lttng-syscalls.c

   1 /*
   2  * lttng-syscalls.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng sched probes.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <asm/ptrace.h>
  14 #include <asm/syscall.h>
  15
  16 #include "ltt-events.h"
  17
  18 static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id);
  19
  20 /*
  21  * Take care of NOARGS not supported by mainline.
  22  */
  23 #define DECLARE_EVENT_CLASS_NOARGS(name, tstruct, assign, print)
  24 #define DEFINE_EVENT_NOARGS(template, name)
  25 #define TRACE_EVENT_NOARGS(name, struct, assign, print)
  26
  27 /*
  28  * Create LTTng tracepoint probes.
  29  */
  30 #define LTTNG_PACKAGE_BUILD
  31 #define CREATE_TRACE_POINTS
  32
  33 /* Hijack probe callback for system calls */
  34 #define TP_PROBE_CB(_template)          &syscall_entry_probe
  35 #define TP_MODULE_OVERRIDE
  36
  37 #define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers
  38 #include "instrumentation/syscalls/headers/syscalls_integers.h"
  39 #include "instrumentation/syscalls/headers/syscalls_pointers.h"
  40 #include "instrumentation/syscalls/headers/syscalls_unknown.h"
  41
  42 #undef TP_MODULE_OVERRIDE
  43 #undef TP_PROBE_CB
  44 #undef LTTNG_PACKAGE_BUILD
  45 #undef CREATE_TRACE_POINTS
  46
  47 struct trace_syscall_entry {
  48         void *func;
  49         const struct lttng_event_desc *desc;
  50         const struct lttng_event_field *fields;
  51         unsigned int nrargs;
  52 };
  53
  54 #define CREATE_SYSCALL_TABLE
  55
  56 #undef TRACE_SYSCALL_TABLE
  57 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)     \
  58         [ _nr ] = {                                             \
  59                 .func = __event_probe__##_template,             \
  60                 .nrargs = (_nrargs),                            \
  61                 .fields = __event_fields___##_template,         \
  62                 .desc = &__event_desc___##_name,                \
  63         },
  64
  65 static struct trace_syscall_entry sc_table[] = {
  66 #include "instrumentation/syscalls/headers/syscalls_integers.h"
  67 #include "instrumentation/syscalls/headers/syscalls_pointers.h"
  68 };
  69
  70 #undef CREATE_SYSCALL_TABLE
  71
  72 static void syscall_entry_unknown(struct ltt_channel *chan,
  73         struct pt_regs *regs, unsigned int id)
  74 {
  75         unsigned long args[UNKNOWN_SYSCALL_NRARGS];
  76         struct ltt_event *event;
  77
  78         event = chan->sc_unknown;
  79         syscall_get_arguments(current, regs, 0, UNKNOWN_SYSCALL_NRARGS, args);
  80         __event_probe__sys_unknown(event, id, args);
  81 }
  82
  83 static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
  84 {
  85         struct trace_syscall_entry *entry;
  86         struct ltt_channel *chan = __data;
  87         struct ltt_event *event;
  88
  89         if (unlikely(id >= ARRAY_SIZE(sc_table))) {
  90                 syscall_entry_unknown(chan, regs, id);
  91                 return;
  92         }
  93         event = chan->sc_table[id];
  94         if (unlikely(!event)) {
  95                 syscall_entry_unknown(chan, regs, id);
  96                 return;
  97         }
  98         entry = &sc_table[id];
  99         WARN_ON_ONCE(!entry);
 100
 101         switch (entry->nrargs) {
 102         case 0:
 103         {
 104                 void (*fptr)(void *__data) = entry->func;
 105
 106                 fptr(event);
 107                 break;
 108         }
 109         case 1:
 110         {
 111                 void (*fptr)(void *__data, unsigned long arg0) = entry->func;
 112                 unsigned long args[1];
 113
 114                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 115                 fptr(event, args[0]);
 116                 break;
 117         }
 118         case 2:
 119         {
 120                 void (*fptr)(void *__data,
 121                         unsigned long arg0,
 122                         unsigned long arg1) = entry->func;
 123                 unsigned long args[2];
 124
 125                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 126                 fptr(event, args[0], args[1]);
 127                 break;
 128         }
 129         case 3:
 130         {
 131                 void (*fptr)(void *__data,
 132                         unsigned long arg0,
 133                         unsigned long arg1,
 134                         unsigned long arg2) = entry->func;
 135                 unsigned long args[3];
 136
 137                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 138                 fptr(event, args[0], args[1], args[2]);
 139                 break;
 140         }
 141         case 4:
 142         {
 143                 void (*fptr)(void *__data,
 144                         unsigned long arg0,
 145                         unsigned long arg1,
 146                         unsigned long arg2,
 147                         unsigned long arg3) = entry->func;
 148                 unsigned long args[4];
 149
 150                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 151                 fptr(event, args[0], args[1], args[2], args[3]);
 152                 break;
 153         }
 154         case 5:
 155         {
 156                 void (*fptr)(void *__data,
 157                         unsigned long arg0,
 158                         unsigned long arg1,
 159                         unsigned long arg2,
 160                         unsigned long arg3,
 161                         unsigned long arg4) = entry->func;
 162                 unsigned long args[5];
 163
 164                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 165                 fptr(event, args[0], args[1], args[2], args[3], args[4]);
 166                 break;
 167         }
 168         case 6:
 169         {
 170                 void (*fptr)(void *__data,
 171                         unsigned long arg0,
 172                         unsigned long arg1,
 173                         unsigned long arg2,
 174                         unsigned long arg3,
 175                         unsigned long arg4,
 176                         unsigned long arg5) = entry->func;
 177                 unsigned long args[6];
 178
 179                 syscall_get_arguments(current, regs, 0, entry->nrargs, args);
 180                 fptr(event, args[0], args[1], args[2],
 181                         args[3], args[4], args[5]);
 182                 break;
 183         }
 184         default:
 185                 break;
 186         }
 187 }
 188
 189 int lttng_syscalls_register(struct ltt_channel *chan, void *filter)
 190 {
 191         unsigned int i;
 192         int ret;
 193
 194         wrapper_vmalloc_sync_all();
 195
 196         if (!chan->sc_table) {
 197                 /* create syscall table mapping syscall to events */
 198                 chan->sc_table = kzalloc(sizeof(struct ltt_event *)
 199                                         * ARRAY_SIZE(sc_table), GFP_KERNEL);
 200                 if (!chan->sc_table)
 201                         return -ENOMEM;
 202         }
 203
 204         if (!chan->sc_unknown) {
 205                 struct lttng_kernel_event ev;
 206
 207                 const struct lttng_event_desc *desc =
 208                         &__event_desc___sys_unknown;
 209                 memset(&ev, 0, sizeof(ev));
 210                 strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
 211                 ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 212                 ev.instrumentation = LTTNG_KERNEL_NOOP;
 213                 chan->sc_unknown = ltt_event_create(chan, &ev, filter,
 214                                                     desc);
 215                 if (!chan->sc_unknown) {
 216                         return -EINVAL;
 217                 }
 218         }
 219
 220         /* Allocate events for each syscall, insert into table */
 221         for (i = 0; i < ARRAY_SIZE(sc_table); i++) {
 222                 struct lttng_kernel_event ev;
 223                 const struct lttng_event_desc *desc = sc_table[i].desc;
 224
 225                 if (!desc) {
 226                         /* Unknown syscall */
 227                         continue;
 228                 }
 229                 /*
 230                  * Skip those already populated by previous failed
 231                  * register for this channel.
 232                  */
 233                 if (chan->sc_table[i])
 234                         continue;
 235                 memset(&ev, 0, sizeof(ev));
 236                 strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
 237                 ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 238                 ev.instrumentation = LTTNG_KERNEL_NOOP;
 239                 chan->sc_table[i] = ltt_event_create(chan, &ev, filter,
 240                                                      desc);
 241                 if (!chan->sc_table[i]) {
 242                         /*
 243                          * If something goes wrong in event registration
 244                          * after the first one, we have no choice but to
 245                          * leave the previous events in there, until
 246                          * deleted by session teardown.
 247                          */
 248                         return -EINVAL;
 249                 }
 250         }
 251         ret = tracepoint_probe_register("sys_enter",
 252                         (void *) syscall_entry_probe, chan);
 253         if (ret)
 254                 return ret;
 255         /*
 256          * We change the name of sys_exit tracepoint due to namespace
 257          * conflict with sys_exit syscall entry.
 258          */
 259         ret = tracepoint_probe_register("sys_exit",
 260                         (void *) __event_probe__exit_syscall, chan);
 261         if (ret) {
 262                 WARN_ON_ONCE(tracepoint_probe_unregister("sys_enter",
 263                         (void *) syscall_entry_probe, chan));
 264         }
 265         return ret;
 266 }
 267
 268 /*
 269  * Only called at session destruction.
 270  */
 271 int lttng_syscalls_unregister(struct ltt_channel *chan)
 272 {
 273         int ret;
 274
 275         if (!chan->sc_table)
 276                 return 0;
 277         ret = tracepoint_probe_unregister("sys_exit",
 278                         (void *) __event_probe__exit_syscall, chan);
 279         if (ret)
 280                 return ret;
 281         ret = tracepoint_probe_unregister("sys_enter",
 282                         (void *) syscall_entry_probe, chan);
 283         if (ret)
 284                 return ret;
 285         /* ltt_event destroy will be performed by ltt_session_destroy() */
 286         kfree(chan->sc_table);
 287         return 0;
 288 }