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