diff options
Diffstat (limited to 'memory/replace/logalloc/LogAlloc.cpp')
| -rw-r--r-- | memory/replace/logalloc/LogAlloc.cpp | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/memory/replace/logalloc/LogAlloc.cpp b/memory/replace/logalloc/LogAlloc.cpp new file mode 100644 index 0000000000..a976b0c674 --- /dev/null +++ b/memory/replace/logalloc/LogAlloc.cpp @@ -0,0 +1,238 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include <cstdlib> +#include <fcntl.h> + +#ifdef _WIN32 +# include <windows.h> +# include <io.h> +# include <process.h> +#else +# include <unistd.h> +# include <pthread.h> +#endif + +#include "replace_malloc.h" +#include "FdPrintf.h" +#include "Mutex.h" + +static malloc_table_t sFuncs; +static intptr_t sFd = 0; +static bool sStdoutOrStderr = false; + +static Mutex sMutex MOZ_UNANNOTATED; + +#ifndef _WIN32 +static void prefork() MOZ_NO_THREAD_SAFETY_ANALYSIS { sMutex.Lock(); } +static void postfork_parent() MOZ_NO_THREAD_SAFETY_ANALYSIS { sMutex.Unlock(); } +static void postfork_child() { sMutex.Init(); } +#endif + +static size_t GetPid() { return size_t(getpid()); } + +static size_t GetTid() { +#if defined(_WIN32) + return size_t(GetCurrentThreadId()); +#else + return size_t(pthread_self()); +#endif +} + +#ifdef ANDROID +/* Android doesn't have pthread_atfork defined in pthread.h */ +extern "C" MOZ_EXPORT int pthread_atfork(void (*)(void), void (*)(void), + void (*)(void)); +#endif + +class LogAllocBridge : public ReplaceMallocBridge { + virtual void InitDebugFd(mozilla::DebugFdRegistry& aRegistry) override { + if (!sStdoutOrStderr) { + aRegistry.RegisterHandle(sFd); + } + } +}; + +/* Do a simple, text-form, log of all calls to replace-malloc functions. + * Use locking to guarantee that an allocation that did happen is logged + * before any other allocation/free happens. + */ + +static void* replace_malloc(size_t aSize) { + MutexAutoLock lock(sMutex); + void* ptr = sFuncs.malloc(aSize); + FdPrintf(sFd, "%zu %zu malloc(%zu)=%p\n", GetPid(), GetTid(), aSize, ptr); + return ptr; +} + +static int replace_posix_memalign(void** aPtr, size_t aAlignment, + size_t aSize) { + MutexAutoLock lock(sMutex); + int ret = sFuncs.posix_memalign(aPtr, aAlignment, aSize); + FdPrintf(sFd, "%zu %zu posix_memalign(%zu,%zu)=%p\n", GetPid(), GetTid(), + aAlignment, aSize, (ret == 0) ? *aPtr : nullptr); + return ret; +} + +static void* replace_aligned_alloc(size_t aAlignment, size_t aSize) { + MutexAutoLock lock(sMutex); + void* ptr = sFuncs.aligned_alloc(aAlignment, aSize); + FdPrintf(sFd, "%zu %zu aligned_alloc(%zu,%zu)=%p\n", GetPid(), GetTid(), + aAlignment, aSize, ptr); + return ptr; +} + +static void* replace_calloc(size_t aNum, size_t aSize) { + MutexAutoLock lock(sMutex); + void* ptr = sFuncs.calloc(aNum, aSize); + FdPrintf(sFd, "%zu %zu calloc(%zu,%zu)=%p\n", GetPid(), GetTid(), aNum, aSize, + ptr); + return ptr; +} + +static void* replace_realloc(void* aPtr, size_t aSize) { + MutexAutoLock lock(sMutex); + void* new_ptr = sFuncs.realloc(aPtr, aSize); + FdPrintf(sFd, "%zu %zu realloc(%p,%zu)=%p\n", GetPid(), GetTid(), aPtr, aSize, + new_ptr); + return new_ptr; +} + +static void replace_free(void* aPtr) { + MutexAutoLock lock(sMutex); + FdPrintf(sFd, "%zu %zu free(%p)\n", GetPid(), GetTid(), aPtr); + sFuncs.free(aPtr); +} + +static void* replace_memalign(size_t aAlignment, size_t aSize) { + MutexAutoLock lock(sMutex); + void* ptr = sFuncs.memalign(aAlignment, aSize); + FdPrintf(sFd, "%zu %zu memalign(%zu,%zu)=%p\n", GetPid(), GetTid(), + aAlignment, aSize, ptr); + return ptr; +} + +static void* replace_valloc(size_t aSize) { + MutexAutoLock lock(sMutex); + void* ptr = sFuncs.valloc(aSize); + FdPrintf(sFd, "%zu %zu valloc(%zu)=%p\n", GetPid(), GetTid(), aSize, ptr); + return ptr; +} + +static void replace_jemalloc_stats(jemalloc_stats_t* aStats, + jemalloc_bin_stats_t* aBinStats) { + MutexAutoLock lock(sMutex); + sFuncs.jemalloc_stats_internal(aStats, aBinStats); + FdPrintf(sFd, "%zu %zu jemalloc_stats()\n", GetPid(), GetTid()); +} + +void replace_init(malloc_table_t* aTable, ReplaceMallocBridge** aBridge) { + /* Initialize output file descriptor from the MALLOC_LOG environment + * variable. Numbers up to 9999 are considered as a preopened file + * descriptor number. Other values are considered as a file name. */ +#ifdef _WIN32 + wchar_t* log = _wgetenv(L"MALLOC_LOG"); +#else + char* log = getenv("MALLOC_LOG"); +#endif + if (log && *log) { + int fd = 0; + const auto* fd_num = log; + while (*fd_num) { + /* Reject non digits. */ + if (*fd_num < '0' || *fd_num > '9') { + fd = -1; + break; + } + fd = fd * 10 + (*fd_num - '0'); + /* Reject values >= 10000. */ + if (fd >= 10000) { + fd = -1; + break; + } + fd_num++; + } + if (fd == 1 || fd == 2) { + sStdoutOrStderr = true; + } +#ifdef _WIN32 + // See comment in FdPrintf.h as to why CreateFile is used. + HANDLE handle; + if (fd > 0) { + handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd)); + } else { + handle = + CreateFileW(log, FILE_APPEND_DATA, FILE_SHARE_READ | FILE_SHARE_WRITE, + nullptr, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, nullptr); + } + if (handle != INVALID_HANDLE_VALUE) { + sFd = reinterpret_cast<intptr_t>(handle); + } +#else + if (fd == -1) { + fd = open(log, O_WRONLY | O_CREAT | O_APPEND, 0644); + } + if (fd > 0) { + sFd = fd; + } +#endif + } + + // Don't initialize if we weren't passed a valid MALLOC_LOG. + if (sFd == 0) { + return; + } + + sMutex.Init(); + static LogAllocBridge bridge; + sFuncs = *aTable; +#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC_BASE +#define MALLOC_DECL(name, ...) aTable->name = replace_##name; +#include "malloc_decls.h" + aTable->jemalloc_stats_internal = replace_jemalloc_stats; + if (!getenv("MALLOC_LOG_MINIMAL")) { + aTable->posix_memalign = replace_posix_memalign; + aTable->aligned_alloc = replace_aligned_alloc; + aTable->valloc = replace_valloc; + } + *aBridge = &bridge; + +#ifndef _WIN32 + /* When another thread has acquired a lock before forking, the child + * process will inherit the lock state but the thread, being nonexistent + * in the child process, will never release it, leading to a dead-lock + * whenever the child process gets the lock. We thus need to ensure no + * other thread is holding the lock before forking, by acquiring it + * ourselves, and releasing it after forking in the parent process and + * resetting it to its initial state in the child process. The latter is + * important because some implementations (notably macOS) prevent a lock from + * being unlocked by a different thread than the one which locked it in the + * first place. + * Windows doesn't have this problem since there is no fork(). + * The real allocator, however, might be doing the same thing (jemalloc + * does). But pthread_atfork `prepare` handlers (first argument) are + * processed in reverse order they were established. But replace_init + * runs before the real allocator has had any chance to initialize and + * call pthread_atfork itself. This leads to its prefork running before + * ours. This leads to a race condition that can lead to a deadlock like + * the following: + * - thread A forks. + * - libc calls real allocator's prefork, so thread A holds the real + * allocator lock. + * - thread B calls malloc, which calls our replace_malloc. + * - consequently, thread B holds our lock. + * - thread B then proceeds to call the real allocator's malloc, and + * waits for the real allocator's lock, which thread A holds. + * - libc calls our prefork, so thread A waits for our lock, which + * thread B holds. + * To avoid this race condition, the real allocator's prefork must be + * called after ours, which means it needs to be registered before ours. + * So trick the real allocator into initializing itself without more side + * effects by calling malloc with a size it can't possibly allocate. */ + sFuncs.malloc(-1); + pthread_atfork(prefork, postfork_parent, postfork_child); +#endif +} |