src/probes/lttng-kprobes.c

   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_channel *chan = event_recorder->chan;
  41
  42                 if (unlikely(!LTTNG_READ_ONCE(chan->session->active)))
  43                         return 0;
  44                 if (unlikely(!LTTNG_READ_ONCE(chan->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_channel *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), &lttng_probe_ctx);
  68                 ret = chan->ops->event_reserve(&ctx);
  69                 if (ret < 0)
  70                         return 0;
  71                 lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
  72                 chan->ops->event_write(&ctx, &data, sizeof(data));
  73                 chan->ops->event_commit(&ctx);
  74                 break;
  75         }
  76         case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
  77         {
  78                 struct lttng_kernel_event_notifier *event_notifier =
  79                         container_of(event, struct lttng_kernel_event_notifier, parent);
  80                 struct lttng_kernel_notification_ctx notif_ctx;
  81
  82                 notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
  83                 event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
  84                 break;
  85         }
  86         default:
  87                 WARN_ON_ONCE(1);
  88         }
  89         return 0;
  90 }
  91
  92 static const struct lttng_kernel_type_common *event_type =
  93         lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16);
  94
  95 /*
  96  * Create event description
  97  */
  98 static
  99 int lttng_create_kprobe_event(const char *name, struct lttng_kernel_event_recorder *event_recorder)
 100 {
 101         const struct lttng_kernel_event_field **fieldp_array;
 102         struct lttng_kernel_event_field *field;
 103         struct lttng_kernel_event_desc *desc;
 104         int ret;
 105
 106         desc = kzalloc(sizeof(*desc), GFP_KERNEL);
 107         if (!desc)
 108                 return -ENOMEM;
 109         desc->event_name = kstrdup(name, GFP_KERNEL);
 110         if (!desc->event_name) {
 111                 ret = -ENOMEM;
 112                 goto error_str;
 113         }
 114         desc->nr_fields = 1;
 115         fieldp_array = kzalloc(1 * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL);
 116         if (!fieldp_array) {
 117                 ret = -ENOMEM;
 118                 goto error_fieldp_array;
 119         }
 120         desc->fields = fieldp_array;
 121         desc->fields[0] = field =
 122                 kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL);
 123         if (!field) {
 124                 ret = -ENOMEM;
 125                 goto error_field;
 126         }
 127         field->name = "ip";
 128         field->type = event_type;
 129         desc->owner = THIS_MODULE;
 130         event_recorder->priv->parent.desc = desc;
 131
 132         return 0;
 133
 134 error_field:
 135         kfree(fieldp_array);
 136 error_fieldp_array:
 137         kfree(desc->event_name);
 138 error_str:
 139         kfree(desc);
 140         return ret;
 141 }
 142
 143 /*
 144  * Create event_notifier description
 145  */
 146 static
 147 int lttng_create_kprobe_event_notifier(const char *name, struct lttng_kernel_event_notifier *event_notifier)
 148 {
 149         struct lttng_kernel_event_desc *desc;
 150         int ret;
 151
 152         desc = kzalloc(sizeof(*desc), GFP_KERNEL);
 153         if (!desc)
 154                 return -ENOMEM;
 155         desc->event_name = kstrdup(name, GFP_KERNEL);
 156         if (!desc->event_name) {
 157                 ret = -ENOMEM;
 158                 goto error_str;
 159         }
 160         desc->nr_fields = 0;
 161
 162         desc->owner = THIS_MODULE;
 163         event_notifier->priv->parent.desc = desc;
 164
 165         return 0;
 166
 167 error_str:
 168         kfree(desc);
 169         return ret;
 170 }
 171
 172 static
 173 int _lttng_kprobes_register(const char *symbol_name,
 174                            uint64_t offset,
 175                            uint64_t addr,
 176                            struct lttng_kprobe *lttng_kp,
 177                            kprobe_pre_handler_t pre_handler)
 178 {
 179         int ret;
 180
 181         /* Kprobes expects a NULL symbol name if unused */
 182         if (symbol_name[0] == '\0')
 183                 symbol_name = NULL;
 184
 185         memset(&lttng_kp->kp, 0, sizeof(lttng_kp->kp));
 186         lttng_kp->kp.pre_handler = pre_handler;
 187
 188         if (symbol_name) {
 189                 lttng_kp->symbol_name =
 190                         kzalloc(LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char),
 191                                 GFP_KERNEL);
 192                 if (!lttng_kp->symbol_name) {
 193                         ret = -ENOMEM;
 194                         goto name_error;
 195                 }
 196                 memcpy(lttng_kp->symbol_name, symbol_name,
 197                        LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char));
 198                 lttng_kp->kp.symbol_name = lttng_kp->symbol_name;
 199         }
 200
 201         lttng_kp->kp.offset = offset;
 202         lttng_kp->kp.addr = (void *) (unsigned long) addr;
 203
 204         /*
 205          * Ensure the memory we just allocated don't notify page faults.
 206          * Well.. kprobes itself puts the page fault handler on the blacklist,
 207          * but we can never be too careful.
 208          */
 209         wrapper_vmalloc_sync_mappings();
 210
 211         ret = register_kprobe(&lttng_kp->kp);
 212         if (ret)
 213                 goto register_error;
 214
 215         return 0;
 216
 217 register_error:
 218         kfree(lttng_kp->symbol_name);
 219 name_error:
 220         return ret;
 221 }
 222
 223 int lttng_kprobes_register_event(const char *name,
 224                            const char *symbol_name,
 225                            uint64_t offset,
 226                            uint64_t addr,
 227                            struct lttng_kernel_event_recorder *event_recorder)
 228 {
 229         int ret;
 230
 231         ret = lttng_create_kprobe_event(name, event_recorder);
 232         if (ret)
 233                 goto error;
 234
 235         ret = _lttng_kprobes_register(symbol_name, offset, addr,
 236                 &event_recorder->priv->parent.u.kprobe, lttng_kprobes_event_handler_pre);
 237         if (ret)
 238                 goto register_error;
 239
 240         return 0;
 241
 242 register_error:
 243         kfree(event_recorder->priv->parent.desc->fields);
 244         kfree(event_recorder->priv->parent.desc->event_name);
 245         kfree(event_recorder->priv->parent.desc);
 246 error:
 247         return ret;
 248 }
 249 EXPORT_SYMBOL_GPL(lttng_kprobes_register_event);
 250
 251 int lttng_kprobes_register_event_notifier(const char *symbol_name,
 252                            uint64_t offset,
 253                            uint64_t addr,
 254                            struct lttng_kernel_event_notifier *event_notifier)
 255 {
 256         int ret;
 257         ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier);
 258         if (ret)
 259                 goto error;
 260
 261         ret = _lttng_kprobes_register(symbol_name, offset, addr,
 262                 &event_notifier->priv->parent.u.kprobe, lttng_kprobes_event_handler_pre);
 263         if (ret)
 264                 goto register_error;
 265
 266         return 0;
 267
 268 register_error:
 269         kfree(event_notifier->priv->parent.desc->event_name);
 270         kfree(event_notifier->priv->parent.desc);
 271 error:
 272         return ret;
 273 }
 274 EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier);
 275
 276 void lttng_kprobes_unregister_event(struct lttng_kernel_event_recorder *event_recorder)
 277 {
 278         unregister_kprobe(&event_recorder->priv->parent.u.kprobe.kp);
 279 }
 280 EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);
 281
 282 void lttng_kprobes_unregister_event_notifier(struct lttng_kernel_event_notifier *event_notifier)
 283 {
 284         unregister_kprobe(&event_notifier->priv->parent.u.kprobe.kp);
 285 }
 286 EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier);
 287
 288 void lttng_kprobes_destroy_event_private(struct lttng_kernel_event_recorder *event_recorder)
 289 {
 290         kfree(event_recorder->priv->parent.u.kprobe.symbol_name);
 291         kfree(event_recorder->priv->parent.desc->fields[0]);
 292         kfree(event_recorder->priv->parent.desc->fields);
 293         kfree(event_recorder->priv->parent.desc->event_name);
 294         kfree(event_recorder->priv->parent.desc);
 295 }
 296 EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);
 297
 298 void lttng_kprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier)
 299 {
 300         kfree(event_notifier->priv->parent.u.kprobe.symbol_name);
 301         kfree(event_notifier->priv->parent.desc->event_name);
 302         kfree(event_notifier->priv->parent.desc);
 303 }
 304 EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private);
 305
 306 MODULE_LICENSE("GPL and additional rights");
 307 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 308 MODULE_DESCRIPTION("LTTng kprobes probes");
 309 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 310         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 311         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 312         LTTNG_MODULES_EXTRAVERSION);