1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * probes/lttng-kprobes.c
5 * LTTng kprobes integration module.
7 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 #include <linux/module.h>
11 #include <linux/kprobes.h>
12 #include <linux/slab.h>
13 #include <lttng/events.h>
14 #include <ringbuffer/frontend_types.h>
15 #include <wrapper/vmalloc.h>
16 #include <wrapper/irqflags.h>
17 #include <lttng/tracer.h>
18 #include <blacklist/kprobes.h>
21 int lttng_kprobes_event_handler_pre(struct kprobe
*p
, struct pt_regs
*regs
)
23 struct lttng_event
*event
=
24 container_of(p
, struct lttng_event
, u
.kprobe
.kp
);
25 struct lttng_probe_ctx lttng_probe_ctx
= {
27 .interruptible
= !lttng_regs_irqs_disabled(regs
),
29 struct lttng_channel
*chan
= event
->chan
;
30 struct lib_ring_buffer_ctx ctx
;
32 unsigned long data
= (unsigned long) p
->addr
;
34 if (unlikely(!LTTNG_READ_ONCE(chan
->session
->active
)))
36 if (unlikely(!LTTNG_READ_ONCE(chan
->enabled
)))
38 if (unlikely(!LTTNG_READ_ONCE(event
->enabled
)))
41 lib_ring_buffer_ctx_init(&ctx
, chan
->chan
, <tng_probe_ctx
, sizeof(data
),
42 lttng_alignof(data
), -1);
43 ret
= chan
->ops
->event_reserve(&ctx
, event
->id
);
46 lib_ring_buffer_align_ctx(&ctx
, lttng_alignof(data
));
47 chan
->ops
->event_write(&ctx
, &data
, sizeof(data
));
48 chan
->ops
->event_commit(&ctx
);
53 * Create event description
56 int lttng_create_kprobe_event(const char *name
, struct lttng_event
*event
)
58 struct lttng_event_field
*field
;
59 struct lttng_event_desc
*desc
;
62 desc
= kzalloc(sizeof(*event
->desc
), GFP_KERNEL
);
65 desc
->name
= kstrdup(name
, GFP_KERNEL
);
71 desc
->fields
= field
=
72 kzalloc(1 * sizeof(struct lttng_event_field
), GFP_KERNEL
);
78 field
->type
.atype
= atype_integer
;
79 field
->type
.u
.integer
.size
= sizeof(unsigned long) * CHAR_BIT
;
80 field
->type
.u
.integer
.alignment
= lttng_alignof(unsigned long) * CHAR_BIT
;
81 field
->type
.u
.integer
.signedness
= lttng_is_signed_type(unsigned long);
82 field
->type
.u
.integer
.reverse_byte_order
= 0;
83 field
->type
.u
.integer
.base
= 16;
84 field
->type
.u
.integer
.encoding
= lttng_encode_none
;
85 desc
->owner
= THIS_MODULE
;
98 int _lttng_kprobes_register(const char *symbol_name
,
101 struct lttng_kprobe
*lttng_kp
,
102 kprobe_pre_handler_t pre_handler
)
106 /* Kprobes expects a NULL symbol name if unused */
107 if (symbol_name
[0] == '\0')
110 memset(<tng_kp
->kp
, 0, sizeof(lttng_kp
->kp
));
111 lttng_kp
->kp
.pre_handler
= pre_handler
;
114 lttng_kp
->symbol_name
=
115 kzalloc(LTTNG_KERNEL_SYM_NAME_LEN
* sizeof(char),
117 if (!lttng_kp
->symbol_name
) {
121 memcpy(lttng_kp
->symbol_name
, symbol_name
,
122 LTTNG_KERNEL_SYM_NAME_LEN
* sizeof(char));
123 lttng_kp
->kp
.symbol_name
= lttng_kp
->symbol_name
;
126 lttng_kp
->kp
.offset
= offset
;
127 lttng_kp
->kp
.addr
= (void *) (unsigned long) addr
;
130 * Ensure the memory we just allocated don't trigger page faults.
131 * Well.. kprobes itself puts the page fault handler on the blacklist,
132 * but we can never be too careful.
134 wrapper_vmalloc_sync_mappings();
136 ret
= register_kprobe(<tng_kp
->kp
);
143 kfree(lttng_kp
->symbol_name
);
148 int lttng_kprobes_register_event(const char *name
,
149 const char *symbol_name
,
152 struct lttng_event
*event
)
156 ret
= lttng_create_kprobe_event(name
, event
);
160 ret
= _lttng_kprobes_register(symbol_name
, offset
, addr
,
161 &event
->u
.kprobe
, lttng_kprobes_event_handler_pre
);
168 kfree(event
->desc
->fields
);
169 kfree(event
->desc
->name
);
174 EXPORT_SYMBOL_GPL(lttng_kprobes_register_event
);
176 void lttng_kprobes_unregister_event(struct lttng_event
*event
)
178 unregister_kprobe(&event
->u
.kprobe
.kp
);
180 EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event
);
182 void lttng_kprobes_destroy_event_private(struct lttng_event
*event
)
184 kfree(event
->u
.kprobe
.symbol_name
);
185 kfree(event
->desc
->fields
);
186 kfree(event
->desc
->name
);
189 EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private
);
191 MODULE_LICENSE("GPL and additional rights");
192 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
193 MODULE_DESCRIPTION("LTTng kprobes probes");
194 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION
) "."
195 __stringify(LTTNG_MODULES_MINOR_VERSION
) "."
196 __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION
)
197 LTTNG_MODULES_EXTRAVERSION
);