File: | root/firefox-clang/memory/build/PHC.cpp |
Warning: | line 656, 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 | #include "FdPrintf.h" |
114 | #include "Mutex.h" |
115 | #include "mozilla/Array.h" |
116 | #include "mozilla/Assertions.h" |
117 | #include "mozilla/Atomics.h" |
118 | #include "mozilla/Attributes.h" |
119 | #include "mozilla/CheckedInt.h" |
120 | #include "mozilla/Maybe.h" |
121 | #include "mozilla/StackWalk.h" |
122 | #include "mozilla/ThreadLocal.h" |
123 | #include "mozilla/XorShift128PlusRNG.h" |
124 | |
125 | using namespace mozilla; |
126 | |
127 | //--------------------------------------------------------------------------- |
128 | // Utilities |
129 | //--------------------------------------------------------------------------- |
130 | |
131 | #ifdef ANDROID |
132 | // Android doesn't have pthread_atfork defined in pthread.h. |
133 | extern "C" MOZ_EXPORT__attribute__((visibility("default"))) int pthread_atfork(void (*)(void), void (*)(void), |
134 | void (*)(void)); |
135 | #endif |
136 | |
137 | #ifndef DISALLOW_COPY_AND_ASSIGN |
138 | # define DISALLOW_COPY_AND_ASSIGN(T)T(const T&); void operator=(const T&) \ |
139 | T(const T&); \ |
140 | void operator=(const T&) |
141 | #endif |
142 | |
143 | // This class provides infallible operations for the small number of heap |
144 | // allocations that PHC does for itself. It would be nice if we could use the |
145 | // InfallibleAllocPolicy from mozalloc, but PHC cannot use mozalloc. |
146 | class InfallibleAllocPolicy { |
147 | public: |
148 | static void AbortOnFailure(const void* aP) { |
149 | if (!aP) { |
150 | MOZ_CRASH("PHC failed to allocate")do { do { } while (false); MOZ_ReportCrash("" "PHC failed to allocate" , "/root/firefox-clang/memory/build/PHC.cpp", 150); AnnotateMozCrashReason ("MOZ_CRASH(" "PHC failed to allocate" ")"); do { MOZ_CrashSequence (__null, 150); __attribute__((nomerge)) ::abort(); } while (false ); } while (false); |
151 | } |
152 | } |
153 | |
154 | template <class T> |
155 | static T* new_() { |
156 | void* p = MozJemalloc::malloc(sizeof(T)); |
157 | AbortOnFailure(p); |
158 | return new (p) T; |
159 | } |
160 | }; |
161 | |
162 | //--------------------------------------------------------------------------- |
163 | // Stack traces |
164 | //--------------------------------------------------------------------------- |
165 | |
166 | // This code is similar to the equivalent code within DMD. |
167 | |
168 | class StackTrace : public phc::StackTrace { |
169 | public: |
170 | StackTrace() = default; |
171 | |
172 | void Clear() { mLength = 0; } |
173 | |
174 | void Fill(); |
175 | |
176 | private: |
177 | static void StackWalkCallback(uint32_t aFrameNumber, void* aPc, void* aSp, |
178 | void* aClosure) { |
179 | StackTrace* st = (StackTrace*)aClosure; |
180 | 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", "/root/firefox-clang/memory/build/PHC.cpp" , 180); AnnotateMozCrashReason("MOZ_ASSERT" "(" "st->mLength < kMaxFrames" ")"); do { MOZ_CrashSequence(__null, 180); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
181 | st->mPcs[st->mLength] = aPc; |
182 | st->mLength++; |
183 | 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", "/root/firefox-clang/memory/build/PHC.cpp" , 183); AnnotateMozCrashReason("MOZ_ASSERT" "(" "st->mLength == aFrameNumber" ")"); do { MOZ_CrashSequence(__null, 183); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
184 | } |
185 | }; |
186 | |
187 | // WARNING WARNING WARNING: this function must only be called when PHC::mMutex |
188 | // is *not* locked, otherwise we might get deadlocks. |
189 | // |
190 | // How? On Windows, MozStackWalk() can lock a mutex, M, from the shared library |
191 | // loader. Another thread might call malloc() while holding M locked (when |
192 | // loading a shared library) and try to lock PHC::mMutex, causing a deadlock. |
193 | // So PHC::mMutex can't be locked during the call to MozStackWalk(). (For |
194 | // details, see https://bugzilla.mozilla.org/show_bug.cgi?id=374829#c8. On |
195 | // Linux, something similar can happen; see bug 824340. So we just disallow it |
196 | // on all platforms.) |
197 | // |
198 | // In DMD, to avoid this problem we temporarily unlock the equivalent mutex for |
199 | // the MozStackWalk() call. But that's grotty, and things are a bit different |
200 | // here, so we just require that stack traces be obtained before locking |
201 | // PHC::mMutex. |
202 | // |
203 | // Unfortunately, there is no reliable way at compile-time or run-time to ensure |
204 | // this pre-condition. Hence this large comment. |
205 | // |
206 | void StackTrace::Fill() { |
207 | mLength = 0; |
208 | |
209 | // These ifdefs should be kept in sync with the conditions in |
210 | // phc_implies_frame_pointers in build/moz.configure/memory.configure |
211 | #if defined(XP_WIN) && defined(_M_IX86) |
212 | // This avoids MozStackWalk(), which causes unusably slow startup on Win32 |
213 | // when it is called during static initialization (see bug 1241684). |
214 | // |
215 | // This code is cribbed from the Gecko Profiler, which also uses |
216 | // FramePointerStackWalk() on Win32: Registers::SyncPopulate() for the |
217 | // frame pointer, and GetStackTop() for the stack end. |
218 | CONTEXT context; |
219 | RtlCaptureContext(&context); |
220 | void** fp = reinterpret_cast<void**>(context.Ebp); |
221 | |
222 | PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb()); |
223 | void* stackEnd = static_cast<void*>(pTib->StackBase); |
224 | FramePointerStackWalk(StackWalkCallback, kMaxFrames, this, fp, stackEnd); |
225 | #elif defined(XP_DARWIN) |
226 | // This avoids MozStackWalk(), which has become unusably slow on Mac due to |
227 | // changes in libunwind. |
228 | // |
229 | // This code is cribbed from the Gecko Profiler, which also uses |
230 | // FramePointerStackWalk() on Mac: Registers::SyncPopulate() for the frame |
231 | // pointer, and GetStackTop() for the stack end. |
232 | # pragma GCC diagnostic push |
233 | # pragma GCC diagnostic ignored "-Wframe-address" |
234 | void** fp = reinterpret_cast<void**>(__builtin_frame_address(1)); |
235 | # pragma GCC diagnostic pop |
236 | void* stackEnd = pthread_get_stackaddr_np(pthread_self()); |
237 | FramePointerStackWalk(StackWalkCallback, kMaxFrames, this, fp, stackEnd); |
238 | #else |
239 | MozStackWalk(StackWalkCallback, nullptr, kMaxFrames, this); |
240 | #endif |
241 | } |
242 | |
243 | //--------------------------------------------------------------------------- |
244 | // Logging |
245 | //--------------------------------------------------------------------------- |
246 | |
247 | // Change this to 1 to enable some PHC logging. Useful for debugging. |
248 | #define PHC_LOGGING0 0 |
249 | |
250 | static void Log(const char* fmt, ...); |
251 | |
252 | //--------------------------------------------------------------------------- |
253 | // Global state |
254 | //--------------------------------------------------------------------------- |
255 | |
256 | // Throughout this entire file time is measured as the number of sub-page |
257 | // allocations performed (by PHC and mozjemalloc combined). `Time` is 64-bit |
258 | // because we could have more than 2**32 allocations in a long-running session. |
259 | // `Delay` is 32-bit because the delays used within PHC are always much smaller |
260 | // than 2**32. Delay must be unsigned so that IsPowerOfTwo() can work on some |
261 | // Delay values. |
262 | using Time = uint64_t; // A moment in time. |
263 | using Delay = uint32_t; // A time duration. |
264 | static constexpr Delay DELAY_MAX = UINT32_MAX(4294967295U) / 2; |
265 | |
266 | // PHC only runs if the page size is 4 KiB; anything more is uncommon and would |
267 | // use too much memory. So we hardwire this size for all platforms but macOS |
268 | // on ARM processors. For the latter we make an exception because the minimum |
269 | // page size supported is 16KiB so there's no way to go below that. |
270 | static const size_t kPageSize = |
271 | #if defined(XP_DARWIN) && defined(__aarch64__) |
272 | 16384 |
273 | #else |
274 | 4096 |
275 | #endif |
276 | ; |
277 | |
278 | // We align the PHC area to a multiple of the jemalloc and JS GC chunk size |
279 | // (both use 1MB aligned chunks) so that their address computations don't lead |
280 | // from non-PHC memory into PHC memory causing misleading PHC stacks to be |
281 | // attached to a crash report. |
282 | static const size_t kPhcAlign = 1024 * 1024; |
283 | |
284 | static_assert(IsPowerOfTwo(kPhcAlign)); |
285 | static_assert((kPhcAlign % kPageSize) == 0); |
286 | |
287 | // There are two kinds of page. |
288 | // - Allocation pages, from which allocations are made. |
289 | // - Guard pages, which are never touched by PHC. |
290 | // |
291 | // These page kinds are interleaved; each allocation page has a guard page on |
292 | // either side. |
293 | #ifdef EARLY_BETA_OR_EARLIER1 |
294 | static const size_t kNumAllocPages = kPageSize == 4096 ? 4096 : 1024; |
295 | #else |
296 | // This will use between 82KiB and 1.1MiB per process (depending on how many |
297 | // objects are currently allocated). We will tune this in the future. |
298 | static const size_t kNumAllocPages = kPageSize == 4096 ? 256 : 64; |
299 | #endif |
300 | static const size_t kNumAllPages = kNumAllocPages * 2 + 1; |
301 | |
302 | // The total size of the allocation pages and guard pages. |
303 | static const size_t kAllPagesSize = kNumAllPages * kPageSize; |
304 | |
305 | // jemalloc adds a guard page to the end of our allocation, see the comment in |
306 | // AllocVirtualAddresses() for more information. |
307 | static const size_t kAllPagesJemallocSize = kAllPagesSize - kPageSize; |
308 | |
309 | // The amount to decrement from the shared allocation delay each time a thread's |
310 | // local allocation delay reaches zero. |
311 | static const Delay kDelayDecrementAmount = 256; |
312 | |
313 | // When PHC is disabled on the current thread wait this many allocations before |
314 | // accessing sAllocDelay once more. |
315 | static const Delay kDelayBackoffAmount = 64; |
316 | |
317 | // When PHC is disabled globally reset the shared delay by this many allocations |
318 | // to keep code running on the fast path. |
319 | static const Delay kDelayResetWhenDisabled = 64 * 1024; |
320 | |
321 | // The default state for PHC. Either Enabled or OnlyFree. |
322 | #define DEFAULT_STATEmozilla::phc::OnlyFree mozilla::phc::OnlyFree |
323 | |
324 | // The maximum time. |
325 | static const Time kMaxTime = ~(Time(0)); |
326 | |
327 | // Truncate aRnd to the range (1 .. aAvgDelay*2). If aRnd is random, this |
328 | // results in an average value of aAvgDelay + 0.5, which is close enough to |
329 | // aAvgDelay. aAvgDelay must be a power-of-two for speed. |
330 | constexpr Delay Rnd64ToDelay(Delay aAvgDelay, uint64_t aRnd) { |
331 | 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" ")", "/root/firefox-clang/memory/build/PHC.cpp" , 331); AnnotateMozCrashReason("MOZ_ASSERT" "(" "IsPowerOfTwo(aAvgDelay)" ") (" "must be a power of two" ")"); do { MOZ_CrashSequence( __null, 331); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
332 | |
333 | return (aRnd & (uint64_t(aAvgDelay) * 2 - 1)) + 1; |
334 | } |
335 | |
336 | static Delay CheckProbability(int64_t aProb) { |
337 | // Limit delays calculated from prefs to 0x80000000, this is the largest |
338 | // power-of-two that fits in a Delay since it is a uint32_t. |
339 | // The minimum is 2 that way not every allocation goes straight to PHC. |
340 | return RoundUpPow2(std::clamp(aProb, int64_t(2), int64_t(0x80000000))); |
341 | } |
342 | |
343 | // Maps a pointer to a PHC-specific structure: |
344 | // - Nothing |
345 | // - A guard page (it is unspecified which one) |
346 | // - An allocation page (with an index < kNumAllocPages) |
347 | // |
348 | // The standard way of handling a PtrKind is to check IsNothing(), and if that |
349 | // fails, to check IsGuardPage(), and if that fails, to call AllocPage(). |
350 | class PtrKind { |
351 | private: |
352 | enum class Tag : uint8_t { |
353 | Nothing, |
354 | GuardPage, |
355 | AllocPage, |
356 | }; |
357 | |
358 | Tag mTag; |
359 | uintptr_t mIndex; // Only used if mTag == Tag::AllocPage. |
360 | |
361 | public: |
362 | // Detect what a pointer points to. This constructor must be fast because it |
363 | // is called for every call to free(), realloc(), malloc_usable_size(), and |
364 | // jemalloc_ptr_info(). |
365 | PtrKind(const void* aPtr, const uint8_t* aPagesStart, |
366 | const uint8_t* aPagesLimit) { |
367 | if (!(aPagesStart <= aPtr && aPtr < aPagesLimit)) { |
368 | mTag = Tag::Nothing; |
369 | } else { |
370 | uintptr_t offset = static_cast<const uint8_t*>(aPtr) - aPagesStart; |
371 | uintptr_t allPageIndex = offset / kPageSize; |
372 | 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", "/root/firefox-clang/memory/build/PHC.cpp" , 372); AnnotateMozCrashReason("MOZ_ASSERT" "(" "allPageIndex < kNumAllPages" ")"); do { MOZ_CrashSequence(__null, 372); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
373 | if (allPageIndex & 1) { |
374 | // Odd-indexed pages are allocation pages. |
375 | uintptr_t allocPageIndex = allPageIndex / 2; |
376 | 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", "/root/firefox-clang/memory/build/PHC.cpp" , 376); AnnotateMozCrashReason("MOZ_ASSERT" "(" "allocPageIndex < kNumAllocPages" ")"); do { MOZ_CrashSequence(__null, 376); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
377 | mTag = Tag::AllocPage; |
378 | mIndex = allocPageIndex; |
379 | } else { |
380 | // Even-numbered pages are guard pages. |
381 | mTag = Tag::GuardPage; |
382 | } |
383 | } |
384 | } |
385 | |
386 | bool IsNothing() const { return mTag == Tag::Nothing; } |
387 | bool IsGuardPage() const { return mTag == Tag::GuardPage; } |
388 | |
389 | // This should only be called after IsNothing() and IsGuardPage() have been |
390 | // checked and failed. |
391 | uintptr_t AllocPageIndex() const { |
392 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 392); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "mTag == Tag::AllocPage" ")"); do { MOZ_CrashSequence(__null, 392); __attribute__((nomerge)) ::abort (); } while (false); } } while (false); |
393 | return mIndex; |
394 | } |
395 | }; |
396 | |
397 | // On MacOS, the first __thread/thread_local access calls malloc, which leads |
398 | // to an infinite loop. So we use pthread-based TLS instead, which somehow |
399 | // doesn't have this problem. |
400 | #if !defined(XP_DARWIN) |
401 | # 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> |
402 | #else |
403 | # define PHC_THREAD_LOCAL(T)__thread ::mozilla::detail::ThreadLocal< T, ::mozilla::detail ::ThreadLocalNativeStorage> \ |
404 | detail::ThreadLocal<T, detail::ThreadLocalKeyStorage> |
405 | #endif |
406 | |
407 | enum class AllocPageState { |
408 | NeverAllocated = 0, |
409 | InUse = 1, |
410 | Freed = 2, |
411 | }; |
412 | |
413 | // Metadata for each allocation page. |
414 | class AllocPageInfo { |
415 | public: |
416 | AllocPageInfo() |
417 | : mState(AllocPageState::NeverAllocated), |
418 | mBaseAddr(nullptr), |
419 | mReuseTime(0) {} |
420 | |
421 | // The current allocation page state. |
422 | AllocPageState mState; |
423 | |
424 | // The arena that the allocation is nominally from. This isn't meaningful |
425 | // within PHC, which has no arenas. But it is necessary for reallocation of |
426 | // page allocations as normal allocations, such as in this code: |
427 | // |
428 | // p = moz_arena_malloc(arenaId, 4096); |
429 | // realloc(p, 8192); |
430 | // |
431 | // The realloc is more than one page, and thus too large for PHC to handle. |
432 | // Therefore, if PHC handles the first allocation, it must ask mozjemalloc |
433 | // to allocate the 8192 bytes in the correct arena, and to do that, it must |
434 | // call MozJemalloc::moz_arena_malloc with the correct arenaId under the |
435 | // covers. Therefore it must record that arenaId. |
436 | // |
437 | // This field is also needed for jemalloc_ptr_info() to work, because it |
438 | // also returns the arena ID (but only in debug builds). |
439 | // |
440 | // - NeverAllocated: must be 0. |
441 | // - InUse | Freed: can be any valid arena ID value. |
442 | Maybe<arena_id_t> mArenaId; |
443 | |
444 | // The starting address of the allocation. Will not be the same as the page |
445 | // address unless the allocation is a full page. |
446 | // - NeverAllocated: must be 0. |
447 | // - InUse | Freed: must be within the allocation page. |
448 | uint8_t* mBaseAddr; |
449 | |
450 | // Usable size is computed as the number of bytes between the pointer and |
451 | // the end of the allocation page. This might be bigger than the requested |
452 | // size, especially if an outsized alignment is requested. |
453 | size_t UsableSize() const { |
454 | return mState == AllocPageState::NeverAllocated |
455 | ? 0 |
456 | : kPageSize - |
457 | (reinterpret_cast<uintptr_t>(mBaseAddr) & (kPageSize - 1)); |
458 | } |
459 | |
460 | // The internal fragmentation for this allocation. |
461 | size_t FragmentationBytes() const { |
462 | 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()", "/root/firefox-clang/memory/build/PHC.cpp" , 462); AnnotateMozCrashReason("MOZ_ASSERT" "(" "kPageSize >= UsableSize()" ")"); do { MOZ_CrashSequence(__null, 462); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
463 | return mState == AllocPageState::InUse ? kPageSize - UsableSize() : 0; |
464 | } |
465 | |
466 | // The allocation stack. |
467 | // - NeverAllocated: Nothing. |
468 | // - InUse | Freed: Some. |
469 | Maybe<StackTrace> mAllocStack; |
470 | |
471 | // The free stack. |
472 | // - NeverAllocated | InUse: Nothing. |
473 | // - Freed: Some. |
474 | Maybe<StackTrace> mFreeStack; |
475 | |
476 | // The time at which the page is available for reuse, as measured against |
477 | // mNow. When the page is in use this value will be kMaxTime. |
478 | // - NeverAllocated: must be 0. |
479 | // - InUse: must be kMaxTime. |
480 | // - Freed: must be > 0 and < kMaxTime. |
481 | Time mReuseTime; |
482 | |
483 | #if PHC_LOGGING0 |
484 | Time mFreeTime; |
485 | #endif |
486 | |
487 | // The next index for a free list of pages.` |
488 | Maybe<uintptr_t> mNextPage; |
489 | |
490 | void AssertInUse() const { |
491 | MOZ_ASSERT(mState == AllocPageState::InUse)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mState == AllocPageState::InUse)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mState == AllocPageState::InUse ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "mState == AllocPageState::InUse", "/root/firefox-clang/memory/build/PHC.cpp" , 491); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mState == AllocPageState::InUse" ")"); do { MOZ_CrashSequence(__null, 491); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
492 | // There is nothing to assert about aPage.mArenaId. |
493 | MOZ_ASSERT(mBaseAddr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mBaseAddr)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mBaseAddr))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("mBaseAddr", "/root/firefox-clang/memory/build/PHC.cpp" , 493); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mBaseAddr" ")" ); do { MOZ_CrashSequence(__null, 493); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
494 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 494); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "UsableSize() > 0" ")"); do { MOZ_CrashSequence (__null, 494); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
495 | MOZ_ASSERT(mAllocStack.isSome())do { static_assert( mozilla::detail::AssertionConditionType< decltype(mAllocStack.isSome())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mAllocStack.isSome()))), 0)) ) { do { } while (false); MOZ_ReportAssertionFailure("mAllocStack.isSome()" , "/root/firefox-clang/memory/build/PHC.cpp", 495); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mAllocStack.isSome()" ")"); do { MOZ_CrashSequence (__null, 495); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
496 | MOZ_ASSERT(mFreeStack.isNothing())do { static_assert( mozilla::detail::AssertionConditionType< decltype(mFreeStack.isNothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mFreeStack.isNothing()))), 0 ))) { do { } while (false); MOZ_ReportAssertionFailure("mFreeStack.isNothing()" , "/root/firefox-clang/memory/build/PHC.cpp", 496); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mFreeStack.isNothing()" ")"); do { MOZ_CrashSequence (__null, 496); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
497 | MOZ_ASSERT(mReuseTime == kMaxTime)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mReuseTime == kMaxTime)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mReuseTime == kMaxTime))), 0 ))) { do { } while (false); MOZ_ReportAssertionFailure("mReuseTime == kMaxTime" , "/root/firefox-clang/memory/build/PHC.cpp", 497); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mReuseTime == kMaxTime" ")"); do { MOZ_CrashSequence (__null, 497); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
498 | MOZ_ASSERT(!mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!mNextPage", "/root/firefox-clang/memory/build/PHC.cpp" , 498); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!mNextPage" ")" ); do { MOZ_CrashSequence(__null, 498); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
499 | } |
500 | |
501 | void AssertNotInUse() const { |
502 | // We can assert a lot about `NeverAllocated` pages, but not much about |
503 | // `Freed` pages. |
504 | #ifdef DEBUG1 |
505 | bool isFresh = mState == AllocPageState::NeverAllocated; |
506 | MOZ_ASSERT(isFresh || mState == AllocPageState::Freed)do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh || mState == AllocPageState::Freed)>::isValid , "invalid assertion condition"); if ((__builtin_expect(!!(!( !!(isFresh || mState == AllocPageState::Freed))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("isFresh || mState == AllocPageState::Freed" , "/root/firefox-clang/memory/build/PHC.cpp", 506); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "isFresh || mState == AllocPageState::Freed" ")"); do { MOZ_CrashSequence(__null, 506); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
507 | MOZ_ASSERT_IF(isFresh, mArenaId == Nothing())do { if (isFresh) { do { static_assert( mozilla::detail::AssertionConditionType <decltype(mArenaId == Nothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mArenaId == Nothing()))), 0) )) { do { } while (false); MOZ_ReportAssertionFailure("mArenaId == Nothing()" , "/root/firefox-clang/memory/build/PHC.cpp", 507); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mArenaId == Nothing()" ")"); do { MOZ_CrashSequence (__null, 507); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); } } while (false); |
508 | MOZ_ASSERT(isFresh == (mBaseAddr == nullptr))do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh == (mBaseAddr == nullptr))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(isFresh == (mBaseAddr == nullptr )))), 0))) { do { } while (false); MOZ_ReportAssertionFailure ("isFresh == (mBaseAddr == nullptr)", "/root/firefox-clang/memory/build/PHC.cpp" , 508); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh == (mBaseAddr == nullptr)" ")"); do { MOZ_CrashSequence(__null, 508); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
509 | MOZ_ASSERT(isFresh == (mAllocStack.isNothing()))do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh == (mAllocStack.isNothing()))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(isFresh == (mAllocStack.isNothing ())))), 0))) { do { } while (false); MOZ_ReportAssertionFailure ("isFresh == (mAllocStack.isNothing())", "/root/firefox-clang/memory/build/PHC.cpp" , 509); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh == (mAllocStack.isNothing())" ")"); do { MOZ_CrashSequence(__null, 509); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
510 | MOZ_ASSERT(isFresh == (mFreeStack.isNothing()))do { static_assert( mozilla::detail::AssertionConditionType< decltype(isFresh == (mFreeStack.isNothing()))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(isFresh == (mFreeStack.isNothing ())))), 0))) { do { } while (false); MOZ_ReportAssertionFailure ("isFresh == (mFreeStack.isNothing())", "/root/firefox-clang/memory/build/PHC.cpp" , 510); AnnotateMozCrashReason("MOZ_ASSERT" "(" "isFresh == (mFreeStack.isNothing())" ")"); do { MOZ_CrashSequence(__null, 510); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
511 | MOZ_ASSERT(mReuseTime != kMaxTime)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mReuseTime != kMaxTime)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mReuseTime != kMaxTime))), 0 ))) { do { } while (false); MOZ_ReportAssertionFailure("mReuseTime != kMaxTime" , "/root/firefox-clang/memory/build/PHC.cpp", 511); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mReuseTime != kMaxTime" ")"); do { MOZ_CrashSequence (__null, 511); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
512 | #endif |
513 | } |
514 | |
515 | bool IsPageInUse() const { return mState == AllocPageState::InUse; } |
516 | bool IsPageFreed() const { return mState == AllocPageState::Freed; } |
517 | |
518 | bool IsPageAllocatable(Time aNow) const { |
519 | return !IsPageInUse() && aNow >= mReuseTime; |
520 | } |
521 | |
522 | void SetInUse(const Maybe<arena_id_t>& aArenaId, uint8_t* aBaseAddr, |
523 | const StackTrace& aAllocStack) { |
524 | AssertNotInUse(); |
525 | mState = AllocPageState::InUse; |
526 | mArenaId = aArenaId; |
527 | mBaseAddr = aBaseAddr; |
528 | mAllocStack = Some(aAllocStack); |
529 | mFreeStack = Nothing(); |
530 | mReuseTime = kMaxTime; |
531 | |
532 | MOZ_ASSERT(!mNextPage)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!mNextPage)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!mNextPage))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!mNextPage", "/root/firefox-clang/memory/build/PHC.cpp" , 532); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!mNextPage" ")" ); do { MOZ_CrashSequence(__null, 532); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
533 | } |
534 | |
535 | void ResizeInUse(const Maybe<arena_id_t>& aArenaId, uint8_t* aNewBaseAddr, |
536 | const StackTrace& aAllocStack) { |
537 | AssertInUse(); |
538 | |
539 | // page.mState is not changed. |
540 | if (aArenaId.isSome()) { |
541 | // Crash if the arenas don't match. |
542 | MOZ_RELEASE_ASSERT(mArenaId == aArenaId)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mArenaId == aArenaId)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mArenaId == aArenaId))), 0)) ) { do { } while (false); MOZ_ReportAssertionFailure("mArenaId == aArenaId" , "/root/firefox-clang/memory/build/PHC.cpp", 542); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "mArenaId == aArenaId" ")"); do { MOZ_CrashSequence (__null, 542); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
543 | } |
544 | mBaseAddr = aNewBaseAddr; |
545 | // We could just keep the original alloc stack, but the realloc stack is |
546 | // more recent and therefore seems more useful. |
547 | mAllocStack = Some(aAllocStack); |
548 | // mFreeStack is not changed. |
549 | // mReuseTime is not changed. |
550 | // mNextPage is not changed. |
551 | } |
552 | |
553 | void SetPageFreed(const Maybe<arena_id_t>& aArenaId, |
554 | const StackTrace& aFreeStack, Delay aReuseDelay, |
555 | Time aNow) { |
556 | AssertInUse(); |
557 | |
558 | mState = AllocPageState::Freed; |
559 | |
560 | // page.mArenaId is left unchanged, for jemalloc_ptr_info() calls that |
561 | // occur after freeing (e.g. in the PtrInfo test in TestJemalloc.cpp). |
562 | if (aArenaId.isSome()) { |
563 | // Crash if the arenas don't match. |
564 | MOZ_RELEASE_ASSERT(mArenaId == aArenaId)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mArenaId == aArenaId)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(mArenaId == aArenaId))), 0)) ) { do { } while (false); MOZ_ReportAssertionFailure("mArenaId == aArenaId" , "/root/firefox-clang/memory/build/PHC.cpp", 564); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "mArenaId == aArenaId" ")"); do { MOZ_CrashSequence (__null, 564); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
565 | } |
566 | |
567 | // page.musableSize is left unchanged, for reporting on UAF, and for |
568 | // jemalloc_ptr_info() calls that occur after freeing (e.g. in the PtrInfo |
569 | // test in TestJemalloc.cpp). |
570 | |
571 | // page.mAllocStack is left unchanged, for reporting on UAF. |
572 | |
573 | mFreeStack = Some(aFreeStack); |
574 | #if PHC_LOGGING0 |
575 | mFreeTime = aNow; |
576 | #endif |
577 | mReuseTime = aNow + aReuseDelay; |
578 | } |
579 | }; |
580 | |
581 | // The virtual address space reserved by PHC. It is shared, immutable global |
582 | // state. Initialized by phc_init() and never changed after that. phc_init() |
583 | // runs early enough that no synchronization is needed. |
584 | class PHCRegion { |
585 | private: |
586 | // The bounds of PHC's virtual address space. These are only ever set once |
587 | // before any threads are spawned, after that they're read only, and therefore |
588 | // can be accessed without a lock. |
589 | uint8_t* mPagesStart = nullptr; |
590 | uint8_t* mPagesLimit = nullptr; |
591 | |
592 | public: |
593 | // Allocates the allocation pages and the guard pages, contiguously. |
594 | bool AllocVirtualAddresses() { |
595 | MOZ_ASSERT(!mPagesStart || !mPagesLimit)do { static_assert( mozilla::detail::AssertionConditionType< decltype(!mPagesStart || !mPagesLimit)>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!mPagesStart || !mPagesLimit ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "!mPagesStart || !mPagesLimit", "/root/firefox-clang/memory/build/PHC.cpp" , 595); AnnotateMozCrashReason("MOZ_ASSERT" "(" "!mPagesStart || !mPagesLimit" ")"); do { MOZ_CrashSequence(__null, 595); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
596 | |
597 | // The memory allocated here is never freed, because it would happen at |
598 | // process termination when it would be of little use. |
599 | |
600 | // We can rely on jemalloc's behaviour that when it allocates memory aligned |
601 | // with its own chunk size it will over-allocate and guarantee that the |
602 | // memory after the end of our allocation, but before the next chunk, is |
603 | // decommitted and inaccessible. Elsewhere in PHC we assume that we own |
604 | // that page (so that memory errors in it get caught by PHC) but here we |
605 | // use kAllPagesJemallocSize which subtracts jemalloc's guard page. |
606 | void* pages = MozJemalloc::memalign(kPhcAlign, kAllPagesJemallocSize); |
607 | if (!pages) { |
608 | return false; |
609 | } |
610 | |
611 | // Make the pages inaccessible. |
612 | #ifdef XP_WIN |
613 | if (!VirtualFree(pages, kAllPagesJemallocSize, MEM_DECOMMIT)) { |
614 | return false; |
615 | } |
616 | #else |
617 | if (mmap_mmap(pages, kAllPagesJemallocSize, PROT_NONE0x0, |
618 | MAP_FIXED0x10 | MAP_PRIVATE0x02 | MAP_ANON0x20, -1, 0) == MAP_FAILED((void *) -1)) { |
619 | return false; |
620 | } |
621 | #endif |
622 | |
623 | mPagesStart = static_cast<uint8_t*>(pages); |
624 | mPagesLimit = mPagesStart + kAllPagesSize; |
625 | Log("AllocVirtualAddresses at %p..%p\n", mPagesStart, mPagesLimit); |
626 | return true; |
627 | } |
628 | |
629 | constexpr PHCRegion() {} |
630 | |
631 | class PtrKind PtrKind(const void* aPtr) { |
632 | MOZ_ASSERT(mPagesStart != nullptr && mPagesLimit != nullptr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mPagesStart != nullptr && mPagesLimit != nullptr )>::isValid, "invalid assertion condition"); if ((__builtin_expect (!!(!(!!(mPagesStart != nullptr && mPagesLimit != nullptr ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "mPagesStart != nullptr && mPagesLimit != nullptr", "/root/firefox-clang/memory/build/PHC.cpp" , 632); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mPagesStart != nullptr && mPagesLimit != nullptr" ")"); do { MOZ_CrashSequence(__null, 632); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
633 | class PtrKind pk(aPtr, mPagesStart, mPagesLimit); |
634 | return pk; |
635 | } |
636 | |
637 | bool IsInFirstGuardPage(const void* aPtr) { |
638 | MOZ_ASSERT(mPagesStart != nullptr && mPagesLimit != nullptr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mPagesStart != nullptr && mPagesLimit != nullptr )>::isValid, "invalid assertion condition"); if ((__builtin_expect (!!(!(!!(mPagesStart != nullptr && mPagesLimit != nullptr ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "mPagesStart != nullptr && mPagesLimit != nullptr", "/root/firefox-clang/memory/build/PHC.cpp" , 638); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mPagesStart != nullptr && mPagesLimit != nullptr" ")"); do { MOZ_CrashSequence(__null, 638); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
639 | return mPagesStart <= aPtr && aPtr < mPagesStart + kPageSize; |
640 | } |
641 | |
642 | // Get the address of the allocation page referred to via an index. Used when |
643 | // marking the page as accessible/inaccessible. |
644 | uint8_t* AllocPagePtr(uintptr_t aIndex) { |
645 | MOZ_ASSERT(mPagesStart != nullptr && mPagesLimit != nullptr)do { static_assert( mozilla::detail::AssertionConditionType< decltype(mPagesStart != nullptr && mPagesLimit != nullptr )>::isValid, "invalid assertion condition"); if ((__builtin_expect (!!(!(!!(mPagesStart != nullptr && mPagesLimit != nullptr ))), 0))) { do { } while (false); MOZ_ReportAssertionFailure( "mPagesStart != nullptr && mPagesLimit != nullptr", "/root/firefox-clang/memory/build/PHC.cpp" , 645); AnnotateMozCrashReason("MOZ_ASSERT" "(" "mPagesStart != nullptr && mPagesLimit != nullptr" ")"); do { MOZ_CrashSequence(__null, 645); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
646 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 646); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "aIndex < kNumAllocPages" ")"); do { MOZ_CrashSequence (__null, 646); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
647 | // Multiply by two and add one to account for allocation pages *and* guard |
648 | // pages. |
649 | return mPagesStart + (2 * aIndex + 1) * kPageSize; |
650 | } |
651 | }; |
652 | |
653 | // Shared, mutable global state. Many fields are protected by sMutex; functions |
654 | // that access those feilds should take a PHCLock as proof that mMutex is held. |
655 | // Other fields are TLS or Atomic and don't need the lock. |
656 | 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 | |
657 | public: |
658 | // The RNG seeds here are poor, but non-reentrant since this can be called |
659 | // from malloc(). SetState() will reset the RNG later. |
660 | PHC() : mRNG(RandomSeed<1>(), RandomSeed<2>()) { |
661 | mMutex.Init(); |
662 | if (!tlsIsDisabled.init()) { |
663 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/root/firefox-clang/memory/build/PHC.cpp" , 663); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { MOZ_CrashSequence (__null, 663); __attribute__((nomerge)) ::abort(); } while (false ); } while (false); |
664 | } |
665 | if (!tlsAllocDelay.init()) { |
666 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/root/firefox-clang/memory/build/PHC.cpp" , 666); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { MOZ_CrashSequence (__null, 666); __attribute__((nomerge)) ::abort(); } while (false ); } while (false); |
667 | } |
668 | if (!tlsLastDelay.init()) { |
669 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/root/firefox-clang/memory/build/PHC.cpp" , 669); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { MOZ_CrashSequence (__null, 669); __attribute__((nomerge)) ::abort(); } while (false ); } while (false); |
670 | } |
671 | |
672 | // This constructor is part of PHC's very early initialisation, |
673 | // see phc_init(), and if PHC is default-on it'll start marking allocations |
674 | // and we must setup the delay. However once XPCOM starts it'll call |
675 | // SetState() which will re-initialise the RNG and allocation delay. |
676 | MutexAutoLock lock(mMutex); |
677 | |
678 | ForceSetNewAllocDelay(Rnd64ToDelay(mAvgFirstAllocDelay, Random64())); |
679 | |
680 | for (uintptr_t i = 0; i < kNumAllocPages; i++) { |
681 | AppendPageToFreeList(i); |
682 | } |
683 | } |
684 | |
685 | uint64_t Random64() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { return mRNG.next(); } |
686 | |
687 | // Get the address of the allocation page referred to via an index. Used |
688 | // when checking pointers against page boundaries. |
689 | uint8_t* AllocPageBaseAddr(uintptr_t aIndex) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
690 | return mAllocPages[aIndex].mBaseAddr; |
691 | } |
692 | |
693 | Maybe<arena_id_t> PageArena(uintptr_t aIndex) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
694 | const AllocPageInfo& page = mAllocPages[aIndex]; |
695 | page.AssertInUse(); |
696 | |
697 | return page.mArenaId; |
698 | } |
699 | |
700 | size_t PageUsableSize(uintptr_t aIndex) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
701 | const AllocPageInfo& page = mAllocPages[aIndex]; |
702 | page.AssertInUse(); |
703 | |
704 | return page.UsableSize(); |
705 | } |
706 | |
707 | // The total fragmentation in PHC |
708 | size_t FragmentationBytes() MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
709 | MutexAutoLock lock(mMutex); |
710 | |
711 | size_t sum = 0; |
712 | for (const auto& page : mAllocPages) { |
713 | sum += page.FragmentationBytes(); |
714 | } |
715 | return sum; |
716 | } |
717 | |
718 | // Used by the memory reporter to count usable space of in-use allocations. |
719 | size_t AllocatedBytes() MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
720 | MutexAutoLock lock(mMutex); |
721 | |
722 | size_t allocated = 0; |
723 | for (const auto& page : mAllocPages) { |
724 | if (page.IsPageInUse()) { |
725 | allocated += page.UsableSize(); |
726 | } |
727 | } |
728 | return allocated; |
729 | } |
730 | |
731 | void SetPageInUse(uintptr_t aIndex, const Maybe<arena_id_t>& aArenaId, |
732 | uint8_t* aBaseAddr, const StackTrace& aAllocStack) |
733 | MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
734 | mAllocPages[aIndex].SetInUse(aArenaId, aBaseAddr, aAllocStack); |
735 | } |
736 | |
737 | #if PHC_LOGGING0 |
738 | Time GetFreeTime(uintptr_t aIndex) const MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
739 | return mAllocPages[aIndex].mFreeTime; |
740 | } |
741 | #endif |
742 | |
743 | void ResizePageInUse(uintptr_t aIndex, const Maybe<arena_id_t>& aArenaId, |
744 | uint8_t* aNewBaseAddr, const StackTrace& aAllocStack) |
745 | MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
746 | mAllocPages[aIndex].ResizeInUse(aArenaId, aNewBaseAddr, aAllocStack); |
747 | }; |
748 | |
749 | void SetPageFreed(uintptr_t aIndex, const Maybe<arena_id_t>& aArenaId, |
750 | const StackTrace& aFreeStack, Delay aReuseDelay) |
751 | MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
752 | AllocPageInfo& page = mAllocPages[aIndex]; |
753 | |
754 | page.SetPageFreed(aArenaId, aFreeStack, aReuseDelay, Now()); |
755 | |
756 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 756); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { MOZ_CrashSequence (__null, 756); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
757 | AppendPageToFreeList(aIndex); |
758 | } |
759 | |
760 | static void CrashOnGuardPage(void* aPtr) { |
761 | // An operation on a guard page? This is a bounds violation. Deliberately |
762 | // touch the page in question to cause a crash that triggers the usual PHC |
763 | // machinery. |
764 | Log("CrashOnGuardPage(%p), bounds violation\n", aPtr); |
765 | *static_cast<uint8_t*>(aPtr) = 0; |
766 | MOZ_CRASH("unreachable")do { do { } while (false); MOZ_ReportCrash("" "unreachable", "/root/firefox-clang/memory/build/PHC.cpp" , 766); AnnotateMozCrashReason("MOZ_CRASH(" "unreachable" ")" ); do { MOZ_CrashSequence(__null, 766); __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
767 | } |
768 | |
769 | void EnsureValidAndInUse(void* aPtr, uintptr_t aIndex) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
770 | const AllocPageInfo& page = mAllocPages[aIndex]; |
771 | |
772 | // The pointer must point to the start of the allocation. |
773 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 773); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "page.mBaseAddr == aPtr" ")"); do { MOZ_CrashSequence(__null, 773); __attribute__((nomerge)) ::abort (); } while (false); } } while (false); |
774 | |
775 | if (page.mState == AllocPageState::Freed) { |
776 | Log("EnsureValidAndInUse(%p), use-after-free\n", aPtr); |
777 | // An operation on a freed page? This is a particular kind of |
778 | // use-after-free. Deliberately touch the page in question, in order to |
779 | // cause a crash that triggers the usual PHC machinery. But unlock mMutex |
780 | // first, because that self-same PHC machinery needs to re-lock it, and |
781 | // the crash causes non-local control flow so mMutex won't be unlocked |
782 | // the normal way in the caller. |
783 | mMutex.Unlock(); |
784 | *static_cast<uint8_t*>(aPtr) = 0; |
785 | MOZ_CRASH("unreachable")do { do { } while (false); MOZ_ReportCrash("" "unreachable", "/root/firefox-clang/memory/build/PHC.cpp" , 785); AnnotateMozCrashReason("MOZ_CRASH(" "unreachable" ")" ); do { MOZ_CrashSequence(__null, 785); __attribute__((nomerge )) ::abort(); } while (false); } while (false); |
786 | } |
787 | } |
788 | |
789 | // This expects sPHC::mMutex to be locked but can't check it with a parameter |
790 | // since we try-lock it. |
791 | void FillAddrInfo(uintptr_t aIndex, const void* aBaseAddr, bool isGuardPage, |
792 | phc::AddrInfo& aOut) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
793 | const AllocPageInfo& page = mAllocPages[aIndex]; |
794 | if (isGuardPage) { |
795 | aOut.mKind = phc::AddrInfo::Kind::GuardPage; |
796 | } else { |
797 | switch (page.mState) { |
798 | case AllocPageState::NeverAllocated: |
799 | aOut.mKind = phc::AddrInfo::Kind::NeverAllocatedPage; |
800 | break; |
801 | |
802 | case AllocPageState::InUse: |
803 | aOut.mKind = phc::AddrInfo::Kind::InUsePage; |
804 | break; |
805 | |
806 | case AllocPageState::Freed: |
807 | aOut.mKind = phc::AddrInfo::Kind::FreedPage; |
808 | break; |
809 | |
810 | default: |
811 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/root/firefox-clang/memory/build/PHC.cpp" , 811); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { MOZ_CrashSequence (__null, 811); __attribute__((nomerge)) ::abort(); } while (false ); } while (false); |
812 | } |
813 | } |
814 | aOut.mBaseAddr = page.mBaseAddr; |
815 | aOut.mUsableSize = page.UsableSize(); |
816 | aOut.mAllocStack = page.mAllocStack; |
817 | aOut.mFreeStack = page.mFreeStack; |
818 | } |
819 | |
820 | void FillJemallocPtrInfo(const void* aPtr, uintptr_t aIndex, |
821 | jemalloc_ptr_info_t* aInfo) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
822 | const AllocPageInfo& page = mAllocPages[aIndex]; |
823 | switch (page.mState) { |
824 | case AllocPageState::NeverAllocated: |
825 | break; |
826 | |
827 | case AllocPageState::InUse: { |
828 | // Only return TagLiveAlloc if the pointer is within the bounds of the |
829 | // allocation's usable size. |
830 | uint8_t* base = page.mBaseAddr; |
831 | uint8_t* limit = base + page.UsableSize(); |
832 | if (base <= aPtr && aPtr < limit) { |
833 | *aInfo = {TagLiveAlloc, page.mBaseAddr, page.UsableSize(), |
834 | page.mArenaId.valueOr(0)}; |
835 | return; |
836 | } |
837 | break; |
838 | } |
839 | |
840 | case AllocPageState::Freed: { |
841 | // Only return TagFreedAlloc if the pointer is within the bounds of the |
842 | // former allocation's usable size. |
843 | uint8_t* base = page.mBaseAddr; |
844 | uint8_t* limit = base + page.UsableSize(); |
845 | if (base <= aPtr && aPtr < limit) { |
846 | *aInfo = {TagFreedAlloc, page.mBaseAddr, page.UsableSize(), |
847 | page.mArenaId.valueOr(0)}; |
848 | return; |
849 | } |
850 | break; |
851 | } |
852 | |
853 | default: |
854 | MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/root/firefox-clang/memory/build/PHC.cpp" , 854); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { MOZ_CrashSequence (__null, 854); __attribute__((nomerge)) ::abort(); } while (false ); } while (false); |
855 | } |
856 | |
857 | // Pointers into guard pages will end up here, as will pointers into |
858 | // allocation pages that aren't within the allocation's bounds. |
859 | *aInfo = {TagUnknown, nullptr, 0, 0}; |
860 | } |
861 | |
862 | #ifndef XP_WIN |
863 | static void prefork() MOZ_NO_THREAD_SAFETY_ANALYSIS__attribute__((no_thread_safety_analysis)) { |
864 | PHC::sPHC->mMutex.Lock(); |
865 | } |
866 | static void postfork_parent() MOZ_NO_THREAD_SAFETY_ANALYSIS__attribute__((no_thread_safety_analysis)) { |
867 | PHC::sPHC->mMutex.Unlock(); |
868 | } |
869 | static void postfork_child() { PHC::sPHC->mMutex.Init(); } |
870 | #endif |
871 | |
872 | void IncPageAllocHits() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
873 | #if PHC_LOGGING0 |
874 | mPageAllocHits++; |
875 | #endif |
876 | } |
877 | void IncPageAllocMisses() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
878 | #if PHC_LOGGING0 |
879 | mPageAllocMisses++; |
880 | #endif |
881 | } |
882 | |
883 | phc::PHCStats GetPageStatsLocked() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
884 | phc::PHCStats stats; |
885 | |
886 | for (const auto& page : mAllocPages) { |
887 | stats.mSlotsAllocated += page.IsPageInUse() ? 1 : 0; |
888 | stats.mSlotsFreed += page.IsPageFreed() ? 1 : 0; |
889 | } |
890 | stats.mSlotsUnused = |
891 | kNumAllocPages - stats.mSlotsAllocated - stats.mSlotsFreed; |
892 | |
893 | return stats; |
894 | } |
895 | |
896 | phc::PHCStats GetPageStats() MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
897 | MutexAutoLock lock(mMutex); |
898 | return GetPageStatsLocked(); |
899 | } |
900 | |
901 | #if PHC_LOGGING0 |
902 | size_t PageAllocHits() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { return mPageAllocHits; } |
903 | size_t PageAllocAttempts() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
904 | return mPageAllocHits + mPageAllocMisses; |
905 | } |
906 | |
907 | // This is an integer because FdPrintf only supports integer printing. |
908 | size_t PageAllocHitRate() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
909 | return mPageAllocHits * 100 / (mPageAllocHits + mPageAllocMisses); |
910 | } |
911 | #endif |
912 | |
913 | void LogNoAlloc(size_t aReqSize, size_t aAlignment, Delay newAllocDelay); |
914 | |
915 | // Should we make new PHC allocations? |
916 | bool ShouldMakeNewAllocations() const { |
917 | return mPhcState == mozilla::phc::Enabled; |
918 | } |
919 | |
920 | using PHCState = mozilla::phc::PHCState; |
921 | void SetState(PHCState aState) { |
922 | if (mPhcState != PHCState::Enabled && aState == PHCState::Enabled) { |
923 | MutexAutoLock lock(mMutex); |
924 | // Reset the RNG at this point with a better seed. |
925 | ResetRNG(); |
926 | ForceSetNewAllocDelay(Rnd64ToDelay(mAvgFirstAllocDelay, Random64())); |
927 | } |
928 | |
929 | mPhcState = aState; |
930 | } |
931 | |
932 | void ResetRNG() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
933 | mRNG = non_crypto::XorShift128PlusRNG(RandomSeed<0>(), RandomSeed<1>()); |
934 | } |
935 | |
936 | void SetProbabilities(int64_t aAvgDelayFirst, int64_t aAvgDelayNormal, |
937 | int64_t aAvgDelayPageReuse) MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
938 | MutexAutoLock lock(mMutex); |
939 | |
940 | mAvgFirstAllocDelay = CheckProbability(aAvgDelayFirst); |
941 | mAvgAllocDelay = CheckProbability(aAvgDelayNormal); |
942 | mAvgPageReuseDelay = CheckProbability(aAvgDelayPageReuse); |
943 | } |
944 | |
945 | static void DisableOnCurrentThread() { |
946 | 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()" , "/root/firefox-clang/memory/build/PHC.cpp", 946); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!tlsIsDisabled.get()" ")"); do { MOZ_CrashSequence (__null, 946); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
947 | tlsIsDisabled.set(true); |
948 | } |
949 | |
950 | void EnableOnCurrentThread() { |
951 | 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()" , "/root/firefox-clang/memory/build/PHC.cpp", 951); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "tlsIsDisabled.get()" ")"); do { MOZ_CrashSequence (__null, 951); __attribute__((nomerge)) ::abort(); } while (false ); } } while (false); |
952 | tlsIsDisabled.set(false); |
953 | } |
954 | |
955 | static bool IsDisabledOnCurrentThread() { return tlsIsDisabled.get(); } |
956 | |
957 | static Time Now() { |
958 | if (!sPHC) { |
959 | return 0; |
960 | } |
961 | |
962 | return sPHC->mNow; |
963 | } |
964 | |
965 | void AdvanceNow(uint32_t delay = 0) { |
966 | mNow += tlsLastDelay.get() - delay; |
967 | tlsLastDelay.set(delay); |
968 | } |
969 | |
970 | // Decrements the delay and returns true if it's time to make a new PHC |
971 | // allocation. |
972 | static bool DecrementDelay() { |
973 | const Delay alloc_delay = tlsAllocDelay.get(); |
974 | |
975 | if (MOZ_LIKELY(alloc_delay > 0)(__builtin_expect(!!(alloc_delay > 0), 1))) { |
976 | tlsAllocDelay.set(alloc_delay - 1); |
977 | return false; |
978 | } |
979 | // The local delay has expired, check the shared delay. This path is also |
980 | // executed on a new thread's first allocation, the result is the same: all |
981 | // the thread's TLS fields will be initialised. |
982 | |
983 | // This accesses sPHC but we want to ensure it's still a static member |
984 | // function so that sPHC isn't dereferenced until after the hot path above. |
985 | 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", "/root/firefox-clang/memory/build/PHC.cpp" , 985); AnnotateMozCrashReason("MOZ_ASSERT" "(" "sPHC" ")"); do { MOZ_CrashSequence(__null, 985); __attribute__((nomerge)) :: abort(); } while (false); } } while (false); |
986 | sPHC->AdvanceNow(); |
987 | |
988 | // Use an atomic fetch-and-subtract. This uses unsigned underflow semantics |
989 | // to avoid doing a full compare-and-swap. |
990 | Delay new_delay = (sAllocDelay -= kDelayDecrementAmount); |
991 | Delay old_delay = new_delay + kDelayDecrementAmount; |
992 | if (MOZ_LIKELY(new_delay < DELAY_MAX)(__builtin_expect(!!(new_delay < DELAY_MAX), 1))) { |
993 | // Normal case, we decremented the shared delay but it's not yet |
994 | // underflowed. |
995 | tlsAllocDelay.set(kDelayDecrementAmount); |
996 | tlsLastDelay.set(kDelayDecrementAmount); |
997 | Log("Update sAllocDelay <- %zu, tlsAllocDelay <- %zu\n", |
998 | size_t(new_delay), size_t(kDelayDecrementAmount)); |
999 | return false; |
1000 | } |
1001 | |
1002 | if (old_delay < new_delay) { |
1003 | // The shared delay only just underflowed, so unless we hit exactly zero |
1004 | // we should set our local counter and continue. |
1005 | Log("Update sAllocDelay <- %zu, tlsAllocDelay <- %zu\n", |
1006 | size_t(new_delay), size_t(old_delay)); |
1007 | if (old_delay == 0) { |
1008 | // We don't need to set tlsAllocDelay because it's already zero, we know |
1009 | // because the condition at the beginning of this function failed. |
1010 | return true; |
1011 | } |
1012 | tlsAllocDelay.set(old_delay); |
1013 | tlsLastDelay.set(old_delay); |
1014 | return false; |
1015 | } |
1016 | |
1017 | // The delay underflowed on another thread or a previous failed allocation |
1018 | // by this thread. Return true and attempt the next allocation, if the |
1019 | // other thread wins we'll check for that before committing. |
1020 | Log("Update sAllocDelay <- %zu, tlsAllocDelay <- %zu\n", size_t(new_delay), |
1021 | size_t(alloc_delay)); |
1022 | return true; |
1023 | } |
1024 | |
1025 | static void ResetLocalAllocDelay(Delay aDelay = 0) { |
1026 | // We could take some delay from the shared delay but we'd need a |
1027 | // compare-and-swap because this is called on paths that don't make |
1028 | // allocations. Or we can set the local delay to zero and let it get |
1029 | // initialised on the next allocation. |
1030 | tlsAllocDelay.set(aDelay); |
1031 | tlsLastDelay.set(aDelay); |
1032 | } |
1033 | |
1034 | static void ForceSetNewAllocDelay(Delay aNewAllocDelay) { |
1035 | Log("Setting sAllocDelay <- %zu\n", size_t(aNewAllocDelay)); |
1036 | sAllocDelay = aNewAllocDelay; |
1037 | ResetLocalAllocDelay(); |
1038 | } |
1039 | |
1040 | // Set a new allocation delay and return true if the delay was less than zero |
1041 | // (but it's unsigned so interpret it as signed) indicating that we won the |
1042 | // race to make the next allocation. |
1043 | static bool SetNewAllocDelay(Delay aNewAllocDelay) { |
1044 | bool cas_retry; |
1045 | do { |
1046 | // We read the current delay on every iteration, we consider that the PHC |
1047 | // allocation is still "up for grabs" if sAllocDelay < 0. This is safe |
1048 | // even while other threads continuing to fetch-and-subtract sAllocDelay |
1049 | // in DecrementDelay(), up to DELAY_MAX (2^31) calls to DecrementDelay(). |
1050 | Delay read_delay = sAllocDelay; |
1051 | if (read_delay < DELAY_MAX) { |
1052 | // Another thread already set a valid delay. |
1053 | Log("Observe delay %zu this thread lost the race\n", |
1054 | size_t(read_delay)); |
1055 | ResetLocalAllocDelay(); |
1056 | return false; |
1057 | } else { |
1058 | Log("Preparing for CAS, read sAllocDelay %zu\n", size_t(read_delay)); |
1059 | } |
1060 | |
1061 | cas_retry = !sAllocDelay.compareExchange(read_delay, aNewAllocDelay); |
1062 | if (cas_retry) { |
1063 | Log("Lost the CAS, sAllocDelay is now %zu\n", size_t(sAllocDelay)); |
1064 | cpu_pause(); |
1065 | // We raced against another thread and lost. |
1066 | } |
1067 | } while (cas_retry); |
1068 | Log("Won the CAS, set sAllocDelay = %zu\n", size_t(sAllocDelay)); |
1069 | ResetLocalAllocDelay(); |
1070 | return true; |
1071 | } |
1072 | |
1073 | static Delay LocalAllocDelay() { return tlsAllocDelay.get(); } |
1074 | static Delay SharedAllocDelay() { return sAllocDelay; } |
1075 | |
1076 | static Delay LastDelay() { return tlsLastDelay.get(); } |
1077 | |
1078 | Maybe<uintptr_t> PopNextFreeIfAllocatable(Time now) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1079 | if (!mFreePageListHead) { |
1080 | return Nothing(); |
1081 | } |
1082 | |
1083 | uintptr_t index = mFreePageListHead.value(); |
1084 | |
1085 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1085); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "index < kNumAllocPages" ")"); do { MOZ_CrashSequence(__null, 1085); __attribute__((nomerge)) :: abort(); } while (false); } } while (false); |
1086 | AllocPageInfo& page = mAllocPages[index]; |
1087 | page.AssertNotInUse(); |
1088 | |
1089 | if (!page.IsPageAllocatable(now)) { |
1090 | return Nothing(); |
1091 | } |
1092 | |
1093 | mFreePageListHead = page.mNextPage; |
1094 | page.mNextPage = Nothing(); |
1095 | if (!mFreePageListHead) { |
1096 | mFreePageListTail = Nothing(); |
1097 | } |
1098 | |
1099 | return Some(index); |
1100 | } |
1101 | |
1102 | void UnpopNextFree(uintptr_t index) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1103 | AllocPageInfo& page = mAllocPages[index]; |
1104 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1104); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { MOZ_CrashSequence (__null, 1104); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1105 | |
1106 | page.mNextPage = mFreePageListHead; |
1107 | mFreePageListHead = Some(index); |
1108 | if (!mFreePageListTail) { |
1109 | mFreePageListTail = Some(index); |
1110 | } |
1111 | } |
1112 | |
1113 | void AppendPageToFreeList(uintptr_t aIndex) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1114 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1114); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "aIndex < kNumAllocPages" ")"); do { MOZ_CrashSequence(__null, 1114); __attribute__((nomerge)) :: abort(); } while (false); } } while (false); |
1115 | AllocPageInfo& page = mAllocPages[aIndex]; |
1116 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1116); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!page.mNextPage" ")"); do { MOZ_CrashSequence (__null, 1116); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1117 | 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)" , "/root/firefox-clang/memory/build/PHC.cpp", 1118); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex)" ")"); do { MOZ_CrashSequence(__null, 1118); __attribute__((nomerge )) ::abort(); } while (false); } } while (false) |
1118 | 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)" , "/root/firefox-clang/memory/build/PHC.cpp", 1118); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mFreePageListHead != Some(aIndex) && mFreePageListTail != Some(aIndex)" ")"); do { MOZ_CrashSequence(__null, 1118); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
1119 | |
1120 | if (!mFreePageListTail) { |
1121 | // The list is empty this page will become the beginning and end. |
1122 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1122); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!mFreePageListHead" ")"); do { MOZ_CrashSequence (__null, 1122); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1123 | mFreePageListHead = Some(aIndex); |
1124 | } else { |
1125 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1125); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "mFreePageListTail.value() < kNumAllocPages" ")"); do { MOZ_CrashSequence(__null, 1125); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
1126 | AllocPageInfo& tail_page = mAllocPages[mFreePageListTail.value()]; |
1127 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1127); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!tail_page.mNextPage" ")"); do { MOZ_CrashSequence (__null, 1127); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1128 | tail_page.mNextPage = Some(aIndex); |
1129 | } |
1130 | page.mNextPage = Nothing(); |
1131 | mFreePageListTail = Some(aIndex); |
1132 | } |
1133 | |
1134 | private: |
1135 | template <int N> |
1136 | uint64_t RandomSeed() { |
1137 | // An older version of this code used RandomUint64() here, but on Mac that |
1138 | // function uses arc4random(), which can allocate, which would cause |
1139 | // re-entry, which would be bad. So we just use time(), a local variable |
1140 | // address and a global variable address. These are mediocre sources of |
1141 | // entropy, but good enough for PHC. |
1142 | static_assert(N == 0 || N == 1 || N == 2, "must be 0, 1 or 2"); |
1143 | uint64_t seed; |
1144 | if (N == 0) { |
1145 | time_t t = time(nullptr); |
1146 | seed = t ^ (t << 32); |
1147 | } else if (N == 1) { |
1148 | seed = uintptr_t(&seed) ^ (uintptr_t(&seed) << 32); |
1149 | } else { |
1150 | seed = uintptr_t(&sRegion) ^ (uintptr_t(&sRegion) << 32); |
1151 | } |
1152 | return seed; |
1153 | } |
1154 | |
1155 | public: |
1156 | // Attempt a page allocation if the time and the size are right. Allocated |
1157 | // memory is zeroed if aZero is true. On failure, the caller should attempt a |
1158 | // normal allocation via MozJemalloc. Can be called in a context where |
1159 | // PHC::mMutex is locked. |
1160 | void* MaybePageAlloc(const Maybe<arena_id_t>& aArenaId, size_t aReqSize, |
1161 | size_t aAlignment, bool aZero); |
1162 | |
1163 | void FreePage(uintptr_t aIndex, const Maybe<arena_id_t>& aArenaId, |
1164 | const StackTrace& aFreeStack, Delay aReuseDelay); |
1165 | |
1166 | // This handles both free and moz_arena_free. |
1167 | void PageFree(const Maybe<arena_id_t>& aArenaId, void* aPtr); |
1168 | |
1169 | Maybe<void*> PageRealloc(const Maybe<arena_id_t>& aArenaId, void* aOldPtr, |
1170 | size_t aNewSize); |
1171 | |
1172 | void PagePtrInfo(const void* aPtr, jemalloc_ptr_info_t* aInfo); |
1173 | |
1174 | size_t PtrUsableSize(usable_ptr_t aPtr); |
1175 | |
1176 | bool IsPHCAllocation(const void* aPtr, mozilla::phc::AddrInfo* aOut); |
1177 | |
1178 | void Crash(const char* aMessage); |
1179 | |
1180 | private: |
1181 | // To improve locality we try to order this file by how frequently different |
1182 | // fields are modified and place all the modified-together fields early and |
1183 | // ideally within a single cache line. |
1184 | // The mutex that protects the other members. |
1185 | alignas(kCacheLineSize) Mutex mMutex MOZ_UNANNOTATED; |
1186 | |
1187 | // The current time. We use ReleaseAcquire semantics since we attempt to |
1188 | // update this by larger increments and don't want to lose an entire update. |
1189 | Atomic<Time, ReleaseAcquire> mNow; |
1190 | |
1191 | // This will only ever be updated from one thread. The other threads should |
1192 | // eventually get the update. |
1193 | Atomic<PHCState, Relaxed> mPhcState = |
1194 | Atomic<PHCState, Relaxed>(DEFAULT_STATEmozilla::phc::OnlyFree); |
1195 | |
1196 | // RNG for deciding which allocations to treat specially. It doesn't need to |
1197 | // be high quality. |
1198 | // |
1199 | // This is a raw pointer for the reason explained in the comment above |
1200 | // PHC's constructor. Don't change it to UniquePtr or anything like that. |
1201 | non_crypto::XorShift128PlusRNG mRNG MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))); |
1202 | |
1203 | // A linked list of free pages. Pages are allocated from the head of the list |
1204 | // and returned to the tail. The list will naturally order itself by "last |
1205 | // freed time" so if the head of the list can't satisfy an allocation due to |
1206 | // time then none of the pages can. |
1207 | Maybe<uintptr_t> mFreePageListHead MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))); |
1208 | Maybe<uintptr_t> mFreePageListTail MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))); |
1209 | |
1210 | #if PHC_LOGGING0 |
1211 | // How many allocations that could have been page allocs actually were? As |
1212 | // constrained kNumAllocPages. If the hit ratio isn't close to 100% it's |
1213 | // likely that the global constants are poorly chosen. |
1214 | size_t mPageAllocHits MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))) = 0; |
1215 | size_t mPageAllocMisses MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))) = 0; |
1216 | #endif |
1217 | |
1218 | // The remaining fields are updated much less often, place them on the next |
1219 | // cache line. |
1220 | |
1221 | // The average delay before doing any page allocations at the start of a |
1222 | // process. Note that roughly 1 million allocations occur in the main process |
1223 | // while starting the browser. The delay range is 1..gAvgFirstAllocDelay*2. |
1224 | alignas(kCacheLineSize) Delay mAvgFirstAllocDelay |
1225 | MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))) = 64 * 1024; |
1226 | |
1227 | // The average delay until the next attempted page allocation, once we get |
1228 | // past the first delay. The delay range is 1..kAvgAllocDelay*2. |
1229 | Delay mAvgAllocDelay MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))) = 16 * 1024; |
1230 | |
1231 | // The average delay before reusing a freed page. Should be significantly |
1232 | // larger than kAvgAllocDelay, otherwise there's not much point in having it. |
1233 | // The delay range is (kAvgAllocDelay / 2)..(kAvgAllocDelay / 2 * 3). This is |
1234 | // different to the other delay ranges in not having a minimum of 1, because |
1235 | // that's such a short delay that there is a high likelihood of bad stacks in |
1236 | // any crash report. |
1237 | Delay mAvgPageReuseDelay MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))) = 256 * 1024; |
1238 | |
1239 | // When true, PHC does as little as possible. |
1240 | // |
1241 | // (a) It does not allocate any new page allocations. |
1242 | // |
1243 | // (b) It avoids doing any operations that might call malloc/free/etc., which |
1244 | // would cause re-entry into PHC. (In practice, MozStackWalk() is the |
1245 | // only such operation.) Note that calls to the functions in MozJemalloc |
1246 | // are ok. |
1247 | // |
1248 | // For example, replace_malloc() will just fall back to mozjemalloc. However, |
1249 | // operations involving existing allocations are more complex, because those |
1250 | // existing allocations may be page allocations. For example, if |
1251 | // replace_free() is passed a page allocation on a PHC-disabled thread, it |
1252 | // will free the page allocation in the usual way, but it will get a dummy |
1253 | // freeStack in order to avoid calling MozStackWalk(), as per (b) above. |
1254 | // |
1255 | // This single disabling mechanism has two distinct uses. |
1256 | // |
1257 | // - It's used to prevent re-entry into PHC, which can cause correctness |
1258 | // problems. For example, consider this sequence. |
1259 | // |
1260 | // 1. enter replace_free() |
1261 | // 2. which calls PageFree() |
1262 | // 3. which calls MozStackWalk() |
1263 | // 4. which locks a mutex M, and then calls malloc |
1264 | // 5. enter replace_malloc() |
1265 | // 6. which calls MaybePageAlloc() |
1266 | // 7. which calls MozStackWalk() |
1267 | // 8. which (re)locks a mutex M --> deadlock |
1268 | // |
1269 | // We avoid this sequence by "disabling" the thread in PageFree() (at step |
1270 | // 2), which causes MaybePageAlloc() to fail, avoiding the call to |
1271 | // MozStackWalk() (at step 7). |
1272 | // |
1273 | // In practice, realloc or free of a PHC allocation is unlikely on a thread |
1274 | // that is disabled because of this use: MozStackWalk() will probably only |
1275 | // realloc/free allocations that it allocated itself, but those won't be |
1276 | // page allocations because PHC is disabled before calling MozStackWalk(). |
1277 | // |
1278 | // (Note that MaybePageAlloc() could safely do a page allocation so long as |
1279 | // it avoided calling MozStackWalk() by getting a dummy allocStack. But it |
1280 | // wouldn't be useful, and it would prevent the second use below.) |
1281 | // |
1282 | // - It's used to prevent PHC allocations in some tests that rely on |
1283 | // mozjemalloc's exact allocation behaviour, which PHC does not replicate |
1284 | // exactly. (Note that (b) isn't necessary for this use -- MozStackWalk() |
1285 | // could be safely called -- but it is necessary for the first use above.) |
1286 | // |
1287 | static PHC_THREAD_LOCAL(bool)__thread ::mozilla::detail::ThreadLocal< bool, ::mozilla:: detail::ThreadLocalNativeStorage> tlsIsDisabled; |
1288 | |
1289 | // Delay until the next attempt at a page allocation. The delay is made up of |
1290 | // two parts the global delay and each thread's local portion of that delay: |
1291 | // |
1292 | // delay = sDelay + sum_all_threads(tlsAllocDelay) |
1293 | // |
1294 | // Threads use their local delay to reduce contention on the shared delay. |
1295 | // |
1296 | // See the comment in MaybePageAlloc() for an explanation of why it uses |
1297 | // ReleaseAcquire semantics. |
1298 | static Atomic<Delay, ReleaseAcquire> sAllocDelay; |
1299 | static PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> tlsAllocDelay; |
1300 | |
1301 | // The last value we set tlsAllocDelay to before starting to count down. |
1302 | static PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> tlsLastDelay; |
1303 | |
1304 | // Using mfbt/Array.h makes MOZ_GUARDED_BY more reliable than a C array. |
1305 | Array<AllocPageInfo, kNumAllocPages> mAllocPages MOZ_GUARDED_BY(mMutex)__attribute__((guarded_by(mMutex))); |
1306 | |
1307 | public: |
1308 | Delay GetAvgAllocDelay() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { return mAvgAllocDelay; } |
1309 | Delay GetAvgFirstAllocDelay() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1310 | return mAvgFirstAllocDelay; |
1311 | } |
1312 | Delay GetAvgPageReuseDelay() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1313 | return mAvgPageReuseDelay; |
1314 | } |
1315 | Delay ReuseDelay() MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1316 | Delay avg_reuse_delay = GetAvgPageReuseDelay(); |
1317 | return (avg_reuse_delay / 2) + |
1318 | Rnd64ToDelay(avg_reuse_delay / 2, Random64()); |
1319 | } |
1320 | |
1321 | // Both of these are accessed early on hot code paths. We make them both |
1322 | // static variables rathan making sRegion a member of sPHC to keep these hot |
1323 | // code paths as fast as possible. They're both "write once" so they can |
1324 | // share a cache line. |
1325 | static PHCRegion sRegion; |
1326 | static PHC* sPHC; |
1327 | }; |
1328 | |
1329 | // These globals are read together and hardly ever written. They should be on |
1330 | // the same cache line. They should be in a different cache line to data that |
1331 | // is manipulated often (sMutex and mNow are members of sPHC for that reason) so |
1332 | // that this cache line can be shared amoung cores. This makes a measurable |
1333 | // impact to calls to maybe_init() |
1334 | alignas(kCacheLineSize) PHCRegion PHC::sRegion; |
1335 | PHC* PHC::sPHC; |
1336 | |
1337 | PHC_THREAD_LOCAL(bool)__thread ::mozilla::detail::ThreadLocal< bool, ::mozilla:: detail::ThreadLocalNativeStorage> PHC::tlsIsDisabled; |
1338 | PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> PHC::tlsAllocDelay; |
1339 | Atomic<Delay, ReleaseAcquire> PHC::sAllocDelay; |
1340 | PHC_THREAD_LOCAL(Delay)__thread ::mozilla::detail::ThreadLocal< Delay, ::mozilla:: detail::ThreadLocalNativeStorage> PHC::tlsLastDelay; |
1341 | |
1342 | // When PHC wants to crash we first have to unlock so that the crash reporter |
1343 | // can call into PHC to lockup its pointer. That also means that before calling |
1344 | // PHCCrash please ensure that state is consistent. Because this can report an |
1345 | // arbitrary string, use of it must be reviewed by Firefox data stewards. |
1346 | void PHC::Crash(const char* aMessage) MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1347 | mMutex.Unlock(); |
1348 | MOZ_CRASH_UNSAFE(aMessage)MOZ_Crash("/root/firefox-clang/memory/build/PHC.cpp", 1348, aMessage ); |
1349 | } |
1350 | |
1351 | class AutoDisableOnCurrentThread { |
1352 | public: |
1353 | AutoDisableOnCurrentThread(const AutoDisableOnCurrentThread&) = delete; |
1354 | |
1355 | const AutoDisableOnCurrentThread& operator=( |
1356 | const AutoDisableOnCurrentThread&) = delete; |
1357 | |
1358 | explicit AutoDisableOnCurrentThread() { PHC::DisableOnCurrentThread(); } |
1359 | ~AutoDisableOnCurrentThread() { PHC::sPHC->EnableOnCurrentThread(); } |
1360 | }; |
1361 | |
1362 | //--------------------------------------------------------------------------- |
1363 | // Initialisation |
1364 | //--------------------------------------------------------------------------- |
1365 | |
1366 | // WARNING: this function runs *very* early -- before all static initializers |
1367 | // have run. For this reason, non-scalar globals (sPHC) are allocated |
1368 | // dynamically (so we can guarantee their construction in this function) rather |
1369 | // than statically. sRegion is allocated statically to avoid an extra |
1370 | // dereference. |
1371 | static bool phc_init() { |
1372 | if (GetKernelPageSize() != kPageSize) { |
1373 | return false; |
1374 | } |
1375 | |
1376 | if (!PHC::sRegion.AllocVirtualAddresses()) { |
1377 | return false; |
1378 | } |
1379 | |
1380 | // sPHC is never freed. It lives for the life of the process. |
1381 | PHC::sPHC = InfallibleAllocPolicy::new_<PHC>(); |
1382 | |
1383 | #ifndef XP_WIN |
1384 | // Avoid deadlocks when forking by acquiring our state lock prior to forking |
1385 | // and releasing it after forking. See |LogAlloc|'s |phc_init| for |
1386 | // in-depth details. |
1387 | pthread_atfork(PHC::prefork, PHC::postfork_parent, PHC::postfork_child); |
1388 | #endif |
1389 | |
1390 | return true; |
1391 | } |
1392 | |
1393 | static inline bool maybe_init() { |
1394 | // This runs on hot paths and we can save some memory accesses by using sPHC |
1395 | // to test if we've already initialised PHC successfully. |
1396 | if (MOZ_UNLIKELY(!PHC::sPHC)(__builtin_expect(!!(!PHC::sPHC), 0))) { |
1397 | // The lambda will only be called once and is thread safe. |
1398 | static bool sInitSuccess = []() { return phc_init(); }(); |
1399 | return sInitSuccess; |
1400 | } |
1401 | |
1402 | return true; |
1403 | } |
1404 | |
1405 | //--------------------------------------------------------------------------- |
1406 | // Page allocation operations |
1407 | //--------------------------------------------------------------------------- |
1408 | |
1409 | // This is the hot-path for testing if we should make a PHC allocation, it |
1410 | // should be inlined into the caller while the remainder of the tests that are |
1411 | // in MaybePageAlloc need not be inlined. |
1412 | static MOZ_ALWAYS_INLINEinline bool ShouldPageAllocHot(size_t aReqSize) { |
1413 | if (MOZ_UNLIKELY(!maybe_init())(__builtin_expect(!!(!maybe_init()), 0))) { |
1414 | return false; |
1415 | } |
1416 | |
1417 | if (MOZ_UNLIKELY(aReqSize > kPageSize)(__builtin_expect(!!(aReqSize > kPageSize), 0))) { |
1418 | return false; |
1419 | } |
1420 | |
1421 | // Decrement the delay. If it's zero, we do a page allocation and reset the |
1422 | // delay to a random number. |
1423 | if (MOZ_LIKELY(!PHC::DecrementDelay())(__builtin_expect(!!(!PHC::DecrementDelay()), 1))) { |
1424 | return false; |
1425 | } |
1426 | |
1427 | return true; |
1428 | } |
1429 | |
1430 | void PHC::LogNoAlloc(size_t aReqSize, size_t aAlignment, Delay newAllocDelay) |
1431 | MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1432 | // No pages are available, or VirtualAlloc/mprotect failed. |
1433 | #if PHC_LOGGING0 |
1434 | phc::PHCStats stats = GetPageStatsLocked(); |
1435 | Log("No PageAlloc(%zu, %zu), sAllocDelay <- %zu, fullness %zu/%zu/%zu, " |
1436 | "hits %zu/%zu (%zu%%)\n", |
1437 | aReqSize, aAlignment, size_t(newAllocDelay), stats.mSlotsAllocated, |
1438 | stats.mSlotsFreed, kNumAllocPages, PageAllocHits(), PageAllocAttempts(), |
1439 | PageAllocHitRate()); |
1440 | #endif |
1441 | } |
1442 | |
1443 | void* PHC::MaybePageAlloc(const Maybe<arena_id_t>& aArenaId, size_t aReqSize, |
1444 | size_t aAlignment, bool aZero) { |
1445 | 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)" , "/root/firefox-clang/memory/build/PHC.cpp", 1445); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "IsPowerOfTwo(aAlignment)" ")"); do { MOZ_CrashSequence (__null, 1445); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1446 | if (!ShouldMakeNewAllocations()) { |
1447 | // Reset the allocation delay so that we take the fast path most of the |
1448 | // time. Rather than take the lock and use the RNG which are unnecessary |
1449 | // when PHC is disabled, instead set the delay to a reasonably high number, |
1450 | // the default average first allocation delay. This is reset when PHC is |
1451 | // re-enabled anyway. |
1452 | ForceSetNewAllocDelay(kDelayResetWhenDisabled); |
1453 | return nullptr; |
1454 | } |
1455 | |
1456 | if (IsDisabledOnCurrentThread()) { |
1457 | // We don't reset sAllocDelay since that might affect other threads. We |
1458 | // assume this is okay because either this thread will be re-enabled after |
1459 | // less than DELAY_MAX allocations or that there are other active threads |
1460 | // that will reset sAllocDelay. We do reset our local delay which will |
1461 | // cause this thread to "back off" from updating sAllocDelay on future |
1462 | // allocations. |
1463 | ResetLocalAllocDelay(kDelayBackoffAmount); |
1464 | return nullptr; |
1465 | } |
1466 | |
1467 | // Disable on this thread *before* getting the stack trace. |
1468 | AutoDisableOnCurrentThread disable; |
1469 | |
1470 | // Get the stack trace *before* locking the mutex. If we return nullptr then |
1471 | // it was a waste, but it's not so frequent, and doing a stack walk while |
1472 | // the mutex is locked is problematic (see the big comment on |
1473 | // StackTrace::Fill() for details). |
1474 | StackTrace allocStack; |
1475 | allocStack.Fill(); |
1476 | |
1477 | MutexAutoLock lock(mMutex); |
1478 | |
1479 | Time now = Now(); |
1480 | |
1481 | Delay newAllocDelay = Rnd64ToDelay(GetAvgAllocDelay(), Random64()); |
1482 | if (!SetNewAllocDelay(newAllocDelay)) { |
1483 | return nullptr; |
1484 | } |
1485 | |
1486 | // Pages are allocated from a free list populated in order of when they're |
1487 | // freed. If the page at the head of the list is too recently freed to be |
1488 | // reused then no other pages on the list will be either. |
1489 | |
1490 | Maybe<uintptr_t> mb_index = PopNextFreeIfAllocatable(now); |
1491 | if (!mb_index) { |
1492 | IncPageAllocMisses(); |
1493 | LogNoAlloc(aReqSize, aAlignment, newAllocDelay); |
1494 | return nullptr; |
1495 | } |
1496 | uintptr_t index = mb_index.value(); |
1497 | |
1498 | #if PHC_LOGGING0 |
1499 | Time lifetime = 0; |
1500 | #endif |
1501 | uint8_t* pagePtr = sRegion.AllocPagePtr(index); |
1502 | 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", "/root/firefox-clang/memory/build/PHC.cpp" , 1502); AnnotateMozCrashReason("MOZ_ASSERT" "(" "pagePtr" ")" ); do { MOZ_CrashSequence(__null, 1502); __attribute__((nomerge )) ::abort(); } while (false); } } while (false); |
1503 | bool ok = |
1504 | #ifdef XP_WIN |
1505 | !!VirtualAlloc(pagePtr, kPageSize, MEM_COMMIT, PAGE_READWRITE); |
1506 | #else |
1507 | mprotect(pagePtr, kPageSize, PROT_READ0x1 | PROT_WRITE0x2) == 0; |
1508 | #endif |
1509 | |
1510 | if (!ok) { |
1511 | UnpopNextFree(index); |
1512 | IncPageAllocMisses(); |
1513 | LogNoAlloc(aReqSize, aAlignment, newAllocDelay); |
1514 | return nullptr; |
1515 | } |
1516 | |
1517 | size_t usableSize = MozJemalloc::malloc_good_size(aReqSize); |
1518 | 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" , "/root/firefox-clang/memory/build/PHC.cpp", 1518); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "usableSize > 0" ")"); do { MOZ_CrashSequence (__null, 1518); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1519 | |
1520 | // Put the allocation as close to the end of the page as possible, |
1521 | // allowing for alignment requirements. |
1522 | uint8_t* ptr = pagePtr + kPageSize - usableSize; |
1523 | if (aAlignment != 1) { |
1524 | ptr = reinterpret_cast<uint8_t*>( |
1525 | (reinterpret_cast<uintptr_t>(ptr) & ~(aAlignment - 1))); |
1526 | } |
1527 | |
1528 | #if PHC_LOGGING0 |
1529 | Time then = GetFreeTime(index); |
1530 | lifetime = then != 0 ? now - then : 0; |
1531 | #endif |
1532 | |
1533 | SetPageInUse(index, aArenaId, ptr, allocStack); |
1534 | |
1535 | if (aZero) { |
1536 | memset(ptr, 0, usableSize); |
1537 | } else { |
1538 | #ifdef DEBUG1 |
1539 | memset(ptr, kAllocJunk, usableSize); |
1540 | #endif |
1541 | } |
1542 | |
1543 | IncPageAllocHits(); |
1544 | #if PHC_LOGGING0 |
1545 | phc::PHCStats stats = GetPageStatsLocked(); |
1546 | Log("PageAlloc(%zu, %zu) -> %p[%zu]/%p (%zu) (z%zu), sAllocDelay <- %zu, " |
1547 | "fullness %zu/%zu/%zu, hits %zu/%zu (%zu%%), lifetime %zu\n", |
1548 | aReqSize, aAlignment, pagePtr, index, ptr, usableSize, |
1549 | size_t(newAllocDelay), size_t(SharedAllocDelay()), stats.mSlotsAllocated, |
1550 | stats.mSlotsFreed, kNumAllocPages, PageAllocHits(), PageAllocAttempts(), |
1551 | PageAllocHitRate(), lifetime); |
1552 | #endif |
1553 | |
1554 | return ptr; |
1555 | } |
1556 | |
1557 | void PHC::FreePage(uintptr_t aIndex, const Maybe<arena_id_t>& aArenaId, |
1558 | const StackTrace& aFreeStack, Delay aReuseDelay) |
1559 | MOZ_REQUIRES(mMutex)__attribute__((exclusive_locks_required(mMutex))) { |
1560 | void* pagePtr = sRegion.AllocPagePtr(aIndex); |
1561 | |
1562 | #ifdef XP_WIN |
1563 | if (!VirtualFree(pagePtr, kPageSize, MEM_DECOMMIT)) { |
1564 | Crash("VirtualFree failed"); |
1565 | } |
1566 | #else |
1567 | if (mmap_mmap(pagePtr, kPageSize, PROT_NONE0x0, MAP_FIXED0x10 | MAP_PRIVATE0x02 | MAP_ANON0x20, |
1568 | -1, 0) == MAP_FAILED((void *) -1)) { |
1569 | Crash("mmap failed"); |
1570 | } |
1571 | #endif |
1572 | |
1573 | SetPageFreed(aIndex, aArenaId, aFreeStack, aReuseDelay); |
1574 | } |
1575 | |
1576 | //--------------------------------------------------------------------------- |
1577 | // replace-malloc machinery |
1578 | //--------------------------------------------------------------------------- |
1579 | |
1580 | // This handles malloc, moz_arena_malloc, and realloc-with-a-nullptr. |
1581 | MOZ_ALWAYS_INLINEinline static void* PageMalloc(const Maybe<arena_id_t>& aArenaId, |
1582 | size_t aReqSize) { |
1583 | void* ptr = |
1584 | ShouldPageAllocHot(aReqSize) |
1585 | // The test on aArenaId here helps the compiler optimise away |
1586 | // the construction of Nothing() in the caller. |
1587 | ? PHC::sPHC->MaybePageAlloc(aArenaId.isSome() ? aArenaId : Nothing(), |
1588 | aReqSize, /* aAlignment */ 1, |
1589 | /* aZero */ false) |
1590 | : nullptr; |
1591 | return ptr ? ptr |
1592 | : (aArenaId.isSome() |
1593 | ? MozJemalloc::moz_arena_malloc(*aArenaId, aReqSize) |
1594 | : MozJemalloc::malloc(aReqSize)); |
1595 | } |
1596 | |
1597 | inline void* MozJemallocPHC::malloc(size_t aReqSize) { |
1598 | return PageMalloc(Nothing(), aReqSize); |
1599 | } |
1600 | |
1601 | // This handles both calloc and moz_arena_calloc. |
1602 | MOZ_ALWAYS_INLINEinline static void* PageCalloc(const Maybe<arena_id_t>& aArenaId, |
1603 | size_t aNum, size_t aReqSize) { |
1604 | CheckedInt<size_t> checkedSize = CheckedInt<size_t>(aNum) * aReqSize; |
1605 | if (!checkedSize.isValid()) { |
1606 | return nullptr; |
1607 | } |
1608 | |
1609 | void* ptr = |
1610 | ShouldPageAllocHot(checkedSize.value()) |
1611 | // The test on aArenaId here helps the compiler optimise away |
1612 | // the construction of Nothing() in the caller. |
1613 | ? PHC::sPHC->MaybePageAlloc(aArenaId.isSome() ? aArenaId : Nothing(), |
1614 | checkedSize.value(), /* aAlignment */ 1, |
1615 | /* aZero */ true) |
1616 | : nullptr; |
1617 | return ptr ? ptr |
1618 | : (aArenaId.isSome() |
1619 | ? MozJemalloc::moz_arena_calloc(*aArenaId, aNum, aReqSize) |
1620 | : MozJemalloc::calloc(aNum, aReqSize)); |
1621 | } |
1622 | |
1623 | inline void* MozJemallocPHC::calloc(size_t aNum, size_t aReqSize) { |
1624 | return PageCalloc(Nothing(), aNum, aReqSize); |
1625 | } |
1626 | |
1627 | MOZ_ALWAYS_INLINEinline static bool FastIsPHCPtr(const void* aPtr) { |
1628 | if (MOZ_UNLIKELY(!maybe_init())(__builtin_expect(!!(!maybe_init()), 0))) { |
1629 | return false; |
1630 | } |
1631 | |
1632 | PtrKind pk = PHC::sRegion.PtrKind(aPtr); |
1633 | return !pk.IsNothing(); |
1634 | } |
1635 | |
1636 | // This function handles both realloc and moz_arena_realloc. |
1637 | // |
1638 | // As always, realloc is complicated, and doubly so when there are two |
1639 | // different kinds of allocations in play. Here are the possible transitions, |
1640 | // and what we do in practice. |
1641 | // |
1642 | // - normal-to-normal: This is straightforward and obviously necessary. |
1643 | // |
1644 | // - normal-to-page: This is disallowed because it would require getting the |
1645 | // arenaId of the normal allocation, which isn't possible in non-DEBUG builds |
1646 | // for security reasons. |
1647 | // |
1648 | // - page-to-page: This is done whenever possible, i.e. whenever the new size |
1649 | // is less than or equal to 4 KiB. This choice counterbalances the |
1650 | // disallowing of normal-to-page allocations, in order to avoid biasing |
1651 | // towards or away from page allocations. It always occurs in-place. |
1652 | // |
1653 | // - page-to-normal: this is done only when necessary, i.e. only when the new |
1654 | // size is greater than 4 KiB. This choice naturally flows from the |
1655 | // prior choice on page-to-page transitions. |
1656 | // |
1657 | // In summary: realloc doesn't change the allocation kind unless it must. |
1658 | // |
1659 | // This function may return: |
1660 | // - Some(pointer) when PHC handled the reallocation. |
1661 | // - Some(nullptr) when PHC should have handled a page-to-normal transition |
1662 | // but couldn't because of OOM. |
1663 | // - Nothing() when PHC is disabled or the original allocation was not |
1664 | // under PHC. |
1665 | MOZ_ALWAYS_INLINEinline static Maybe<void*> MaybePageRealloc( |
1666 | const Maybe<arena_id_t>& aArenaId, void* aOldPtr, size_t aNewSize) { |
1667 | if (!aOldPtr) { |
1668 | // Null pointer. Treat like malloc(aNewSize). |
1669 | return Some(PageMalloc(aArenaId, aNewSize)); |
1670 | } |
1671 | |
1672 | if (!FastIsPHCPtr(aOldPtr)) { |
1673 | // A normal-to-normal transition. |
1674 | return Nothing(); |
1675 | } |
1676 | |
1677 | return PHC::sPHC->PageRealloc(aArenaId, aOldPtr, aNewSize); |
1678 | } |
1679 | |
1680 | Maybe<void*> PHC::PageRealloc(const Maybe<arena_id_t>& aArenaId, void* aOldPtr, |
1681 | size_t aNewSize) MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
1682 | PtrKind pk = sRegion.PtrKind(aOldPtr); |
1683 | MOZ_ASSERT(!pk.IsNothing())do { static_assert( mozilla::detail::AssertionConditionType< decltype(!pk.IsNothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!pk.IsNothing()))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!pk.IsNothing()" , "/root/firefox-clang/memory/build/PHC.cpp", 1683); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!pk.IsNothing()" ")"); do { MOZ_CrashSequence (__null, 1683); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1684 | |
1685 | if (pk.IsGuardPage()) { |
1686 | CrashOnGuardPage(aOldPtr); |
1687 | } |
1688 | |
1689 | // At this point we know we have an allocation page. |
1690 | uintptr_t index = pk.AllocPageIndex(); |
1691 | |
1692 | // A page-to-something transition. |
1693 | AdvanceNow(LocalAllocDelay()); |
1694 | |
1695 | // Note that `disable` has no effect unless it is emplaced below. |
1696 | Maybe<AutoDisableOnCurrentThread> disable; |
1697 | // Get the stack trace *before* locking the mutex. |
1698 | StackTrace stack; |
1699 | if (IsDisabledOnCurrentThread()) { |
1700 | // PHC is disabled on this thread. Leave the stack empty. |
1701 | } else { |
1702 | // Disable on this thread *before* getting the stack trace. |
1703 | disable.emplace(); |
1704 | stack.Fill(); |
1705 | } |
1706 | |
1707 | MutexAutoLock lock(mMutex); |
1708 | |
1709 | // Check for realloc() of a freed block. |
1710 | EnsureValidAndInUse(aOldPtr, index); |
1711 | |
1712 | if (aNewSize <= kPageSize && ShouldMakeNewAllocations()) { |
1713 | // A page-to-page transition. Just keep using the page allocation. We do |
1714 | // this even if the thread is disabled, because it doesn't create a new |
1715 | // page allocation. Note that ResizePageInUse() checks aArenaId. |
1716 | // |
1717 | // Move the bytes with memmove(), because the old allocation and the new |
1718 | // allocation overlap. Move the usable size rather than the requested size, |
1719 | // because the user might have used malloc_usable_size() and filled up the |
1720 | // usable size. |
1721 | size_t oldUsableSize = PageUsableSize(index); |
1722 | size_t newUsableSize = MozJemalloc::malloc_good_size(aNewSize); |
1723 | uint8_t* pagePtr = sRegion.AllocPagePtr(index); |
1724 | uint8_t* newPtr = pagePtr + kPageSize - newUsableSize; |
1725 | memmove(newPtr, aOldPtr, std::min(oldUsableSize, aNewSize)); |
1726 | ResizePageInUse(index, aArenaId, newPtr, stack); |
1727 | Log("PageRealloc-Reuse(%p, %zu) -> %p\n", aOldPtr, aNewSize, newPtr); |
1728 | return Some(newPtr); |
1729 | } |
1730 | |
1731 | // A page-to-normal transition (with the new size greater than page-sized). |
1732 | // (Note that aArenaId is checked below.) |
1733 | void* newPtr; |
1734 | if (aArenaId.isSome()) { |
1735 | newPtr = MozJemalloc::moz_arena_malloc(*aArenaId, aNewSize); |
1736 | } else { |
1737 | Maybe<arena_id_t> oldArenaId = PageArena(index); |
1738 | newPtr = (oldArenaId.isSome() |
1739 | ? MozJemalloc::moz_arena_malloc(*oldArenaId, aNewSize) |
1740 | : MozJemalloc::malloc(aNewSize)); |
1741 | } |
1742 | if (!newPtr) { |
1743 | return Some(nullptr); |
1744 | } |
1745 | |
1746 | Delay reuseDelay = ReuseDelay(); |
1747 | |
1748 | // Copy the usable size rather than the requested size, because the user |
1749 | // might have used malloc_usable_size() and filled up the usable size. Note |
1750 | // that FreePage() checks aArenaId (via SetPageFreed()). |
1751 | size_t oldUsableSize = PageUsableSize(index); |
1752 | memcpy(newPtr, aOldPtr, std::min(oldUsableSize, aNewSize)); |
1753 | FreePage(index, aArenaId, stack, reuseDelay); |
1754 | Log("PageRealloc-Free(%p[%zu], %zu) -> %p, %zu delay, reuse at ~%zu\n", |
1755 | aOldPtr, index, aNewSize, newPtr, size_t(reuseDelay), |
1756 | size_t(Now()) + reuseDelay); |
1757 | |
1758 | return Some(newPtr); |
1759 | } |
1760 | |
1761 | MOZ_ALWAYS_INLINEinline static void* PageRealloc(const Maybe<arena_id_t>& aArenaId, |
1762 | void* aOldPtr, size_t aNewSize) { |
1763 | Maybe<void*> ptr = MaybePageRealloc(aArenaId, aOldPtr, aNewSize); |
1764 | |
1765 | return ptr.isSome() |
1766 | ? *ptr |
1767 | : (aArenaId.isSome() ? MozJemalloc::moz_arena_realloc( |
1768 | *aArenaId, aOldPtr, aNewSize) |
1769 | : MozJemalloc::realloc(aOldPtr, aNewSize)); |
1770 | } |
1771 | |
1772 | inline void* MozJemallocPHC::realloc(void* aOldPtr, size_t aNewSize) { |
1773 | return PageRealloc(Nothing(), aOldPtr, aNewSize); |
1774 | } |
1775 | |
1776 | void PHC::PageFree(const Maybe<arena_id_t>& aArenaId, void* aPtr) |
1777 | MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
1778 | PtrKind pk = sRegion.PtrKind(aPtr); |
1779 | MOZ_ASSERT(!pk.IsNothing())do { static_assert( mozilla::detail::AssertionConditionType< decltype(!pk.IsNothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!pk.IsNothing()))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!pk.IsNothing()" , "/root/firefox-clang/memory/build/PHC.cpp", 1779); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!pk.IsNothing()" ")"); do { MOZ_CrashSequence (__null, 1779); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
1780 | if (pk.IsGuardPage()) { |
1781 | PHC::CrashOnGuardPage(aPtr); |
1782 | } |
1783 | |
1784 | // At this point we know we have an allocation page. |
1785 | AdvanceNow(LocalAllocDelay()); |
1786 | uintptr_t index = pk.AllocPageIndex(); |
1787 | |
1788 | // Note that `disable` has no effect unless it is emplaced below. |
1789 | Maybe<AutoDisableOnCurrentThread> disable; |
1790 | // Get the stack trace *before* locking the mutex. |
1791 | StackTrace freeStack; |
1792 | if (IsDisabledOnCurrentThread()) { |
1793 | // PHC is disabled on this thread. Leave the stack empty. |
1794 | } else { |
1795 | // Disable on this thread *before* getting the stack trace. |
1796 | disable.emplace(); |
1797 | freeStack.Fill(); |
1798 | } |
1799 | |
1800 | MutexAutoLock lock(mMutex); |
1801 | |
1802 | // Check for a double-free. |
1803 | EnsureValidAndInUse(aPtr, index); |
1804 | |
1805 | // Note that FreePage() checks aArenaId (via SetPageFreed()). |
1806 | Delay reuseDelay = ReuseDelay(); |
1807 | FreePage(index, aArenaId, freeStack, reuseDelay); |
1808 | |
1809 | #if PHC_LOGGING0 |
1810 | phc::PHCStats stats = GetPageStatsLocked(); |
1811 | Log("PageFree(%p[%zu]), %zu delay, reuse at ~%zu, fullness %zu/%zu/%zu\n", |
1812 | aPtr, index, size_t(reuseDelay), size_t(Now()) + reuseDelay, |
1813 | stats.mSlotsAllocated, stats.mSlotsFreed, kNumAllocPages); |
1814 | #endif |
1815 | } |
1816 | |
1817 | MOZ_ALWAYS_INLINEinline static void PageFree(const Maybe<arena_id_t>& aArenaId, |
1818 | void* aPtr) { |
1819 | if (MOZ_UNLIKELY(FastIsPHCPtr(aPtr))(__builtin_expect(!!(FastIsPHCPtr(aPtr)), 0))) { |
1820 | // The tenery expression here helps the compiler optimise away the |
1821 | // construction of Nothing() in the caller. |
1822 | PHC::sPHC->PageFree(aArenaId.isSome() ? aArenaId : Nothing(), aPtr); |
1823 | return; |
1824 | } |
1825 | |
1826 | aArenaId.isSome() ? MozJemalloc::moz_arena_free(*aArenaId, aPtr) |
1827 | : MozJemalloc::free(aPtr); |
1828 | } |
1829 | |
1830 | inline void MozJemallocPHC::free(void* aPtr) { PageFree(Nothing(), aPtr); } |
1831 | |
1832 | // This handles memalign and moz_arena_memalign. |
1833 | MOZ_ALWAYS_INLINEinline static void* PageMemalign(const Maybe<arena_id_t>& aArenaId, |
1834 | size_t aAlignment, |
1835 | size_t aReqSize) { |
1836 | 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)" , "/root/firefox-clang/memory/build/PHC.cpp", 1836); AnnotateMozCrashReason ("MOZ_RELEASE_ASSERT" "(" "IsPowerOfTwo(aAlignment)" ")"); do { MOZ_CrashSequence(__null, 1836); __attribute__((nomerge)) :: abort(); } while (false); } } while (false); |
1837 | |
1838 | // PHC can't satisfy an alignment greater than a page size, so fall back to |
1839 | // mozjemalloc in that case. |
1840 | void* ptr = nullptr; |
1841 | if (ShouldPageAllocHot(aReqSize) && aAlignment <= kPageSize) { |
1842 | // The test on aArenaId here helps the compiler optimise away |
1843 | // the construction of Nothing() in the caller. |
1844 | ptr = PHC::sPHC->MaybePageAlloc(aArenaId.isSome() ? aArenaId : Nothing(), |
1845 | aReqSize, aAlignment, /* aZero */ false); |
1846 | } |
1847 | return ptr ? ptr |
1848 | : (aArenaId.isSome() |
1849 | ? MozJemalloc::moz_arena_memalign(*aArenaId, aAlignment, |
1850 | aReqSize) |
1851 | : MozJemalloc::memalign(aAlignment, aReqSize)); |
1852 | } |
1853 | |
1854 | inline void* MozJemallocPHC::memalign(size_t aAlignment, size_t aReqSize) { |
1855 | return PageMemalign(Nothing(), aAlignment, aReqSize); |
1856 | } |
1857 | |
1858 | inline size_t MozJemallocPHC::malloc_usable_size(usable_ptr_t aPtr) { |
1859 | if (!FastIsPHCPtr(aPtr)) { |
1860 | // Not a page allocation. Measure it normally. |
1861 | return MozJemalloc::malloc_usable_size(aPtr); |
1862 | } |
1863 | |
1864 | return PHC::sPHC->PtrUsableSize(aPtr); |
1865 | } |
1866 | |
1867 | size_t PHC::PtrUsableSize(usable_ptr_t aPtr) MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
1868 | PtrKind pk = sRegion.PtrKind(aPtr); |
1869 | if (pk.IsGuardPage()) { |
1870 | CrashOnGuardPage(const_cast<void*>(aPtr)); |
1871 | } |
1872 | |
1873 | // At this point we know aPtr lands within an allocation page, due to the |
1874 | // math done in the PtrKind constructor. But if aPtr points to memory |
1875 | // before the base address of the allocation, we return 0. |
1876 | uintptr_t index = pk.AllocPageIndex(); |
1877 | |
1878 | MutexAutoLock lock(mMutex); |
1879 | |
1880 | void* pageBaseAddr = AllocPageBaseAddr(index); |
1881 | |
1882 | if (MOZ_UNLIKELY(aPtr < pageBaseAddr)(__builtin_expect(!!(aPtr < pageBaseAddr), 0))) { |
1883 | return 0; |
1884 | } |
1885 | |
1886 | return PageUsableSize(index); |
1887 | } |
1888 | |
1889 | static size_t metadata_size() { |
1890 | return MozJemalloc::malloc_usable_size(PHC::sPHC); |
1891 | } |
1892 | |
1893 | inline void MozJemallocPHC::jemalloc_stats_internal( |
1894 | jemalloc_stats_t* aStats, jemalloc_bin_stats_t* aBinStats) { |
1895 | MozJemalloc::jemalloc_stats_internal(aStats, aBinStats); |
1896 | |
1897 | if (!maybe_init()) { |
1898 | // If we're not initialised, then we're not using any additional memory and |
1899 | // have nothing to add to the report. |
1900 | return; |
1901 | } |
1902 | |
1903 | // We allocate our memory from jemalloc so it has already counted our memory |
1904 | // usage within "mapped" and "allocated", we must subtract the memory we |
1905 | // allocated from jemalloc from allocated before adding in only the parts that |
1906 | // we have allocated out to Firefox. |
1907 | |
1908 | aStats->allocated -= kAllPagesJemallocSize; |
1909 | |
1910 | aStats->allocated += PHC::sPHC->AllocatedBytes(); |
1911 | |
1912 | // guards is the gap between `allocated` and `mapped`. In some ways this |
1913 | // almost fits into aStats->wasted since it feels like wasted memory. However |
1914 | // wasted should only include committed memory and these guard pages are |
1915 | // uncommitted. Therefore we don't include it anywhere. |
1916 | // size_t guards = mapped - allocated; |
1917 | |
1918 | // aStats.page_cache and aStats.bin_unused are left unchanged because PHC |
1919 | // doesn't have anything corresponding to those. |
1920 | |
1921 | // The metadata is stored in normal heap allocations, so they're measured by |
1922 | // mozjemalloc as `allocated`. Move them into `bookkeeping`. |
1923 | // They're also reported under explicit/heap-overhead/phc/fragmentation in |
1924 | // about:memory. |
1925 | size_t bookkeeping = metadata_size(); |
1926 | aStats->allocated -= bookkeeping; |
1927 | aStats->bookkeeping += bookkeeping; |
1928 | } |
1929 | |
1930 | inline void MozJemallocPHC::jemalloc_stats_lite(jemalloc_stats_lite_t* aStats) { |
1931 | MozJemalloc::jemalloc_stats_lite(aStats); |
1932 | } |
1933 | |
1934 | inline void MozJemallocPHC::jemalloc_ptr_info(const void* aPtr, |
1935 | jemalloc_ptr_info_t* aInfo) { |
1936 | if (!FastIsPHCPtr(aPtr)) { |
1937 | // Not a page allocation. |
1938 | MozJemalloc::jemalloc_ptr_info(aPtr, aInfo); |
1939 | return; |
1940 | } |
1941 | |
1942 | PHC::sPHC->PagePtrInfo(aPtr, aInfo); |
1943 | } |
1944 | |
1945 | void PHC::PagePtrInfo(const void* aPtr, jemalloc_ptr_info_t* aInfo) |
1946 | MOZ_EXCLUDES(mMutex)__attribute__((locks_excluded(mMutex))) { |
1947 | // We need to implement this properly, because various code locations do |
1948 | // things like checking that allocations are in the expected arena. |
1949 | |
1950 | PtrKind pk = sRegion.PtrKind(aPtr); |
1951 | if (pk.IsGuardPage()) { |
1952 | // Treat a guard page as unknown because there's no better alternative. |
1953 | *aInfo = {TagUnknown, nullptr, 0, 0}; |
1954 | return; |
1955 | } |
1956 | |
1957 | // At this point we know we have an allocation page. |
1958 | uintptr_t index = pk.AllocPageIndex(); |
1959 | |
1960 | MutexAutoLock lock(mMutex); |
1961 | |
1962 | FillJemallocPtrInfo(aPtr, index, aInfo); |
1963 | #if DEBUG1 |
1964 | Log("JemallocPtrInfo(%p[%zu]) -> {%zu, %p, %zu, %zu}\n", aPtr, index, |
1965 | size_t(aInfo->tag), aInfo->addr, aInfo->size, aInfo->arenaId); |
1966 | #else |
1967 | Log("JemallocPtrInfo(%p[%zu]) -> {%zu, %p, %zu}\n", aPtr, index, |
1968 | size_t(aInfo->tag), aInfo->addr, aInfo->size); |
1969 | #endif |
1970 | } |
1971 | |
1972 | inline void* MozJemallocPHC::moz_arena_malloc(arena_id_t aArenaId, |
1973 | size_t aReqSize) { |
1974 | return PageMalloc(Some(aArenaId), aReqSize); |
1975 | } |
1976 | |
1977 | inline void* MozJemallocPHC::moz_arena_calloc(arena_id_t aArenaId, size_t aNum, |
1978 | size_t aReqSize) { |
1979 | return PageCalloc(Some(aArenaId), aNum, aReqSize); |
1980 | } |
1981 | |
1982 | inline void* MozJemallocPHC::moz_arena_realloc(arena_id_t aArenaId, |
1983 | void* aOldPtr, size_t aNewSize) { |
1984 | return PageRealloc(Some(aArenaId), aOldPtr, aNewSize); |
1985 | } |
1986 | |
1987 | inline void MozJemallocPHC::moz_arena_free(arena_id_t aArenaId, void* aPtr) { |
1988 | return PageFree(Some(aArenaId), aPtr); |
1989 | } |
1990 | |
1991 | inline void* MozJemallocPHC::moz_arena_memalign(arena_id_t aArenaId, |
1992 | size_t aAlignment, |
1993 | size_t aReqSize) { |
1994 | return PageMemalign(Some(aArenaId), aAlignment, aReqSize); |
1995 | } |
1996 | |
1997 | bool PHC::IsPHCAllocation(const void* aPtr, mozilla::phc::AddrInfo* aOut) { |
1998 | PtrKind pk = sRegion.PtrKind(aPtr); |
1999 | MOZ_ASSERT(!pk.IsNothing())do { static_assert( mozilla::detail::AssertionConditionType< decltype(!pk.IsNothing())>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(!pk.IsNothing()))), 0))) { do { } while (false); MOZ_ReportAssertionFailure("!pk.IsNothing()" , "/root/firefox-clang/memory/build/PHC.cpp", 1999); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "!pk.IsNothing()" ")"); do { MOZ_CrashSequence (__null, 1999); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
2000 | |
2001 | bool isGuardPage = false; |
2002 | if (pk.IsGuardPage()) { |
2003 | if ((uintptr_t(aPtr) % kPageSize) < (kPageSize / 2)) { |
2004 | // The address is in the lower half of a guard page, so it's probably an |
2005 | // overflow. But first check that it is not on the very first guard |
2006 | // page, in which case it cannot be an overflow, and we ignore it. |
2007 | if (sRegion.IsInFirstGuardPage(aPtr)) { |
2008 | return false; |
2009 | } |
2010 | |
2011 | // Get the allocation page preceding this guard page. |
2012 | pk = sRegion.PtrKind(static_cast<const uint8_t*>(aPtr) - kPageSize); |
2013 | |
2014 | } else { |
2015 | // The address is in the upper half of a guard page, so it's probably an |
2016 | // underflow. Get the allocation page following this guard page. |
2017 | pk = sRegion.PtrKind(static_cast<const uint8_t*>(aPtr) + kPageSize); |
2018 | } |
2019 | |
2020 | // Make a note of the fact that we hit a guard page. |
2021 | isGuardPage = true; |
2022 | } |
2023 | |
2024 | // At this point we know we have an allocation page. |
2025 | uintptr_t index = pk.AllocPageIndex(); |
2026 | |
2027 | if (aOut) { |
2028 | if (mMutex.TryLock()) { |
2029 | FillAddrInfo(index, aPtr, isGuardPage, *aOut); |
2030 | Log("IsPHCAllocation: %zu, %p, %zu, %zu, %zu\n", size_t(aOut->mKind), |
2031 | aOut->mBaseAddr, aOut->mUsableSize, |
2032 | aOut->mAllocStack.isSome() ? aOut->mAllocStack->mLength : 0, |
2033 | aOut->mFreeStack.isSome() ? aOut->mFreeStack->mLength : 0); |
2034 | mMutex.Unlock(); |
2035 | } else { |
2036 | Log("IsPHCAllocation: PHC is locked\n"); |
2037 | aOut->mPhcWasLocked = true; |
2038 | } |
2039 | } |
2040 | return true; |
2041 | } |
2042 | |
2043 | namespace mozilla::phc { |
2044 | |
2045 | bool IsPHCAllocation(const void* aPtr, AddrInfo* aOut) { |
2046 | if (!FastIsPHCPtr(aPtr)) { |
2047 | return false; |
2048 | } |
2049 | |
2050 | return PHC::sPHC->IsPHCAllocation(aPtr, aOut); |
2051 | } |
2052 | |
2053 | void DisablePHCOnCurrentThread() { |
2054 | PHC::DisableOnCurrentThread(); |
2055 | Log("DisablePHCOnCurrentThread: %zu\n", 0ul); |
2056 | } |
2057 | |
2058 | void ReenablePHCOnCurrentThread() { |
2059 | PHC::sPHC->EnableOnCurrentThread(); |
2060 | Log("ReenablePHCOnCurrentThread: %zu\n", 0ul); |
2061 | } |
2062 | |
2063 | bool IsPHCEnabledOnCurrentThread() { |
2064 | bool enabled = !PHC::IsDisabledOnCurrentThread(); |
2065 | Log("IsPHCEnabledOnCurrentThread: %zu\n", size_t(enabled)); |
2066 | return enabled; |
2067 | } |
2068 | |
2069 | void PHCMemoryUsage(MemoryUsage& aMemoryUsage) { |
2070 | if (!maybe_init()) { |
2071 | aMemoryUsage = MemoryUsage(); |
2072 | return; |
2073 | } |
2074 | |
2075 | aMemoryUsage.mMetadataBytes = metadata_size(); |
2076 | if (PHC::sPHC) { |
2077 | aMemoryUsage.mFragmentationBytes = PHC::sPHC->FragmentationBytes(); |
2078 | } else { |
2079 | aMemoryUsage.mFragmentationBytes = 0; |
2080 | } |
2081 | } |
2082 | |
2083 | void GetPHCStats(PHCStats& aStats) { |
2084 | if (!maybe_init()) { |
2085 | aStats = PHCStats(); |
2086 | return; |
2087 | } |
2088 | |
2089 | aStats = PHC::sPHC->GetPageStats(); |
2090 | } |
2091 | |
2092 | // Enable or Disable PHC at runtime. If PHC is disabled it will still trap |
2093 | // bad uses of previous allocations, but won't track any new allocations. |
2094 | void SetPHCState(PHCState aState) { |
2095 | if (!maybe_init()) { |
2096 | return; |
2097 | } |
2098 | |
2099 | PHC::sPHC->SetState(aState); |
2100 | } |
2101 | |
2102 | void SetPHCProbabilities(int64_t aAvgDelayFirst, int64_t aAvgDelayNormal, |
2103 | int64_t aAvgDelayPageReuse) { |
2104 | if (!maybe_init()) { |
2105 | return; |
2106 | } |
2107 | |
2108 | PHC::sPHC->SetProbabilities(aAvgDelayFirst, aAvgDelayNormal, |
2109 | aAvgDelayPageReuse); |
2110 | } |
2111 | |
2112 | } // namespace mozilla::phc |
2113 | |
2114 | #if PHC_LOGGING0 |
2115 | static size_t GetPid() { return size_t(getpid()); } |
2116 | |
2117 | static size_t GetTid() { |
2118 | # if defined(XP_WIN) |
2119 | return size_t(GetCurrentThreadId()); |
2120 | # else |
2121 | return size_t(pthread_self()); |
2122 | # endif |
2123 | } |
2124 | #endif // PHC_LOGGING |
2125 | |
2126 | static void Log(const char* fmt, ...) { |
2127 | #if PHC_LOGGING0 |
2128 | # if defined(XP_WIN) |
2129 | # define LOG_STDERR \ |
2130 | reinterpret_cast<intptr_t>(GetStdHandle(STD_ERROR_HANDLE)) |
2131 | # else |
2132 | # define LOG_STDERR 2 |
2133 | # endif |
2134 | |
2135 | char buf[256]; |
2136 | size_t pos = SNPrintf(buf, sizeof(buf), "PHC[%zu,%zu,~%zu] ", GetPid(), |
2137 | GetTid(), size_t(PHC::Now())); |
2138 | va_list vargs; |
2139 | va_start(vargs, fmt)__builtin_va_start(vargs, fmt); |
2140 | pos += VSNPrintf(&buf[pos], sizeof(buf) - pos, fmt, vargs); |
2141 | MOZ_ASSERT(pos < sizeof(buf))do { static_assert( mozilla::detail::AssertionConditionType< decltype(pos < sizeof(buf))>::isValid, "invalid assertion condition" ); if ((__builtin_expect(!!(!(!!(pos < sizeof(buf)))), 0)) ) { do { } while (false); MOZ_ReportAssertionFailure("pos < sizeof(buf)" , "/root/firefox-clang/memory/build/PHC.cpp", 2141); AnnotateMozCrashReason ("MOZ_ASSERT" "(" "pos < sizeof(buf)" ")"); do { MOZ_CrashSequence (__null, 2141); __attribute__((nomerge)) ::abort(); } while ( false); } } while (false); |
2142 | va_end(vargs)__builtin_va_end(vargs); |
2143 | |
2144 | FdPuts(LOG_STDERR, buf, pos); |
2145 | #endif // PHC_LOGGING |
2146 | } |