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 "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 static bool plugin_dyn_cb_arr_cmp(const void *ap, const void *bp) 556 { 557 return ap == bp; 558 } 559 560 static void __attribute__((__constructor__)) plugin_init(void) 561 { 562 int i; 563 564 for (i = 0; i < QEMU_PLUGIN_EV_MAX; i++) { 565 QLIST_INIT(&plugin.cb_lists[i]); 566 } 567 qemu_rec_mutex_init(&plugin.lock); 568 plugin.id_ht = g_hash_table_new(g_int64_hash, g_int64_equal); 569 plugin.cpu_ht = g_hash_table_new(g_int_hash, g_int_equal); 570 QTAILQ_INIT(&plugin.ctxs); 571 qht_init(&plugin.dyn_cb_arr_ht, plugin_dyn_cb_arr_cmp, 16, 572 QHT_MODE_AUTO_RESIZE); 573 atexit(qemu_plugin_atexit_cb); 574 } 575