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Diffstat (limited to 'memory/build/mozjemalloc.cpp')
| -rw-r--r-- | memory/build/mozjemalloc.cpp | 5397 |
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diff --git a/memory/build/mozjemalloc.cpp b/memory/build/mozjemalloc.cpp new file mode 100644 index 0000000000..7a8211747f --- /dev/null +++ b/memory/build/mozjemalloc.cpp @@ -0,0 +1,5397 @@ +/* -*- 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/. */ + +// Portions of this file were originally under the following license: +// +// Copyright (C) 2006-2008 Jason Evans <jasone@FreeBSD.org>. +// All rights reserved. +// Copyright (C) 2007-2017 Mozilla Foundation. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions +// are met: +// 1. Redistributions of source code must retain the above copyright +// notice(s), this list of conditions and the following disclaimer as +// the first lines of this file unmodified other than the possible +// addition of one or more copyright notices. +// 2. Redistributions in binary form must reproduce the above copyright +// notice(s), this list of conditions and the following disclaimer in +// the documentation and/or other materials provided with the +// distribution. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY +// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE +// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR +// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, +// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE +// OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, +// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +// ***************************************************************************** +// +// This allocator implementation is designed to provide scalable performance +// for multi-threaded programs on multi-processor systems. The following +// features are included for this purpose: +// +// + Multiple arenas are used if there are multiple CPUs, which reduces lock +// contention and cache sloshing. +// +// + Cache line sharing between arenas is avoided for internal data +// structures. +// +// + Memory is managed in chunks and runs (chunks can be split into runs), +// rather than as individual pages. This provides a constant-time +// mechanism for associating allocations with particular arenas. +// +// Allocation requests are rounded up to the nearest size class, and no record +// of the original request size is maintained. Allocations are broken into +// categories according to size class. Assuming runtime defaults, the size +// classes in each category are as follows (for x86, x86_64 and Apple Silicon): +// +// |=========================================================| +// | Category | Subcategory | x86 | x86_64 | Mac ARM | +// |---------------------------+---------+---------+---------| +// | Word size | 32 bit | 64 bit | 64 bit | +// | Page size | 4 Kb | 4 Kb | 16 Kb | +// |=========================================================| +// | Small | Tiny | 4/-w | -w | - | +// | | | 8 | 8/-w | 8 | +// | |----------------+---------|---------|---------| +// | | Quantum-spaced | 16 | 16 | 16 | +// | | | 32 | 32 | 32 | +// | | | 48 | 48 | 48 | +// | | | ... | ... | ... | +// | | | 480 | 480 | 480 | +// | | | 496 | 496 | 496 | +// | |----------------+---------|---------|---------| +// | | Quantum-wide- | 512 | 512 | 512 | +// | | spaced | 768 | 768 | 768 | +// | | | ... | ... | ... | +// | | | 3584 | 3584 | 3584 | +// | | | 3840 | 3840 | 3840 | +// | |----------------+---------|---------|---------| +// | | Sub-page | - | - | 4096 | +// | | | - | - | 8 kB | +// |=========================================================| +// | Large | 4 kB | 4 kB | - | +// | | 8 kB | 8 kB | - | +// | | 12 kB | 12 kB | - | +// | | 16 kB | 16 kB | 16 kB | +// | | ... | ... | - | +// | | 32 kB | 32 kB | 32 kB | +// | | ... | ... | ... | +// | | 1008 kB | 1008 kB | 1008 kB | +// | | 1012 kB | 1012 kB | - | +// | | 1016 kB | 1016 kB | - | +// | | 1020 kB | 1020 kB | - | +// |=========================================================| +// | Huge | 1 MB | 1 MB | 1 MB | +// | | 2 MB | 2 MB | 2 MB | +// | | 3 MB | 3 MB | 3 MB | +// | | ... | ... | ... | +// |=========================================================| +// +// Legend: +// n: Size class exists for this platform. +// n/-w: This size class doesn't exist on Windows (see kMinTinyClass). +// -: This size class doesn't exist for this platform. +// ...: Size classes follow a pattern here. +// +// NOTE: Due to Mozilla bug 691003, we cannot reserve less than one word for an +// allocation on Linux or Mac. So on 32-bit *nix, the smallest bucket size is +// 4 bytes, and on 64-bit, the smallest bucket size is 8 bytes. +// +// A different mechanism is used for each category: +// +// Small : Each size class is segregated into its own set of runs. Each run +// maintains a bitmap of which regions are free/allocated. +// +// Large : Each allocation is backed by a dedicated run. Metadata are stored +// in the associated arena chunk header maps. +// +// Huge : Each allocation is backed by a dedicated contiguous set of chunks. +// Metadata are stored in a separate red-black tree. +// +// ***************************************************************************** + +#include "mozmemory_wrap.h" +#include "mozjemalloc.h" +#include "mozjemalloc_types.h" + +#include <cstring> +#include <cerrno> +#include <optional> +#include <type_traits> +#ifdef XP_WIN +# include <io.h> +# include <windows.h> +#else +# include <sys/mman.h> +# include <unistd.h> +#endif +#ifdef XP_DARWIN +# include <libkern/OSAtomic.h> +# include <mach/mach_init.h> +# include <mach/vm_map.h> +#endif + +#include "mozilla/Atomics.h" +#include "mozilla/Alignment.h" +#include "mozilla/ArrayUtils.h" +#include "mozilla/Assertions.h" +#include "mozilla/CheckedInt.h" +#include "mozilla/DoublyLinkedList.h" +#include "mozilla/HelperMacros.h" +#include "mozilla/Likely.h" +#include "mozilla/Literals.h" +#include "mozilla/MathAlgorithms.h" +#include "mozilla/RandomNum.h" +// Note: MozTaggedAnonymousMmap() could call an LD_PRELOADed mmap +// instead of the one defined here; use only MozTagAnonymousMemory(). +#include "mozilla/TaggedAnonymousMemory.h" +#include "mozilla/ThreadLocal.h" +#include "mozilla/UniquePtr.h" +#include "mozilla/Unused.h" +#include "mozilla/XorShift128PlusRNG.h" +#include "mozilla/fallible.h" +#include "rb.h" +#include "Mutex.h" +#include "PHC.h" +#include "Utils.h" + +#if defined(XP_WIN) +# include "mozmemory_utils.h" +#endif + +// For GetGeckoProcessType(), when it's used. +#if defined(XP_WIN) && !defined(JS_STANDALONE) +# include "mozilla/ProcessType.h" +#endif + +using namespace mozilla; + +// On Linux, we use madvise(MADV_DONTNEED) to release memory back to the +// operating system. If we release 1MB of live pages with MADV_DONTNEED, our +// RSS will decrease by 1MB (almost) immediately. +// +// On Mac, we use madvise(MADV_FREE). Unlike MADV_DONTNEED on Linux, MADV_FREE +// on Mac doesn't cause the OS to release the specified pages immediately; the +// OS keeps them in our process until the machine comes under memory pressure. +// +// It's therefore difficult to measure the process's RSS on Mac, since, in the +// absence of memory pressure, the contribution from the heap to RSS will not +// decrease due to our madvise calls. +// +// We therefore define MALLOC_DOUBLE_PURGE on Mac. This causes jemalloc to +// track which pages have been MADV_FREE'd. You can then call +// jemalloc_purge_freed_pages(), which will force the OS to release those +// MADV_FREE'd pages, making the process's RSS reflect its true memory usage. +// +// The jemalloc_purge_freed_pages definition in memory/build/mozmemory.h needs +// to be adjusted if MALLOC_DOUBLE_PURGE is ever enabled on Linux. + +#ifdef XP_DARWIN +# define MALLOC_DOUBLE_PURGE +#endif + +#ifdef XP_WIN +# define MALLOC_DECOMMIT +#endif + +// Define MALLOC_RUNTIME_CONFIG depending on MOZ_DEBUG. Overriding this as +// a build option allows us to build mozjemalloc/firefox without runtime asserts +// but with runtime configuration. Making some testing easier. + +#ifdef MOZ_DEBUG +# define MALLOC_RUNTIME_CONFIG +#endif + +// When MALLOC_STATIC_PAGESIZE is defined, the page size is fixed at +// compile-time for better performance, as opposed to determined at +// runtime. Some platforms can have different page sizes at runtime +// depending on kernel configuration, so they are opted out by default. +// Debug builds are opted out too, for test coverage. +#ifndef MALLOC_RUNTIME_CONFIG +# if !defined(__ia64__) && !defined(__sparc__) && !defined(__mips__) && \ + !defined(__aarch64__) && !defined(__powerpc__) && !defined(XP_MACOSX) && \ + !defined(__loongarch__) +# define MALLOC_STATIC_PAGESIZE 1 +# endif +#endif + +#ifdef XP_WIN +# define STDERR_FILENO 2 + +// Implement getenv without using malloc. +static char mozillaMallocOptionsBuf[64]; + +# define getenv xgetenv +static char* getenv(const char* name) { + if (GetEnvironmentVariableA(name, mozillaMallocOptionsBuf, + sizeof(mozillaMallocOptionsBuf)) > 0) { + return mozillaMallocOptionsBuf; + } + + return nullptr; +} +#endif + +#ifndef XP_WIN +// Newer Linux systems support MADV_FREE, but we're not supporting +// that properly. bug #1406304. +# if defined(XP_LINUX) && defined(MADV_FREE) +# undef MADV_FREE +# endif +# ifndef MADV_FREE +# define MADV_FREE MADV_DONTNEED +# endif +#endif + +// Some tools, such as /dev/dsp wrappers, LD_PRELOAD libraries that +// happen to override mmap() and call dlsym() from their overridden +// mmap(). The problem is that dlsym() calls malloc(), and this ends +// up in a dead lock in jemalloc. +// On these systems, we prefer to directly use the system call. +// We do that for Linux systems and kfreebsd with GNU userland. +// Note sanity checks are not done (alignment of offset, ...) because +// the uses of mmap are pretty limited, in jemalloc. +// +// On Alpha, glibc has a bug that prevents syscall() to work for system +// calls with 6 arguments. +#if (defined(XP_LINUX) && !defined(__alpha__)) || \ + (defined(__FreeBSD_kernel__) && defined(__GLIBC__)) +# include <sys/syscall.h> +# if defined(SYS_mmap) || defined(SYS_mmap2) +static inline void* _mmap(void* addr, size_t length, int prot, int flags, + int fd, off_t offset) { +// S390 only passes one argument to the mmap system call, which is a +// pointer to a structure containing the arguments. +# ifdef __s390__ + struct { + void* addr; + size_t length; + long prot; + long flags; + long fd; + off_t offset; + } args = {addr, length, prot, flags, fd, offset}; + return (void*)syscall(SYS_mmap, &args); +# else +# if defined(ANDROID) && defined(__aarch64__) && defined(SYS_mmap2) + // Android NDK defines SYS_mmap2 for AArch64 despite it not supporting mmap2. +# undef SYS_mmap2 +# endif +# ifdef SYS_mmap2 + return (void*)syscall(SYS_mmap2, addr, length, prot, flags, fd, offset >> 12); +# else + return (void*)syscall(SYS_mmap, addr, length, prot, flags, fd, offset); +# endif +# endif +} +# define mmap _mmap +# define munmap(a, l) syscall(SYS_munmap, a, l) +# endif +#endif + +// *************************************************************************** +// Structures for chunk headers for chunks used for non-huge allocations. + +struct arena_t; + +// Each element of the chunk map corresponds to one page within the chunk. +struct arena_chunk_map_t { + // Linkage for run trees. There are two disjoint uses: + // + // 1) arena_t's tree or available runs. + // 2) arena_run_t conceptually uses this linkage for in-use non-full + // runs, rather than directly embedding linkage. + RedBlackTreeNode<arena_chunk_map_t> link; + + // Run address (or size) and various flags are stored together. The bit + // layout looks like (assuming 32-bit system): + // + // ???????? ???????? ????---- -mckdzla + // + // ? : Unallocated: Run address for first/last pages, unset for internal + // pages. + // Small: Run address. + // Large: Run size for first page, unset for trailing pages. + // - : Unused. + // m : MADV_FREE/MADV_DONTNEED'ed? + // c : decommitted? + // k : key? + // d : dirty? + // z : zeroed? + // l : large? + // a : allocated? + // + // Following are example bit patterns for the three types of runs. + // + // r : run address + // s : run size + // x : don't care + // - : 0 + // [cdzla] : bit set + // + // Unallocated: + // ssssssss ssssssss ssss---- --c----- + // xxxxxxxx xxxxxxxx xxxx---- ----d--- + // ssssssss ssssssss ssss---- -----z-- + // + // Small: + // rrrrrrrr rrrrrrrr rrrr---- -------a + // rrrrrrrr rrrrrrrr rrrr---- -------a + // rrrrrrrr rrrrrrrr rrrr---- -------a + // + // Large: + // ssssssss ssssssss ssss---- ------la + // -------- -------- -------- ------la + // -------- -------- -------- ------la + size_t bits; + +// Note that CHUNK_MAP_DECOMMITTED's meaning varies depending on whether +// MALLOC_DECOMMIT and MALLOC_DOUBLE_PURGE are defined. +// +// If MALLOC_DECOMMIT is defined, a page which is CHUNK_MAP_DECOMMITTED must be +// re-committed with pages_commit() before it may be touched. If +// MALLOC_DECOMMIT is defined, MALLOC_DOUBLE_PURGE may not be defined. +// +// If neither MALLOC_DECOMMIT nor MALLOC_DOUBLE_PURGE is defined, pages which +// are madvised (with either MADV_DONTNEED or MADV_FREE) are marked with +// CHUNK_MAP_MADVISED. +// +// Otherwise, if MALLOC_DECOMMIT is not defined and MALLOC_DOUBLE_PURGE is +// defined, then a page which is madvised is marked as CHUNK_MAP_MADVISED. +// When it's finally freed with jemalloc_purge_freed_pages, the page is marked +// as CHUNK_MAP_DECOMMITTED. +#define CHUNK_MAP_MADVISED ((size_t)0x40U) +#define CHUNK_MAP_DECOMMITTED ((size_t)0x20U) +#define CHUNK_MAP_MADVISED_OR_DECOMMITTED \ + (CHUNK_MAP_MADVISED | CHUNK_MAP_DECOMMITTED) +#define CHUNK_MAP_KEY ((size_t)0x10U) +#define CHUNK_MAP_DIRTY ((size_t)0x08U) +#define CHUNK_MAP_ZEROED ((size_t)0x04U) +#define CHUNK_MAP_LARGE ((size_t)0x02U) +#define CHUNK_MAP_ALLOCATED ((size_t)0x01U) +}; + +// Arena chunk header. +struct arena_chunk_t { + // Arena that owns the chunk. + arena_t* arena; + + // Linkage for the arena's tree of dirty chunks. + RedBlackTreeNode<arena_chunk_t> link_dirty; + +#ifdef MALLOC_DOUBLE_PURGE + // If we're double-purging, we maintain a linked list of chunks which + // have pages which have been madvise(MADV_FREE)'d but not explicitly + // purged. + // + // We're currently lazy and don't remove a chunk from this list when + // all its madvised pages are recommitted. + DoublyLinkedListElement<arena_chunk_t> chunks_madvised_elem; +#endif + + // Number of dirty pages. + size_t ndirty; + + // Map of pages within chunk that keeps track of free/large/small. + arena_chunk_map_t map[1]; // Dynamically sized. +}; + +// *************************************************************************** +// Constants defining allocator size classes and behavior. + +// Maximum size of L1 cache line. This is used to avoid cache line aliasing, +// so over-estimates are okay (up to a point), but under-estimates will +// negatively affect performance. +static const size_t kCacheLineSize = 64; + +// Our size classes are inclusive ranges of memory sizes. By describing the +// minimums and how memory is allocated in each range the maximums can be +// calculated. + +// Smallest size class to support. On Windows the smallest allocation size +// must be 8 bytes on 32-bit, 16 bytes on 64-bit. On Linux and Mac, even +// malloc(1) must reserve a word's worth of memory (see Mozilla bug 691003). +#ifdef XP_WIN +static const size_t kMinTinyClass = sizeof(void*) * 2; +#else +static const size_t kMinTinyClass = sizeof(void*); +#endif + +// Maximum tiny size class. +static const size_t kMaxTinyClass = 8; + +// Smallest quantum-spaced size classes. It could actually also be labelled a +// tiny allocation, and is spaced as such from the largest tiny size class. +// Tiny classes being powers of 2, this is twice as large as the largest of +// them. +static const size_t kMinQuantumClass = kMaxTinyClass * 2; +static const size_t kMinQuantumWideClass = 512; +static const size_t kMinSubPageClass = 4_KiB; + +// Amount (quantum) separating quantum-spaced size classes. +static const size_t kQuantum = 16; +static const size_t kQuantumMask = kQuantum - 1; +static const size_t kQuantumWide = 256; +static const size_t kQuantumWideMask = kQuantumWide - 1; + +static const size_t kMaxQuantumClass = kMinQuantumWideClass - kQuantum; +static const size_t kMaxQuantumWideClass = kMinSubPageClass - kQuantumWide; + +// We can optimise some divisions to shifts if these are powers of two. +static_assert(mozilla::IsPowerOfTwo(kQuantum), + "kQuantum is not a power of two"); +static_assert(mozilla::IsPowerOfTwo(kQuantumWide), + "kQuantumWide is not a power of two"); + +static_assert(kMaxQuantumClass % kQuantum == 0, + "kMaxQuantumClass is not a multiple of kQuantum"); +static_assert(kMaxQuantumWideClass % kQuantumWide == 0, + "kMaxQuantumWideClass is not a multiple of kQuantumWide"); +static_assert(kQuantum < kQuantumWide, + "kQuantum must be smaller than kQuantumWide"); +static_assert(mozilla::IsPowerOfTwo(kMinSubPageClass), + "kMinSubPageClass is not a power of two"); + +// Number of (2^n)-spaced tiny classes. +static const size_t kNumTinyClasses = + LOG2(kMaxTinyClass) - LOG2(kMinTinyClass) + 1; + +// Number of quantum-spaced classes. We add kQuantum(Max) before subtracting to +// avoid underflow when a class is empty (Max<Min). +static const size_t kNumQuantumClasses = + (kMaxQuantumClass + kQuantum - kMinQuantumClass) / kQuantum; +static const size_t kNumQuantumWideClasses = + (kMaxQuantumWideClass + kQuantumWide - kMinQuantumWideClass) / kQuantumWide; + +// Size and alignment of memory chunks that are allocated by the OS's virtual +// memory system. +static const size_t kChunkSize = 1_MiB; +static const size_t kChunkSizeMask = kChunkSize - 1; + +#ifdef MALLOC_STATIC_PAGESIZE +// VM page size. It must divide the runtime CPU page size or the code +// will abort. +// Platform specific page size conditions copied from js/public/HeapAPI.h +# if defined(__powerpc64__) +static const size_t gPageSize = 64_KiB; +# elif defined(__loongarch64) +static const size_t gPageSize = 16_KiB; +# else +static const size_t gPageSize = 4_KiB; +# endif +static const size_t gRealPageSize = gPageSize; + +#else +// When MALLOC_OPTIONS contains one or several `P`s, the page size used +// across the allocator is multiplied by 2 for each `P`, but we also keep +// the real page size for code paths that need it. gPageSize is thus a +// power of two greater or equal to gRealPageSize. +static size_t gRealPageSize; +static size_t gPageSize; +#endif + +#ifdef MALLOC_STATIC_PAGESIZE +# define DECLARE_GLOBAL(type, name) +# define DEFINE_GLOBALS +# define END_GLOBALS +# define DEFINE_GLOBAL(type) static const type +# define GLOBAL_LOG2 LOG2 +# define GLOBAL_ASSERT_HELPER1(x) static_assert(x, #x) +# define GLOBAL_ASSERT_HELPER2(x, y) static_assert(x, y) +# define GLOBAL_ASSERT(...) \ + MACRO_CALL( \ + MOZ_PASTE_PREFIX_AND_ARG_COUNT(GLOBAL_ASSERT_HELPER, __VA_ARGS__), \ + (__VA_ARGS__)) +# define GLOBAL_CONSTEXPR constexpr +#else +# define DECLARE_GLOBAL(type, name) static type name; +# define DEFINE_GLOBALS static void DefineGlobals() { +# define END_GLOBALS } +# define DEFINE_GLOBAL(type) +# define GLOBAL_LOG2 FloorLog2 +# define GLOBAL_ASSERT MOZ_RELEASE_ASSERT +# define GLOBAL_CONSTEXPR +#endif + +DECLARE_GLOBAL(size_t, gMaxSubPageClass) +DECLARE_GLOBAL(uint8_t, gNumSubPageClasses) +DECLARE_GLOBAL(uint8_t, gPageSize2Pow) +DECLARE_GLOBAL(size_t, gPageSizeMask) +DECLARE_GLOBAL(size_t, gChunkNumPages) +DECLARE_GLOBAL(size_t, gChunkHeaderNumPages) +DECLARE_GLOBAL(size_t, gMaxLargeClass) + +DEFINE_GLOBALS + +// Largest sub-page size class, or zero if there are none +DEFINE_GLOBAL(size_t) +gMaxSubPageClass = gPageSize / 2 >= kMinSubPageClass ? gPageSize / 2 : 0; + +// Max size class for bins. +#define gMaxBinClass \ + (gMaxSubPageClass ? gMaxSubPageClass : kMaxQuantumWideClass) + +// Number of sub-page bins. +DEFINE_GLOBAL(uint8_t) +gNumSubPageClasses = []() GLOBAL_CONSTEXPR -> uint8_t { + if GLOBAL_CONSTEXPR (gMaxSubPageClass != 0) { + return FloorLog2(gMaxSubPageClass) - LOG2(kMinSubPageClass) + 1; + } + return 0; +}(); + +DEFINE_GLOBAL(uint8_t) gPageSize2Pow = GLOBAL_LOG2(gPageSize); +DEFINE_GLOBAL(size_t) gPageSizeMask = gPageSize - 1; + +// Number of pages in a chunk. +DEFINE_GLOBAL(size_t) gChunkNumPages = kChunkSize >> gPageSize2Pow; + +// Number of pages necessary for a chunk header plus a guard page. +DEFINE_GLOBAL(size_t) +gChunkHeaderNumPages = + 1 + (((sizeof(arena_chunk_t) + + sizeof(arena_chunk_map_t) * (gChunkNumPages - 1) + gPageSizeMask) & + ~gPageSizeMask) >> + gPageSize2Pow); + +// One chunk, minus the header, minus a guard page +DEFINE_GLOBAL(size_t) +gMaxLargeClass = + kChunkSize - gPageSize - (gChunkHeaderNumPages << gPageSize2Pow); + +// Various sanity checks that regard configuration. +GLOBAL_ASSERT(1ULL << gPageSize2Pow == gPageSize, + "Page size is not a power of two"); +GLOBAL_ASSERT(kQuantum >= sizeof(void*)); +GLOBAL_ASSERT(kQuantum <= kQuantumWide); +GLOBAL_ASSERT(!kNumQuantumWideClasses || + kQuantumWide <= (kMinSubPageClass - kMaxQuantumClass)); + +GLOBAL_ASSERT(kQuantumWide <= kMaxQuantumClass); + +GLOBAL_ASSERT(gMaxSubPageClass >= kMinSubPageClass || gMaxSubPageClass == 0); +GLOBAL_ASSERT(gMaxLargeClass >= gMaxSubPageClass); +GLOBAL_ASSERT(kChunkSize >= gPageSize); +GLOBAL_ASSERT(kQuantum * 4 <= kChunkSize); + +END_GLOBALS + +// Recycle at most 128 MiB of chunks. This means we retain at most +// 6.25% of the process address space on a 32-bit OS for later use. +static const size_t gRecycleLimit = 128_MiB; + +// The current amount of recycled bytes, updated atomically. +static Atomic<size_t, ReleaseAcquire> gRecycledSize; + +// Maximum number of dirty pages per arena. +#define DIRTY_MAX_DEFAULT (1U << 8) + +static size_t opt_dirty_max = DIRTY_MAX_DEFAULT; + +// Return the smallest chunk multiple that is >= s. +#define CHUNK_CEILING(s) (((s) + kChunkSizeMask) & ~kChunkSizeMask) + +// Return the smallest cacheline multiple that is >= s. +#define CACHELINE_CEILING(s) \ + (((s) + (kCacheLineSize - 1)) & ~(kCacheLineSize - 1)) + +// Return the smallest quantum multiple that is >= a. +#define QUANTUM_CEILING(a) (((a) + (kQuantumMask)) & ~(kQuantumMask)) +#define QUANTUM_WIDE_CEILING(a) \ + (((a) + (kQuantumWideMask)) & ~(kQuantumWideMask)) + +// Return the smallest sub page-size that is >= a. +#define SUBPAGE_CEILING(a) (RoundUpPow2(a)) + +// Return the smallest pagesize multiple that is >= s. +#define PAGE_CEILING(s) (((s) + gPageSizeMask) & ~gPageSizeMask) + +// Number of all the small-allocated classes +#define NUM_SMALL_CLASSES \ + (kNumTinyClasses + kNumQuantumClasses + kNumQuantumWideClasses + \ + gNumSubPageClasses) + +// *************************************************************************** +// MALLOC_DECOMMIT and MALLOC_DOUBLE_PURGE are mutually exclusive. +#if defined(MALLOC_DECOMMIT) && defined(MALLOC_DOUBLE_PURGE) +# error MALLOC_DECOMMIT and MALLOC_DOUBLE_PURGE are mutually exclusive. +#endif + +static void* base_alloc(size_t aSize); + +// Set to true once the allocator has been initialized. +#if defined(_MSC_VER) && !defined(__clang__) +// MSVC may create a static initializer for an Atomic<bool>, which may actually +// run after `malloc_init` has been called once, which triggers multiple +// initializations. +// We work around the problem by not using an Atomic<bool> at all. There is a +// theoretical problem with using `malloc_initialized` non-atomically, but +// practically, this is only true if `malloc_init` is never called before +// threads are created. +static bool malloc_initialized; +#else +static Atomic<bool, MemoryOrdering::ReleaseAcquire> malloc_initialized; +#endif + +static StaticMutex gInitLock MOZ_UNANNOTATED = {STATIC_MUTEX_INIT}; + +// *************************************************************************** +// Statistics data structures. + +struct arena_stats_t { + // Number of bytes currently mapped. + size_t mapped; + + // Current number of committed pages. + size_t committed; + + // Per-size-category statistics. + size_t allocated_small; + + size_t allocated_large; +}; + +// *************************************************************************** +// Extent data structures. + +enum ChunkType { + UNKNOWN_CHUNK, + ZEROED_CHUNK, // chunk only contains zeroes. + ARENA_CHUNK, // used to back arena runs created by arena_t::AllocRun. + HUGE_CHUNK, // used to back huge allocations (e.g. arena_t::MallocHuge). + RECYCLED_CHUNK, // chunk has been stored for future use by chunk_recycle. +}; + +// Tree of extents. +struct extent_node_t { + union { + // Linkage for the size/address-ordered tree for chunk recycling. + RedBlackTreeNode<extent_node_t> mLinkBySize; + // Arena id for huge allocations. It's meant to match mArena->mId, + // which only holds true when the arena hasn't been disposed of. + arena_id_t mArenaId; + }; + + // Linkage for the address-ordered tree. + RedBlackTreeNode<extent_node_t> mLinkByAddr; + + // Pointer to the extent that this tree node is responsible for. + void* mAddr; + + // Total region size. + size_t mSize; + + union { + // What type of chunk is there; used for chunk recycling. + ChunkType mChunkType; + + // A pointer to the associated arena, for huge allocations. + arena_t* mArena; + }; +}; + +struct ExtentTreeSzTrait { + static RedBlackTreeNode<extent_node_t>& GetTreeNode(extent_node_t* aThis) { + return aThis->mLinkBySize; + } + + static inline Order Compare(extent_node_t* aNode, extent_node_t* aOther) { + Order ret = CompareInt(aNode->mSize, aOther->mSize); + return (ret != Order::eEqual) ? ret + : CompareAddr(aNode->mAddr, aOther->mAddr); + } +}; + +struct ExtentTreeTrait { + static RedBlackTreeNode<extent_node_t>& GetTreeNode(extent_node_t* aThis) { + return aThis->mLinkByAddr; + } + + static inline Order Compare(extent_node_t* aNode, extent_node_t* aOther) { + return CompareAddr(aNode->mAddr, aOther->mAddr); + } +}; + +struct ExtentTreeBoundsTrait : public ExtentTreeTrait { + static inline Order Compare(extent_node_t* aKey, extent_node_t* aNode) { + uintptr_t key_addr = reinterpret_cast<uintptr_t>(aKey->mAddr); + uintptr_t node_addr = reinterpret_cast<uintptr_t>(aNode->mAddr); + size_t node_size = aNode->mSize; + + // Is aKey within aNode? + if (node_addr <= key_addr && key_addr < node_addr + node_size) { + return Order::eEqual; + } + + return CompareAddr(aKey->mAddr, aNode->mAddr); + } +}; + +// Describe size classes to which allocations are rounded up to. +// TODO: add large and huge types when the arena allocation code +// changes in a way that allows it to be beneficial. +class SizeClass { + public: + enum ClassType { + Tiny, + Quantum, + QuantumWide, + SubPage, + Large, + }; + + explicit inline SizeClass(size_t aSize) { + if (aSize <= kMaxTinyClass) { + mType = Tiny; + mSize = std::max(RoundUpPow2(aSize), kMinTinyClass); + } else if (aSize <= kMaxQuantumClass) { + mType = Quantum; + mSize = QUANTUM_CEILING(aSize); + } else if (aSize <= kMaxQuantumWideClass) { + mType = QuantumWide; + mSize = QUANTUM_WIDE_CEILING(aSize); + } else if (aSize <= gMaxSubPageClass) { + mType = SubPage; + mSize = SUBPAGE_CEILING(aSize); + } else if (aSize <= gMaxLargeClass) { + mType = Large; + mSize = PAGE_CEILING(aSize); + } else { + MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE("Invalid size"); + } + } + + SizeClass& operator=(const SizeClass& aOther) = default; + + bool operator==(const SizeClass& aOther) { return aOther.mSize == mSize; } + + size_t Size() { return mSize; } + + ClassType Type() { return mType; } + + SizeClass Next() { return SizeClass(mSize + 1); } + + private: + ClassType mType; + size_t mSize; +}; + +// Fast division +// +// During deallocation we want to divide by the size class. This class +// provides a routine and sets up a constant as follows. +// +// To divide by a number D that is not a power of two we multiply by (2^17 / +// D) and then right shift by 17 positions. +// +// X / D +// +// becomes +// +// (X * m) >> p +// +// Where m is calculated during the FastDivisor constructor similarly to: +// +// m = 2^p / D +// +template <typename T> +class FastDivisor { + private: + // The shift amount (p) is chosen to minimise the size of m while + // working for divisors up to 65536 in steps of 16. I arrived at 17 + // experimentally. I wanted a low number to minimise the range of m + // so it can fit in a uint16_t, 16 didn't work but 17 worked perfectly. + // + // We'd need to increase this if we allocated memory on smaller boundaries + // than 16. + static const unsigned p = 17; + + // We can fit the inverted divisor in 16 bits, but we template it here for + // convenience. + T m; + + public: + // Needed so mBins can be constructed. + FastDivisor() : m(0) {} + + FastDivisor(unsigned div, unsigned max) { + MOZ_ASSERT(div <= max); + + // divide_inv_shift is large enough. + MOZ_ASSERT((1U << p) >= div); + + // The calculation here for m is formula 26 from Section + // 10-9 "Unsigned Division by Divisors >= 1" in + // Henry S. Warren, Jr.'s Hacker's Delight, 2nd Ed. + unsigned m_ = ((1U << p) + div - 1 - (((1U << p) - 1) % div)) / div; + + // Make sure that max * m does not overflow. + MOZ_DIAGNOSTIC_ASSERT(max < UINT_MAX / m_); + + MOZ_ASSERT(m_ <= std::numeric_limits<T>::max()); + m = static_cast<T>(m_); + + // Initialisation made m non-zero. + MOZ_ASSERT(m); + + // Test that all the divisions in the range we expected would work. +#ifdef MOZ_DEBUG + for (unsigned num = 0; num < max; num += div) { + MOZ_ASSERT(num / div == divide(num)); + } +#endif + } + + // Note that this always occurs in uint32_t regardless of m's type. If m is + // a uint16_t it will be zero-extended before the multiplication. We also use + // uint32_t rather than something that could possibly be larger because it is + // most-likely the cheapest multiplication. + inline uint32_t divide(uint32_t num) const { + // Check that m was initialised. + MOZ_ASSERT(m); + return (num * m) >> p; + } +}; + +template <typename T> +unsigned inline operator/(unsigned num, FastDivisor<T> divisor) { + return divisor.divide(num); +} + +// *************************************************************************** +// Radix tree data structures. +// +// The number of bits passed to the template is the number of significant bits +// in an address to do a radix lookup with. +// +// An address is looked up by splitting it in kBitsPerLevel bit chunks, except +// the most significant bits, where the bit chunk is kBitsAtLevel1 which can be +// different if Bits is not a multiple of kBitsPerLevel. +// +// With e.g. sizeof(void*)=4, Bits=16 and kBitsPerLevel=8, an address is split +// like the following: +// 0x12345678 -> mRoot[0x12][0x34] +template <size_t Bits> +class AddressRadixTree { +// Size of each radix tree node (as a power of 2). +// This impacts tree depth. +#ifdef HAVE_64BIT_BUILD + static const size_t kNodeSize = kCacheLineSize; +#else + static const size_t kNodeSize = 16_KiB; +#endif + static const size_t kBitsPerLevel = LOG2(kNodeSize) - LOG2(sizeof(void*)); + static const size_t kBitsAtLevel1 = + (Bits % kBitsPerLevel) ? Bits % kBitsPerLevel : kBitsPerLevel; + static const size_t kHeight = (Bits + kBitsPerLevel - 1) / kBitsPerLevel; + static_assert(kBitsAtLevel1 + (kHeight - 1) * kBitsPerLevel == Bits, + "AddressRadixTree parameters don't work out"); + + Mutex mLock MOZ_UNANNOTATED; + void** mRoot; + + public: + bool Init(); + + inline void* Get(void* aAddr); + + // Returns whether the value was properly set. + inline bool Set(void* aAddr, void* aValue); + + inline bool Unset(void* aAddr) { return Set(aAddr, nullptr); } + + private: + inline void** GetSlot(void* aAddr, bool aCreate = false); +}; + +// *************************************************************************** +// Arena data structures. + +struct arena_bin_t; + +struct ArenaChunkMapLink { + static RedBlackTreeNode<arena_chunk_map_t>& GetTreeNode( + arena_chunk_map_t* aThis) { + return aThis->link; + } +}; + +struct ArenaRunTreeTrait : public ArenaChunkMapLink { + static inline Order Compare(arena_chunk_map_t* aNode, + arena_chunk_map_t* aOther) { + MOZ_ASSERT(aNode); + MOZ_ASSERT(aOther); + return CompareAddr(aNode, aOther); + } +}; + +struct ArenaAvailTreeTrait : public ArenaChunkMapLink { + static inline Order Compare(arena_chunk_map_t* aNode, + arena_chunk_map_t* aOther) { + size_t size1 = aNode->bits & ~gPageSizeMask; + size_t size2 = aOther->bits & ~gPageSizeMask; + Order ret = CompareInt(size1, size2); + return (ret != Order::eEqual) + ? ret + : CompareAddr((aNode->bits & CHUNK_MAP_KEY) ? nullptr : aNode, + aOther); + } +}; + +struct ArenaDirtyChunkTrait { + static RedBlackTreeNode<arena_chunk_t>& GetTreeNode(arena_chunk_t* aThis) { + return aThis->link_dirty; + } + + static inline Order Compare(arena_chunk_t* aNode, arena_chunk_t* aOther) { + MOZ_ASSERT(aNode); + MOZ_ASSERT(aOther); + return CompareAddr(aNode, aOther); + } +}; + +#ifdef MALLOC_DOUBLE_PURGE +namespace mozilla { + +template <> +struct GetDoublyLinkedListElement<arena_chunk_t> { + static DoublyLinkedListElement<arena_chunk_t>& Get(arena_chunk_t* aThis) { + return aThis->chunks_madvised_elem; + } +}; +} // namespace mozilla +#endif + +struct arena_run_t { +#if defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) + uint32_t mMagic; +# define ARENA_RUN_MAGIC 0x384adf93 + + // On 64-bit platforms, having the arena_bin_t pointer following + // the mMagic field means there's padding between both fields, making + // the run header larger than necessary. + // But when MOZ_DIAGNOSTIC_ASSERT_ENABLED is not set, starting the + // header with this field followed by the arena_bin_t pointer yields + // the same padding. We do want the mMagic field to appear first, so + // depending whether MOZ_DIAGNOSTIC_ASSERT_ENABLED is set or not, we + // move some field to avoid padding. + + // Number of free regions in run. + unsigned mNumFree; +#endif + + // Bin this run is associated with. + arena_bin_t* mBin; + + // Index of first element that might have a free region. + unsigned mRegionsMinElement; + +#if !defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) + // Number of free regions in run. + unsigned mNumFree; +#endif + + // Bitmask of in-use regions (0: in use, 1: free). + unsigned mRegionsMask[1]; // Dynamically sized. +}; + +struct arena_bin_t { + // Current run being used to service allocations of this bin's size + // class. + arena_run_t* mCurrentRun; + + // Tree of non-full runs. This tree is used when looking for an + // existing run when mCurrentRun is no longer usable. We choose the + // non-full run that is lowest in memory; this policy tends to keep + // objects packed well, and it can also help reduce the number of + // almost-empty chunks. + RedBlackTree<arena_chunk_map_t, ArenaRunTreeTrait> mNonFullRuns; + + // Bin's size class. + size_t mSizeClass; + + // Total number of regions in a run for this bin's size class. + uint32_t mRunNumRegions; + + // Number of elements in a run's mRegionsMask for this bin's size class. + uint32_t mRunNumRegionsMask; + + // Offset of first region in a run for this bin's size class. + uint32_t mRunFirstRegionOffset; + + // Current number of runs in this bin, full or otherwise. + uint32_t mNumRuns; + + // A constant for fast division by size class. This value is 16 bits wide so + // it is placed last. + FastDivisor<uint16_t> mSizeDivisor; + + // Total number of pages in a run for this bin's size class. + uint8_t mRunSizePages; + + // Amount of overhead runs are allowed to have. + static constexpr double kRunOverhead = 1.6_percent; + static constexpr double kRunRelaxedOverhead = 2.4_percent; + + // Initialize a bin for the given size class. + // The generated run sizes, for a page size of 4 KiB, are: + // size|run size|run size|run size|run + // class|size class|size class|size class|size + // 4 4 KiB 8 4 KiB 16 4 KiB 32 4 KiB + // 48 4 KiB 64 4 KiB 80 4 KiB 96 4 KiB + // 112 4 KiB 128 8 KiB 144 4 KiB 160 8 KiB + // 176 4 KiB 192 4 KiB 208 8 KiB 224 4 KiB + // 240 8 KiB 256 16 KiB 272 8 KiB 288 4 KiB + // 304 12 KiB 320 12 KiB 336 4 KiB 352 8 KiB + // 368 4 KiB 384 8 KiB 400 20 KiB 416 16 KiB + // 432 12 KiB 448 4 KiB 464 16 KiB 480 8 KiB + // 496 20 KiB 512 32 KiB 768 16 KiB 1024 64 KiB + // 1280 24 KiB 1536 32 KiB 1792 16 KiB 2048 128 KiB + // 2304 16 KiB 2560 48 KiB 2816 36 KiB 3072 64 KiB + // 3328 36 KiB 3584 32 KiB 3840 64 KiB + inline void Init(SizeClass aSizeClass); +}; + +// We try to keep the above structure aligned with common cache lines sizes, +// often that's 64 bytes on x86 and ARM, we don't make assumptions for other +// architectures. +#if defined(__x86_64__) || defined(__aarch64__) +// On 64bit platforms this structure is often 48 bytes +// long, which means every other array element will be properly aligned. +static_assert(sizeof(arena_bin_t) == 48); +#elif defined(__x86__) || defined(__arm__) +static_assert(sizeof(arena_bin_t) == 32); +#endif + +struct arena_t { +#if defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) + uint32_t mMagic; +# define ARENA_MAGIC 0x947d3d24 +#endif + + // Linkage for the tree of arenas by id. + RedBlackTreeNode<arena_t> mLink; + + // Arena id, that we keep away from the beginning of the struct so that + // free list pointers in TypedBaseAlloc<arena_t> don't overflow in it, + // and it keeps the value it had after the destructor. + arena_id_t mId; + + // All operations on this arena require that lock be locked. The MaybeMutex + // class well elude locking if the arena is accessed from a single thread + // only. + MaybeMutex mLock MOZ_UNANNOTATED; + + arena_stats_t mStats; + + private: + // Tree of dirty-page-containing chunks this arena manages. + RedBlackTree<arena_chunk_t, ArenaDirtyChunkTrait> mChunksDirty; + +#ifdef MALLOC_DOUBLE_PURGE + // Head of a linked list of MADV_FREE'd-page-containing chunks this + // arena manages. + DoublyLinkedList<arena_chunk_t> mChunksMAdvised; +#endif + + // In order to avoid rapid chunk allocation/deallocation when an arena + // oscillates right on the cusp of needing a new chunk, cache the most + // recently freed chunk. The spare is left in the arena's chunk trees + // until it is deleted. + // + // There is one spare chunk per arena, rather than one spare total, in + // order to avoid interactions between multiple threads that could make + // a single spare inadequate. + arena_chunk_t* mSpare; + + // A per-arena opt-in to randomize the offset of small allocations + bool mRandomizeSmallAllocations; + + // Whether this is a private arena. Multiple public arenas are just a + // performance optimization and not a safety feature. + // + // Since, for example, we don't want thread-local arenas to grow too much, we + // use the default arena for bigger allocations. We use this member to allow + // realloc() to switch out of our arena if needed (which is not allowed for + // private arenas for security). + bool mIsPrivate; + + // A pseudorandom number generator. Initially null, it gets initialized + // on first use to avoid recursive malloc initialization (e.g. on OSX + // arc4random allocates memory). + mozilla::non_crypto::XorShift128PlusRNG* mPRNG; + + public: + // Current count of pages within unused runs that are potentially + // dirty, and for which madvise(... MADV_FREE) has not been called. By + // tracking this, we can institute a limit on how much dirty unused + // memory is mapped for each arena. + size_t mNumDirty; + + // Maximum value allowed for mNumDirty. + size_t mMaxDirty; + + int32_t mMaxDirtyIncreaseOverride; + int32_t mMaxDirtyDecreaseOverride; + + private: + // Size/address-ordered tree of this arena's available runs. This tree + // is used for first-best-fit run allocation. + RedBlackTree<arena_chunk_map_t, ArenaAvailTreeTrait> mRunsAvail; + + public: + // mBins is used to store rings of free regions of the following sizes, + // assuming a 16-byte quantum, 4kB pagesize, and default MALLOC_OPTIONS. + // + // | mBins[i] | size | + // +----------+------+ + // | 0 | 2 | + // | 1 | 4 | + // | 2 | 8 | + // +----------+------+ + // | 3 | 16 | + // | 4 | 32 | + // | 5 | 48 | + // | 6 | 64 | + // | : : + // | : : + // | 33 | 496 | + // | 34 | 512 | + // +----------+------+ + // | 35 | 768 | + // | 36 | 1024 | + // | : : + // | : : + // | 46 | 3584 | + // | 47 | 3840 | + // +----------+------+ + arena_bin_t mBins[1]; // Dynamically sized. + + explicit arena_t(arena_params_t* aParams, bool aIsPrivate); + ~arena_t(); + + private: + void InitChunk(arena_chunk_t* aChunk); + + // This may return a chunk that should be destroyed with chunk_dealloc outside + // of the arena lock. It is not the same chunk as was passed in (since that + // chunk now becomes mSpare). + [[nodiscard]] arena_chunk_t* DeallocChunk(arena_chunk_t* aChunk); + + arena_run_t* AllocRun(size_t aSize, bool aLarge, bool aZero); + + arena_chunk_t* DallocRun(arena_run_t* aRun, bool aDirty); + + [[nodiscard]] bool SplitRun(arena_run_t* aRun, size_t aSize, bool aLarge, + bool aZero); + + void TrimRunHead(arena_chunk_t* aChunk, arena_run_t* aRun, size_t aOldSize, + size_t aNewSize); + + void TrimRunTail(arena_chunk_t* aChunk, arena_run_t* aRun, size_t aOldSize, + size_t aNewSize, bool dirty); + + arena_run_t* GetNonFullBinRun(arena_bin_t* aBin); + + inline uint8_t FindFreeBitInMask(uint32_t aMask, uint32_t& aRng); + + inline void* ArenaRunRegAlloc(arena_run_t* aRun, arena_bin_t* aBin); + + inline void* MallocSmall(size_t aSize, bool aZero); + + void* MallocLarge(size_t aSize, bool aZero); + + void* MallocHuge(size_t aSize, bool aZero); + + void* PallocLarge(size_t aAlignment, size_t aSize, size_t aAllocSize); + + void* PallocHuge(size_t aSize, size_t aAlignment, bool aZero); + + void RallocShrinkLarge(arena_chunk_t* aChunk, void* aPtr, size_t aSize, + size_t aOldSize); + + bool RallocGrowLarge(arena_chunk_t* aChunk, void* aPtr, size_t aSize, + size_t aOldSize); + + void* RallocSmallOrLarge(void* aPtr, size_t aSize, size_t aOldSize); + + void* RallocHuge(void* aPtr, size_t aSize, size_t aOldSize); + + public: + inline void* Malloc(size_t aSize, bool aZero); + + void* Palloc(size_t aAlignment, size_t aSize); + + // This may return a chunk that should be destroyed with chunk_dealloc outside + // of the arena lock. It is not the same chunk as was passed in (since that + // chunk now becomes mSpare). + [[nodiscard]] inline arena_chunk_t* DallocSmall(arena_chunk_t* aChunk, + void* aPtr, + arena_chunk_map_t* aMapElm); + + [[nodiscard]] arena_chunk_t* DallocLarge(arena_chunk_t* aChunk, void* aPtr); + + void* Ralloc(void* aPtr, size_t aSize, size_t aOldSize); + + size_t EffectiveMaxDirty(); + + // Passing one means purging all. + void Purge(size_t aMaxDirty); + + void HardPurge(); + + bool IsMainThreadOnly() const { return !mLock.LockIsEnabled(); } + + void* operator new(size_t aCount) = delete; + + void* operator new(size_t aCount, const fallible_t&) noexcept; + + void operator delete(void*); +}; + +struct ArenaTreeTrait { + static RedBlackTreeNode<arena_t>& GetTreeNode(arena_t* aThis) { + return aThis->mLink; + } + + static inline Order Compare(arena_t* aNode, arena_t* aOther) { + MOZ_ASSERT(aNode); + MOZ_ASSERT(aOther); + return CompareInt(aNode->mId, aOther->mId); + } +}; + +// Bookkeeping for all the arenas used by the allocator. +// Arenas are separated in two categories: +// - "private" arenas, used through the moz_arena_* API +// - all the other arenas: the default arena, and thread-local arenas, +// used by the standard API. +class ArenaCollection { + public: + bool Init() { + mArenas.Init(); + mPrivateArenas.Init(); + mMainThreadArenas.Init(); + arena_params_t params; + // The main arena allows more dirty pages than the default for other arenas. + params.mMaxDirty = opt_dirty_max; + mDefaultArena = + mLock.Init() ? CreateArena(/* aIsPrivate = */ false, ¶ms) : nullptr; + return bool(mDefaultArena); + } + + inline arena_t* GetById(arena_id_t aArenaId, bool aIsPrivate); + + arena_t* CreateArena(bool aIsPrivate, arena_params_t* aParams); + + void DisposeArena(arena_t* aArena) { + MutexAutoLock lock(mLock); + Tree& tree = + aArena->IsMainThreadOnly() ? mMainThreadArenas : mPrivateArenas; + + MOZ_RELEASE_ASSERT(tree.Search(aArena), "Arena not in tree"); + tree.Remove(aArena); + delete aArena; + } + + void SetDefaultMaxDirtyPageModifier(int32_t aModifier) { + mDefaultMaxDirtyPageModifier = aModifier; + } + int32_t DefaultMaxDirtyPageModifier() { return mDefaultMaxDirtyPageModifier; } + + using Tree = RedBlackTree<arena_t, ArenaTreeTrait>; + + struct Iterator : Tree::Iterator { + explicit Iterator(Tree* aTree, Tree* aSecondTree, + Tree* aThirdTree = nullptr) + : Tree::Iterator(aTree), + mSecondTree(aSecondTree), + mThirdTree(aThirdTree) {} + + Item<Iterator> begin() { + return Item<Iterator>(this, *Tree::Iterator::begin()); + } + + Item<Iterator> end() { return Item<Iterator>(this, nullptr); } + + arena_t* Next() { + arena_t* result = Tree::Iterator::Next(); + if (!result && mSecondTree) { + new (this) Iterator(mSecondTree, mThirdTree); + result = *Tree::Iterator::begin(); + } + return result; + } + + private: + Tree* mSecondTree; + Tree* mThirdTree; + }; + + Iterator iter() { + if (IsOnMainThreadWeak()) { + return Iterator(&mArenas, &mPrivateArenas, &mMainThreadArenas); + } + return Iterator(&mArenas, &mPrivateArenas); + } + + inline arena_t* GetDefault() { return mDefaultArena; } + + Mutex mLock MOZ_UNANNOTATED; + + // We're running on the main thread which is set by a call to SetMainThread(). + bool IsOnMainThread() const { + return mMainThreadId.isSome() && mMainThreadId.value() == GetThreadId(); + } + + // We're running on the main thread or SetMainThread() has never been called. + bool IsOnMainThreadWeak() const { + return mMainThreadId.isNothing() || IsOnMainThread(); + } + + // After a fork set the new thread ID in the child. + void PostForkFixMainThread() { + if (mMainThreadId.isSome()) { + // Only if the main thread has been defined. + mMainThreadId = Some(GetThreadId()); + } + } + + void SetMainThread() { + MutexAutoLock lock(mLock); + MOZ_ASSERT(mMainThreadId.isNothing()); + mMainThreadId = Some(GetThreadId()); + } + + private: + const static arena_id_t MAIN_THREAD_ARENA_BIT = 0x1; + + inline arena_t* GetByIdInternal(Tree& aTree, arena_id_t aArenaId); + + arena_id_t MakeRandArenaId(bool aIsMainThreadOnly) const; + static bool ArenaIdIsMainThreadOnly(arena_id_t aArenaId) { + return aArenaId & MAIN_THREAD_ARENA_BIT; + } + + arena_t* mDefaultArena; + arena_id_t mLastPublicArenaId; + + // Accessing mArenas and mPrivateArenas can only be done while holding mLock. + // Since mMainThreadArenas can only be used from the main thread, it can be + // accessed without a lock which is why it is a seperate tree. + Tree mArenas; + Tree mPrivateArenas; + Tree mMainThreadArenas; + Atomic<int32_t, MemoryOrdering::Relaxed> mDefaultMaxDirtyPageModifier; + Maybe<ThreadId> mMainThreadId; +}; + +static ArenaCollection gArenas; + +// ****** +// Chunks. +static AddressRadixTree<(sizeof(void*) << 3) - LOG2(kChunkSize)> gChunkRTree; + +// Protects chunk-related data structures. +static Mutex chunks_mtx; + +// Trees of chunks that were previously allocated (trees differ only in node +// ordering). These are used when allocating chunks, in an attempt to re-use +// address space. Depending on function, different tree orderings are needed, +// which is why there are two trees with the same contents. +static RedBlackTree<extent_node_t, ExtentTreeSzTrait> gChunksBySize + MOZ_GUARDED_BY(chunks_mtx); +static RedBlackTree<extent_node_t, ExtentTreeTrait> gChunksByAddress + MOZ_GUARDED_BY(chunks_mtx); + +// Protects huge allocation-related data structures. +static Mutex huge_mtx; + +// Tree of chunks that are stand-alone huge allocations. +static RedBlackTree<extent_node_t, ExtentTreeTrait> huge + MOZ_GUARDED_BY(huge_mtx); + +// Huge allocation statistics. +static size_t huge_allocated MOZ_GUARDED_BY(huge_mtx); +static size_t huge_mapped MOZ_GUARDED_BY(huge_mtx); + +// ************************** +// base (internal allocation). + +static Mutex base_mtx; + +// Current pages that are being used for internal memory allocations. These +// pages are carved up in cacheline-size quanta, so that there is no chance of +// false cache line sharing. +static void* base_pages MOZ_GUARDED_BY(base_mtx); +static void* base_next_addr MOZ_GUARDED_BY(base_mtx); +static void* base_next_decommitted MOZ_GUARDED_BY(base_mtx); +// Address immediately past base_pages. +static void* base_past_addr MOZ_GUARDED_BY(base_mtx); +static size_t base_mapped MOZ_GUARDED_BY(base_mtx); +static size_t base_committed MOZ_GUARDED_BY(base_mtx); + +// ****** +// Arenas. + +// The arena associated with the current thread (per +// jemalloc_thread_local_arena) On OSX, __thread/thread_local circles back +// calling malloc to allocate storage on first access on each thread, which +// leads to an infinite loop, but pthread-based TLS somehow doesn't have this +// problem. +#if !defined(XP_DARWIN) +static MOZ_THREAD_LOCAL(arena_t*) thread_arena; +#else +static detail::ThreadLocal<arena_t*, detail::ThreadLocalKeyStorage> + thread_arena; +#endif + +// ***************************** +// Runtime configuration options. + +#ifdef MALLOC_RUNTIME_CONFIG +# define MALLOC_RUNTIME_VAR static +#else +# define MALLOC_RUNTIME_VAR static const +#endif + +enum PoisonType { + NONE, + SOME, + ALL, +}; + +MALLOC_RUNTIME_VAR bool opt_junk = false; +MALLOC_RUNTIME_VAR bool opt_zero = false; + +#ifdef EARLY_BETA_OR_EARLIER +MALLOC_RUNTIME_VAR PoisonType opt_poison = ALL; +#else +MALLOC_RUNTIME_VAR PoisonType opt_poison = SOME; +#endif + +MALLOC_RUNTIME_VAR size_t opt_poison_size = kCacheLineSize * 4; + +static bool opt_randomize_small = true; + +// *************************************************************************** +// Begin forward declarations. + +static void* chunk_alloc(size_t aSize, size_t aAlignment, bool aBase); +static void chunk_dealloc(void* aChunk, size_t aSize, ChunkType aType); +#ifdef MOZ_DEBUG +static void chunk_assert_zero(void* aPtr, size_t aSize); +#endif +static void huge_dalloc(void* aPtr, arena_t* aArena); +static bool malloc_init_hard(); + +#ifndef XP_WIN +# ifdef XP_DARWIN +# define FORK_HOOK extern "C" +# else +# define FORK_HOOK static +# endif +FORK_HOOK void _malloc_prefork(void); +FORK_HOOK void _malloc_postfork_parent(void); +FORK_HOOK void _malloc_postfork_child(void); +#endif + +// End forward declarations. +// *************************************************************************** + +// FreeBSD's pthreads implementation calls malloc(3), so the malloc +// implementation has to take pains to avoid infinite recursion during +// initialization. +// Returns whether the allocator was successfully initialized. +static inline bool malloc_init() { + if (!malloc_initialized) { + return malloc_init_hard(); + } + return true; +} + +static void _malloc_message(const char* p) { +#if !defined(XP_WIN) +# define _write write +#endif + // Pretend to check _write() errors to suppress gcc warnings about + // warn_unused_result annotations in some versions of glibc headers. + if (_write(STDERR_FILENO, p, (unsigned int)strlen(p)) < 0) { + return; + } +} + +template <typename... Args> +static void _malloc_message(const char* p, Args... args) { + _malloc_message(p); + _malloc_message(args...); +} + +#ifdef ANDROID +// Android's pthread.h does not declare pthread_atfork() until SDK 21. +extern "C" MOZ_EXPORT int pthread_atfork(void (*)(void), void (*)(void), + void (*)(void)); +#endif + +// *************************************************************************** +// Begin Utility functions/macros. + +// Return the chunk address for allocation address a. +static inline arena_chunk_t* GetChunkForPtr(const void* aPtr) { + return (arena_chunk_t*)(uintptr_t(aPtr) & ~kChunkSizeMask); +} + +// Return the chunk offset of address a. +static inline size_t GetChunkOffsetForPtr(const void* aPtr) { + return (size_t)(uintptr_t(aPtr) & kChunkSizeMask); +} + +static inline const char* _getprogname(void) { return "<jemalloc>"; } + +static inline void MaybePoison(void* aPtr, size_t aSize) { + size_t size; + switch (opt_poison) { + case NONE: + return; + case SOME: + size = std::min(aSize, opt_poison_size); + break; + case ALL: + size = aSize; + break; + } + MOZ_ASSERT(size != 0 && size <= aSize); + memset(aPtr, kAllocPoison, size); +} + +// Fill the given range of memory with zeroes or junk depending on opt_junk and +// opt_zero. +static inline void ApplyZeroOrJunk(void* aPtr, size_t aSize) { + if (opt_junk) { + memset(aPtr, kAllocJunk, aSize); + } else if (opt_zero) { + memset(aPtr, 0, aSize); + } +} + +// On Windows, delay crashing on OOM. +#ifdef XP_WIN + +// Implementation of VirtualAlloc wrapper (bug 1716727). +namespace MozAllocRetries { + +// Maximum retry count on OOM. +constexpr size_t kMaxAttempts = 10; +// Minimum delay time between retries. (The actual delay time may be larger. See +// Microsoft's documentation for ::Sleep() for details.) +constexpr size_t kDelayMs = 50; + +using StallSpecs = ::mozilla::StallSpecs; + +static constexpr StallSpecs maxStall = {.maxAttempts = kMaxAttempts, + .delayMs = kDelayMs}; + +static inline StallSpecs GetStallSpecs() { +# if defined(JS_STANDALONE) + // GetGeckoProcessType() isn't available in this configuration. (SpiderMonkey + // on Windows mostly skips this in favor of directly calling ::VirtualAlloc(), + // though, so it's probably not going to matter whether we stall here or not.) + return maxStall; +# else + switch (GetGeckoProcessType()) { + // For the main process, stall for the maximum permissible time period. (The + // main process is the most important one to keep alive.) + case GeckoProcessType::GeckoProcessType_Default: + return maxStall; + + // For all other process types, stall for at most half as long. + default: + return {.maxAttempts = maxStall.maxAttempts / 2, + .delayMs = maxStall.delayMs}; + } +# endif +} + +// Drop-in wrapper around VirtualAlloc. When out of memory, may attempt to stall +// and retry rather than returning immediately, in hopes that the page file is +// about to be expanded by Windows. +// +// Ref: +// https://docs.microsoft.com/en-us/troubleshoot/windows-client/performance/slow-page-file-growth-memory-allocation-errors +[[nodiscard]] void* MozVirtualAlloc(LPVOID lpAddress, SIZE_T dwSize, + DWORD flAllocationType, DWORD flProtect) { + DWORD const lastError = ::GetLastError(); + + constexpr auto IsOOMError = [] { + switch (::GetLastError()) { + // This is the usual error result from VirtualAlloc for OOM. + case ERROR_COMMITMENT_LIMIT: + // Although rare, this has also been observed in low-memory situations. + // (Presumably this means Windows can't allocate enough kernel-side space + // for its own internal representation of the process's virtual address + // space.) + case ERROR_NOT_ENOUGH_MEMORY: + return true; + } + return false; + }; + + { + void* ptr = ::VirtualAlloc(lpAddress, dwSize, flAllocationType, flProtect); + if (MOZ_LIKELY(ptr)) return ptr; + + // We can't do anything for errors other than OOM... + if (!IsOOMError()) return nullptr; + // ... or if this wasn't a request to commit memory in the first place. + // (This function has no strategy for resolving MEM_RESERVE failures.) + if (!(flAllocationType & MEM_COMMIT)) return nullptr; + } + + // Retry as many times as desired (possibly zero). + const StallSpecs stallSpecs = GetStallSpecs(); + + const auto ret = + stallSpecs.StallAndRetry(&::Sleep, [&]() -> std::optional<void*> { + void* ptr = + ::VirtualAlloc(lpAddress, dwSize, flAllocationType, flProtect); + + if (ptr) { + // The OOM status has been handled, and should not be reported to + // telemetry. + if (IsOOMError()) { + ::SetLastError(lastError); + } + return ptr; + } + + // Failure for some reason other than OOM. + if (!IsOOMError()) { + return nullptr; + } + + return std::nullopt; + }); + + return ret.value_or(nullptr); +} +} // namespace MozAllocRetries + +using MozAllocRetries::MozVirtualAlloc; + +namespace mozilla { +MOZ_JEMALLOC_API StallSpecs GetAllocatorStallSpecs() { + return ::MozAllocRetries::GetStallSpecs(); +} +} // namespace mozilla + +#endif // XP_WIN + +// *************************************************************************** + +static inline void pages_decommit(void* aAddr, size_t aSize) { +#ifdef XP_WIN + // The region starting at addr may have been allocated in multiple calls + // to VirtualAlloc and recycled, so decommitting the entire region in one + // go may not be valid. However, since we allocate at least a chunk at a + // time, we may touch any region in chunksized increments. + size_t pages_size = std::min(aSize, kChunkSize - GetChunkOffsetForPtr(aAddr)); + while (aSize > 0) { + // This will cause Access Violation on read and write and thus act as a + // guard page or region as well. + if (!VirtualFree(aAddr, pages_size, MEM_DECOMMIT)) { + MOZ_CRASH(); + } + aAddr = (void*)((uintptr_t)aAddr + pages_size); + aSize -= pages_size; + pages_size = std::min(aSize, kChunkSize); + } +#else + if (mmap(aAddr, aSize, PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, + 0) == MAP_FAILED) { + // We'd like to report the OOM for our tooling, but we can't allocate + // memory at this point, so avoid the use of printf. + const char out_of_mappings[] = + "[unhandlable oom] Failed to mmap, likely no more mappings " + "available " __FILE__ " : " MOZ_STRINGIFY(__LINE__); + if (errno == ENOMEM) { +# ifndef ANDROID + fputs(out_of_mappings, stderr); + fflush(stderr); +# endif + MOZ_CRASH_ANNOTATE(out_of_mappings); + } + MOZ_REALLY_CRASH(__LINE__); + } + MozTagAnonymousMemory(aAddr, aSize, "jemalloc-decommitted"); +#endif +} + +// Commit pages. Returns whether pages were committed. +[[nodiscard]] static inline bool pages_commit(void* aAddr, size_t aSize) { +#ifdef XP_WIN + // The region starting at addr may have been allocated in multiple calls + // to VirtualAlloc and recycled, so committing the entire region in one + // go may not be valid. However, since we allocate at least a chunk at a + // time, we may touch any region in chunksized increments. + size_t pages_size = std::min(aSize, kChunkSize - GetChunkOffsetForPtr(aAddr)); + while (aSize > 0) { + if (!MozVirtualAlloc(aAddr, pages_size, MEM_COMMIT, PAGE_READWRITE)) { + return false; + } + aAddr = (void*)((uintptr_t)aAddr + pages_size); + aSize -= pages_size; + pages_size = std::min(aSize, kChunkSize); + } +#else + if (mmap(aAddr, aSize, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0) == MAP_FAILED) { + return false; + } + MozTagAnonymousMemory(aAddr, aSize, "jemalloc"); +#endif + return true; +} + +static bool base_pages_alloc(size_t minsize) MOZ_REQUIRES(base_mtx) { + size_t csize; + size_t pminsize; + + MOZ_ASSERT(minsize != 0); + csize = CHUNK_CEILING(minsize); + base_pages = chunk_alloc(csize, kChunkSize, true); + if (!base_pages) { + return true; + } + base_next_addr = base_pages; + base_past_addr = (void*)((uintptr_t)base_pages + csize); + // Leave enough pages for minsize committed, since otherwise they would + // have to be immediately recommitted. + pminsize = PAGE_CEILING(minsize); + base_next_decommitted = (void*)((uintptr_t)base_pages + pminsize); + if (pminsize < csize) { + pages_decommit(base_next_decommitted, csize - pminsize); + } + base_mapped += csize; + base_committed += pminsize; + + return false; +} + +static void* base_alloc(size_t aSize) { + void* ret; + size_t csize; + + // Round size up to nearest multiple of the cacheline size. + csize = CACHELINE_CEILING(aSize); + + MutexAutoLock lock(base_mtx); + // Make sure there's enough space for the allocation. + if ((uintptr_t)base_next_addr + csize > (uintptr_t)base_past_addr) { + if (base_pages_alloc(csize)) { + return nullptr; + } + } + // Allocate. + ret = base_next_addr; + base_next_addr = (void*)((uintptr_t)base_next_addr + csize); + // Make sure enough pages are committed for the new allocation. + if ((uintptr_t)base_next_addr > (uintptr_t)base_next_decommitted) { + void* pbase_next_addr = (void*)(PAGE_CEILING((uintptr_t)base_next_addr)); + + if (!pages_commit( + base_next_decommitted, + (uintptr_t)pbase_next_addr - (uintptr_t)base_next_decommitted)) { + return nullptr; + } + + base_committed += + (uintptr_t)pbase_next_addr - (uintptr_t)base_next_decommitted; + base_next_decommitted = pbase_next_addr; + } + + return ret; +} + +static void* base_calloc(size_t aNumber, size_t aSize) { + void* ret = base_alloc(aNumber * aSize); + if (ret) { + memset(ret, 0, aNumber * aSize); + } + return ret; +} + +// A specialization of the base allocator with a free list. +template <typename T> +struct TypedBaseAlloc { + static T* sFirstFree; + + static size_t size_of() { return sizeof(T); } + + static T* alloc() { + T* ret; + + base_mtx.Lock(); + if (sFirstFree) { + ret = sFirstFree; + sFirstFree = *(T**)ret; + base_mtx.Unlock(); + } else { + base_mtx.Unlock(); + ret = (T*)base_alloc(size_of()); + } + + return ret; + } + + static void dealloc(T* aNode) { + MutexAutoLock lock(base_mtx); + *(T**)aNode = sFirstFree; + sFirstFree = aNode; + } +}; + +using ExtentAlloc = TypedBaseAlloc<extent_node_t>; + +template <> +extent_node_t* ExtentAlloc::sFirstFree = nullptr; + +template <> +arena_t* TypedBaseAlloc<arena_t>::sFirstFree = nullptr; + +template <> +size_t TypedBaseAlloc<arena_t>::size_of() { + // Allocate enough space for trailing bins. + return sizeof(arena_t) + (sizeof(arena_bin_t) * (NUM_SMALL_CLASSES - 1)); +} + +template <typename T> +struct BaseAllocFreePolicy { + void operator()(T* aPtr) { TypedBaseAlloc<T>::dealloc(aPtr); } +}; + +using UniqueBaseNode = + UniquePtr<extent_node_t, BaseAllocFreePolicy<extent_node_t>>; + +// End Utility functions/macros. +// *************************************************************************** +// Begin chunk management functions. + +#ifdef XP_WIN + +static void* pages_map(void* aAddr, size_t aSize) { + void* ret = nullptr; + ret = MozVirtualAlloc(aAddr, aSize, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE); + return ret; +} + +static void pages_unmap(void* aAddr, size_t aSize) { + if (VirtualFree(aAddr, 0, MEM_RELEASE) == 0) { + _malloc_message(_getprogname(), ": (malloc) Error in VirtualFree()\n"); + } +} +#else + +static void pages_unmap(void* aAddr, size_t aSize) { + if (munmap(aAddr, aSize) == -1) { + char buf[64]; + + if (strerror_r(errno, buf, sizeof(buf)) == 0) { + _malloc_message(_getprogname(), ": (malloc) Error in munmap(): ", buf, + "\n"); + } + } +} + +static void* pages_map(void* aAddr, size_t aSize) { + void* ret; +# if defined(__ia64__) || \ + (defined(__sparc__) && defined(__arch64__) && defined(__linux__)) + // The JS engine assumes that all allocated pointers have their high 17 bits + // clear, which ia64's mmap doesn't support directly. However, we can emulate + // it by passing mmap an "addr" parameter with those bits clear. The mmap will + // return that address, or the nearest available memory above that address, + // providing a near-guarantee that those bits are clear. If they are not, we + // return nullptr below to indicate out-of-memory. + // + // The addr is chosen as 0x0000070000000000, which still allows about 120TB of + // virtual address space. + // + // See Bug 589735 for more information. + bool check_placement = true; + if (!aAddr) { + aAddr = (void*)0x0000070000000000; + check_placement = false; + } +# endif + +# if defined(__sparc__) && defined(__arch64__) && defined(__linux__) + const uintptr_t start = 0x0000070000000000ULL; + const uintptr_t end = 0x0000800000000000ULL; + + // Copied from js/src/gc/Memory.cpp and adapted for this source + uintptr_t hint; + void* region = MAP_FAILED; + for (hint = start; region == MAP_FAILED && hint + aSize <= end; + hint += kChunkSize) { + region = mmap((void*)hint, aSize, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANON, -1, 0); + if (region != MAP_FAILED) { + if (((size_t)region + (aSize - 1)) & 0xffff800000000000) { + if (munmap(region, aSize)) { + MOZ_ASSERT(errno == ENOMEM); + } + region = MAP_FAILED; + } + } + } + ret = region; +# else + // We don't use MAP_FIXED here, because it can cause the *replacement* + // of existing mappings, and we only want to create new mappings. + ret = + mmap(aAddr, aSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); + MOZ_ASSERT(ret); +# endif + if (ret == MAP_FAILED) { + ret = nullptr; + } +# if defined(__ia64__) || \ + (defined(__sparc__) && defined(__arch64__) && defined(__linux__)) + // If the allocated memory doesn't have its upper 17 bits clear, consider it + // as out of memory. + else if ((long long)ret & 0xffff800000000000) { + munmap(ret, aSize); + ret = nullptr; + } + // If the caller requested a specific memory location, verify that's what mmap + // returned. + else if (check_placement && ret != aAddr) { +# else + else if (aAddr && ret != aAddr) { +# endif + // We succeeded in mapping memory, but not in the right place. + pages_unmap(ret, aSize); + ret = nullptr; + } + if (ret) { + MozTagAnonymousMemory(ret, aSize, "jemalloc"); + } + +# if defined(__ia64__) || \ + (defined(__sparc__) && defined(__arch64__) && defined(__linux__)) + MOZ_ASSERT(!ret || (!check_placement && ret) || + (check_placement && ret == aAddr)); +# else + MOZ_ASSERT(!ret || (!aAddr && ret != aAddr) || (aAddr && ret == aAddr)); +# endif + return ret; +} +#endif + +#ifdef XP_DARWIN +# define VM_COPY_MIN kChunkSize +static inline void pages_copy(void* dest, const void* src, size_t n) { + MOZ_ASSERT((void*)((uintptr_t)dest & ~gPageSizeMask) == dest); + MOZ_ASSERT(n >= VM_COPY_MIN); + MOZ_ASSERT((void*)((uintptr_t)src & ~gPageSizeMask) == src); + + kern_return_t r = vm_copy(mach_task_self(), (vm_address_t)src, (vm_size_t)n, + (vm_address_t)dest); + if (r != KERN_SUCCESS) { + MOZ_CRASH("vm_copy() failed"); + } +} + +#endif + +template <size_t Bits> +bool AddressRadixTree<Bits>::Init() { + mLock.Init(); + mRoot = (void**)base_calloc(1 << kBitsAtLevel1, sizeof(void*)); + return mRoot; +} + +template <size_t Bits> +void** AddressRadixTree<Bits>::GetSlot(void* aKey, bool aCreate) { + uintptr_t key = reinterpret_cast<uintptr_t>(aKey); + uintptr_t subkey; + unsigned i, lshift, height, bits; + void** node; + void** child; + + for (i = lshift = 0, height = kHeight, node = mRoot; i < height - 1; + i++, lshift += bits, node = child) { + bits = i ? kBitsPerLevel : kBitsAtLevel1; + subkey = (key << lshift) >> ((sizeof(void*) << 3) - bits); + child = (void**)node[subkey]; + if (!child && aCreate) { + child = (void**)base_calloc(1 << kBitsPerLevel, sizeof(void*)); + if (child) { + node[subkey] = child; + } + } + if (!child) { + return nullptr; + } + } + + // node is a leaf, so it contains values rather than node + // pointers. + bits = i ? kBitsPerLevel : kBitsAtLevel1; + subkey = (key << lshift) >> ((sizeof(void*) << 3) - bits); + return &node[subkey]; +} + +template <size_t Bits> +void* AddressRadixTree<Bits>::Get(void* aKey) { + void* ret = nullptr; + + void** slot = GetSlot(aKey); + + if (slot) { + ret = *slot; + } +#ifdef MOZ_DEBUG + MutexAutoLock lock(mLock); + + // Suppose that it were possible for a jemalloc-allocated chunk to be + // munmap()ped, followed by a different allocator in another thread re-using + // overlapping virtual memory, all without invalidating the cached rtree + // value. The result would be a false positive (the rtree would claim that + // jemalloc owns memory that it had actually discarded). I don't think this + // scenario is possible, but the following assertion is a prudent sanity + // check. + if (!slot) { + // In case a slot has been created in the meantime. + slot = GetSlot(aKey); + } + if (slot) { + // The MutexAutoLock above should act as a memory barrier, forcing + // the compiler to emit a new read instruction for *slot. + MOZ_ASSERT(ret == *slot); + } else { + MOZ_ASSERT(ret == nullptr); + } +#endif + return ret; +} + +template <size_t Bits> +bool AddressRadixTree<Bits>::Set(void* aKey, void* aValue) { + MutexAutoLock lock(mLock); + void** slot = GetSlot(aKey, /* aCreate = */ true); + if (slot) { + *slot = aValue; + } + return slot; +} + +// pages_trim, chunk_alloc_mmap_slow and chunk_alloc_mmap were cherry-picked +// from upstream jemalloc 3.4.1 to fix Mozilla bug 956501. + +// Return the offset between a and the nearest aligned address at or below a. +#define ALIGNMENT_ADDR2OFFSET(a, alignment) \ + ((size_t)((uintptr_t)(a) & ((alignment)-1))) + +// Return the smallest alignment multiple that is >= s. +#define ALIGNMENT_CEILING(s, alignment) \ + (((s) + ((alignment)-1)) & (~((alignment)-1))) + +static void* pages_trim(void* addr, size_t alloc_size, size_t leadsize, + size_t size) { + void* ret = (void*)((uintptr_t)addr + leadsize); + + MOZ_ASSERT(alloc_size >= leadsize + size); +#ifdef XP_WIN + { + void* new_addr; + + pages_unmap(addr, alloc_size); + new_addr = pages_map(ret, size); + if (new_addr == ret) { + return ret; + } + if (new_addr) { + pages_unmap(new_addr, size); + } + return nullptr; + } +#else + { + size_t trailsize = alloc_size - leadsize - size; + + if (leadsize != 0) { + pages_unmap(addr, leadsize); + } + if (trailsize != 0) { + pages_unmap((void*)((uintptr_t)ret + size), trailsize); + } + return ret; + } +#endif +} + +static void* chunk_alloc_mmap_slow(size_t size, size_t alignment) { + void *ret, *pages; + size_t alloc_size, leadsize; + + alloc_size = size + alignment - gRealPageSize; + // Beware size_t wrap-around. + if (alloc_size < size) { + return nullptr; + } + do { + pages = pages_map(nullptr, alloc_size); + if (!pages) { + return nullptr; + } + leadsize = + ALIGNMENT_CEILING((uintptr_t)pages, alignment) - (uintptr_t)pages; + ret = pages_trim(pages, alloc_size, leadsize, size); + } while (!ret); + + MOZ_ASSERT(ret); + return ret; +} + +static void* chunk_alloc_mmap(size_t size, size_t alignment) { + void* ret; + size_t offset; + + // Ideally, there would be a way to specify alignment to mmap() (like + // NetBSD has), but in the absence of such a feature, we have to work + // hard to efficiently create aligned mappings. The reliable, but + // slow method is to create a mapping that is over-sized, then trim the + // excess. However, that always results in one or two calls to + // pages_unmap(). + // + // Optimistically try mapping precisely the right amount before falling + // back to the slow method, with the expectation that the optimistic + // approach works most of the time. + ret = pages_map(nullptr, size); + if (!ret) { + return nullptr; + } + offset = ALIGNMENT_ADDR2OFFSET(ret, alignment); + if (offset != 0) { + pages_unmap(ret, size); + return chunk_alloc_mmap_slow(size, alignment); + } + + MOZ_ASSERT(ret); + return ret; +} + +// Purge and release the pages in the chunk of length `length` at `addr` to +// the OS. +// Returns whether the pages are guaranteed to be full of zeroes when the +// function returns. +// The force_zero argument explicitly requests that the memory is guaranteed +// to be full of zeroes when the function returns. +static bool pages_purge(void* addr, size_t length, bool force_zero) { + pages_decommit(addr, length); + return true; +} + +static void* chunk_recycle(size_t aSize, size_t aAlignment) { + extent_node_t key; + + size_t alloc_size = aSize + aAlignment - kChunkSize; + // Beware size_t wrap-around. + if (alloc_size < aSize) { + return nullptr; + } + key.mAddr = nullptr; + key.mSize = alloc_size; + chunks_mtx.Lock(); + extent_node_t* node = gChunksBySize.SearchOrNext(&key); + if (!node) { + chunks_mtx.Unlock(); + return nullptr; + } + size_t leadsize = ALIGNMENT_CEILING((uintptr_t)node->mAddr, aAlignment) - + (uintptr_t)node->mAddr; + MOZ_ASSERT(node->mSize >= leadsize + aSize); + size_t trailsize = node->mSize - leadsize - aSize; + void* ret = (void*)((uintptr_t)node->mAddr + leadsize); + + // All recycled chunks are zeroed (because they're purged) before being + // recycled. + MOZ_ASSERT(node->mChunkType == ZEROED_CHUNK); + + // Remove node from the tree. + gChunksBySize.Remove(node); + gChunksByAddress.Remove(node); + if (leadsize != 0) { + // Insert the leading space as a smaller chunk. + node->mSize = leadsize; + gChunksBySize.Insert(node); + gChunksByAddress.Insert(node); + node = nullptr; + } + if (trailsize != 0) { + // Insert the trailing space as a smaller chunk. + if (!node) { + // An additional node is required, but + // TypedBaseAlloc::alloc() can cause a new base chunk to be + // allocated. Drop chunks_mtx in order to avoid + // deadlock, and if node allocation fails, deallocate + // the result before returning an error. + chunks_mtx.Unlock(); + node = ExtentAlloc::alloc(); + if (!node) { + chunk_dealloc(ret, aSize, ZEROED_CHUNK); + return nullptr; + } + chunks_mtx.Lock(); + } + node->mAddr = (void*)((uintptr_t)(ret) + aSize); + node->mSize = trailsize; + node->mChunkType = ZEROED_CHUNK; + gChunksBySize.Insert(node); + gChunksByAddress.Insert(node); + node = nullptr; + } + + gRecycledSize -= aSize; + + chunks_mtx.Unlock(); + + if (node) { + ExtentAlloc::dealloc(node); + } + if (!pages_commit(ret, aSize)) { + return nullptr; + } + + return ret; +} + +#ifdef XP_WIN +// On Windows, calls to VirtualAlloc and VirtualFree must be matched, making it +// awkward to recycle allocations of varying sizes. Therefore we only allow +// recycling when the size equals the chunksize, unless deallocation is entirely +// disabled. +# define CAN_RECYCLE(size) ((size) == kChunkSize) +#else +# define CAN_RECYCLE(size) true +#endif + +// Allocates `size` bytes of system memory aligned for `alignment`. +// `base` indicates whether the memory will be used for the base allocator +// (e.g. base_alloc). +// `zeroed` is an outvalue that returns whether the allocated memory is +// guaranteed to be full of zeroes. It can be omitted when the caller doesn't +// care about the result. +static void* chunk_alloc(size_t aSize, size_t aAlignment, bool aBase) { + void* ret = nullptr; + + MOZ_ASSERT(aSize != 0); + MOZ_ASSERT((aSize & kChunkSizeMask) == 0); + MOZ_ASSERT(aAlignment != 0); + MOZ_ASSERT((aAlignment & kChunkSizeMask) == 0); + + // Base allocations can't be fulfilled by recycling because of + // possible deadlock or infinite recursion. + if (CAN_RECYCLE(aSize) && !aBase) { + ret = chunk_recycle(aSize, aAlignment); + } + if (!ret) { + ret = chunk_alloc_mmap(aSize, aAlignment); + } + if (ret && !aBase) { + if (!gChunkRTree.Set(ret, ret)) { + chunk_dealloc(ret, aSize, UNKNOWN_CHUNK); + return nullptr; + } + } + + MOZ_ASSERT(GetChunkOffsetForPtr(ret) == 0); + return ret; +} + +#ifdef MOZ_DEBUG +static void chunk_assert_zero(void* aPtr, size_t aSize) { + size_t i; + size_t* p = (size_t*)(uintptr_t)aPtr; + + for (i = 0; i < aSize / sizeof(size_t); i++) { + MOZ_ASSERT(p[i] == 0); + } +} +#endif + +static void chunk_record(void* aChunk, size_t aSize, ChunkType aType) { + extent_node_t key; + + if (aType != ZEROED_CHUNK) { + if (pages_purge(aChunk, aSize, aType == HUGE_CHUNK)) { + aType = ZEROED_CHUNK; + } + } + + // Allocate a node before acquiring chunks_mtx even though it might not + // be needed, because TypedBaseAlloc::alloc() may cause a new base chunk to + // be allocated, which could cause deadlock if chunks_mtx were already + // held. + UniqueBaseNode xnode(ExtentAlloc::alloc()); + // Use xprev to implement conditional deferred deallocation of prev. + UniqueBaseNode xprev; + + // RAII deallocates xnode and xprev defined above after unlocking + // in order to avoid potential dead-locks + MutexAutoLock lock(chunks_mtx); + key.mAddr = (void*)((uintptr_t)aChunk + aSize); + extent_node_t* node = gChunksByAddress.SearchOrNext(&key); + // Try to coalesce forward. + if (node && node->mAddr == key.mAddr) { + // Coalesce chunk with the following address range. This does + // not change the position within gChunksByAddress, so only + // remove/insert from/into gChunksBySize. + gChunksBySize.Remove(node); + node->mAddr = aChunk; + node->mSize += aSize; + if (node->mChunkType != aType) { + node->mChunkType = RECYCLED_CHUNK; + } + gChunksBySize.Insert(node); + } else { + // Coalescing forward failed, so insert a new node. + if (!xnode) { + // TypedBaseAlloc::alloc() failed, which is an exceedingly + // unlikely failure. Leak chunk; its pages have + // already been purged, so this is only a virtual + // memory leak. + return; + } + node = xnode.release(); + node->mAddr = aChunk; + node->mSize = aSize; + node->mChunkType = aType; + gChunksByAddress.Insert(node); + gChunksBySize.Insert(node); + } + + // Try to coalesce backward. + extent_node_t* prev = gChunksByAddress.Prev(node); + if (prev && (void*)((uintptr_t)prev->mAddr + prev->mSize) == aChunk) { + // Coalesce chunk with the previous address range. This does + // not change the position within gChunksByAddress, so only + // remove/insert node from/into gChunksBySize. + gChunksBySize.Remove(prev); + gChunksByAddress.Remove(prev); + + gChunksBySize.Remove(node); + node->mAddr = prev->mAddr; + node->mSize += prev->mSize; + if (node->mChunkType != prev->mChunkType) { + node->mChunkType = RECYCLED_CHUNK; + } + gChunksBySize.Insert(node); + + xprev.reset(prev); + } + + gRecycledSize += aSize; +} + +static void chunk_dealloc(void* aChunk, size_t aSize, ChunkType aType) { + MOZ_ASSERT(aChunk); + MOZ_ASSERT(GetChunkOffsetForPtr(aChunk) == 0); + MOZ_ASSERT(aSize != 0); + MOZ_ASSERT((aSize & kChunkSizeMask) == 0); + + gChunkRTree.Unset(aChunk); + + if (CAN_RECYCLE(aSize)) { + size_t recycled_so_far = gRecycledSize; + // In case some race condition put us above the limit. + if (recycled_so_far < gRecycleLimit) { + size_t recycle_remaining = gRecycleLimit - recycled_so_far; + size_t to_recycle; + if (aSize > recycle_remaining) { + to_recycle = recycle_remaining; + // Drop pages that would overflow the recycle limit + pages_trim(aChunk, aSize, 0, to_recycle); + } else { + to_recycle = aSize; + } + chunk_record(aChunk, to_recycle, aType); + return; + } + } + + pages_unmap(aChunk, aSize); +} + +#undef CAN_RECYCLE + +// End chunk management functions. +// *************************************************************************** +// Begin arena. + +static inline arena_t* thread_local_arena(bool enabled) { + arena_t* arena; + + if (enabled) { + // The arena will essentially be leaked if this function is + // called with `false`, but it doesn't matter at the moment. + // because in practice nothing actually calls this function + // with `false`, except maybe at shutdown. + arena = + gArenas.CreateArena(/* aIsPrivate = */ false, /* aParams = */ nullptr); + } else { + arena = gArenas.GetDefault(); + } + thread_arena.set(arena); + return arena; +} + +inline void MozJemalloc::jemalloc_thread_local_arena(bool aEnabled) { + if (malloc_init()) { + thread_local_arena(aEnabled); + } +} + +// Choose an arena based on a per-thread value. +static inline arena_t* choose_arena(size_t size) { + arena_t* ret = nullptr; + + // We can only use TLS if this is a PIC library, since for the static + // library version, libc's malloc is used by TLS allocation, which + // introduces a bootstrapping issue. + + if (size > kMaxQuantumClass) { + // Force the default arena for larger allocations. + ret = gArenas.GetDefault(); + } else { + // Check TLS to see if our thread has requested a pinned arena. + ret = thread_arena.get(); + // If ret is non-null, it must not be in the first page. + MOZ_DIAGNOSTIC_ASSERT_IF(ret, (size_t)ret >= gPageSize); + if (!ret) { + // Nothing in TLS. Pin this thread to the default arena. + ret = thread_local_arena(false); + } + } + + MOZ_DIAGNOSTIC_ASSERT(ret); + return ret; +} + +inline uint8_t arena_t::FindFreeBitInMask(uint32_t aMask, uint32_t& aRng) { + if (mPRNG != nullptr) { + if (aRng == UINT_MAX) { + aRng = mPRNG->next() % 32; + } + uint8_t bitIndex; + // RotateRight asserts when provided bad input. + aMask = aRng ? RotateRight(aMask, aRng) + : aMask; // Rotate the mask a random number of slots + bitIndex = CountTrailingZeroes32(aMask); + return (bitIndex + aRng) % 32; + } + return CountTrailingZeroes32(aMask); +} + +inline void* arena_t::ArenaRunRegAlloc(arena_run_t* aRun, arena_bin_t* aBin) { + void* ret; + unsigned i, mask, bit, regind; + uint32_t rndPos = UINT_MAX; + + MOZ_DIAGNOSTIC_ASSERT(aRun->mMagic == ARENA_RUN_MAGIC); + MOZ_ASSERT(aRun->mRegionsMinElement < aBin->mRunNumRegionsMask); + + // Move the first check outside the loop, so that aRun->mRegionsMinElement can + // be updated unconditionally, without the possibility of updating it + // multiple times. + i = aRun->mRegionsMinElement; + mask = aRun->mRegionsMask[i]; + if (mask != 0) { + bit = FindFreeBitInMask(mask, rndPos); + + regind = ((i << (LOG2(sizeof(int)) + 3)) + bit); + MOZ_ASSERT(regind < aBin->mRunNumRegions); + ret = (void*)(((uintptr_t)aRun) + aBin->mRunFirstRegionOffset + + (aBin->mSizeClass * regind)); + + // Clear bit. + mask ^= (1U << bit); + aRun->mRegionsMask[i] = mask; + + return ret; + } + + for (i++; i < aBin->mRunNumRegionsMask; i++) { + mask = aRun->mRegionsMask[i]; + if (mask != 0) { + bit = FindFreeBitInMask(mask, rndPos); + + regind = ((i << (LOG2(sizeof(int)) + 3)) + bit); + MOZ_ASSERT(regind < aBin->mRunNumRegions); + ret = (void*)(((uintptr_t)aRun) + aBin->mRunFirstRegionOffset + + (aBin->mSizeClass * regind)); + + // Clear bit. + mask ^= (1U << bit); + aRun->mRegionsMask[i] = mask; + + // Make a note that nothing before this element + // contains a free region. + aRun->mRegionsMinElement = i; // Low payoff: + (mask == 0); + + return ret; + } + } + // Not reached. + MOZ_DIAGNOSTIC_ASSERT(0); + return nullptr; +} + +static inline void arena_run_reg_dalloc(arena_run_t* run, arena_bin_t* bin, + void* ptr, size_t size) { + uint32_t diff, regind; + unsigned elm, bit; + + MOZ_DIAGNOSTIC_ASSERT(run->mMagic == ARENA_RUN_MAGIC); + + // Avoid doing division with a variable divisor if possible. Using + // actual division here can reduce allocator throughput by over 20%! + diff = + (uint32_t)((uintptr_t)ptr - (uintptr_t)run - bin->mRunFirstRegionOffset); + + MOZ_ASSERT(diff <= + (static_cast<unsigned>(bin->mRunSizePages) << gPageSize2Pow)); + regind = diff / bin->mSizeDivisor; + + MOZ_DIAGNOSTIC_ASSERT(diff == regind * size); + MOZ_DIAGNOSTIC_ASSERT(regind < bin->mRunNumRegions); + + elm = regind >> (LOG2(sizeof(int)) + 3); + if (elm < run->mRegionsMinElement) { + run->mRegionsMinElement = elm; + } + bit = regind - (elm << (LOG2(sizeof(int)) + 3)); + MOZ_RELEASE_ASSERT((run->mRegionsMask[elm] & (1U << bit)) == 0, + "Double-free?"); + run->mRegionsMask[elm] |= (1U << bit); +} + +bool arena_t::SplitRun(arena_run_t* aRun, size_t aSize, bool aLarge, + bool aZero) { + arena_chunk_t* chunk; + size_t old_ndirty, run_ind, total_pages, need_pages, rem_pages, i; + + chunk = GetChunkForPtr(aRun); + old_ndirty = chunk->ndirty; + run_ind = (unsigned)((uintptr_t(aRun) - uintptr_t(chunk)) >> gPageSize2Pow); + total_pages = (chunk->map[run_ind].bits & ~gPageSizeMask) >> gPageSize2Pow; + need_pages = (aSize >> gPageSize2Pow); + MOZ_ASSERT(need_pages > 0); + MOZ_ASSERT(need_pages <= total_pages); + rem_pages = total_pages - need_pages; + + for (i = 0; i < need_pages; i++) { + // Commit decommitted pages if necessary. If a decommitted + // page is encountered, commit all needed adjacent decommitted + // pages in one operation, in order to reduce system call + // overhead. + if (chunk->map[run_ind + i].bits & CHUNK_MAP_MADVISED_OR_DECOMMITTED) { + size_t j; + + // Advance i+j to just past the index of the last page + // to commit. Clear CHUNK_MAP_DECOMMITTED and + // CHUNK_MAP_MADVISED along the way. + for (j = 0; i + j < need_pages && (chunk->map[run_ind + i + j].bits & + CHUNK_MAP_MADVISED_OR_DECOMMITTED); + j++) { + // DECOMMITTED and MADVISED are mutually exclusive. + MOZ_ASSERT(!(chunk->map[run_ind + i + j].bits & CHUNK_MAP_DECOMMITTED && + chunk->map[run_ind + i + j].bits & CHUNK_MAP_MADVISED)); + + chunk->map[run_ind + i + j].bits &= ~CHUNK_MAP_MADVISED_OR_DECOMMITTED; + } + +#ifdef MALLOC_DECOMMIT + bool committed = pages_commit( + (void*)(uintptr_t(chunk) + ((run_ind + i) << gPageSize2Pow)), + j << gPageSize2Pow); + // pages_commit zeroes pages, so mark them as such if it succeeded. + // That's checked further below to avoid manually zeroing the pages. + for (size_t k = 0; k < j; k++) { + chunk->map[run_ind + i + k].bits |= + committed ? CHUNK_MAP_ZEROED : CHUNK_MAP_DECOMMITTED; + } + if (!committed) { + return false; + } +#endif + + mStats.committed += j; + } + } + + mRunsAvail.Remove(&chunk->map[run_ind]); + + // Keep track of trailing unused pages for later use. + if (rem_pages > 0) { + chunk->map[run_ind + need_pages].bits = + (rem_pages << gPageSize2Pow) | + (chunk->map[run_ind + need_pages].bits & gPageSizeMask); + chunk->map[run_ind + total_pages - 1].bits = + (rem_pages << gPageSize2Pow) | + (chunk->map[run_ind + total_pages - 1].bits & gPageSizeMask); + mRunsAvail.Insert(&chunk->map[run_ind + need_pages]); + } + + for (i = 0; i < need_pages; i++) { + // Zero if necessary. + if (aZero) { + if ((chunk->map[run_ind + i].bits & CHUNK_MAP_ZEROED) == 0) { + memset((void*)(uintptr_t(chunk) + ((run_ind + i) << gPageSize2Pow)), 0, + gPageSize); + // CHUNK_MAP_ZEROED is cleared below. + } + } + + // Update dirty page accounting. + if (chunk->map[run_ind + i].bits & CHUNK_MAP_DIRTY) { + chunk->ndirty--; + mNumDirty--; + // CHUNK_MAP_DIRTY is cleared below. + } + + // Initialize the chunk map. + if (aLarge) { + chunk->map[run_ind + i].bits = CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + } else { + chunk->map[run_ind + i].bits = size_t(aRun) | CHUNK_MAP_ALLOCATED; + } + } + + // Set the run size only in the first element for large runs. This is + // primarily a debugging aid, since the lack of size info for trailing + // pages only matters if the application tries to operate on an + // interior pointer. + if (aLarge) { + chunk->map[run_ind].bits |= aSize; + } + + if (chunk->ndirty == 0 && old_ndirty > 0) { + mChunksDirty.Remove(chunk); + } + return true; +} + +void arena_t::InitChunk(arena_chunk_t* aChunk) { + size_t i; + // WARNING: The following relies on !aZeroed meaning "used to be an arena + // chunk". + // When the chunk we're initializating as an arena chunk is zeroed, we + // mark all runs are decommitted and zeroed. + // When it is not, which we can assume means it's a recycled arena chunk, + // all it can contain is an arena chunk header (which we're overwriting), + // and zeroed or poisoned memory (because a recycled arena chunk will + // have been emptied before being recycled). In that case, we can get + // away with reusing the chunk as-is, marking all runs as madvised. + + size_t flags = CHUNK_MAP_DECOMMITTED | CHUNK_MAP_ZEROED; + + mStats.mapped += kChunkSize; + + aChunk->arena = this; + + // Claim that no pages are in use, since the header is merely overhead. + aChunk->ndirty = 0; + + // Initialize the map to contain one maximal free untouched run. + arena_run_t* run = (arena_run_t*)(uintptr_t(aChunk) + + (gChunkHeaderNumPages << gPageSize2Pow)); + + // Clear the bits for the real header pages. + for (i = 0; i < gChunkHeaderNumPages - 1; i++) { + aChunk->map[i].bits = 0; + } + // Mark the leading guard page (last header page) as decommitted. + aChunk->map[i++].bits = CHUNK_MAP_DECOMMITTED; + + // Mark the area usable for runs as available, note size at start and end + aChunk->map[i++].bits = gMaxLargeClass | flags; + for (; i < gChunkNumPages - 2; i++) { + aChunk->map[i].bits = flags; + } + aChunk->map[gChunkNumPages - 2].bits = gMaxLargeClass | flags; + + // Mark the trailing guard page as decommitted. + aChunk->map[gChunkNumPages - 1].bits = CHUNK_MAP_DECOMMITTED; + +#ifdef MALLOC_DECOMMIT + // Start out decommitted, in order to force a closer correspondence + // between dirty pages and committed untouched pages. This includes + // leading and trailing guard pages. + pages_decommit((void*)(uintptr_t(run) - gPageSize), + gMaxLargeClass + 2 * gPageSize); +#else + // Decommit the last header page (=leading page) as a guard. + pages_decommit((void*)(uintptr_t(run) - gPageSize), gPageSize); + // Decommit the last page as a guard. + pages_decommit((void*)(uintptr_t(aChunk) + kChunkSize - gPageSize), + gPageSize); +#endif + + mStats.committed += gChunkHeaderNumPages - 1; + + // Insert the run into the tree of available runs. + mRunsAvail.Insert(&aChunk->map[gChunkHeaderNumPages]); + +#ifdef MALLOC_DOUBLE_PURGE + new (&aChunk->chunks_madvised_elem) DoublyLinkedListElement<arena_chunk_t>(); +#endif +} + +arena_chunk_t* arena_t::DeallocChunk(arena_chunk_t* aChunk) { + if (mSpare) { + if (mSpare->ndirty > 0) { + aChunk->arena->mChunksDirty.Remove(mSpare); + mNumDirty -= mSpare->ndirty; + mStats.committed -= mSpare->ndirty; + } + +#ifdef MALLOC_DOUBLE_PURGE + if (mChunksMAdvised.ElementProbablyInList(mSpare)) { + mChunksMAdvised.remove(mSpare); + } +#endif + + mStats.mapped -= kChunkSize; + mStats.committed -= gChunkHeaderNumPages - 1; + } + + // Remove run from the tree of available runs, so that the arena does not use + // it. Dirty page flushing only uses the tree of dirty chunks, so leaving this + // chunk in the chunks_* trees is sufficient for that purpose. + mRunsAvail.Remove(&aChunk->map[gChunkHeaderNumPages]); + + arena_chunk_t* chunk_dealloc = mSpare; + mSpare = aChunk; + return chunk_dealloc; +} + +arena_run_t* arena_t::AllocRun(size_t aSize, bool aLarge, bool aZero) { + arena_run_t* run; + arena_chunk_map_t* mapelm; + arena_chunk_map_t key; + + MOZ_ASSERT(aSize <= gMaxLargeClass); + MOZ_ASSERT((aSize & gPageSizeMask) == 0); + + // Search the arena's chunks for the lowest best fit. + key.bits = aSize | CHUNK_MAP_KEY; + mapelm = mRunsAvail.SearchOrNext(&key); + if (mapelm) { + arena_chunk_t* chunk = GetChunkForPtr(mapelm); + size_t pageind = + (uintptr_t(mapelm) - uintptr_t(chunk->map)) / sizeof(arena_chunk_map_t); + + run = (arena_run_t*)(uintptr_t(chunk) + (pageind << gPageSize2Pow)); + } else if (mSpare) { + // Use the spare. + arena_chunk_t* chunk = mSpare; + mSpare = nullptr; + run = (arena_run_t*)(uintptr_t(chunk) + + (gChunkHeaderNumPages << gPageSize2Pow)); + // Insert the run into the tree of available runs. + mRunsAvail.Insert(&chunk->map[gChunkHeaderNumPages]); + } else { + // No usable runs. Create a new chunk from which to allocate + // the run. + arena_chunk_t* chunk = + (arena_chunk_t*)chunk_alloc(kChunkSize, kChunkSize, false); + if (!chunk) { + return nullptr; + } + + InitChunk(chunk); + run = (arena_run_t*)(uintptr_t(chunk) + + (gChunkHeaderNumPages << gPageSize2Pow)); + } + // Update page map. + return SplitRun(run, aSize, aLarge, aZero) ? run : nullptr; +} + +size_t arena_t::EffectiveMaxDirty() { + int32_t modifier = gArenas.DefaultMaxDirtyPageModifier(); + if (modifier) { + int32_t arenaOverride = + modifier > 0 ? mMaxDirtyIncreaseOverride : mMaxDirtyDecreaseOverride; + if (arenaOverride) { + modifier = arenaOverride; + } + } + + return modifier >= 0 ? mMaxDirty << modifier : mMaxDirty >> -modifier; +} + +void arena_t::Purge(size_t aMaxDirty) { + arena_chunk_t* chunk; + size_t i, npages; + +#ifdef MOZ_DEBUG + size_t ndirty = 0; + for (auto chunk : mChunksDirty.iter()) { + ndirty += chunk->ndirty; + } + MOZ_ASSERT(ndirty == mNumDirty); +#endif + MOZ_DIAGNOSTIC_ASSERT(aMaxDirty == 1 || (mNumDirty > aMaxDirty)); + + // Iterate downward through chunks until enough dirty memory has been + // purged. Terminate as soon as possible in order to minimize the + // number of system calls, even if a chunk has only been partially + // purged. + while (mNumDirty > (aMaxDirty >> 1)) { +#ifdef MALLOC_DOUBLE_PURGE + bool madvised = false; +#endif + chunk = mChunksDirty.Last(); + MOZ_DIAGNOSTIC_ASSERT(chunk); + // Last page is DECOMMITTED as a guard page. + MOZ_ASSERT((chunk->map[gChunkNumPages - 1].bits & CHUNK_MAP_DECOMMITTED) != + 0); + for (i = gChunkNumPages - 2; chunk->ndirty > 0; i--) { + MOZ_DIAGNOSTIC_ASSERT(i >= gChunkHeaderNumPages); + + if (chunk->map[i].bits & CHUNK_MAP_DIRTY) { +#ifdef MALLOC_DECOMMIT + const size_t free_operation = CHUNK_MAP_DECOMMITTED; +#else + const size_t free_operation = CHUNK_MAP_MADVISED; +#endif + MOZ_ASSERT((chunk->map[i].bits & CHUNK_MAP_MADVISED_OR_DECOMMITTED) == + 0); + chunk->map[i].bits ^= free_operation | CHUNK_MAP_DIRTY; + // Find adjacent dirty run(s). + for (npages = 1; i > gChunkHeaderNumPages && + (chunk->map[i - 1].bits & CHUNK_MAP_DIRTY); + npages++) { + i--; + MOZ_ASSERT((chunk->map[i].bits & CHUNK_MAP_MADVISED_OR_DECOMMITTED) == + 0); + chunk->map[i].bits ^= free_operation | CHUNK_MAP_DIRTY; + } + chunk->ndirty -= npages; + mNumDirty -= npages; + +#ifdef MALLOC_DECOMMIT + pages_decommit((void*)(uintptr_t(chunk) + (i << gPageSize2Pow)), + (npages << gPageSize2Pow)); +#else +# ifdef XP_SOLARIS + posix_madvise((void*)(uintptr_t(chunk) + (i << gPageSize2Pow)), + (npages << gPageSize2Pow), MADV_FREE); +# else + madvise((void*)(uintptr_t(chunk) + (i << gPageSize2Pow)), + (npages << gPageSize2Pow), MADV_FREE); +# endif +# ifdef MALLOC_DOUBLE_PURGE + madvised = true; +# endif +#endif + mStats.committed -= npages; + + if (mNumDirty <= (aMaxDirty >> 1)) { + break; + } + } + } + + if (chunk->ndirty == 0) { + mChunksDirty.Remove(chunk); + } +#ifdef MALLOC_DOUBLE_PURGE + if (madvised) { + // The chunk might already be in the list, but this + // makes sure it's at the front. + if (mChunksMAdvised.ElementProbablyInList(chunk)) { + mChunksMAdvised.remove(chunk); + } + mChunksMAdvised.pushFront(chunk); + } +#endif + } +} + +arena_chunk_t* arena_t::DallocRun(arena_run_t* aRun, bool aDirty) { + arena_chunk_t* chunk; + size_t size, run_ind, run_pages; + + chunk = GetChunkForPtr(aRun); + run_ind = (size_t)((uintptr_t(aRun) - uintptr_t(chunk)) >> gPageSize2Pow); + MOZ_DIAGNOSTIC_ASSERT(run_ind >= gChunkHeaderNumPages); + MOZ_RELEASE_ASSERT(run_ind < gChunkNumPages - 1); + if ((chunk->map[run_ind].bits & CHUNK_MAP_LARGE) != 0) { + size = chunk->map[run_ind].bits & ~gPageSizeMask; + run_pages = (size >> gPageSize2Pow); + } else { + run_pages = aRun->mBin->mRunSizePages; + size = run_pages << gPageSize2Pow; + } + + // Mark pages as unallocated in the chunk map. + if (aDirty) { + size_t i; + + for (i = 0; i < run_pages; i++) { + MOZ_DIAGNOSTIC_ASSERT((chunk->map[run_ind + i].bits & CHUNK_MAP_DIRTY) == + 0); + chunk->map[run_ind + i].bits = CHUNK_MAP_DIRTY; + } + + if (chunk->ndirty == 0) { + mChunksDirty.Insert(chunk); + } + chunk->ndirty += run_pages; + mNumDirty += run_pages; + } else { + size_t i; + + for (i = 0; i < run_pages; i++) { + chunk->map[run_ind + i].bits &= ~(CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED); + } + } + chunk->map[run_ind].bits = size | (chunk->map[run_ind].bits & gPageSizeMask); + chunk->map[run_ind + run_pages - 1].bits = + size | (chunk->map[run_ind + run_pages - 1].bits & gPageSizeMask); + + // Try to coalesce forward. + if (run_ind + run_pages < gChunkNumPages - 1 && + (chunk->map[run_ind + run_pages].bits & CHUNK_MAP_ALLOCATED) == 0) { + size_t nrun_size = chunk->map[run_ind + run_pages].bits & ~gPageSizeMask; + + // Remove successor from tree of available runs; the coalesced run is + // inserted later. + mRunsAvail.Remove(&chunk->map[run_ind + run_pages]); + + size += nrun_size; + run_pages = size >> gPageSize2Pow; + + MOZ_DIAGNOSTIC_ASSERT((chunk->map[run_ind + run_pages - 1].bits & + ~gPageSizeMask) == nrun_size); + chunk->map[run_ind].bits = + size | (chunk->map[run_ind].bits & gPageSizeMask); + chunk->map[run_ind + run_pages - 1].bits = + size | (chunk->map[run_ind + run_pages - 1].bits & gPageSizeMask); + } + + // Try to coalesce backward. + if (run_ind > gChunkHeaderNumPages && + (chunk->map[run_ind - 1].bits & CHUNK_MAP_ALLOCATED) == 0) { + size_t prun_size = chunk->map[run_ind - 1].bits & ~gPageSizeMask; + + run_ind -= prun_size >> gPageSize2Pow; + + // Remove predecessor from tree of available runs; the coalesced run is + // inserted later. + mRunsAvail.Remove(&chunk->map[run_ind]); + + size += prun_size; + run_pages = size >> gPageSize2Pow; + + MOZ_DIAGNOSTIC_ASSERT((chunk->map[run_ind].bits & ~gPageSizeMask) == + prun_size); + chunk->map[run_ind].bits = + size | (chunk->map[run_ind].bits & gPageSizeMask); + chunk->map[run_ind + run_pages - 1].bits = + size | (chunk->map[run_ind + run_pages - 1].bits & gPageSizeMask); + } + + // Insert into tree of available runs, now that coalescing is complete. + mRunsAvail.Insert(&chunk->map[run_ind]); + + // Deallocate chunk if it is now completely unused. + arena_chunk_t* chunk_dealloc = nullptr; + if ((chunk->map[gChunkHeaderNumPages].bits & + (~gPageSizeMask | CHUNK_MAP_ALLOCATED)) == gMaxLargeClass) { + chunk_dealloc = DeallocChunk(chunk); + } + + size_t maxDirty = EffectiveMaxDirty(); + if (mNumDirty > maxDirty) { + Purge(maxDirty); + } + + return chunk_dealloc; +} + +void arena_t::TrimRunHead(arena_chunk_t* aChunk, arena_run_t* aRun, + size_t aOldSize, size_t aNewSize) { + size_t pageind = (uintptr_t(aRun) - uintptr_t(aChunk)) >> gPageSize2Pow; + size_t head_npages = (aOldSize - aNewSize) >> gPageSize2Pow; + + MOZ_ASSERT(aOldSize > aNewSize); + + // Update the chunk map so that arena_t::RunDalloc() can treat the + // leading run as separately allocated. + aChunk->map[pageind].bits = + (aOldSize - aNewSize) | CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + aChunk->map[pageind + head_npages].bits = + aNewSize | CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + +#ifdef MOZ_DEBUG + arena_chunk_t* no_chunk = +#endif + DallocRun(aRun, false); + // This will never release a chunk as there's still at least one allocated + // run. + MOZ_ASSERT(!no_chunk); +} + +void arena_t::TrimRunTail(arena_chunk_t* aChunk, arena_run_t* aRun, + size_t aOldSize, size_t aNewSize, bool aDirty) { + size_t pageind = (uintptr_t(aRun) - uintptr_t(aChunk)) >> gPageSize2Pow; + size_t npages = aNewSize >> gPageSize2Pow; + + MOZ_ASSERT(aOldSize > aNewSize); + + // Update the chunk map so that arena_t::RunDalloc() can treat the + // trailing run as separately allocated. + aChunk->map[pageind].bits = aNewSize | CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + aChunk->map[pageind + npages].bits = + (aOldSize - aNewSize) | CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + +#ifdef MOZ_DEBUG + arena_chunk_t* no_chunk = +#endif + DallocRun((arena_run_t*)(uintptr_t(aRun) + aNewSize), aDirty); + + // This will never release a chunk as there's still at least one allocated + // run. + MOZ_ASSERT(!no_chunk); +} + +arena_run_t* arena_t::GetNonFullBinRun(arena_bin_t* aBin) { + arena_chunk_map_t* mapelm; + arena_run_t* run; + unsigned i, remainder; + + // Look for a usable run. + mapelm = aBin->mNonFullRuns.First(); + if (mapelm) { + // run is guaranteed to have available space. + aBin->mNonFullRuns.Remove(mapelm); + run = (arena_run_t*)(mapelm->bits & ~gPageSizeMask); + return run; + } + // No existing runs have any space available. + + // Allocate a new run. + run = AllocRun(static_cast<size_t>(aBin->mRunSizePages) << gPageSize2Pow, + false, false); + if (!run) { + return nullptr; + } + // Don't initialize if a race in arena_t::RunAlloc() allowed an existing + // run to become usable. + if (run == aBin->mCurrentRun) { + return run; + } + + // Initialize run internals. + run->mBin = aBin; + + for (i = 0; i < aBin->mRunNumRegionsMask - 1; i++) { + run->mRegionsMask[i] = UINT_MAX; + } + remainder = aBin->mRunNumRegions & ((1U << (LOG2(sizeof(int)) + 3)) - 1); + if (remainder == 0) { + run->mRegionsMask[i] = UINT_MAX; + } else { + // The last element has spare bits that need to be unset. + run->mRegionsMask[i] = + (UINT_MAX >> ((1U << (LOG2(sizeof(int)) + 3)) - remainder)); + } + + run->mRegionsMinElement = 0; + + run->mNumFree = aBin->mRunNumRegions; +#if defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) + run->mMagic = ARENA_RUN_MAGIC; +#endif + + aBin->mNumRuns++; + return run; +} + +void arena_bin_t::Init(SizeClass aSizeClass) { + size_t try_run_size; + unsigned try_nregs, try_mask_nelms, try_reg0_offset; + // Size of the run header, excluding mRegionsMask. + static const size_t kFixedHeaderSize = offsetof(arena_run_t, mRegionsMask); + + MOZ_ASSERT(aSizeClass.Size() <= gMaxBinClass); + + try_run_size = gPageSize; + + mCurrentRun = nullptr; + mNonFullRuns.Init(); + mSizeClass = aSizeClass.Size(); + mNumRuns = 0; + + // Run size expansion loop. + while (true) { + try_nregs = ((try_run_size - kFixedHeaderSize) / mSizeClass) + + 1; // Counter-act try_nregs-- in loop. + + // The do..while loop iteratively reduces the number of regions until + // the run header and the regions no longer overlap. A closed formula + // would be quite messy, since there is an interdependency between the + // header's mask length and the number of regions. + do { + try_nregs--; + try_mask_nelms = + (try_nregs >> (LOG2(sizeof(int)) + 3)) + + ((try_nregs & ((1U << (LOG2(sizeof(int)) + 3)) - 1)) ? 1 : 0); + try_reg0_offset = try_run_size - (try_nregs * mSizeClass); + } while (kFixedHeaderSize + (sizeof(unsigned) * try_mask_nelms) > + try_reg0_offset); + + // Try to keep the run overhead below kRunOverhead. + if (Fraction(try_reg0_offset, try_run_size) <= kRunOverhead) { + break; + } + + // If the overhead is larger than the size class, it means the size class + // is small and doesn't align very well with the header. It's desirable to + // have smaller run sizes for them, so relax the overhead requirement. + if (try_reg0_offset > mSizeClass) { + if (Fraction(try_reg0_offset, try_run_size) <= kRunRelaxedOverhead) { + break; + } + } + + // The run header includes one bit per region of the given size. For sizes + // small enough, the number of regions is large enough that growing the run + // size barely moves the needle for the overhead because of all those bits. + // For example, for a size of 8 bytes, adding 4KiB to the run size adds + // close to 512 bits to the header, which is 64 bytes. + // With such overhead, there is no way to get to the wanted overhead above, + // so we give up if the required size for mRegionsMask more than doubles the + // size of the run header. + if (try_mask_nelms * sizeof(unsigned) >= kFixedHeaderSize) { + break; + } + + // If next iteration is going to be larger than the largest possible large + // size class, then we didn't find a setup where the overhead is small + // enough, and we can't do better than the current settings, so just use + // that. + if (try_run_size + gPageSize > gMaxLargeClass) { + break; + } + + // Try more aggressive settings. + try_run_size += gPageSize; + } + + MOZ_ASSERT(kFixedHeaderSize + (sizeof(unsigned) * try_mask_nelms) <= + try_reg0_offset); + MOZ_ASSERT((try_mask_nelms << (LOG2(sizeof(int)) + 3)) >= try_nregs); + + // Copy final settings. + MOZ_ASSERT((try_run_size >> gPageSize2Pow) <= UINT8_MAX); + mRunSizePages = static_cast<uint8_t>(try_run_size >> gPageSize2Pow); + mRunNumRegions = try_nregs; + mRunNumRegionsMask = try_mask_nelms; + mRunFirstRegionOffset = try_reg0_offset; + mSizeDivisor = FastDivisor<uint16_t>(aSizeClass.Size(), try_run_size); +} + +void* arena_t::MallocSmall(size_t aSize, bool aZero) { + void* ret; + arena_bin_t* bin; + arena_run_t* run; + SizeClass sizeClass(aSize); + aSize = sizeClass.Size(); + + switch (sizeClass.Type()) { + case SizeClass::Tiny: + bin = &mBins[FloorLog2(aSize / kMinTinyClass)]; + break; + case SizeClass::Quantum: + // Although we divide 2 things by kQuantum, the compiler will + // reduce `kMinQuantumClass / kQuantum` and `kNumTinyClasses` to a + // single constant. + bin = &mBins[kNumTinyClasses + (aSize / kQuantum) - + (kMinQuantumClass / kQuantum)]; + break; + case SizeClass::QuantumWide: + bin = + &mBins[kNumTinyClasses + kNumQuantumClasses + (aSize / kQuantumWide) - + (kMinQuantumWideClass / kQuantumWide)]; + break; + case SizeClass::SubPage: + bin = + &mBins[kNumTinyClasses + kNumQuantumClasses + kNumQuantumWideClasses + + (FloorLog2(aSize) - LOG2(kMinSubPageClass))]; + break; + default: + MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE("Unexpected size class type"); + } + MOZ_DIAGNOSTIC_ASSERT(aSize == bin->mSizeClass); + + { + // Before we lock, we determine if we need to randomize the allocation + // because if we do, we need to create the PRNG which might require + // allocating memory (arc4random on OSX for example) and we need to + // avoid the deadlock + if (MOZ_UNLIKELY(mRandomizeSmallAllocations && mPRNG == nullptr)) { + // This is frustrating. Because the code backing RandomUint64 (arc4random + // for example) may allocate memory, and because + // mRandomizeSmallAllocations is true and we haven't yet initilized mPRNG, + // we would re-enter this same case and cause a deadlock inside e.g. + // arc4random. So we temporarily disable mRandomizeSmallAllocations to + // skip this case and then re-enable it + mRandomizeSmallAllocations = false; + mozilla::Maybe<uint64_t> prngState1 = mozilla::RandomUint64(); + mozilla::Maybe<uint64_t> prngState2 = mozilla::RandomUint64(); + void* backing = + base_alloc(sizeof(mozilla::non_crypto::XorShift128PlusRNG)); + mPRNG = new (backing) mozilla::non_crypto::XorShift128PlusRNG( + prngState1.valueOr(0), prngState2.valueOr(0)); + mRandomizeSmallAllocations = true; + } + MOZ_ASSERT(!mRandomizeSmallAllocations || mPRNG); + + MaybeMutexAutoLock lock(mLock); + run = bin->mCurrentRun; + if (MOZ_UNLIKELY(!run || run->mNumFree == 0)) { + run = bin->mCurrentRun = GetNonFullBinRun(bin); + } + if (MOZ_UNLIKELY(!run)) { + return nullptr; + } + MOZ_DIAGNOSTIC_ASSERT(run->mMagic == ARENA_RUN_MAGIC); + MOZ_DIAGNOSTIC_ASSERT(run->mNumFree > 0); + ret = ArenaRunRegAlloc(run, bin); + MOZ_DIAGNOSTIC_ASSERT(ret); + run->mNumFree--; + if (!ret) { + return nullptr; + } + + mStats.allocated_small += aSize; + } + + if (!aZero) { + ApplyZeroOrJunk(ret, aSize); + } else { + memset(ret, 0, aSize); + } + + return ret; +} + +void* arena_t::MallocLarge(size_t aSize, bool aZero) { + void* ret; + + // Large allocation. + aSize = PAGE_CEILING(aSize); + + { + MaybeMutexAutoLock lock(mLock); + ret = AllocRun(aSize, true, aZero); + if (!ret) { + return nullptr; + } + mStats.allocated_large += aSize; + } + + if (!aZero) { + ApplyZeroOrJunk(ret, aSize); + } + + return ret; +} + +void* arena_t::Malloc(size_t aSize, bool aZero) { + MOZ_DIAGNOSTIC_ASSERT(mMagic == ARENA_MAGIC); + MOZ_ASSERT(aSize != 0); + + if (aSize <= gMaxBinClass) { + return MallocSmall(aSize, aZero); + } + if (aSize <= gMaxLargeClass) { + return MallocLarge(aSize, aZero); + } + return MallocHuge(aSize, aZero); +} + +// Only handles large allocations that require more than page alignment. +void* arena_t::PallocLarge(size_t aAlignment, size_t aSize, size_t aAllocSize) { + void* ret; + size_t offset; + arena_chunk_t* chunk; + + MOZ_ASSERT((aSize & gPageSizeMask) == 0); + MOZ_ASSERT((aAlignment & gPageSizeMask) == 0); + + { + MaybeMutexAutoLock lock(mLock); + ret = AllocRun(aAllocSize, true, false); + if (!ret) { + return nullptr; + } + + chunk = GetChunkForPtr(ret); + + offset = uintptr_t(ret) & (aAlignment - 1); + MOZ_ASSERT((offset & gPageSizeMask) == 0); + MOZ_ASSERT(offset < aAllocSize); + if (offset == 0) { + TrimRunTail(chunk, (arena_run_t*)ret, aAllocSize, aSize, false); + } else { + size_t leadsize, trailsize; + + leadsize = aAlignment - offset; + if (leadsize > 0) { + TrimRunHead(chunk, (arena_run_t*)ret, aAllocSize, + aAllocSize - leadsize); + ret = (void*)(uintptr_t(ret) + leadsize); + } + + trailsize = aAllocSize - leadsize - aSize; + if (trailsize != 0) { + // Trim trailing space. + MOZ_ASSERT(trailsize < aAllocSize); + TrimRunTail(chunk, (arena_run_t*)ret, aSize + trailsize, aSize, false); + } + } + + mStats.allocated_large += aSize; + } + + ApplyZeroOrJunk(ret, aSize); + return ret; +} + +void* arena_t::Palloc(size_t aAlignment, size_t aSize) { + void* ret; + size_t ceil_size; + + // Round size up to the nearest multiple of alignment. + // + // This done, we can take advantage of the fact that for each small + // size class, every object is aligned at the smallest power of two + // that is non-zero in the base two representation of the size. For + // example: + // + // Size | Base 2 | Minimum alignment + // -----+----------+------------------ + // 96 | 1100000 | 32 + // 144 | 10100000 | 32 + // 192 | 11000000 | 64 + // + // Depending on runtime settings, it is possible that arena_malloc() + // will further round up to a power of two, but that never causes + // correctness issues. + ceil_size = ALIGNMENT_CEILING(aSize, aAlignment); + + // (ceil_size < aSize) protects against the combination of maximal + // alignment and size greater than maximal alignment. + if (ceil_size < aSize) { + // size_t overflow. + return nullptr; + } + + if (ceil_size <= gPageSize || + (aAlignment <= gPageSize && ceil_size <= gMaxLargeClass)) { + ret = Malloc(ceil_size, false); + } else { + size_t run_size; + + // We can't achieve sub-page alignment, so round up alignment + // permanently; it makes later calculations simpler. + aAlignment = PAGE_CEILING(aAlignment); + ceil_size = PAGE_CEILING(aSize); + + // (ceil_size < aSize) protects against very large sizes within + // pagesize of SIZE_T_MAX. + // + // (ceil_size + aAlignment < ceil_size) protects against the + // combination of maximal alignment and ceil_size large enough + // to cause overflow. This is similar to the first overflow + // check above, but it needs to be repeated due to the new + // ceil_size value, which may now be *equal* to maximal + // alignment, whereas before we only detected overflow if the + // original size was *greater* than maximal alignment. + if (ceil_size < aSize || ceil_size + aAlignment < ceil_size) { + // size_t overflow. + return nullptr; + } + + // Calculate the size of the over-size run that arena_palloc() + // would need to allocate in order to guarantee the alignment. + if (ceil_size >= aAlignment) { + run_size = ceil_size + aAlignment - gPageSize; + } else { + // It is possible that (aAlignment << 1) will cause + // overflow, but it doesn't matter because we also + // subtract pagesize, which in the case of overflow + // leaves us with a very large run_size. That causes + // the first conditional below to fail, which means + // that the bogus run_size value never gets used for + // anything important. + run_size = (aAlignment << 1) - gPageSize; + } + + if (run_size <= gMaxLargeClass) { + ret = PallocLarge(aAlignment, ceil_size, run_size); + } else if (aAlignment <= kChunkSize) { + ret = MallocHuge(ceil_size, false); + } else { + ret = PallocHuge(ceil_size, aAlignment, false); + } + } + + MOZ_ASSERT((uintptr_t(ret) & (aAlignment - 1)) == 0); + return ret; +} + +class AllocInfo { + public: + template <bool Validate = false> + static inline AllocInfo Get(const void* aPtr) { + // If the allocator is not initialized, the pointer can't belong to it. + if (Validate && !malloc_initialized) { + return AllocInfo(); + } + + auto chunk = GetChunkForPtr(aPtr); + if (Validate) { + if (!chunk || !gChunkRTree.Get(chunk)) { + return AllocInfo(); + } + } + + if (chunk != aPtr) { + MOZ_DIAGNOSTIC_ASSERT(chunk->arena->mMagic == ARENA_MAGIC); + size_t pageind = (((uintptr_t)aPtr - (uintptr_t)chunk) >> gPageSize2Pow); + return GetInChunk(aPtr, chunk, pageind); + } + + extent_node_t key; + + // Huge allocation + key.mAddr = chunk; + MutexAutoLock lock(huge_mtx); + extent_node_t* node = huge.Search(&key); + if (Validate && !node) { + return AllocInfo(); + } + return AllocInfo(node->mSize, node); + } + + // Get the allocation information for a pointer we know is within a chunk + // (Small or large, not huge). + static inline AllocInfo GetInChunk(const void* aPtr, arena_chunk_t* aChunk, + size_t pageind) { + size_t mapbits = aChunk->map[pageind].bits; + MOZ_DIAGNOSTIC_ASSERT((mapbits & CHUNK_MAP_ALLOCATED) != 0); + + size_t size; + if ((mapbits & CHUNK_MAP_LARGE) == 0) { + arena_run_t* run = (arena_run_t*)(mapbits & ~gPageSizeMask); + MOZ_DIAGNOSTIC_ASSERT(run->mMagic == ARENA_RUN_MAGIC); + size = run->mBin->mSizeClass; + } else { + size = mapbits & ~gPageSizeMask; + MOZ_DIAGNOSTIC_ASSERT(size != 0); + } + + return AllocInfo(size, aChunk); + } + + // Validate ptr before assuming that it points to an allocation. Currently, + // the following validation is performed: + // + // + Check that ptr is not nullptr. + // + // + Check that ptr lies within a mapped chunk. + static inline AllocInfo GetValidated(const void* aPtr) { + return Get<true>(aPtr); + } + + AllocInfo() : mSize(0), mChunk(nullptr) {} + + explicit AllocInfo(size_t aSize, arena_chunk_t* aChunk) + : mSize(aSize), mChunk(aChunk) { + MOZ_ASSERT(mSize <= gMaxLargeClass); + } + + explicit AllocInfo(size_t aSize, extent_node_t* aNode) + : mSize(aSize), mNode(aNode) { + MOZ_ASSERT(mSize > gMaxLargeClass); + } + + size_t Size() { return mSize; } + + arena_t* Arena() { + if (mSize <= gMaxLargeClass) { + return mChunk->arena; + } + // Best effort detection that we're not trying to access an already + // disposed arena. In the case of a disposed arena, the memory location + // pointed by mNode->mArena is either free (but still a valid memory + // region, per TypedBaseAlloc<arena_t>), in which case its id was reset, + // or has been reallocated for a new region, and its id is very likely + // different (per randomness). In both cases, the id is unlikely to + // match what it was for the disposed arena. + MOZ_RELEASE_ASSERT(mNode->mArenaId == mNode->mArena->mId); + return mNode->mArena; + } + + bool IsValid() const { return !!mSize; } + + private: + size_t mSize; + union { + // Pointer to the chunk associated with the allocation for small + // and large allocations. + arena_chunk_t* mChunk; + + // Pointer to the extent node for huge allocations. + extent_node_t* mNode; + }; +}; + +inline void MozJemalloc::jemalloc_ptr_info(const void* aPtr, + jemalloc_ptr_info_t* aInfo) { + arena_chunk_t* chunk = GetChunkForPtr(aPtr); + + // Is the pointer null, or within one chunk's size of null? + // Alternatively, if the allocator is not initialized yet, the pointer + // can't be known. + if (!chunk || !malloc_initialized) { + *aInfo = {TagUnknown, nullptr, 0, 0}; + return; + } + + // Look for huge allocations before looking for |chunk| in gChunkRTree. + // This is necessary because |chunk| won't be in gChunkRTree if it's + // the second or subsequent chunk in a huge allocation. + extent_node_t* node; + extent_node_t key; + { + MutexAutoLock lock(huge_mtx); + key.mAddr = const_cast<void*>(aPtr); + node = + reinterpret_cast<RedBlackTree<extent_node_t, ExtentTreeBoundsTrait>*>( + &huge) + ->Search(&key); + if (node) { + *aInfo = {TagLiveAlloc, node->mAddr, node->mSize, node->mArena->mId}; + return; + } + } + + // It's not a huge allocation. Check if we have a known chunk. + if (!gChunkRTree.Get(chunk)) { + *aInfo = {TagUnknown, nullptr, 0, 0}; + return; + } + + MOZ_DIAGNOSTIC_ASSERT(chunk->arena->mMagic == ARENA_MAGIC); + + // Get the page number within the chunk. + size_t pageind = (((uintptr_t)aPtr - (uintptr_t)chunk) >> gPageSize2Pow); + if (pageind < gChunkHeaderNumPages) { + // Within the chunk header. + *aInfo = {TagUnknown, nullptr, 0, 0}; + return; + } + + size_t mapbits = chunk->map[pageind].bits; + + if (!(mapbits & CHUNK_MAP_ALLOCATED)) { + void* pageaddr = (void*)(uintptr_t(aPtr) & ~gPageSizeMask); + *aInfo = {TagFreedPage, pageaddr, gPageSize, chunk->arena->mId}; + return; + } + + if (mapbits & CHUNK_MAP_LARGE) { + // It's a large allocation. Only the first page of a large + // allocation contains its size, so if the address is not in + // the first page, scan back to find the allocation size. + size_t size; + while (true) { + size = mapbits & ~gPageSizeMask; + if (size != 0) { + break; + } + + // The following two return paths shouldn't occur in + // practice unless there is heap corruption. + pageind--; + MOZ_DIAGNOSTIC_ASSERT(pageind >= gChunkHeaderNumPages); + if (pageind < gChunkHeaderNumPages) { + *aInfo = {TagUnknown, nullptr, 0, 0}; + return; + } + + mapbits = chunk->map[pageind].bits; + MOZ_DIAGNOSTIC_ASSERT(mapbits & CHUNK_MAP_LARGE); + if (!(mapbits & CHUNK_MAP_LARGE)) { + *aInfo = {TagUnknown, nullptr, 0, 0}; + return; + } + } + + void* addr = ((char*)chunk) + (pageind << gPageSize2Pow); + *aInfo = {TagLiveAlloc, addr, size, chunk->arena->mId}; + return; + } + + // It must be a small allocation. + auto run = (arena_run_t*)(mapbits & ~gPageSizeMask); + MOZ_DIAGNOSTIC_ASSERT(run->mMagic == ARENA_RUN_MAGIC); + + // The allocation size is stored in the run metadata. + size_t size = run->mBin->mSizeClass; + + // Address of the first possible pointer in the run after its headers. + uintptr_t reg0_addr = (uintptr_t)run + run->mBin->mRunFirstRegionOffset; + if (aPtr < (void*)reg0_addr) { + // In the run header. + *aInfo = {TagUnknown, nullptr, 0, 0}; + return; + } + + // Position in the run. + unsigned regind = ((uintptr_t)aPtr - reg0_addr) / size; + + // Pointer to the allocation's base address. + void* addr = (void*)(reg0_addr + regind * size); + + // Check if the allocation has been freed. + unsigned elm = regind >> (LOG2(sizeof(int)) + 3); + unsigned bit = regind - (elm << (LOG2(sizeof(int)) + 3)); + PtrInfoTag tag = + ((run->mRegionsMask[elm] & (1U << bit))) ? TagFreedAlloc : TagLiveAlloc; + + *aInfo = {tag, addr, size, chunk->arena->mId}; +} + +namespace Debug { +// Helper for debuggers. We don't want it to be inlined and optimized out. +MOZ_NEVER_INLINE jemalloc_ptr_info_t* jemalloc_ptr_info(const void* aPtr) { + static jemalloc_ptr_info_t info; + MozJemalloc::jemalloc_ptr_info(aPtr, &info); + return &info; +} +} // namespace Debug + +arena_chunk_t* arena_t::DallocSmall(arena_chunk_t* aChunk, void* aPtr, + arena_chunk_map_t* aMapElm) { + arena_run_t* run; + arena_bin_t* bin; + size_t size; + + run = (arena_run_t*)(aMapElm->bits & ~gPageSizeMask); + MOZ_DIAGNOSTIC_ASSERT(run->mMagic == ARENA_RUN_MAGIC); + bin = run->mBin; + size = bin->mSizeClass; + MOZ_DIAGNOSTIC_ASSERT(uintptr_t(aPtr) >= + uintptr_t(run) + bin->mRunFirstRegionOffset); + + arena_run_reg_dalloc(run, bin, aPtr, size); + run->mNumFree++; + arena_chunk_t* dealloc_chunk = nullptr; + + if (run->mNumFree == bin->mRunNumRegions) { + // Deallocate run. + if (run == bin->mCurrentRun) { + bin->mCurrentRun = nullptr; + } else if (bin->mRunNumRegions != 1) { + size_t run_pageind = + (uintptr_t(run) - uintptr_t(aChunk)) >> gPageSize2Pow; + arena_chunk_map_t* run_mapelm = &aChunk->map[run_pageind]; + + // This block's conditional is necessary because if the + // run only contains one region, then it never gets + // inserted into the non-full runs tree. + MOZ_DIAGNOSTIC_ASSERT(bin->mNonFullRuns.Search(run_mapelm) == run_mapelm); + bin->mNonFullRuns.Remove(run_mapelm); + } +#if defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) + run->mMagic = 0; +#endif + dealloc_chunk = DallocRun(run, true); + bin->mNumRuns--; + } else if (run->mNumFree == 1 && run != bin->mCurrentRun) { + // Make sure that bin->mCurrentRun always refers to the lowest + // non-full run, if one exists. + if (!bin->mCurrentRun) { + bin->mCurrentRun = run; + } else if (uintptr_t(run) < uintptr_t(bin->mCurrentRun)) { + // Switch mCurrentRun. + if (bin->mCurrentRun->mNumFree > 0) { + arena_chunk_t* runcur_chunk = GetChunkForPtr(bin->mCurrentRun); + size_t runcur_pageind = + (uintptr_t(bin->mCurrentRun) - uintptr_t(runcur_chunk)) >> + gPageSize2Pow; + arena_chunk_map_t* runcur_mapelm = &runcur_chunk->map[runcur_pageind]; + + // Insert runcur. + MOZ_DIAGNOSTIC_ASSERT(!bin->mNonFullRuns.Search(runcur_mapelm)); + bin->mNonFullRuns.Insert(runcur_mapelm); + } + bin->mCurrentRun = run; + } else { + size_t run_pageind = + (uintptr_t(run) - uintptr_t(aChunk)) >> gPageSize2Pow; + arena_chunk_map_t* run_mapelm = &aChunk->map[run_pageind]; + + MOZ_DIAGNOSTIC_ASSERT(bin->mNonFullRuns.Search(run_mapelm) == nullptr); + bin->mNonFullRuns.Insert(run_mapelm); + } + } + mStats.allocated_small -= size; + + return dealloc_chunk; +} + +arena_chunk_t* arena_t::DallocLarge(arena_chunk_t* aChunk, void* aPtr) { + MOZ_DIAGNOSTIC_ASSERT((uintptr_t(aPtr) & gPageSizeMask) == 0); + size_t pageind = (uintptr_t(aPtr) - uintptr_t(aChunk)) >> gPageSize2Pow; + size_t size = aChunk->map[pageind].bits & ~gPageSizeMask; + + mStats.allocated_large -= size; + + return DallocRun((arena_run_t*)aPtr, true); +} + +static inline void arena_dalloc(void* aPtr, size_t aOffset, arena_t* aArena) { + MOZ_ASSERT(aPtr); + MOZ_ASSERT(aOffset != 0); + MOZ_ASSERT(GetChunkOffsetForPtr(aPtr) == aOffset); + + auto chunk = (arena_chunk_t*)((uintptr_t)aPtr - aOffset); + auto arena = chunk->arena; + MOZ_ASSERT(arena); + MOZ_DIAGNOSTIC_ASSERT(arena->mMagic == ARENA_MAGIC); + MOZ_RELEASE_ASSERT(!aArena || arena == aArena); + + size_t pageind = aOffset >> gPageSize2Pow; + if (opt_poison) { + AllocInfo info = AllocInfo::GetInChunk(aPtr, chunk, pageind); + MOZ_ASSERT(info.IsValid()); + MaybePoison(aPtr, info.Size()); + } + + arena_chunk_t* chunk_dealloc_delay = nullptr; + + { + MaybeMutexAutoLock lock(arena->mLock); + arena_chunk_map_t* mapelm = &chunk->map[pageind]; + MOZ_RELEASE_ASSERT((mapelm->bits & CHUNK_MAP_DECOMMITTED) == 0, + "Freeing in decommitted page."); + MOZ_RELEASE_ASSERT((mapelm->bits & CHUNK_MAP_ALLOCATED) != 0, + "Double-free?"); + if ((mapelm->bits & CHUNK_MAP_LARGE) == 0) { + // Small allocation. + chunk_dealloc_delay = arena->DallocSmall(chunk, aPtr, mapelm); + } else { + // Large allocation. + chunk_dealloc_delay = arena->DallocLarge(chunk, aPtr); + } + } + + if (chunk_dealloc_delay) { + chunk_dealloc((void*)chunk_dealloc_delay, kChunkSize, ARENA_CHUNK); + } +} + +static inline void idalloc(void* ptr, arena_t* aArena) { + size_t offset; + + MOZ_ASSERT(ptr); + + offset = GetChunkOffsetForPtr(ptr); + if (offset != 0) { + arena_dalloc(ptr, offset, aArena); + } else { + huge_dalloc(ptr, aArena); + } +} + +void arena_t::RallocShrinkLarge(arena_chunk_t* aChunk, void* aPtr, size_t aSize, + size_t aOldSize) { + MOZ_ASSERT(aSize < aOldSize); + + // Shrink the run, and make trailing pages available for other + // allocations. + MaybeMutexAutoLock lock(mLock); + TrimRunTail(aChunk, (arena_run_t*)aPtr, aOldSize, aSize, true); + mStats.allocated_large -= aOldSize - aSize; +} + +// Returns whether reallocation was successful. +bool arena_t::RallocGrowLarge(arena_chunk_t* aChunk, void* aPtr, size_t aSize, + size_t aOldSize) { + size_t pageind = (uintptr_t(aPtr) - uintptr_t(aChunk)) >> gPageSize2Pow; + size_t npages = aOldSize >> gPageSize2Pow; + + MaybeMutexAutoLock lock(mLock); + MOZ_DIAGNOSTIC_ASSERT(aOldSize == + (aChunk->map[pageind].bits & ~gPageSizeMask)); + + // Try to extend the run. + MOZ_ASSERT(aSize > aOldSize); + if (pageind + npages < gChunkNumPages - 1 && + (aChunk->map[pageind + npages].bits & CHUNK_MAP_ALLOCATED) == 0 && + (aChunk->map[pageind + npages].bits & ~gPageSizeMask) >= + aSize - aOldSize) { + // The next run is available and sufficiently large. Split the + // following run, then merge the first part with the existing + // allocation. + if (!SplitRun((arena_run_t*)(uintptr_t(aChunk) + + ((pageind + npages) << gPageSize2Pow)), + aSize - aOldSize, true, false)) { + return false; + } + + aChunk->map[pageind].bits = aSize | CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + aChunk->map[pageind + npages].bits = CHUNK_MAP_LARGE | CHUNK_MAP_ALLOCATED; + + mStats.allocated_large += aSize - aOldSize; + return true; + } + + return false; +} + +void* arena_t::RallocSmallOrLarge(void* aPtr, size_t aSize, size_t aOldSize) { + void* ret; + size_t copysize; + SizeClass sizeClass(aSize); + + // Try to avoid moving the allocation. + if (aOldSize <= gMaxLargeClass && sizeClass.Size() == aOldSize) { + if (aSize < aOldSize) { + MaybePoison((void*)(uintptr_t(aPtr) + aSize), aOldSize - aSize); + } + return aPtr; + } + if (sizeClass.Type() == SizeClass::Large && aOldSize > gMaxBinClass && + aOldSize <= gMaxLargeClass) { + arena_chunk_t* chunk = GetChunkForPtr(aPtr); + if (sizeClass.Size() < aOldSize) { + // Fill before shrinking in order to avoid a race. + MaybePoison((void*)((uintptr_t)aPtr + aSize), aOldSize - aSize); + RallocShrinkLarge(chunk, aPtr, sizeClass.Size(), aOldSize); + return aPtr; + } + if (RallocGrowLarge(chunk, aPtr, sizeClass.Size(), aOldSize)) { + ApplyZeroOrJunk((void*)((uintptr_t)aPtr + aOldSize), aSize - aOldSize); + return aPtr; + } + } + + // If we get here, then aSize and aOldSize are different enough that we + // need to move the object. In that case, fall back to allocating new + // space and copying. Allow non-private arenas to switch arenas. + ret = (mIsPrivate ? this : choose_arena(aSize))->Malloc(aSize, false); + if (!ret) { + return nullptr; + } + + // Junk/zero-filling were already done by arena_t::Malloc(). + copysize = (aSize < aOldSize) ? aSize : aOldSize; +#ifdef VM_COPY_MIN + if (copysize >= VM_COPY_MIN) { + pages_copy(ret, aPtr, copysize); + } else +#endif + { + memcpy(ret, aPtr, copysize); + } + idalloc(aPtr, this); + return ret; +} + +void* arena_t::Ralloc(void* aPtr, size_t aSize, size_t aOldSize) { + MOZ_DIAGNOSTIC_ASSERT(mMagic == ARENA_MAGIC); + MOZ_ASSERT(aPtr); + MOZ_ASSERT(aSize != 0); + + return (aSize <= gMaxLargeClass) ? RallocSmallOrLarge(aPtr, aSize, aOldSize) + : RallocHuge(aPtr, aSize, aOldSize); +} + +void* arena_t::operator new(size_t aCount, const fallible_t&) noexcept { + MOZ_ASSERT(aCount == sizeof(arena_t)); + return TypedBaseAlloc<arena_t>::alloc(); +} + +void arena_t::operator delete(void* aPtr) { + TypedBaseAlloc<arena_t>::dealloc((arena_t*)aPtr); +} + +arena_t::arena_t(arena_params_t* aParams, bool aIsPrivate) { + unsigned i; + + memset(&mLink, 0, sizeof(mLink)); + memset(&mStats, 0, sizeof(arena_stats_t)); + mId = 0; + + // Initialize chunks. + mChunksDirty.Init(); +#ifdef MALLOC_DOUBLE_PURGE + new (&mChunksMAdvised) DoublyLinkedList<arena_chunk_t>(); +#endif + mSpare = nullptr; + + mRandomizeSmallAllocations = opt_randomize_small; + MaybeMutex::DoLock doLock = MaybeMutex::MUST_LOCK; + if (aParams) { + uint32_t randFlags = aParams->mFlags & ARENA_FLAG_RANDOMIZE_SMALL_MASK; + switch (randFlags) { + case ARENA_FLAG_RANDOMIZE_SMALL_ENABLED: + mRandomizeSmallAllocations = true; + break; + case ARENA_FLAG_RANDOMIZE_SMALL_DISABLED: + mRandomizeSmallAllocations = false; + break; + case ARENA_FLAG_RANDOMIZE_SMALL_DEFAULT: + default: + break; + } + + uint32_t threadFlags = aParams->mFlags & ARENA_FLAG_THREAD_MASK; + if (threadFlags == ARENA_FLAG_THREAD_MAIN_THREAD_ONLY) { + // At the moment we require that any ARENA_FLAG_THREAD_MAIN_THREAD_ONLY + // arenas are created and therefore always accessed by the main thread. + // This is for two reasons: + // * it allows jemalloc_stats to read their statistics (we also require + // that jemalloc_stats is only used on the main thread). + // * Only main-thread or threadsafe arenas can be guanteed to be in a + // consistent state after a fork() from the main thread. If fork() + // occurs off-thread then the new child process cannot use these arenas + // (new children should usually exec() or exit() since other data may + // also be inconsistent). + MOZ_ASSERT(gArenas.IsOnMainThread()); + MOZ_ASSERT(aIsPrivate); + doLock = MaybeMutex::AVOID_LOCK_UNSAFE; + } + + mMaxDirtyIncreaseOverride = aParams->mMaxDirtyIncreaseOverride; + mMaxDirtyDecreaseOverride = aParams->mMaxDirtyDecreaseOverride; + } else { + mMaxDirtyIncreaseOverride = 0; + mMaxDirtyDecreaseOverride = 0; + } + + MOZ_RELEASE_ASSERT(mLock.Init(doLock)); + + mPRNG = nullptr; + + mIsPrivate = aIsPrivate; + + mNumDirty = 0; + // The default maximum amount of dirty pages allowed on arenas is a fraction + // of opt_dirty_max. + mMaxDirty = (aParams && aParams->mMaxDirty) ? aParams->mMaxDirty + : (opt_dirty_max / 8); + + mRunsAvail.Init(); + + // Initialize bins. + SizeClass sizeClass(1); + + for (i = 0;; i++) { + arena_bin_t& bin = mBins[i]; + bin.Init(sizeClass); + + // SizeClass doesn't want sizes larger than gMaxBinClass for now. + if (sizeClass.Size() == gMaxBinClass) { + break; + } + sizeClass = sizeClass.Next(); + } + MOZ_ASSERT(i == NUM_SMALL_CLASSES - 1); + +#if defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED) + mMagic = ARENA_MAGIC; +#endif +} + +arena_t::~arena_t() { + size_t i; + MaybeMutexAutoLock lock(mLock); + MOZ_RELEASE_ASSERT(!mLink.Left() && !mLink.Right(), + "Arena is still registered"); + MOZ_RELEASE_ASSERT(!mStats.allocated_small && !mStats.allocated_large, + "Arena is not empty"); + if (mSpare) { + chunk_dealloc(mSpare, kChunkSize, ARENA_CHUNK); + } + for (i = 0; i < NUM_SMALL_CLASSES; i++) { + MOZ_RELEASE_ASSERT(!mBins[i].mNonFullRuns.First(), "Bin is not empty"); + } +#ifdef MOZ_DEBUG + { + MutexAutoLock lock(huge_mtx); + // This is an expensive check, so we only do it on debug builds. + for (auto node : huge.iter()) { + MOZ_RELEASE_ASSERT(node->mArenaId != mId, "Arena has huge allocations"); + } + } +#endif + mId = 0; +} + +arena_t* ArenaCollection::CreateArena(bool aIsPrivate, + arena_params_t* aParams) { + arena_t* ret = new (fallible) arena_t(aParams, aIsPrivate); + if (!ret) { + // Only reached if there is an OOM error. + + // OOM here is quite inconvenient to propagate, since dealing with it + // would require a check for failure in the fast path. Instead, punt + // by using the first arena. + // In practice, this is an extremely unlikely failure. + _malloc_message(_getprogname(), ": (malloc) Error initializing arena\n"); + + return mDefaultArena; + } + + MutexAutoLock lock(mLock); + + // For public arenas, it's fine to just use incrementing arena id + if (!aIsPrivate) { + ret->mId = mLastPublicArenaId++; + mArenas.Insert(ret); + return ret; + } + + // For private arenas, generate a cryptographically-secure random id for the + // new arena. If an attacker manages to get control of the process, this + // should make it more difficult for them to "guess" the ID of a memory + // arena, stopping them from getting data they may want + Tree& tree = (ret->IsMainThreadOnly()) ? mMainThreadArenas : mPrivateArenas; + arena_id_t arena_id; + do { + arena_id = MakeRandArenaId(ret->IsMainThreadOnly()); + // Keep looping until we ensure that the random number we just generated + // isn't already in use by another active arena + } while (GetByIdInternal(tree, arena_id)); + + ret->mId = arena_id; + tree.Insert(ret); + return ret; +} + +arena_id_t ArenaCollection::MakeRandArenaId(bool aIsMainThreadOnly) const { + uint64_t rand; + do { + mozilla::Maybe<uint64_t> maybeRandomId = mozilla::RandomUint64(); + MOZ_RELEASE_ASSERT(maybeRandomId.isSome()); + + rand = maybeRandomId.value(); + + // Set or clear the least significant bit depending on if this is a + // main-thread-only arena. We use this in GetById. + if (aIsMainThreadOnly) { + rand = rand | MAIN_THREAD_ARENA_BIT; + } else { + rand = rand & ~MAIN_THREAD_ARENA_BIT; + } + + // Avoid 0 as an arena Id. We use 0 for disposed arenas. + } while (rand == 0); + + return arena_id_t(rand); +} + +// End arena. +// *************************************************************************** +// Begin general internal functions. + +void* arena_t::MallocHuge(size_t aSize, bool aZero) { + return PallocHuge(aSize, kChunkSize, aZero); +} + +void* arena_t::PallocHuge(size_t aSize, size_t aAlignment, bool aZero) { + void* ret; + size_t csize; + size_t psize; + extent_node_t* node; + + // We're going to configure guard pages in the region between the + // page-aligned size and the chunk-aligned size, so if those are the same + // then we need to force that region into existence. + csize = CHUNK_CEILING(aSize + gPageSize); + if (csize < aSize) { + // size is large enough to cause size_t wrap-around. + return nullptr; + } + + // Allocate an extent node with which to track the chunk. + node = ExtentAlloc::alloc(); + if (!node) { + return nullptr; + } + + // Allocate one or more contiguous chunks for this request. + ret = chunk_alloc(csize, aAlignment, false); + if (!ret) { + ExtentAlloc::dealloc(node); + return nullptr; + } + psize = PAGE_CEILING(aSize); +#ifdef MOZ_DEBUG + if (aZero) { + chunk_assert_zero(ret, psize); + } +#endif + + // Insert node into huge. + node->mAddr = ret; + node->mSize = psize; + node->mArena = this; + node->mArenaId = mId; + + { + MutexAutoLock lock(huge_mtx); + huge.Insert(node); + + // Although we allocated space for csize bytes, we indicate that we've + // allocated only psize bytes. + // + // If DECOMMIT is defined, this is a reasonable thing to do, since + // we'll explicitly decommit the bytes in excess of psize. + // + // If DECOMMIT is not defined, then we're relying on the OS to be lazy + // about how it allocates physical pages to mappings. If we never + // touch the pages in excess of psize, the OS won't allocate a physical + // page, and we won't use more than psize bytes of physical memory. + // + // A correct program will only touch memory in excess of how much it + // requested if it first calls malloc_usable_size and finds out how + // much space it has to play with. But because we set node->mSize = + // psize above, malloc_usable_size will return psize, not csize, and + // the program will (hopefully) never touch bytes in excess of psize. + // Thus those bytes won't take up space in physical memory, and we can + // reasonably claim we never "allocated" them in the first place. + huge_allocated += psize; + huge_mapped += csize; + } + + pages_decommit((void*)((uintptr_t)ret + psize), csize - psize); + + if (!aZero) { + ApplyZeroOrJunk(ret, psize); + } + + return ret; +} + +void* arena_t::RallocHuge(void* aPtr, size_t aSize, size_t aOldSize) { + void* ret; + size_t copysize; + + // Avoid moving the allocation if the size class would not change. + if (aOldSize > gMaxLargeClass && + CHUNK_CEILING(aSize + gPageSize) == CHUNK_CEILING(aOldSize + gPageSize)) { + size_t psize = PAGE_CEILING(aSize); + if (aSize < aOldSize) { + MaybePoison((void*)((uintptr_t)aPtr + aSize), aOldSize - aSize); + } + if (psize < aOldSize) { + extent_node_t key; + + pages_decommit((void*)((uintptr_t)aPtr + psize), aOldSize - psize); + + // Update recorded size. + MutexAutoLock lock(huge_mtx); + key.mAddr = const_cast<void*>(aPtr); + extent_node_t* node = huge.Search(&key); + MOZ_ASSERT(node); + MOZ_ASSERT(node->mSize == aOldSize); + MOZ_RELEASE_ASSERT(node->mArena == this); + huge_allocated -= aOldSize - psize; + // No need to change huge_mapped, because we didn't (un)map anything. + node->mSize = psize; + } else if (psize > aOldSize) { + if (!pages_commit((void*)((uintptr_t)aPtr + aOldSize), + psize - aOldSize)) { + return nullptr; + } + + // We need to update the recorded size if the size increased, + // so malloc_usable_size doesn't return a value smaller than + // what was requested via realloc(). + extent_node_t key; + MutexAutoLock lock(huge_mtx); + key.mAddr = const_cast<void*>(aPtr); + extent_node_t* node = huge.Search(&key); + MOZ_ASSERT(node); + MOZ_ASSERT(node->mSize == aOldSize); + MOZ_RELEASE_ASSERT(node->mArena == this); + huge_allocated += psize - aOldSize; + // No need to change huge_mapped, because we didn't + // (un)map anything. + node->mSize = psize; + } + + if (aSize > aOldSize) { + ApplyZeroOrJunk((void*)((uintptr_t)aPtr + aOldSize), aSize - aOldSize); + } + return aPtr; + } + + // If we get here, then aSize and aOldSize are different enough that we + // need to use a different size class. In that case, fall back to allocating + // new space and copying. Allow non-private arenas to switch arenas. + ret = (mIsPrivate ? this : choose_arena(aSize))->MallocHuge(aSize, false); + if (!ret) { + return nullptr; + } + + copysize = (aSize < aOldSize) ? aSize : aOldSize; +#ifdef VM_COPY_MIN + if (copysize >= VM_COPY_MIN) { + pages_copy(ret, aPtr, copysize); + } else +#endif + { + memcpy(ret, aPtr, copysize); + } + idalloc(aPtr, this); + return ret; +} + +static void huge_dalloc(void* aPtr, arena_t* aArena) { + extent_node_t* node; + size_t mapped = 0; + { + extent_node_t key; + MutexAutoLock lock(huge_mtx); + + // Extract from tree of huge allocations. + key.mAddr = aPtr; + node = huge.Search(&key); + MOZ_RELEASE_ASSERT(node, "Double-free?"); + MOZ_ASSERT(node->mAddr == aPtr); + MOZ_RELEASE_ASSERT(!aArena || node->mArena == aArena); + // See AllocInfo::Arena. + MOZ_RELEASE_ASSERT(node->mArenaId == node->mArena->mId); + huge.Remove(node); + + mapped = CHUNK_CEILING(node->mSize + gPageSize); + huge_allocated -= node->mSize; + huge_mapped -= mapped; + } + + // Unmap chunk. + chunk_dealloc(node->mAddr, mapped, HUGE_CHUNK); + + ExtentAlloc::dealloc(node); +} + +size_t GetKernelPageSize() { + static size_t kernel_page_size = ([]() { +#ifdef XP_WIN + SYSTEM_INFO info; + GetSystemInfo(&info); + return info.dwPageSize; +#else + long result = sysconf(_SC_PAGESIZE); + MOZ_ASSERT(result != -1); + return result; +#endif + })(); + return kernel_page_size; +} + +// Returns whether the allocator was successfully initialized. +static bool malloc_init_hard() { + unsigned i; + const char* opts; + + AutoLock<StaticMutex> lock(gInitLock); + + if (malloc_initialized) { + // Another thread initialized the allocator before this one + // acquired gInitLock. + return true; + } + + if (!thread_arena.init()) { + return true; + } + + // Get page size and number of CPUs + const size_t page_size = GetKernelPageSize(); + // We assume that the page size is a power of 2. + MOZ_ASSERT(IsPowerOfTwo(page_size)); +#ifdef MALLOC_STATIC_PAGESIZE + if (gPageSize % page_size) { + _malloc_message( + _getprogname(), + "Compile-time page size does not divide the runtime one.\n"); + MOZ_CRASH(); + } +#else + gRealPageSize = gPageSize = page_size; +#endif + + // Get runtime configuration. + if ((opts = getenv("MALLOC_OPTIONS"))) { + for (i = 0; opts[i] != '\0'; i++) { + // All options are single letters, some take a *prefix* numeric argument. + + // Parse the argument. + unsigned prefix_arg = 0; + while (opts[i] >= '0' && opts[i] <= '9') { + prefix_arg *= 10; + prefix_arg += opts[i] - '0'; + i++; + } + + switch (opts[i]) { + case 'f': + opt_dirty_max >>= prefix_arg ? prefix_arg : 1; + break; + case 'F': + prefix_arg = prefix_arg ? prefix_arg : 1; + if (opt_dirty_max == 0) { + opt_dirty_max = 1; + prefix_arg--; + } + opt_dirty_max <<= prefix_arg; + if (opt_dirty_max == 0) { + // If the shift above overflowed all the bits then clamp the result + // instead. If we started with DIRTY_MAX_DEFAULT then this will + // always be a power of two so choose the maximum power of two that + // fits in a size_t. + opt_dirty_max = size_t(1) << (sizeof(size_t) * CHAR_BIT - 1); + } + break; +#ifdef MALLOC_RUNTIME_CONFIG + case 'j': + opt_junk = false; + break; + case 'J': + opt_junk = true; + break; + case 'q': + // The argument selects how much poisoning to do. + opt_poison = NONE; + break; + case 'Q': + if (opts[i + 1] == 'Q') { + // Maximum poisoning. + i++; + opt_poison = ALL; + } else { + opt_poison = SOME; + opt_poison_size = kCacheLineSize * prefix_arg; + } + break; + case 'z': + opt_zero = false; + break; + case 'Z': + opt_zero = true; + break; +# ifndef MALLOC_STATIC_PAGESIZE + case 'P': + MOZ_ASSERT(gPageSize >= 4_KiB); + MOZ_ASSERT(gPageSize <= 64_KiB); + prefix_arg = prefix_arg ? prefix_arg : 1; + gPageSize <<= prefix_arg; + // We know that if the shift causes gPageSize to be zero then it's + // because it shifted all the bits off. We didn't start with zero. + // Therefore if gPageSize is out of bounds we set it to 64KiB. + if (gPageSize < 4_KiB || gPageSize > 64_KiB) { + gPageSize = 64_KiB; + } + break; +# endif +#endif + case 'r': + opt_randomize_small = false; + break; + case 'R': + opt_randomize_small = true; + break; + default: { + char cbuf[2]; + + cbuf[0] = opts[i]; + cbuf[1] = '\0'; + _malloc_message(_getprogname(), + ": (malloc) Unsupported character " + "in malloc options: '", + cbuf, "'\n"); + } + } + } + } + +#ifndef MALLOC_STATIC_PAGESIZE + DefineGlobals(); +#endif + gRecycledSize = 0; + + // Initialize chunks data. + chunks_mtx.Init(); + MOZ_PUSH_IGNORE_THREAD_SAFETY + gChunksBySize.Init(); + gChunksByAddress.Init(); + MOZ_POP_THREAD_SAFETY + + // Initialize huge allocation data. + huge_mtx.Init(); + MOZ_PUSH_IGNORE_THREAD_SAFETY + huge.Init(); + huge_allocated = 0; + huge_mapped = 0; + MOZ_POP_THREAD_SAFETY + + // Initialize base allocation data structures. + base_mtx.Init(); + MOZ_PUSH_IGNORE_THREAD_SAFETY + base_mapped = 0; + base_committed = 0; + MOZ_POP_THREAD_SAFETY + + // Initialize arenas collection here. + if (!gArenas.Init()) { + return false; + } + + // Assign the default arena to the initial thread. + thread_arena.set(gArenas.GetDefault()); + + if (!gChunkRTree.Init()) { + return false; + } + + malloc_initialized = true; + + // Dummy call so that the function is not removed by dead-code elimination + Debug::jemalloc_ptr_info(nullptr); + +#if !defined(XP_WIN) && !defined(XP_DARWIN) + // Prevent potential deadlock on malloc locks after fork. + pthread_atfork(_malloc_prefork, _malloc_postfork_parent, + _malloc_postfork_child); +#endif + + return true; +} + +// End general internal functions. +// *************************************************************************** +// Begin malloc(3)-compatible functions. + +// The BaseAllocator class is a helper class that implements the base allocator +// functions (malloc, calloc, realloc, free, memalign) for a given arena, +// or an appropriately chosen arena (per choose_arena()) when none is given. +struct BaseAllocator { +#define MALLOC_DECL(name, return_type, ...) \ + inline return_type name(__VA_ARGS__); + +#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC_BASE +#include "malloc_decls.h" + + explicit BaseAllocator(arena_t* aArena) : mArena(aArena) {} + + private: + arena_t* mArena; +}; + +#define MALLOC_DECL(name, return_type, ...) \ + inline return_type MozJemalloc::name( \ + ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) { \ + BaseAllocator allocator(nullptr); \ + return allocator.name(ARGS_HELPER(ARGS, ##__VA_ARGS__)); \ + } +#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC_BASE +#include "malloc_decls.h" + +inline void* BaseAllocator::malloc(size_t aSize) { + void* ret; + arena_t* arena; + + if (!malloc_init()) { + ret = nullptr; + goto RETURN; + } + + if (aSize == 0) { + aSize = 1; + } + // If mArena is non-null, it must not be in the first page. + MOZ_DIAGNOSTIC_ASSERT_IF(mArena, (size_t)mArena >= gPageSize); + arena = mArena ? mArena : choose_arena(aSize); + ret = arena->Malloc(aSize, /* aZero = */ false); + +RETURN: + if (!ret) { + errno = ENOMEM; + } + + return ret; +} + +inline void* BaseAllocator::memalign(size_t aAlignment, size_t aSize) { + MOZ_ASSERT(((aAlignment - 1) & aAlignment) == 0); + + if (!malloc_init()) { + return nullptr; + } + + if (aSize == 0) { + aSize = 1; + } + + aAlignment = aAlignment < sizeof(void*) ? sizeof(void*) : aAlignment; + arena_t* arena = mArena ? mArena : choose_arena(aSize); + return arena->Palloc(aAlignment, aSize); +} + +inline void* BaseAllocator::calloc(size_t aNum, size_t aSize) { + void* ret; + + if (malloc_init()) { + CheckedInt<size_t> checkedSize = CheckedInt<size_t>(aNum) * aSize; + if (checkedSize.isValid()) { + size_t allocSize = checkedSize.value(); + if (allocSize == 0) { + allocSize = 1; + } + arena_t* arena = mArena ? mArena : choose_arena(allocSize); + ret = arena->Malloc(allocSize, /* aZero = */ true); + } else { + ret = nullptr; + } + } else { + ret = nullptr; + } + + if (!ret) { + errno = ENOMEM; + } + + return ret; +} + +inline void* BaseAllocator::realloc(void* aPtr, size_t aSize) { + void* ret; + + if (aSize == 0) { + aSize = 1; + } + + if (aPtr) { + MOZ_RELEASE_ASSERT(malloc_initialized); + + auto info = AllocInfo::Get(aPtr); + auto arena = info.Arena(); + MOZ_RELEASE_ASSERT(!mArena || arena == mArena); + ret = arena->Ralloc(aPtr, aSize, info.Size()); + } else { + if (!malloc_init()) { + ret = nullptr; + } else { + arena_t* arena = mArena ? mArena : choose_arena(aSize); + ret = arena->Malloc(aSize, /* aZero = */ false); + } + } + + if (!ret) { + errno = ENOMEM; + } + return ret; +} + +inline void BaseAllocator::free(void* aPtr) { + size_t offset; + + // A version of idalloc that checks for nullptr pointer. + offset = GetChunkOffsetForPtr(aPtr); + if (offset != 0) { + MOZ_RELEASE_ASSERT(malloc_initialized); + arena_dalloc(aPtr, offset, mArena); + } else if (aPtr) { + MOZ_RELEASE_ASSERT(malloc_initialized); + huge_dalloc(aPtr, mArena); + } +} + +inline int MozJemalloc::posix_memalign(void** aMemPtr, size_t aAlignment, + size_t aSize) { + return AlignedAllocator<memalign>::posix_memalign(aMemPtr, aAlignment, aSize); +} + +inline void* MozJemalloc::aligned_alloc(size_t aAlignment, size_t aSize) { + return AlignedAllocator<memalign>::aligned_alloc(aAlignment, aSize); +} + +inline void* MozJemalloc::valloc(size_t aSize) { + return AlignedAllocator<memalign>::valloc(aSize); +} + +// End malloc(3)-compatible functions. +// *************************************************************************** +// Begin non-standard functions. + +// This was added by Mozilla for use by SQLite. +inline size_t MozJemalloc::malloc_good_size(size_t aSize) { + if (aSize <= gMaxLargeClass) { + // Small or large + aSize = SizeClass(aSize).Size(); + } else { + // Huge. We use PAGE_CEILING to get psize, instead of using + // CHUNK_CEILING to get csize. This ensures that this + // malloc_usable_size(malloc(n)) always matches + // malloc_good_size(n). + aSize = PAGE_CEILING(aSize); + } + return aSize; +} + +inline size_t MozJemalloc::malloc_usable_size(usable_ptr_t aPtr) { + return AllocInfo::GetValidated(aPtr).Size(); +} + +inline void MozJemalloc::jemalloc_stats_internal( + jemalloc_stats_t* aStats, jemalloc_bin_stats_t* aBinStats) { + size_t non_arena_mapped, chunk_header_size; + + if (!aStats) { + return; + } + if (!malloc_init()) { + memset(aStats, 0, sizeof(*aStats)); + return; + } + if (aBinStats) { + memset(aBinStats, 0, sizeof(jemalloc_bin_stats_t) * NUM_SMALL_CLASSES); + } + + // Gather runtime settings. + aStats->opt_junk = opt_junk; + aStats->opt_zero = opt_zero; + aStats->quantum = kQuantum; + aStats->quantum_max = kMaxQuantumClass; + aStats->quantum_wide = kQuantumWide; + aStats->quantum_wide_max = kMaxQuantumWideClass; + aStats->subpage_max = gMaxSubPageClass; + aStats->large_max = gMaxLargeClass; + aStats->chunksize = kChunkSize; + aStats->page_size = gPageSize; + aStats->dirty_max = opt_dirty_max; + + // Gather current memory usage statistics. + aStats->narenas = 0; + aStats->mapped = 0; + aStats->allocated = 0; + aStats->waste = 0; + aStats->page_cache = 0; + aStats->bookkeeping = 0; + aStats->bin_unused = 0; + + non_arena_mapped = 0; + + // Get huge mapped/allocated. + { + MutexAutoLock lock(huge_mtx); + non_arena_mapped += huge_mapped; + aStats->allocated += huge_allocated; + MOZ_ASSERT(huge_mapped >= huge_allocated); + } + + // Get base mapped/allocated. + { + MutexAutoLock lock(base_mtx); + non_arena_mapped += base_mapped; + aStats->bookkeeping += base_committed; + MOZ_ASSERT(base_mapped >= base_committed); + } + + gArenas.mLock.Lock(); + + // Stats can only read complete information if its run on the main thread. + MOZ_ASSERT(gArenas.IsOnMainThreadWeak()); + + // Iterate over arenas. + for (auto arena : gArenas.iter()) { + // Cannot safely read stats for this arena and therefore stats would be + // incomplete. + MOZ_ASSERT(arena->mLock.SafeOnThisThread()); + + size_t arena_mapped, arena_allocated, arena_committed, arena_dirty, j, + arena_unused, arena_headers; + + arena_headers = 0; + arena_unused = 0; + + { + MaybeMutexAutoLock lock(arena->mLock); + + arena_mapped = arena->mStats.mapped; + + // "committed" counts dirty and allocated memory. + arena_committed = arena->mStats.committed << gPageSize2Pow; + + arena_allocated = + arena->mStats.allocated_small + arena->mStats.allocated_large; + + arena_dirty = arena->mNumDirty << gPageSize2Pow; + + for (j = 0; j < NUM_SMALL_CLASSES; j++) { + arena_bin_t* bin = &arena->mBins[j]; + size_t bin_unused = 0; + size_t num_non_full_runs = 0; + + for (auto mapelm : bin->mNonFullRuns.iter()) { + arena_run_t* run = (arena_run_t*)(mapelm->bits & ~gPageSizeMask); + bin_unused += run->mNumFree * bin->mSizeClass; + num_non_full_runs++; + } + + if (bin->mCurrentRun) { + bin_unused += bin->mCurrentRun->mNumFree * bin->mSizeClass; + num_non_full_runs++; + } + + arena_unused += bin_unused; + arena_headers += bin->mNumRuns * bin->mRunFirstRegionOffset; + if (aBinStats) { + aBinStats[j].size = bin->mSizeClass; + aBinStats[j].num_non_full_runs += num_non_full_runs; + aBinStats[j].num_runs += bin->mNumRuns; + aBinStats[j].bytes_unused += bin_unused; + size_t bytes_per_run = static_cast<size_t>(bin->mRunSizePages) + << gPageSize2Pow; + aBinStats[j].bytes_total += + bin->mNumRuns * (bytes_per_run - bin->mRunFirstRegionOffset); + aBinStats[j].bytes_per_run = bytes_per_run; + } + } + } + + MOZ_ASSERT(arena_mapped >= arena_committed); + MOZ_ASSERT(arena_committed >= arena_allocated + arena_dirty); + + aStats->mapped += arena_mapped; + aStats->allocated += arena_allocated; + aStats->page_cache += arena_dirty; + // "waste" is committed memory that is neither dirty nor + // allocated. If you change this definition please update + // memory/replace/logalloc/replay/Replay.cpp's jemalloc_stats calculation of + // committed. + MOZ_ASSERT(arena_committed >= + (arena_allocated + arena_dirty + arena_unused + arena_headers)); + aStats->waste += arena_committed - arena_allocated - arena_dirty - + arena_unused - arena_headers; + aStats->bin_unused += arena_unused; + aStats->bookkeeping += arena_headers; + aStats->narenas++; + } + gArenas.mLock.Unlock(); + + // Account for arena chunk headers in bookkeeping rather than waste. + chunk_header_size = + ((aStats->mapped / aStats->chunksize) * (gChunkHeaderNumPages - 1)) + << gPageSize2Pow; + + aStats->mapped += non_arena_mapped; + aStats->bookkeeping += chunk_header_size; + aStats->waste -= chunk_header_size; + + MOZ_ASSERT(aStats->mapped >= aStats->allocated + aStats->waste + + aStats->page_cache + aStats->bookkeeping); +} + +inline size_t MozJemalloc::jemalloc_stats_num_bins() { + return NUM_SMALL_CLASSES; +} + +inline void MozJemalloc::jemalloc_set_main_thread() { + MOZ_ASSERT(malloc_initialized); + gArenas.SetMainThread(); +} + +#ifdef MALLOC_DOUBLE_PURGE + +// Explicitly remove all of this chunk's MADV_FREE'd pages from memory. +static void hard_purge_chunk(arena_chunk_t* aChunk) { + // See similar logic in arena_t::Purge(). + for (size_t i = gChunkHeaderNumPages; i < gChunkNumPages; i++) { + // Find all adjacent pages with CHUNK_MAP_MADVISED set. + size_t npages; + for (npages = 0; aChunk->map[i + npages].bits & CHUNK_MAP_MADVISED && + i + npages < gChunkNumPages; + npages++) { + // Turn off the chunk's MADV_FREED bit and turn on its + // DECOMMITTED bit. + MOZ_DIAGNOSTIC_ASSERT( + !(aChunk->map[i + npages].bits & CHUNK_MAP_DECOMMITTED)); + aChunk->map[i + npages].bits ^= CHUNK_MAP_MADVISED_OR_DECOMMITTED; + } + + // We could use mincore to find out which pages are actually + // present, but it's not clear that's better. + if (npages > 0) { + pages_decommit(((char*)aChunk) + (i << gPageSize2Pow), + npages << gPageSize2Pow); + Unused << pages_commit(((char*)aChunk) + (i << gPageSize2Pow), + npages << gPageSize2Pow); + } + i += npages; + } +} + +// Explicitly remove all of this arena's MADV_FREE'd pages from memory. +void arena_t::HardPurge() { + MaybeMutexAutoLock lock(mLock); + + while (!mChunksMAdvised.isEmpty()) { + arena_chunk_t* chunk = mChunksMAdvised.popFront(); + hard_purge_chunk(chunk); + } +} + +inline void MozJemalloc::jemalloc_purge_freed_pages() { + if (malloc_initialized) { + MutexAutoLock lock(gArenas.mLock); + MOZ_ASSERT(gArenas.IsOnMainThreadWeak()); + for (auto arena : gArenas.iter()) { + arena->HardPurge(); + } + } +} + +#else // !defined MALLOC_DOUBLE_PURGE + +inline void MozJemalloc::jemalloc_purge_freed_pages() { + // Do nothing. +} + +#endif // defined MALLOC_DOUBLE_PURGE + +inline void MozJemalloc::jemalloc_free_dirty_pages(void) { + if (malloc_initialized) { + MutexAutoLock lock(gArenas.mLock); + MOZ_ASSERT(gArenas.IsOnMainThreadWeak()); + for (auto arena : gArenas.iter()) { + MaybeMutexAutoLock arena_lock(arena->mLock); + arena->Purge(1); + } + } +} + +inline arena_t* ArenaCollection::GetByIdInternal(Tree& aTree, + arena_id_t aArenaId) { + // Use AlignedStorage2 to avoid running the arena_t constructor, while + // we only need it as a placeholder for mId. + mozilla::AlignedStorage2<arena_t> key; + key.addr()->mId = aArenaId; + return aTree.Search(key.addr()); +} + +inline arena_t* ArenaCollection::GetById(arena_id_t aArenaId, bool aIsPrivate) { + if (!malloc_initialized) { + return nullptr; + } + + Tree* tree = nullptr; + if (aIsPrivate) { + if (ArenaIdIsMainThreadOnly(aArenaId)) { + // Main thread only arena. Do the lookup here without taking the lock. + arena_t* result = GetByIdInternal(mMainThreadArenas, aArenaId); + MOZ_RELEASE_ASSERT(result); + return result; + } + tree = &mPrivateArenas; + } else { + tree = &mArenas; + } + + MutexAutoLock lock(mLock); + arena_t* result = GetByIdInternal(*tree, aArenaId); + MOZ_RELEASE_ASSERT(result); + return result; +} + +inline arena_id_t MozJemalloc::moz_create_arena_with_params( + arena_params_t* aParams) { + if (malloc_init()) { + arena_t* arena = gArenas.CreateArena(/* IsPrivate = */ true, aParams); + return arena->mId; + } + return 0; +} + +inline void MozJemalloc::moz_dispose_arena(arena_id_t aArenaId) { + arena_t* arena = gArenas.GetById(aArenaId, /* IsPrivate = */ true); + MOZ_RELEASE_ASSERT(arena); + gArenas.DisposeArena(arena); +} + +inline void MozJemalloc::moz_set_max_dirty_page_modifier(int32_t aModifier) { + gArenas.SetDefaultMaxDirtyPageModifier(aModifier); +} + +#define MALLOC_DECL(name, return_type, ...) \ + inline return_type MozJemalloc::moz_arena_##name( \ + arena_id_t aArenaId, ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) { \ + BaseAllocator allocator( \ + gArenas.GetById(aArenaId, /* IsPrivate = */ true)); \ + return allocator.name(ARGS_HELPER(ARGS, ##__VA_ARGS__)); \ + } +#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC_BASE +#include "malloc_decls.h" + +// End non-standard functions. +// *************************************************************************** +#ifndef XP_WIN +// Begin library-private functions, used by threading libraries for protection +// of malloc during fork(). These functions are only called if the program is +// running in threaded mode, so there is no need to check whether the program +// is threaded here. +// +// Note that the only way to keep the main-thread-only arenas in a consistent +// state for the child is if fork is called from the main thread only. Or the +// child must not use them, eg it should call exec(). We attempt to prevent the +// child for accessing these arenas by refusing to re-initialise them. +static pthread_t gForkingThread; + +FORK_HOOK +void _malloc_prefork(void) MOZ_NO_THREAD_SAFETY_ANALYSIS { + // Acquire all mutexes in a safe order. + gArenas.mLock.Lock(); + gForkingThread = pthread_self(); + + for (auto arena : gArenas.iter()) { + if (arena->mLock.LockIsEnabled()) { + arena->mLock.Lock(); + } + } + + base_mtx.Lock(); + + huge_mtx.Lock(); +} + +FORK_HOOK +void _malloc_postfork_parent(void) MOZ_NO_THREAD_SAFETY_ANALYSIS { + // Release all mutexes, now that fork() has completed. + huge_mtx.Unlock(); + + base_mtx.Unlock(); + + for (auto arena : gArenas.iter()) { + if (arena->mLock.LockIsEnabled()) { + arena->mLock.Unlock(); + } + } + + gArenas.mLock.Unlock(); +} + +FORK_HOOK +void _malloc_postfork_child(void) { + // Reinitialize all mutexes, now that fork() has completed. + huge_mtx.Init(); + + base_mtx.Init(); + + for (auto arena : gArenas.iter()) { + arena->mLock.Reinit(gForkingThread); + } + + gArenas.PostForkFixMainThread(); + gArenas.mLock.Init(); +} +#endif // XP_WIN + +// End library-private functions. +// *************************************************************************** +#ifdef MOZ_REPLACE_MALLOC +// Windows doesn't come with weak imports as they are possible with +// LD_PRELOAD or DYLD_INSERT_LIBRARIES on Linux/OSX. On this platform, +// the replacement functions are defined as variable pointers to the +// function resolved with GetProcAddress() instead of weak definitions +// of functions. On Android, the same needs to happen as well, because +// the Android linker doesn't handle weak linking with non LD_PRELOADed +// libraries, but LD_PRELOADing is not very convenient on Android, with +// the zygote. +# ifdef XP_DARWIN +# define MOZ_REPLACE_WEAK __attribute__((weak_import)) +# elif defined(XP_WIN) || defined(ANDROID) +# define MOZ_DYNAMIC_REPLACE_INIT +# define replace_init replace_init_decl +# elif defined(__GNUC__) +# define MOZ_REPLACE_WEAK __attribute__((weak)) +# endif + +# include "replace_malloc.h" + +# define MALLOC_DECL(name, return_type, ...) CanonicalMalloc::name, + +// The default malloc table, i.e. plain allocations. It never changes. It's +// used by init(), and not used after that. +static const malloc_table_t gDefaultMallocTable = { +# include "malloc_decls.h" +}; + +// The malloc table installed by init(). It never changes from that point +// onward. It will be the same as gDefaultMallocTable if no replace-malloc tool +// is enabled at startup. +static malloc_table_t gOriginalMallocTable = { +# include "malloc_decls.h" +}; + +// The malloc table installed by jemalloc_replace_dynamic(). (Read the +// comments above that function for more details.) +static malloc_table_t gDynamicMallocTable = { +# include "malloc_decls.h" +}; + +// This briefly points to gDefaultMallocTable at startup. After that, it points +// to either gOriginalMallocTable or gDynamicMallocTable. It's atomic to avoid +// races when switching between tables. +static Atomic<malloc_table_t const*, mozilla::MemoryOrdering::Relaxed> + gMallocTablePtr; + +# ifdef MOZ_DYNAMIC_REPLACE_INIT +# undef replace_init +typedef decltype(replace_init_decl) replace_init_impl_t; +static replace_init_impl_t* replace_init = nullptr; +# endif + +# ifdef XP_WIN +typedef HMODULE replace_malloc_handle_t; + +static replace_malloc_handle_t replace_malloc_handle() { + wchar_t replace_malloc_lib[1024]; + if (GetEnvironmentVariableW(L"MOZ_REPLACE_MALLOC_LIB", replace_malloc_lib, + ArrayLength(replace_malloc_lib)) > 0) { + return LoadLibraryW(replace_malloc_lib); + } + return nullptr; +} + +# define REPLACE_MALLOC_GET_INIT_FUNC(handle) \ + (replace_init_impl_t*)GetProcAddress(handle, "replace_init") + +# elif defined(ANDROID) +# include <dlfcn.h> + +typedef void* replace_malloc_handle_t; + +static replace_malloc_handle_t replace_malloc_handle() { + const char* replace_malloc_lib = getenv("MOZ_REPLACE_MALLOC_LIB"); + if (replace_malloc_lib && *replace_malloc_lib) { + return dlopen(replace_malloc_lib, RTLD_LAZY); + } + return nullptr; +} + +# define REPLACE_MALLOC_GET_INIT_FUNC(handle) \ + (replace_init_impl_t*)dlsym(handle, "replace_init") + +# endif + +static void replace_malloc_init_funcs(malloc_table_t*); + +# ifdef MOZ_REPLACE_MALLOC_STATIC +extern "C" void logalloc_init(malloc_table_t*, ReplaceMallocBridge**); + +extern "C" void dmd_init(malloc_table_t*, ReplaceMallocBridge**); +# endif + +void phc_init(malloc_table_t*, ReplaceMallocBridge**); + +bool Equals(const malloc_table_t& aTable1, const malloc_table_t& aTable2) { + return memcmp(&aTable1, &aTable2, sizeof(malloc_table_t)) == 0; +} + +// Below is the malloc implementation overriding jemalloc and calling the +// replacement functions if they exist. +static ReplaceMallocBridge* gReplaceMallocBridge = nullptr; +static void init() { + malloc_table_t tempTable = gDefaultMallocTable; + +# ifdef MOZ_DYNAMIC_REPLACE_INIT + replace_malloc_handle_t handle = replace_malloc_handle(); + if (handle) { + replace_init = REPLACE_MALLOC_GET_INIT_FUNC(handle); + } +# endif + + // Set this *before* calling replace_init, otherwise if replace_init calls + // malloc() we'll get an infinite loop. + gMallocTablePtr = &gDefaultMallocTable; + + // Pass in the default allocator table so replace functions can copy and use + // it for their allocations. The replace_init() function should modify the + // table if it wants to be active, otherwise leave it unmodified. + if (replace_init) { + replace_init(&tempTable, &gReplaceMallocBridge); + } +# ifdef MOZ_REPLACE_MALLOC_STATIC + if (Equals(tempTable, gDefaultMallocTable)) { + logalloc_init(&tempTable, &gReplaceMallocBridge); + } +# ifdef MOZ_DMD + if (Equals(tempTable, gDefaultMallocTable)) { + dmd_init(&tempTable, &gReplaceMallocBridge); + } +# endif +# endif + if (!Equals(tempTable, gDefaultMallocTable)) { + replace_malloc_init_funcs(&tempTable); + } + gOriginalMallocTable = tempTable; + gMallocTablePtr = &gOriginalMallocTable; +} + +// WARNING WARNING WARNING: this function should be used with extreme care. It +// is not as general-purpose as it looks. It is currently used by +// tools/profiler/core/memory_hooks.cpp for counting allocations and probably +// should not be used for any other purpose. +// +// This function allows the original malloc table to be temporarily replaced by +// a different malloc table. Or, if the argument is nullptr, it switches back to +// the original malloc table. +// +// Limitations: +// +// - It is not threadsafe. If multiple threads pass it the same +// `replace_init_func` at the same time, there will be data races writing to +// the malloc_table_t within that function. +// +// - Only one replacement can be installed. No nesting is allowed. +// +// - The new malloc table must be able to free allocations made by the original +// malloc table, and upon removal the original malloc table must be able to +// free allocations made by the new malloc table. This means the new malloc +// table can only do simple things like recording extra information, while +// delegating actual allocation/free operations to the original malloc table. +// +MOZ_JEMALLOC_API void jemalloc_replace_dynamic( + jemalloc_init_func replace_init_func) { + if (replace_init_func) { + malloc_table_t tempTable = gOriginalMallocTable; + (*replace_init_func)(&tempTable, &gReplaceMallocBridge); + if (!Equals(tempTable, gOriginalMallocTable)) { + replace_malloc_init_funcs(&tempTable); + + // Temporarily switch back to the original malloc table. In the + // (supported) non-nested case, this is a no-op. But just in case this is + // a (unsupported) nested call, it makes the overwriting of + // gDynamicMallocTable less racy, because ongoing calls to malloc() and + // friends won't go through gDynamicMallocTable. + gMallocTablePtr = &gOriginalMallocTable; + + gDynamicMallocTable = tempTable; + gMallocTablePtr = &gDynamicMallocTable; + // We assume that dynamic replaces don't occur close enough for a + // thread to still have old copies of the table pointer when the 2nd + // replace occurs. + } + } else { + // Switch back to the original malloc table. + gMallocTablePtr = &gOriginalMallocTable; + } +} + +# define MALLOC_DECL(name, return_type, ...) \ + inline return_type ReplaceMalloc::name( \ + ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) { \ + if (MOZ_UNLIKELY(!gMallocTablePtr)) { \ + init(); \ + } \ + return (*gMallocTablePtr).name(ARGS_HELPER(ARGS, ##__VA_ARGS__)); \ + } +# include "malloc_decls.h" + +MOZ_JEMALLOC_API struct ReplaceMallocBridge* get_bridge(void) { + if (MOZ_UNLIKELY(!gMallocTablePtr)) { + init(); + } + return gReplaceMallocBridge; +} + +// posix_memalign, aligned_alloc, memalign and valloc all implement some kind +// of aligned memory allocation. For convenience, a replace-malloc library can +// skip defining replace_posix_memalign, replace_aligned_alloc and +// replace_valloc, and default implementations will be automatically derived +// from replace_memalign. +static void replace_malloc_init_funcs(malloc_table_t* table) { + if (table->posix_memalign == CanonicalMalloc::posix_memalign && + table->memalign != CanonicalMalloc::memalign) { + table->posix_memalign = + AlignedAllocator<ReplaceMalloc::memalign>::posix_memalign; + } + if (table->aligned_alloc == CanonicalMalloc::aligned_alloc && + table->memalign != CanonicalMalloc::memalign) { + table->aligned_alloc = + AlignedAllocator<ReplaceMalloc::memalign>::aligned_alloc; + } + if (table->valloc == CanonicalMalloc::valloc && + table->memalign != CanonicalMalloc::memalign) { + table->valloc = AlignedAllocator<ReplaceMalloc::memalign>::valloc; + } + if (table->moz_create_arena_with_params == + CanonicalMalloc::moz_create_arena_with_params && + table->malloc != CanonicalMalloc::malloc) { +# define MALLOC_DECL(name, ...) \ + table->name = DummyArenaAllocator<ReplaceMalloc>::name; +# define MALLOC_FUNCS MALLOC_FUNCS_ARENA_BASE +# include "malloc_decls.h" + } + if (table->moz_arena_malloc == CanonicalMalloc::moz_arena_malloc && + table->malloc != CanonicalMalloc::malloc) { +# define MALLOC_DECL(name, ...) \ + table->name = DummyArenaAllocator<ReplaceMalloc>::name; +# define MALLOC_FUNCS MALLOC_FUNCS_ARENA_ALLOC +# include "malloc_decls.h" + } +} + +#endif // MOZ_REPLACE_MALLOC +// *************************************************************************** +// Definition of all the _impl functions +// GENERIC_MALLOC_DECL2_MINGW is only used for the MinGW build, and aliases +// the malloc funcs (e.g. malloc) to the je_ versions. It does not generate +// aliases for the other functions (jemalloc and arena functions). +// +// We do need aliases for the other mozglue.def-redirected functions though, +// these are done at the bottom of mozmemory_wrap.cpp +#define GENERIC_MALLOC_DECL2_MINGW(name, name_impl, return_type, ...) \ + return_type name(ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) \ + __attribute__((alias(MOZ_STRINGIFY(name_impl)))); + +#define GENERIC_MALLOC_DECL2(attributes, name, name_impl, return_type, ...) \ + return_type name_impl(ARGS_HELPER(TYPED_ARGS, ##__VA_ARGS__)) attributes { \ + return DefaultMalloc::name(ARGS_HELPER(ARGS, ##__VA_ARGS__)); \ + } + +#ifndef __MINGW32__ +# define GENERIC_MALLOC_DECL(attributes, name, return_type, ...) \ + GENERIC_MALLOC_DECL2(attributes, name, name##_impl, return_type, \ + ##__VA_ARGS__) +#else +# define GENERIC_MALLOC_DECL(attributes, name, return_type, ...) \ + GENERIC_MALLOC_DECL2(attributes, name, name##_impl, return_type, \ + ##__VA_ARGS__) \ + GENERIC_MALLOC_DECL2_MINGW(name, name##_impl, return_type, ##__VA_ARGS__) +#endif + +#define NOTHROW_MALLOC_DECL(...) \ + MOZ_MEMORY_API MACRO_CALL(GENERIC_MALLOC_DECL, (noexcept(true), __VA_ARGS__)) +#define MALLOC_DECL(...) \ + MOZ_MEMORY_API MACRO_CALL(GENERIC_MALLOC_DECL, (, __VA_ARGS__)) +#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC +#include "malloc_decls.h" + +#undef GENERIC_MALLOC_DECL +#define GENERIC_MALLOC_DECL(attributes, name, return_type, ...) \ + GENERIC_MALLOC_DECL2(attributes, name, name, return_type, ##__VA_ARGS__) + +#define MALLOC_DECL(...) \ + MOZ_JEMALLOC_API MACRO_CALL(GENERIC_MALLOC_DECL, (, __VA_ARGS__)) +#define MALLOC_FUNCS (MALLOC_FUNCS_JEMALLOC | MALLOC_FUNCS_ARENA) +#include "malloc_decls.h" +// *************************************************************************** + +#ifdef HAVE_DLOPEN +# include <dlfcn.h> +#endif + +#if defined(__GLIBC__) && !defined(__UCLIBC__) +// glibc provides the RTLD_DEEPBIND flag for dlopen which can make it possible +// to inconsistently reference libc's malloc(3)-compatible functions +// (bug 493541). +// +// These definitions interpose hooks in glibc. The functions are actually +// passed an extra argument for the caller return address, which will be +// ignored. + +extern "C" { +MOZ_EXPORT void (*__free_hook)(void*) = free_impl; +MOZ_EXPORT void* (*__malloc_hook)(size_t) = malloc_impl; +MOZ_EXPORT void* (*__realloc_hook)(void*, size_t) = realloc_impl; +MOZ_EXPORT void* (*__memalign_hook)(size_t, size_t) = memalign_impl; +} + +#elif defined(RTLD_DEEPBIND) +// XXX On systems that support RTLD_GROUP or DF_1_GROUP, do their +// implementations permit similar inconsistencies? Should STV_SINGLETON +// visibility be used for interposition where available? +# error \ + "Interposing malloc is unsafe on this system without libc malloc hooks." +#endif + +#ifdef XP_WIN +MOZ_EXPORT void* _recalloc(void* aPtr, size_t aCount, size_t aSize) { + size_t oldsize = aPtr ? AllocInfo::Get(aPtr).Size() : 0; + CheckedInt<size_t> checkedSize = CheckedInt<size_t>(aCount) * aSize; + + if (!checkedSize.isValid()) { + return nullptr; + } + + size_t newsize = checkedSize.value(); + + // In order for all trailing bytes to be zeroed, the caller needs to + // use calloc(), followed by recalloc(). However, the current calloc() + // implementation only zeros the bytes requested, so if recalloc() is + // to work 100% correctly, calloc() will need to change to zero + // trailing bytes. + aPtr = DefaultMalloc::realloc(aPtr, newsize); + if (aPtr && oldsize < newsize) { + memset((void*)((uintptr_t)aPtr + oldsize), 0, newsize - oldsize); + } + + return aPtr; +} + +// This impl of _expand doesn't ever actually expand or shrink blocks: it +// simply replies that you may continue using a shrunk block. +MOZ_EXPORT void* _expand(void* aPtr, size_t newsize) { + if (AllocInfo::Get(aPtr).Size() >= newsize) { + return aPtr; + } + + return nullptr; +} + +MOZ_EXPORT size_t _msize(void* aPtr) { + return DefaultMalloc::malloc_usable_size(aPtr); +} +#endif + +#ifdef MOZ_PHC +// Compile PHC and mozjemalloc together so that PHC can inline mozjemalloc. +# include "PHC.cpp" +#endif |