
+#endif /* _TRACE_HOOK_FTRACE_DUMP_H */
+/* This part must be outside protection */
+#include <trace/define_trace.h>

kernel/trace/trace.c

@@ -48,6 +48,7 @@
 #include <linux/fsnotify.h>
 #include <linux/irq_work.h>
 #include <linux/workqueue.h>
+#include <trace/hooks/ftrace_dump.h>
 
 #include <asm/setup.h> /* COMMAND_LINE_SIZE */
 
@@ -10246,6 +10247,7 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m
 	unsigned int old_userobj;
 	unsigned long flags;
 	int cnt = 0, cpu;
+	bool ftrace_check = true;
 
 	/*
 	 * Always turn off tracing when we dump.
@@ -10287,6 +10289,14 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m
 		printk("#          MAY BE MISSING FUNCTION EVENTS\n");
 	}
 
+	/*
+	 * Ftrace timestmap support two types:
+	 * - ftrace_check = 1, latency format, start with 0 from a specific time.
+	 * - ftrace_check = 0, absolute time format, consistent with kernel time.
+	 * With this vendor hook, we can choose the format from different requirement.
+	 */
+	trace_android_vh_ftrace_format_check(&ftrace_check);
+
 	/*
 	 * We need to stop all tracing on all CPUS to read
 	 * the next buffer. This is a bit expensive, but is
@@ -10295,14 +10305,14 @@ static void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_m
 	 */
 
 	while (!trace_empty(&iter)) {
-
 		if (!cnt)
 			printk(KERN_TRACE "---------------------------------\n");
 
 		cnt++;
 
 		trace_iterator_reset(&iter);
-		iter.iter_flags |= TRACE_FILE_LAT_FMT;
+		if (ftrace_check)
+			iter.iter_flags |= TRACE_FILE_LAT_FMT;
 
 		if (trace_find_next_entry_inc(&iter) != NULL) {
 			int ret;