1 // Copyright 2016 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "src/zone/accounting-allocator.h"
6
7 #include <memory>
8
9 #include "src/base/bounded-page-allocator.h"
10 #include "src/base/logging.h"
11 #include "src/base/macros.h"
12 #include "src/utils/allocation.h"
13 #include "src/zone/zone-compression.h"
14 #include "src/zone/zone-segment.h"
15
16 namespace v8 {
17 namespace internal {
18
19 // These definitions are here in order to please the linker, which in debug mode
20 // sometimes requires static constants to be defined in .cc files.
21 const size_t ZoneCompression::kReservationSize;
22 const size_t ZoneCompression::kReservationAlignment;
23
24 namespace {
25
26 static constexpr size_t kZonePageSize = 256 * KB;
27
ReserveAddressSpace(v8::PageAllocator * platform_allocator)28 VirtualMemory ReserveAddressSpace(v8::PageAllocator* platform_allocator) {
29 DCHECK(IsAligned(ZoneCompression::kReservationSize,
30 platform_allocator->AllocatePageSize()));
31
32 void* hint = reinterpret_cast<void*>(RoundDown(
33 reinterpret_cast<uintptr_t>(platform_allocator->GetRandomMmapAddr()),
34 ZoneCompression::kReservationAlignment));
35
36 VirtualMemory memory(platform_allocator, ZoneCompression::kReservationSize,
37 hint, ZoneCompression::kReservationAlignment);
38 if (memory.IsReserved()) {
39 CHECK(IsAligned(memory.address(), ZoneCompression::kReservationAlignment));
40 return memory;
41 }
42
43 FATAL(
44 "Fatal process out of memory: Failed to reserve memory for compressed "
45 "zones");
46 UNREACHABLE();
47 }
48
CreateBoundedAllocator(v8::PageAllocator * platform_allocator,Address reservation_start)49 std::unique_ptr<v8::base::BoundedPageAllocator> CreateBoundedAllocator(
50 v8::PageAllocator* platform_allocator, Address reservation_start) {
51 CHECK(reservation_start);
52 CHECK(IsAligned(reservation_start, ZoneCompression::kReservationAlignment));
53
54 auto allocator = std::make_unique<v8::base::BoundedPageAllocator>(
55 platform_allocator, reservation_start, ZoneCompression::kReservationSize,
56 kZonePageSize);
57
58 // Exclude first page from allocation to ensure that accesses through
59 // decompressed null pointer will seg-fault.
60 allocator->AllocatePagesAt(reservation_start, kZonePageSize,
61 v8::PageAllocator::kNoAccess);
62 return allocator;
63 }
64
65 } // namespace
66
AccountingAllocator()67 AccountingAllocator::AccountingAllocator() {
68 if (COMPRESS_ZONES_BOOL) {
69 v8::PageAllocator* platform_page_allocator = GetPlatformPageAllocator();
70 VirtualMemory memory = ReserveAddressSpace(platform_page_allocator);
71 reserved_area_ = std::make_unique<VirtualMemory>(std::move(memory));
72 bounded_page_allocator_ = CreateBoundedAllocator(platform_page_allocator,
73 reserved_area_->address());
74 }
75 }
76
77 AccountingAllocator::~AccountingAllocator() = default;
78
AllocateSegment(size_t bytes,bool supports_compression)79 Segment* AccountingAllocator::AllocateSegment(size_t bytes,
80 bool supports_compression) {
81 void* memory;
82 if (COMPRESS_ZONES_BOOL && supports_compression) {
83 bytes = RoundUp(bytes, kZonePageSize);
84 memory = AllocatePages(bounded_page_allocator_.get(), nullptr, bytes,
85 kZonePageSize, PageAllocator::kReadWrite);
86
87 } else {
88 memory = AllocWithRetry(bytes);
89 }
90 if (memory == nullptr) return nullptr;
91
92 size_t current =
93 current_memory_usage_.fetch_add(bytes, std::memory_order_relaxed) + bytes;
94 size_t max = max_memory_usage_.load(std::memory_order_relaxed);
95 while (current > max && !max_memory_usage_.compare_exchange_weak(
96 max, current, std::memory_order_relaxed)) {
97 // {max} was updated by {compare_exchange_weak}; retry.
98 }
99 DCHECK_LE(sizeof(Segment), bytes);
100 return new (memory) Segment(bytes);
101 }
102
ReturnSegment(Segment * segment,bool supports_compression)103 void AccountingAllocator::ReturnSegment(Segment* segment,
104 bool supports_compression) {
105 segment->ZapContents();
106 size_t segment_size = segment->total_size();
107 current_memory_usage_.fetch_sub(segment_size, std::memory_order_relaxed);
108 segment->ZapHeader();
109 if (COMPRESS_ZONES_BOOL && supports_compression) {
110 CHECK(FreePages(bounded_page_allocator_.get(), segment, segment_size));
111 } else {
112 free(segment);
113 }
114 }
115
116 } // namespace internal
117 } // namespace v8
118