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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/base/bounded-page-allocator.h"
namespace v8 {
namespace base {
BoundedPageAllocator::BoundedPageAllocator(v8::PageAllocator* page_allocator,
Address start, size_t size,
size_t allocate_page_size)
: allocate_page_size_(allocate_page_size),
commit_page_size_(page_allocator->CommitPageSize()),
page_allocator_(page_allocator),
region_allocator_(start, size, allocate_page_size_) {
CHECK_NOT_NULL(page_allocator);
CHECK(IsAligned(allocate_page_size, page_allocator->AllocatePageSize()));
CHECK(IsAligned(allocate_page_size_, commit_page_size_));
}
BoundedPageAllocator::Address BoundedPageAllocator::begin() const {
return region_allocator_.begin();
}
size_t BoundedPageAllocator::size() const { return region_allocator_.size(); }
void* BoundedPageAllocator::AllocatePages(void* hint, size_t size,
size_t alignment,
PageAllocator::Permission access) {
MutexGuard guard(&mutex_);
CHECK(IsAligned(alignment, region_allocator_.page_size()));
// Region allocator does not support alignments bigger than it's own
// allocation alignment.
CHECK_LE(alignment, allocate_page_size_);
// TODO(ishell): Consider using randomized version here.
Address address = region_allocator_.AllocateRegion(size);
if (address == RegionAllocator::kAllocationFailure) {
return nullptr;
}
CHECK(page_allocator_->SetPermissions(reinterpret_cast<void*>(address), size,
access));
return reinterpret_cast<void*>(address);
}
bool BoundedPageAllocator::AllocatePagesAt(Address address, size_t size,
PageAllocator::Permission access) {
CHECK(IsAligned(address, allocate_page_size_));
CHECK(IsAligned(size, allocate_page_size_));
CHECK(region_allocator_.contains(address, size));
if (!region_allocator_.AllocateRegionAt(address, size)) {
return false;
}
CHECK(page_allocator_->SetPermissions(reinterpret_cast<void*>(address), size,
access));
return true;
}
bool BoundedPageAllocator::FreePages(void* raw_address, size_t size) {
MutexGuard guard(&mutex_);
Address address = reinterpret_cast<Address>(raw_address);
size_t freed_size = region_allocator_.FreeRegion(address);
if (freed_size != size) return false;
CHECK(page_allocator_->SetPermissions(raw_address, size,
PageAllocator::kNoAccess));
return true;
}
bool BoundedPageAllocator::ReleasePages(void* raw_address, size_t size,
size_t new_size) {
Address address = reinterpret_cast<Address>(raw_address);
CHECK(IsAligned(address, allocate_page_size_));
DCHECK_LT(new_size, size);
DCHECK(IsAligned(size - new_size, commit_page_size_));
// Check if we freed any allocatable pages by this release.
size_t allocated_size = RoundUp(size, allocate_page_size_);
size_t new_allocated_size = RoundUp(new_size, allocate_page_size_);
#ifdef DEBUG
{
// There must be an allocated region at given |address| of a size not
// smaller than |size|.
MutexGuard guard(&mutex_);
CHECK_EQ(allocated_size, region_allocator_.CheckRegion(address));
}
#endif
if (new_allocated_size < allocated_size) {
MutexGuard guard(&mutex_);
region_allocator_.TrimRegion(address, new_allocated_size);
}
// Keep the region in "used" state just uncommit some pages.
Address free_address = address + new_size;
size_t free_size = size - new_size;
return page_allocator_->SetPermissions(reinterpret_cast<void*>(free_address),
free_size, PageAllocator::kNoAccess);
}
bool BoundedPageAllocator::SetPermissions(void* address, size_t size,
PageAllocator::Permission access) {
DCHECK(IsAligned(reinterpret_cast<Address>(address), commit_page_size_));
DCHECK(IsAligned(size, commit_page_size_));
DCHECK(region_allocator_.contains(reinterpret_cast<Address>(address), size));
return page_allocator_->SetPermissions(address, size, access);
}
bool BoundedPageAllocator::DiscardSystemPages(void* address, size_t size) {
return page_allocator_->DiscardSystemPages(address, size);
}
} // namespace base
} // namespace v8
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