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// Copyright 2020 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/heap/cppgc/page-memory.h"
#include "src/base/macros.h"
#include "src/heap/cppgc/sanitizers.h"
namespace cppgc {
namespace internal {
namespace {
void Unprotect(PageAllocator* allocator, const PageMemory& page_memory) {
if (SupportsCommittingGuardPages(allocator)) {
CHECK(allocator->SetPermissions(page_memory.writeable_region().base(),
page_memory.writeable_region().size(),
PageAllocator::Permission::kReadWrite));
} else {
// No protection in case the allocator cannot commit at the required
// granularity. Only protect if the allocator supports committing at that
// granularity.
//
// The allocator needs to support committing the overall range.
CHECK_EQ(0u,
page_memory.overall_region().size() % allocator->CommitPageSize());
CHECK(allocator->SetPermissions(page_memory.overall_region().base(),
page_memory.overall_region().size(),
PageAllocator::Permission::kReadWrite));
}
}
void Protect(PageAllocator* allocator, const PageMemory& page_memory) {
if (SupportsCommittingGuardPages(allocator)) {
// Swap the same region, providing the OS with a chance for fast lookup and
// change.
CHECK(allocator->SetPermissions(page_memory.writeable_region().base(),
page_memory.writeable_region().size(),
PageAllocator::Permission::kNoAccess));
} else {
// See Unprotect().
CHECK_EQ(0u,
page_memory.overall_region().size() % allocator->CommitPageSize());
CHECK(allocator->SetPermissions(page_memory.overall_region().base(),
page_memory.overall_region().size(),
PageAllocator::Permission::kNoAccess));
}
}
MemoryRegion ReserveMemoryRegion(PageAllocator* allocator,
size_t allocation_size) {
void* region_memory =
allocator->AllocatePages(nullptr, allocation_size, kPageSize,
PageAllocator::Permission::kNoAccess);
const MemoryRegion reserved_region(static_cast<Address>(region_memory),
allocation_size);
DCHECK_EQ(reserved_region.base() + allocation_size, reserved_region.end());
return reserved_region;
}
void FreeMemoryRegion(PageAllocator* allocator,
const MemoryRegion& reserved_region) {
// Make sure pages returned to OS are unpoisoned.
ASAN_UNPOISON_MEMORY_REGION(reserved_region.base(), reserved_region.size());
allocator->FreePages(reserved_region.base(), reserved_region.size());
}
} // namespace
PageMemoryRegion::PageMemoryRegion(PageAllocator* allocator,
MemoryRegion reserved_region, bool is_large)
: allocator_(allocator),
reserved_region_(reserved_region),
is_large_(is_large) {}
PageMemoryRegion::~PageMemoryRegion() {
FreeMemoryRegion(allocator_, reserved_region());
}
// static
constexpr size_t NormalPageMemoryRegion::kNumPageRegions;
NormalPageMemoryRegion::NormalPageMemoryRegion(PageAllocator* allocator)
: PageMemoryRegion(allocator,
ReserveMemoryRegion(
allocator, RoundUp(kPageSize * kNumPageRegions,
allocator->AllocatePageSize())),
false) {
#ifdef DEBUG
for (size_t i = 0; i < kNumPageRegions; ++i) {
DCHECK_EQ(false, page_memories_in_use_[i]);
}
#endif // DEBUG
}
NormalPageMemoryRegion::~NormalPageMemoryRegion() = default;
void NormalPageMemoryRegion::Allocate(Address writeable_base) {
const size_t index = GetIndex(writeable_base);
ChangeUsed(index, true);
Unprotect(allocator_, GetPageMemory(index));
}
void NormalPageMemoryRegion::Free(Address writeable_base) {
const size_t index = GetIndex(writeable_base);
ChangeUsed(index, false);
Protect(allocator_, GetPageMemory(index));
}
void NormalPageMemoryRegion::UnprotectForTesting() {
for (size_t i = 0; i < kNumPageRegions; ++i) {
Unprotect(allocator_, GetPageMemory(i));
}
}
LargePageMemoryRegion::LargePageMemoryRegion(PageAllocator* allocator,
size_t length)
: PageMemoryRegion(allocator,
ReserveMemoryRegion(
allocator, RoundUp(length + 2 * kGuardPageSize,
allocator->AllocatePageSize())),
true) {}
LargePageMemoryRegion::~LargePageMemoryRegion() = default;
void LargePageMemoryRegion::UnprotectForTesting() {
Unprotect(allocator_, GetPageMemory());
}
PageMemoryRegionTree::PageMemoryRegionTree() = default;
PageMemoryRegionTree::~PageMemoryRegionTree() = default;
void PageMemoryRegionTree::Add(PageMemoryRegion* region) {
DCHECK(region);
auto result = set_.emplace(region->reserved_region().base(), region);
USE(result);
DCHECK(result.second);
}
void PageMemoryRegionTree::Remove(PageMemoryRegion* region) {
DCHECK(region);
auto size = set_.erase(region->reserved_region().base());
USE(size);
DCHECK_EQ(1u, size);
}
NormalPageMemoryPool::NormalPageMemoryPool() = default;
NormalPageMemoryPool::~NormalPageMemoryPool() = default;
void NormalPageMemoryPool::Add(size_t bucket, NormalPageMemoryRegion* pmr,
Address writeable_base) {
DCHECK_LT(bucket, kNumPoolBuckets);
pool_[bucket].push_back(std::make_pair(pmr, writeable_base));
}
std::pair<NormalPageMemoryRegion*, Address> NormalPageMemoryPool::Take(
size_t bucket) {
DCHECK_LT(bucket, kNumPoolBuckets);
if (pool_[bucket].empty()) return {nullptr, nullptr};
std::pair<NormalPageMemoryRegion*, Address> pair = pool_[bucket].back();
pool_[bucket].pop_back();
return pair;
}
PageBackend::PageBackend(PageAllocator* allocator) : allocator_(allocator) {}
PageBackend::~PageBackend() = default;
Address PageBackend::AllocateNormalPageMemory(size_t bucket) {
std::pair<NormalPageMemoryRegion*, Address> result = page_pool_.Take(bucket);
if (!result.first) {
auto pmr = std::make_unique<NormalPageMemoryRegion>(allocator_);
for (size_t i = 0; i < NormalPageMemoryRegion::kNumPageRegions; ++i) {
page_pool_.Add(bucket, pmr.get(),
pmr->GetPageMemory(i).writeable_region().base());
}
page_memory_region_tree_.Add(pmr.get());
normal_page_memory_regions_.push_back(std::move(pmr));
return AllocateNormalPageMemory(bucket);
}
result.first->Allocate(result.second);
return result.second;
}
void PageBackend::FreeNormalPageMemory(size_t bucket, Address writeable_base) {
auto* pmr = static_cast<NormalPageMemoryRegion*>(
page_memory_region_tree_.Lookup(writeable_base));
pmr->Free(writeable_base);
page_pool_.Add(bucket, pmr, writeable_base);
}
Address PageBackend::AllocateLargePageMemory(size_t size) {
auto pmr = std::make_unique<LargePageMemoryRegion>(allocator_, size);
const PageMemory pm = pmr->GetPageMemory();
Unprotect(allocator_, pm);
page_memory_region_tree_.Add(pmr.get());
large_page_memory_regions_.insert(std::make_pair(pmr.get(), std::move(pmr)));
return pm.writeable_region().base();
}
void PageBackend::FreeLargePageMemory(Address writeable_base) {
PageMemoryRegion* pmr = page_memory_region_tree_.Lookup(writeable_base);
page_memory_region_tree_.Remove(pmr);
auto size = large_page_memory_regions_.erase(pmr);
USE(size);
DCHECK_EQ(1u, size);
}
} // namespace internal
} // namespace cppgc
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