@@ -1933,6 +1933,14 @@ config TEST_KMOD
If unsure, say N.
+config TEST_ATOMIC_SECTIONS
+ tristate "Simulate atomic sections for tracers to detect"
+ depends on m
+ help
+ Select this option to build a test module that can help test atomic
+ sections by simulating them with a duration supplied as a module
+ parameter. Preempt disable and irq disable modes can be requested.
+
config TEST_DEBUG_VIRTUAL
tristate "Test CONFIG_DEBUG_VIRTUAL feature"
depends on DEBUG_VIRTUAL
@@ -46,6 +46,7 @@ obj-y += string_helpers.o
obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
obj-y += hexdump.o
obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o
+obj-$(CONFIG_TEST_ATOMIC_SECTIONS) += test_atomic_sections.o
obj-y += kstrtox.o
obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o
obj-$(CONFIG_TEST_BPF) += test_bpf.o
new file mode 100644
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Atomic section emulation test module
+ *
+ * Emulates atomic sections by disabling IRQs or preemption
+ * and doing a busy wait for a specified amount of time.
+ * This can be used for testing of different atomic section
+ * tracers such as irqsoff tracers.
+ *
+ * (c) 2018. Google LLC
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/string.h>
+
+static ulong atomic_time = 100;
+static char atomic_mode[10] = "irq";
+
+module_param_named(atomic_time, atomic_time, ulong, S_IRUGO);
+module_param_string(atomic_mode, atomic_mode, 10, S_IRUGO);
+MODULE_PARM_DESC(atomic_time, "Period in microseconds (100 uS default)");
+MODULE_PARM_DESC(atomic_mode, "Mode of the test such as preempt or irq (default irq)");
+
+static void busy_wait(ulong time)
+{
+ ktime_t start, end;
+ start = ktime_get();
+ do {
+ end = ktime_get();
+ if (kthread_should_stop())
+ break;
+ } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000));
+}
+
+int atomic_sect_run(void *data)
+{
+ unsigned long flags;
+
+ if (!strcmp(atomic_mode, "irq")) {
+ local_irq_save(flags);
+ busy_wait(atomic_time);
+ local_irq_restore(flags);
+ } else if (!strcmp(atomic_mode, "preempt")) {
+ preempt_disable();
+ busy_wait(atomic_time);
+ preempt_enable();
+ }
+
+ return 0;
+}
+
+static int __init atomic_sect_init(void)
+{
+ char task_name[50];
+ struct task_struct *test_task;
+
+ snprintf(task_name, sizeof(task_name), "%s_test", atomic_mode);
+
+ test_task = kthread_run(atomic_sect_run, NULL, task_name);
+ return PTR_ERR_OR_ZERO(test_task);
+}
+
+static void __exit atomic_sect_exit(void)
+{
+ return;
+}
+
+module_init(atomic_sect_init)
+module_exit(atomic_sect_exit)
+MODULE_LICENSE("GPL v2");