| File: | var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp |
| Warning: | line 504, column 7 Excessive padding in 'class PHC' (80 padding bytes, where 16 is optimal). Optimal fields order: mAvgFirstAllocDelay, mPhcState, mNow, mRNG, mFreePageListHead, mFreePageListTail, mMutex, mAllocPages, mAvgAllocDelay, mAvgPageReuseDelay, consider reordering the fields or adding explicit padding members |
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| 1 | /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| 2 | /* vim: set ts=8 sts=2 et sw=2 tw=80: */ |
| 3 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| 4 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| 5 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| 6 | |
| 7 | // PHC is a probabilistic heap checker. A tiny fraction of randomly chosen heap |
| 8 | // allocations are subject to some expensive checking via the use of OS page |
| 9 | // access protection. A failed check triggers a crash, whereupon useful |
| 10 | // information about the failure is put into the crash report. The cost and |
| 11 | // coverage for each user is minimal, but spread over the entire user base the |
| 12 | // coverage becomes significant. |
| 13 | // |
| 14 | // The idea comes from Chromium, where it is called GWP-ASAN. (Firefox uses PHC |
| 15 | // as the name because GWP-ASAN is long, awkward, and doesn't have any |
| 16 | // particular meaning.) |
| 17 | // |
| 18 | // In the current implementation up to 64 allocations per process can become |
| 19 | // PHC allocations. These allocations must be page-sized or smaller. Each PHC |
| 20 | // allocation gets its own page, and when the allocation is freed its page is |
| 21 | // marked inaccessible until the page is reused for another allocation. This |
| 22 | // means that a use-after-free defect (which includes double-frees) will be |
| 23 | // caught if the use occurs before the page is reused for another allocation. |
| 24 | // The crash report will contain stack traces for the allocation site, the free |
| 25 | // site, and the use-after-free site, which is often enough to diagnose the |
| 26 | // defect. |
| 27 | // |
| 28 | // Also, each PHC allocation is followed by a guard page. The PHC allocation is |
| 29 | // positioned so that its end abuts the guard page (or as close as possible, |
| 30 | // given alignment constraints). This means that a bounds violation at the end |
| 31 | // of the allocation (overflow) will be caught. The crash report will contain |
| 32 | // stack traces for the allocation site and the bounds violation use site, |
| 33 | // which is often enough to diagnose the defect. |
| 34 | // |
| 35 | // (A bounds violation at the start of the allocation (underflow) will not be |
| 36 | // caught, unless it is sufficiently large to hit the preceding allocation's |
| 37 | // guard page, which is not that likely. It would be possible to look more |
| 38 | // assiduously for underflow by randomly placing some allocations at the end of |
| 39 | // the page and some at the start of the page, and GWP-ASAN does this. PHC does |
| 40 | // not, however, because overflow is likely to be much more common than |
| 41 | // underflow in practice.) |
| 42 | // |
| 43 | // We use a simple heuristic to categorize a guard page access as overflow or |
| 44 | // underflow: if the address falls in the lower half of the guard page, we |
| 45 | // assume it is overflow, otherwise we assume it is underflow. More |
| 46 | // sophisticated heuristics are possible, but this one is very simple, and it is |
| 47 | // likely that most overflows/underflows in practice are very close to the page |
| 48 | // boundary. |
| 49 | // |
| 50 | // The design space for the randomization strategy is large. The current |
| 51 | // implementation has a large random delay before it starts operating, and a |
| 52 | // small random delay between each PHC allocation attempt. Each freed PHC |
| 53 | // allocation is quarantined for a medium random delay before being reused, in |
| 54 | // order to increase the chance of catching UAFs. |
| 55 | // |
| 56 | // The basic cost of PHC's operation is as follows. |
| 57 | // |
| 58 | // - The physical memory cost is 64 pages plus some metadata (including stack |
| 59 | // traces) for each page. This amounts to 256 KiB per process on |
| 60 | // architectures with 4 KiB pages and 1024 KiB on macOS/AArch64 which uses |
| 61 | // 16 KiB pages. |
| 62 | // |
| 63 | // - The virtual memory cost is the physical memory cost plus the guard pages: |
| 64 | // another 64 pages. This amounts to another 256 KiB per process on |
| 65 | // architectures with 4 KiB pages and 1024 KiB on macOS/AArch64 which uses |
| 66 | // 16 KiB pages. PHC is currently only enabled on 64-bit platforms so the |
| 67 | // impact of the virtual memory usage is negligible. |
| 68 | // |
| 69 | // - Every allocation requires a size check and a decrement-and-check of an |
| 70 | // atomic counter. When the counter reaches zero a PHC allocation can occur, |
| 71 | // which involves marking a page as accessible and getting a stack trace for |
| 72 | // the allocation site. Otherwise, mozjemalloc performs the allocation. |
| 73 | // |
| 74 | // - Every deallocation requires a range check on the pointer to see if it |
| 75 | // involves a PHC allocation. (The choice to only do PHC allocations that are |
| 76 | // a page or smaller enables this range check, because the 64 pages are |
| 77 | // contiguous. Allowing larger allocations would make this more complicated, |
| 78 | // and we definitely don't want something as slow as a hash table lookup on |
| 79 | // every deallocation.) PHC deallocations involve marking a page as |
| 80 | // inaccessible and getting a stack trace for the deallocation site. |
| 81 | // |
| 82 | // Note that calls to realloc(), free(), and malloc_usable_size() will |
| 83 | // immediately crash if the given pointer falls within a page allocation's |
| 84 | // page, but does not point to the start of the allocation itself. |
| 85 | // |
| 86 | // void* p = malloc(64); |
| 87 | // free(p + 1); // p+1 doesn't point to the allocation start; crash |
| 88 | // |
| 89 | // Such crashes will not have the PHC fields in the crash report. |
| 90 | // |
| 91 | // PHC-specific tests can be run with the following commands: |
| 92 | // - gtests: `./mach gtest '*PHC*'` |
| 93 | // - xpcshell-tests: `./mach test toolkit/crashreporter/test/unit` |
| 94 | // - This runs some non-PHC tests as well. |
| 95 | |
| 96 | #include "PHC.h" |
| 97 | |
| 98 | #include <stdlib.h> |
| 99 | #include <time.h> |
| 100 | |
| 101 | #include <algorithm> |
| 102 | |
| 103 | #ifdef XP_WIN |
| 104 | # include <process.h> |
| 105 | #else |
| 106 | # include <sys/mman.h> |
| 107 | # include <sys/types.h> |
| 108 | # include <pthread.h> |
| 109 | # include <unistd.h> |
| 110 | #endif |
| 111 | |
| 112 | #include "mozjemalloc.h" |
| 113 | |
| 114 | #include "mozjemalloc.h" |
| 115 | #include "FdPrintf.h" |
| 116 | #include "Mutex.h" |
| 117 | #include "mozilla/Assertions.h" |
| 118 | #include "mozilla/Atomics.h" |
| 119 | #include "mozilla/Attributes.h" |
| 120 | #include "mozilla/CheckedInt.h" |
| 121 | #include "mozilla/Maybe.h" |
| 122 | #include "mozilla/StackWalk.h" |
| 123 | #include "mozilla/ThreadLocal.h" |
| 124 | #include "mozilla/XorShift128PlusRNG.h" |
| 125 | |
| 126 | using namespace mozilla; |
| 127 | |
| 128 | //--------------------------------------------------------------------------- |
| 129 | // Utilities |
| 130 | //--------------------------------------------------------------------------- |
| 131 | |
| 132 | #ifdef ANDROID |
| 133 | // Android doesn't have pthread_atfork defined in pthread.h. |
| 134 | extern "C" MOZ_EXPORT__attribute__((visibility("default"))) int pthread_atfork(void (*)(void), void (*)(void), |
| 135 | void (*)(void)); |
| 136 | #endif |
| 137 | |
| 138 | #ifndef DISALLOW_COPY_AND_ASSIGN |
| 139 | # define DISALLOW_COPY_AND_ASSIGN(T)T(const T&); void operator=(const T&) \ |
| 140 | T(const T&); \ |
| 141 | void operator=(const T&) |
| 142 | #endif |
| 143 | |
| 144 | // This class provides infallible operations for the small number of heap |
| 145 | // allocations that PHC does for itself. It would be nice if we could use the |
| 146 | // InfallibleAllocPolicy from mozalloc, but PHC cannot use mozalloc. |
| 147 | class InfallibleAllocPolicy { |
| 148 | public: |
| 149 | static void AbortOnFailure(const void* aP) { |
| 150 | if (!aP) { |
| 151 | MOZ_CRASH("PHC failed to allocate")do { do { } while (false); MOZ_ReportCrash("" "PHC failed to allocate" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 151); AnnotateMozCrashReason("MOZ_CRASH(" "PHC failed to allocate" ")"); do { *((volatile int*)__null) = 151; __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | template <class T> |
| 156 | static T* new_() { |
| 157 | void* p = MozJemalloc::malloc(sizeof(T)); |
| 158 | AbortOnFailure(p); |
| 159 | return new (p) T; |
| 160 | } |
| 161 | }; |
| 162 | |
| 163 | //--------------------------------------------------------------------------- |
| 164 | // Stack traces |
| 165 | //--------------------------------------------------------------------------- |
| 166 | |
| 167 | // This code is similar to the equivalent code within DMD. |
| 168 | |
| 169 | class StackTrace : public phc::StackTrace { |
| 170 | public: |
| 171 | StackTrace() = default; |
| 172 | |
| 173 | void Clear() { mLength = 0; } |
| 174 | |
| 175 | void Fill(); |
| 176 | |
| 177 | private: |
| 178 | static void StackWalkCallback(uint32_t aFrameNumber, void* aPc, void* aSp, |
| 179 | void* aClosure) { |
| 180 | StackTrace* st = (StackTrace*)aClosure; |
| 181 | MOZ_ASSERT(st->mLength < kMaxFrames)do { static_assert( mozilla::detail::AssertionConditionType< decltype(st->mLength < kMaxFrames)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(st->mLength < kMaxFrames ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "st->mLength < kMaxFrames", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 181); AnnotateMozCrashReason("MOZ_ASSERT" "(" "st->mLength < kMaxFrames" ")"); do { *((volatile int*)__null) = 181; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 182 | st->mPcs[st->mLength] = aPc; |
| 183 | st->mLength++; |
| 184 | MOZ_ASSERT(st->mLength == aFrameNumber)do { static_assert( mozilla::detail::AssertionConditionType< decltype(st->mLength == aFrameNumber)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(st->mLength == aFrameNumber ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "st->mLength == aFrameNumber", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 184); AnnotateMozCrashReason("MOZ_ASSERT" "(" "st->mLength == aFrameNumber" ")"); do { *((volatile int*)__null) = 184; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 185 | } |
| 186 | }; |
| 187 | |
| 188 | // WARNING WARNING WARNING: this function must only be called when PHC::mMutex |
| 189 | // is *not* locked, otherwise we might get deadlocks. |
| 190 | // |
| 191 | // How? On Windows, MozStackWalk() can lock a mutex, M, from the shared library |
| 192 | // loader. Another thread might call malloc() while holding M locked (when |
| 193 | // loading a shared library) and try to lock PHC::mMutex, causing a deadlock. |
| 194 | // So PHC::mMutex can't be locked during the call to MozStackWalk(). (For |
| 195 | // details, see https://bugzilla.mozilla.org/show_bug.cgi?id=374829#c8. On |
| 196 | // Linux, something similar can happen; see bug 824340. So we just disallow it |
| 197 | // on all platforms.) |
| 198 | // |
| 199 | // In DMD, to avoid this problem we temporarily unlock the equivalent mutex for |
| 200 | // the MozStackWalk() call. But that's grotty, and things are a bit different |
| 201 | // here, so we just require that stack traces be obtained before locking |
| 202 | // PHC::mMutex. |
| 203 | // |
| 204 | // Unfortunately, there is no reliable way at compile-time or run-time to ensure |
| 205 | // this pre-condition. Hence this large comment. |
| 206 | // |
| 207 | void StackTrace::Fill() { |
| 208 | mLength = 0; |
| 209 | |
| 210 | // These ifdefs should be kept in sync with the conditions in |
| 211 | // phc_implies_frame_pointers in build/moz.configure/memory.configure |
| 212 | #if defined(XP_WIN) && defined(_M_IX86) |
| 213 | // This avoids MozStackWalk(), which causes unusably slow startup on Win32 |
| 214 | // when it is called during static initialization (see bug 1241684). |
| 215 | // |
| 216 | // This code is cribbed from the Gecko Profiler, which also uses |
| 217 | // FramePointerStackWalk() on Win32: Registers::SyncPopulate() for the |
| 218 | // frame pointer, and GetStackTop() for the stack end. |
| 219 | CONTEXT context; |
| 220 | RtlCaptureContext(&context); |
| 221 | void** fp = reinterpret_cast<void**>(context.Ebp); |
| 222 | |
| 223 | PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb()); |
| 224 | void* stackEnd = static_cast<void*>(pTib->StackBase); |
| 225 | FramePointerStackWalk(StackWalkCallback, kMaxFrames, this, fp, stackEnd); |
| 226 | #elif defined(XP_DARWIN) |
| 227 | // This avoids MozStackWalk(), which has become unusably slow on Mac due to |
| 228 | // changes in libunwind. |
| 229 | // |
| 230 | // This code is cribbed from the Gecko Profiler, which also uses |
| 231 | // FramePointerStackWalk() on Mac: Registers::SyncPopulate() for the frame |
| 232 | // pointer, and GetStackTop() for the stack end. |
| 233 | # pragma GCC diagnostic push |
| 234 | # pragma GCC diagnostic ignored "-Wframe-address" |
| 235 | void** fp = reinterpret_cast<void**>(__builtin_frame_address(1)); |
| 236 | # pragma GCC diagnostic pop |
| 237 | void* stackEnd = pthread_get_stackaddr_np(pthread_self()); |
| 238 | FramePointerStackWalk(StackWalkCallback, kMaxFrames, this, fp, stackEnd); |
| 239 | #else |
| 240 | MozStackWalk(StackWalkCallback, nullptr, kMaxFrames, this); |
| 241 | #endif |
| 242 | } |
| 243 | |
| 244 | //--------------------------------------------------------------------------- |
| 245 | // Logging |
| 246 | //--------------------------------------------------------------------------- |
| 247 | |
| 248 | // Change this to 1 to enable some PHC logging. Useful for debugging. |
| 249 | #define PHC_LOGGING0 0 |
| 250 | |
| 251 | #if PHC_LOGGING0 |
| 252 | |
| 253 | static size_t GetPid() { return size_t(getpid()); } |
| 254 | |
| 255 | static size_t GetTid() { |
| 256 | # if defined(XP_WIN) |
| 257 | return size_t(GetCurrentThreadId()); |
| 258 | # else |
| 259 | return size_t(pthread_self()); |
| 260 | # endif |
| 261 | } |
| 262 | |
| 263 | # if defined(XP_WIN) |
| 264 | # define LOG_STDERR \ |
| 265 | reinterpret_cast<intptr_t>(GetStdHandle(STD_ERROR_HANDLE)) |
| 266 | # else |
| 267 | # define LOG_STDERR 2 |
| 268 | # endif |
| 269 | # define LOG(fmt, ...) \ |
| 270 | FdPrintf(LOG_STDERR, "PHC[%zu,%zu,~%zu] " fmt, GetPid(), GetTid(), \ |
| 271 | size_t(PHC::Now()), ##__VA_ARGS__) |
| 272 | |
| 273 | #else |
| 274 | |
| 275 | # define LOG(fmt, ...) |
| 276 | |
| 277 | #endif // PHC_LOGGING |
| 278 | |
| 279 | //--------------------------------------------------------------------------- |
| 280 | // Global state |
| 281 | //--------------------------------------------------------------------------- |
| 282 | |
| 283 | // Throughout this entire file time is measured as the number of sub-page |
| 284 | // allocations performed (by PHC and mozjemalloc combined). `Time` is 64-bit |
| 285 | // because we could have more than 2**32 allocations in a long-running session. |
| 286 | // `Delay` is 32-bit because the delays used within PHC are always much smaller |
| 287 | // than 2**32. Delay must be unsigned so that IsPowerOfTwo() can work on some |
| 288 | // Delay values. |
| 289 | using Time = uint64_t; // A moment in time. |
| 290 | using Delay = uint32_t; // A time duration. |
| 291 | static constexpr Delay DELAY_MAX = UINT32_MAX(4294967295U) / 2; |
| 292 | |
| 293 | // PHC only runs if the page size is 4 KiB; anything more is uncommon and would |
| 294 | // use too much memory. So we hardwire this size for all platforms but macOS |
| 295 | // on ARM processors. For the latter we make an exception because the minimum |
| 296 | // page size supported is 16KiB so there's no way to go below that. |
| 297 | static const size_t kPageSize = |
| 298 | #if defined(XP_DARWIN) && defined(__aarch64__) |
| 299 | 16384 |
| 300 | #else |
| 301 | 4096 |
| 302 | #endif |
| 303 | ; |
| 304 | |
| 305 | // We align the PHC area to a multiple of the jemalloc and JS GC chunk size |
| 306 | // (both use 1MB aligned chunks) so that their address computations don't lead |
| 307 | // from non-PHC memory into PHC memory causing misleading PHC stacks to be |
| 308 | // attached to a crash report. |
| 309 | static const size_t kPhcAlign = 1024 * 1024; |
| 310 | |
| 311 | static_assert(IsPowerOfTwo(kPhcAlign)); |
| 312 | static_assert((kPhcAlign % kPageSize) == 0); |
| 313 | |
| 314 | // There are two kinds of page. |
| 315 | // - Allocation pages, from which allocations are made. |
| 316 | // - Guard pages, which are never touched by PHC. |
| 317 | // |
| 318 | // These page kinds are interleaved; each allocation page has a guard page on |
| 319 | // either side. |
| 320 | #ifdef EARLY_BETA_OR_EARLIER1 |
| 321 | static const size_t kNumAllocPages = kPageSize == 4096 ? 4096 : 1024; |
| 322 | #else |
| 323 | // This will use between 82KiB and 1.1MiB per process (depending on how many |
| 324 | // objects are currently allocated). We will tune this in the future. |
| 325 | static const size_t kNumAllocPages = kPageSize == 4096 ? 256 : 64; |
| 326 | #endif |
| 327 | static const size_t kNumAllPages = kNumAllocPages * 2 + 1; |
| 328 | |
| 329 | // The total size of the allocation pages and guard pages. |
| 330 | static const size_t kAllPagesSize = kNumAllPages * kPageSize; |
| 331 | |
| 332 | // jemalloc adds a guard page to the end of our allocation, see the comment in |
| 333 | // AllocAllPages() for more information. |
| 334 | static const size_t kAllPagesJemallocSize = kAllPagesSize - kPageSize; |
| 335 | |
| 336 | // The amount to decrement from the shared allocation delay each time a thread's |
| 337 | // local allocation delay reaches zero. |
| 338 | static const Delay kDelayDecrementAmount = 256; |
| 339 | |
| 340 | // When PHC is disabled on the current thread wait this many allocations before |
| 341 | // accessing sAllocDelay once more. |
| 342 | static const Delay kDelayBackoffAmount = 64; |
| 343 | |
| 344 | // When PHC is disabled globally reset the shared delay by this many allocations |
| 345 | // to keep code running on the fast path. |
| 346 | static const Delay kDelayResetWhenDisabled = 64 * 1024; |
| 347 | |
| 348 | // The default state for PHC. Either Enabled or OnlyFree. |
| 349 | #define DEFAULT_STATEmozilla::phc::OnlyFree mozilla::phc::OnlyFree |
| 350 | |
| 351 | // The maximum time. |
| 352 | static const Time kMaxTime = ~(Time(0)); |
| 353 | |
| 354 | // Truncate aRnd to the range (1 .. aAvgDelay*2). If aRnd is random, this |
| 355 | // results in an average value of aAvgDelay + 0.5, which is close enough to |
| 356 | // aAvgDelay. aAvgDelay must be a power-of-two for speed. |
| 357 | constexpr Delay Rnd64ToDelay(Delay aAvgDelay, uint64_t aRnd) { |
| 358 | MOZ_ASSERT(IsPowerOfTwo(aAvgDelay), "must be a power of two")do { static_assert( mozilla::detail::AssertionConditionType< decltype(IsPowerOfTwo(aAvgDelay))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(IsPowerOfTwo(aAvgDelay)))), 0 ))) { do { } while (false); MOZ_ReportAssertionFailure("IsPowerOfTwo(aAvgDelay)" " (" "must be a power of two" ")", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 358); AnnotateMozCrashReason("MOZ_ASSERT" "(" "IsPowerOfTwo(aAvgDelay)" ") (" "must be a power of two" ")"); do { *((volatile int*)__null ) = 358; __attribute__((nomerge)) ::abort(); } while (false); } } while (false); |
| 359 | |
| 360 | return (aRnd & (uint64_t(aAvgDelay) * 2 - 1)) + 1; |
| 361 | } |
| 362 | |
| 363 | static Delay CheckProbability(int64_t aProb) { |
| 364 | // Limit delays calculated from prefs to 0x80000000, this is the largest |
| 365 | // power-of-two that fits in a Delay since it is a uint32_t. |
| 366 | // The minimum is 2 that way not every allocation goes straight to PHC. |
| 367 | return RoundUpPow2( |
| 368 | std::min(std::max(aProb, int64_t(2)), int64_t(0x80000000))); |
| 369 | } |
| 370 | |
| 371 | // Maps a pointer to a PHC-specific structure: |
| 372 | // - Nothing |
| 373 | // - A guard page (it is unspecified which one) |
| 374 | // - An allocation page (with an index < kNumAllocPages) |
| 375 | // |
| 376 | // The standard way of handling a PtrKind is to check IsNothing(), and if that |
| 377 | // fails, to check IsGuardPage(), and if that fails, to call AllocPage(). |
| 378 | class PtrKind { |
| 379 | private: |
| 380 | enum class Tag : uint8_t { |
| 381 | Nothing, |
| 382 | GuardPage, |
| 383 | AllocPage, |
| 384 | }; |
| 385 | |
| 386 | Tag mTag; |
| 387 | uintptr_t mIndex; // Only used if mTag == Tag::AllocPage. |
| 388 | |
| 389 | public: |
| 390 | // Detect what a pointer points to. This constructor must be fast because it |
| 391 | // is called for every call to free(), realloc(), malloc_usable_size(), and |
| 392 | // jemalloc_ptr_info(). |
| 393 | PtrKind(const void* aPtr, const uint8_t* aPagesStart, |
| 394 | const uint8_t* aPagesLimit) { |
| 395 | if (!(aPagesStart <= aPtr && aPtr < aPagesLimit)) { |
| 396 | mTag = Tag::Nothing; |
| 397 | } else { |
| 398 | uintptr_t offset = static_cast<const uint8_t*>(aPtr) - aPagesStart; |
| 399 | uintptr_t allPageIndex = offset / kPageSize; |
| 400 | MOZ_ASSERT(allPageIndex < kNumAllPages)do { static_assert( mozilla::detail::AssertionConditionType< decltype(allPageIndex < kNumAllPages)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(allPageIndex < kNumAllPages ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "allPageIndex < kNumAllPages", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 400); AnnotateMozCrashReason("MOZ_ASSERT" "(" "allPageIndex < kNumAllPages" ")"); do { *((volatile int*)__null) = 400; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 401 | if (allPageIndex & 1) { |
| 402 | // Odd-indexed pages are allocation pages. |
| 403 | uintptr_t allocPageIndex = allPageIndex / 2; |
| 404 | MOZ_ASSERT(allocPageIndex < kNumAllocPages)do { static_assert( mozilla::detail::AssertionConditionType< decltype(allocPageIndex < kNumAllocPages)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(allocPageIndex < kNumAllocPages ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "allocPageIndex < kNumAllocPages", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 404); AnnotateMozCrashReason("MOZ_ASSERT" "(" "allocPageIndex < kNumAllocPages" ")"); do { *((volatile int*)__null) = 404; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 405 | mTag = Tag::AllocPage; |
| 406 | mIndex = allocPageIndex; |
| 407 | } else { |
| 408 | // Even-numbered pages are guard pages. |
| 409 | mTag = Tag::GuardPage; |
| 410 | } |
| 411 | } |
| 412 | } |
| 413 | |
| 414 | bool IsNothing() const { return mTag == Tag::Nothing; } |
| 415 | bool IsGuardPage() const { return mTag == Tag::GuardPage; } |
| 416 | |
| 417 | // This should only be called after IsNothing() and IsGuardPage() have been |
| 418 | // checked and failed. |
| 419 | uintptr_t AllocPageIndex() const { |
| 420 | MOZ_RELEASE_ASSERT(mTag == Tag::AllocPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mTag == Tag::AllocPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mTag == Tag::AllocPage))), 0 ))) { do { } while (false); MOZ_ReportAssertionFailure("mTag == Tag::AllocPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 420); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "mTag == Tag::AllocPage" ")"); do { *((volatile int*)__null) = 420; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 421 | return mIndex; |
| 422 | } |
| 423 | }; |
| 424 | |
| 425 | // On MacOS, the first __thread/thread_local access calls malloc, which leads |
| 426 | // to an infinite loop. So we use pthread-based TLS instead, which somehow |
| 427 | // doesn't have this problem. |
| 428 | #if !defined(XP_DARWIN) |
| 429 | # define PHC_THREAD_LOCAL(T)__thread ::mozilla::detail::ThreadLocal< T, ::mozilla::detail ::ThreadLocalNativeStorage> MOZ_THREAD_LOCAL(T)__thread ::mozilla::detail::ThreadLocal< T, ::mozilla::detail ::ThreadLocalNativeStorage> |
| 430 | #else |
| 431 | # define PHC_THREAD_LOCAL(T)__thread ::mozilla::detail::ThreadLocal< T, ::mozilla::detail ::ThreadLocalNativeStorage> \ |
| 432 | detail::ThreadLocal<T, detail::ThreadLocalKeyStorage> |
| 433 | #endif |
| 434 | |
| 435 | // The virtual address space reserved by PHC. It is shared, immutable global |
| 436 | // state. Initialized by phc_init() and never changed after that. phc_init() |
| 437 | // runs early enough that no synchronization is needed. |
| 438 | class PHCRegion { |
| 439 | private: |
| 440 | // The bounds of the allocated pages. |
| 441 | uint8_t* const mPagesStart; |
| 442 | uint8_t* const mPagesLimit; |
| 443 | |
| 444 | // Allocates the allocation pages and the guard pages, contiguously. |
| 445 | uint8_t* AllocAllPages() { |
| 446 | // The memory allocated here is never freed, because it would happen at |
| 447 | // process termination when it would be of little use. |
| 448 | |
| 449 | // We can rely on jemalloc's behaviour that when it allocates memory aligned |
| 450 | // with its own chunk size it will over-allocate and guarantee that the |
| 451 | // memory after the end of our allocation, but before the next chunk, is |
| 452 | // decommitted and inaccessible. Elsewhere in PHC we assume that we own |
| 453 | // that page (so that memory errors in it get caught by PHC) but here we |
| 454 | // use kAllPagesJemallocSize which subtracts jemalloc's guard page. |
| 455 | void* pages = MozJemalloc::memalign(kPhcAlign, kAllPagesJemallocSize); |
| 456 | if (!pages) { |
| 457 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 457); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile int*)__null) = 457; __attribute__((nomerge)) ::abort(); } while (false); } while (false); |
| 458 | } |
| 459 | |
| 460 | // Make the pages inaccessible. |
| 461 | #ifdef XP_WIN |
| 462 | if (!VirtualFree(pages, kAllPagesJemallocSize, MEM_DECOMMIT)) { |
| 463 | MOZ_CRASH("VirtualFree failed")do { do { } while (false); MOZ_ReportCrash("" "VirtualFree failed" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 463); AnnotateMozCrashReason("MOZ_CRASH(" "VirtualFree failed" ")"); do { *((volatile int*)__null) = 463; __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
| 464 | } |
| 465 | #else |
| 466 | if (mmap_mmap(pages, kAllPagesJemallocSize, PROT_NONE0x0, |
| 467 | MAP_FIXED0x10 | MAP_PRIVATE0x02 | MAP_ANON0x20, -1, 0) == MAP_FAILED((void *) -1)) { |
| 468 | MOZ_CRASH("mmap failed")do { do { } while (false); MOZ_ReportCrash("" "mmap failed", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 468); AnnotateMozCrashReason("MOZ_CRASH(" "mmap failed" ")" ); do { *((volatile int*)__null) = 468; __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
| 469 | } |
| 470 | #endif |
| 471 | |
| 472 | return static_cast<uint8_t*>(pages); |
| 473 | } |
| 474 | |
| 475 | public: |
| 476 | PHCRegion(); |
| 477 | |
| 478 | class PtrKind PtrKind(const void* aPtr) { |
| 479 | class PtrKind pk(aPtr, mPagesStart, mPagesLimit); |
| 480 | return pk; |
| 481 | } |
| 482 | |
| 483 | bool IsInFirstGuardPage(const void* aPtr) { |
| 484 | return mPagesStart <= aPtr && aPtr < mPagesStart + kPageSize; |
| 485 | } |
| 486 | |
| 487 | // Get the address of the allocation page referred to via an index. Used when |
| 488 | // marking the page as accessible/inaccessible. |
| 489 | uint8_t* AllocPagePtr(uintptr_t aIndex) { |
| 490 | MOZ_ASSERT(aIndex < kNumAllocPages)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aIndex < kNumAllocPages)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aIndex < kNumAllocPages)) ), 0))) { do { } while (false); MOZ_ReportAssertionFailure("aIndex < kNumAllocPages" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 490); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aIndex < kNumAllocPages" ")"); do { *((volatile int*)__null) = 490; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 491 | // Multiply by two and add one to account for allocation pages *and* guard |
| 492 | // pages. |
| 493 | return mPagesStart + (2 * aIndex + 1) * kPageSize; |
| 494 | } |
| 495 | }; |
| 496 | |
| 497 | // This type is used as a proof-of-lock token, to make it clear which functions |
| 498 | // require mMutex to be locked. |
| 499 | using PHCLock = const MutexAutoLock&; |
| 500 | |
| 501 | // Shared, mutable global state. Many fields are protected by sMutex; functions |
| 502 | // that access those feilds should take a PHCLock as proof that mMutex is held. |
| 503 | // Other fields are TLS or Atomic and don't need the lock. |
| 504 | class PHC { |
Excessive padding in 'class PHC' (80 padding bytes, where 16 is optimal). Optimal fields order: mAvgFirstAllocDelay, mPhcState, mNow, mRNG, mFreePageListHead, mFreePageListTail, mMutex, mAllocPages, mAvgAllocDelay, mAvgPageReuseDelay, consider reordering the fields or adding explicit padding members | |
| 505 | enum class AllocPageState { |
| 506 | NeverAllocated = 0, |
| 507 | InUse = 1, |
| 508 | Freed = 2, |
| 509 | }; |
| 510 | |
| 511 | // Metadata for each allocation page. |
| 512 | class AllocPageInfo { |
| 513 | public: |
| 514 | AllocPageInfo() |
| 515 | : mState(AllocPageState::NeverAllocated), |
| 516 | mBaseAddr(nullptr), |
| 517 | mReuseTime(0) {} |
| 518 | |
| 519 | // The current allocation page state. |
| 520 | AllocPageState mState; |
| 521 | |
| 522 | // The arena that the allocation is nominally from. This isn't meaningful |
| 523 | // within PHC, which has no arenas. But it is necessary for reallocation of |
| 524 | // page allocations as normal allocations, such as in this code: |
| 525 | // |
| 526 | // p = moz_arena_malloc(arenaId, 4096); |
| 527 | // realloc(p, 8192); |
| 528 | // |
| 529 | // The realloc is more than one page, and thus too large for PHC to handle. |
| 530 | // Therefore, if PHC handles the first allocation, it must ask mozjemalloc |
| 531 | // to allocate the 8192 bytes in the correct arena, and to do that, it must |
| 532 | // call MozJemalloc::moz_arena_malloc with the correct arenaId under the |
| 533 | // covers. Therefore it must record that arenaId. |
| 534 | // |
| 535 | // This field is also needed for jemalloc_ptr_info() to work, because it |
| 536 | // also returns the arena ID (but only in debug builds). |
| 537 | // |
| 538 | // - NeverAllocated: must be 0. |
| 539 | // - InUse | Freed: can be any valid arena ID value. |
| 540 | Maybe<arena_id_t> mArenaId; |
| 541 | |
| 542 | // The starting address of the allocation. Will not be the same as the page |
| 543 | // address unless the allocation is a full page. |
| 544 | // - NeverAllocated: must be 0. |
| 545 | // - InUse | Freed: must be within the allocation page. |
| 546 | uint8_t* mBaseAddr; |
| 547 | |
| 548 | // Usable size is computed as the number of bytes between the pointer and |
| 549 | // the end of the allocation page. This might be bigger than the requested |
| 550 | // size, especially if an outsized alignment is requested. |
| 551 | size_t UsableSize() const { |
| 552 | return mState == AllocPageState::NeverAllocated |
| 553 | ? 0 |
| 554 | : kPageSize - (reinterpret_cast<uintptr_t>(mBaseAddr) & |
| 555 | (kPageSize - 1)); |
| 556 | } |
| 557 | |
| 558 | // The internal fragmentation for this allocation. |
| 559 | size_t FragmentationBytes() const { |
| 560 | MOZ_ASSERT(kPageSize >= UsableSize())do { static_assert( mozilla::detail::AssertionConditionType< decltype(kPageSize >= UsableSize())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(kPageSize >= UsableSize() ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "kPageSize >= UsableSize()", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 560); AnnotateMozCrashReason("MOZ_ASSERT" "(" "kPageSize >= UsableSize()" ")"); do { *((volatile int*)__null) = 560; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 561 | return mState == AllocPageState::InUse ? kPageSize - UsableSize() : 0; |
| 562 | } |
| 563 | |
| 564 | // The allocation stack. |
| 565 | // - NeverAllocated: Nothing. |
| 566 | // - InUse | Freed: Some. |
| 567 | Maybe<StackTrace> mAllocStack; |
| 568 | |
| 569 | // The free stack. |
| 570 | // - NeverAllocated | InUse: Nothing. |
| 571 | // - Freed: Some. |
| 572 | Maybe<StackTrace> mFreeStack; |
| 573 | |
| 574 | // The time at which the page is available for reuse, as measured against |
| 575 | // mNow. When the page is in use this value will be kMaxTime. |
| 576 | // - NeverAllocated: must be 0. |
| 577 | // - InUse: must be kMaxTime. |
| 578 | // - Freed: must be > 0 and < kMaxTime. |
| 579 | Time mReuseTime; |
| 580 | |
| 581 | // The next index for a free list of pages.` |
| 582 | Maybe<uintptr_t> mNextPage; |
| 583 | }; |
| 584 | |
| 585 | public: |
| 586 | // The RNG seeds here are poor, but non-reentrant since this can be called |
| 587 | // from malloc(). SetState() will reset the RNG later. |
| 588 | PHC() : mRNG(RandomSeed<1>(), RandomSeed<2>()) { |
| 589 | mMutex.Init(); |
| 590 | if (!tlsIsDisabled.init()) { |
| 591 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 591); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile int*)__null) = 591; __attribute__((nomerge)) ::abort(); } while (false); } while (false); |
| 592 | } |
| 593 | if (!tlsAllocDelay.init()) { |
| 594 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 594); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile int*)__null) = 594; __attribute__((nomerge)) ::abort(); } while (false); } while (false); |
| 595 | } |
| 596 | if (!tlsLastDelay.init()) { |
| 597 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 597); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile int*)__null) = 597; __attribute__((nomerge)) ::abort(); } while (false); } while (false); |
| 598 | } |
| 599 | |
| 600 | // This constructor is part of PHC's very early initialisation, |
| 601 | // see phc_init(), and if PHC is default-on it'll start marking allocations |
| 602 | // and we must setup the delay. However once XPCOM starts it'll call |
| 603 | // SetState() which will re-initialise the RNG and allocation delay. |
| 604 | MutexAutoLock lock(mMutex); |
| 605 | |
| 606 | ForceSetNewAllocDelay(Rnd64ToDelay(mAvgFirstAllocDelay, Random64(lock))); |
| 607 | |
| 608 | for (uintptr_t i = 0; i < kNumAllocPages; i++) { |
| 609 | AppendPageToFreeList(lock, i); |
| 610 | } |
| 611 | } |
| 612 | |
| 613 | uint64_t Random64(PHCLock) { return mRNG.next(); } |
| 614 | |
| 615 | bool IsPageInUse(PHCLock, uintptr_t aIndex) { |
| 616 | return mAllocPages[aIndex].mState == AllocPageState::InUse; |
| 617 | } |
| 618 | |
| 619 | // Is the page free? And if so, has enough time passed that we can use it? |
| 620 | bool IsPageAllocatable(PHCLock, uintptr_t aIndex, Time aNow) { |
| 621 | const AllocPageInfo& page = mAllocPages[aIndex]; |
| 622 | return page.mState != AllocPageState::InUse && aNow >= page.mReuseTime; |
| 623 | } |
| 624 | |
| 625 | // Get the address of the allocation page referred to via an index. Used |
| 626 | // when checking pointers against page boundaries. |
| 627 | uint8_t* AllocPageBaseAddr(PHCLock, uintptr_t aIndex) { |
| 628 | return mAllocPages[aIndex].mBaseAddr; |
| 629 | } |
| 630 | |
| 631 | Maybe<arena_id_t> PageArena(PHCLock aLock, uintptr_t aIndex) { |
| 632 | const AllocPageInfo& page = mAllocPages[aIndex]; |
| 633 | AssertAllocPageInUse(aLock, page); |
| 634 | |
| 635 | return page.mArenaId; |
| 636 | } |
| 637 | |
| 638 | size_t PageUsableSize(PHCLock aLock, uintptr_t aIndex) { |
| 639 | const AllocPageInfo& page = mAllocPages[aIndex]; |
| 640 | AssertAllocPageInUse(aLock, page); |
| 641 | |
| 642 | return page.UsableSize(); |
| 643 | } |
| 644 | |
| 645 | // The total fragmentation in PHC |
| 646 | size_t FragmentationBytes() const { |
| 647 | size_t sum = 0; |
| 648 | for (const auto& page : mAllocPages) { |
| 649 | sum += page.FragmentationBytes(); |
| 650 | } |
| 651 | return sum; |
| 652 | } |
| 653 | |
| 654 | void SetPageInUse(PHCLock aLock, uintptr_t aIndex, |
| 655 | const Maybe<arena_id_t>& aArenaId, uint8_t* aBaseAddr, |
| 656 | const StackTrace& aAllocStack) { |
| 657 | AllocPageInfo& page = mAllocPages[aIndex]; |
| 658 | AssertAllocPageNotInUse(aLock, page); |
| 659 | |
| 660 | page.mState = AllocPageState::InUse; |
| 661 | page.mArenaId = aArenaId; |
| 662 | page.mBaseAddr = aBaseAddr; |
| 663 | page.mAllocStack = Some(aAllocStack); |
| 664 | page.mFreeStack = Nothing(); |
| 665 | page.mReuseTime = kMaxTime; |
| 666 | MOZ_ASSERT(!page.mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!page.mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!page.mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!page.mNextPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 666); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { *((volatile int*)__null) = 666; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 667 | } |
| 668 | |
| 669 | #if PHC_LOGGING0 |
| 670 | Time GetFreeTime(uintptr_t aIndex) const { return mFreeTime[aIndex]; } |
| 671 | #endif |
| 672 | |
| 673 | void ResizePageInUse(PHCLock aLock, uintptr_t aIndex, |
| 674 | const Maybe<arena_id_t>& aArenaId, uint8_t* aNewBaseAddr, |
| 675 | const StackTrace& aAllocStack) { |
| 676 | AllocPageInfo& page = mAllocPages[aIndex]; |
| 677 | AssertAllocPageInUse(aLock, page); |
| 678 | |
| 679 | // page.mState is not changed. |
| 680 | if (aArenaId.isSome()) { |
| 681 | // Crash if the arenas don't match. |
| 682 | MOZ_RELEASE_ASSERT(page.mArenaId == aArenaId)do { static_assert( mozilla::detail::AssertionConditionType< decltype(page.mArenaId == aArenaId)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(page.mArenaId == aArenaId))) , 0))) { do { } while (false); MOZ_ReportAssertionFailure("page.mArenaId == aArenaId" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 682); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "page.mArenaId == aArenaId" ")"); do { *((volatile int*)__null) = 682; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 683 | } |
| 684 | page.mBaseAddr = aNewBaseAddr; |
| 685 | // We could just keep the original alloc stack, but the realloc stack is |
| 686 | // more recent and therefore seems more useful. |
| 687 | page.mAllocStack = Some(aAllocStack); |
| 688 | // page.mFreeStack is not changed. |
| 689 | // page.mReuseTime is not changed. |
| 690 | // page.mNextPage is not changed. |
| 691 | }; |
| 692 | |
| 693 | void SetPageFreed(PHCLock aLock, uintptr_t aIndex, |
| 694 | const Maybe<arena_id_t>& aArenaId, |
| 695 | const StackTrace& aFreeStack, Delay aReuseDelay) { |
| 696 | AllocPageInfo& page = mAllocPages[aIndex]; |
| 697 | AssertAllocPageInUse(aLock, page); |
| 698 | |
| 699 | page.mState = AllocPageState::Freed; |
| 700 | |
| 701 | // page.mArenaId is left unchanged, for jemalloc_ptr_info() calls that |
| 702 | // occur after freeing (e.g. in the PtrInfo test in TestJemalloc.cpp). |
| 703 | if (aArenaId.isSome()) { |
| 704 | // Crash if the arenas don't match. |
| 705 | MOZ_RELEASE_ASSERT(page.mArenaId == aArenaId)do { static_assert( mozilla::detail::AssertionConditionType< decltype(page.mArenaId == aArenaId)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(page.mArenaId == aArenaId))) , 0))) { do { } while (false); MOZ_ReportAssertionFailure("page.mArenaId == aArenaId" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 705); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "page.mArenaId == aArenaId" ")"); do { *((volatile int*)__null) = 705; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 706 | } |
| 707 | |
| 708 | // page.musableSize is left unchanged, for reporting on UAF, and for |
| 709 | // jemalloc_ptr_info() calls that occur after freeing (e.g. in the PtrInfo |
| 710 | // test in TestJemalloc.cpp). |
| 711 | |
| 712 | // page.mAllocStack is left unchanged, for reporting on UAF. |
| 713 | |
| 714 | page.mFreeStack = Some(aFreeStack); |
| 715 | Time now = Now(); |
| 716 | #if PHC_LOGGING0 |
| 717 | mFreeTime[aIndex] = now; |
| 718 | #endif |
| 719 | page.mReuseTime = now + aReuseDelay; |
| 720 | |
| 721 | MOZ_ASSERT(!page.mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!page.mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!page.mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!page.mNextPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 721); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { *((volatile int*)__null) = 721; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 722 | AppendPageToFreeList(aLock, aIndex); |
| 723 | } |
| 724 | |
| 725 | static void CrashOnGuardPage(void* aPtr) { |
| 726 | // An operation on a guard page? This is a bounds violation. Deliberately |
| 727 | // touch the page in question to cause a crash that triggers the usual PHC |
| 728 | // machinery. |
| 729 | LOG("CrashOnGuardPage(%p), bounds violation\n", aPtr); |
| 730 | *static_cast<uint8_t*>(aPtr) = 0; |
| 731 | MOZ_CRASH("unreachable")do { do { } while (false); MOZ_ReportCrash("" "unreachable", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 731); AnnotateMozCrashReason("MOZ_CRASH(" "unreachable" ")" ); do { *((volatile int*)__null) = 731; __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
| 732 | } |
| 733 | |
| 734 | void EnsureValidAndInUse(PHCLock, void* aPtr, uintptr_t aIndex) |
| 735 | MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
| 736 | const AllocPageInfo& page = mAllocPages[aIndex]; |
| 737 | |
| 738 | // The pointer must point to the start of the allocation. |
| 739 | MOZ_RELEASE_ASSERT(page.mBaseAddr == aPtr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(page.mBaseAddr == aPtr)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(page.mBaseAddr == aPtr))), 0 ))) { do { } while (false); MOZ_ReportAssertionFailure("page.mBaseAddr == aPtr" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 739); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "page.mBaseAddr == aPtr" ")"); do { *((volatile int*)__null) = 739; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 740 | |
| 741 | if (page.mState == AllocPageState::Freed) { |
| 742 | LOG("EnsureValidAndInUse(%p), use-after-free\n", aPtr); |
| 743 | // An operation on a freed page? This is a particular kind of |
| 744 | // use-after-free. Deliberately touch the page in question, in order to |
| 745 | // cause a crash that triggers the usual PHC machinery. But unlock mMutex |
| 746 | // first, because that self-same PHC machinery needs to re-lock it, and |
| 747 | // the crash causes non-local control flow so mMutex won't be unlocked |
| 748 | // the normal way in the caller. |
| 749 | mMutex.Unlock(); |
| 750 | *static_cast<uint8_t*>(aPtr) = 0; |
| 751 | MOZ_CRASH("unreachable")do { do { } while (false); MOZ_ReportCrash("" "unreachable", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 751); AnnotateMozCrashReason("MOZ_CRASH(" "unreachable" ")" ); do { *((volatile int*)__null) = 751; __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
| 752 | } |
| 753 | } |
| 754 | |
| 755 | // This expects GMUt::mMutex to be locked but can't check it with a parameter |
| 756 | // since we try-lock it. |
| 757 | void FillAddrInfo(uintptr_t aIndex, const void* aBaseAddr, bool isGuardPage, |
| 758 | phc::AddrInfo& aOut) { |
| 759 | const AllocPageInfo& page = mAllocPages[aIndex]; |
| 760 | if (isGuardPage) { |
| 761 | aOut.mKind = phc::AddrInfo::Kind::GuardPage; |
| 762 | } else { |
| 763 | switch (page.mState) { |
| 764 | case AllocPageState::NeverAllocated: |
| 765 | aOut.mKind = phc::AddrInfo::Kind::NeverAllocatedPage; |
| 766 | break; |
| 767 | |
| 768 | case AllocPageState::InUse: |
| 769 | aOut.mKind = phc::AddrInfo::Kind::InUsePage; |
| 770 | break; |
| 771 | |
| 772 | case AllocPageState::Freed: |
| 773 | aOut.mKind = phc::AddrInfo::Kind::FreedPage; |
| 774 | break; |
| 775 | |
| 776 | default: |
| 777 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 777); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile int*)__null) = 777; __attribute__((nomerge)) ::abort(); } while (false); } while (false); |
| 778 | } |
| 779 | } |
| 780 | aOut.mBaseAddr = page.mBaseAddr; |
| 781 | aOut.mUsableSize = page.UsableSize(); |
| 782 | aOut.mAllocStack = page.mAllocStack; |
| 783 | aOut.mFreeStack = page.mFreeStack; |
| 784 | } |
| 785 | |
| 786 | void FillJemallocPtrInfo(PHCLock, const void* aPtr, uintptr_t aIndex, |
| 787 | jemalloc_ptr_info_t* aInfo) { |
| 788 | const AllocPageInfo& page = mAllocPages[aIndex]; |
| 789 | switch (page.mState) { |
| 790 | case AllocPageState::NeverAllocated: |
| 791 | break; |
| 792 | |
| 793 | case AllocPageState::InUse: { |
| 794 | // Only return TagLiveAlloc if the pointer is within the bounds of the |
| 795 | // allocation's usable size. |
| 796 | uint8_t* base = page.mBaseAddr; |
| 797 | uint8_t* limit = base + page.UsableSize(); |
| 798 | if (base <= aPtr && aPtr < limit) { |
| 799 | *aInfo = {TagLiveAlloc, page.mBaseAddr, page.UsableSize(), |
| 800 | page.mArenaId.valueOr(0)}; |
| 801 | return; |
| 802 | } |
| 803 | break; |
| 804 | } |
| 805 | |
| 806 | case AllocPageState::Freed: { |
| 807 | // Only return TagFreedAlloc if the pointer is within the bounds of the |
| 808 | // former allocation's usable size. |
| 809 | uint8_t* base = page.mBaseAddr; |
| 810 | uint8_t* limit = base + page.UsableSize(); |
| 811 | if (base <= aPtr && aPtr < limit) { |
| 812 | *aInfo = {TagFreedAlloc, page.mBaseAddr, page.UsableSize(), |
| 813 | page.mArenaId.valueOr(0)}; |
| 814 | return; |
| 815 | } |
| 816 | break; |
| 817 | } |
| 818 | |
| 819 | default: |
| 820 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 820); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile int*)__null) = 820; __attribute__((nomerge)) ::abort(); } while (false); } while (false); |
| 821 | } |
| 822 | |
| 823 | // Pointers into guard pages will end up here, as will pointers into |
| 824 | // allocation pages that aren't within the allocation's bounds. |
| 825 | *aInfo = {TagUnknown, nullptr, 0, 0}; |
| 826 | } |
| 827 | |
| 828 | #ifndef XP_WIN |
| 829 | static void prefork() MOZ_NO_THREAD_SAFETY_ANALYSIS__attribute__((no_thread_safety_analysis)) { |
| 830 | PHC::sPHC->mMutex.Lock(); |
| 831 | } |
| 832 | static void postfork_parent() MOZ_NO_THREAD_SAFETY_ANALYSIS__attribute__((no_thread_safety_analysis)) { |
| 833 | PHC::sPHC->mMutex.Unlock(); |
| 834 | } |
| 835 | static void postfork_child() { PHC::sPHC->mMutex.Init(); } |
| 836 | #endif |
| 837 | |
| 838 | #if PHC_LOGGING0 |
| 839 | void IncPageAllocHits(PHCLock) { mPageAllocHits++; } |
| 840 | void IncPageAllocMisses(PHCLock) { mPageAllocMisses++; } |
| 841 | #else |
| 842 | void IncPageAllocHits(PHCLock) {} |
| 843 | void IncPageAllocMisses(PHCLock) {} |
| 844 | #endif |
| 845 | |
| 846 | phc::PHCStats GetPageStats(PHCLock) { |
| 847 | phc::PHCStats stats; |
| 848 | |
| 849 | for (const auto& page : mAllocPages) { |
| 850 | stats.mSlotsAllocated += page.mState == AllocPageState::InUse ? 1 : 0; |
| 851 | stats.mSlotsFreed += page.mState == AllocPageState::Freed ? 1 : 0; |
| 852 | } |
| 853 | stats.mSlotsUnused = |
| 854 | kNumAllocPages - stats.mSlotsAllocated - stats.mSlotsFreed; |
| 855 | |
| 856 | return stats; |
| 857 | } |
| 858 | |
| 859 | #if PHC_LOGGING0 |
| 860 | size_t PageAllocHits(PHCLock) { return mPageAllocHits; } |
| 861 | size_t PageAllocAttempts(PHCLock) { |
| 862 | return mPageAllocHits + mPageAllocMisses; |
| 863 | } |
| 864 | |
| 865 | // This is an integer because FdPrintf only supports integer printing. |
| 866 | size_t PageAllocHitRate(PHCLock) { |
| 867 | return mPageAllocHits * 100 / (mPageAllocHits + mPageAllocMisses); |
| 868 | } |
| 869 | #endif |
| 870 | |
| 871 | // Should we make new PHC allocations? |
| 872 | bool ShouldMakeNewAllocations() const { |
| 873 | return mPhcState == mozilla::phc::Enabled; |
| 874 | } |
| 875 | |
| 876 | using PHCState = mozilla::phc::PHCState; |
| 877 | void SetState(PHCState aState) { |
| 878 | if (mPhcState != PHCState::Enabled && aState == PHCState::Enabled) { |
| 879 | MutexAutoLock lock(mMutex); |
| 880 | // Reset the RNG at this point with a better seed. |
| 881 | ResetRNG(lock); |
| 882 | |
| 883 | ForceSetNewAllocDelay(Rnd64ToDelay(mAvgFirstAllocDelay, Random64(lock))); |
| 884 | } |
| 885 | |
| 886 | mPhcState = aState; |
| 887 | } |
| 888 | |
| 889 | void ResetRNG(MutexAutoLock&) { |
| 890 | mRNG = non_crypto::XorShift128PlusRNG(RandomSeed<0>(), RandomSeed<1>()); |
| 891 | } |
| 892 | |
| 893 | void SetProbabilities(int64_t aAvgDelayFirst, int64_t aAvgDelayNormal, |
| 894 | int64_t aAvgDelayPageReuse) { |
| 895 | MutexAutoLock lock(mMutex); |
| 896 | |
| 897 | mAvgFirstAllocDelay = CheckProbability(aAvgDelayFirst); |
| 898 | mAvgAllocDelay = CheckProbability(aAvgDelayNormal); |
| 899 | mAvgPageReuseDelay = CheckProbability(aAvgDelayPageReuse); |
| 900 | } |
| 901 | |
| 902 | static void DisableOnCurrentThread() { |
| 903 | MOZ_ASSERT(!tlsIsDisabled.get())do { static_assert( mozilla::detail::AssertionConditionType< decltype(!tlsIsDisabled.get())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!tlsIsDisabled.get()))), 0)) ) { do { } while (false); MOZ_ReportAssertionFailure("!tlsIsDisabled.get()" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 903); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!tlsIsDisabled.get()" ")"); do { *((volatile int*)__null) = 903; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 904 | tlsIsDisabled.set(true); |
| 905 | } |
| 906 | |
| 907 | void EnableOnCurrentThread() { |
| 908 | MOZ_ASSERT(tlsIsDisabled.get())do { static_assert( mozilla::detail::AssertionConditionType< decltype(tlsIsDisabled.get())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(tlsIsDisabled.get()))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("tlsIsDisabled.get()" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 908); AnnotateMozCrashReason("MOZ_ASSERT" "(" "tlsIsDisabled.get()" ")"); do { *((volatile int*)__null) = 908; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 909 | tlsIsDisabled.set(false); |
| 910 | } |
| 911 | |
| 912 | static bool IsDisabledOnCurrentThread() { return tlsIsDisabled.get(); } |
| 913 | |
| 914 | static Time Now() { |
| 915 | if (!sPHC) { |
| 916 | return 0; |
| 917 | } |
| 918 | |
| 919 | return sPHC->mNow; |
| 920 | } |
| 921 | |
| 922 | void AdvanceNow(uint32_t delay = 0) { |
| 923 | mNow += tlsLastDelay.get() - delay; |
| 924 | tlsLastDelay.set(delay); |
| 925 | } |
| 926 | |
| 927 | // Decrements the delay and returns true if it's time to make a new PHC |
| 928 | // allocation. |
| 929 | static bool DecrementDelay() { |
| 930 | const Delay alloc_delay = tlsAllocDelay.get(); |
| 931 | |
| 932 | if (MOZ_LIKELY(alloc_delay > 0)(__builtin_expect(!!(alloc_delay > 0), 1))) { |
| 933 | tlsAllocDelay.set(alloc_delay - 1); |
| 934 | return false; |
| 935 | } |
| 936 | // The local delay has expired, check the shared delay. This path is also |
| 937 | // executed on a new thread's first allocation, the result is the same: all |
| 938 | // the thread's TLS fields will be initialised. |
| 939 | |
| 940 | // This accesses sPHC but we want to ensure it's still a static member |
| 941 | // function so that sPHC isn't dereferenced until after the hot path above. |
| 942 | MOZ_ASSERT(sPHC)do { static_assert( mozilla::detail::AssertionConditionType< decltype(sPHC)>::isValid, "invalid assertion condition"); if ((__builtin_expect(!!(!(!!(sPHC))), 0))) { do { } while (false ); MOZ_ReportAssertionFailure("sPHC", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 942); AnnotateMozCrashReason("MOZ_ASSERT" "(" "sPHC" ")"); do { *((volatile int*)__null) = 942; __attribute__((nomerge)) :: abort(); } while (false); } } while (false); |
| 943 | sPHC->AdvanceNow(); |
| 944 | |
| 945 | // Use an atomic fetch-and-subtract. This uses unsigned underflow semantics |
| 946 | // to avoid doing a full compare-and-swap. |
| 947 | Delay new_delay = (sAllocDelay -= kDelayDecrementAmount); |
| 948 | Delay old_delay = new_delay + kDelayDecrementAmount; |
| 949 | if (MOZ_LIKELY(new_delay < DELAY_MAX)(__builtin_expect(!!(new_delay < DELAY_MAX), 1))) { |
| 950 | // Normal case, we decremented the shared delay but it's not yet |
| 951 | // underflowed. |
| 952 | tlsAllocDelay.set(kDelayDecrementAmount); |
| 953 | tlsLastDelay.set(kDelayDecrementAmount); |
| 954 | LOG("Update sAllocDelay <- %zu, tlsAllocDelay <- %zu\n", |
| 955 | size_t(new_delay), size_t(kDelayDecrementAmount)); |
| 956 | return false; |
| 957 | } |
| 958 | |
| 959 | if (old_delay < new_delay) { |
| 960 | // The shared delay only just underflowed, so unless we hit exactly zero |
| 961 | // we should set our local counter and continue. |
| 962 | LOG("Update sAllocDelay <- %zu, tlsAllocDelay <- %zu\n", |
| 963 | size_t(new_delay), size_t(old_delay)); |
| 964 | if (old_delay == 0) { |
| 965 | // We don't need to set tlsAllocDelay because it's already zero, we know |
| 966 | // because the condition at the beginning of this function failed. |
| 967 | return true; |
| 968 | } |
| 969 | tlsAllocDelay.set(old_delay); |
| 970 | tlsLastDelay.set(old_delay); |
| 971 | return false; |
| 972 | } |
| 973 | |
| 974 | // The delay underflowed on another thread or a previous failed allocation |
| 975 | // by this thread. Return true and attempt the next allocation, if the |
| 976 | // other thread wins we'll check for that before committing. |
| 977 | LOG("Update sAllocDelay <- %zu, tlsAllocDelay <- %zu\n", size_t(new_delay), |
| 978 | size_t(alloc_delay)); |
| 979 | return true; |
| 980 | } |
| 981 | |
| 982 | static void ResetLocalAllocDelay(Delay aDelay = 0) { |
| 983 | // We could take some delay from the shared delay but we'd need a |
| 984 | // compare-and-swap because this is called on paths that don't make |
| 985 | // allocations. Or we can set the local delay to zero and let it get |
| 986 | // initialised on the next allocation. |
| 987 | tlsAllocDelay.set(aDelay); |
| 988 | tlsLastDelay.set(aDelay); |
| 989 | } |
| 990 | |
| 991 | static void ForceSetNewAllocDelay(Delay aNewAllocDelay) { |
| 992 | LOG("Setting sAllocDelay <- %zu\n", size_t(aNewAllocDelay)); |
| 993 | sAllocDelay = aNewAllocDelay; |
| 994 | ResetLocalAllocDelay(); |
| 995 | } |
| 996 | |
| 997 | // Set a new allocation delay and return true if the delay was less than zero |
| 998 | // (but it's unsigned so interpret it as signed) indicating that we won the |
| 999 | // race to make the next allocation. |
| 1000 | static bool SetNewAllocDelay(Delay aNewAllocDelay) { |
| 1001 | bool cas_retry; |
| 1002 | do { |
| 1003 | // We read the current delay on every iteration, we consider that the PHC |
| 1004 | // allocation is still "up for grabs" if sAllocDelay < 0. This is safe |
| 1005 | // even while other threads continuing to fetch-and-subtract sAllocDelay |
| 1006 | // in DecrementDelay(), up to DELAY_MAX (2^31) calls to DecrementDelay(). |
| 1007 | Delay read_delay = sAllocDelay; |
| 1008 | if (read_delay < DELAY_MAX) { |
| 1009 | // Another thread already set a valid delay. |
| 1010 | LOG("Observe delay %zu this thread lost the race\n", |
| 1011 | size_t(read_delay)); |
| 1012 | ResetLocalAllocDelay(); |
| 1013 | return false; |
| 1014 | } else { |
| 1015 | LOG("Preparing for CAS, read sAllocDelay %zu\n", size_t(read_delay)); |
| 1016 | } |
| 1017 | |
| 1018 | cas_retry = !sAllocDelay.compareExchange(read_delay, aNewAllocDelay); |
| 1019 | if (cas_retry) { |
| 1020 | LOG("Lost the CAS, sAllocDelay is now %zu\n", size_t(sAllocDelay)); |
| 1021 | cpu_pause(); |
| 1022 | // We raced against another thread and lost. |
| 1023 | } |
| 1024 | } while (cas_retry); |
| 1025 | LOG("Won the CAS, set sAllocDelay = %zu\n", size_t(sAllocDelay)); |
| 1026 | ResetLocalAllocDelay(); |
| 1027 | return true; |
| 1028 | } |
| 1029 | |
| 1030 | static Delay LocalAllocDelay() { return tlsAllocDelay.get(); } |
| 1031 | static Delay SharedAllocDelay() { return sAllocDelay; } |
| 1032 | |
| 1033 | static Delay LastDelay() { return tlsLastDelay.get(); } |
| 1034 | |
| 1035 | Maybe<uintptr_t> PopNextFreeIfAllocatable(const MutexAutoLock& lock, |
| 1036 | Time now) { |
| 1037 | if (!mFreePageListHead) { |
| 1038 | return Nothing(); |
| 1039 | } |
| 1040 | |
| 1041 | uintptr_t index = mFreePageListHead.value(); |
| 1042 | |
| 1043 | MOZ_RELEASE_ASSERT(index < kNumAllocPages)do { static_assert( mozilla::detail::AssertionConditionType< decltype(index < kNumAllocPages)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(index < kNumAllocPages))) , 0))) { do { } while (false); MOZ_ReportAssertionFailure("index < kNumAllocPages" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1043); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "index < kNumAllocPages" ")"); do { *((volatile int*)__null) = 1043; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1044 | AllocPageInfo& page = mAllocPages[index]; |
| 1045 | AssertAllocPageNotInUse(lock, page); |
| 1046 | |
| 1047 | if (!IsPageAllocatable(lock, index, now)) { |
| 1048 | return Nothing(); |
| 1049 | } |
| 1050 | |
| 1051 | mFreePageListHead = page.mNextPage; |
| 1052 | page.mNextPage = Nothing(); |
| 1053 | if (!mFreePageListHead) { |
| 1054 | mFreePageListTail = Nothing(); |
| 1055 | } |
| 1056 | |
| 1057 | return Some(index); |
| 1058 | } |
| 1059 | |
| 1060 | void UnpopNextFree(const MutexAutoLock& lock, uintptr_t index) { |
| 1061 | AllocPageInfo& page = mAllocPages[index]; |
| 1062 | MOZ_ASSERT(!page.mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!page.mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!page.mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!page.mNextPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1062); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { *((volatile int*)__null) = 1062; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1063 | |
| 1064 | page.mNextPage = mFreePageListHead; |
| 1065 | mFreePageListHead = Some(index); |
| 1066 | if (!mFreePageListTail) { |
| 1067 | mFreePageListTail = Some(index); |
| 1068 | } |
| 1069 | } |
| 1070 | |
| 1071 | void AppendPageToFreeList(const MutexAutoLock& lock, uintptr_t aIndex) { |
| 1072 | MOZ_RELEASE_ASSERT(aIndex < kNumAllocPages)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aIndex < kNumAllocPages)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aIndex < kNumAllocPages)) ), 0))) { do { } while (false); MOZ_ReportAssertionFailure("aIndex < kNumAllocPages" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1072); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "aIndex < kNumAllocPages" ")"); do { *((volatile int*)__null) = 1072; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1073 | AllocPageInfo& page = mAllocPages[aIndex]; |
| 1074 | MOZ_ASSERT(!page.mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!page.mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!page.mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!page.mNextPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1074); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { *((volatile int*)__null) = 1074; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1075 | MOZ_ASSERT(mFreePageListHead != Some(aIndex) &&do { static_assert( mozilla::detail::AssertionConditionType< decltype(mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mFreePageListHead != Some(aIndex ) && mFreePageListTail != Some(aIndex)))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex)" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1076); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex)" ")"); do { *((volatile int*)__null) = 1076; __attribute__((nomerge )) ::abort(); } while (false); } } while (false) |
| 1076 | mFreePageListTail != Some(aIndex))do { static_assert( mozilla::detail::AssertionConditionType< decltype(mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mFreePageListHead != Some(aIndex ) && mFreePageListTail != Some(aIndex)))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex)" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1076); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex)" ")"); do { *((volatile int*)__null) = 1076; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1077 | |
| 1078 | if (!mFreePageListTail) { |
| 1079 | // The list is empty this page will become the beginning and end. |
| 1080 | MOZ_ASSERT(!mFreePageListHead)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!mFreePageListHead)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!mFreePageListHead))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!mFreePageListHead" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1080); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!mFreePageListHead" ")"); do { *((volatile int*)__null) = 1080; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1081 | mFreePageListHead = Some(aIndex); |
| 1082 | } else { |
| 1083 | MOZ_ASSERT(mFreePageListTail.value() < kNumAllocPages)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mFreePageListTail.value() < kNumAllocPages)>:: isValid, "invalid assertion condition"); if ((__builtin_expect (!!(!(!!(mFreePageListTail.value() < kNumAllocPages))), 0) )) { do { } while (false); MOZ_ReportAssertionFailure("mFreePageListTail.value() < kNumAllocPages" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1083); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mFreePageListTail.value() < kNumAllocPages" ")"); do { *((volatile int*)__null) = 1083; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1084 | AllocPageInfo& tail_page = mAllocPages[mFreePageListTail.value()]; |
| 1085 | MOZ_ASSERT(!tail_page.mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!tail_page.mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!tail_page.mNextPage))), 0)) ) { do { } while (false); MOZ_ReportAssertionFailure("!tail_page.mNextPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1085); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!tail_page.mNextPage" ")"); do { *((volatile int*)__null) = 1085; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1086 | tail_page.mNextPage = Some(aIndex); |
| 1087 | } |
| 1088 | page.mNextPage = Nothing(); |
| 1089 | mFreePageListTail = Some(aIndex); |
| 1090 | } |
| 1091 | |
| 1092 | private: |
| 1093 | template <int N> |
| 1094 | uint64_t RandomSeed() { |
| 1095 | // An older version of this code used RandomUint64() here, but on Mac that |
| 1096 | // function uses arc4random(), which can allocate, which would cause |
| 1097 | // re-entry, which would be bad. So we just use time(), a local variable |
| 1098 | // address and a global variable address. These are mediocre sources of |
| 1099 | // entropy, but good enough for PHC. |
| 1100 | static_assert(N == 0 || N == 1 || N == 2, "must be 0, 1 or 2"); |
| 1101 | uint64_t seed; |
| 1102 | if (N == 0) { |
| 1103 | time_t t = time(nullptr); |
| 1104 | seed = t ^ (t << 32); |
| 1105 | } else if (N == 1) { |
| 1106 | seed = uintptr_t(&seed) ^ (uintptr_t(&seed) << 32); |
| 1107 | } else { |
| 1108 | seed = uintptr_t(&sRegion) ^ (uintptr_t(&sRegion) << 32); |
| 1109 | } |
| 1110 | return seed; |
| 1111 | } |
| 1112 | |
| 1113 | void AssertAllocPageInUse(PHCLock, const AllocPageInfo& aPage) { |
| 1114 | MOZ_ASSERT(aPage.mState == AllocPageState::InUse)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.mState == AllocPageState::InUse)>::isValid, "invalid assertion condition"); if ((__builtin_expect(!!(!(! !(aPage.mState == AllocPageState::InUse))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("aPage.mState == AllocPageState::InUse" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1114); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mState == AllocPageState::InUse" ")"); do { *((volatile int*)__null) = 1114; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1115 | // There is nothing to assert about aPage.mArenaId. |
| 1116 | MOZ_ASSERT(aPage.mBaseAddr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.mBaseAddr)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.mBaseAddr))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("aPage.mBaseAddr" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1116); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mBaseAddr" ")"); do { *((volatile int*)__null) = 1116; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1117 | MOZ_ASSERT(aPage.UsableSize() > 0)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.UsableSize() > 0)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.UsableSize() > 0))) , 0))) { do { } while (false); MOZ_ReportAssertionFailure("aPage.UsableSize() > 0" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1117); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.UsableSize() > 0" ")"); do { *((volatile int*)__null) = 1117; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1118 | MOZ_ASSERT(aPage.mAllocStack.isSome())do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.mAllocStack.isSome())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.mAllocStack.isSome())) ), 0))) { do { } while (false); MOZ_ReportAssertionFailure("aPage.mAllocStack.isSome()" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1118); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mAllocStack.isSome()" ")"); do { *((volatile int*)__null) = 1118; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1119 | MOZ_ASSERT(aPage.mFreeStack.isNothing())do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.mFreeStack.isNothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.mFreeStack.isNothing() ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "aPage.mFreeStack.isNothing()", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1119); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mFreeStack.isNothing()" ")"); do { *((volatile int*)__null) = 1119; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1120 | MOZ_ASSERT(aPage.mReuseTime == kMaxTime)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.mReuseTime == kMaxTime)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.mReuseTime == kMaxTime ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "aPage.mReuseTime == kMaxTime", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1120); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mReuseTime == kMaxTime" ")"); do { *((volatile int*)__null) = 1120; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1121 | MOZ_ASSERT(!aPage.mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!aPage.mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!aPage.mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!aPage.mNextPage" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1121); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!aPage.mNextPage" ")"); do { *((volatile int*)__null) = 1121; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1122 | } |
| 1123 | |
| 1124 | void AssertAllocPageNotInUse(PHCLock, const AllocPageInfo& aPage) { |
| 1125 | // We can assert a lot about `NeverAllocated` pages, but not much about |
| 1126 | // `Freed` pages. |
| 1127 | #ifdef DEBUG1 |
| 1128 | bool isFresh = aPage.mState == AllocPageState::NeverAllocated; |
| 1129 | MOZ_ASSERT(isFresh || aPage.mState == AllocPageState::Freed)do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh || aPage.mState == AllocPageState::Freed)> ::isValid, "invalid assertion condition"); if ((__builtin_expect (!!(!(!!(isFresh || aPage.mState == AllocPageState::Freed))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("isFresh || aPage.mState == AllocPageState::Freed" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1129); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh || aPage.mState == AllocPageState::Freed" ")"); do { *((volatile int*)__null) = 1129; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1130 | MOZ_ASSERT_IF(isFresh, aPage.mArenaId == Nothing())do { if (isFresh) { do { static_assert( mozilla::detail::AssertionConditionType <decltype(aPage.mArenaId == Nothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.mArenaId == Nothing()) )), 0))) { do { } while (false); MOZ_ReportAssertionFailure("aPage.mArenaId == Nothing()" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1130); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mArenaId == Nothing()" ")"); do { *((volatile int*)__null) = 1130; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); } } while ( false); |
| 1131 | MOZ_ASSERT(isFresh == (aPage.mBaseAddr == nullptr))do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh == (aPage.mBaseAddr == nullptr))>::isValid , "invalid assertion condition"); if ((__builtin_expect(!!(!( !!(isFresh == (aPage.mBaseAddr == nullptr)))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("isFresh == (aPage.mBaseAddr == nullptr)" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1131); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh == (aPage.mBaseAddr == nullptr)" ")"); do { *((volatile int*)__null) = 1131; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1132 | MOZ_ASSERT(isFresh == (aPage.mAllocStack.isNothing()))do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh == (aPage.mAllocStack.isNothing()))>::isValid , "invalid assertion condition"); if ((__builtin_expect(!!(!( !!(isFresh == (aPage.mAllocStack.isNothing())))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("isFresh == (aPage.mAllocStack.isNothing())" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1132); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh == (aPage.mAllocStack.isNothing())" ")"); do { *((volatile int*)__null) = 1132; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1133 | MOZ_ASSERT(isFresh == (aPage.mFreeStack.isNothing()))do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh == (aPage.mFreeStack.isNothing()))>::isValid , "invalid assertion condition"); if ((__builtin_expect(!!(!( !!(isFresh == (aPage.mFreeStack.isNothing())))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("isFresh == (aPage.mFreeStack.isNothing())" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1133); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh == (aPage.mFreeStack.isNothing())" ")"); do { *((volatile int*)__null) = 1133; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1134 | MOZ_ASSERT(aPage.mReuseTime != kMaxTime)do { static_assert( mozilla::detail::AssertionConditionType< decltype(aPage.mReuseTime != kMaxTime)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(aPage.mReuseTime != kMaxTime ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "aPage.mReuseTime != kMaxTime", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1134); AnnotateMozCrashReason("MOZ_ASSERT" "(" "aPage.mReuseTime != kMaxTime" ")"); do { *((volatile int*)__null) = 1134; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1135 | #endif |
| 1136 | } |
| 1137 | |
| 1138 | // To improve locality we try to order this file by how frequently different |
| 1139 | // fields are modified and place all the modified-together fields early and |
| 1140 | // ideally within a single cache line. |
| 1141 | public: |
| 1142 | // The mutex that protects the other members. |
| 1143 | alignas(kCacheLineSize) Mutex mMutex MOZ_UNANNOTATED; |
| 1144 | |
| 1145 | private: |
| 1146 | // The current time. We use ReleaseAcquire semantics since we attempt to |
| 1147 | // update this by larger increments and don't want to lose an entire update. |
| 1148 | Atomic<Time, ReleaseAcquire> mNow; |
| 1149 | |
| 1150 | // This will only ever be updated from one thread. The other threads should |
| 1151 | // eventually get the update. |
| 1152 | Atomic<PHCState, Relaxed> mPhcState = |
| 1153 | Atomic<PHCState, Relaxed>(DEFAULT_STATEmozilla::phc::OnlyFree); |
| 1154 | |
| 1155 | // RNG for deciding which allocations to treat specially. It doesn't need to |
| 1156 | // be high quality. |
| 1157 | // |
| 1158 | // This is a raw pointer for the reason explained in the comment above |
| 1159 | // PHC's constructor. Don't change it to UniquePtr or anything like that. |
| 1160 | non_crypto::XorShift128PlusRNG mRNG; |
| 1161 | |
| 1162 | // A linked list of free pages. Pages are allocated from the head of the list |
| 1163 | // and returned to the tail. The list will naturally order itself by "last |
| 1164 | // freed time" so if the head of the list can't satisfy an allocation due to |
| 1165 | // time then none of the pages can. |
| 1166 | Maybe<uintptr_t> mFreePageListHead; |
| 1167 | Maybe<uintptr_t> mFreePageListTail; |
| 1168 | |
| 1169 | #if PHC_LOGGING0 |
| 1170 | // How many allocations that could have been page allocs actually were? As |
| 1171 | // constrained kNumAllocPages. If the hit ratio isn't close to 100% it's |
| 1172 | // likely that the global constants are poorly chosen. |
| 1173 | size_t mPageAllocHits = 0; |
| 1174 | size_t mPageAllocMisses = 0; |
| 1175 | #endif |
| 1176 | |
| 1177 | // The remaining fields are updated much less often, place them on the next |
| 1178 | // cache line. |
| 1179 | |
| 1180 | // The average delay before doing any page allocations at the start of a |
| 1181 | // process. Note that roughly 1 million allocations occur in the main process |
| 1182 | // while starting the browser. The delay range is 1..gAvgFirstAllocDelay*2. |
| 1183 | alignas(kCacheLineSize) Delay mAvgFirstAllocDelay = 64 * 1024; |
| 1184 | |
| 1185 | // The average delay until the next attempted page allocation, once we get |
| 1186 | // past the first delay. The delay range is 1..kAvgAllocDelay*2. |
| 1187 | Delay mAvgAllocDelay = 16 * 1024; |
| 1188 | |
| 1189 | // The average delay before reusing a freed page. Should be significantly |
| 1190 | // larger than kAvgAllocDelay, otherwise there's not much point in having it. |
| 1191 | // The delay range is (kAvgAllocDelay / 2)..(kAvgAllocDelay / 2 * 3). This is |
| 1192 | // different to the other delay ranges in not having a minimum of 1, because |
| 1193 | // that's such a short delay that there is a high likelihood of bad stacks in |
| 1194 | // any crash report. |
| 1195 | Delay mAvgPageReuseDelay = 256 * 1024; |
| 1196 | |
| 1197 | // When true, PHC does as little as possible. |
| 1198 | // |
| 1199 | // (a) It does not allocate any new page allocations. |
| 1200 | // |
| 1201 | // (b) It avoids doing any operations that might call malloc/free/etc., which |
| 1202 | // would cause re-entry into PHC. (In practice, MozStackWalk() is the |
| 1203 | // only such operation.) Note that calls to the functions in MozJemalloc |
| 1204 | // are ok. |
| 1205 | // |
| 1206 | // For example, replace_malloc() will just fall back to mozjemalloc. However, |
| 1207 | // operations involving existing allocations are more complex, because those |
| 1208 | // existing allocations may be page allocations. For example, if |
| 1209 | // replace_free() is passed a page allocation on a PHC-disabled thread, it |
| 1210 | // will free the page allocation in the usual way, but it will get a dummy |
| 1211 | // freeStack in order to avoid calling MozStackWalk(), as per (b) above. |
| 1212 | // |
| 1213 | // This single disabling mechanism has two distinct uses. |
| 1214 | // |
| 1215 | // - It's used to prevent re-entry into PHC, which can cause correctness |
| 1216 | // problems. For example, consider this sequence. |
| 1217 | // |
| 1218 | // 1. enter replace_free() |
| 1219 | // 2. which calls PageFree() |
| 1220 | // 3. which calls MozStackWalk() |
| 1221 | // 4. which locks a mutex M, and then calls malloc |
| 1222 | // 5. enter replace_malloc() |
| 1223 | // 6. which calls MaybePageAlloc() |
| 1224 | // 7. which calls MozStackWalk() |
| 1225 | // 8. which (re)locks a mutex M --> deadlock |
| 1226 | // |
| 1227 | // We avoid this sequence by "disabling" the thread in PageFree() (at step |
| 1228 | // 2), which causes MaybePageAlloc() to fail, avoiding the call to |
| 1229 | // MozStackWalk() (at step 7). |
| 1230 | // |
| 1231 | // In practice, realloc or free of a PHC allocation is unlikely on a thread |
| 1232 | // that is disabled because of this use: MozStackWalk() will probably only |
| 1233 | // realloc/free allocations that it allocated itself, but those won't be |
| 1234 | // page allocations because PHC is disabled before calling MozStackWalk(). |
| 1235 | // |
| 1236 | // (Note that MaybePageAlloc() could safely do a page allocation so long as |
| 1237 | // it avoided calling MozStackWalk() by getting a dummy allocStack. But it |
| 1238 | // wouldn't be useful, and it would prevent the second use below.) |
| 1239 | // |
| 1240 | // - It's used to prevent PHC allocations in some tests that rely on |
| 1241 | // mozjemalloc's exact allocation behaviour, which PHC does not replicate |
| 1242 | // exactly. (Note that (b) isn't necessary for this use -- MozStackWalk() |
| 1243 | // could be safely called -- but it is necessary for the first use above.) |
| 1244 | // |
| 1245 | static PHC_THREAD_LOCAL(bool)__thread ::mozilla::detail::ThreadLocal< bool, ::mozilla:: detail::ThreadLocalNativeStorage> tlsIsDisabled; |
| 1246 | |
| 1247 | // Delay until the next attempt at a page allocation. The delay is made up of |
| 1248 | // two parts the global delay and each thread's local portion of that delay: |
| 1249 | // |
| 1250 | // delay = sDelay + sum_all_threads(tlsAllocDelay) |
| 1251 | // |
| 1252 | // Threads use their local delay to reduce contention on the shared delay. |
| 1253 | // |
| 1254 | // See the comment in MaybePageAlloc() for an explanation of why it uses |
| 1255 | // ReleaseAcquire semantics. |
| 1256 | static Atomic<Delay, ReleaseAcquire> sAllocDelay; |
| 1257 | static PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> tlsAllocDelay; |
| 1258 | |
| 1259 | // The last value we set tlsAllocDelay to before starting to count down. |
| 1260 | static PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> tlsLastDelay; |
| 1261 | |
| 1262 | AllocPageInfo mAllocPages[kNumAllocPages]; |
| 1263 | #if PHC_LOGGING0 |
| 1264 | Time mFreeTime[kNumAllocPages]; |
| 1265 | #endif |
| 1266 | |
| 1267 | public: |
| 1268 | Delay GetAvgAllocDelay(const MutexAutoLock&) { return mAvgAllocDelay; } |
| 1269 | Delay GetAvgFirstAllocDelay(const MutexAutoLock&) { |
| 1270 | return mAvgFirstAllocDelay; |
| 1271 | } |
| 1272 | Delay GetAvgPageReuseDelay(const MutexAutoLock&) { |
| 1273 | return mAvgPageReuseDelay; |
| 1274 | } |
| 1275 | |
| 1276 | // Both of these are accessed early on hot code paths. We make them both |
| 1277 | // static variables rathan making sRegion a member of sPHC to keep these hot |
| 1278 | // code paths as fast as possible. They're both "write once" so they can |
| 1279 | // share a cache line. |
| 1280 | static PHCRegion* sRegion; |
| 1281 | static PHC* sPHC; |
| 1282 | }; |
| 1283 | |
| 1284 | // These globals are read together and hardly ever written. They should be on |
| 1285 | // the same cache line. They should be in a different cache line to data that |
| 1286 | // is manipulated often (sMutex and mNow are members of sPHC for that reason) so |
| 1287 | // that this cache line can be shared amoung cores. This makes a measurable |
| 1288 | // impact to calls to maybe_init() |
| 1289 | alignas(kCacheLineSize) PHCRegion* PHC::sRegion; |
| 1290 | PHC* PHC::sPHC; |
| 1291 | |
| 1292 | PHC_THREAD_LOCAL(bool)__thread ::mozilla::detail::ThreadLocal< bool, ::mozilla:: detail::ThreadLocalNativeStorage> PHC::tlsIsDisabled; |
| 1293 | PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> PHC::tlsAllocDelay; |
| 1294 | Atomic<Delay, ReleaseAcquire> PHC::sAllocDelay; |
| 1295 | PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> PHC::tlsLastDelay; |
| 1296 | |
| 1297 | // This must be defined after the PHC class. |
| 1298 | PHCRegion::PHCRegion() |
| 1299 | : mPagesStart(AllocAllPages()), mPagesLimit(mPagesStart + kAllPagesSize) { |
| 1300 | LOG("AllocAllPages at %p..%p\n", mPagesStart, mPagesLimit); |
| 1301 | } |
| 1302 | |
| 1303 | // When PHC wants to crash we first have to unlock so that the crash reporter |
| 1304 | // can call into PHC to lockup its pointer. That also means that before calling |
| 1305 | // PHCCrash please ensure that state is consistent. Because this can report an |
| 1306 | // arbitrary string, use of it must be reviewed by Firefox data stewards. |
| 1307 | static void PHCCrash(PHCLock, const char* aMessage) |
| 1308 | MOZ_REQUIRES(PHC::sPHC->mMutex)__attribute__((exclusive_locks_required(PHC::sPHC->mMutex) )) { |
| 1309 | PHC::sPHC->mMutex.Unlock(); |
| 1310 | MOZ_CRASH_UNSAFE(aMessage)MOZ_Crash("/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1310, aMessage); |
| 1311 | } |
| 1312 | |
| 1313 | class AutoDisableOnCurrentThread { |
| 1314 | public: |
| 1315 | AutoDisableOnCurrentThread(const AutoDisableOnCurrentThread&) = delete; |
| 1316 | |
| 1317 | const AutoDisableOnCurrentThread& operator=( |
| 1318 | const AutoDisableOnCurrentThread&) = delete; |
| 1319 | |
| 1320 | explicit AutoDisableOnCurrentThread() { PHC::DisableOnCurrentThread(); } |
| 1321 | ~AutoDisableOnCurrentThread() { PHC::sPHC->EnableOnCurrentThread(); } |
| 1322 | }; |
| 1323 | |
| 1324 | //--------------------------------------------------------------------------- |
| 1325 | // Initialisation |
| 1326 | //--------------------------------------------------------------------------- |
| 1327 | |
| 1328 | // WARNING: this function runs *very* early -- before all static initializers |
| 1329 | // have run. For this reason, non-scalar globals (sRegion, sPHC) are allocated |
| 1330 | // dynamically (so we can guarantee their construction in this function) rather |
| 1331 | // than statically. |
| 1332 | static bool phc_init() { |
| 1333 | if (GetKernelPageSize() != kPageSize) { |
| 1334 | return false; |
| 1335 | } |
| 1336 | |
| 1337 | // sRegion and sPHC are never freed. They live for the life of the process. |
| 1338 | PHC::sRegion = InfallibleAllocPolicy::new_<PHCRegion>(); |
| 1339 | |
| 1340 | PHC::sPHC = InfallibleAllocPolicy::new_<PHC>(); |
| 1341 | |
| 1342 | #ifndef XP_WIN |
| 1343 | // Avoid deadlocks when forking by acquiring our state lock prior to forking |
| 1344 | // and releasing it after forking. See |LogAlloc|'s |phc_init| for |
| 1345 | // in-depth details. |
| 1346 | pthread_atfork(PHC::prefork, PHC::postfork_parent, PHC::postfork_child); |
| 1347 | #endif |
| 1348 | |
| 1349 | return true; |
| 1350 | } |
| 1351 | |
| 1352 | static inline bool maybe_init() { |
| 1353 | // This runs on hot paths and we can save some memory accesses by using sPHC |
| 1354 | // to test if we've already initialised PHC successfully. |
| 1355 | if (MOZ_UNLIKELY(!PHC::sPHC)(__builtin_expect(!!(!PHC::sPHC), 0))) { |
| 1356 | // The lambda will only be called once and is thread safe. |
| 1357 | static bool sInitSuccess = []() { return phc_init(); }(); |
| 1358 | return sInitSuccess; |
| 1359 | } |
| 1360 | |
| 1361 | return true; |
| 1362 | } |
| 1363 | |
| 1364 | //--------------------------------------------------------------------------- |
| 1365 | // Page allocation operations |
| 1366 | //--------------------------------------------------------------------------- |
| 1367 | |
| 1368 | // This is the hot-path for testing if we should make a PHC allocation, it |
| 1369 | // should be inlined into the caller while the remainder of the tests that are |
| 1370 | // in MaybePageAlloc need not be inlined. |
| 1371 | static MOZ_ALWAYS_INLINEinline bool ShouldPageAllocHot(size_t aReqSize) { |
| 1372 | if (MOZ_UNLIKELY(!maybe_init())(__builtin_expect(!!(!maybe_init()), 0))) { |
| 1373 | return false; |
| 1374 | } |
| 1375 | |
| 1376 | if (MOZ_UNLIKELY(aReqSize > kPageSize)(__builtin_expect(!!(aReqSize > kPageSize), 0))) { |
| 1377 | return false; |
| 1378 | } |
| 1379 | |
| 1380 | // Decrement the delay. If it's zero, we do a page allocation and reset the |
| 1381 | // delay to a random number. |
| 1382 | if (MOZ_LIKELY(!PHC::DecrementDelay())(__builtin_expect(!!(!PHC::DecrementDelay()), 1))) { |
| 1383 | return false; |
| 1384 | } |
| 1385 | |
| 1386 | return true; |
| 1387 | } |
| 1388 | |
| 1389 | static void LogNoAlloc(size_t aReqSize, size_t aAlignment, |
| 1390 | Delay newAllocDelay) { |
| 1391 | // No pages are available, or VirtualAlloc/mprotect failed. |
| 1392 | #if PHC_LOGGING0 |
| 1393 | phc::PHCStats stats = PHC::sPHC->GetPageStats(lock); |
| 1394 | #endif |
| 1395 | LOG("No PageAlloc(%zu, %zu), sAllocDelay <- %zu, fullness %zu/%zu/%zu, " |
| 1396 | "hits %zu/%zu (%zu%%)\n", |
| 1397 | aReqSize, aAlignment, size_t(newAllocDelay), stats.mSlotsAllocated, |
| 1398 | stats.mSlotsFreed, kNumAllocPages, PHC::sPHC->PageAllocHits(lock), |
| 1399 | PHC::sPHC->PageAllocAttempts(lock), PHC::sPHC->PageAllocHitRate(lock)); |
| 1400 | } |
| 1401 | |
| 1402 | // Attempt a page allocation if the time and the size are right. Allocated |
| 1403 | // memory is zeroed if aZero is true. On failure, the caller should attempt a |
| 1404 | // normal allocation via MozJemalloc. Can be called in a context where |
| 1405 | // PHC::mMutex is locked. |
| 1406 | static void* MaybePageAlloc(const Maybe<arena_id_t>& aArenaId, size_t aReqSize, |
| 1407 | size_t aAlignment, bool aZero) { |
| 1408 | MOZ_ASSERT(IsPowerOfTwo(aAlignment))do { static_assert( mozilla::detail::AssertionConditionType< decltype(IsPowerOfTwo(aAlignment))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(IsPowerOfTwo(aAlignment)))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("IsPowerOfTwo(aAlignment)" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1408); AnnotateMozCrashReason("MOZ_ASSERT" "(" "IsPowerOfTwo(aAlignment)" ")"); do { *((volatile int*)__null) = 1408; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1409 | MOZ_ASSERT(PHC::sPHC)do { static_assert( mozilla::detail::AssertionConditionType< decltype(PHC::sPHC)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(PHC::sPHC))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("PHC::sPHC", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1409); AnnotateMozCrashReason("MOZ_ASSERT" "(" "PHC::sPHC" ")" ); do { *((volatile int*)__null) = 1409; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1410 | if (!PHC::sPHC->ShouldMakeNewAllocations()) { |
| 1411 | // Reset the allocation delay so that we take the fast path most of the |
| 1412 | // time. Rather than take the lock and use the RNG which are unnecessary |
| 1413 | // when PHC is disabled, instead set the delay to a reasonably high number, |
| 1414 | // the default average first allocation delay. This is reset when PHC is |
| 1415 | // re-enabled anyway. |
| 1416 | PHC::ForceSetNewAllocDelay(kDelayResetWhenDisabled); |
| 1417 | return nullptr; |
| 1418 | } |
| 1419 | |
| 1420 | if (PHC::IsDisabledOnCurrentThread()) { |
| 1421 | // We don't reset sAllocDelay since that might affect other threads. We |
| 1422 | // assume this is okay because either this thread will be re-enabled after |
| 1423 | // less than DELAY_MAX allocations or that there are other active threads |
| 1424 | // that will reset sAllocDelay. We do reset our local delay which will |
| 1425 | // cause this thread to "back off" from updating sAllocDelay on future |
| 1426 | // allocations. |
| 1427 | PHC::ResetLocalAllocDelay(kDelayBackoffAmount); |
| 1428 | return nullptr; |
| 1429 | } |
| 1430 | |
| 1431 | // Disable on this thread *before* getting the stack trace. |
| 1432 | AutoDisableOnCurrentThread disable; |
| 1433 | |
| 1434 | // Get the stack trace *before* locking the mutex. If we return nullptr then |
| 1435 | // it was a waste, but it's not so frequent, and doing a stack walk while |
| 1436 | // the mutex is locked is problematic (see the big comment on |
| 1437 | // StackTrace::Fill() for details). |
| 1438 | StackTrace allocStack; |
| 1439 | allocStack.Fill(); |
| 1440 | |
| 1441 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 1442 | |
| 1443 | Time now = PHC::Now(); |
| 1444 | |
| 1445 | Delay newAllocDelay = Rnd64ToDelay(PHC::sPHC->GetAvgAllocDelay(lock), |
| 1446 | PHC::sPHC->Random64(lock)); |
| 1447 | if (!PHC::sPHC->SetNewAllocDelay(newAllocDelay)) { |
| 1448 | return nullptr; |
| 1449 | } |
| 1450 | |
| 1451 | // Pages are allocated from a free list populated in order of when they're |
| 1452 | // freed. If the page at the head of the list is too recently freed to be |
| 1453 | // reused then no other pages on the list will be either. |
| 1454 | |
| 1455 | Maybe<uintptr_t> mb_index = PHC::sPHC->PopNextFreeIfAllocatable(lock, now); |
| 1456 | if (!mb_index) { |
| 1457 | PHC::sPHC->IncPageAllocMisses(lock); |
| 1458 | LogNoAlloc(aReqSize, aAlignment, newAllocDelay); |
| 1459 | return nullptr; |
| 1460 | } |
| 1461 | uintptr_t index = mb_index.value(); |
| 1462 | |
| 1463 | #if PHC_LOGGING0 |
| 1464 | Time lifetime = 0; |
| 1465 | #endif |
| 1466 | uint8_t* pagePtr = PHC::sRegion->AllocPagePtr(index); |
| 1467 | MOZ_ASSERT(pagePtr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(pagePtr)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(pagePtr))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("pagePtr", "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1467); AnnotateMozCrashReason("MOZ_ASSERT" "(" "pagePtr" ")" ); do { *((volatile int*)__null) = 1467; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1468 | bool ok = |
| 1469 | #ifdef XP_WIN |
| 1470 | !!VirtualAlloc(pagePtr, kPageSize, MEM_COMMIT, PAGE_READWRITE); |
| 1471 | #else |
| 1472 | mprotect(pagePtr, kPageSize, PROT_READ0x1 | PROT_WRITE0x2) == 0; |
| 1473 | #endif |
| 1474 | |
| 1475 | if (!ok) { |
| 1476 | PHC::sPHC->UnpopNextFree(lock, index); |
| 1477 | PHC::sPHC->IncPageAllocMisses(lock); |
| 1478 | LogNoAlloc(aReqSize, aAlignment, newAllocDelay); |
| 1479 | return nullptr; |
| 1480 | } |
| 1481 | |
| 1482 | size_t usableSize = MozJemalloc::malloc_good_size(aReqSize); |
| 1483 | MOZ_ASSERT(usableSize > 0)do { static_assert( mozilla::detail::AssertionConditionType< decltype(usableSize > 0)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(usableSize > 0))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("usableSize > 0" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1483); AnnotateMozCrashReason("MOZ_ASSERT" "(" "usableSize > 0" ")"); do { *((volatile int*)__null) = 1483; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1484 | |
| 1485 | // Put the allocation as close to the end of the page as possible, |
| 1486 | // allowing for alignment requirements. |
| 1487 | uint8_t* ptr = pagePtr + kPageSize - usableSize; |
| 1488 | if (aAlignment != 1) { |
| 1489 | ptr = reinterpret_cast<uint8_t*>( |
| 1490 | (reinterpret_cast<uintptr_t>(ptr) & ~(aAlignment - 1))); |
| 1491 | } |
| 1492 | |
| 1493 | #if PHC_LOGGING0 |
| 1494 | Time then = PHC::sPHC->GetFreeTime(i); |
| 1495 | lifetime = then != 0 ? now - then : 0; |
| 1496 | #endif |
| 1497 | |
| 1498 | PHC::sPHC->SetPageInUse(lock, index, aArenaId, ptr, allocStack); |
| 1499 | |
| 1500 | if (aZero) { |
| 1501 | memset(ptr, 0, usableSize); |
| 1502 | } else { |
| 1503 | #ifdef DEBUG1 |
| 1504 | memset(ptr, kAllocJunk, usableSize); |
| 1505 | #endif |
| 1506 | } |
| 1507 | |
| 1508 | PHC::sPHC->IncPageAllocHits(lock); |
| 1509 | #if PHC_LOGGING0 |
| 1510 | phc::PHCStats stats = PHC::sPHC->GetPageStats(lock); |
| 1511 | #endif |
| 1512 | LOG("PageAlloc(%zu, %zu) -> %p[%zu]/%p (%zu) (z%zu), sAllocDelay <- %zu, " |
| 1513 | "fullness %zu/%zu/%zu, hits %zu/%zu (%zu%%), lifetime %zu\n", |
| 1514 | aReqSize, aAlignment, pagePtr, i, ptr, usableSize, size_t(newAllocDelay), |
| 1515 | size_t(PHC::SharedAllocDelay()), stats.mSlotsAllocated, stats.mSlotsFreed, |
| 1516 | kNumAllocPages, PHC::sPHC->PageAllocHits(lock), |
| 1517 | PHC::sPHC->PageAllocAttempts(lock), PHC::sPHC->PageAllocHitRate(lock), |
| 1518 | lifetime); |
| 1519 | |
| 1520 | return ptr; |
| 1521 | } |
| 1522 | |
| 1523 | static void FreePage(PHCLock aLock, uintptr_t aIndex, |
| 1524 | const Maybe<arena_id_t>& aArenaId, |
| 1525 | const StackTrace& aFreeStack, Delay aReuseDelay) |
| 1526 | MOZ_REQUIRES(PHC::sPHC->mMutex)__attribute__((exclusive_locks_required(PHC::sPHC->mMutex) )) { |
| 1527 | void* pagePtr = PHC::sRegion->AllocPagePtr(aIndex); |
| 1528 | |
| 1529 | #ifdef XP_WIN |
| 1530 | if (!VirtualFree(pagePtr, kPageSize, MEM_DECOMMIT)) { |
| 1531 | PHCCrash(aLock, "VirtualFree failed"); |
| 1532 | } |
| 1533 | #else |
| 1534 | if (mmap_mmap(pagePtr, kPageSize, PROT_NONE0x0, MAP_FIXED0x10 | MAP_PRIVATE0x02 | MAP_ANON0x20, |
| 1535 | -1, 0) == MAP_FAILED((void *) -1)) { |
| 1536 | PHCCrash(aLock, "mmap failed"); |
| 1537 | } |
| 1538 | #endif |
| 1539 | |
| 1540 | PHC::sPHC->SetPageFreed(aLock, aIndex, aArenaId, aFreeStack, aReuseDelay); |
| 1541 | } |
| 1542 | |
| 1543 | //--------------------------------------------------------------------------- |
| 1544 | // replace-malloc machinery |
| 1545 | //--------------------------------------------------------------------------- |
| 1546 | |
| 1547 | // This handles malloc, moz_arena_malloc, and realloc-with-a-nullptr. |
| 1548 | MOZ_ALWAYS_INLINEinline static void* PageMalloc(const Maybe<arena_id_t>& aArenaId, |
| 1549 | size_t aReqSize) { |
| 1550 | void* ptr = ShouldPageAllocHot(aReqSize) |
| 1551 | // The test on aArenaId here helps the compiler optimise away |
| 1552 | // the construction of Nothing() in the caller. |
| 1553 | ? MaybePageAlloc(aArenaId.isSome() ? aArenaId : Nothing(), |
| 1554 | aReqSize, /* aAlignment */ 1, |
| 1555 | /* aZero */ false) |
| 1556 | : nullptr; |
| 1557 | return ptr ? ptr |
| 1558 | : (aArenaId.isSome() |
| 1559 | ? MozJemalloc::moz_arena_malloc(*aArenaId, aReqSize) |
| 1560 | : MozJemalloc::malloc(aReqSize)); |
| 1561 | } |
| 1562 | |
| 1563 | inline void* MozJemallocPHC::malloc(size_t aReqSize) { |
| 1564 | return PageMalloc(Nothing(), aReqSize); |
| 1565 | } |
| 1566 | |
| 1567 | static Delay ReuseDelay(PHCLock aLock) { |
| 1568 | Delay avg_reuse_delay = PHC::sPHC->GetAvgPageReuseDelay(aLock); |
| 1569 | return (avg_reuse_delay / 2) + |
| 1570 | Rnd64ToDelay(avg_reuse_delay / 2, PHC::sPHC->Random64(aLock)); |
| 1571 | } |
| 1572 | |
| 1573 | // This handles both calloc and moz_arena_calloc. |
| 1574 | MOZ_ALWAYS_INLINEinline static void* PageCalloc(const Maybe<arena_id_t>& aArenaId, |
| 1575 | size_t aNum, size_t aReqSize) { |
| 1576 | CheckedInt<size_t> checkedSize = CheckedInt<size_t>(aNum) * aReqSize; |
| 1577 | if (!checkedSize.isValid()) { |
| 1578 | return nullptr; |
| 1579 | } |
| 1580 | |
| 1581 | void* ptr = ShouldPageAllocHot(checkedSize.value()) |
| 1582 | // The test on aArenaId here helps the compiler optimise away |
| 1583 | // the construction of Nothing() in the caller. |
| 1584 | ? MaybePageAlloc(aArenaId.isSome() ? aArenaId : Nothing(), |
| 1585 | checkedSize.value(), /* aAlignment */ 1, |
| 1586 | /* aZero */ true) |
| 1587 | : nullptr; |
| 1588 | return ptr ? ptr |
| 1589 | : (aArenaId.isSome() |
| 1590 | ? MozJemalloc::moz_arena_calloc(*aArenaId, aNum, aReqSize) |
| 1591 | : MozJemalloc::calloc(aNum, aReqSize)); |
| 1592 | } |
| 1593 | |
| 1594 | inline void* MozJemallocPHC::calloc(size_t aNum, size_t aReqSize) { |
| 1595 | return PageCalloc(Nothing(), aNum, aReqSize); |
| 1596 | } |
| 1597 | |
| 1598 | // This function handles both realloc and moz_arena_realloc. |
| 1599 | // |
| 1600 | // As always, realloc is complicated, and doubly so when there are two |
| 1601 | // different kinds of allocations in play. Here are the possible transitions, |
| 1602 | // and what we do in practice. |
| 1603 | // |
| 1604 | // - normal-to-normal: This is straightforward and obviously necessary. |
| 1605 | // |
| 1606 | // - normal-to-page: This is disallowed because it would require getting the |
| 1607 | // arenaId of the normal allocation, which isn't possible in non-DEBUG builds |
| 1608 | // for security reasons. |
| 1609 | // |
| 1610 | // - page-to-page: This is done whenever possible, i.e. whenever the new size |
| 1611 | // is less than or equal to 4 KiB. This choice counterbalances the |
| 1612 | // disallowing of normal-to-page allocations, in order to avoid biasing |
| 1613 | // towards or away from page allocations. It always occurs in-place. |
| 1614 | // |
| 1615 | // - page-to-normal: this is done only when necessary, i.e. only when the new |
| 1616 | // size is greater than 4 KiB. This choice naturally flows from the |
| 1617 | // prior choice on page-to-page transitions. |
| 1618 | // |
| 1619 | // In summary: realloc doesn't change the allocation kind unless it must. |
| 1620 | // |
| 1621 | // This function may return: |
| 1622 | // - Some(pointer) when PHC handled the reallocation. |
| 1623 | // - Some(nullptr) when PHC should have handled a page-to-normal transition |
| 1624 | // but couldn't because of OOM. |
| 1625 | // - Nothing() when PHC is disabled or the original allocation was not |
| 1626 | // under PHC. |
| 1627 | MOZ_ALWAYS_INLINEinline static Maybe<void*> MaybePageRealloc( |
| 1628 | const Maybe<arena_id_t>& aArenaId, void* aOldPtr, size_t aNewSize) { |
| 1629 | if (!aOldPtr) { |
| 1630 | // Null pointer. Treat like malloc(aNewSize). |
| 1631 | return Some(PageMalloc(aArenaId, aNewSize)); |
| 1632 | } |
| 1633 | |
| 1634 | if (!maybe_init()) { |
| 1635 | return Nothing(); |
| 1636 | } |
| 1637 | |
| 1638 | PtrKind pk = PHC::sRegion->PtrKind(aOldPtr); |
| 1639 | if (pk.IsNothing()) { |
| 1640 | // A normal-to-normal transition. |
| 1641 | return Nothing(); |
| 1642 | } |
| 1643 | |
| 1644 | if (pk.IsGuardPage()) { |
| 1645 | PHC::CrashOnGuardPage(aOldPtr); |
| 1646 | } |
| 1647 | |
| 1648 | // At this point we know we have an allocation page. |
| 1649 | uintptr_t index = pk.AllocPageIndex(); |
| 1650 | |
| 1651 | // A page-to-something transition. |
| 1652 | PHC::sPHC->AdvanceNow(PHC::LocalAllocDelay()); |
| 1653 | |
| 1654 | // Note that `disable` has no effect unless it is emplaced below. |
| 1655 | Maybe<AutoDisableOnCurrentThread> disable; |
| 1656 | // Get the stack trace *before* locking the mutex. |
| 1657 | StackTrace stack; |
| 1658 | if (PHC::IsDisabledOnCurrentThread()) { |
| 1659 | // PHC is disabled on this thread. Leave the stack empty. |
| 1660 | } else { |
| 1661 | // Disable on this thread *before* getting the stack trace. |
| 1662 | disable.emplace(); |
| 1663 | stack.Fill(); |
| 1664 | } |
| 1665 | |
| 1666 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 1667 | |
| 1668 | // Check for realloc() of a freed block. |
| 1669 | PHC::sPHC->EnsureValidAndInUse(lock, aOldPtr, index); |
| 1670 | |
| 1671 | if (aNewSize <= kPageSize && PHC::sPHC->ShouldMakeNewAllocations()) { |
| 1672 | // A page-to-page transition. Just keep using the page allocation. We do |
| 1673 | // this even if the thread is disabled, because it doesn't create a new |
| 1674 | // page allocation. Note that ResizePageInUse() checks aArenaId. |
| 1675 | // |
| 1676 | // Move the bytes with memmove(), because the old allocation and the new |
| 1677 | // allocation overlap. Move the usable size rather than the requested size, |
| 1678 | // because the user might have used malloc_usable_size() and filled up the |
| 1679 | // usable size. |
| 1680 | size_t oldUsableSize = PHC::sPHC->PageUsableSize(lock, index); |
| 1681 | size_t newUsableSize = MozJemalloc::malloc_good_size(aNewSize); |
| 1682 | uint8_t* pagePtr = PHC::sRegion->AllocPagePtr(index); |
| 1683 | uint8_t* newPtr = pagePtr + kPageSize - newUsableSize; |
| 1684 | memmove(newPtr, aOldPtr, std::min(oldUsableSize, aNewSize)); |
| 1685 | PHC::sPHC->ResizePageInUse(lock, index, aArenaId, newPtr, stack); |
| 1686 | LOG("PageRealloc-Reuse(%p, %zu) -> %p\n", aOldPtr, aNewSize, newPtr); |
| 1687 | return Some(newPtr); |
| 1688 | } |
| 1689 | |
| 1690 | // A page-to-normal transition (with the new size greater than page-sized). |
| 1691 | // (Note that aArenaId is checked below.) |
| 1692 | void* newPtr; |
| 1693 | if (aArenaId.isSome()) { |
| 1694 | newPtr = MozJemalloc::moz_arena_malloc(*aArenaId, aNewSize); |
| 1695 | } else { |
| 1696 | Maybe<arena_id_t> oldArenaId = PHC::sPHC->PageArena(lock, index); |
| 1697 | newPtr = (oldArenaId.isSome() |
| 1698 | ? MozJemalloc::moz_arena_malloc(*oldArenaId, aNewSize) |
| 1699 | : MozJemalloc::malloc(aNewSize)); |
| 1700 | } |
| 1701 | if (!newPtr) { |
| 1702 | return Some(nullptr); |
| 1703 | } |
| 1704 | |
| 1705 | Delay reuseDelay = ReuseDelay(lock); |
| 1706 | |
| 1707 | // Copy the usable size rather than the requested size, because the user |
| 1708 | // might have used malloc_usable_size() and filled up the usable size. Note |
| 1709 | // that FreePage() checks aArenaId (via SetPageFreed()). |
| 1710 | size_t oldUsableSize = PHC::sPHC->PageUsableSize(lock, index); |
| 1711 | memcpy(newPtr, aOldPtr, std::min(oldUsableSize, aNewSize)); |
| 1712 | FreePage(lock, index, aArenaId, stack, reuseDelay); |
| 1713 | LOG("PageRealloc-Free(%p[%zu], %zu) -> %p, %zu delay, reuse at ~%zu\n", |
| 1714 | aOldPtr, index, aNewSize, newPtr, size_t(reuseDelay), |
| 1715 | size_t(PHC::Now()) + reuseDelay); |
| 1716 | |
| 1717 | return Some(newPtr); |
| 1718 | } |
| 1719 | |
| 1720 | MOZ_ALWAYS_INLINEinline static void* PageRealloc(const Maybe<arena_id_t>& aArenaId, |
| 1721 | void* aOldPtr, size_t aNewSize) { |
| 1722 | Maybe<void*> ptr = MaybePageRealloc(aArenaId, aOldPtr, aNewSize); |
| 1723 | |
| 1724 | return ptr.isSome() |
| 1725 | ? *ptr |
| 1726 | : (aArenaId.isSome() ? MozJemalloc::moz_arena_realloc( |
| 1727 | *aArenaId, aOldPtr, aNewSize) |
| 1728 | : MozJemalloc::realloc(aOldPtr, aNewSize)); |
| 1729 | } |
| 1730 | |
| 1731 | inline void* MozJemallocPHC::realloc(void* aOldPtr, size_t aNewSize) { |
| 1732 | return PageRealloc(Nothing(), aOldPtr, aNewSize); |
| 1733 | } |
| 1734 | |
| 1735 | // This handles both free and moz_arena_free. |
| 1736 | static void DoPageFree(const Maybe<arena_id_t>& aArenaId, void* aPtr) { |
| 1737 | PtrKind pk = PHC::sRegion->PtrKind(aPtr); |
| 1738 | if (pk.IsGuardPage()) { |
| 1739 | PHC::CrashOnGuardPage(aPtr); |
| 1740 | } |
| 1741 | |
| 1742 | // At this point we know we have an allocation page. |
| 1743 | PHC::sPHC->AdvanceNow(PHC::LocalAllocDelay()); |
| 1744 | uintptr_t index = pk.AllocPageIndex(); |
| 1745 | |
| 1746 | // Note that `disable` has no effect unless it is emplaced below. |
| 1747 | Maybe<AutoDisableOnCurrentThread> disable; |
| 1748 | // Get the stack trace *before* locking the mutex. |
| 1749 | StackTrace freeStack; |
| 1750 | if (PHC::IsDisabledOnCurrentThread()) { |
| 1751 | // PHC is disabled on this thread. Leave the stack empty. |
| 1752 | } else { |
| 1753 | // Disable on this thread *before* getting the stack trace. |
| 1754 | disable.emplace(); |
| 1755 | freeStack.Fill(); |
| 1756 | } |
| 1757 | |
| 1758 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 1759 | |
| 1760 | // Check for a double-free. |
| 1761 | PHC::sPHC->EnsureValidAndInUse(lock, aPtr, index); |
| 1762 | |
| 1763 | // Note that FreePage() checks aArenaId (via SetPageFreed()). |
| 1764 | Delay reuseDelay = ReuseDelay(lock); |
| 1765 | FreePage(lock, index, aArenaId, freeStack, reuseDelay); |
| 1766 | |
| 1767 | #if PHC_LOGGING0 |
| 1768 | phc::PHCStats stats = PHC::sPHC->GetPageStats(lock); |
| 1769 | #endif |
| 1770 | LOG("PageFree(%p[%zu]), %zu delay, reuse at ~%zu, fullness %zu/%zu/%zu\n", |
| 1771 | aPtr, index, size_t(reuseDelay), size_t(PHC::Now()) + reuseDelay, |
| 1772 | stats.mSlotsAllocated, stats.mSlotsFreed, kNumAllocPages); |
| 1773 | } |
| 1774 | |
| 1775 | MOZ_ALWAYS_INLINEinline static bool FastIsPHCPtr(void* aPtr) { |
| 1776 | if (MOZ_UNLIKELY(!maybe_init())(__builtin_expect(!!(!maybe_init()), 0))) { |
| 1777 | return false; |
| 1778 | } |
| 1779 | |
| 1780 | PtrKind pk = PHC::sRegion->PtrKind(aPtr); |
| 1781 | return !pk.IsNothing(); |
| 1782 | } |
| 1783 | |
| 1784 | MOZ_ALWAYS_INLINEinline static void PageFree(const Maybe<arena_id_t>& aArenaId, |
| 1785 | void* aPtr) { |
| 1786 | if (MOZ_UNLIKELY(FastIsPHCPtr(aPtr))(__builtin_expect(!!(FastIsPHCPtr(aPtr)), 0))) { |
| 1787 | // The tenery expression here helps the compiler optimise away the |
| 1788 | // construction of Nothing() in the caller. |
| 1789 | DoPageFree(aArenaId.isSome() ? aArenaId : Nothing(), aPtr); |
| 1790 | return; |
| 1791 | } |
| 1792 | |
| 1793 | aArenaId.isSome() ? MozJemalloc::moz_arena_free(*aArenaId, aPtr) |
| 1794 | : MozJemalloc::free(aPtr); |
| 1795 | } |
| 1796 | |
| 1797 | inline void MozJemallocPHC::free(void* aPtr) { PageFree(Nothing(), aPtr); } |
| 1798 | |
| 1799 | // This handles memalign and moz_arena_memalign. |
| 1800 | MOZ_ALWAYS_INLINEinline static void* PageMemalign(const Maybe<arena_id_t>& aArenaId, |
| 1801 | size_t aAlignment, |
| 1802 | size_t aReqSize) { |
| 1803 | MOZ_RELEASE_ASSERT(IsPowerOfTwo(aAlignment))do { static_assert( mozilla::detail::AssertionConditionType< decltype(IsPowerOfTwo(aAlignment))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(IsPowerOfTwo(aAlignment)))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("IsPowerOfTwo(aAlignment)" , "/var/lib/jenkins/workspace/firefox-scan-build/memory/build/PHC.cpp" , 1803); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "IsPowerOfTwo(aAlignment)" ")"); do { *((volatile int*)__null) = 1803; __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
| 1804 | |
| 1805 | // PHC can't satisfy an alignment greater than a page size, so fall back to |
| 1806 | // mozjemalloc in that case. |
| 1807 | void* ptr = nullptr; |
| 1808 | if (ShouldPageAllocHot(aReqSize) && aAlignment <= kPageSize) { |
| 1809 | // The test on aArenaId here helps the compiler optimise away |
| 1810 | // the construction of Nothing() in the caller. |
| 1811 | ptr = MaybePageAlloc(aArenaId.isSome() ? aArenaId : Nothing(), aReqSize, |
| 1812 | aAlignment, /* aZero */ false); |
| 1813 | } |
| 1814 | return ptr ? ptr |
| 1815 | : (aArenaId.isSome() |
| 1816 | ? MozJemalloc::moz_arena_memalign(*aArenaId, aAlignment, |
| 1817 | aReqSize) |
| 1818 | : MozJemalloc::memalign(aAlignment, aReqSize)); |
| 1819 | } |
| 1820 | |
| 1821 | inline void* MozJemallocPHC::memalign(size_t aAlignment, size_t aReqSize) { |
| 1822 | return PageMemalign(Nothing(), aAlignment, aReqSize); |
| 1823 | } |
| 1824 | |
| 1825 | inline size_t MozJemallocPHC::malloc_usable_size(usable_ptr_t aPtr) { |
| 1826 | if (!maybe_init()) { |
| 1827 | return MozJemalloc::malloc_usable_size(aPtr); |
| 1828 | } |
| 1829 | |
| 1830 | PtrKind pk = PHC::sRegion->PtrKind(aPtr); |
| 1831 | if (pk.IsNothing()) { |
| 1832 | // Not a page allocation. Measure it normally. |
| 1833 | return MozJemalloc::malloc_usable_size(aPtr); |
| 1834 | } |
| 1835 | |
| 1836 | if (pk.IsGuardPage()) { |
| 1837 | PHC::CrashOnGuardPage(const_cast<void*>(aPtr)); |
| 1838 | } |
| 1839 | |
| 1840 | // At this point we know aPtr lands within an allocation page, due to the |
| 1841 | // math done in the PtrKind constructor. But if aPtr points to memory |
| 1842 | // before the base address of the allocation, we return 0. |
| 1843 | uintptr_t index = pk.AllocPageIndex(); |
| 1844 | |
| 1845 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 1846 | |
| 1847 | void* pageBaseAddr = PHC::sPHC->AllocPageBaseAddr(lock, index); |
| 1848 | |
| 1849 | if (MOZ_UNLIKELY(aPtr < pageBaseAddr)(__builtin_expect(!!(aPtr < pageBaseAddr), 0))) { |
| 1850 | return 0; |
| 1851 | } |
| 1852 | |
| 1853 | return PHC::sPHC->PageUsableSize(lock, index); |
| 1854 | } |
| 1855 | |
| 1856 | static size_t metadata_size() { |
| 1857 | return MozJemalloc::malloc_usable_size(PHC::sRegion) + |
| 1858 | MozJemalloc::malloc_usable_size(PHC::sPHC); |
| 1859 | } |
| 1860 | |
| 1861 | inline void MozJemallocPHC::jemalloc_stats_internal( |
| 1862 | jemalloc_stats_t* aStats, jemalloc_bin_stats_t* aBinStats) { |
| 1863 | MozJemalloc::jemalloc_stats_internal(aStats, aBinStats); |
| 1864 | |
| 1865 | if (!maybe_init()) { |
| 1866 | // If we're not initialised, then we're not using any additional memory and |
| 1867 | // have nothing to add to the report. |
| 1868 | return; |
| 1869 | } |
| 1870 | |
| 1871 | // We allocate our memory from jemalloc so it has already counted our memory |
| 1872 | // usage within "mapped" and "allocated", we must subtract the memory we |
| 1873 | // allocated from jemalloc from allocated before adding in only the parts that |
| 1874 | // we have allocated out to Firefox. |
| 1875 | |
| 1876 | aStats->allocated -= kAllPagesJemallocSize; |
| 1877 | |
| 1878 | size_t allocated = 0; |
| 1879 | { |
| 1880 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 1881 | |
| 1882 | // Add usable space of in-use allocations to `allocated`. |
| 1883 | for (size_t i = 0; i < kNumAllocPages; i++) { |
| 1884 | if (PHC::sPHC->IsPageInUse(lock, i)) { |
| 1885 | allocated += PHC::sPHC->PageUsableSize(lock, i); |
| 1886 | } |
| 1887 | } |
| 1888 | } |
| 1889 | aStats->allocated += allocated; |
| 1890 | |
| 1891 | // guards is the gap between `allocated` and `mapped`. In some ways this |
| 1892 | // almost fits into aStats->wasted since it feels like wasted memory. However |
| 1893 | // wasted should only include committed memory and these guard pages are |
| 1894 | // uncommitted. Therefore we don't include it anywhere. |
| 1895 | // size_t guards = mapped - allocated; |
| 1896 | |
| 1897 | // aStats.page_cache and aStats.bin_unused are left unchanged because PHC |
| 1898 | // doesn't have anything corresponding to those. |
| 1899 | |
| 1900 | // The metadata is stored in normal heap allocations, so they're measured by |
| 1901 | // mozjemalloc as `allocated`. Move them into `bookkeeping`. |
| 1902 | // They're also reported under explicit/heap-overhead/phc/fragmentation in |
| 1903 | // about:memory. |
| 1904 | size_t bookkeeping = metadata_size(); |
| 1905 | aStats->allocated -= bookkeeping; |
| 1906 | aStats->bookkeeping += bookkeeping; |
| 1907 | } |
| 1908 | |
| 1909 | inline void MozJemallocPHC::jemalloc_ptr_info(const void* aPtr, |
| 1910 | jemalloc_ptr_info_t* aInfo) { |
| 1911 | if (!maybe_init()) { |
| 1912 | return MozJemalloc::jemalloc_ptr_info(aPtr, aInfo); |
| 1913 | } |
| 1914 | |
| 1915 | // We need to implement this properly, because various code locations do |
| 1916 | // things like checking that allocations are in the expected arena. |
| 1917 | PtrKind pk = PHC::sRegion->PtrKind(aPtr); |
| 1918 | if (pk.IsNothing()) { |
| 1919 | // Not a page allocation. |
| 1920 | return MozJemalloc::jemalloc_ptr_info(aPtr, aInfo); |
| 1921 | } |
| 1922 | |
| 1923 | if (pk.IsGuardPage()) { |
| 1924 | // Treat a guard page as unknown because there's no better alternative. |
| 1925 | *aInfo = {TagUnknown, nullptr, 0, 0}; |
| 1926 | return; |
| 1927 | } |
| 1928 | |
| 1929 | // At this point we know we have an allocation page. |
| 1930 | uintptr_t index = pk.AllocPageIndex(); |
| 1931 | |
| 1932 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 1933 | |
| 1934 | PHC::sPHC->FillJemallocPtrInfo(lock, aPtr, index, aInfo); |
| 1935 | #if DEBUG1 |
| 1936 | LOG("JemallocPtrInfo(%p[%zu]) -> {%zu, %p, %zu, %zu}\n", aPtr, index, |
| 1937 | size_t(aInfo->tag), aInfo->addr, aInfo->size, aInfo->arenaId); |
| 1938 | #else |
| 1939 | LOG("JemallocPtrInfo(%p[%zu]) -> {%zu, %p, %zu}\n", aPtr, index, |
| 1940 | size_t(aInfo->tag), aInfo->addr, aInfo->size); |
| 1941 | #endif |
| 1942 | } |
| 1943 | |
| 1944 | inline void* MozJemallocPHC::moz_arena_malloc(arena_id_t aArenaId, |
| 1945 | size_t aReqSize) { |
| 1946 | return PageMalloc(Some(aArenaId), aReqSize); |
| 1947 | } |
| 1948 | |
| 1949 | inline void* MozJemallocPHC::moz_arena_calloc(arena_id_t aArenaId, size_t aNum, |
| 1950 | size_t aReqSize) { |
| 1951 | return PageCalloc(Some(aArenaId), aNum, aReqSize); |
| 1952 | } |
| 1953 | |
| 1954 | inline void* MozJemallocPHC::moz_arena_realloc(arena_id_t aArenaId, |
| 1955 | void* aOldPtr, size_t aNewSize) { |
| 1956 | return PageRealloc(Some(aArenaId), aOldPtr, aNewSize); |
| 1957 | } |
| 1958 | |
| 1959 | inline void MozJemallocPHC::moz_arena_free(arena_id_t aArenaId, void* aPtr) { |
| 1960 | return PageFree(Some(aArenaId), aPtr); |
| 1961 | } |
| 1962 | |
| 1963 | inline void* MozJemallocPHC::moz_arena_memalign(arena_id_t aArenaId, |
| 1964 | size_t aAlignment, |
| 1965 | size_t aReqSize) { |
| 1966 | return PageMemalign(Some(aArenaId), aAlignment, aReqSize); |
| 1967 | } |
| 1968 | |
| 1969 | namespace mozilla::phc { |
| 1970 | |
| 1971 | bool IsPHCAllocation(const void* aPtr, AddrInfo* aOut) { |
| 1972 | if (!maybe_init()) { |
| 1973 | return false; |
| 1974 | } |
| 1975 | |
| 1976 | PtrKind pk = PHC::sRegion->PtrKind(aPtr); |
| 1977 | if (pk.IsNothing()) { |
| 1978 | return false; |
| 1979 | } |
| 1980 | |
| 1981 | bool isGuardPage = false; |
| 1982 | if (pk.IsGuardPage()) { |
| 1983 | if ((uintptr_t(aPtr) % kPageSize) < (kPageSize / 2)) { |
| 1984 | // The address is in the lower half of a guard page, so it's probably an |
| 1985 | // overflow. But first check that it is not on the very first guard |
| 1986 | // page, in which case it cannot be an overflow, and we ignore it. |
| 1987 | if (PHC::sRegion->IsInFirstGuardPage(aPtr)) { |
| 1988 | return false; |
| 1989 | } |
| 1990 | |
| 1991 | // Get the allocation page preceding this guard page. |
| 1992 | pk = PHC::sRegion->PtrKind(static_cast<const uint8_t*>(aPtr) - kPageSize); |
| 1993 | |
| 1994 | } else { |
| 1995 | // The address is in the upper half of a guard page, so it's probably an |
| 1996 | // underflow. Get the allocation page following this guard page. |
| 1997 | pk = PHC::sRegion->PtrKind(static_cast<const uint8_t*>(aPtr) + kPageSize); |
| 1998 | } |
| 1999 | |
| 2000 | // Make a note of the fact that we hit a guard page. |
| 2001 | isGuardPage = true; |
| 2002 | } |
| 2003 | |
| 2004 | // At this point we know we have an allocation page. |
| 2005 | uintptr_t index = pk.AllocPageIndex(); |
| 2006 | |
| 2007 | if (aOut) { |
| 2008 | if (PHC::sPHC->mMutex.TryLock()) { |
| 2009 | PHC::sPHC->FillAddrInfo(index, aPtr, isGuardPage, *aOut); |
| 2010 | LOG("IsPHCAllocation: %zu, %p, %zu, %zu, %zu\n", size_t(aOut->mKind), |
| 2011 | aOut->mBaseAddr, aOut->mUsableSize, |
| 2012 | aOut->mAllocStack.isSome() ? aOut->mAllocStack->mLength : 0, |
| 2013 | aOut->mFreeStack.isSome() ? aOut->mFreeStack->mLength : 0); |
| 2014 | PHC::sPHC->mMutex.Unlock(); |
| 2015 | } else { |
| 2016 | LOG("IsPHCAllocation: PHC is locked\n"); |
| 2017 | aOut->mPhcWasLocked = true; |
| 2018 | } |
| 2019 | } |
| 2020 | return true; |
| 2021 | } |
| 2022 | |
| 2023 | void DisablePHCOnCurrentThread() { |
| 2024 | PHC::DisableOnCurrentThread(); |
| 2025 | LOG("DisablePHCOnCurrentThread: %zu\n", 0ul); |
| 2026 | } |
| 2027 | |
| 2028 | void ReenablePHCOnCurrentThread() { |
| 2029 | PHC::sPHC->EnableOnCurrentThread(); |
| 2030 | LOG("ReenablePHCOnCurrentThread: %zu\n", 0ul); |
| 2031 | } |
| 2032 | |
| 2033 | bool IsPHCEnabledOnCurrentThread() { |
| 2034 | bool enabled = !PHC::IsDisabledOnCurrentThread(); |
| 2035 | LOG("IsPHCEnabledOnCurrentThread: %zu\n", size_t(enabled)); |
| 2036 | return enabled; |
| 2037 | } |
| 2038 | |
| 2039 | void PHCMemoryUsage(MemoryUsage& aMemoryUsage) { |
| 2040 | if (!maybe_init()) { |
| 2041 | aMemoryUsage = MemoryUsage(); |
| 2042 | return; |
| 2043 | } |
| 2044 | |
| 2045 | aMemoryUsage.mMetadataBytes = metadata_size(); |
| 2046 | if (PHC::sPHC) { |
| 2047 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 2048 | aMemoryUsage.mFragmentationBytes = PHC::sPHC->FragmentationBytes(); |
| 2049 | } else { |
| 2050 | aMemoryUsage.mFragmentationBytes = 0; |
| 2051 | } |
| 2052 | } |
| 2053 | |
| 2054 | void GetPHCStats(PHCStats& aStats) { |
| 2055 | if (!maybe_init()) { |
| 2056 | aStats = PHCStats(); |
| 2057 | return; |
| 2058 | } |
| 2059 | |
| 2060 | MutexAutoLock lock(PHC::sPHC->mMutex); |
| 2061 | |
| 2062 | aStats = PHC::sPHC->GetPageStats(lock); |
| 2063 | } |
| 2064 | |
| 2065 | // Enable or Disable PHC at runtime. If PHC is disabled it will still trap |
| 2066 | // bad uses of previous allocations, but won't track any new allocations. |
| 2067 | void SetPHCState(PHCState aState) { |
| 2068 | if (!maybe_init()) { |
| 2069 | return; |
| 2070 | } |
| 2071 | |
| 2072 | PHC::sPHC->SetState(aState); |
| 2073 | } |
| 2074 | |
| 2075 | void SetPHCProbabilities(int64_t aAvgDelayFirst, int64_t aAvgDelayNormal, |
| 2076 | int64_t aAvgDelayPageReuse) { |
| 2077 | if (!maybe_init()) { |
| 2078 | return; |
| 2079 | } |
| 2080 | |
| 2081 | PHC::sPHC->SetProbabilities(aAvgDelayFirst, aAvgDelayNormal, |
| 2082 | aAvgDelayPageReuse); |
| 2083 | } |
| 2084 | |
| 2085 | } // namespace mozilla::phc |