plugins/core.c

   1 /*
   2  * QEMU Plugin Core code
   3  *
   4  * This is the core code that deals with injecting instrumentation into the code
   5  *
   6  * Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
   7  * Copyright (C) 2019, Linaro
   8  *
   9  * License: GNU GPL, version 2 or later.
  10  *   See the COPYING file in the top-level directory.
  11  *
  12  * SPDX-License-Identifier: GPL-2.0-or-later
  13  */
  14 #include "qemu/osdep.h"
  15 #include "qemu/error-report.h"
  16 #include "qemu/config-file.h"
  17 #include "qapi/error.h"
  18 #include "qemu/lockable.h"
  19 #include "qemu/option.h"
  20 #include "qemu/rcu_queue.h"
  21 #include "qemu/xxhash.h"
  22 #include "qemu/rcu.h"
  23 #include "hw/core/cpu.h"
  24 #include "exec/cpu-common.h"
  25
  26 #include "exec/exec-all.h"
  27 #include "exec/helper-proto.h"
  28 #include "tcg/tcg.h"
  29 #include "tcg/tcg-op.h"
  30 #include "plugin.h"
  31 #include "qemu/compiler.h"
  32
  33 struct qemu_plugin_cb {
  34     struct qemu_plugin_ctx *ctx;
  35     union qemu_plugin_cb_sig f;
  36     void *udata;
  37     QLIST_ENTRY(qemu_plugin_cb) entry;
  38 };
  39
  40 struct qemu_plugin_state plugin;
  41
  42 struct qemu_plugin_ctx *plugin_id_to_ctx_locked(qemu_plugin_id_t id)
  43 {
  44     struct qemu_plugin_ctx *ctx;
  45     qemu_plugin_id_t *id_p;
  46
  47     id_p = g_hash_table_lookup(plugin.id_ht, &id);
  48     ctx = container_of(id_p, struct qemu_plugin_ctx, id);
  49     if (ctx == NULL) {
  50         error_report("plugin: invalid plugin id %" PRIu64, id);
  51         abort();
  52     }
  53     return ctx;
  54 }
  55
  56 static void plugin_cpu_update__async(CPUState *cpu, run_on_cpu_data data)
  57 {
  58     bitmap_copy(cpu->plugin_mask, &data.host_ulong, QEMU_PLUGIN_EV_MAX);
  59     tcg_flush_jmp_cache(cpu);
  60 }
  61
  62 static void plugin_cpu_update__locked(gpointer k, gpointer v, gpointer udata)
  63 {
  64     CPUState *cpu = container_of(k, CPUState, cpu_index);
  65     run_on_cpu_data mask = RUN_ON_CPU_HOST_ULONG(*plugin.mask);
  66
  67     if (cpu->created) {
  68         async_run_on_cpu(cpu, plugin_cpu_update__async, mask);
  69     } else {
  70         plugin_cpu_update__async(cpu, mask);
  71     }
  72 }
  73
  74 void plugin_unregister_cb__locked(struct qemu_plugin_ctx *ctx,
  75                                   enum qemu_plugin_event ev)
  76 {
  77     struct qemu_plugin_cb *cb = ctx->callbacks[ev];
  78
  79     if (cb == NULL) {
  80         return;
  81     }
  82     QLIST_REMOVE_RCU(cb, entry);
  83     g_free(cb);
  84     ctx->callbacks[ev] = NULL;
  85     if (QLIST_EMPTY_RCU(&plugin.cb_lists[ev])) {
  86         clear_bit(ev, plugin.mask);
  87         g_hash_table_foreach(plugin.cpu_ht, plugin_cpu_update__locked, NULL);
  88     }
  89 }
  90
  91 /*
  92  * Disable CFI checks.
  93  * The callback function has been loaded from an external library so we do not
  94  * have type information
  95  */
  96 QEMU_DISABLE_CFI
  97 static void plugin_vcpu_cb__simple(CPUState *cpu, enum qemu_plugin_event ev)
  98 {
  99     struct qemu_plugin_cb *cb, *next;
 100
 101     switch (ev) {
 102     case QEMU_PLUGIN_EV_VCPU_INIT:
 103     case QEMU_PLUGIN_EV_VCPU_EXIT:
 104     case QEMU_PLUGIN_EV_VCPU_IDLE:
 105     case QEMU_PLUGIN_EV_VCPU_RESUME:
 106         /* iterate safely; plugins might uninstall themselves at any time */
 107         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 108             qemu_plugin_vcpu_simple_cb_t func = cb->f.vcpu_simple;
 109
 110             func(cb->ctx->id, cpu->cpu_index);
 111         }
 112         break;
 113     default:
 114         g_assert_not_reached();
 115     }
 116 }
 117
 118 /*
 119  * Disable CFI checks.
 120  * The callback function has been loaded from an external library so we do not
 121  * have type information
 122  */
 123 QEMU_DISABLE_CFI
 124 static void plugin_cb__simple(enum qemu_plugin_event ev)
 125 {
 126     struct qemu_plugin_cb *cb, *next;
 127
 128     switch (ev) {
 129     case QEMU_PLUGIN_EV_FLUSH:
 130         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 131             qemu_plugin_simple_cb_t func = cb->f.simple;
 132
 133             func(cb->ctx->id);
 134         }
 135         break;
 136     default:
 137         g_assert_not_reached();
 138     }
 139 }
 140
 141 /*
 142  * Disable CFI checks.
 143  * The callback function has been loaded from an external library so we do not
 144  * have type information
 145  */
 146 QEMU_DISABLE_CFI
 147 static void plugin_cb__udata(enum qemu_plugin_event ev)
 148 {
 149     struct qemu_plugin_cb *cb, *next;
 150
 151     switch (ev) {
 152     case QEMU_PLUGIN_EV_ATEXIT:
 153         QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 154             qemu_plugin_udata_cb_t func = cb->f.udata;
 155
 156             func(cb->ctx->id, cb->udata);
 157         }
 158         break;
 159     default:
 160         g_assert_not_reached();
 161     }
 162 }
 163
 164 static void
 165 do_plugin_register_cb(qemu_plugin_id_t id, enum qemu_plugin_event ev,
 166                       void *func, void *udata)
 167 {
 168     struct qemu_plugin_ctx *ctx;
 169
 170     QEMU_LOCK_GUARD(&plugin.lock);
 171     ctx = plugin_id_to_ctx_locked(id);
 172     /* if the plugin is on its way out, ignore this request */
 173     if (unlikely(ctx->uninstalling)) {
 174         return;
 175     }
 176     if (func) {
 177         struct qemu_plugin_cb *cb = ctx->callbacks[ev];
 178
 179         if (cb) {
 180             cb->f.generic = func;
 181             cb->udata = udata;
 182         } else {
 183             cb = g_new(struct qemu_plugin_cb, 1);
 184             cb->ctx = ctx;
 185             cb->f.generic = func;
 186             cb->udata = udata;
 187             ctx->callbacks[ev] = cb;
 188             QLIST_INSERT_HEAD_RCU(&plugin.cb_lists[ev], cb, entry);
 189             if (!test_bit(ev, plugin.mask)) {
 190                 set_bit(ev, plugin.mask);
 191                 g_hash_table_foreach(plugin.cpu_ht, plugin_cpu_update__locked,
 192                                      NULL);
 193             }
 194         }
 195     } else {
 196         plugin_unregister_cb__locked(ctx, ev);
 197     }
 198 }
 199
 200 void plugin_register_cb(qemu_plugin_id_t id, enum qemu_plugin_event ev,
 201                         void *func)
 202 {
 203     do_plugin_register_cb(id, ev, func, NULL);
 204 }
 205
 206 void
 207 plugin_register_cb_udata(qemu_plugin_id_t id, enum qemu_plugin_event ev,
 208                          void *func, void *udata)
 209 {
 210     do_plugin_register_cb(id, ev, func, udata);
 211 }
 212
 213 void qemu_plugin_vcpu_init_hook(CPUState *cpu)
 214 {
 215     bool success;
 216
 217     qemu_rec_mutex_lock(&plugin.lock);
 218     plugin_cpu_update__locked(&cpu->cpu_index, NULL, NULL);
 219     success = g_hash_table_insert(plugin.cpu_ht, &cpu->cpu_index,
 220                                   &cpu->cpu_index);
 221     g_assert(success);
 222     qemu_rec_mutex_unlock(&plugin.lock);
 223
 224     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_INIT);
 225 }
 226
 227 void qemu_plugin_vcpu_exit_hook(CPUState *cpu)
 228 {
 229     bool success;
 230
 231     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_EXIT);
 232
 233     qemu_rec_mutex_lock(&plugin.lock);
 234     success = g_hash_table_remove(plugin.cpu_ht, &cpu->cpu_index);
 235     g_assert(success);
 236     qemu_rec_mutex_unlock(&plugin.lock);
 237 }
 238
 239 struct plugin_for_each_args {
 240     struct qemu_plugin_ctx *ctx;
 241     qemu_plugin_vcpu_simple_cb_t cb;
 242 };
 243
 244 static void plugin_vcpu_for_each(gpointer k, gpointer v, gpointer udata)
 245 {
 246     struct plugin_for_each_args *args = udata;
 247     int cpu_index = *(int *)k;
 248
 249     args->cb(args->ctx->id, cpu_index);
 250 }
 251
 252 void qemu_plugin_vcpu_for_each(qemu_plugin_id_t id,
 253                                qemu_plugin_vcpu_simple_cb_t cb)
 254 {
 255     struct plugin_for_each_args args;
 256
 257     if (cb == NULL) {
 258         return;
 259     }
 260     qemu_rec_mutex_lock(&plugin.lock);
 261     args.ctx = plugin_id_to_ctx_locked(id);
 262     args.cb = cb;
 263     g_hash_table_foreach(plugin.cpu_ht, plugin_vcpu_for_each, &args);
 264     qemu_rec_mutex_unlock(&plugin.lock);
 265 }
 266
 267 /* Allocate and return a callback record */
 268 static struct qemu_plugin_dyn_cb *plugin_get_dyn_cb(GArray **arr)
 269 {
 270     GArray *cbs = *arr;
 271
 272     if (!cbs) {
 273         cbs = g_array_sized_new(false, false,
 274                                 sizeof(struct qemu_plugin_dyn_cb), 1);
 275         *arr = cbs;
 276     }
 277
 278     g_array_set_size(cbs, cbs->len + 1);
 279     return &g_array_index(cbs, struct qemu_plugin_dyn_cb, cbs->len - 1);
 280 }
 281
 282 void plugin_register_inline_op(GArray **arr,
 283                                enum qemu_plugin_mem_rw rw,
 284                                enum qemu_plugin_op op, void *ptr,
 285                                uint64_t imm)
 286 {
 287     struct qemu_plugin_dyn_cb *dyn_cb;
 288
 289     dyn_cb = plugin_get_dyn_cb(arr);
 290     dyn_cb->userp = ptr;
 291     dyn_cb->type = PLUGIN_CB_INLINE;
 292     dyn_cb->rw = rw;
 293     dyn_cb->inline_insn.op = op;
 294     dyn_cb->inline_insn.imm = imm;
 295 }
 296
 297 void plugin_register_dyn_cb__udata(GArray **arr,
 298                                    qemu_plugin_vcpu_udata_cb_t cb,
 299                                    enum qemu_plugin_cb_flags flags,
 300                                    void *udata)
 301 {
 302     struct qemu_plugin_dyn_cb *dyn_cb = plugin_get_dyn_cb(arr);
 303
 304     dyn_cb->userp = udata;
 305     /* Note flags are discarded as unused. */
 306     dyn_cb->f.vcpu_udata = cb;
 307     dyn_cb->type = PLUGIN_CB_REGULAR;
 308 }
 309
 310 void plugin_register_vcpu_mem_cb(GArray **arr,
 311                                  void *cb,
 312                                  enum qemu_plugin_cb_flags flags,
 313                                  enum qemu_plugin_mem_rw rw,
 314                                  void *udata)
 315 {
 316     struct qemu_plugin_dyn_cb *dyn_cb;
 317
 318     dyn_cb = plugin_get_dyn_cb(arr);
 319     dyn_cb->userp = udata;
 320     /* Note flags are discarded as unused. */
 321     dyn_cb->type = PLUGIN_CB_REGULAR;
 322     dyn_cb->rw = rw;
 323     dyn_cb->f.generic = cb;
 324 }
 325
 326 /*
 327  * Disable CFI checks.
 328  * The callback function has been loaded from an external library so we do not
 329  * have type information
 330  */
 331 QEMU_DISABLE_CFI
 332 void qemu_plugin_tb_trans_cb(CPUState *cpu, struct qemu_plugin_tb *tb)
 333 {
 334     struct qemu_plugin_cb *cb, *next;
 335     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_TB_TRANS;
 336
 337     /* no plugin_mask check here; caller should have checked */
 338
 339     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 340         qemu_plugin_vcpu_tb_trans_cb_t func = cb->f.vcpu_tb_trans;
 341
 342         func(cb->ctx->id, tb);
 343     }
 344 }
 345
 346 /*
 347  * Disable CFI checks.
 348  * The callback function has been loaded from an external library so we do not
 349  * have type information
 350  */
 351 QEMU_DISABLE_CFI
 352 void
 353 qemu_plugin_vcpu_syscall(CPUState *cpu, int64_t num, uint64_t a1, uint64_t a2,
 354                          uint64_t a3, uint64_t a4, uint64_t a5,
 355                          uint64_t a6, uint64_t a7, uint64_t a8)
 356 {
 357     struct qemu_plugin_cb *cb, *next;
 358     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL;
 359
 360     if (!test_bit(ev, cpu->plugin_mask)) {
 361         return;
 362     }
 363
 364     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 365         qemu_plugin_vcpu_syscall_cb_t func = cb->f.vcpu_syscall;
 366
 367         func(cb->ctx->id, cpu->cpu_index, num, a1, a2, a3, a4, a5, a6, a7, a8);
 368     }
 369 }
 370
 371 /*
 372  * Disable CFI checks.
 373  * The callback function has been loaded from an external library so we do not
 374  * have type information
 375  */
 376 QEMU_DISABLE_CFI
 377 void qemu_plugin_vcpu_syscall_ret(CPUState *cpu, int64_t num, int64_t ret)
 378 {
 379     struct qemu_plugin_cb *cb, *next;
 380     enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL_RET;
 381
 382     if (!test_bit(ev, cpu->plugin_mask)) {
 383         return;
 384     }
 385
 386     QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 387         qemu_plugin_vcpu_syscall_ret_cb_t func = cb->f.vcpu_syscall_ret;
 388
 389         func(cb->ctx->id, cpu->cpu_index, num, ret);
 390     }
 391 }
 392
 393 void qemu_plugin_vcpu_idle_cb(CPUState *cpu)
 394 {
 395     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_IDLE);
 396 }
 397
 398 void qemu_plugin_vcpu_resume_cb(CPUState *cpu)
 399 {
 400     plugin_vcpu_cb__simple(cpu, QEMU_PLUGIN_EV_VCPU_RESUME);
 401 }
 402
 403 void qemu_plugin_register_vcpu_idle_cb(qemu_plugin_id_t id,
 404                                        qemu_plugin_vcpu_simple_cb_t cb)
 405 {
 406     plugin_register_cb(id, QEMU_PLUGIN_EV_VCPU_IDLE, cb);
 407 }
 408
 409 void qemu_plugin_register_vcpu_resume_cb(qemu_plugin_id_t id,
 410                                          qemu_plugin_vcpu_simple_cb_t cb)
 411 {
 412     plugin_register_cb(id, QEMU_PLUGIN_EV_VCPU_RESUME, cb);
 413 }
 414
 415 void qemu_plugin_register_flush_cb(qemu_plugin_id_t id,
 416                                    qemu_plugin_simple_cb_t cb)
 417 {
 418     plugin_register_cb(id, QEMU_PLUGIN_EV_FLUSH, cb);
 419 }
 420
 421 static bool free_dyn_cb_arr(void *p, uint32_t h, void *userp)
 422 {
 423     g_array_free((GArray *) p, true);
 424     return true;
 425 }
 426
 427 void qemu_plugin_flush_cb(void)
 428 {
 429     qht_iter_remove(&plugin.dyn_cb_arr_ht, free_dyn_cb_arr, NULL);
 430     qht_reset(&plugin.dyn_cb_arr_ht);
 431
 432     plugin_cb__simple(QEMU_PLUGIN_EV_FLUSH);
 433 }
 434
 435 void exec_inline_op(struct qemu_plugin_dyn_cb *cb)
 436 {
 437     uint64_t *val = cb->userp;
 438
 439     switch (cb->inline_insn.op) {
 440     case QEMU_PLUGIN_INLINE_ADD_U64:
 441         *val += cb->inline_insn.imm;
 442         break;
 443     default:
 444         g_assert_not_reached();
 445     }
 446 }
 447
 448 void qemu_plugin_vcpu_mem_cb(CPUState *cpu, uint64_t vaddr,
 449                              MemOpIdx oi, enum qemu_plugin_mem_rw rw)
 450 {
 451     GArray *arr = cpu->plugin_mem_cbs;
 452     size_t i;
 453
 454     if (arr == NULL) {
 455         return;
 456     }
 457     for (i = 0; i < arr->len; i++) {
 458         struct qemu_plugin_dyn_cb *cb =
 459             &g_array_index(arr, struct qemu_plugin_dyn_cb, i);
 460
 461         if (!(rw & cb->rw)) {
 462                 break;
 463         }
 464         switch (cb->type) {
 465         case PLUGIN_CB_REGULAR:
 466             cb->f.vcpu_mem(cpu->cpu_index, make_plugin_meminfo(oi, rw),
 467                            vaddr, cb->userp);
 468             break;
 469         case PLUGIN_CB_INLINE:
 470             exec_inline_op(cb);
 471             break;
 472         default:
 473             g_assert_not_reached();
 474         }
 475     }
 476 }
 477
 478 void qemu_plugin_atexit_cb(void)
 479 {
 480     plugin_cb__udata(QEMU_PLUGIN_EV_ATEXIT);
 481 }
 482
 483 void qemu_plugin_register_atexit_cb(qemu_plugin_id_t id,
 484                                     qemu_plugin_udata_cb_t cb,
 485                                     void *udata)
 486 {
 487     plugin_register_cb_udata(id, QEMU_PLUGIN_EV_ATEXIT, cb, udata);
 488 }
 489
 490 /*
 491  * Handle exit from linux-user. Unlike the normal atexit() mechanism
 492  * we need to handle the clean-up manually as it's possible threads
 493  * are still running. We need to remove all callbacks from code
 494  * generation, flush the current translations and then we can safely
 495  * trigger the exit callbacks.
 496  */
 497
 498 void qemu_plugin_user_exit(void)
 499 {
 500     enum qemu_plugin_event ev;
 501     CPUState *cpu;
 502
 503     /*
 504      * Locking order: we must acquire locks in an order that is consistent
 505      * with the one in fork_start(). That is:
 506      * - start_exclusive(), which acquires qemu_cpu_list_lock,
 507      *   must be called before acquiring plugin.lock.
 508      * - tb_flush(), which acquires mmap_lock(), must be called
 509      *   while plugin.lock is not held.
 510      */
 511     start_exclusive();
 512
 513     qemu_rec_mutex_lock(&plugin.lock);
 514     /* un-register all callbacks except the final AT_EXIT one */
 515     for (ev = 0; ev < QEMU_PLUGIN_EV_MAX; ev++) {
 516         if (ev != QEMU_PLUGIN_EV_ATEXIT) {
 517             struct qemu_plugin_cb *cb, *next;
 518
 519             QLIST_FOREACH_SAFE_RCU(cb, &plugin.cb_lists[ev], entry, next) {
 520                 plugin_unregister_cb__locked(cb->ctx, ev);
 521             }
 522         }
 523     }
 524     CPU_FOREACH(cpu) {
 525         qemu_plugin_disable_mem_helpers(cpu);
 526     }
 527     qemu_rec_mutex_unlock(&plugin.lock);
 528
 529     tb_flush(current_cpu);
 530     end_exclusive();
 531
 532     /* now it's safe to handle the exit case */
 533     qemu_plugin_atexit_cb();
 534 }
 535
 536 /*
 537  * Helpers for *-user to ensure locks are sane across fork() events.
 538  */
 539
 540 void qemu_plugin_user_prefork_lock(void)
 541 {
 542     qemu_rec_mutex_lock(&plugin.lock);
 543 }
 544
 545 void qemu_plugin_user_postfork(bool is_child)
 546 {
 547     if (is_child) {
 548         /* should we just reset via plugin_init? */
 549         qemu_rec_mutex_init(&plugin.lock);
 550     } else {
 551         qemu_rec_mutex_unlock(&plugin.lock);
 552     }
 553 }
 554
 555
 556 /*
 557  * Call this function after longjmp'ing to the main loop. It's possible that the
 558  * last instruction of a TB might have used helpers, and therefore the
 559  * "disable" instruction will never execute because it ended up as dead code.
 560  */
 561 void qemu_plugin_disable_mem_helpers(CPUState *cpu)
 562 {
 563     cpu->plugin_mem_cbs = NULL;
 564 }
 565
 566 static bool plugin_dyn_cb_arr_cmp(const void *ap, const void *bp)
 567 {
 568     return ap == bp;
 569 }
 570
 571 static void __attribute__((__constructor__)) plugin_init(void)
 572 {
 573     int i;
 574
 575     for (i = 0; i < QEMU_PLUGIN_EV_MAX; i++) {
 576         QLIST_INIT(&plugin.cb_lists[i]);
 577     }
 578     qemu_rec_mutex_init(&plugin.lock);
 579     plugin.id_ht = g_hash_table_new(g_int64_hash, g_int64_equal);
 580     plugin.cpu_ht = g_hash_table_new(g_int_hash, g_int_equal);
 581     QTAILQ_INIT(&plugin.ctxs);
 582     qht_init(&plugin.dyn_cb_arr_ht, plugin_dyn_cb_arr_cmp, 16,
 583              QHT_MODE_AUTO_RESIZE);
 584     atexit(qemu_plugin_atexit_cb);
 585 }