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