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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/renderer/performance_manager/mechanisms/userspace_swap_impl_chromeos.h"
#include <signal.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <vector>
#include "base/threading/scoped_blocking_call.h"
#include "chromeos/ash/components/memory/userspace_swap/userspace_swap.h"
#include "chromeos/ash/components/memory/userspace_swap/userspace_swap.mojom.h"
#include "mojo/public/cpp/bindings/self_owned_receiver.h"
// MREMAP_DONTUNMAP was added in the 5.7 kernel, but we've backported it to
// earlier CrOS kernels.
#if !defined(MREMAP_DONTUNMAP)
#define MREMAP_DONTUNMAP 4
#endif
namespace performance_manager {
namespace mechanism {
using ::ash::memory::userspace_swap::UserspaceSwapConfig;
UserspaceSwapImpl::UserspaceSwapImpl() {
CHECK(UserspaceSwapImpl::PlatformSupportsUserspaceSwap());
}
UserspaceSwapImpl::~UserspaceSwapImpl() = default;
// static
void UserspaceSwapImpl::Create(
mojo::PendingReceiver<::userspace_swap::mojom::UserspaceSwap> receiver) {
if (!PlatformSupportsUserspaceSwap()) {
DLOG(WARNING) << "Userspace swap not supported by platform";
return;
}
auto impl = std::make_unique<UserspaceSwapImpl>();
mojo::MakeSelfOwnedReceiver(std::move(impl), std::move(receiver));
}
// static
bool UserspaceSwapImpl::PlatformSupportsUserspaceSwap() {
return ash::memory::userspace_swap::UserspaceSwapSupportedAndEnabled();
}
void UserspaceSwapImpl::MovePTEsLeavingMapping(MemoryRegionPtr src,
uint64_t dest) {
DCHECK(PlatformSupportsUserspaceSwap());
// We're moving to a known location, the location provided to us here is one
// that the renderer created and reserved for the browser the renderers
// address space for moving mappings to. The browser will observe this remap
// and then it will know it can safely use process_vm_readv() to move over the
// memory.
//
// The MREMAP_DONTUNMAP (which requires MREMAP_MAYMOVE) is used to move just
// the PTEs leaving the original mapping in place (with the userfaultfd still
// attached). The MREMAP_FIXED tells the kernel we know where we want the
// memory to go.
void* dest_mapping =
mremap(reinterpret_cast<void*>(src->address), src->length, src->length,
MREMAP_MAYMOVE | MREMAP_DONTUNMAP | MREMAP_FIXED,
reinterpret_cast<void*>(dest));
PCHECK(dest_mapping != MAP_FAILED) << "mremap failed";
}
void UserspaceSwapImpl::MapArea(MemoryRegionPtr area) {
DCHECK(PlatformSupportsUserspaceSwap());
// MapArea is used to drop pages after they have been read over to the browser
// process. We do this rather than MADV_DONTNEED because this will fully drop
// the VMA and recreate it while holding the MM sem. This means the memory
// will be unaccounted.
void* dest_mapping =
mmap(reinterpret_cast<void*>(area->address), area->length, PROT_NONE,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
PCHECK(dest_mapping != MAP_FAILED) << "Unable to map area";
}
void UserspaceSwapImpl::GetPartitionAllocSuperPagesUsed(
int32_t max_superpages,
UserspaceSwapImpl::GetPartitionAllocSuperPagesUsedCallback callback) {
std::vector<::userspace_swap::mojom::MemoryRegionPtr> areas;
ash::memory::userspace_swap::GetPartitionAllocSuperPagesInUse(max_superpages,
areas);
std::move(callback).Run(std::move(areas));
}
} // namespace mechanism
} // namespace performance_manager
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