[PATCH 2/2] kselftests: ftrace: Add tests for the preemptoff and irqsoff tracers

[Joel Fernandes <joelaf@google.com>]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

Here we add unit tests for the preemptoff and irqsoff tracer by using a
kernel module introduced previously to trigger atomic sections in the
kernel.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zilstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Glexiner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Todd Kjos <tkjos@google.com>
Cc: Erick Reyes <erickreyes@google.com>
Cc: Julia Cartwright <julia@ni.com>
Cc: kernel-team@android.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 tools/testing/selftests/ftrace/config         |  3 +
 .../test.d/preemptirq/irqsoff_tracer.tc       | 74 +++++++++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc

diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftests/ftrace/config
index b01924c71c09..29588b328345 100644
--- a/tools/testing/selftests/ftrace/config
+++ b/tools/testing/selftests/ftrace/config
@@ -4,3 +4,6 @@ CONFIG_FUNCTION_PROFILER=y
 CONFIG_TRACER_SNAPSHOT=y
 CONFIG_STACK_TRACER=y
 CONFIG_HIST_TRIGGERS=y
+CONFIG_PREEMPT_TRACER=y
+CONFIG_IRQSOFF_TRACER=y
+CONFIG_TEST_ATOMIC_SECTIONS=m
diff --git a/tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc b/tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc
new file mode 100644
index 000000000000..b76d781c5645
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc
@@ -0,0 +1,74 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: test for the preemptirqsoff tracer
+
+MOD=test_atomic_sections
+
+fail() {
+    reset_tracer
+    rmmod $MOD || true
+    exit_fail
+}
+
+unsup() { #msg
+    reset_tracer
+    rmmod $MOD || true
+    echo $1
+    exit_unsupported
+}
+
+modprobe $MOD || unsup "$MOD module not available"
+rmmod $MOD
+
+grep "preemptoff" available_tracers || unsup "preemptoff tracer not enabled"
+grep "irqsoff" available_tracers || unsup "irqsoff tracer not enabled"
+
+reset_tracer
+
+# Simulate preemptoff section for half a second couple of times
+echo preemptoff > current_tracer
+sleep 1
+modprobe test_atomic_sections atomic_mode=preempt atomic_time=500000 || fail
+rmmod test_atomic_sections || fail
+modprobe test_atomic_sections atomic_mode=preempt atomic_time=500000 || fail
+rmmod test_atomic_sections || fail
+modprobe test_atomic_sections atomic_mode=preempt atomic_time=500000 || fail
+rmmod test_atomic_sections || fail
+
+cat trace
+
+# Confirm which tracer
+grep "tracer: preemptoff" trace || fail
+
+# Check the end of the section
+egrep "5.....us : <stack trace>" trace || fail
+
+# Check for 500ms of latency
+egrep "latency: 5..... us" trace || fail
+
+reset_tracer
+
+# Simulate irqsoff section for half a second couple of times
+echo irqsoff > current_tracer
+sleep 1
+modprobe test_atomic_sections atomic_mode=irq atomic_time=500000 || fail
+rmmod test_atomic_sections || fail
+modprobe test_atomic_sections atomic_mode=irq atomic_time=500000 || fail
+rmmod test_atomic_sections || fail
+modprobe test_atomic_sections atomic_mode=irq atomic_time=500000 || fail
+rmmod test_atomic_sections || fail
+
+cat trace
+
+# Confirm which tracer
+grep "tracer: irqsoff" trace || fail
+
+# Check the end of the section
+egrep "5.....us : <stack trace>" trace || fail
+
+# Check for 500ms of latency
+egrep "latency: 5..... us" trace || fail
+
+reset_tracer
+exit 0
+
-- 
2.17.0.441.gb46fe60e1d-goog