| // 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/debug/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"); |