lttng-syscalls.c

   1 /*
   2  * lttng-syscalls.c
   3  *
   4  * Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng syscall probes.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/compat.h>
  14 #include <asm/ptrace.h>
  15 #include <asm/syscall.h>
  16
  17 #include "lttng-events.h"
  18
  19 #ifndef CONFIG_COMPAT
  20 static inline int is_compat_task(void)
  21 {
  22         return 0;
  23 }
  24 #endif
  25
  26 static
  27 void syscall_entry_probe(void *__data, struct pt_regs *regs, long id);
  28
  29 /*
  30  * Take care of NOARGS not supported by mainline.
  31  */
  32 #define DECLARE_EVENT_CLASS_NOARGS(name, tstruct, assign, print)
  33 #define DEFINE_EVENT_NOARGS(template, name)
  34 #define TRACE_EVENT_NOARGS(name, struct, assign, print)
  35
  36 /*
  37  * Create LTTng tracepoint probes.
  38  */
  39 #define LTTNG_PACKAGE_BUILD
  40 #define CREATE_TRACE_POINTS
  41 #define TP_MODULE_OVERRIDE
  42 #define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers
  43
  44 #define PARAMS(args...) args
  45
  46 /* Hijack probe callback for system calls */
  47 #undef TP_PROBE_CB
  48 #define TP_PROBE_CB(_template)          &syscall_entry_probe
  49 #define SC_TRACE_EVENT(_name, _proto, _args, _struct, _assign, _printk) \
  50         TRACE_EVENT(_name, PARAMS(_proto), PARAMS(_args),\
  51                 PARAMS(_struct), PARAMS(_assign), PARAMS(_printk))
  52 #define SC_DECLARE_EVENT_CLASS_NOARGS(_name, _struct, _assign, _printk) \
  53         DECLARE_EVENT_CLASS_NOARGS(_name, PARAMS(_struct), PARAMS(_assign),\
  54                 PARAMS(_printk))
  55 #define SC_DEFINE_EVENT_NOARGS(_template, _name)                        \
  56         DEFINE_EVENT_NOARGS(_template, _name)
  57 #undef TRACE_SYSTEM
  58 #define TRACE_SYSTEM syscalls_integers
  59 #include "instrumentation/syscalls/headers/syscalls_integers.h"
  60 #undef TRACE_SYSTEM
  61 #define TRACE_SYSTEM syscalls_pointers
  62 #include "instrumentation/syscalls/headers/syscalls_pointers.h"
  63 #undef TRACE_SYSTEM
  64 #undef SC_TRACE_EVENT
  65 #undef SC_DECLARE_EVENT_CLASS_NOARGS
  66 #undef SC_DEFINE_EVENT_NOARGS
  67
  68 #define TRACE_SYSTEM syscalls_unknown
  69 #include "instrumentation/syscalls/headers/syscalls_unknown.h"
  70 #undef TRACE_SYSTEM
  71
  72 /* For compat syscalls */
  73 #undef _TRACE_SYSCALLS_integers_H
  74 #undef _TRACE_SYSCALLS_pointers_H
  75
  76 /* Hijack probe callback for system calls */
  77 #undef TP_PROBE_CB
  78 #define TP_PROBE_CB(_template)          &syscall_entry_probe
  79 #define SC_TRACE_EVENT(_name, _proto, _args, _struct, _assign, _printk) \
  80         TRACE_EVENT(compat_##_name, PARAMS(_proto), PARAMS(_args),      \
  81                 PARAMS(_struct), PARAMS(_assign),                       \
  82                 PARAMS(_printk))
  83 #define SC_DECLARE_EVENT_CLASS_NOARGS(_name, _struct, _assign, _printk) \
  84         DECLARE_EVENT_CLASS_NOARGS(compat_##_name, PARAMS(_struct),     \
  85                 PARAMS(_assign), PARAMS(_printk))
  86 #define SC_DEFINE_EVENT_NOARGS(_template, _name)                        \
  87         DEFINE_EVENT_NOARGS(compat_##_template, compat_##_name)
  88 #define TRACE_SYSTEM compat_syscalls_integers
  89 #include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
  90 #undef TRACE_SYSTEM
  91 #define TRACE_SYSTEM compat_syscalls_pointers
  92 #include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
  93 #undef TRACE_SYSTEM
  94 #undef SC_TRACE_EVENT
  95 #undef SC_DECLARE_EVENT_CLASS_NOARGS
  96 #undef SC_DEFINE_EVENT_NOARGS
  97 #undef TP_PROBE_CB
  98
  99 #undef TP_MODULE_OVERRIDE
 100 #undef LTTNG_PACKAGE_BUILD
 101 #undef CREATE_TRACE_POINTS
 102
 103 struct trace_syscall_entry {
 104         void *func;
 105         const struct lttng_event_desc *desc;
 106         const struct lttng_event_field *fields;
 107         unsigned int nrargs;
 108 };
 109
 110 #define CREATE_SYSCALL_TABLE
 111
 112 #undef TRACE_SYSCALL_TABLE
 113 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)     \
 114         [ _nr ] = {                                             \
 115                 .func = __event_probe__##_template,             \
 116                 .nrargs = (_nrargs),                            \
 117                 .fields = __event_fields___##_template,         \
 118                 .desc = &__event_desc___##_name,                \
 119         },
 120
 121 static const struct trace_syscall_entry sc_table[] = {
 122 #include "instrumentation/syscalls/headers/syscalls_integers.h"
 123 #include "instrumentation/syscalls/headers/syscalls_pointers.h"
 124 };
 125
 126 #undef TRACE_SYSCALL_TABLE
 127 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)     \
 128         [ _nr ] = {                                             \
 129                 .func = __event_probe__##compat_##_template,    \
 130                 .nrargs = (_nrargs),                            \
 131                 .fields = __event_fields___##compat_##_template,\
 132                 .desc = &__event_desc___##compat_##_name,       \
 133         },
 134
 135 /* Create compatibility syscall table */
 136 const struct trace_syscall_entry compat_sc_table[] = {
 137 #include "instrumentation/syscalls/headers/compat_syscalls_integers.h"
 138 #include "instrumentation/syscalls/headers/compat_syscalls_pointers.h"
 139 };
 140
 141 #undef CREATE_SYSCALL_TABLE
 142
 143 static void syscall_entry_unknown(struct lttng_event *event,
 144         struct pt_regs *regs, unsigned int id)
 145 {
 146         unsigned long args[UNKNOWN_SYSCALL_NRARGS];
 147
 148         syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
 149         if (unlikely(is_compat_task()))
 150                 __event_probe__compat_sys_unknown(event, id, args);
 151         else
 152                 __event_probe__sys_unknown(event, id, args);
 153 }
 154
 155 void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
 156 {
 157         struct lttng_channel *chan = __data;
 158         struct lttng_event *event, *unknown_event;
 159         const struct trace_syscall_entry *table, *entry;
 160         size_t table_len;
 161
 162         if (unlikely(is_compat_task())) {
 163                 table = compat_sc_table;
 164                 table_len = ARRAY_SIZE(compat_sc_table);
 165                 unknown_event = chan->sc_compat_unknown;
 166         } else {
 167                 table = sc_table;
 168                 table_len = ARRAY_SIZE(sc_table);
 169                 unknown_event = chan->sc_unknown;
 170         }
 171         if (unlikely(id >= table_len)) {
 172                 syscall_entry_unknown(unknown_event, regs, id);
 173                 return;
 174         }
 175         if (unlikely(is_compat_task()))
 176                 event = chan->compat_sc_table[id];
 177         else
 178                 event = chan->sc_table[id];
 179         if (unlikely(!event)) {
 180                 syscall_entry_unknown(unknown_event, regs, id);
 181                 return;
 182         }
 183         entry = &table[id];
 184         WARN_ON_ONCE(!entry);
 185
 186         switch (entry->nrargs) {
 187         case 0:
 188         {
 189                 void (*fptr)(void *__data) = entry->func;
 190
 191                 fptr(event);
 192                 break;
 193         }
 194         case 1:
 195         {
 196                 void (*fptr)(void *__data, unsigned long arg0) = entry->func;
 197                 unsigned long args[1];
 198
 199                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 200                 fptr(event, args[0]);
 201                 break;
 202         }
 203         case 2:
 204         {
 205                 void (*fptr)(void *__data,
 206                         unsigned long arg0,
 207                         unsigned long arg1) = entry->func;
 208                 unsigned long args[2];
 209
 210                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 211                 fptr(event, args[0], args[1]);
 212                 break;
 213         }
 214         case 3:
 215         {
 216                 void (*fptr)(void *__data,
 217                         unsigned long arg0,
 218                         unsigned long arg1,
 219                         unsigned long arg2) = entry->func;
 220                 unsigned long args[3];
 221
 222                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 223                 fptr(event, args[0], args[1], args[2]);
 224                 break;
 225         }
 226         case 4:
 227         {
 228                 void (*fptr)(void *__data,
 229                         unsigned long arg0,
 230                         unsigned long arg1,
 231                         unsigned long arg2,
 232                         unsigned long arg3) = entry->func;
 233                 unsigned long args[4];
 234
 235                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 236                 fptr(event, args[0], args[1], args[2], args[3]);
 237                 break;
 238         }
 239         case 5:
 240         {
 241                 void (*fptr)(void *__data,
 242                         unsigned long arg0,
 243                         unsigned long arg1,
 244                         unsigned long arg2,
 245                         unsigned long arg3,
 246                         unsigned long arg4) = entry->func;
 247                 unsigned long args[5];
 248
 249                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 250                 fptr(event, args[0], args[1], args[2], args[3], args[4]);
 251                 break;
 252         }
 253         case 6:
 254         {
 255                 void (*fptr)(void *__data,
 256                         unsigned long arg0,
 257                         unsigned long arg1,
 258                         unsigned long arg2,
 259                         unsigned long arg3,
 260                         unsigned long arg4,
 261                         unsigned long arg5) = entry->func;
 262                 unsigned long args[6];
 263
 264                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 265                 fptr(event, args[0], args[1], args[2],
 266                         args[3], args[4], args[5]);
 267                 break;
 268         }
 269         default:
 270                 break;
 271         }
 272 }
 273
 274 /* noinline to diminish caller stack size */
 275 static
 276 int fill_table(const struct trace_syscall_entry *table, size_t table_len,
 277         struct lttng_event **chan_table, struct lttng_channel *chan, void *filter)
 278 {
 279         const struct lttng_event_desc *desc;
 280         unsigned int i;
 281
 282         /* Allocate events for each syscall, insert into table */
 283         for (i = 0; i < table_len; i++) {
 284                 struct lttng_kernel_event ev;
 285                 desc = table[i].desc;
 286
 287                 if (!desc) {
 288                         /* Unknown syscall */
 289                         continue;
 290                 }
 291                 /*
 292                  * Skip those already populated by previous failed
 293                  * register for this channel.
 294                  */
 295                 if (chan_table[i])
 296                         continue;
 297                 memset(&ev, 0, sizeof(ev));
 298                 strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
 299                 ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 300                 ev.instrumentation = LTTNG_KERNEL_NOOP;
 301                 chan_table[i] = lttng_event_create(chan, &ev, filter,
 302                                                 desc);
 303                 if (!chan_table[i]) {
 304                         /*
 305                          * If something goes wrong in event registration
 306                          * after the first one, we have no choice but to
 307                          * leave the previous events in there, until
 308                          * deleted by session teardown.
 309                          */
 310                         return -EINVAL;
 311                 }
 312         }
 313         return 0;
 314 }
 315
 316 int lttng_syscalls_register(struct lttng_channel *chan, void *filter)
 317 {
 318         struct lttng_kernel_event ev;
 319         int ret;
 320
 321         wrapper_vmalloc_sync_all();
 322
 323         if (!chan->sc_table) {
 324                 /* create syscall table mapping syscall to events */
 325                 chan->sc_table = kzalloc(sizeof(struct lttng_event *)
 326                                         * ARRAY_SIZE(sc_table), GFP_KERNEL);
 327                 if (!chan->sc_table)
 328                         return -ENOMEM;
 329         }
 330
 331 #ifdef CONFIG_COMPAT
 332         if (!chan->compat_sc_table) {
 333                 /* create syscall table mapping compat syscall to events */
 334                 chan->compat_sc_table = kzalloc(sizeof(struct lttng_event *)
 335                                         * ARRAY_SIZE(compat_sc_table), GFP_KERNEL);
 336                 if (!chan->compat_sc_table)
 337                         return -ENOMEM;
 338         }
 339 #endif
 340         if (!chan->sc_unknown) {
 341                 const struct lttng_event_desc *desc =
 342                         &__event_desc___sys_unknown;
 343
 344                 memset(&ev, 0, sizeof(ev));
 345                 strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
 346                 ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 347                 ev.instrumentation = LTTNG_KERNEL_NOOP;
 348                 chan->sc_unknown = lttng_event_create(chan, &ev, filter,
 349                                                     desc);
 350                 if (!chan->sc_unknown) {
 351                         return -EINVAL;
 352                 }
 353         }
 354
 355         if (!chan->sc_compat_unknown) {
 356                 const struct lttng_event_desc *desc =
 357                         &__event_desc___compat_sys_unknown;
 358
 359                 memset(&ev, 0, sizeof(ev));
 360                 strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
 361                 ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 362                 ev.instrumentation = LTTNG_KERNEL_NOOP;
 363                 chan->sc_compat_unknown = lttng_event_create(chan, &ev, filter,
 364                                                            desc);
 365                 if (!chan->sc_compat_unknown) {
 366                         return -EINVAL;
 367                 }
 368         }
 369
 370         if (!chan->sc_exit) {
 371                 const struct lttng_event_desc *desc =
 372                         &__event_desc___exit_syscall;
 373
 374                 memset(&ev, 0, sizeof(ev));
 375                 strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
 376                 ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 377                 ev.instrumentation = LTTNG_KERNEL_NOOP;
 378                 chan->sc_exit = lttng_event_create(chan, &ev, filter,
 379                                                  desc);
 380                 if (!chan->sc_exit) {
 381                         return -EINVAL;
 382                 }
 383         }
 384
 385         ret = fill_table(sc_table, ARRAY_SIZE(sc_table),
 386                         chan->sc_table, chan, filter);
 387         if (ret)
 388                 return ret;
 389 #ifdef CONFIG_COMPAT
 390         ret = fill_table(compat_sc_table, ARRAY_SIZE(compat_sc_table),
 391                         chan->compat_sc_table, chan, filter);
 392         if (ret)
 393                 return ret;
 394 #endif
 395         ret = tracepoint_probe_register("sys_enter",
 396                         (void *) syscall_entry_probe, chan);
 397         if (ret)
 398                 return ret;
 399         /*
 400          * We change the name of sys_exit tracepoint due to namespace
 401          * conflict with sys_exit syscall entry.
 402          */
 403         ret = tracepoint_probe_register("sys_exit",
 404                         (void *) __event_probe__exit_syscall,
 405                         chan->sc_exit);
 406         if (ret) {
 407                 WARN_ON_ONCE(tracepoint_probe_unregister("sys_enter",
 408                         (void *) syscall_entry_probe, chan));
 409         }
 410         return ret;
 411 }
 412
 413 /*
 414  * Only called at session destruction.
 415  */
 416 int lttng_syscalls_unregister(struct lttng_channel *chan)
 417 {
 418         int ret;
 419
 420         if (!chan->sc_table)
 421                 return 0;
 422         ret = tracepoint_probe_unregister("sys_exit",
 423                         (void *) __event_probe__exit_syscall,
 424                         chan->sc_exit);
 425         if (ret)
 426                 return ret;
 427         ret = tracepoint_probe_unregister("sys_enter",
 428                         (void *) syscall_entry_probe, chan);
 429         if (ret)
 430                 return ret;
 431         /* lttng_event destroy will be performed by lttng_session_destroy() */
 432         kfree(chan->sc_table);
 433 #ifdef CONFIG_COMPAT
 434         kfree(chan->compat_sc_table);
 435 #endif
 436         return 0;
 437 }