linux/kernel/trace/synth_event_gen_test.c
Steven Rostedt (Google) 88b30c7f5d tracing / synthetic: Disable events after testing in synth_event_gen_test_init()
The synth_event_gen_test module can be built in, if someone wants to run
the tests at boot up and not have to load them.

The synth_event_gen_test_init() function creates and enables the synthetic
events and runs its tests.

The synth_event_gen_test_exit() disables the events it created and
destroys the events.

If the module is builtin, the events are never disabled. The issue is, the
events should be disable after the tests are run. This could be an issue
if the rest of the boot up tests are enabled, as they expect the events to
be in a known state before testing. That known state happens to be
disabled.

When CONFIG_SYNTH_EVENT_GEN_TEST=y and CONFIG_EVENT_TRACE_STARTUP_TEST=y
a warning will trigger:

 Running tests on trace events:
 Testing event create_synth_test:
 Enabled event during self test!
 ------------[ cut here ]------------
 WARNING: CPU: 2 PID: 1 at kernel/trace/trace_events.c:4150 event_trace_self_tests+0x1c2/0x480
 Modules linked in:
 CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc2-test-00031-gb803d7c664d5-dirty #276
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
 RIP: 0010:event_trace_self_tests+0x1c2/0x480
 Code: bb e8 a2 ab 5d fc 48 8d 7b 48 e8 f9 3d 99 fc 48 8b 73 48 40 f6 c6 01 0f 84 d6 fe ff ff 48 c7 c7 20 b6 ad bb e8 7f ab 5d fc 90 <0f> 0b 90 48 89 df e8 d3 3d 99 fc 48 8b 1b 4c 39 f3 0f 85 2c ff ff
 RSP: 0000:ffffc9000001fdc0 EFLAGS: 00010246
 RAX: 0000000000000029 RBX: ffff88810399ca80 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: ffffffffb9f19478 RDI: ffff88823c734e64
 RBP: ffff88810399f300 R08: 0000000000000000 R09: fffffbfff79eb32a
 R10: ffffffffbcf59957 R11: 0000000000000001 R12: ffff888104068090
 R13: ffffffffbc89f0a0 R14: ffffffffbc8a0f08 R15: 0000000000000078
 FS:  0000000000000000(0000) GS:ffff88823c700000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 00000001f6282001 CR4: 0000000000170ef0
 Call Trace:
  <TASK>
  ? __warn+0xa5/0x200
  ? event_trace_self_tests+0x1c2/0x480
  ? report_bug+0x1f6/0x220
  ? handle_bug+0x6f/0x90
  ? exc_invalid_op+0x17/0x50
  ? asm_exc_invalid_op+0x1a/0x20
  ? tracer_preempt_on+0x78/0x1c0
  ? event_trace_self_tests+0x1c2/0x480
  ? __pfx_event_trace_self_tests_init+0x10/0x10
  event_trace_self_tests_init+0x27/0xe0
  do_one_initcall+0xd6/0x3c0
  ? __pfx_do_one_initcall+0x10/0x10
  ? kasan_set_track+0x25/0x30
  ? rcu_is_watching+0x38/0x60
  kernel_init_freeable+0x324/0x450
  ? __pfx_kernel_init+0x10/0x10
  kernel_init+0x1f/0x1e0
  ? _raw_spin_unlock_irq+0x33/0x50
  ret_from_fork+0x34/0x60
  ? __pfx_kernel_init+0x10/0x10
  ret_from_fork_asm+0x1b/0x30
  </TASK>

This is because the synth_event_gen_test_init() left the synthetic events
that it created enabled. By having it disable them after testing, the
other selftests will run fine.

Link: https://lore.kernel.org/linux-trace-kernel/20231220111525.2f0f49b0@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 9fe41efaca ("tracing: Add synth event generation test module")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Alexander Graf <graf@amazon.com>
Tested-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-12-21 10:04:45 -05:00

537 lines
14 KiB
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");