9c6834698f
In a previous commit I moved everything into the new subdirectories in FileSystem/SysFS directory without trying to actually make changes in the code itself too much. Now it's time to split the code to make it more readable and understandable, hence this change occurs now.
75 lines
2.9 KiB
C++
75 lines
2.9 KiB
C++
/*
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* Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Memory.h>
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#include <AK/StdLibExtras.h>
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#include <Kernel/Devices/DeviceManagement.h>
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#include <Kernel/Devices/MemoryDevice.h>
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#include <Kernel/Memory/AnonymousVMObject.h>
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#include <Kernel/Memory/TypedMapping.h>
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#include <Kernel/Sections.h>
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namespace Kernel {
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UNMAP_AFTER_INIT NonnullRefPtr<MemoryDevice> MemoryDevice::must_create()
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{
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auto memory_device_or_error = DeviceManagement::try_create_device<MemoryDevice>();
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// FIXME: Find a way to propagate errors
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VERIFY(!memory_device_or_error.is_error());
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return memory_device_or_error.release_value();
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}
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UNMAP_AFTER_INIT MemoryDevice::MemoryDevice()
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: CharacterDevice(1, 1)
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{
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}
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UNMAP_AFTER_INIT MemoryDevice::~MemoryDevice() = default;
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ErrorOr<size_t> MemoryDevice::read(OpenFileDescription&, u64 offset, UserOrKernelBuffer& buffer, size_t length)
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{
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if (!MM.is_allowed_to_read_physical_memory_for_userspace(PhysicalAddress(offset), length)) {
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dbgln_if(MEMORY_DEVICE_DEBUG, "MemoryDevice: Trying to read physical memory at {} for range of {} bytes failed due to violation of access", PhysicalAddress(offset), length);
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return EINVAL;
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}
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auto mapping = TRY(Memory::map_typed<u8>(PhysicalAddress(offset), length));
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auto bytes = ReadonlyBytes { mapping.ptr(), length };
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TRY(buffer.write(bytes));
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return length;
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}
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ErrorOr<Memory::Region*> MemoryDevice::mmap(Process& process, OpenFileDescription&, Memory::VirtualRange const& range, u64 offset, int prot, bool shared)
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{
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auto viewed_address = PhysicalAddress(offset);
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// Note: This check happens to guard against possible memory leak.
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// For example, if we try to mmap physical memory from 0x1000 to 0x2000 and you
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// can actually mmap only from 0x1001, then we would fail as usual.
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// However, in such case if we mmap from 0x1002, we are technically not violating
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// any rules, besides the fact that we mapped an entire page with two bytes which we
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// were not supposed to see. To prevent that, if we use mmap(2) syscall, we should
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// always consider the start page to be aligned on PAGE_SIZE, or to be more precise
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// is to be set to the page base of that start address.
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VERIFY(viewed_address == viewed_address.page_base());
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if (!MM.is_allowed_to_read_physical_memory_for_userspace(viewed_address, range.size())) {
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dbgln_if(MEMORY_DEVICE_DEBUG, "MemoryDevice: Trying to mmap physical memory at {} for range of {} bytes failed due to violation of access", viewed_address, range.size());
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return EINVAL;
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}
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auto vmobject = TRY(Memory::AnonymousVMObject::try_create_for_physical_range(viewed_address, range.size()));
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return process.address_space().allocate_region_with_vmobject(
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range,
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move(vmobject),
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0,
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"Mapped Physical Memory",
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prot,
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shared);
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}
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}
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