| 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_recorder_private *event_recorder_priv = |
| 27 | container_of(event_priv, struct lttng_kernel_event_recorder_private, parent); |
| 28 | struct lttng_kernel_event_recorder *event_recorder = |
| 29 | event_recorder_priv->pub; |
| 30 | struct lttng_probe_ctx lttng_probe_ctx = { |
| 31 | .event = event_recorder, |
| 32 | .interruptible = !lttng_regs_irqs_disabled(regs), |
| 33 | }; |
| 34 | struct lttng_channel *chan = event_recorder->chan; |
| 35 | struct lib_ring_buffer_ctx ctx; |
| 36 | int ret; |
| 37 | unsigned long data = (unsigned long) p->addr; |
| 38 | |
| 39 | if (unlikely(!LTTNG_READ_ONCE(chan->session->active))) |
| 40 | return 0; |
| 41 | if (unlikely(!LTTNG_READ_ONCE(chan->enabled))) |
| 42 | return 0; |
| 43 | if (unlikely(!LTTNG_READ_ONCE(event_recorder->parent.enabled))) |
| 44 | return 0; |
| 45 | |
| 46 | lib_ring_buffer_ctx_init(&ctx, chan->chan, <tng_probe_ctx, sizeof(data), |
| 47 | lttng_alignof(data), -1); |
| 48 | ret = chan->ops->event_reserve(&ctx, event_recorder->priv->id); |
| 49 | if (ret < 0) |
| 50 | return 0; |
| 51 | lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data)); |
| 52 | chan->ops->event_write(&ctx, &data, sizeof(data)); |
| 53 | chan->ops->event_commit(&ctx); |
| 54 | return 0; |
| 55 | } |
| 56 | |
| 57 | static |
| 58 | int lttng_kprobes_event_notifier_handler_pre(struct kprobe *p, struct pt_regs *regs) |
| 59 | { |
| 60 | struct lttng_kernel_event_common_private *event_priv = |
| 61 | container_of(p, struct lttng_kernel_event_common_private, u.kprobe.kp); |
| 62 | struct lttng_kernel_event_notifier_private *event_notifier_priv = |
| 63 | container_of(event_priv, struct lttng_kernel_event_notifier_private, parent); |
| 64 | struct lttng_kernel_event_notifier *event_notifier = |
| 65 | event_notifier_priv->pub; |
| 66 | struct lttng_kernel_notification_ctx notif_ctx; |
| 67 | |
| 68 | if (unlikely(!READ_ONCE(event_notifier->parent.enabled))) |
| 69 | return 0; |
| 70 | |
| 71 | notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture); |
| 72 | event_notifier->notification_send(event_notifier, NULL, NULL, ¬if_ctx); |
| 73 | |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | static const struct lttng_kernel_type_common *event_type = |
| 78 | lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16); |
| 79 | |
| 80 | /* |
| 81 | * Create event description |
| 82 | */ |
| 83 | static |
| 84 | int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder) |
| 85 | { |
| 86 | const struct lttng_kernel_event_field **fieldp_array; |
| 87 | struct lttng_kernel_event_field *field; |
| 88 | struct lttng_kernel_event_desc *desc; |
| 89 | int ret; |
| 90 | |
| 91 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
| 92 | if (!desc) |
| 93 | return -ENOMEM; |
| 94 | desc->event_name = kstrdup(name, GFP_KERNEL); |
| 95 | if (!desc->event_name) { |
| 96 | ret = -ENOMEM; |
| 97 | goto error_str; |
| 98 | } |
| 99 | desc->nr_fields = 1; |
| 100 | fieldp_array = kzalloc(1 * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL); |
| 101 | if (!fieldp_array) { |
| 102 | ret = -ENOMEM; |
| 103 | goto error_fieldp_array; |
| 104 | } |
| 105 | desc->fields = fieldp_array; |
| 106 | desc->fields[0] = field = |
| 107 | kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL); |
| 108 | if (!field) { |
| 109 | ret = -ENOMEM; |
| 110 | goto error_field; |
| 111 | } |
| 112 | field->name = "ip"; |
| 113 | field->type = event_type; |
| 114 | desc->owner = THIS_MODULE; |
| 115 | event_recorder->priv->parent.desc = desc; |
| 116 | |
| 117 | return 0; |
| 118 | |
| 119 | error_field: |
| 120 | kfree(fieldp_array); |
| 121 | error_fieldp_array: |
| 122 | kfree(desc->event_name); |
| 123 | error_str: |
| 124 | kfree(desc); |
| 125 | return ret; |
| 126 | } |
| 127 | |
| 128 | /* |
| 129 | * Create event_notifier description |
| 130 | */ |
| 131 | static |
| 132 | int lttng_create_kprobe_event_notifier(const char *name, struct lttng_kernel_event_notifier *event_notifier) |
| 133 | { |
| 134 | struct lttng_kernel_event_desc *desc; |
| 135 | int ret; |
| 136 | |
| 137 | desc = kzalloc(sizeof(*desc), GFP_KERNEL); |
| 138 | if (!desc) |
| 139 | return -ENOMEM; |
| 140 | desc->event_name = kstrdup(name, GFP_KERNEL); |
| 141 | if (!desc->event_name) { |
| 142 | ret = -ENOMEM; |
| 143 | goto error_str; |
| 144 | } |
| 145 | desc->nr_fields = 0; |
| 146 | |
| 147 | desc->owner = THIS_MODULE; |
| 148 | event_notifier->priv->parent.desc = desc; |
| 149 | |
| 150 | return 0; |
| 151 | |
| 152 | error_str: |
| 153 | kfree(desc); |
| 154 | return ret; |
| 155 | } |
| 156 | |
| 157 | static |
| 158 | int _lttng_kprobes_register(const char *symbol_name, |
| 159 | uint64_t offset, |
| 160 | uint64_t addr, |
| 161 | struct lttng_kprobe *lttng_kp, |
| 162 | kprobe_pre_handler_t pre_handler) |
| 163 | { |
| 164 | int ret; |
| 165 | |
| 166 | /* Kprobes expects a NULL symbol name if unused */ |
| 167 | if (symbol_name[0] == '\0') |
| 168 | symbol_name = NULL; |
| 169 | |
| 170 | memset(<tng_kp->kp, 0, sizeof(lttng_kp->kp)); |
| 171 | lttng_kp->kp.pre_handler = pre_handler; |
| 172 | |
| 173 | if (symbol_name) { |
| 174 | lttng_kp->symbol_name = |
| 175 | kzalloc(LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char), |
| 176 | GFP_KERNEL); |
| 177 | if (!lttng_kp->symbol_name) { |
| 178 | ret = -ENOMEM; |
| 179 | goto name_error; |
| 180 | } |
| 181 | memcpy(lttng_kp->symbol_name, symbol_name, |
| 182 | LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char)); |
| 183 | lttng_kp->kp.symbol_name = lttng_kp->symbol_name; |
| 184 | } |
| 185 | |
| 186 | lttng_kp->kp.offset = offset; |
| 187 | lttng_kp->kp.addr = (void *) (unsigned long) addr; |
| 188 | |
| 189 | /* |
| 190 | * Ensure the memory we just allocated don't notify page faults. |
| 191 | * Well.. kprobes itself puts the page fault handler on the blacklist, |
| 192 | * but we can never be too careful. |
| 193 | */ |
| 194 | wrapper_vmalloc_sync_mappings(); |
| 195 | |
| 196 | ret = register_kprobe(<tng_kp->kp); |
| 197 | if (ret) |
| 198 | goto register_error; |
| 199 | |
| 200 | return 0; |
| 201 | |
| 202 | register_error: |
| 203 | kfree(lttng_kp->symbol_name); |
| 204 | name_error: |
| 205 | return ret; |
| 206 | } |
| 207 | |
| 208 | int lttng_kprobes_register_event(const char *name, |
| 209 | const char *symbol_name, |
| 210 | uint64_t offset, |
| 211 | uint64_t addr, |
| 212 | struct lttng_kernel_event_recorder *event_recorder) |
| 213 | { |
| 214 | int ret; |
| 215 | |
| 216 | ret = lttng_create_kprobe_event(name, event_recorder); |
| 217 | if (ret) |
| 218 | goto error; |
| 219 | |
| 220 | ret = _lttng_kprobes_register(symbol_name, offset, addr, |
| 221 | &event_recorder->priv->parent.u.kprobe, lttng_kprobes_event_handler_pre); |
| 222 | if (ret) |
| 223 | goto register_error; |
| 224 | |
| 225 | return 0; |
| 226 | |
| 227 | register_error: |
| 228 | kfree(event_recorder->priv->parent.desc->fields); |
| 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_notifier_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->fields[0]); |
| 277 | kfree(event_recorder->priv->parent.desc->fields); |
| 278 | kfree(event_recorder->priv->parent.desc->event_name); |
| 279 | kfree(event_recorder->priv->parent.desc); |
| 280 | } |
| 281 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private); |
| 282 | |
| 283 | void lttng_kprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier) |
| 284 | { |
| 285 | kfree(event_notifier->priv->parent.u.kprobe.symbol_name); |
| 286 | kfree(event_notifier->priv->parent.desc->event_name); |
| 287 | kfree(event_notifier->priv->parent.desc); |
| 288 | } |
| 289 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private); |
| 290 | |
| 291 | MODULE_LICENSE("GPL and additional rights"); |
| 292 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
| 293 | MODULE_DESCRIPTION("LTTng kprobes probes"); |
| 294 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
| 295 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." |
| 296 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) |
| 297 | LTTNG_MODULES_EXTRAVERSION); |