| 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 2 | * |
| 3 | * probes/lttng-kprobes.c |
| 4 | * |
| 5 | * LTTng kprobes integration module. |
| 6 | * |
| 7 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/kprobes.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <lttng/events.h> |
| 14 | #include <lttng/events-internal.h> |
| 15 | #include <ringbuffer/frontend_types.h> |
| 16 | #include <wrapper/vmalloc.h> |
| 17 | #include <wrapper/irqflags.h> |
| 18 | #include <lttng/tracer.h> |
| 19 | #include <blacklist/kprobes.h> |
| 20 | |
| 21 | static |
| 22 | int lttng_kprobes_event_handler_pre(struct kprobe *p, struct pt_regs *regs) |
| 23 | { |
| 24 | struct lttng_kernel_event_common_private *event_priv = |
| 25 | container_of(p, struct lttng_kernel_event_common_private, u.kprobe.kp); |
| 26 | struct lttng_kernel_event_common *event = event_priv->pub; |
| 27 | struct lttng_kernel_probe_ctx lttng_probe_ctx = { |
| 28 | .event = event, |
| 29 | .interruptible = !lttng_regs_irqs_disabled(regs), |
| 30 | }; |
| 31 | unsigned long data = (unsigned long) p->addr; |
| 32 | |
| 33 | switch (event->type) { |
| 34 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: |
| 35 | { |
| 36 | struct lttng_kernel_event_recorder_private *event_recorder_priv = |
| 37 | container_of(event_priv, struct lttng_kernel_event_recorder_private, parent); |
| 38 | struct lttng_kernel_event_recorder *event_recorder = |
| 39 | event_recorder_priv->pub; |
| 40 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
| 41 | |
| 42 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active))) |
| 43 | return 0; |
| 44 | if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled))) |
| 45 | return 0; |
| 46 | break; |
| 47 | } |
| 48 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: |
| 49 | break; |
| 50 | default: |
| 51 | WARN_ON_ONCE(1); |
| 52 | } |
| 53 | |
| 54 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
| 55 | return 0; |
| 56 | |
| 57 | switch (event->type) { |
| 58 | case LTTNG_KERNEL_EVENT_TYPE_RECORDER: |
| 59 | { |
| 60 | struct lttng_kernel_event_recorder *event_recorder = |
| 61 | container_of(event, struct lttng_kernel_event_recorder, parent); |
| 62 | struct lttng_kernel_channel_buffer *chan = event_recorder->chan; |
| 63 | struct lttng_kernel_ring_buffer_ctx ctx; |
| 64 | int ret; |
| 65 | |
| 66 | lib_ring_buffer_ctx_init(&ctx, event_recorder, sizeof(data), |
| 67 | lttng_alignof(data), <tng_probe_ctx); |
| 68 | ret = chan->ops->event_reserve(&ctx); |
| 69 | if (ret < 0) |
| 70 | return 0; |
| 71 | chan->ops->event_write(&ctx, &data, sizeof(data), lttng_alignof(data)); |
| 72 | chan->ops->event_commit(&ctx); |
| 73 | break; |
| 74 | } |
| 75 | case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER: |
| 76 | { |
| 77 | struct lttng_kernel_event_notifier *event_notifier = |
| 78 | container_of(event, struct lttng_kernel_event_notifier, parent); |
| 79 | struct lttng_kernel_notification_ctx notif_ctx; |
| 80 | |
| 81 | notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture); |
| 82 | event_notifier->notification_send(event_notifier, NULL, NULL, ¬if_ctx); |
| 83 | break; |
| 84 | } |
| 85 | default: |
| 86 | WARN_ON_ONCE(1); |
| 87 | } |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | static const struct lttng_kernel_event_field *event_fields[] = { |
| 92 | lttng_kernel_static_event_field("ip", |
| 93 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16), |
| 94 | false, false, false), |
| 95 | }; |
| 96 | |
| 97 | static const struct lttng_kernel_tracepoint_class tp_class = { |
| 98 | .nr_fields = ARRAY_SIZE(event_fields), |
| 99 | .fields = event_fields, |
| 100 | }; |
| 101 | |
| 102 | /* |
| 103 | * Create event description |
| 104 | */ |
| 105 | static |
| 106 | int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder) |
| 107 | { |
| 108 | struct lttng_kernel_event_desc *desc; |
| 109 | int ret; |
| 110 | |
| 111 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
| 112 | if (!desc) |
| 113 | return -ENOMEM; |
| 114 | desc->tp_class = &tp_class; |
| 115 | desc->event_name = kstrdup(name, GFP_KERNEL); |
| 116 | if (!desc->event_name) { |
| 117 | ret = -ENOMEM; |
| 118 | goto error_str; |
| 119 | } |
| 120 | desc->owner = THIS_MODULE; |
| 121 | event_recorder->priv->parent.desc = desc; |
| 122 | |
| 123 | return 0; |
| 124 | |
| 125 | error_str: |
| 126 | kfree(desc); |
| 127 | return ret; |
| 128 | } |
| 129 | |
| 130 | /* |
| 131 | * Create event_notifier description |
| 132 | */ |
| 133 | static |
| 134 | int lttng_create_kprobe_event_notifier(const char *name, struct lttng_kernel_event_notifier *event_notifier) |
| 135 | { |
| 136 | struct lttng_kernel_event_desc *desc; |
| 137 | int ret; |
| 138 | |
| 139 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
| 140 | if (!desc) |
| 141 | return -ENOMEM; |
| 142 | desc->tp_class = &tp_class; |
| 143 | desc->event_name = kstrdup(name, GFP_KERNEL); |
| 144 | if (!desc->event_name) { |
| 145 | ret = -ENOMEM; |
| 146 | goto error_str; |
| 147 | } |
| 148 | desc->owner = THIS_MODULE; |
| 149 | event_notifier->priv->parent.desc = desc; |
| 150 | |
| 151 | return 0; |
| 152 | |
| 153 | error_str: |
| 154 | kfree(desc); |
| 155 | return ret; |
| 156 | } |
| 157 | |
| 158 | static |
| 159 | int _lttng_kprobes_register(const char *symbol_name, |
| 160 | uint64_t offset, |
| 161 | uint64_t addr, |
| 162 | struct lttng_kprobe *lttng_kp, |
| 163 | kprobe_pre_handler_t pre_handler) |
| 164 | { |
| 165 | int ret; |
| 166 | |
| 167 | /* Kprobes expects a NULL symbol name if unused */ |
| 168 | if (symbol_name[0] == '\0') |
| 169 | symbol_name = NULL; |
| 170 | |
| 171 | memset(<tng_kp->kp, 0, sizeof(lttng_kp->kp)); |
| 172 | lttng_kp->kp.pre_handler = pre_handler; |
| 173 | |
| 174 | if (symbol_name) { |
| 175 | lttng_kp->symbol_name = |
| 176 | kzalloc(LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char), |
| 177 | GFP_KERNEL); |
| 178 | if (!lttng_kp->symbol_name) { |
| 179 | ret = -ENOMEM; |
| 180 | goto name_error; |
| 181 | } |
| 182 | memcpy(lttng_kp->symbol_name, symbol_name, |
| 183 | LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char)); |
| 184 | lttng_kp->kp.symbol_name = lttng_kp->symbol_name; |
| 185 | } |
| 186 | |
| 187 | lttng_kp->kp.offset = offset; |
| 188 | lttng_kp->kp.addr = (void *) (unsigned long) addr; |
| 189 | |
| 190 | /* |
| 191 | * Ensure the memory we just allocated don't notify page faults. |
| 192 | * Well.. kprobes itself puts the page fault handler on the blacklist, |
| 193 | * but we can never be too careful. |
| 194 | */ |
| 195 | wrapper_vmalloc_sync_mappings(); |
| 196 | |
| 197 | ret = register_kprobe(<tng_kp->kp); |
| 198 | if (ret) |
| 199 | goto register_error; |
| 200 | |
| 201 | return 0; |
| 202 | |
| 203 | register_error: |
| 204 | kfree(lttng_kp->symbol_name); |
| 205 | name_error: |
| 206 | return ret; |
| 207 | } |
| 208 | |
| 209 | int lttng_kprobes_register_event(const char *name, |
| 210 | const char *symbol_name, |
| 211 | uint64_t offset, |
| 212 | uint64_t addr, |
| 213 | struct lttng_kernel_event_recorder *event_recorder) |
| 214 | { |
| 215 | int ret; |
| 216 | |
| 217 | ret = lttng_create_kprobe_event(name, event_recorder); |
| 218 | if (ret) |
| 219 | goto error; |
| 220 | |
| 221 | ret = _lttng_kprobes_register(symbol_name, offset, addr, |
| 222 | &event_recorder->priv->parent.u.kprobe, lttng_kprobes_event_handler_pre); |
| 223 | if (ret) |
| 224 | goto register_error; |
| 225 | |
| 226 | return 0; |
| 227 | |
| 228 | register_error: |
| 229 | kfree(event_recorder->priv->parent.desc->event_name); |
| 230 | kfree(event_recorder->priv->parent.desc); |
| 231 | error: |
| 232 | return ret; |
| 233 | } |
| 234 | EXPORT_SYMBOL_GPL(lttng_kprobes_register_event); |
| 235 | |
| 236 | int lttng_kprobes_register_event_notifier(const char *symbol_name, |
| 237 | uint64_t offset, |
| 238 | uint64_t addr, |
| 239 | struct lttng_kernel_event_notifier *event_notifier) |
| 240 | { |
| 241 | int ret; |
| 242 | ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier); |
| 243 | if (ret) |
| 244 | goto error; |
| 245 | |
| 246 | ret = _lttng_kprobes_register(symbol_name, offset, addr, |
| 247 | &event_notifier->priv->parent.u.kprobe, lttng_kprobes_event_handler_pre); |
| 248 | if (ret) |
| 249 | goto register_error; |
| 250 | |
| 251 | return 0; |
| 252 | |
| 253 | register_error: |
| 254 | kfree(event_notifier->priv->parent.desc->event_name); |
| 255 | kfree(event_notifier->priv->parent.desc); |
| 256 | error: |
| 257 | return ret; |
| 258 | } |
| 259 | EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier); |
| 260 | |
| 261 | void lttng_kprobes_unregister_event(struct lttng_kernel_event_recorder *event_recorder) |
| 262 | { |
| 263 | unregister_kprobe(&event_recorder->priv->parent.u.kprobe.kp); |
| 264 | } |
| 265 | EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event); |
| 266 | |
| 267 | void lttng_kprobes_unregister_event_notifier(struct lttng_kernel_event_notifier *event_notifier) |
| 268 | { |
| 269 | unregister_kprobe(&event_notifier->priv->parent.u.kprobe.kp); |
| 270 | } |
| 271 | EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier); |
| 272 | |
| 273 | void lttng_kprobes_destroy_event_private(struct lttng_kernel_event_recorder *event_recorder) |
| 274 | { |
| 275 | kfree(event_recorder->priv->parent.u.kprobe.symbol_name); |
| 276 | kfree(event_recorder->priv->parent.desc->event_name); |
| 277 | kfree(event_recorder->priv->parent.desc); |
| 278 | } |
| 279 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private); |
| 280 | |
| 281 | void lttng_kprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier) |
| 282 | { |
| 283 | kfree(event_notifier->priv->parent.u.kprobe.symbol_name); |
| 284 | kfree(event_notifier->priv->parent.desc->event_name); |
| 285 | kfree(event_notifier->priv->parent.desc); |
| 286 | } |
| 287 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private); |
| 288 | |
| 289 | MODULE_LICENSE("GPL and additional rights"); |
| 290 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
| 291 | MODULE_DESCRIPTION("LTTng kprobes probes"); |
| 292 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
| 293 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." |
| 294 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) |
| 295 | LTTNG_MODULES_EXTRAVERSION); |