// SPDX-License-Identifier: GPL-2.0/* * Test module for in-kernel kprobe 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 * kprobe/kretprobe event creation.  The first test uses * kprobe_event_gen_cmd_start(), kprobe_event_add_fields() and * kprobe_event_gen_cmd_end() to create a kprobe event, which is then * enabled in order to generate trace output.  The second creates a * kretprobe event using kretprobe_event_gen_cmd_start() and * kretprobe_event_gen_cmd_end(), and is also then enabled. * * To test, select CONFIG_KPROBE_EVENT_GEN_TEST and build the module. * Then: * * # insmod kernel/trace/kprobe_event_gen_test.ko * # cat /sys/kernel/tracing/trace * * You should see many instances of the "gen_kprobe_test" and * "gen_kretprobe_test" events in the trace buffer. * * To remove the events, remove the module: * * # rmmod kprobe_event_gen_test * */ static struct trace_event_file *gen_kprobe_test;static struct trace_event_file *gen_kretprobe_test; #define KPROBE_GEN_TEST_FUNC	"do_sys_open" /* X86 */#if defined(CONFIG_X86_64) || defined(CONFIG_X86_32)#define KPROBE_GEN_TEST_ARG0	"dfd=%ax"#define KPROBE_GEN_TEST_ARG1	"filename=%dx"#define KPROBE_GEN_TEST_ARG2	"flags=%cx"#define KPROBE_GEN_TEST_ARG3	"mode=+4($stack)" /* ARM64 */#elif defined(CONFIG_ARM64)#define KPROBE_GEN_TEST_ARG0	"dfd=%x0"#define KPROBE_GEN_TEST_ARG1	"filename=%x1"#define KPROBE_GEN_TEST_ARG2	"flags=%x2"#define KPROBE_GEN_TEST_ARG3	"mode=%x3" /* ARM */#elif defined(CONFIG_ARM)#define KPROBE_GEN_TEST_ARG0	"dfd=%r0"#define KPROBE_GEN_TEST_ARG1	"filename=%r1"#define KPROBE_GEN_TEST_ARG2	"flags=%r2"#define KPROBE_GEN_TEST_ARG3	"mode=%r3" /* RISCV */#elif defined(CONFIG_RISCV)#define KPROBE_GEN_TEST_ARG0	"dfd=%a0"#define KPROBE_GEN_TEST_ARG1	"filename=%a1"#define KPROBE_GEN_TEST_ARG2	"flags=%a2"#define KPROBE_GEN_TEST_ARG3	"mode=%a3" /* others */#else#define KPROBE_GEN_TEST_ARG0	NULL#define KPROBE_GEN_TEST_ARG1	NULL#define KPROBE_GEN_TEST_ARG2	NULL#define KPROBE_GEN_TEST_ARG3	NULL#endif static bool trace_event_file_is_valid(struct trace_event_file *input){	return input && !IS_ERR(input);} /* * Test to make sure we can create a kprobe event, then add more * fields. */static int __init test_gen_kprobe_cmd(void){	struct dynevent_cmd cmd;	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 */	kprobe_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN); 	/*	 * Define the gen_kprobe_test event with the first 2 kprobe	 * fields.	 */	ret = kprobe_event_gen_cmd_start(&cmd, "gen_kprobe_test",					 KPROBE_GEN_TEST_FUNC,					 KPROBE_GEN_TEST_ARG0, KPROBE_GEN_TEST_ARG1);	if (ret)		goto out; 	/* Use kprobe_event_add_fields to add the rest of the fields */ 	ret = kprobe_event_add_fields(&cmd, KPROBE_GEN_TEST_ARG2, KPROBE_GEN_TEST_ARG3);	if (ret)		goto out; 	/*	 * This actually creates the event.	 */	ret = kprobe_event_gen_cmd_end(&cmd);	if (ret)		goto out; 	/*	 * Now get the gen_kprobe_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_kprobe_test = trace_get_event_file(NULL, "kprobes",					       "gen_kprobe_test");	if (IS_ERR(gen_kprobe_test)) {		ret = PTR_ERR(gen_kprobe_test);		goto delete;	} 	/* Enable the event or you won't see anything */	ret = trace_array_set_clr_event(gen_kprobe_test->tr,					"kprobes", "gen_kprobe_test", true);	if (ret) {		trace_put_event_file(gen_kprobe_test);		goto delete;	} out:	kfree(buf);	return ret; delete:	if (trace_event_file_is_valid(gen_kprobe_test))		gen_kprobe_test = NULL;	/* We got an error after creating the event, delete it */	kprobe_event_delete("gen_kprobe_test");	goto out;} /* * Test to make sure we can create a kretprobe event. */static int __init test_gen_kretprobe_cmd(void){	struct dynevent_cmd cmd;	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 */	kprobe_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN); 	/*	 * Define the kretprobe event.	 */	ret = kretprobe_event_gen_cmd_start(&cmd, "gen_kretprobe_test",					    KPROBE_GEN_TEST_FUNC,					    "$retval");	if (ret)		goto out; 	/*	 * This actually creates the event.	 */	ret = kretprobe_event_gen_cmd_end(&cmd);	if (ret)		goto out; 	/*	 * Now get the gen_kretprobe_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_kretprobe_test = trace_get_event_file(NULL, "kprobes",						  "gen_kretprobe_test");	if (IS_ERR(gen_kretprobe_test)) {		ret = PTR_ERR(gen_kretprobe_test);		goto delete;	} 	/* Enable the event or you won't see anything */	ret = trace_array_set_clr_event(gen_kretprobe_test->tr,					"kprobes", "gen_kretprobe_test", true);	if (ret) {		trace_put_event_file(gen_kretprobe_test);		goto delete;	} out:	kfree(buf);	return ret; delete:	if (trace_event_file_is_valid(gen_kretprobe_test))		gen_kretprobe_test = NULL;	/* We got an error after creating the event, delete it */	kprobe_event_delete("gen_kretprobe_test");	goto out;} static int __init kprobe_event_gen_test_init(void){	int ret; 	ret = test_gen_kprobe_cmd();	if (ret)		return ret; 	ret = test_gen_kretprobe_cmd();	if (ret) {		if (trace_event_file_is_valid(gen_kretprobe_test)) {			WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,							  "kprobes",							  "gen_kretprobe_test", false));			trace_put_event_file(gen_kretprobe_test);		}		WARN_ON(kprobe_event_delete("gen_kretprobe_test"));	} 	return ret;} static void __exit kprobe_event_gen_test_exit(void){	if (trace_event_file_is_valid(gen_kprobe_test)) {		/* Disable the event or you can't remove it */		WARN_ON(trace_array_set_clr_event(gen_kprobe_test->tr,						  "kprobes",						  "gen_kprobe_test", false)); 		/* Now give the file and instance back */		trace_put_event_file(gen_kprobe_test);	}  	/* Now unregister and free the event */	WARN_ON(kprobe_event_delete("gen_kprobe_test")); 	if (trace_event_file_is_valid(gen_kretprobe_test)) {		/* Disable the event or you can't remove it */		WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,						  "kprobes",						  "gen_kretprobe_test", false)); 		/* Now give the file and instance back */		trace_put_event_file(gen_kretprobe_test);	}  	/* Now unregister and free the event */	WARN_ON(kprobe_event_delete("gen_kretprobe_test"));} module_init(kprobe_event_gen_test_init)module_exit(kprobe_event_gen_test_exit) MODULE_AUTHOR("Tom Zanussi");MODULE_DESCRIPTION("kprobe event generation test");MODULE_LICENSE("GPL v2");