1 // Copyright 2018 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/base/bounded-page-allocator.h"
6
7 namespace v8 {
8 namespace base {
9
BoundedPageAllocator(v8::PageAllocator * page_allocator,Address start,size_t size,size_t allocate_page_size,PageInitializationMode page_initialization_mode)10 BoundedPageAllocator::BoundedPageAllocator(
11 v8::PageAllocator* page_allocator, Address start, size_t size,
12 size_t allocate_page_size, PageInitializationMode page_initialization_mode)
13 : allocate_page_size_(allocate_page_size),
14 commit_page_size_(page_allocator->CommitPageSize()),
15 page_allocator_(page_allocator),
16 region_allocator_(start, size, allocate_page_size_),
17 page_initialization_mode_(page_initialization_mode) {
18 DCHECK_NOT_NULL(page_allocator);
19 DCHECK(IsAligned(allocate_page_size, page_allocator->AllocatePageSize()));
20 DCHECK(IsAligned(allocate_page_size_, commit_page_size_));
21 }
22
begin() const23 BoundedPageAllocator::Address BoundedPageAllocator::begin() const {
24 return region_allocator_.begin();
25 }
26
size() const27 size_t BoundedPageAllocator::size() const { return region_allocator_.size(); }
28
AllocatePages(void * hint,size_t size,size_t alignment,PageAllocator::Permission access)29 void* BoundedPageAllocator::AllocatePages(void* hint, size_t size,
30 size_t alignment,
31 PageAllocator::Permission access) {
32 MutexGuard guard(&mutex_);
33 DCHECK(IsAligned(alignment, region_allocator_.page_size()));
34 DCHECK(IsAligned(alignment, allocate_page_size_));
35
36 Address address = RegionAllocator::kAllocationFailure;
37
38 Address hint_address = reinterpret_cast<Address>(hint);
39 if (hint_address && IsAligned(hint_address, alignment) &&
40 region_allocator_.contains(hint_address, size)) {
41 if (region_allocator_.AllocateRegionAt(hint_address, size)) {
42 address = hint_address;
43 }
44 }
45
46 if (address == RegionAllocator::kAllocationFailure) {
47 if (alignment <= allocate_page_size_) {
48 // TODO(ishell): Consider using randomized version here.
49 address = region_allocator_.AllocateRegion(size);
50 } else {
51 address = region_allocator_.AllocateAlignedRegion(size, alignment);
52 }
53 }
54
55 if (address == RegionAllocator::kAllocationFailure) {
56 return nullptr;
57 }
58
59 void* ptr = reinterpret_cast<void*>(address);
60 if (!page_allocator_->SetPermissions(ptr, size, access)) {
61 // This most likely means that we ran out of memory.
62 CHECK_EQ(region_allocator_.FreeRegion(address), size);
63 return nullptr;
64 }
65
66 return ptr;
67 }
68
AllocatePagesAt(Address address,size_t size,PageAllocator::Permission access)69 bool BoundedPageAllocator::AllocatePagesAt(Address address, size_t size,
70 PageAllocator::Permission access) {
71 DCHECK(IsAligned(address, allocate_page_size_));
72 DCHECK(IsAligned(size, allocate_page_size_));
73
74 {
75 MutexGuard guard(&mutex_);
76 DCHECK(region_allocator_.contains(address, size));
77
78 if (!region_allocator_.AllocateRegionAt(address, size)) {
79 return false;
80 }
81 }
82
83 void* ptr = reinterpret_cast<void*>(address);
84 if (!page_allocator_->SetPermissions(ptr, size, access)) {
85 // This most likely means that we ran out of memory.
86 CHECK_EQ(region_allocator_.FreeRegion(address), size);
87 return false;
88 }
89
90 return true;
91 }
92
ReserveForSharedMemoryMapping(void * ptr,size_t size)93 bool BoundedPageAllocator::ReserveForSharedMemoryMapping(void* ptr,
94 size_t size) {
95 Address address = reinterpret_cast<Address>(ptr);
96 DCHECK(IsAligned(address, allocate_page_size_));
97 DCHECK(IsAligned(size, commit_page_size_));
98
99 {
100 MutexGuard guard(&mutex_);
101 DCHECK(region_allocator_.contains(address, size));
102
103 // Region allocator requires page size rather than commit size so just over-
104 // allocate there since any extra space couldn't be used anyway.
105 size_t region_size = RoundUp(size, allocate_page_size_);
106 if (!region_allocator_.AllocateRegionAt(
107 address, region_size, RegionAllocator::RegionState::kExcluded)) {
108 return false;
109 }
110 }
111
112 CHECK(page_allocator_->SetPermissions(ptr, size,
113 PageAllocator::Permission::kNoAccess));
114 return true;
115 }
116
FreePages(void * raw_address,size_t size)117 bool BoundedPageAllocator::FreePages(void* raw_address, size_t size) {
118 MutexGuard guard(&mutex_);
119
120 Address address = reinterpret_cast<Address>(raw_address);
121 CHECK_EQ(size, region_allocator_.FreeRegion(address));
122 if (page_initialization_mode_ ==
123 PageInitializationMode::kAllocatedPagesMustBeZeroInitialized) {
124 // When we are required to return zero-initialized pages, we decommit the
125 // pages here, which will cause any wired pages to be removed by the OS.
126 CHECK(page_allocator_->DecommitPages(raw_address, size));
127 } else {
128 DCHECK_EQ(page_initialization_mode_,
129 PageInitializationMode::kAllocatedPagesCanBeUninitialized);
130 CHECK(page_allocator_->SetPermissions(raw_address, size,
131 PageAllocator::kNoAccess));
132 }
133 return true;
134 }
135
ReleasePages(void * raw_address,size_t size,size_t new_size)136 bool BoundedPageAllocator::ReleasePages(void* raw_address, size_t size,
137 size_t new_size) {
138 Address address = reinterpret_cast<Address>(raw_address);
139 DCHECK(IsAligned(address, allocate_page_size_));
140
141 DCHECK_LT(new_size, size);
142 DCHECK(IsAligned(size - new_size, commit_page_size_));
143
144 // This must be held until the page permissions are updated.
145 MutexGuard guard(&mutex_);
146
147 // Check if we freed any allocatable pages by this release.
148 size_t allocated_size = RoundUp(size, allocate_page_size_);
149 size_t new_allocated_size = RoundUp(new_size, allocate_page_size_);
150
151 #ifdef DEBUG
152 {
153 // There must be an allocated region at given |address| of a size not
154 // smaller than |size|.
155 DCHECK_EQ(allocated_size, region_allocator_.CheckRegion(address));
156 }
157 #endif
158
159 if (new_allocated_size < allocated_size) {
160 region_allocator_.TrimRegion(address, new_allocated_size);
161 }
162
163 // Keep the region in "used" state just uncommit some pages.
164 Address free_address = address + new_size;
165 size_t free_size = size - new_size;
166 if (page_initialization_mode_ ==
167 PageInitializationMode::kAllocatedPagesMustBeZeroInitialized) {
168 // See comment in FreePages().
169 CHECK(page_allocator_->DecommitPages(reinterpret_cast<void*>(free_address),
170 free_size));
171 } else {
172 DCHECK_EQ(page_initialization_mode_,
173 PageInitializationMode::kAllocatedPagesCanBeUninitialized);
174 CHECK(page_allocator_->SetPermissions(reinterpret_cast<void*>(free_address),
175 free_size, PageAllocator::kNoAccess));
176 }
177 return true;
178 }
179
SetPermissions(void * address,size_t size,PageAllocator::Permission access)180 bool BoundedPageAllocator::SetPermissions(void* address, size_t size,
181 PageAllocator::Permission access) {
182 DCHECK(IsAligned(reinterpret_cast<Address>(address), commit_page_size_));
183 DCHECK(IsAligned(size, commit_page_size_));
184 DCHECK(region_allocator_.contains(reinterpret_cast<Address>(address), size));
185 return page_allocator_->SetPermissions(address, size, access);
186 }
187
DiscardSystemPages(void * address,size_t size)188 bool BoundedPageAllocator::DiscardSystemPages(void* address, size_t size) {
189 return page_allocator_->DiscardSystemPages(address, size);
190 }
191
DecommitPages(void * address,size_t size)192 bool BoundedPageAllocator::DecommitPages(void* address, size_t size) {
193 return page_allocator_->DecommitPages(address, size);
194 }
195
196 } // namespace base
197 } // namespace v8
198