malloc_debug_qemu.cpp revision 72bbd423579bb971dc06cdd3c06201faf3fe95e6
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29/* 30 * Contains implementation of memory allocation routines instrumented for 31 * usage in the emulator to detect memory allocation violations, such as 32 * memory leaks, buffer overruns, etc. 33 * Code, implemented here is intended to run in the emulated environment only, 34 * and serves simply as hooks into memory allocation routines. Main job of this 35 * code is to notify the emulator about memory being allocated/deallocated, 36 * providing information about each allocation. The idea is that emulator will 37 * keep list of currently allocated blocks, and, knowing boundaries of each 38 * block it will be able to verify that ld/st access to these blocks don't step 39 * over boundaries set for the user. To enforce that, each memory block 40 * allocated by this code is guarded with "prefix" and "suffix" areas, so 41 * every time emulator detects access to any of these guarding areas, it can be 42 * considered as access violation. 43 */ 44 45#include <stdlib.h> 46#include <stddef.h> 47#include <stdio.h> 48#include <fcntl.h> 49#include <sys/mman.h> 50#include <pthread.h> 51#include <unistd.h> 52#include <errno.h> 53#include "private/libc_logging.h" 54#include "malloc_debug_common.h" 55 56/* This file should be included into the build only when 57 * MALLOC_QEMU_INSTRUMENT macro is defined. */ 58#ifndef MALLOC_QEMU_INSTRUMENT 59#error MALLOC_QEMU_INSTRUMENT is not defined. 60#endif // !MALLOC_QEMU_INSTRUMENT 61 62/* Controls access violation test performed to make sure that we catch AVs 63 * all the time they occur. See test_access_violation for more info. This macro 64 * is used for internal testing purposes and should always be set to zero for 65 * the production builds. */ 66#define TEST_ACCESS_VIOLATIONS 0 67 68// ============================================================================= 69// Communication structures 70// ============================================================================= 71 72/* Describes memory block allocated from the heap. This structure is passed 73 * along with TRACE_DEV_REG_MALLOC event. This descriptor is used to inform 74 * the emulator about new memory block being allocated from the heap. The entire 75 * structure is initialized by the guest system before event is fired up. It is 76 * important to remember that same structure (an exact copy, except for 77 * replacing pointers with target_ulong) is also declared in the emulator's 78 * sources (file memcheck/memcheck_common.h). So, every time a change is made to 79 * any of these two declaration, another one must be also updated accordingly. 80 */ 81struct MallocDesc { 82 /* Pointer to the memory block actually allocated from the heap. Note that 83 * this is not the pointer that is returned to the malloc's caller. Pointer 84 * returned to the caller is calculated by adding value stored in this field 85 * to the value stored in prefix_size field of this structure. 86 */ 87 void* ptr; 88 89 /* Number of bytes requested by the malloc's caller. */ 90 uint32_t requested_bytes; 91 92 /* Byte size of the prefix data. Actual pointer returned to the malloc's 93 * caller is calculated by adding value stored in this field to the value 94 * stored in in the ptr field of this structure. 95 */ 96 uint32_t prefix_size; 97 98 /* Byte size of the suffix data. */ 99 uint32_t suffix_size; 100 101 /* Id of the process that initialized libc instance, in which allocation 102 * has occurred. This field is used by the emulator to report errors in 103 * the course of TRACE_DEV_REG_MALLOC event handling. In case of an error, 104 * emulator sets this field to zero (invalid value for a process ID). 105 */ 106 uint32_t libc_pid; 107 108 /* Id of the process in context of which allocation has occurred. 109 * Value in this field may differ from libc_pid value, if process that 110 * is doing allocation has been forked from the process that initialized 111 * libc instance. 112 */ 113 uint32_t allocator_pid; 114 115 /* Number of access violations detected on this allocation. */ 116 uint32_t av_count; 117}; 118 119/* Describes memory block info queried from emulator. This structure is passed 120 * along with TRACE_DEV_REG_QUERY_MALLOC event. When handling free and realloc 121 * calls, it is required that we have information about memory blocks that were 122 * actually allocated in previous calls to malloc, calloc, memalign, or realloc. 123 * Since we don't keep this information directly in the allocated block, but 124 * rather we keep it in the emulator, we need to query emulator for that 125 * information with TRACE_DEV_REG_QUERY_MALLOC query. The entire structure is 126 * initialized by the guest system before event is fired up. It is important to 127 * remember that same structure (an exact copy, except for replacing pointers 128 * with target_ulong) is also declared in the emulator's sources (file 129 * memcheck/memecheck_common.h). So, every time a change is made to any of these 130 * two declaration, another one must be also updated accordingly. 131 */ 132struct MallocDescQuery { 133 /* Pointer, for which information is queried. Note that this pointer doesn't 134 * have to be exact pointer returned to malloc's caller, but can point 135 * anywhere inside an allocated block, including guarding areas. Emulator 136 * will respond with information about allocated block that contains this 137 * pointer. 138 */ 139 const void* ptr; 140 141 /* Id of the process that initialized libc instance, in which this query 142 * is called. This field is used by the emulator to report errors in 143 * the course of TRACE_DEV_REG_QUERY_MALLOC event handling. In case of an 144 * error, emulator sets this field to zero (invalid value for a process ID). 145 */ 146 uint32_t libc_pid; 147 148 /* Process ID in context of which query is made. */ 149 uint32_t query_pid; 150 151 /* Code of the allocation routine, in context of which query has been made: 152 * 1 - free 153 * 2 - realloc 154 */ 155 uint32_t routine; 156 157 /* Address of memory allocation descriptor for the queried pointer. 158 * Descriptor, addressed by this field is initialized by the emulator in 159 * response to the query. 160 */ 161 MallocDesc* desc; 162}; 163 164/* Describes memory block that is being freed back to the heap. This structure 165 * is passed along with TRACE_DEV_REG_FREE_PTR event. The entire structure is 166 * initialized by the guest system before event is fired up. It is important to 167 * remember that same structure (an exact copy, except for replacing pointers 168 * with target_ulong) is also declared in the emulator's sources (file 169 * memcheck/memecheck_common.h). So, every time a change is made to any of these 170 * two declaration, another one must be also updated accordingly. 171 */ 172struct MallocFree { 173 /* Pointer to be freed. */ 174 void* ptr; 175 176 /* Id of the process that initialized libc instance, in which this free 177 * is called. This field is used by the emulator to report errors in 178 * the course of TRACE_DEV_REG_FREE_PTR event handling. In case of an 179 * error, emulator sets this field to zero (invalid value for a process ID). 180 */ 181 uint32_t libc_pid; 182 183 /* Process ID in context of which memory is being freed. */ 184 uint32_t free_pid; 185}; 186 187// ============================================================================= 188// Communication events 189// ============================================================================= 190 191/* Notifies the emulator that libc has been initialized for a process. 192 * Event's value parameter is PID for the process in context of which libc has 193 * been initialized. 194 */ 195#define TRACE_DEV_REG_LIBC_INIT 1536 196 197/* Notifies the emulator about new memory block been allocated. 198 * Event's value parameter points to MallocDesc instance that contains 199 * allocated block information. Note that 'libc_pid' field of the descriptor 200 * is used by emulator to report failure in handling this event. In case 201 * of a failure emulator will zero that field before completing this event. 202 */ 203#define TRACE_DEV_REG_MALLOC 1537 204 205/* Notifies the emulator about memory block being freed. 206 * Event's value parameter points to MallocFree descriptor that contains 207 * information about block that's being freed. Note that 'libc_pid' field 208 * of the descriptor is used by emulator to report failure in handling this 209 * event. In case of a failure emulator will zero that field before completing 210 * this event. 211 */ 212#define TRACE_DEV_REG_FREE_PTR 1538 213 214/* Queries the emulator about allocated memory block information. 215 * Event's value parameter points to MallocDescQuery descriptor that contains 216 * query parameters. Note that 'libc_pid' field of the descriptor is used by 217 * emulator to report failure in handling this event. In case of a failure 218 * emulator will zero that field before completing this event. 219 */ 220#define TRACE_DEV_REG_QUERY_MALLOC 1539 221 222/* Queries the emulator to print a string to its stdout. 223 * Event's value parameter points to a zero-terminated string to be printed. 224 */ 225#define TRACE_DEV_REG_PRINT_USER_STR 1540 226 227static void notify_qemu_string(const char* str); 228static void qemu_log(int prio, const char* fmt, ...); 229static void dump_malloc_descriptor(char* str, 230 size_t str_buf_size, 231 const MallocDesc* desc); 232 233// ============================================================================= 234// Macros 235// ============================================================================= 236 237/* Defines default size of allocation prefix. 238 * Note that we make prefix area quite large in order to increase chances of 239 * catching buffer overflow. */ 240#define DEFAULT_PREFIX_SIZE (malloc_alignment * 4) 241 242/* Defines default size of allocation suffix. 243 * Note that we make suffix area quite large in order to increase chances of 244 * catching buffer overflow. */ 245#define DEFAULT_SUFFIX_SIZE (malloc_alignment * 4) 246 247/* Debug tracing has been enabled by the emulator. */ 248#define DEBUG_TRACING_ENABLED 0x00000001 249/* Error tracing has been enabled by the emulator. */ 250#define ERROR_TRACING_ENABLED 0x00000002 251/* Info tracing has been enabled by the emulator. */ 252#define INFO_TRACING_ENABLED 0x00000004 253/* All tracing flags combined. */ 254#define ALL_TRACING_ENABLED (DEBUG_TRACING_ENABLED | \ 255 ERROR_TRACING_ENABLED | \ 256 INFO_TRACING_ENABLED) 257 258/* Prints a string to the emulator's stdout. 259 * In early stages of system loading, logging messages to logcat 260 * is not available, because ADB API has not been 261 * hooked up yet. So, in order to see such messages we need to print them to 262 * the emulator's stdout. 263 * Parameters passed to this macro are the same as parameters for printf 264 * routine. 265 */ 266#define TR(...) \ 267 do { \ 268 char tr_str[4096]; \ 269 snprintf(tr_str, sizeof(tr_str), __VA_ARGS__); \ 270 tr_str[sizeof(tr_str) - 1] = '\0'; \ 271 notify_qemu_string(&tr_str[0]); \ 272 } while (0) 273 274// ============================================================================= 275// Logging macros. Note that we simultaneously log messages to ADB and emulator. 276// ============================================================================= 277 278/* 279 * Helper macros for checking if particular trace level is enabled. 280 */ 281#define debug_LOG_ENABLED ((tracing_flags & DEBUG_TRACING_ENABLED) != 0) 282#define error_LOG_ENABLED ((tracing_flags & ERROR_TRACING_ENABLED) != 0) 283#define info_LOG_ENABLED ((tracing_flags & INFO_TRACING_ENABLED) != 0) 284#define tracing_enabled(type) (type##_LOG_ENABLED) 285 286/* 287 * Logging helper macros. 288 */ 289#define qemu_debug_log(format, ...) \ 290 do { \ 291 __libc_format_log(ANDROID_LOG_DEBUG, "memcheck", (format), ##__VA_ARGS__); \ 292 if (tracing_flags & DEBUG_TRACING_ENABLED) { \ 293 qemu_log(ANDROID_LOG_DEBUG, (format), ##__VA_ARGS__); \ 294 } \ 295 } while (0) 296 297#define qemu_error_log(format, ...) \ 298 do { \ 299 __libc_format_log(ANDROID_LOG_ERROR, "memcheck", (format), ##__VA_ARGS__); \ 300 if (tracing_flags & ERROR_TRACING_ENABLED) { \ 301 qemu_log(ANDROID_LOG_ERROR, (format), ##__VA_ARGS__); \ 302 } \ 303 } while (0) 304 305#define qemu_info_log(format, ...) \ 306 do { \ 307 __libc_format_log(ANDROID_LOG_INFO, "memcheck", (format), ##__VA_ARGS__); \ 308 if (tracing_flags & INFO_TRACING_ENABLED) { \ 309 qemu_log(ANDROID_LOG_INFO, (format), ##__VA_ARGS__); \ 310 } \ 311 } while (0) 312 313/* Logs message dumping MallocDesc instance at the end of the message. 314 * Param: 315 * type - Message type: debug, error, or info 316 * desc - MallocDesc instance to dump. 317 * fmt + rest - Formats message preceding dumped descriptor. 318*/ 319#define log_mdesc(type, desc, fmt, ...) \ 320 do { \ 321 if (tracing_enabled(type)) { \ 322 char log_str[4096]; \ 323 __libc_format_buffer(log_str, sizeof(log_str), fmt, ##__VA_ARGS__); \ 324 log_str[sizeof(log_str) - 1] = '\0'; \ 325 size_t str_len = strlen(log_str); \ 326 dump_malloc_descriptor(log_str + str_len, \ 327 sizeof(log_str) - str_len, \ 328 (desc)); \ 329 type##_log("%s", log_str); \ 330 } \ 331 } while (0) 332 333// ============================================================================= 334// Static data 335// ============================================================================= 336 337/* Emulator's magic page address. 338 * This page (mapped on /dev/qemu_trace device) is used to fire up events 339 * in the emulator. */ 340static volatile void* qtrace = NULL; 341 342/* Cached PID of the process in context of which this libc instance 343 * has been initialized. */ 344static uint32_t malloc_pid = 0; 345 346/* Memory allocation alignment that is used in the malloc implementation. 347 * This variable is updated by memcheck_initialize routine. */ 348static uint32_t malloc_alignment = 8; 349 350/* Tracing flags. These flags control which types of logging messages are 351 * enabled by the emulator. See XXX_TRACING_ENABLED for the values of flags 352 * stored in this variable. This variable is updated by memcheck_initialize 353 * routine. */ 354static uint32_t tracing_flags = 0; 355 356// ============================================================================= 357// Static routines 358// ============================================================================= 359 360/* Gets pointer, returned to malloc caller for the given allocation decriptor. 361 * Param: 362 * desc - Allocation descriptor. 363 * Return: 364 * Pointer to the allocated memory returned to the malloc caller. 365 */ 366static inline void* mallocdesc_user_ptr(const MallocDesc* desc) { 367 return static_cast<char*>(desc->ptr) + desc->prefix_size; 368} 369 370/* Gets size of memory block actually allocated from the heap for the given 371 * allocation decriptor. 372 * Param: 373 * desc - Allocation descriptor. 374 * Return: 375 * Size of memory block actually allocated from the heap. 376 */ 377static inline uint32_t mallocdesc_alloc_size(const MallocDesc* desc) { 378 return desc->prefix_size + desc->requested_bytes + desc->suffix_size; 379} 380 381/* Gets pointer to the end of the allocated block for the given descriptor. 382 * Param: 383 * desc - Descriptor for the memory block, allocated in malloc handler. 384 * Return: 385 * Pointer to the end of (one byte past) the allocated block. 386 */ 387static inline void* mallocdesc_alloc_end(const MallocDesc* desc) { 388 return static_cast<char*>(desc->ptr) + mallocdesc_alloc_size(desc); 389} 390 391/* Fires up an event in the emulator. 392 * Param: 393 * code - Event code (one of the TRACE_DEV_XXX). 394 * val - Event's value parameter. 395 */ 396static inline void notify_qemu(uint32_t code, uintptr_t val) { 397 if (NULL != qtrace) { 398 *(volatile uintptr_t*)((uintptr_t)qtrace + ((code - 1024) << 2)) = val; 399 } 400} 401 402/* Prints a zero-terminated string to the emulator's stdout (fires up 403 * TRACE_DEV_REG_PRINT_USER_STR event in the emulator). 404 * Param: 405 * str - Zero-terminated string to print. 406 */ 407static void notify_qemu_string(const char* str) { 408 if (str != NULL) { 409 notify_qemu(TRACE_DEV_REG_PRINT_USER_STR, reinterpret_cast<uintptr_t>(str)); 410 } 411} 412 413/* Fires up TRACE_DEV_REG_LIBC_INIT event in the emulator. 414 * Param: 415 * pid - ID of the process that initialized libc. 416 */ 417static void notify_qemu_libc_initialized(uint32_t pid) { 418 notify_qemu(TRACE_DEV_REG_LIBC_INIT, pid); 419} 420 421/* Fires up TRACE_DEV_REG_MALLOC event in the emulator. 422 * Param: 423 * desc - Pointer to MallocDesc instance containing allocated block 424 * information. 425 * Return: 426 * Zero on success, or -1 on failure. Note that on failure libc_pid field of 427 * the desc parameter passed to this routine has been zeroed out by the 428 * emulator. 429 */ 430static inline int notify_qemu_malloc(volatile MallocDesc* desc) { 431 desc->libc_pid = malloc_pid; 432 desc->allocator_pid = getpid(); 433 desc->av_count = 0; 434 notify_qemu(TRACE_DEV_REG_MALLOC, reinterpret_cast<uintptr_t>(desc)); 435 436 /* Emulator reports failure by zeroing libc_pid field of the 437 * descriptor. */ 438 return desc->libc_pid != 0 ? 0 : -1; 439} 440 441/* Fires up TRACE_DEV_REG_FREE_PTR event in the emulator. 442 * Param: 443 * ptr - Pointer to the memory block that's being freed. 444 * Return: 445 * Zero on success, or -1 on failure. 446 */ 447static inline int notify_qemu_free(void* ptr_to_free) { 448 volatile MallocFree free_desc; 449 450 free_desc.ptr = ptr_to_free; 451 free_desc.libc_pid = malloc_pid; 452 free_desc.free_pid = getpid(); 453 notify_qemu(TRACE_DEV_REG_FREE_PTR, reinterpret_cast<uintptr_t>(&free_desc)); 454 455 /* Emulator reports failure by zeroing libc_pid field of the 456 * descriptor. */ 457 return free_desc.libc_pid != 0 ? 0 : -1; 458} 459 460/* Fires up TRACE_DEV_REG_QUERY_MALLOC event in the emulator. 461 * Param: 462 * ptr - Pointer to request allocation information for. 463 * desc - Pointer to MallocDesc instance that will receive allocation 464 * information. 465 * routine - Code of the allocation routine, in context of which query is made: 466 * 1 - free 467 * 2 - realloc 468 * Return: 469 * Zero on success, or -1 on failure. 470 */ 471static inline int query_qemu_malloc_info(const void* ptr, MallocDesc* desc, uint32_t routine) { 472 volatile MallocDescQuery query; 473 474 query.ptr = ptr; 475 query.libc_pid = malloc_pid; 476 query.query_pid = getpid(); 477 query.routine = routine; 478 query.desc = desc; 479 notify_qemu(TRACE_DEV_REG_QUERY_MALLOC, reinterpret_cast<uintptr_t>(&query)); 480 481 /* Emulator reports failure by zeroing libc_pid field of the 482 * descriptor. */ 483 return query.libc_pid != 0 ? 0 : -1; 484} 485 486/* Logs a message to emulator's stdout. 487 * Param: 488 * prio - Message priority (debug, info, or error) 489 * fmt + rest - Message format and parameters. 490 */ 491static void qemu_log(int prio, const char* fmt, ...) { 492 va_list ap; 493 char buf[4096]; 494 const char* prefix; 495 496 /* Choose message prefix depending on the priority value. */ 497 switch (prio) { 498 case ANDROID_LOG_ERROR: 499 if (!tracing_enabled(error)) { 500 return; 501 } 502 prefix = "E"; 503 break; 504 case ANDROID_LOG_INFO: 505 if (!tracing_enabled(info)) { 506 return; 507 } 508 prefix = "I"; 509 break; 510 case ANDROID_LOG_DEBUG: 511 default: 512 if (!tracing_enabled(debug)) { 513 return; 514 } 515 prefix = "D"; 516 break; 517 } 518 519 va_start(ap, fmt); 520 vsnprintf(buf, sizeof(buf), fmt, ap); 521 va_end(ap); 522 buf[sizeof(buf) - 1] = '\0'; 523 524 TR("%s/memcheck: %s\n", prefix, buf); 525} 526 527/* Dumps content of memory allocation descriptor to a string. 528 * Param: 529 * str - String to dump descriptor to. 530 * str_buf_size - Size of string's buffer. 531 * desc - Descriptor to dump. 532 */ 533static void dump_malloc_descriptor(char* str, size_t str_buf_size, const MallocDesc* desc) { 534 if (str_buf_size) { 535 snprintf(str, str_buf_size, 536 "MDesc: %p: %p <-> %p [%u + %u + %u] by pid=%03u in libc_pid=%03u", 537 mallocdesc_user_ptr(desc), desc->ptr, 538 mallocdesc_alloc_end(desc), desc->prefix_size, 539 desc->requested_bytes, desc->suffix_size, desc->allocator_pid, 540 desc->libc_pid); 541 str[str_buf_size - 1] = '\0'; 542 } 543} 544 545#if TEST_ACCESS_VIOLATIONS 546/* Causes an access violation on allocation descriptor, and verifies that 547 * violation has been detected by memory checker in the emulator. 548 */ 549static void test_access_violation(const MallocDesc* desc) { 550 MallocDesc desc_chk; 551 char ch; 552 volatile char* prefix = (volatile char*)desc->ptr; 553 volatile char* suffix = (volatile char*)mallocdesc_user_ptr(desc) + 554 desc->requested_bytes; 555 /* We're causing AV by reading from the prefix and suffix areas of the 556 * allocated block. This should produce two access violations, so when we 557 * get allocation descriptor from QEMU, av_counter should be bigger than 558 * av_counter of the original descriptor by 2. */ 559 ch = *prefix; 560 ch = *suffix; 561 if (!query_qemu_malloc_info(mallocdesc_user_ptr(desc), &desc_chk, 2) && 562 desc_chk.av_count != (desc->av_count + 2)) { 563 log_mdesc(error, &desc_chk, 564 "<libc_pid=%03u, pid=%03u>: malloc: Access violation test failed:\n" 565 "Expected violations count %u is not equal to the actually reported %u", 566 malloc_pid, getpid(), desc->av_count + 2, 567 desc_chk.av_count); 568 } 569} 570#endif // TEST_ACCESS_VIOLATIONS 571 572// ============================================================================= 573// API routines 574// ============================================================================= 575 576extern "C" void* qemu_instrumented_malloc(size_t bytes); 577extern "C" void qemu_instrumented_free(void* mem); 578extern "C" void* qemu_instrumented_calloc(size_t n_elements, size_t elem_size); 579extern "C" void* qemu_instrumented_realloc(void* mem, size_t bytes); 580extern "C" void* qemu_instrumented_memalign(size_t alignment, size_t bytes); 581extern "C" size_t qemu_instrumented_malloc_usable_size(const void* mem); 582 583/* Initializes malloc debugging instrumentation for the emulator. 584 * This routine is called from malloc_init_impl routine implemented in 585 * bionic/libc/bionic/malloc_debug_common.c when malloc debugging gets 586 * initialized for a process. The way malloc debugging implementation is 587 * done, it is guaranteed that this routine will be called just once per 588 * process. 589 * Return: 590 * 0 on success, or -1 on failure. 591*/ 592extern "C" int malloc_debug_initialize() { 593 /* We will be using emulator's magic page to report memory allocation 594 * activities. In essence, what magic page does, it translates writes to 595 * the memory mapped spaces into writes to an I/O port that emulator 596 * "listens to" on the other end. Note that until we open and map that 597 * device, logging to emulator's stdout will not be available. */ 598 int fd = open("/dev/qemu_trace", O_RDWR); 599 if (fd < 0) { 600 error_log("Unable to open /dev/qemu_trace"); 601 return -1; 602 } else { 603 qtrace = mmap(NULL, PAGESIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 604 close(fd); 605 606 if (qtrace == MAP_FAILED) { 607 qtrace = NULL; 608 error_log("Unable to mmap /dev/qemu_trace"); 609 return -1; 610 } 611 } 612 613 /* Cache pid of the process this library has been initialized for. */ 614 malloc_pid = getpid(); 615 616 return 0; 617} 618 619/* Completes malloc debugging instrumentation for the emulator. 620 * Note that this routine is called after successful return from 621 * malloc_debug_initialize, which means that connection to the emulator via 622 * "magic page" has been established. 623 * Param: 624 * alignment - Alignment requirement set for memiry allocations. 625 * memcheck_param - Emulator's -memcheck option parameters. This string 626 * contains abbreviation for guest events that are enabled for tracing. 627 * Return: 628 * 0 on success, or -1 on failure. 629*/ 630extern "C" int memcheck_initialize(int alignment, const char* memcheck_param) { 631 malloc_alignment = alignment; 632 633 /* Parse -memcheck parameter for the guest tracing flags. */ 634 while (*memcheck_param != '\0') { 635 switch (*memcheck_param) { 636 case 'a': 637 // Enable all messages from the guest. 638 tracing_flags |= ALL_TRACING_ENABLED; 639 break; 640 case 'd': 641 // Enable debug messages from the guest. 642 tracing_flags |= DEBUG_TRACING_ENABLED; 643 break; 644 case 'e': 645 // Enable error messages from the guest. 646 tracing_flags |= ERROR_TRACING_ENABLED; 647 break; 648 case 'i': 649 // Enable info messages from the guest. 650 tracing_flags |= INFO_TRACING_ENABLED; 651 break; 652 default: 653 break; 654 } 655 if (tracing_flags == ALL_TRACING_ENABLED) { 656 break; 657 } 658 memcheck_param++; 659 } 660 661 notify_qemu_libc_initialized(malloc_pid); 662 663 qemu_debug_log("Instrumented for pid=%03u: malloc=%p, free=%p, calloc=%p, realloc=%p, memalign=%p", 664 malloc_pid, qemu_instrumented_malloc, qemu_instrumented_free, 665 qemu_instrumented_calloc, qemu_instrumented_realloc, 666 qemu_instrumented_memalign); 667 668 return 0; 669} 670 671/* This routine serves as entry point for 'malloc'. 672 * Primary responsibility of this routine is to allocate requested number of 673 * bytes (plus prefix, and suffix guards), and report allocation to the 674 * emulator. 675 */ 676extern "C" void* qemu_instrumented_malloc(size_t bytes) { 677 MallocDesc desc; 678 679 /* Initialize block descriptor and allocate memory. Note that malloc 680 * returns a valid pointer on zero allocation. Lets mimic this behavior. */ 681 desc.prefix_size = DEFAULT_PREFIX_SIZE; 682 desc.requested_bytes = bytes; 683 desc.suffix_size = DEFAULT_SUFFIX_SIZE; 684 desc.ptr = Malloc(malloc)(mallocdesc_alloc_size(&desc)); 685 if (desc.ptr == NULL) { 686 qemu_error_log("<libc_pid=%03u, pid=%03u> malloc(%zd): malloc(%u) failed.", 687 malloc_pid, getpid(), bytes, mallocdesc_alloc_size(&desc)); 688 return NULL; 689 } 690 691 // Fire up event in the emulator. 692 if (notify_qemu_malloc(&desc)) { 693 log_mdesc(error, &desc, "<libc_pid=%03u, pid=%03u>: malloc: notify_malloc failed for ", 694 malloc_pid, getpid()); 695 Malloc(free)(desc.ptr); 696 return NULL; 697 } else { 698#if TEST_ACCESS_VIOLATIONS 699 test_access_violation(&desc); 700#endif // TEST_ACCESS_VIOLATIONS 701 log_mdesc(info, &desc, "+++ <libc_pid=%03u, pid=%03u> malloc(%zd) -> ", 702 malloc_pid, getpid(), bytes); 703 return mallocdesc_user_ptr(&desc); 704 } 705} 706 707/* This routine serves as entry point for 'malloc'. 708 * Primary responsibility of this routine is to free requested memory, and 709 * report free block to the emulator. 710 */ 711extern "C" void qemu_instrumented_free(void* mem) { 712 MallocDesc desc; 713 714 if (mem == NULL) { 715 // Just let go NULL free 716 Malloc(free)(mem); 717 return; 718 } 719 720 // Query emulator for the freeing block information. 721 if (query_qemu_malloc_info(mem, &desc, 1)) { 722 error_log("<libc_pid=%03u, pid=%03u>: free(%p) query_info failed.", 723 malloc_pid, getpid(), mem); 724 return; 725 } 726 727#if TEST_ACCESS_VIOLATIONS 728 test_access_violation(&desc); 729#endif // TEST_ACCESS_VIOLATIONS 730 731 /* Make sure that pointer that's being freed matches what we expect 732 * for this memory block. Note that this violation should be already 733 * caught in the emulator. */ 734 if (mem != mallocdesc_user_ptr(&desc)) { 735 log_mdesc(error, &desc, "<libc_pid=%03u, pid=%03u>: free(%p) is invalid for ", 736 malloc_pid, getpid(), mem); 737 return; 738 } 739 740 // Fire up event in the emulator and free block that was actually allocated. 741 if (notify_qemu_free(mem)) { 742 log_mdesc(error, &desc, "<libc_pid=%03u, pid=%03u>: free(%p) notify_free failed for ", 743 malloc_pid, getpid(), mem); 744 } else { 745 log_mdesc(info, &desc, "--- <libc_pid=%03u, pid=%03u> free(%p) -> ", 746 malloc_pid, getpid(), mem); 747 Malloc(free)(desc.ptr); 748 } 749} 750 751/* This routine serves as entry point for 'calloc'. 752 * This routine behaves similarly to qemu_instrumented_malloc. 753 */ 754extern "C" void* qemu_instrumented_calloc(size_t n_elements, size_t elem_size) { 755 if (n_elements == 0 || elem_size == 0) { 756 // Just let go zero bytes allocation. 757 qemu_info_log("::: <libc_pid=%03u, pid=%03u>: Zero calloc redir to malloc", 758 malloc_pid, getpid()); 759 return qemu_instrumented_malloc(0); 760 } 761 762 /* Fail on overflow - just to be safe even though this code runs only 763 * within the debugging C library, not the production one */ 764 if (n_elements && MAX_SIZE_T / n_elements < elem_size) { 765 return NULL; 766 } 767 768 MallocDesc desc; 769 770 /* Calculating prefix size. The trick here is to make sure that 771 * first element (returned to the caller) is properly aligned. */ 772 if (DEFAULT_PREFIX_SIZE >= elem_size) { 773 /* If default alignment is bigger than element size, we will 774 * set our prefix size to the default alignment size. */ 775 desc.prefix_size = DEFAULT_PREFIX_SIZE; 776 /* For the suffix we will use whatever bytes remain from the prefix 777 * allocation size, aligned to the size of an element, plus the usual 778 * default suffix size. */ 779 desc.suffix_size = (DEFAULT_PREFIX_SIZE % elem_size) + 780 DEFAULT_SUFFIX_SIZE; 781 } else { 782 /* Make sure that prefix, and suffix sizes is at least elem_size, 783 * and first element returned to the caller is properly aligned. */ 784 desc.prefix_size = elem_size + DEFAULT_PREFIX_SIZE - 1; 785 desc.prefix_size &= ~(malloc_alignment - 1); 786 desc.suffix_size = DEFAULT_SUFFIX_SIZE; 787 } 788 desc.requested_bytes = n_elements * elem_size; 789 size_t total_size = desc.requested_bytes + desc.prefix_size + desc.suffix_size; 790 size_t total_elements = total_size / elem_size; 791 total_size %= elem_size; 792 if (total_size != 0) { 793 // Add extra to the suffix area. 794 total_elements++; 795 desc.suffix_size += (elem_size - total_size); 796 } 797 desc.ptr = Malloc(calloc)(total_elements, elem_size); 798 if (desc.ptr == NULL) { 799 error_log("<libc_pid=%03u, pid=%03u> calloc: calloc(%zd(%zd), %zd) (prx=%u, sfx=%u) failed.", 800 malloc_pid, getpid(), n_elements, total_elements, elem_size, 801 desc.prefix_size, desc.suffix_size); 802 return NULL; 803 } 804 805 if (notify_qemu_malloc(&desc)) { 806 log_mdesc(error, &desc, "<libc_pid=%03u, pid=%03u>: calloc(%zd(%zd), %zd): notify_malloc failed for ", 807 malloc_pid, getpid(), n_elements, total_elements, elem_size); 808 Malloc(free)(desc.ptr); 809 return NULL; 810 } else { 811#if TEST_ACCESS_VIOLATIONS 812 test_access_violation(&desc); 813#endif // TEST_ACCESS_VIOLATIONS 814 log_mdesc(info, &desc, "### <libc_pid=%03u, pid=%03u> calloc(%zd(%zd), %zd) -> ", 815 malloc_pid, getpid(), n_elements, total_elements, elem_size); 816 return mallocdesc_user_ptr(&desc); 817 } 818} 819 820/* This routine serves as entry point for 'realloc'. 821 * This routine behaves similarly to qemu_instrumented_free + 822 * qemu_instrumented_malloc. Note that this modifies behavior of "shrinking" an 823 * allocation, but overall it doesn't seem to matter, as caller of realloc 824 * should not expect that pointer returned after shrinking will remain the same. 825 */ 826extern "C" void* qemu_instrumented_realloc(void* mem, size_t bytes) { 827 MallocDesc new_desc; 828 MallocDesc cur_desc; 829 size_t to_copy; 830 void* ret; 831 832 if (mem == NULL) { 833 // Nothing to realloc. just do regular malloc. 834 qemu_info_log("::: <libc_pid=%03u, pid=%03u>: realloc(%p, %zd) redir to malloc", 835 malloc_pid, getpid(), mem, bytes); 836 return qemu_instrumented_malloc(bytes); 837 } 838 839 if (bytes == 0) { 840 // This is a "free" condition. 841 qemu_info_log("::: <libc_pid=%03u, pid=%03u>: realloc(%p, %zd) redir to free and malloc", 842 malloc_pid, getpid(), mem, bytes); 843 qemu_instrumented_free(mem); 844 845 // This is what realloc does for a "free" realloc. 846 return NULL; 847 } 848 849 // Query emulator for the reallocating block information. 850 if (query_qemu_malloc_info(mem, &cur_desc, 2)) { 851 // Note that this violation should be already caught in the emulator. 852 error_log("<libc_pid=%03u, pid=%03u>: realloc(%p, %zd) query_info failed.", 853 malloc_pid, getpid(), mem, bytes); 854 return NULL; 855 } 856 857#if TEST_ACCESS_VIOLATIONS 858 test_access_violation(&cur_desc); 859#endif // TEST_ACCESS_VIOLATIONS 860 861 /* Make sure that reallocating pointer value is what we would expect 862 * for this memory block. Note that this violation should be already caught 863 * in the emulator.*/ 864 if (mem != mallocdesc_user_ptr(&cur_desc)) { 865 log_mdesc(error, &cur_desc, "<libc_pid=%03u, pid=%03u>: realloc(%p, %zd) is invalid for ", 866 malloc_pid, getpid(), mem, bytes); 867 return NULL; 868 } 869 870 /* TODO: We're a bit inefficient here, always allocating new block from 871 * the heap. If this realloc shrinks current buffer, we can just do the 872 * shrinking "in place", adjusting suffix_size in the allocation descriptor 873 * for this block that is stored in the emulator. */ 874 875 // Initialize descriptor for the new block. 876 new_desc.prefix_size = DEFAULT_PREFIX_SIZE; 877 new_desc.requested_bytes = bytes; 878 new_desc.suffix_size = DEFAULT_SUFFIX_SIZE; 879 new_desc.ptr = Malloc(malloc)(mallocdesc_alloc_size(&new_desc)); 880 if (new_desc.ptr == NULL) { 881 log_mdesc(error, &cur_desc, "<libc_pid=%03u, pid=%03u>: realloc(%p, %zd): malloc(%u) failed on ", 882 malloc_pid, getpid(), mem, bytes, 883 mallocdesc_alloc_size(&new_desc)); 884 return NULL; 885 } 886 ret = mallocdesc_user_ptr(&new_desc); 887 888 // Copy user data from old block to the new one. 889 to_copy = bytes < cur_desc.requested_bytes ? bytes : 890 cur_desc.requested_bytes; 891 if (to_copy != 0) { 892 memcpy(ret, mallocdesc_user_ptr(&cur_desc), to_copy); 893 } 894 895 // Register new block with emulator. 896 if (notify_qemu_malloc(&new_desc)) { 897 log_mdesc(error, &new_desc, "<libc_pid=%03u, pid=%03u>: realloc(%p, %zd) notify_malloc failed -> ", 898 malloc_pid, getpid(), mem, bytes); 899 log_mdesc(error, &cur_desc, " <- "); 900 Malloc(free)(new_desc.ptr); 901 return NULL; 902 } 903 904#if TEST_ACCESS_VIOLATIONS 905 test_access_violation(&new_desc); 906#endif // TEST_ACCESS_VIOLATIONS 907 908 // Free old block. 909 if (notify_qemu_free(mem)) { 910 log_mdesc(error, &cur_desc, "<libc_pid=%03u, pid=%03u>: realloc(%p, %zd): notify_free failed for ", 911 malloc_pid, getpid(), mem, bytes); 912 /* Since we registered new decriptor with the emulator, we need 913 * to unregister it before freeing newly allocated block. */ 914 notify_qemu_free(mallocdesc_user_ptr(&new_desc)); 915 Malloc(free)(new_desc.ptr); 916 return NULL; 917 } 918 Malloc(free)(cur_desc.ptr); 919 920 log_mdesc(info, &new_desc, "=== <libc_pid=%03u, pid=%03u>: realloc(%p, %zd) -> ", 921 malloc_pid, getpid(), mem, bytes); 922 log_mdesc(info, &cur_desc, " <- "); 923 924 return ret; 925} 926 927/* This routine serves as entry point for 'memalign'. 928 * This routine behaves similarly to qemu_instrumented_malloc. 929 */ 930extern "C" void* qemu_instrumented_memalign(size_t alignment, size_t bytes) { 931 MallocDesc desc; 932 933 if (bytes == 0) { 934 // Just let go zero bytes allocation. 935 qemu_info_log("::: <libc_pid=%03u, pid=%03u>: memalign(%zx, %zd) redir to malloc", 936 malloc_pid, getpid(), alignment, bytes); 937 return qemu_instrumented_malloc(0); 938 } 939 940 /* Prefix size for aligned allocation must be equal to the alignment used 941 * for allocation in order to ensure proper alignment of the returned 942 * pointer, in case that alignment requirement is greater than prefix 943 * size. */ 944 desc.prefix_size = alignment > DEFAULT_PREFIX_SIZE ? alignment : 945 DEFAULT_PREFIX_SIZE; 946 desc.requested_bytes = bytes; 947 desc.suffix_size = DEFAULT_SUFFIX_SIZE; 948 desc.ptr = Malloc(memalign)(desc.prefix_size, mallocdesc_alloc_size(&desc)); 949 if (desc.ptr == NULL) { 950 error_log("<libc_pid=%03u, pid=%03u> memalign(%zx, %zd): malloc(%u) failed.", 951 malloc_pid, getpid(), alignment, bytes, 952 mallocdesc_alloc_size(&desc)); 953 return NULL; 954 } 955 if (notify_qemu_malloc(&desc)) { 956 log_mdesc(error, &desc, "<libc_pid=%03u, pid=%03u>: memalign(%zx, %zd): notify_malloc failed for ", 957 malloc_pid, getpid(), alignment, bytes); 958 Malloc(free)(desc.ptr); 959 return NULL; 960 } 961 962#if TEST_ACCESS_VIOLATIONS 963 test_access_violation(&desc); 964#endif // TEST_ACCESS_VIOLATIONS 965 966 log_mdesc(info, &desc, "@@@ <libc_pid=%03u, pid=%03u> memalign(%zx, %zd) -> ", 967 malloc_pid, getpid(), alignment, bytes); 968 return mallocdesc_user_ptr(&desc); 969} 970 971extern "C" size_t qemu_instrumented_malloc_usable_size(const void* mem) { 972 MallocDesc cur_desc; 973 974 // Query emulator for the reallocating block information. 975 if (query_qemu_malloc_info(mem, &cur_desc, 2)) { 976 // Note that this violation should be already caught in the emulator. 977 error_log("<libc_pid=%03u, pid=%03u>: malloc_usable_size(%p) query_info failed.", 978 malloc_pid, getpid(), mem); 979 return 0; 980 } 981 982 /* Make sure that reallocating pointer value is what we would expect 983 * for this memory block. Note that this violation should be already caught 984 * in the emulator.*/ 985 if (mem != mallocdesc_user_ptr(&cur_desc)) { 986 log_mdesc(error, &cur_desc, "<libc_pid=%03u, pid=%03u>: malloc_usable_size(%p) is invalid for ", 987 malloc_pid, getpid(), mem); 988 return 0; 989 } 990 991 /* during instrumentation, we can't really report anything more than requested_bytes */ 992 return cur_desc.requested_bytes; 993} 994