[V6,16/16] rv/reactor: Add the panic reactor

Commit Message

Daniel Bristot de Oliveira July 19, 2022, 5:27 p.m. UTC

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: Wim Van Sebroeck <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Marco Elver <[e-mail]>
Cc: Dmitry Vyukov <[e-mail]>
Cc: "Paul E. McKenney" <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: Gabriele Paoloni <[e-mail]>
Cc: Juri Lelli <[e-mail]>
Cc: Clark Williams <[e-mail]>
Cc: Tao Zhou <[e-mail]>
Cc: Randy Dunlap <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Daniel Bristot de Oliveira <[e-mail]>
---
 kernel/trace/rv/Kconfig         |  8 ++++++
 kernel/trace/rv/Makefile        |  1 +
 kernel/trace/rv/reactor_panic.c | 43 +++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 kernel/trace/rv/reactor_panic.c

Comments

Steven Rostedt July 21, 2022, 3:31 p.m. UTC | #1

On Tue, 19 Jul 2022 19:27:21 +0200
Daniel Bristot de Oliveira <[e-mail]> wrote:

> 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.

BTW, do you plan on adding models to model the reactors?

;-)

-- Steve

Daniel Bristot de Oliveira July 21, 2022, 4:43 p.m. UTC | #2

On 7/21/22 17:31, Steven Rostedt wrote:
> On Tue, 19 Jul 2022 19:27:21 +0200
> Daniel Bristot de Oliveira <[e-mail]> wrote:
> 
>> 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.
> 
> BTW, do you plan on adding models to model the reactors?

I was about to say that at the panic level, it would not be needed, as code inspection
is reasonable (people in Elisa did IIRC). But then I recalled that we
have a printk reactor, and one might model it - at event level :-)

But then can disable the reactor :-).

-- Daniel

> ;-)
> 
> -- Steve

Patch

diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index f1d92d431130..ce2a90a89f55 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -71,3 +71,11 @@  config RV_REACT_PRINTK
 	help
 	  Enables the printk reactor. The printk reactor emits a printk()
 	  message if an exception is found.
+
+config RV_REACT_PANIC
+	bool "Panic reactor"
+	depends on RV_REACTORS
+	default y
+	help
+	  Enables the panic reactor. The panic reactor emits a printk()
+	  message if an exception is found and panic()s the system.
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index a13c750a35c1..963d14875b45 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -5,3 +5,4 @@  obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o
 obj-$(CONFIG_RV_MON_WWNR) += monitors/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..e9757db801f3
--- /dev/null
+++ b/kernel/trace/rv/reactor_panic.c
@@ -0,0 +1,43 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira <[e-mail]>
+ *
+ * Panic RV reactor:
+ *   Prints the exception msg to the kernel message log and panic().
+ */
+
+#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);
+}
+
+static struct rv_reactor rv_panic = {
+	.name = "panic",
+	.description = "panic the system if an exception is found.",
+	.react = rv_panic_reaction
+};
+
+static int register_react_panic(void)
+{
+	rv_register_reactor(&rv_panic);
+	return 0;
+}
+
+static 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");