src/bin/lttng-sessiond/modprobe.c

   1 /*
   2  * Copyright (C) 2011 David Goulet <dgoulet@efficios.com>
   3  * Copyright (C) 2014 Jan Glauber <jan.glauber@gmail.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 /**
  10  * @file modprobe.c
  11  *
  12  * @brief modprobe related functions.
  13  *
  14  */
  15
  16 #define _LGPL_SOURCE
  17 #include <assert.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <sys/wait.h>
  21
  22 #include <common/common.h>
  23 #include <common/utils.h>
  24
  25 #include "modprobe.h"
  26 #include "kern-modules.h"
  27 #include "lttng-sessiond.h"
  28
  29 #define LTTNG_MOD_REQUIRED      1
  30 #define LTTNG_MOD_OPTIONAL      0
  31
  32 /* LTTng kernel tracer mandatory core modules list */
  33 /* TODO: the new trigger client might not be present in previous lttng-modules
  34  * should it be optional?
  35  * Can we reuse this to also know of the trigger feature is supported?
  36  */
  37 struct kern_modules_param kern_modules_control_core[] = {
  38         { (char *) "lttng-ring-buffer-client-discard" },
  39         { (char *) "lttng-ring-buffer-client-overwrite" },
  40         { (char *) "lttng-ring-buffer-metadata-client" },
  41         { (char *) "lttng-ring-buffer-client-mmap-discard" },
  42         { (char *) "lttng-ring-buffer-client-mmap-overwrite" },
  43         { (char *) "lttng-ring-buffer-metadata-mmap-client" },
  44         { (char *) "lttng-ring-buffer-trigger-client" },
  45         { (char *) "lttng-counter-client-percpu-64-modular" },
  46         { (char *) "lttng-counter-client-percpu-32-modular" },
  47 };
  48
  49 /* LTTng kernel tracer probe modules list */
  50 struct kern_modules_param kern_modules_probes_default[] = {
  51         { (char *) "lttng-probe-asoc" },
  52         { (char *) "lttng-probe-block" },
  53         { (char *) "lttng-probe-btrfs" },
  54         { (char *) "lttng-probe-compaction" },
  55         { (char *) "lttng-probe-ext3" },
  56         { (char *) "lttng-probe-ext4" },
  57         { (char *) "lttng-probe-gpio" },
  58         { (char *) "lttng-probe-i2c" },
  59         { (char *) "lttng-probe-irq" },
  60         { (char *) "lttng-probe-jbd" },
  61         { (char *) "lttng-probe-jbd2" },
  62         { (char *) "lttng-probe-kmem" },
  63         { (char *) "lttng-probe-kvm" },
  64         { (char *) "lttng-probe-kvm-x86" },
  65         { (char *) "lttng-probe-kvm-x86-mmu" },
  66         { (char *) "lttng-probe-lock" },
  67         { (char *) "lttng-probe-module" },
  68         { (char *) "lttng-probe-napi" },
  69         { (char *) "lttng-probe-net" },
  70         { (char *) "lttng-probe-power" },
  71         { (char *) "lttng-probe-preemptirq" },
  72         { (char *) "lttng-probe-printk" },
  73         { (char *) "lttng-probe-random" },
  74         { (char *) "lttng-probe-rcu" },
  75         { (char *) "lttng-probe-regmap" },
  76         { (char *) "lttng-probe-regulator" },
  77         { (char *) "lttng-probe-rpm" },
  78         { (char *) "lttng-probe-sched" },
  79         { (char *) "lttng-probe-scsi" },
  80         { (char *) "lttng-probe-signal" },
  81         { (char *) "lttng-probe-skb" },
  82         { (char *) "lttng-probe-sock" },
  83         { (char *) "lttng-probe-statedump" },
  84         { (char *) "lttng-probe-sunrpc" },
  85         { (char *) "lttng-probe-timer" },
  86         { (char *) "lttng-probe-udp" },
  87         { (char *) "lttng-probe-vmscan" },
  88         { (char *) "lttng-probe-v4l2" },
  89         { (char *) "lttng-probe-workqueue" },
  90         { (char *) "lttng-probe-writeback" },
  91         { (char *) "lttng-probe-x86-irq-vectors" },
  92         { (char *) "lttng-probe-x86-exceptions" },
  93 };
  94
  95 /* dynamic probe modules list */
  96 static struct kern_modules_param *probes;
  97 static int nr_probes;
  98 static int probes_capacity;
  99
 100 #if HAVE_KMOD
 101 #include <libkmod.h>
 102
 103 /**
 104  * @brief Logging function for libkmod integration.
 105  */
 106 static void log_kmod(void *data, int priority, const char *file, int line,
 107                 const char *fn, const char *format, va_list args)
 108 {
 109         char *str;
 110
 111         if (vasprintf(&str, format, args) < 0) {
 112                 return;
 113         }
 114
 115         DBG("libkmod: %s", str);
 116         free(str);
 117 }
 118
 119 /**
 120  * @brief Setup the libkmod context.
 121  *
 122  * Create the context, add a custom logging function and preload the
 123  * ressources for faster operation.
 124  *
 125  * @returns     \c 0 on success
 126  *              \c < 0 on error
 127  */
 128 static int setup_kmod_ctx(struct kmod_ctx **ctx)
 129 {
 130         int ret = 0;
 131
 132         *ctx = kmod_new(NULL, NULL);
 133         if (!ctx) {
 134                 PERROR("Unable to create kmod library context");
 135                 ret = -ENOMEM;
 136                 goto error;
 137         }
 138
 139         kmod_set_log_fn(*ctx, log_kmod, NULL);
 140         ret = kmod_load_resources(*ctx);
 141         if (ret < 0) {
 142                 ERR("Failed to load kmod library resources");
 143                 goto error;
 144         }
 145
 146 error:
 147         return ret;
 148 }
 149
 150 /**
 151  * @brief Loads the kernel modules in \p modules
 152  *
 153  * @param modules       List of modules to load
 154  * @param entries       Number of modules in the list
 155  * @param required      Are the modules required or optionnal
 156  *
 157  * If the modules are required, we will return with error after the
 158  * first failed module load, otherwise we continue loading.
 159  *
 160  * @returns             \c 0 on success
 161  *                      \c < 0 on error
 162  */
 163 static int modprobe_lttng(struct kern_modules_param *modules,
 164                 int entries, int required)
 165 {
 166         int ret = 0, i;
 167         struct kmod_ctx *ctx;
 168
 169         ret = setup_kmod_ctx(&ctx);
 170         if (ret < 0) {
 171                 goto error;
 172         }
 173
 174         for (i = 0; i < entries; i++) {
 175                 struct kmod_module *mod = NULL;
 176
 177                 ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
 178                 if (ret < 0) {
 179                         PERROR("Failed to create kmod module for %s", modules[i].name);
 180                         goto error;
 181                 }
 182
 183                 ret = kmod_module_probe_insert_module(mod, 0,
 184                                 NULL, NULL, NULL, NULL);
 185                 if (ret == -EEXIST) {
 186                         DBG("Module %s is already loaded", modules[i].name);
 187                         ret = 0;
 188                 } else if (ret < 0) {
 189                         if (required) {
 190                                 ERR("Unable to load required module %s",
 191                                                 modules[i].name);
 192                                 goto error;
 193                         } else {
 194                                 DBG("Unable to load optional module %s; continuing",
 195                                                 modules[i].name);
 196                                 ret = 0;
 197                         }
 198                 } else {
 199                         DBG("Modprobe successfully %s", modules[i].name);
 200                         modules[i].loaded = true;
 201                 }
 202
 203                 kmod_module_unref(mod);
 204         }
 205
 206 error:
 207         if (ctx) {
 208                 kmod_unref(ctx);
 209         }
 210         return ret;
 211 }
 212
 213 /**
 214  * @brief Recursively unload modules.
 215  *
 216  * This function implements the same modules unloading behavior as
 217  * 'modprobe -r' or rmmod, it will recursevily go trought the \p module
 218  * dependencies and unload modules with a refcount of 0.
 219  *
 220  * @param mod           The module to unload
 221  *
 222  * @returns             \c 0 on success
 223  *                      \c < 0 on error
 224  */
 225 static int rmmod_recurse(struct kmod_module *mod) {
 226         int ret = 0;
 227         struct kmod_list *deps, *itr;
 228
 229         if (kmod_module_get_initstate(mod) == KMOD_MODULE_BUILTIN) {
 230                 DBG("Module %s is builtin", kmod_module_get_name(mod));
 231                 return ret;
 232         }
 233
 234         ret = kmod_module_remove_module(mod, 0);
 235
 236         deps = kmod_module_get_dependencies(mod);
 237         if (deps != NULL) {
 238                 kmod_list_foreach(itr, deps) {
 239                         struct kmod_module *dep = kmod_module_get_module(itr);
 240                         if (kmod_module_get_refcnt(dep) == 0) {
 241                                 DBG("Recursive remove module %s",
 242                                                 kmod_module_get_name(dep));
 243                                 rmmod_recurse(dep);
 244                         }
 245                         kmod_module_unref(dep);
 246                 }
 247                 kmod_module_unref_list(deps);
 248         }
 249
 250         return ret;
 251 }
 252
 253 /**
 254  * @brief Unloads the kernel modules in \p modules
 255  *
 256  * @param modules       List of modules to unload
 257  * @param entries       Number of modules in the list
 258  * @param required      Are the modules required or optionnal
 259  *
 260  */
 261 static void modprobe_remove_lttng(const struct kern_modules_param *modules,
 262                 int entries, int required)
 263 {
 264         int ret = 0, i;
 265         struct kmod_ctx *ctx;
 266
 267         ret = setup_kmod_ctx(&ctx);
 268         if (ret < 0) {
 269                 goto error;
 270         }
 271
 272         for (i = entries - 1; i >= 0; i--) {
 273                 struct kmod_module *mod = NULL;
 274
 275                 if (!modules[i].loaded) {
 276                         continue;
 277                 }
 278
 279                 ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
 280                 if (ret < 0) {
 281                         PERROR("Failed to create kmod module for %s", modules[i].name);
 282                         goto error;
 283                 }
 284
 285                 ret = rmmod_recurse(mod);
 286                 if (ret == -EEXIST) {
 287                         DBG("Module %s is not in kernel.", modules[i].name);
 288                 } else if (required && ret < 0) {
 289                         ERR("Unable to remove module %s", modules[i].name);
 290                 } else {
 291                         DBG("Modprobe removal successful %s",
 292                                 modules[i].name);
 293                 }
 294
 295                 kmod_module_unref(mod);
 296         }
 297
 298 error:
 299         if (ctx) {
 300                 kmod_unref(ctx);
 301         }
 302 }
 303
 304 #else /* HAVE_KMOD */
 305
 306 static int modprobe_lttng(struct kern_modules_param *modules,
 307                 int entries, int required)
 308 {
 309         int ret = 0, i;
 310         char modprobe[256];
 311
 312         for (i = 0; i < entries; i++) {
 313                 ret = snprintf(modprobe, sizeof(modprobe),
 314                                 "/sbin/modprobe %s%s",
 315                                 required ? "" : "-q ",
 316                                 modules[i].name);
 317                 if (ret < 0) {
 318                         PERROR("snprintf modprobe");
 319                         goto error;
 320                 }
 321                 modprobe[sizeof(modprobe) - 1] = '\0';
 322                 ret = system(modprobe);
 323                 if (ret == -1) {
 324                         if (required) {
 325                                 ERR("Unable to launch modprobe for required module %s",
 326                                                 modules[i].name);
 327                                 goto error;
 328                         } else {
 329                                 DBG("Unable to launch modprobe for optional module %s; continuing",
 330                                                 modules[i].name);
 331                                 ret = 0;
 332                         }
 333                 } else if (WEXITSTATUS(ret) != 0) {
 334                         if (required) {
 335                                 ERR("Unable to load required module %s",
 336                                                 modules[i].name);
 337                                 goto error;
 338                         } else {
 339                                 DBG("Unable to load optional module %s; continuing",
 340                                                 modules[i].name);
 341                                 ret = 0;
 342                         }
 343                 } else {
 344                         DBG("Modprobe successfully %s", modules[i].name);
 345                         modules[i].loaded = true;
 346                 }
 347         }
 348
 349 error:
 350         return ret;
 351 }
 352
 353 static void modprobe_remove_lttng(const struct kern_modules_param *modules,
 354                 int entries, int required)
 355 {
 356         int ret = 0, i;
 357         char modprobe[256];
 358
 359         for (i = entries - 1; i >= 0; i--) {
 360                 if (!modules[i].loaded) {
 361                         continue;
 362                 }
 363                 ret = snprintf(modprobe, sizeof(modprobe),
 364                                 "/sbin/modprobe -r -q %s",
 365                                 modules[i].name);
 366                 if (ret < 0) {
 367                         PERROR("snprintf modprobe -r");
 368                         return;
 369                 }
 370                 modprobe[sizeof(modprobe) - 1] = '\0';
 371                 ret = system(modprobe);
 372                 if (ret == -1) {
 373                         ERR("Unable to launch modprobe -r for module %s",
 374                                         modules[i].name);
 375                 } else if (required && WEXITSTATUS(ret) != 0) {
 376                         ERR("Unable to remove module %s",
 377                                         modules[i].name);
 378                 } else {
 379                         DBG("Modprobe removal successful %s",
 380                                         modules[i].name);
 381                 }
 382         }
 383 }
 384
 385 #endif /* HAVE_KMOD */
 386
 387 /*
 388  * Remove control kernel module(s) in reverse load order.
 389  */
 390 void modprobe_remove_lttng_control(void)
 391 {
 392         modprobe_remove_lttng(kern_modules_control_core,
 393                               ARRAY_SIZE(kern_modules_control_core),
 394                               LTTNG_MOD_REQUIRED);
 395 }
 396
 397 static void free_probes(void)
 398 {
 399         int i;
 400
 401         if (!probes) {
 402                 return;
 403         }
 404         for (i = 0; i < nr_probes; ++i) {
 405                 free(probes[i].name);
 406         }
 407         free(probes);
 408         probes = NULL;
 409         nr_probes = 0;
 410 }
 411
 412 /*
 413  * Remove data kernel modules in reverse load order.
 414  */
 415 void modprobe_remove_lttng_data(void)
 416 {
 417         if (!probes) {
 418                 return;
 419         }
 420         modprobe_remove_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 421         free_probes();
 422 }
 423
 424 /*
 425  * Remove all kernel modules in reverse order.
 426  */
 427 void modprobe_remove_lttng_all(void)
 428 {
 429         modprobe_remove_lttng_data();
 430         modprobe_remove_lttng_control();
 431 }
 432
 433 /*
 434  * Load control kernel module(s).
 435  */
 436 int modprobe_lttng_control(void)
 437 {
 438         int ret;
 439
 440         ret = modprobe_lttng(kern_modules_control_core,
 441                              ARRAY_SIZE(kern_modules_control_core),
 442                              LTTNG_MOD_REQUIRED);
 443         return ret;
 444 }
 445
 446 /**
 447  * Grow global list of probes (double capacity or set it to 1 if
 448  * currently 0 and copy existing data).
 449  */
 450 static int grow_probes(void)
 451 {
 452         int i;
 453         struct kern_modules_param *tmp_probes;
 454
 455         /* Initialize capacity to 1 if 0. */
 456         if (probes_capacity == 0) {
 457                 probes = zmalloc(sizeof(*probes));
 458                 if (!probes) {
 459                         PERROR("malloc probe list");
 460                         return -ENOMEM;
 461                 }
 462
 463                 probes_capacity = 1;
 464                 return 0;
 465         }
 466
 467         /* Double size. */
 468         probes_capacity *= 2;
 469
 470         tmp_probes = zmalloc(sizeof(*tmp_probes) * probes_capacity);
 471         if (!tmp_probes) {
 472                 PERROR("malloc probe list");
 473                 return -ENOMEM;
 474         }
 475
 476         for (i = 0; i < nr_probes; ++i) {
 477                 /* Move name pointer. */
 478                 tmp_probes[i].name = probes[i].name;
 479         }
 480
 481         /* Replace probes with larger copy. */
 482         free(probes);
 483         probes = tmp_probes;
 484
 485         return 0;
 486 }
 487
 488 /*
 489  * Appends a comma-separated list of probes to the global list
 490  * of probes.
 491  */
 492 static int append_list_to_probes(const char *list)
 493 {
 494         char *next;
 495         int ret;
 496         char *tmp_list, *cur_list;
 497
 498         assert(list);
 499
 500         cur_list = tmp_list = strdup(list);
 501         if (!tmp_list) {
 502                 PERROR("strdup temp list");
 503                 return -ENOMEM;
 504         }
 505
 506         for (;;) {
 507                 size_t name_len;
 508                 struct kern_modules_param *cur_mod;
 509
 510                 next = strtok(cur_list, ",");
 511                 if (!next) {
 512                         break;
 513                 }
 514                 cur_list = NULL;
 515
 516                 /* filter leading spaces */
 517                 while (*next == ' ') {
 518                         next++;
 519                 }
 520
 521                 if (probes_capacity <= nr_probes) {
 522                         ret = grow_probes();
 523                         if (ret) {
 524                                 goto error;
 525                         }
 526                 }
 527
 528                 /* Length 13 is "lttng-probe-" + \0 */
 529                 name_len = strlen(next) + 13;
 530
 531                 cur_mod = &probes[nr_probes];
 532                 cur_mod->name = zmalloc(name_len);
 533                 if (!cur_mod->name) {
 534                         PERROR("malloc probe list");
 535                         ret = -ENOMEM;
 536                         goto error;
 537                 }
 538
 539                 ret = snprintf(cur_mod->name, name_len, "lttng-probe-%s", next);
 540                 if (ret < 0) {
 541                         PERROR("snprintf modprobe name");
 542                         ret = -ENOMEM;
 543                         goto error;
 544                 }
 545
 546                 nr_probes++;
 547         }
 548
 549         free(tmp_list);
 550         return 0;
 551
 552 error:
 553         free(tmp_list);
 554         free_probes();
 555         return ret;
 556 }
 557
 558 /*
 559  * Load data kernel module(s).
 560  */
 561 int modprobe_lttng_data(void)
 562 {
 563         int ret, i;
 564         char *list;
 565
 566         /*
 567          * Base probes: either from command line option, environment
 568          * variable or default list.
 569          */
 570         list = config.kmod_probes_list.value;
 571         if (list) {
 572                 /* User-specified probes. */
 573                 ret = append_list_to_probes(list);
 574                 if (ret) {
 575                         return ret;
 576                 }
 577         } else {
 578                 /* Default probes. */
 579                 int def_len = ARRAY_SIZE(kern_modules_probes_default);
 580
 581                 probes = zmalloc(sizeof(*probes) * def_len);
 582                 if (!probes) {
 583                         PERROR("malloc probe list");
 584                         return -ENOMEM;
 585                 }
 586
 587                 nr_probes = probes_capacity = def_len;
 588
 589                 for (i = 0; i < def_len; ++i) {
 590                         char* name = strdup(kern_modules_probes_default[i].name);
 591
 592                         if (!name) {
 593                                 PERROR("strdup probe item");
 594                                 ret = -ENOMEM;
 595                                 goto error;
 596                         }
 597
 598                         probes[i].name = name;
 599                 }
 600         }
 601
 602         /*
 603          * Extra modules? Append them to current probes list.
 604          */
 605         list = config.kmod_extra_probes_list.value;
 606         if (list) {
 607                 ret = append_list_to_probes(list);
 608                 if (ret) {
 609                         goto error;
 610                 }
 611         }
 612
 613         /*
 614          * Load probes modules now.
 615          */
 616         ret = modprobe_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 617         if (ret) {
 618                 goto error;
 619         }
 620         return ret;
 621
 622 error:
 623         free_probes();
 624         return ret;
 625 }