coresight: add event to abort tracing on kernel panic

Add trace event to control aborting CoreSight trace
dynamically based on module parameter. This will help
user to enable/disable coresight_abort on kernel panic.
Also moved CREATE_TRACE_POINTS to panic.c from fault.c
since panic.c is common and shared between 32 and 64
bit platforms.

Change-Id: I51e4049b07adeca571b1a98cd90ff5f307d1d794
Signed-off-by: Sarang Joshi <spjoshi@codeaurora.org>

arch/arm/mm/fault.c

@@ -32,7 +32,6 @@
 
 #include "fault.h"
 
-#define CREATE_TRACE_POINTS
 #include <trace/events/exception.h>
 
 #ifdef CONFIG_MMU

drivers/coresight/Kconfig

@@ -21,6 +21,14 @@ menuconfig CORESIGHT
 
 if CORESIGHT
 
+config CORESIGHT_EVENT
+	tristate "CoreSight Event driver"
+	help
+	  This driver provides support for registering with various events
+	  and performing CoreSight actions like aborting trace on their
+	  occurrence. These events can be controlled by using module
+	  parameters.
+
 config HAVE_CORESIGHT_SINK
 	bool
 
@@ -178,11 +186,4 @@ config CORESIGHT_RPM_ETM
 
 endif
 
-config CORESIGHT_EVENT
-	tristate "CoreSight Event driver"
-	help
-	  This driver provides support for registering with various events
-	  and performing CoreSight actions like aborting trace on their
-	  occurrence.
-
 endif

drivers/coresight/Makefile

@@ -2,6 +2,7 @@
 # Makefile for CoreSight drivers.
 #
 obj-$(CONFIG_CORESIGHT) += coresight.o
+obj-$(CONFIG_CORESIGHT_EVENT) += coresight-event.o
 obj-$(CONFIG_CORESIGHT_FUSE) += coresight-fuse.o
 obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o
 obj-$(CONFIG_CORESIGHT_CSR) += coresight-csr.o
@@ -16,4 +17,3 @@ obj-$(CONFIG_CORESIGHT_AUDIO_ETM) += coresight-audio-etm.o
 obj-$(CONFIG_CORESIGHT_MODEM_ETM) += coresight-modem-etm.o
 obj-$(CONFIG_CORESIGHT_WCN_ETM) += coresight-wcn-etm.o
 obj-$(CONFIG_CORESIGHT_RPM_ETM) += coresight-rpm-etm.o
-obj-$(CONFIG_CORESIGHT_EVENT) += coresight-event.o

drivers/coresight/coresight-event.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2012-2014, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -25,6 +25,11 @@ static int event_abort_set(const char *val, struct kernel_param *kp);
 module_param_call(event_abort_enable, event_abort_set, param_get_int,
 		  &event_abort_enable, 0644);
 
+static int event_abort_on_panic = 1;
+static int event_abort_on_panic_set(const char *val, struct kernel_param *kp);
+module_param_call(event_abort_on_panic, event_abort_on_panic_set, param_get_int,
+		  &event_abort_on_panic, 0644);
+
 static void event_abort_user_fault(void *ignore,
 				   struct task_struct *task,
 				   unsigned long addr,
@@ -56,6 +61,11 @@ static void event_abort_unhandled_abort(void *ignore,
 	}
 }
 
+static void event_abort_kernel_panic(void *ignore, long state)
+{
+	coresight_abort();
+}
+
 static int event_abort_register(void)
 {
 	int ret;
@@ -105,14 +115,43 @@ static int event_abort_set(const char *val, struct kernel_param *kp)
 	return ret;
 }
 
+static int event_abort_on_panic_set(const char *val, struct kernel_param *kp)
+{
+	int ret;
+
+	ret = param_set_int(val, kp);
+	if (ret) {
+		pr_err("coresight_event: error setting val on panic %d\n", ret);
+		return ret;
+	}
+
+	if (event_abort_on_panic)
+		ret = register_trace_kernel_panic(event_abort_kernel_panic,
+						  NULL);
+	else
+		unregister_trace_kernel_panic(event_abort_kernel_panic, NULL);
+
+	return ret;
+}
+
 static int __init event_init(void)
 {
+	int ret;
+
+	ret = register_trace_kernel_panic(event_abort_kernel_panic, NULL);
+	if (ret) {
+		/* We do not want to fail module init. This module can still
+		 * be used to register other abort events.
+		 */
+		pr_err("coresight_event: error registering on panic %d\n", ret);
+	}
 	return 0;
 }
 module_init(event_init);
 
 static void __exit event_exit(void)
 {
+	unregister_trace_kernel_panic(event_abort_kernel_panic, NULL);
 }
 module_exit(event_exit);
 

include/trace/events/exception.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2012-2014, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -84,6 +84,23 @@ TRACE_EVENT(unhandled_abort,
 	TP_printk("addr:%lu, fsr:%u", __entry->addr, __entry->fsr)
 );
 
+TRACE_EVENT(kernel_panic,
+
+	TP_PROTO(long dummy),
+
+	TP_ARGS(dummy),
+
+	TP_STRUCT__entry(
+		__field(long, dummy)
+	),
+
+	TP_fast_assign(
+		__entry->dummy	= dummy;
+	),
+
+	TP_printk("dummy:%ld", __entry->dummy)
+);
+
 #endif
 
 #include <trace/define_trace.h>

kernel/panic.c

@@ -22,7 +22,9 @@
 #include <linux/sysrq.h>
 #include <linux/init.h>
 #include <linux/nmi.h>
-#include <linux/coresight.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/exception.h>
 
 #define PANIC_TIMER_STEP 100
 #define PANIC_BLINK_SPD 18
@@ -80,7 +82,7 @@ void panic(const char *fmt, ...)
 	long i, i_next = 0;
 	int state = 0;
 
-	coresight_abort();
+	trace_kernel_panic(0);
 	/*
 	 * Disable local interrupts. This will prevent panic_smp_self_stop
 	 * from deadlocking the first cpu that invokes the panic, since