| 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 <ringbuffer/frontend_types.h> |
| 15 | #include <wrapper/vmalloc.h> |
| 16 | #include <wrapper/irqflags.h> |
| 17 | #include <lttng/tracer.h> |
| 18 | #include <blacklist/kprobes.h> |
| 19 | |
| 20 | static |
| 21 | int lttng_kprobes_event_handler_pre(struct kprobe *p, struct pt_regs *regs) |
| 22 | { |
| 23 | struct lttng_event *event = |
| 24 | container_of(p, struct lttng_event, u.kprobe.kp); |
| 25 | struct lttng_probe_ctx lttng_probe_ctx = { |
| 26 | .event = event, |
| 27 | .interruptible = !lttng_regs_irqs_disabled(regs), |
| 28 | }; |
| 29 | struct lttng_channel *chan = event->chan; |
| 30 | struct lib_ring_buffer_ctx ctx; |
| 31 | int ret; |
| 32 | unsigned long data = (unsigned long) p->addr; |
| 33 | |
| 34 | if (unlikely(!LTTNG_READ_ONCE(chan->session->active))) |
| 35 | return 0; |
| 36 | if (unlikely(!LTTNG_READ_ONCE(chan->enabled))) |
| 37 | return 0; |
| 38 | if (unlikely(!LTTNG_READ_ONCE(event->enabled))) |
| 39 | return 0; |
| 40 | |
| 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); |
| 44 | if (ret < 0) |
| 45 | return 0; |
| 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); |
| 49 | return 0; |
| 50 | } |
| 51 | |
| 52 | static |
| 53 | int lttng_kprobes_event_notifier_handler_pre(struct kprobe *p, struct pt_regs *regs) |
| 54 | { |
| 55 | struct lttng_event_notifier *event_notifier = |
| 56 | container_of(p, struct lttng_event_notifier, u.kprobe.kp); |
| 57 | struct lttng_kernel_notifier_ctx notif_ctx; |
| 58 | |
| 59 | if (unlikely(!READ_ONCE(event_notifier->enabled))) |
| 60 | return 0; |
| 61 | |
| 62 | notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture); |
| 63 | event_notifier->send_notification(event_notifier, NULL, NULL, ¬if_ctx); |
| 64 | |
| 65 | return 0; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * Create event description |
| 70 | */ |
| 71 | static |
| 72 | int lttng_create_kprobe_event(const char *name, struct lttng_event *event) |
| 73 | { |
| 74 | struct lttng_event_field *field; |
| 75 | struct lttng_event_desc *desc; |
| 76 | int ret; |
| 77 | |
| 78 | desc = kzalloc(sizeof(*event->desc), GFP_KERNEL); |
| 79 | if (!desc) |
| 80 | return -ENOMEM; |
| 81 | desc->name = kstrdup(name, GFP_KERNEL); |
| 82 | if (!desc->name) { |
| 83 | ret = -ENOMEM; |
| 84 | goto error_str; |
| 85 | } |
| 86 | desc->nr_fields = 1; |
| 87 | desc->fields = field = |
| 88 | kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL); |
| 89 | if (!field) { |
| 90 | ret = -ENOMEM; |
| 91 | goto error_field; |
| 92 | } |
| 93 | field->name = "ip"; |
| 94 | field->type.atype = atype_integer; |
| 95 | field->type.u.integer.size = sizeof(unsigned long) * CHAR_BIT; |
| 96 | field->type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT; |
| 97 | field->type.u.integer.signedness = lttng_is_signed_type(unsigned long); |
| 98 | field->type.u.integer.reverse_byte_order = 0; |
| 99 | field->type.u.integer.base = 16; |
| 100 | field->type.u.integer.encoding = lttng_encode_none; |
| 101 | desc->owner = THIS_MODULE; |
| 102 | event->desc = desc; |
| 103 | |
| 104 | return 0; |
| 105 | |
| 106 | error_field: |
| 107 | kfree(desc->name); |
| 108 | error_str: |
| 109 | kfree(desc); |
| 110 | return ret; |
| 111 | } |
| 112 | |
| 113 | /* |
| 114 | * Create event_notifier description |
| 115 | */ |
| 116 | static |
| 117 | int lttng_create_kprobe_event_notifier(const char *name, struct lttng_event_notifier *event_notifier) |
| 118 | { |
| 119 | struct lttng_event_desc *desc; |
| 120 | int ret; |
| 121 | |
| 122 | desc = kzalloc(sizeof(*event_notifier->desc), GFP_KERNEL); |
| 123 | if (!desc) |
| 124 | return -ENOMEM; |
| 125 | desc->name = kstrdup(name, GFP_KERNEL); |
| 126 | if (!desc->name) { |
| 127 | ret = -ENOMEM; |
| 128 | goto error_str; |
| 129 | } |
| 130 | desc->nr_fields = 0; |
| 131 | |
| 132 | desc->owner = THIS_MODULE; |
| 133 | event_notifier->desc = desc; |
| 134 | |
| 135 | return 0; |
| 136 | |
| 137 | error_str: |
| 138 | kfree(desc); |
| 139 | return ret; |
| 140 | } |
| 141 | |
| 142 | static |
| 143 | int _lttng_kprobes_register(const char *symbol_name, |
| 144 | uint64_t offset, |
| 145 | uint64_t addr, |
| 146 | struct lttng_kprobe *lttng_kp, |
| 147 | kprobe_pre_handler_t pre_handler) |
| 148 | { |
| 149 | int ret; |
| 150 | |
| 151 | /* Kprobes expects a NULL symbol name if unused */ |
| 152 | if (symbol_name[0] == '\0') |
| 153 | symbol_name = NULL; |
| 154 | |
| 155 | memset(<tng_kp->kp, 0, sizeof(lttng_kp->kp)); |
| 156 | lttng_kp->kp.pre_handler = pre_handler; |
| 157 | |
| 158 | if (symbol_name) { |
| 159 | lttng_kp->symbol_name = |
| 160 | kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char), |
| 161 | GFP_KERNEL); |
| 162 | if (!lttng_kp->symbol_name) { |
| 163 | ret = -ENOMEM; |
| 164 | goto name_error; |
| 165 | } |
| 166 | memcpy(lttng_kp->symbol_name, symbol_name, |
| 167 | LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char)); |
| 168 | lttng_kp->kp.symbol_name = lttng_kp->symbol_name; |
| 169 | } |
| 170 | |
| 171 | lttng_kp->kp.offset = offset; |
| 172 | lttng_kp->kp.addr = (void *) (unsigned long) addr; |
| 173 | |
| 174 | /* |
| 175 | * Ensure the memory we just allocated don't event_notifier page faults. |
| 176 | * Well.. kprobes itself puts the page fault handler on the blacklist, |
| 177 | * but we can never be too careful. |
| 178 | */ |
| 179 | wrapper_vmalloc_sync_mappings(); |
| 180 | |
| 181 | ret = register_kprobe(<tng_kp->kp); |
| 182 | if (ret) |
| 183 | goto register_error; |
| 184 | |
| 185 | return 0; |
| 186 | |
| 187 | register_error: |
| 188 | kfree(lttng_kp->symbol_name); |
| 189 | name_error: |
| 190 | return ret; |
| 191 | } |
| 192 | |
| 193 | int lttng_kprobes_register_event(const char *name, |
| 194 | const char *symbol_name, |
| 195 | uint64_t offset, |
| 196 | uint64_t addr, |
| 197 | struct lttng_event *event) |
| 198 | { |
| 199 | int ret; |
| 200 | |
| 201 | ret = lttng_create_kprobe_event(name, event); |
| 202 | if (ret) |
| 203 | goto error; |
| 204 | |
| 205 | ret = _lttng_kprobes_register(symbol_name, offset, addr, |
| 206 | &event->u.kprobe, lttng_kprobes_event_handler_pre); |
| 207 | if (ret) |
| 208 | goto register_error; |
| 209 | |
| 210 | return 0; |
| 211 | |
| 212 | register_error: |
| 213 | kfree(event->desc->fields); |
| 214 | kfree(event->desc->name); |
| 215 | kfree(event->desc); |
| 216 | error: |
| 217 | return ret; |
| 218 | } |
| 219 | EXPORT_SYMBOL_GPL(lttng_kprobes_register_event); |
| 220 | |
| 221 | int lttng_kprobes_register_event_notifier(const char *symbol_name, |
| 222 | uint64_t offset, |
| 223 | uint64_t addr, |
| 224 | struct lttng_event_notifier *event_notifier) |
| 225 | { |
| 226 | int ret; |
| 227 | ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier); |
| 228 | if (ret) |
| 229 | goto error; |
| 230 | |
| 231 | ret = _lttng_kprobes_register(symbol_name, offset, addr, |
| 232 | &event_notifier->u.kprobe, lttng_kprobes_event_notifier_handler_pre); |
| 233 | if (ret) |
| 234 | goto register_error; |
| 235 | |
| 236 | return 0; |
| 237 | |
| 238 | register_error: |
| 239 | kfree(event_notifier->desc->name); |
| 240 | kfree(event_notifier->desc); |
| 241 | error: |
| 242 | return ret; |
| 243 | } |
| 244 | EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier); |
| 245 | |
| 246 | void lttng_kprobes_unregister_event(struct lttng_event *event) |
| 247 | { |
| 248 | unregister_kprobe(&event->u.kprobe.kp); |
| 249 | } |
| 250 | EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event); |
| 251 | |
| 252 | void lttng_kprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier) |
| 253 | { |
| 254 | unregister_kprobe(&event_notifier->u.kprobe.kp); |
| 255 | } |
| 256 | EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier); |
| 257 | |
| 258 | void lttng_kprobes_destroy_event_private(struct lttng_event *event) |
| 259 | { |
| 260 | kfree(event->u.kprobe.symbol_name); |
| 261 | kfree(event->desc->fields); |
| 262 | kfree(event->desc->name); |
| 263 | kfree(event->desc); |
| 264 | } |
| 265 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private); |
| 266 | |
| 267 | void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier) |
| 268 | { |
| 269 | kfree(event_notifier->u.kprobe.symbol_name); |
| 270 | kfree(event_notifier->desc->name); |
| 271 | kfree(event_notifier->desc); |
| 272 | } |
| 273 | EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private); |
| 274 | |
| 275 | MODULE_LICENSE("GPL and additional rights"); |
| 276 | MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>"); |
| 277 | MODULE_DESCRIPTION("LTTng kprobes probes"); |
| 278 | MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "." |
| 279 | __stringify(LTTNG_MODULES_MINOR_VERSION) "." |
| 280 | __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION) |
| 281 | LTTNG_MODULES_EXTRAVERSION); |