2 * probes/lttng-kprobes.c
4 * LTTng kprobes integration module.
6 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; only
11 * version 2.1 of the License.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include <linux/module.h>
24 #include <linux/kprobes.h>
25 #include <linux/slab.h>
26 #include "../lttng-events.h"
27 #include "../wrapper/ringbuffer/frontend_types.h"
28 #include "../wrapper/vmalloc.h"
29 #include "../lttng-tracer.h"
32 int lttng_kprobes_handler_pre(struct kprobe *p, struct pt_regs *regs)
34 struct lttng_event *event =
35 container_of(p, struct lttng_event, u.kprobe.kp);
36 struct lttng_channel *chan = event->chan;
37 struct lib_ring_buffer_ctx ctx;
39 unsigned long data = (unsigned long) p->addr;
41 if (unlikely(!ACCESS_ONCE(chan->session->active)))
43 if (unlikely(!ACCESS_ONCE(chan->enabled)))
45 if (unlikely(!ACCESS_ONCE(event->enabled)))
48 lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(data),
49 lttng_alignof(data), -1);
50 ret = chan->ops->event_reserve(&ctx, event->id);
53 lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
54 chan->ops->event_write(&ctx, &data, sizeof(data));
55 chan->ops->event_commit(&ctx);
60 * Create event description
63 int lttng_create_kprobe_event(const char *name, struct lttng_event *event)
65 struct lttng_event_field *field;
66 struct lttng_event_desc *desc;
69 desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
72 desc->name = kstrdup(name, GFP_KERNEL);
78 desc->fields = field =
79 kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
85 field->type.atype = atype_integer;
86 field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
87 field->type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
88 field->type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
89 field->type.u.basic.integer.reverse_byte_order = 0;
90 field->type.u.basic.integer.base = 16;
91 field->type.u.basic.integer.encoding = lttng_encode_none;
92 desc->owner = THIS_MODULE;
104 int lttng_kprobes_register(const char *name,
105 const char *symbol_name,
108 struct lttng_event *event)
112 /* Kprobes expects a NULL symbol name if unused */
113 if (symbol_name[0] == '\0')
116 ret = lttng_create_kprobe_event(name, event);
119 memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
120 event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
122 event->u.kprobe.symbol_name =
123 kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
125 if (!event->u.kprobe.symbol_name) {
129 memcpy(event->u.kprobe.symbol_name, symbol_name,
130 LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
131 event->u.kprobe.kp.symbol_name =
132 event->u.kprobe.symbol_name;
134 event->u.kprobe.kp.offset = offset;
135 event->u.kprobe.kp.addr = (void *) (unsigned long) addr;
138 * Ensure the memory we just allocated don't trigger page faults.
139 * Well.. kprobes itself puts the page fault handler on the blacklist,
140 * but we can never be too careful.
142 wrapper_vmalloc_sync_all();
144 ret = register_kprobe(&event->u.kprobe.kp);
150 kfree(event->u.kprobe.symbol_name);
152 kfree(event->desc->fields);
153 kfree(event->desc->name);
158 EXPORT_SYMBOL_GPL(lttng_kprobes_register);
160 void lttng_kprobes_unregister(struct lttng_event *event)
162 unregister_kprobe(&event->u.kprobe.kp);
164 EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
166 void lttng_kprobes_destroy_private(struct lttng_event *event)
168 kfree(event->u.kprobe.symbol_name);
169 kfree(event->desc->fields);
170 kfree(event->desc->name);
173 EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private);
175 MODULE_LICENSE("GPL and additional rights");
176 MODULE_AUTHOR("Mathieu Desnoyers");
177 MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");