[RFC V3 13/20] rv/reactor: Add the panic reactor

[Daniel Bristot de Oliveira <bristot@kernel.org>]

Sample reactor that panics the system when an exception is found. This
is useful both to capture a vmcore, or to fail-safe a critical system.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
---
 kernel/trace/rv/Kconfig         |  8 ++++++
 kernel/trace/rv/Makefile        |  1 +
 kernel/trace/rv/reactor_panic.c | 44 +++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+)
 create mode 100644 kernel/trace/rv/reactor_panic.c

diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index 8c54ae473846..a2999c37c037 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -45,4 +45,12 @@ config RV_REACT_PRINTK
 	  Enables the printk reactor. The printk reactor emmits a printk()
 	  message if an exception is found.
 
+config RV_REACT_PANIC
+	bool "Panic reactor"
+	depends on RV_REACTORS
+	default y if RV_REACTORS
+	help
+	  Enables the panic reactor. The panic reactor emmits a printk()
+	  message if an exception is found and panic()s the system.
+
 endif # RV
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index d86ceb103ef2..1f5747f065ce 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -5,3 +5,4 @@ obj-$(CONFIG_RV_MON_WIP) += monitor_wip/wip.o
 obj-$(CONFIG_RV_MON_WWNR) += monitor_wwnr/wwnr.o
 obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
 obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
+obj-$(CONFIG_RV_REACT_PANIC) += reactor_panic.o
diff --git a/kernel/trace/rv/reactor_panic.c b/kernel/trace/rv/reactor_panic.c
new file mode 100644
index 000000000000..9d8d78a337a3
--- /dev/null
+++ b/kernel/trace/rv/reactor_panic.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Panic RV reactor:
+ *   Prints the exception msg to the kernel message log and panic().
+ *
+ * Copyright (C) 2019-2022 Daniel Bristot de Oliveira <bristot@kernel.org>
+ *
+ */
+
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+
+static void rv_panic_reaction(char *msg)
+{
+	panic(msg);
+}
+
+struct rv_reactor rv_panic = {
+	.name = "panic",
+	.description = "panic the system if an exception is found.",
+	.react = rv_panic_reaction
+};
+
+int register_react_panic(void)
+{
+	rv_register_reactor(&rv_panic);
+	return 0;
+}
+
+void unregister_react_panic(void)
+{
+	rv_unregister_reactor(&rv_panic);
+}
+
+module_init(register_react_panic);
+module_exit(unregister_react_panic);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Daniel Bristot de Oliveira");
+MODULE_DESCRIPTION("panic rv reactor: panic if an exception is found");
-- 
2.35.1