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