| 1 | /* |
| 2 | * probes/lttng-kprobes.c |
| 3 | * |
| 4 | * LTTng kprobes integration module. |
| 5 | * |
| 6 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 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. |
| 12 | * |
| 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. |
| 17 | * |
| 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 |
| 21 | */ |
| 22 | |
| 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 <wrapper/irqflags.h> |
| 30 | #include <lttng-tracer.h> |
| 31 | |
| 32 | static |
| 33 | int lttng_kprobes_handler_pre(struct kprobe *p, struct pt_regs *regs) |
| 34 | { |
| 35 | struct lttng_event *event = |
| 36 | container_of(p, struct lttng_event, u.kprobe.kp); |
| 37 | struct lttng_probe_ctx lttng_probe_ctx = { |
| 38 | .event = event, |
| 39 | .interruptible = !lttng_regs_irqs_disabled(regs), |
| 40 | }; |
| 41 | struct lttng_channel *chan = event->chan; |
| 42 | struct lib_ring_buffer_ctx ctx; |
| 43 | int ret; |
| 44 | unsigned long data = (unsigned long) p->addr; |
| 45 | |
| 46 | if (unlikely(!ACCESS_ONCE(chan->session->active))) |
| 47 | return 0; |
| 48 | if (unlikely(!ACCESS_ONCE(chan->enabled))) |
| 49 | return 0; |
| 50 | if (unlikely(!ACCESS_ONCE(event->enabled))) |
| 51 | return 0; |
| 52 | |
| 53 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(data), |
| 54 | lttng_alignof(data), -1); |
| 55 | ret = chan->ops->event_reserve(&ctx, event->id); |
| 56 | if (ret < 0) |
| 57 | return 0; |
| 58 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data)); |
| 59 | chan->ops->event_write(&ctx, &data, sizeof(data)); |
| 60 | chan->ops->event_commit(&ctx); |
| 61 | return 0; |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * Create event description |
| 66 | */ |
| 67 | static |
| 68 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event) |
| 69 | { |
| 70 | struct lttng_event_field *field; |
| 71 | struct lttng_event_desc *desc; |
| 72 | int ret; |
| 73 | |
| 74 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); |
| 75 | if (!desc) |
| 76 | return -ENOMEM; |
| 77 | desc->name = kstrdup(name, GFP_KERNEL); |
| 78 | if (!desc->name) { |
| 79 | ret = -ENOMEM; |
| 80 | goto error_str; |
| 81 | } |
| 82 | desc->nr_fields = 1; |
| 83 | desc->fields = field = |
| 84 | kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL); |
| 85 | if (!field) { |
| 86 | ret = -ENOMEM; |
| 87 | goto error_field; |
| 88 | } |
| 89 | field->name = "ip"; |
| 90 | field->type.atype = atype_integer; |
| 91 | field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT; |
| 92 | field->type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; |
| 93 | field->type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long); |
| 94 | field->type.u.basic.integer.reverse_byte_order = 0; |
| 95 | field->type.u.basic.integer.base = 16; |
| 96 | field->type.u.basic.integer.encoding = lttng_encode_none; |
| 97 | desc->owner = THIS_MODULE; |
| 98 | event->desc = desc; |
| 99 | |
| 100 | return 0; |
| 101 | |
| 102 | error_field: |
| 103 | kfree(desc->name); |
| 104 | error_str: |
| 105 | kfree(desc); |
| 106 | return ret; |
| 107 | } |
| 108 | |
| 109 | int lttng_kprobes_register(const char *name, |
| 110 | const char *symbol_name, |
| 111 | uint64_t offset, |
| 112 | uint64_t addr, |
| 113 | struct lttng_event *event) |
| 114 | { |
| 115 | int ret; |
| 116 | |
| 117 | /* Kprobes expects a NULL symbol name if unused */ |
| 118 | if (symbol_name[0] == '\0') |
| 119 | symbol_name = NULL; |
| 120 | |
| 121 | ret = lttng_create_kprobe_event(name, event); |
| 122 | if (ret) |
| 123 | goto error; |
| 124 | memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp)); |
| 125 | event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre; |
| 126 | if (symbol_name) { |
| 127 | event->u.kprobe.symbol_name = |
| 128 | kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char), |
| 129 | GFP_KERNEL); |
| 130 | if (!event->u.kprobe.symbol_name) { |
| 131 | ret = -ENOMEM; |
| 132 | goto name_error; |
| 133 | } |
| 134 | memcpy(event->u.kprobe.symbol_name, symbol_name, |
| 135 | LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char)); |
| 136 | event->u.kprobe.kp.symbol_name = |
| 137 | event->u.kprobe.symbol_name; |
| 138 | } |
| 139 | event->u.kprobe.kp.offset = offset; |
| 140 | event->u.kprobe.kp.addr = (void *) (unsigned long) addr; |
| 141 | |
| 142 | /* |
| 143 | * Ensure the memory we just allocated don't trigger page faults. |
| 144 | * Well.. kprobes itself puts the page fault handler on the blacklist, |
| 145 | * but we can never be too careful. |
| 146 | */ |
| 147 | wrapper_vmalloc_sync_all(); |
| 148 | |
| 149 | ret = register_kprobe(&event->u.kprobe.kp); |
| 150 | if (ret) |
| 151 | goto register_error; |
| 152 | return 0; |
| 153 | |
| 154 | register_error: |
| 155 | kfree(event->u.kprobe.symbol_name); |
| 156 | name_error: |
| 157 | kfree(event->desc->fields); |
| 158 | kfree(event->desc->name); |
| 159 | kfree(event->desc); |
| 160 | error: |
| 161 | return ret; |
| 162 | } |
| 163 | EXPORT_SYMBOL_GPL(lttng_kprobes_register); |
| 164 | |
| 165 | void lttng_kprobes_unregister(struct lttng_event *event) |
| 166 | { |
| 167 | unregister_kprobe(&event->u.kprobe.kp); |
| 168 | } |
| 169 | EXPORT_SYMBOL_GPL(lttng_kprobes_unregister); |
| 170 | |
| 171 | void lttng_kprobes_destroy_private(struct lttng_event *event) |
| 172 | { |
| 173 | kfree(event->u.kprobe.symbol_name); |
| 174 | kfree(event->desc->fields); |
| 175 | kfree(event->desc->name); |
| 176 | kfree(event->desc); |
| 177 | } |
| 178 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private); |
| 179 | |
| 180 | MODULE_LICENSE("GPL and additional rights"); |
| 181 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 182 | MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support"); |
| 183 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
| 184 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." |
| 185 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) |
| 186 | LTTNG_MODULES_EXTRAVERSION); |