Quelle  synth_event_gen_test.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * Test module for in-kernel synthetic event creation and generation.
 *
 * Copyright (C) 2019 Tom Zanussi <zanussi@kernel.org>
 */

#include <linux/module.h>
#include <linux/trace_events.h>

/*
 * This module is a simple test of basic functionality for in-kernel
 * synthetic event creation and generation, the first and second tests
 * using synth_event_gen_cmd_start() and synth_event_add_field(), the
 * third uses synth_event_create() to do it all at once with a static
 * field array.
 *
 * Following that are a few examples using the created events to test
 * various ways of tracing a synthetic event.
 *
 * To test, select CONFIG_SYNTH_EVENT_GEN_TEST and build the module.
 * Then:
 *
 * # insmod kernel/trace/synth_event_gen_test.ko
 * # cat /sys/kernel/tracing/trace
 *
 * You should see several events in the trace buffer -
 * "create_synth_test", "empty_synth_test", and several instances of
 * "gen_synth_test".
 *
 * To remove the events, remove the module:
 *
 * # rmmod synth_event_gen_test
 *
 */

static struct trace_event_file *create_synth_test;
static struct trace_event_file *empty_synth_test;
static struct trace_event_file *gen_synth_test;

/*
 * Test to make sure we can create a synthetic event, then add more
 * fields.
 */
static int __init test_gen_synth_cmd(void)
{
 struct dynevent_cmd cmd;
 u64 vals[7];
 char *buf;
 int ret;

 /* Create a buffer to hold the generated command */
 buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
 if (!buf)
  return -ENOMEM;

 /* Before generating the command, initialize the cmd object */
 synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);

 /*
 * Create the empty gen_synth_test synthetic event with the
 * first 4 fields.
 */
 ret = synth_event_gen_cmd_start(&cmd, "gen_synth_test", THIS_MODULE,
     "pid_t", "next_pid_field",
     "char[16]", "next_comm_field",
     "u64", "ts_ns",
     "u64", "ts_ms");
 if (ret)
  goto free;

 /* Use synth_event_add_field to add the rest of the fields */

 ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "int", "my_int_field");
 if (ret)
  goto free;

 ret = synth_event_gen_cmd_end(&cmd);
 if (ret)
  goto free;

 /*
 * Now get the gen_synth_test event file.  We need to prevent
 * the instance and event from disappearing from underneath
 * us, which trace_get_event_file() does (though in this case
 * we're using the top-level instance which never goes away).
 */
 gen_synth_test = trace_get_event_file(NULL, "synthetic",
           "gen_synth_test");
 if (IS_ERR(gen_synth_test)) {
  ret = PTR_ERR(gen_synth_test);
  goto delete;
 }

 /* Enable the event or you won't see anything */
 ret = trace_array_set_clr_event(gen_synth_test->tr,
     "synthetic", "gen_synth_test", true);
 if (ret) {
  trace_put_event_file(gen_synth_test);
  goto delete;
 }

 /* Create some bogus values just for testing */

 vals[0] = 777;   /* next_pid_field */
 vals[1] = (u64)(long)"hula hoops"; /* next_comm_field */
 vals[2] = 1000000;  /* ts_ns */
 vals[3] = 1000;   /* ts_ms */
 vals[4] = raw_smp_processor_id(); /* cpu */
 vals[5] = (u64)(long)"thneed"; /* my_string_field */
 vals[6] = 598;   /* my_int_field */

 /* Now generate a gen_synth_test event */
 ret = synth_event_trace_array(gen_synth_test, vals, ARRAY_SIZE(vals));
 free:
 kfree(buf);
 return ret;
 delete:
 /* We got an error after creating the event, delete it */
 synth_event_delete("gen_synth_test");
 goto free;
}

/*
 * Test to make sure we can create an initially empty synthetic event,
 * then add all the fields.
 */
static int __init test_empty_synth_event(void)
{
 struct dynevent_cmd cmd;
 u64 vals[7];
 char *buf;
 int ret;

 /* Create a buffer to hold the generated command */
 buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
 if (!buf)
  return -ENOMEM;

 /* Before generating the command, initialize the cmd object */
 synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);

 /*
 * Create the empty_synth_test synthetic event with no fields.
 */
 ret = synth_event_gen_cmd_start(&cmd, "empty_synth_test", THIS_MODULE);
 if (ret)
  goto free;

 /* Use synth_event_add_field to add all of the fields */

 ret = synth_event_add_field(&cmd, "pid_t", "next_pid_field");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "char[16]", "next_comm_field");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "u64", "ts_ns");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "u64", "ts_ms");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
 if (ret)
  goto free;

 ret = synth_event_add_field(&cmd, "int", "my_int_field");
 if (ret)
  goto free;

 /* All fields have been added, close and register the synth event */

 ret = synth_event_gen_cmd_end(&cmd);
 if (ret)
  goto free;

 /*
 * Now get the empty_synth_test event file.  We need to
 * prevent the instance and event from disappearing from
 * underneath us, which trace_get_event_file() does (though in
 * this case we're using the top-level instance which never
 * goes away).
 */
 empty_synth_test = trace_get_event_file(NULL, "synthetic",
      "empty_synth_test");
 if (IS_ERR(empty_synth_test)) {
  ret = PTR_ERR(empty_synth_test);
  goto delete;
 }

 /* Enable the event or you won't see anything */
 ret = trace_array_set_clr_event(empty_synth_test->tr,
     "synthetic", "empty_synth_test", true);
 if (ret) {
  trace_put_event_file(empty_synth_test);
  goto delete;
 }

 /* Create some bogus values just for testing */

 vals[0] = 777;   /* next_pid_field */
 vals[1] = (u64)(long)"tiddlywinks"; /* next_comm_field */
 vals[2] = 1000000;  /* ts_ns */
 vals[3] = 1000;   /* ts_ms */
 vals[4] = raw_smp_processor_id(); /* cpu */
 vals[5] = (u64)(long)"thneed_2.0"; /* my_string_field */
 vals[6] = 399;   /* my_int_field */

 /* Now trace an empty_synth_test event */
 ret = synth_event_trace_array(empty_synth_test, vals, ARRAY_SIZE(vals));
 free:
 kfree(buf);
 return ret;
 delete:
 /* We got an error after creating the event, delete it */
 synth_event_delete("empty_synth_test");
 goto free;
}

static struct synth_field_desc create_synth_test_fields[] = {
 { .type = "pid_t",  .name = "next_pid_field" },
 { .type = "char[16]",  .name = "next_comm_field" },
 { .type = "u64",  .name = "ts_ns" },
 { .type = "char[]",  .name = "dynstring_field_1" },
 { .type = "u64",  .name = "ts_ms" },
 { .type = "unsigned int", .name = "cpu" },
 { .type = "char[64]",  .name = "my_string_field" },
 { .type = "char[]",  .name = "dynstring_field_2" },
 { .type = "int",  .name = "my_int_field" },
};

/*
 * Test synthetic event creation all at once from array of field
 * descriptors.
 */
static int __init test_create_synth_event(void)
{
 u64 vals[9];
 int ret;

 /* Create the create_synth_test event with the fields above */
 ret = synth_event_create("create_synth_test",
     create_synth_test_fields,
     ARRAY_SIZE(create_synth_test_fields),
     THIS_MODULE);
 if (ret)
  goto out;

 /*
 * Now get the create_synth_test event file.  We need to
 * prevent the instance and event from disappearing from
 * underneath us, which trace_get_event_file() does (though in
 * this case we're using the top-level instance which never
 * goes away).
 */
 create_synth_test = trace_get_event_file(NULL, "synthetic",
       "create_synth_test");
 if (IS_ERR(create_synth_test)) {
  ret = PTR_ERR(create_synth_test);
  goto delete;
 }

 /* Enable the event or you won't see anything */
 ret = trace_array_set_clr_event(create_synth_test->tr,
     "synthetic", "create_synth_test", true);
 if (ret) {
  trace_put_event_file(create_synth_test);
  goto delete;
 }

 /* Create some bogus values just for testing */

 vals[0] = 777;   /* next_pid_field */
 vals[1] = (u64)(long)"tiddlywinks"; /* next_comm_field */
 vals[2] = 1000000;  /* ts_ns */
 vals[3] = (u64)(long)"xrayspecs"; /* dynstring_field_1 */
 vals[4] = 1000;   /* ts_ms */
 vals[5] = raw_smp_processor_id(); /* cpu */
 vals[6] = (u64)(long)"thneed"; /* my_string_field */
 vals[7] = (u64)(long)"kerplunk"; /* dynstring_field_2 */
 vals[8] = 398;   /* my_int_field */

 /* Now generate a create_synth_test event */
 ret = synth_event_trace_array(create_synth_test, vals, ARRAY_SIZE(vals));
 out:
 return ret;
 delete:
 /* We got an error after creating the event, delete it */
 synth_event_delete("create_synth_test");

 goto out;
}

/*
 * Test tracing a synthetic event by reserving trace buffer space,
 * then filling in fields one after another.
 */
static int __init test_add_next_synth_val(void)
{
 struct synth_event_trace_state trace_state;
 int ret;

 /* Start by reserving space in the trace buffer */
 ret = synth_event_trace_start(gen_synth_test, &trace_state);
 if (ret)
  return ret;

 /* Write some bogus values into the trace buffer, one after another */

 /* next_pid_field */
 ret = synth_event_add_next_val(777, &trace_state);
 if (ret)
  goto out;

 /* next_comm_field */
 ret = synth_event_add_next_val((u64)(long)"slinky", &trace_state);
 if (ret)
  goto out;

 /* ts_ns */
 ret = synth_event_add_next_val(1000000, &trace_state);
 if (ret)
  goto out;

 /* ts_ms */
 ret = synth_event_add_next_val(1000, &trace_state);
 if (ret)
  goto out;

 /* cpu */
 ret = synth_event_add_next_val(raw_smp_processor_id(), &trace_state);
 if (ret)
  goto out;

 /* my_string_field */
 ret = synth_event_add_next_val((u64)(long)"thneed_2.01", &trace_state);
 if (ret)
  goto out;

 /* my_int_field */
 ret = synth_event_add_next_val(395, &trace_state);
 out:
 /* Finally, commit the event */
 ret = synth_event_trace_end(&trace_state);

 return ret;
}

/*
 * Test tracing a synthetic event by reserving trace buffer space,
 * then filling in fields using field names, which can be done in any
 * order.
 */
static int __init test_add_synth_val(void)
{
 struct synth_event_trace_state trace_state;
 int ret;

 /* Start by reserving space in the trace buffer */
 ret = synth_event_trace_start(gen_synth_test, &trace_state);
 if (ret)
  return ret;

 /* Write some bogus values into the trace buffer, using field names */

 ret = synth_event_add_val("ts_ns", 1000000, &trace_state);
 if (ret)
  goto out;

 ret = synth_event_add_val("ts_ms", 1000, &trace_state);
 if (ret)
  goto out;

 ret = synth_event_add_val("cpu", raw_smp_processor_id(), &trace_state);
 if (ret)
  goto out;

 ret = synth_event_add_val("next_pid_field", 777, &trace_state);
 if (ret)
  goto out;

 ret = synth_event_add_val("next_comm_field", (u64)(long)"silly putty",
      &trace_state);
 if (ret)
  goto out;

 ret = synth_event_add_val("my_string_field", (u64)(long)"thneed_9",
      &trace_state);
 if (ret)
  goto out;

 ret = synth_event_add_val("my_int_field", 3999, &trace_state);
 out:
 /* Finally, commit the event */
 ret = synth_event_trace_end(&trace_state);

 return ret;
}

/*
 * Test tracing a synthetic event all at once from array of values.
 */
static int __init test_trace_synth_event(void)
{
 int ret;

 /* Trace some bogus values just for testing */
 ret = synth_event_trace(create_synth_test, 9, /* number of values */
    (u64)444,  /* next_pid_field */
    (u64)(long)"clackers", /* next_comm_field */
    (u64)1000000,  /* ts_ns */
    (u64)(long)"viewmaster",/* dynstring_field_1 */
    (u64)1000,  /* ts_ms */
    (u64)raw_smp_processor_id(), /* cpu */
    (u64)(long)"Thneed", /* my_string_field */
    (u64)(long)"yoyos", /* dynstring_field_2 */
    (u64)999);  /* my_int_field */
 return ret;
}

static int __init synth_event_gen_test_init(void)
{
 int ret;

 ret = test_gen_synth_cmd();
 if (ret)
  return ret;

 ret = test_empty_synth_event();
 if (ret) {
  WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
        "synthetic",
        "gen_synth_test", false));
  trace_put_event_file(gen_synth_test);
  WARN_ON(synth_event_delete("gen_synth_test"));
  goto out;
 }

 ret = test_create_synth_event();
 if (ret) {
  WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
        "synthetic",
        "gen_synth_test", false));
  trace_put_event_file(gen_synth_test);
  WARN_ON(synth_event_delete("gen_synth_test"));

  WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
        "synthetic",
        "empty_synth_test", false));
  trace_put_event_file(empty_synth_test);
  WARN_ON(synth_event_delete("empty_synth_test"));
  goto out;
 }

 ret = test_add_next_synth_val();
 WARN_ON(ret);

 ret = test_add_synth_val();
 WARN_ON(ret);

 ret = test_trace_synth_event();
 WARN_ON(ret);

 /* Disable when done */
 trace_array_set_clr_event(gen_synth_test->tr,
      "synthetic",
      "gen_synth_test", false);
 trace_array_set_clr_event(empty_synth_test->tr,
      "synthetic",
      "empty_synth_test", false);
 trace_array_set_clr_event(create_synth_test->tr,
      "synthetic",
      "create_synth_test", false);
 out:
 return ret;
}

static void __exit synth_event_gen_test_exit(void)
{
 /* Disable the event or you can't remove it */
 WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
       "synthetic",
       "gen_synth_test", false));

 /* Now give the file and instance back */
 trace_put_event_file(gen_synth_test);

 /* Now unregister and free the synthetic event */
 WARN_ON(synth_event_delete("gen_synth_test"));

 /* Disable the event or you can't remove it */
 WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
       "synthetic",
       "empty_synth_test", false));

 /* Now give the file and instance back */
 trace_put_event_file(empty_synth_test);

 /* Now unregister and free the synthetic event */
 WARN_ON(synth_event_delete("empty_synth_test"));

 /* Disable the event or you can't remove it */
 WARN_ON(trace_array_set_clr_event(create_synth_test->tr,
       "synthetic",
       "create_synth_test", false));

 /* Now give the file and instance back */
 trace_put_event_file(create_synth_test);

 /* Now unregister and free the synthetic event */
 WARN_ON(synth_event_delete("create_synth_test"));
}

module_init(synth_event_gen_test_init)
module_exit(synth_event_gen_test_exit)

MODULE_AUTHOR("Tom Zanussi");
MODULE_DESCRIPTION("synthetic event generation test");
MODULE_LICENSE("GPL v2");