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