| 1 | /* |
| 2 | * (C) Copyright 2009-2011 - |
| 3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * |
| 5 | * LTTng function tracer integration module. |
| 6 | * |
| 7 | * Dual LGPL v2.1/GPL v2 license. |
| 8 | */ |
| 9 | |
| 10 | /* |
| 11 | * Ftrace function tracer does not seem to provide synchronization between probe |
| 12 | * teardown and callback execution. Therefore, we make this module permanently |
| 13 | * loaded (unloadable). |
| 14 | */ |
| 15 | |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/ftrace.h> |
| 18 | #include <linux/slab.h> |
| 19 | #include "../ltt-events.h" |
| 20 | #include "../wrapper/ringbuffer/frontend_types.h" |
| 21 | #include "../wrapper/ftrace.h" |
| 22 | #include "../ltt-tracer.h" |
| 23 | |
| 24 | static |
| 25 | void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data) |
| 26 | { |
| 27 | struct ltt_event *event = *data; |
| 28 | struct ltt_channel *chan = event->chan; |
| 29 | struct lib_ring_buffer_ctx ctx; |
| 30 | struct { |
| 31 | unsigned long ip; |
| 32 | unsigned long parent_ip; |
| 33 | } payload; |
| 34 | int ret; |
| 35 | |
| 36 | if (!ACCESS_ONCE(chan->session->active)) |
| 37 | return; |
| 38 | lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, |
| 39 | sizeof(payload), ltt_alignof(payload), -1); |
| 40 | ret = chan->ops->event_reserve(&ctx); |
| 41 | if (ret < 0) |
| 42 | return; |
| 43 | payload.ip = ip; |
| 44 | payload.parent_ip = parent_ip; |
| 45 | lib_ring_buffer_align_ctx(&ctx, ltt_alignof(payload)); |
| 46 | chan->ops->event_write(&ctx, &payload, sizeof(payload)); |
| 47 | chan->ops->event_commit(&ctx); |
| 48 | return; |
| 49 | } |
| 50 | |
| 51 | /* |
| 52 | * Create event description |
| 53 | */ |
| 54 | static |
| 55 | int lttng_create_ftrace_event(const char *name, struct ltt_event *event) |
| 56 | { |
| 57 | struct lttng_event_field *fields; |
| 58 | struct lttng_event_desc *desc; |
| 59 | int ret; |
| 60 | |
| 61 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); |
| 62 | if (!desc) |
| 63 | return -ENOMEM; |
| 64 | desc->name = kstrdup(name, GFP_KERNEL); |
| 65 | if (!desc->name) { |
| 66 | ret = -ENOMEM; |
| 67 | goto error_str; |
| 68 | } |
| 69 | desc->nr_fields = 2; |
| 70 | desc->fields = fields = |
| 71 | kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL); |
| 72 | fields[0].name = "ip"; |
| 73 | fields[0].type.atype = atype_integer; |
| 74 | fields[0].type.u.basic.integer.size = sizeof(unsigned long); |
| 75 | fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long); |
| 76 | fields[0].type.u.basic.integer.signedness = 0; |
| 77 | fields[0].type.u.basic.integer.reverse_byte_order = 0; |
| 78 | fields[0].type.u.basic.integer.base = 16; |
| 79 | fields[0].type.u.basic.integer.encoding = lttng_encode_none; |
| 80 | |
| 81 | fields[1].name = "parent_ip"; |
| 82 | fields[1].type.atype = atype_integer; |
| 83 | fields[1].type.u.basic.integer.size = sizeof(unsigned long); |
| 84 | fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long); |
| 85 | fields[1].type.u.basic.integer.signedness = 0; |
| 86 | fields[1].type.u.basic.integer.reverse_byte_order = 0; |
| 87 | fields[1].type.u.basic.integer.base = 16; |
| 88 | fields[1].type.u.basic.integer.encoding = lttng_encode_none; |
| 89 | |
| 90 | event->desc = desc; |
| 91 | |
| 92 | return 0; |
| 93 | |
| 94 | error_str: |
| 95 | kfree(desc); |
| 96 | return ret; |
| 97 | } |
| 98 | |
| 99 | static |
| 100 | struct ftrace_probe_ops lttng_ftrace_ops = { |
| 101 | .func = lttng_ftrace_handler, |
| 102 | }; |
| 103 | |
| 104 | int lttng_ftrace_register(const char *name, |
| 105 | const char *symbol_name, |
| 106 | struct ltt_event *event) |
| 107 | { |
| 108 | int ret; |
| 109 | |
| 110 | ret = lttng_create_ftrace_event(name, event); |
| 111 | if (ret) |
| 112 | goto error; |
| 113 | |
| 114 | event->u.ftrace.symbol_name = kstrdup(name, GFP_KERNEL); |
| 115 | if (!event->u.ftrace.symbol_name) |
| 116 | goto name_error; |
| 117 | |
| 118 | ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name, |
| 119 | <tng_ftrace_ops, event); |
| 120 | if (ret) |
| 121 | goto register_error; |
| 122 | return 0; |
| 123 | |
| 124 | register_error: |
| 125 | kfree(event->u.ftrace.symbol_name); |
| 126 | name_error: |
| 127 | kfree(event->desc->name); |
| 128 | kfree(event->desc); |
| 129 | error: |
| 130 | return ret; |
| 131 | } |
| 132 | EXPORT_SYMBOL_GPL(lttng_ftrace_register); |
| 133 | |
| 134 | void lttng_ftrace_unregister(struct ltt_event *event) |
| 135 | { |
| 136 | wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name, |
| 137 | <tng_ftrace_ops, event); |
| 138 | kfree(event->u.ftrace.symbol_name); |
| 139 | kfree(event->desc->name); |
| 140 | kfree(event->desc); |
| 141 | } |
| 142 | EXPORT_SYMBOL_GPL(lttng_ftrace_unregister); |
| 143 | |
| 144 | /* This module is permanent. */ |
| 145 | int lttng_ftrace_init(void) |
| 146 | { |
| 147 | return 0; |
| 148 | } |
| 149 | module_init(lttng_ftrace_init) |
| 150 | |
| 151 | MODULE_LICENSE("GPL and additional rights"); |
| 152 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 153 | MODULE_DESCRIPTION("Linux Trace Toolkit Ftrace Support"); |