src/bin/lttng-sessiond/lttng-syscall.c

   1 /*
   2  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <stdbool.h>
  20
  21 #include <common/common.h>
  22 #include <common/kernel-ctl/kernel-ctl.h>
  23
  24 #include "lttng-sessiond.h"
  25 #include "kernel.h"
  26 #include "lttng-syscall.h"
  27 #include "utils.h"
  28
  29 /* Global syscall table. */
  30 struct syscall *syscall_table;
  31
  32 /* Number of entry in the syscall table. */
  33 static size_t syscall_table_nb_entry;
  34
  35 /*
  36  * Populate the system call table using the kernel tracer.
  37  *
  38  * Return 0 on success and the syscall table is allocated. On error, a negative
  39  * value is returned.
  40  */
  41 int syscall_init_table(void)
  42 {
  43         int ret, fd, err;
  44         size_t nbmem;
  45         FILE *fp;
  46         /* Syscall data from the kernel. */
  47         size_t index = 0;
  48         bool at_least_one_syscall = false;
  49         uint32_t bitness;
  50         char name[SYSCALL_NAME_LEN];
  51
  52         DBG3("Syscall init system call table");
  53
  54         fd = kernctl_syscall_list(kernel_tracer_fd);
  55         if (fd < 0) {
  56                 ret = fd;
  57                 PERROR("kernelctl syscall list");
  58                 goto error_ioctl;
  59         }
  60
  61         fp = fdopen(fd, "r");
  62         if (!fp) {
  63                 ret = -errno;
  64                 PERROR("syscall list fdopen");
  65                 goto error_fp;
  66         }
  67
  68         nbmem = SYSCALL_TABLE_INIT_SIZE;
  69         syscall_table = zmalloc(sizeof(struct syscall) * nbmem);
  70         if (!syscall_table) {
  71                 ret = -errno;
  72                 PERROR("syscall list zmalloc");
  73                 goto error;
  74         }
  75
  76         while (fscanf(fp,
  77                                 "syscall { index = %zu; \
  78                                 name = %" XSTR(SYSCALL_NAME_LEN) "[^;]; \
  79                                 bitness = %u; };\n",
  80                                 &index, name, &bitness) == 3) {
  81                 at_least_one_syscall = true;
  82                 if (index >= nbmem) {
  83                         struct syscall *new_list;
  84                         size_t new_nbmem;
  85
  86                         /* Double memory size. */
  87                         new_nbmem = max(index + 1, nbmem << 1);
  88                         if (new_nbmem > (SIZE_MAX / sizeof(*new_list))) {
  89                                 /* Overflow, stop everything, something went really wrong. */
  90                                 ERR("Syscall listing memory size overflow. Stopping");
  91                                 free(syscall_table);
  92                                 syscall_table = NULL;
  93                                 ret = -EINVAL;
  94                                 goto error;
  95                         }
  96
  97                         DBG("Reallocating syscall table from %zu to %zu entries", nbmem,
  98                                         new_nbmem);
  99                         new_list = realloc(syscall_table, new_nbmem * sizeof(*new_list));
 100                         if (!new_list) {
 101                                 ret = -errno;
 102                                 PERROR("syscall list realloc");
 103                                 goto error;
 104                         }
 105
 106                         /* Zero out the new memory. */
 107                         memset(new_list + nbmem, 0,
 108                                         (new_nbmem - nbmem) * sizeof(*new_list));
 109                         nbmem = new_nbmem;
 110                         syscall_table = new_list;
 111                 }
 112                 syscall_table[index].index = index;
 113                 syscall_table[index].bitness = bitness;
 114                 if (lttng_strncpy(syscall_table[index].name, name,
 115                                 sizeof(syscall_table[index].name))) {
 116                         ret = -EINVAL;
 117                         free(syscall_table);
 118                         syscall_table = NULL;
 119                         goto error;
 120                 }
 121                 /*
 122                 DBG("Syscall name '%s' at index %" PRIu32 " of bitness %u",
 123                                 syscall_table[index].name,
 124                                 syscall_table[index].index,
 125                                 syscall_table[index].bitness);
 126                 */
 127         }
 128
 129         /* Index starts at 0. */
 130         if (at_least_one_syscall) {
 131                 syscall_table_nb_entry = index + 1;
 132         }
 133
 134         ret = 0;
 135
 136 error:
 137         err = fclose(fp);
 138         if (err) {
 139                 PERROR("syscall list fclose");
 140         }
 141         return ret;
 142
 143 error_fp:
 144         err = close(fd);
 145         if (err) {
 146                 PERROR("syscall list close");
 147         }
 148
 149 error_ioctl:
 150         return ret;
 151 }
 152
 153 /*
 154  * Helper function for the list syscalls command that empty the temporary
 155  * syscall hashtable used to track duplicate between 32 and 64 bit arch.
 156  *
 157  * This empty the hash table and destroys it after. After this, the pointer is
 158  * unsuable. RCU read side lock MUST be acquired before calling this.
 159  */
 160 static void destroy_syscall_ht(struct lttng_ht *ht)
 161 {
 162         struct lttng_ht_iter iter;
 163         struct syscall *ksyscall;
 164
 165         DBG3("Destroying syscall hash table.");
 166
 167         if (!ht) {
 168                 return;
 169         }
 170
 171         cds_lfht_for_each_entry(ht->ht, &iter.iter, ksyscall, node.node) {
 172                 int ret;
 173
 174                 ret = lttng_ht_del(ht, &iter);
 175                 assert(!ret);
 176                 free(ksyscall);
 177         }
 178         ht_cleanup_push(ht);
 179 }
 180
 181 /*
 182  * Allocate the given hashtable pointer.
 183  *
 184  * Return 0 on success else a negative LTTNG error value.
 185  */
 186 static int init_syscall_ht(struct lttng_ht **ht)
 187 {
 188         int ret;
 189
 190         *ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 191         if (!*ht) {
 192                 ret = -LTTNG_ERR_NOMEM;
 193         } else {
 194                 ret = 0;
 195         }
 196
 197         return ret;
 198 }
 199
 200 /*
 201  * Lookup a syscall in the given hash table by name.
 202  *
 203  * Return syscall object if found or else NULL.
 204  */
 205 static struct syscall *lookup_syscall(struct lttng_ht *ht, const char *name)
 206 {
 207         struct lttng_ht_node_str *node;
 208         struct lttng_ht_iter iter;
 209         struct syscall *ksyscall = NULL;
 210
 211         assert(ht);
 212         assert(name);
 213
 214         lttng_ht_lookup(ht, (void *) name, &iter);
 215         node = lttng_ht_iter_get_node_str(&iter);
 216         if (node) {
 217                 ksyscall = caa_container_of(node, struct syscall, node);
 218         }
 219
 220         return ksyscall;
 221 }
 222
 223 /*
 224  * Using the given syscall object in the events array with the bitness of the
 225  * syscall at index in the syscall table.
 226  */
 227 static void update_event_syscall_bitness(struct lttng_event *events,
 228                 unsigned int index, unsigned int syscall_index)
 229 {
 230         assert(events);
 231
 232         if (syscall_table[index].bitness == 32) {
 233                 events[syscall_index].flags |= LTTNG_EVENT_FLAG_SYSCALL_32;
 234         } else {
 235                 events[syscall_index].flags |= LTTNG_EVENT_FLAG_SYSCALL_64;
 236         }
 237 }
 238
 239 /*
 240  * Allocate and initialize syscall object and add it to the given hashtable.
 241  *
 242  * Return 0 on success else -LTTNG_ERR_NOMEM.
 243  */
 244 static int add_syscall_to_ht(struct lttng_ht *ht, unsigned int index,
 245                 unsigned int syscall_index)
 246 {
 247         int ret;
 248         struct syscall *ksyscall;
 249
 250         assert(ht);
 251
 252         ksyscall = zmalloc(sizeof(*ksyscall));
 253         if (!ksyscall) {
 254                 ret = -LTTNG_ERR_NOMEM;
 255                 goto error;
 256         }
 257
 258         strncpy(ksyscall->name, syscall_table[index].name,
 259                         sizeof(ksyscall->name));
 260         ksyscall->bitness = syscall_table[index].bitness;
 261         ksyscall->index = syscall_index;
 262         lttng_ht_node_init_str(&ksyscall->node, ksyscall->name);
 263         lttng_ht_add_unique_str(ht, &ksyscall->node);
 264         ret = 0;
 265
 266 error:
 267         return ret;
 268 }
 269
 270 /*
 271  * List syscalls present in the kernel syscall global array, allocate and
 272  * populate the events structure with them. Skip the empty syscall name.
 273  *
 274  * Return the number of entries in the array else a negative value.
 275  */
 276 ssize_t syscall_table_list(struct lttng_event **_events)
 277 {
 278         int i, index = 0;
 279         ssize_t ret;
 280         struct lttng_event *events;
 281         /* Hash table used to filter duplicate out. */
 282         struct lttng_ht *syscalls_ht = NULL;
 283
 284         assert(_events);
 285
 286         DBG("Syscall table listing.");
 287
 288         rcu_read_lock();
 289
 290         /*
 291          * Allocate at least the number of total syscall we have even if some of
 292          * them might not be valid. The count below will make sure to return the
 293          * right size of the events array.
 294          */
 295         events = zmalloc(syscall_table_nb_entry * sizeof(*events));
 296         if (!events) {
 297                 PERROR("syscall table list zmalloc");
 298                 ret = -LTTNG_ERR_NOMEM;
 299                 goto error;
 300         }
 301
 302         ret = init_syscall_ht(&syscalls_ht);
 303         if (ret < 0) {
 304                 goto error;
 305         }
 306
 307         for (i = 0; i < syscall_table_nb_entry; i++) {
 308                 struct syscall *ksyscall;
 309
 310                 /* Skip empty syscalls. */
 311                 if (*syscall_table[i].name == '\0') {
 312                         continue;
 313                 }
 314
 315                 ksyscall = lookup_syscall(syscalls_ht, syscall_table[i].name);
 316                 if (ksyscall) {
 317                         update_event_syscall_bitness(events, i, ksyscall->index);
 318                         continue;
 319                 }
 320
 321                 ret = add_syscall_to_ht(syscalls_ht, i, index);
 322                 if (ret < 0) {
 323                         goto error;
 324                 }
 325
 326                 /* Copy the event information in the event's array. */
 327                 strncpy(events[index].name, syscall_table[i].name,
 328                                 sizeof(events[index].name));
 329                 update_event_syscall_bitness(events, i, index);
 330                 events[index].type = LTTNG_EVENT_SYSCALL;
 331                 /* This makes the command line not print the enabled/disabled field. */
 332                 events[index].enabled = -1;
 333                 index++;
 334         }
 335
 336         destroy_syscall_ht(syscalls_ht);
 337         *_events = events;
 338         rcu_read_unlock();
 339         return index;
 340
 341 error:
 342         destroy_syscall_ht(syscalls_ht);
 343         free(events);
 344         rcu_read_unlock();
 345         return ret;
 346 }