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https://github.com/RGBCube/serenity
synced 2025-07-25 19:37:35 +00:00
Kernel: Implement read functionality for MemoryDevice
So far we only had mmap(2) functionality on the /dev/mem device, but now we can also do read(2) on it. The test unit was updated to check we are doing it safely.
This commit is contained in:
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6feb07fe43
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ca254699ec
4 changed files with 81 additions and 18 deletions
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@ -10,6 +10,7 @@
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#include <Kernel/Devices/MemoryDevice.h>
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#include <Kernel/Devices/MemoryDevice.h>
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#include <Kernel/Firmware/BIOS.h>
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#include <Kernel/Firmware/BIOS.h>
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#include <Kernel/Memory/AnonymousVMObject.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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#include <Kernel/Sections.h>
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namespace Kernel {
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namespace Kernel {
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@ -31,9 +32,17 @@ UNMAP_AFTER_INIT MemoryDevice::~MemoryDevice()
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{
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{
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}
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}
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ErrorOr<size_t> MemoryDevice::read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t)
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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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{
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TODO();
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if (!MM.is_allowed_to_read_physical_memory_for_userspace(PhysicalAddress(offset), length)) {
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dbgln("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 = 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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}
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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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ErrorOr<Memory::Region*> MemoryDevice::mmap(Process& process, OpenFileDescription&, Memory::VirtualRange const& range, u64 offset, int prot, bool shared)
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@ -41,7 +50,7 @@ ErrorOr<Memory::Region*> MemoryDevice::mmap(Process& process, OpenFileDescriptio
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auto viewed_address = PhysicalAddress(offset);
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auto viewed_address = PhysicalAddress(offset);
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dbgln("MemoryDevice: Trying to mmap physical memory at {} for range of {} bytes", viewed_address, range.size());
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dbgln("MemoryDevice: Trying to mmap physical memory at {} for range of {} bytes", viewed_address, range.size());
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if (!MM.is_allowed_to_mmap_physical_memory_to_userspace(viewed_address, range)) {
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if (!MM.is_allowed_to_read_physical_memory_for_userspace(viewed_address, range.size())) {
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dbgln("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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dbgln("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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return EINVAL;
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}
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}
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@ -209,13 +209,13 @@ UNMAP_AFTER_INIT void MemoryManager::register_reserved_ranges()
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m_reserved_memory_ranges.append(ContiguousReservedMemoryRange { range.start, m_physical_memory_ranges.last().start.get() + m_physical_memory_ranges.last().length - range.start.get() });
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m_reserved_memory_ranges.append(ContiguousReservedMemoryRange { range.start, m_physical_memory_ranges.last().start.get() + m_physical_memory_ranges.last().length - range.start.get() });
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}
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}
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bool MemoryManager::is_allowed_to_mmap_physical_memory_to_userspace(PhysicalAddress start_address, VirtualRange const& range) const
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bool MemoryManager::is_allowed_to_read_physical_memory_for_userspace(PhysicalAddress start_address, size_t read_length) const
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{
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{
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// Note: Guard against overflow in case someone tries to mmap on the edge of
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// Note: Guard against overflow in case someone tries to mmap on the edge of
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// the RAM
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// the RAM
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if (start_address.offset_addition_would_overflow(range.size()))
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if (start_address.offset_addition_would_overflow(read_length))
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return false;
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return false;
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auto end_address = start_address.offset(range.size());
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auto end_address = start_address.offset(read_length);
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for (auto& current_range : m_reserved_memory_ranges) {
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for (auto& current_range : m_reserved_memory_ranges) {
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if (current_range.start > start_address)
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if (current_range.start > start_address)
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continue;
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continue;
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@ -230,7 +230,7 @@ public:
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PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
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PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
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Vector<UsedMemoryRange> const& used_memory_ranges() { return m_used_memory_ranges; }
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Vector<UsedMemoryRange> const& used_memory_ranges() { return m_used_memory_ranges; }
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bool is_allowed_to_mmap_physical_memory_to_userspace(PhysicalAddress, VirtualRange const&) const;
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bool is_allowed_to_read_physical_memory_for_userspace(PhysicalAddress, size_t read_length) const;
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PhysicalPageEntry& get_physical_page_entry(PhysicalAddress);
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PhysicalPageEntry& get_physical_page_entry(PhysicalAddress);
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PhysicalAddress get_physical_address(PhysicalPage const&);
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PhysicalAddress get_physical_address(PhysicalPage const&);
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@ -9,12 +9,16 @@
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#include <assert.h>
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#include <assert.h>
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#include <errno.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdlib.h>
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#include <string.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <unistd.h>
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static u8 read_buffer[0x100000];
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static ALWAYS_INLINE bool mem_chunk(int fd, u64 base, u64 length)
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static ALWAYS_INLINE bool mem_chunk(int fd, u64 base, u64 length)
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{
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{
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u64 mmoffset = base % sysconf(_SC_PAGESIZE);
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u64 mmoffset = base % sysconf(_SC_PAGESIZE);
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@ -22,30 +26,80 @@ static ALWAYS_INLINE bool mem_chunk(int fd, u64 base, u64 length)
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return mmp != MAP_FAILED;
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return mmp != MAP_FAILED;
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}
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}
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enum class ReadResult {
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SeekFailure,
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ReadFailure,
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ReadSuccess,
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};
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static ALWAYS_INLINE ReadResult read_chunk(int fd, u64 base, u64 length)
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{
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VERIFY(length <= sizeof(read_buffer));
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auto rs = lseek(fd, base, SEEK_SET);
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if (rs < 0) {
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fprintf(stderr, "Couldn't seek to offset %" PRIi64 " while verifying: %s\n", base, strerror(errno));
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return ReadResult::SeekFailure;
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}
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if (read(fd, read_buffer, length) < 0)
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return ReadResult::ReadFailure;
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return ReadResult::ReadSuccess;
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}
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TEST_CASE(test_memory_access_device_read)
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{
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int rc = geteuid();
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EXPECT_EQ(rc, 0);
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int fd = open("/dev/mem", O_RDONLY);
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EXPECT(fd >= 0);
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// FIXME: This is expected to work on QEMU machines (both 440FX and Q35),
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// however, it will be much nicer to have some sort of a node in the ProcFS
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// to expose physical memory ranges (e820 memory map).
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auto read_result = read_chunk(fd, 0x0, 0x100000);
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EXPECT_EQ(read_result, ReadResult::ReadFailure);
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read_result = read_chunk(fd, 0xe0000, 0x100000 - 0xe0000);
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EXPECT_EQ(read_result, ReadResult::ReadSuccess);
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read_result = read_chunk(fd, 0x100000, 0x200000 - 0x100000);
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EXPECT_EQ(read_result, ReadResult::ReadFailure);
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read_result = read_chunk(fd, 0xf0000, 70000);
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EXPECT_EQ(read_result, ReadResult::ReadFailure);
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read_result = read_chunk(fd, 0xfffc0000, 16384);
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EXPECT_EQ(read_result, ReadResult::ReadSuccess);
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read_result = read_chunk(fd, 0xfffc0000, 0x100000);
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EXPECT_EQ(read_result, ReadResult::ReadFailure);
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}
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TEST_CASE(test_memory_access_device_mmap)
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TEST_CASE(test_memory_access_device_mmap)
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{
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{
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int rc = geteuid();
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int rc = geteuid();
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EXPECT_EQ(rc, 0);
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EXPECT_EQ(rc, 0);
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int fd = open("/dev/mem", O_RDONLY);
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int fd = open("/dev/mem", O_RDONLY);
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EXPECT_EQ(fd < 0, false);
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EXPECT(fd >= 0);
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// FIXME: This is expected to work on QEMU machines (both 440FX and Q35),
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// FIXME: This is expected to work on QEMU machines (both 440FX and Q35),
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// however, it will be much nicer to have some sort of a node in the ProcFS
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// however, it will be much nicer to have some sort of a node in the ProcFS
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// to expose physical memory ranges (e820 memory map).
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// to expose physical memory ranges (e820 memory map).
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auto result = mem_chunk(fd, 0xe0000, 0x100000 - 0xe0000);
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auto mmap_result = mem_chunk(fd, 0xe0000, 0x100000 - 0xe0000);
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EXPECT_EQ(result, true);
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EXPECT_EQ(mmap_result, true);
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result = mem_chunk(fd, 0x100000, 0x200000 - 0x100000);
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mmap_result = mem_chunk(fd, 0x100000, 0x200000 - 0x100000);
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EXPECT_EQ(result, false);
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EXPECT_EQ(mmap_result, false);
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result = mem_chunk(fd, 0xf0000, 70000);
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mmap_result = mem_chunk(fd, 0xf0000, 70000);
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EXPECT_EQ(result, false);
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EXPECT_EQ(mmap_result, false);
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result = mem_chunk(fd, 0xfffc0000, 16384);
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mmap_result = mem_chunk(fd, 0xfffc0000, 16384);
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EXPECT_EQ(result, true);
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EXPECT_EQ(mmap_result, true);
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result = mem_chunk(fd, 0xfffc0000, 0x100000);
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mmap_result = mem_chunk(fd, 0xfffc0000, 0x100000);
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EXPECT_EQ(result, false);
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EXPECT_EQ(mmap_result, false);
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}
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}
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