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https://github.com/RGBCube/serenity
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Libraries: Add LibDeviceTree for manipulating OpenFirmware Device Trees
Starting with header validation and a dump() method that can be used to debug future parsing work.
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5 changed files with 214 additions and 0 deletions
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@ -12,6 +12,7 @@ add_subdirectory(LibCrypt)
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add_subdirectory(LibCrypto)
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add_subdirectory(LibDebug)
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add_subdirectory(LibDesktop)
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add_subdirectory(LibDeviceTree)
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add_subdirectory(LibDiff)
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add_subdirectory(LibDl)
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add_subdirectory(LibDSP)
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7
Userland/Libraries/LibDeviceTree/CMakeLists.txt
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7
Userland/Libraries/LibDeviceTree/CMakeLists.txt
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set(SOURCES
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Validation.cpp
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)
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serenity_lib(LibDeviceTree DeviceTree)
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target_link_libraries(LibDeviceTree LibC LibCore)
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41
Userland/Libraries/LibDeviceTree/FlattenedDeviceTree.h
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41
Userland/Libraries/LibDeviceTree/FlattenedDeviceTree.h
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/*
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* Copyright (c) 2021, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Endian.h>
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#include <AK/Types.h>
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namespace DeviceTree {
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html
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struct FlattenedDeviceTreeHeader {
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BigEndian<u32> magic; // 0xDOODFEED (BE)
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BigEndian<u32> totalsize; // Total size of entire blob including padding b/w and after fields
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BigEndian<u32> off_dt_struct; // Offset of StructureBlock from beginning of header
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#sect-fdt-structure-block
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BigEndian<u32> off_dt_strings; // Offset of StringsBlock from beginning of header
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#sect-fdt-strings-block
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BigEndian<u32> off_mem_rsvmap; // Offset of MemoryReservationBlock from beginning of header
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BigEndian<u32> version; // 0.3 spec defines version 17
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BigEndian<u32> last_comp_version; // 0.3 spec back-compatible with version 16, mandated to be 16
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BigEndian<u32> boot_cpuid_phys; // Physical ID given in `reg` property of CPU node of boot cpu
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BigEndian<u32> size_dt_strings; // Length in bytes of StringsBlock
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BigEndian<u32> size_dt_struct; // Length in bytes of StructureBlock
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};
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static_assert(sizeof(FlattenedDeviceTreeHeader) == 40, "FDT Header size must match specification");
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#format
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struct FlattenedDeviceTreeReserveEntry {
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BigEndian<u64> address;
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BigEndian<u64> size;
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bool operator==(FlattenedDeviceTreeReserveEntry const& other) const { return other.address == address && other.size == size; }
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bool operator!=(FlattenedDeviceTreeReserveEntry const& other) const { return !(operator==(other)); }
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};
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static_assert(sizeof(FlattenedDeviceTreeReserveEntry) == 16, "FDT Memory Reservation entry size must match specification");
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} // namespace DeviceTree
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143
Userland/Libraries/LibDeviceTree/Validation.cpp
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Userland/Libraries/LibDeviceTree/Validation.cpp
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/*
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* Copyright (c) 2021, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Endian.h>
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#include <AK/Format.h>
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#include <AK/String.h>
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#include <LibDeviceTree/Validation.h>
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namespace DeviceTree {
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bool validate_flattened_device_tree(FlattenedDeviceTreeHeader const& header, u8 const* blob_start, size_t blob_size, Verbose verbose)
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{
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if (header.magic != 0xD00DFEEDU) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header has invalid magic value 0x{:08x}. Are you sure it's a flattened device tree?", header.magic);
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return false;
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}
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if ((header.off_mem_rsvmap & ~0x7) != header.off_mem_rsvmap) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header's MemoryReservationBlock is not 8 byte aligned! Offset: 0x{:08x}", header.off_mem_rsvmap);
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return false;
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}
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if ((header.off_dt_struct & ~0x3) != header.off_dt_struct) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header's StructureBlock is not 4 byte aligned! Offset: 0x{:08x}", header.off_dt_struct);
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return false;
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}
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if (header.totalsize != blob_size) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header total size mismatch: {}, expected {}!", header.totalsize, blob_size);
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return false;
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}
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if (header.off_dt_struct > blob_size) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header reports larger StructureBlock offset than possible: {} but total size is {}!", header.off_dt_struct, blob_size);
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return false;
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}
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if (header.off_dt_strings > blob_size) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header reports larger StringsBlock offset than possible: {} but total size is {}!", header.off_dt_strings, blob_size);
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return false;
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}
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if (header.off_mem_rsvmap > blob_size) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header reports larger MemoryReservationBlock offset than possible: {} but total size is {}!", header.off_mem_rsvmap, blob_size);
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return false;
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}
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// Verify format is correct. Header --> MemoryReservation --> Structures --> Strings
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if (header.off_dt_strings <= header.off_dt_struct) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header has invalid StringsBlock offset {}, must be after v (@ {})", header.off_dt_strings, header.off_dt_struct);
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return false;
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}
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if (header.off_dt_struct <= header.off_mem_rsvmap) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header has invalid StructureBlock offset {}, must be after MemoryReservationBlock (@ {})", header.off_dt_struct, header.off_mem_rsvmap);
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return false;
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}
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if (header.version != 17) {
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if (verbose == Verbose::Yes)
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warnln("Expected FDT header version 17, got {}", header.version);
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return false;
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}
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if (header.last_comp_version != 16) {
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if (verbose == Verbose::Yes)
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warnln("Expected FDT header last compatible version 16, got {}", header.last_comp_version);
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return false;
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}
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auto* mem_reserve_block = reinterpret_cast<FlattenedDeviceTreeReserveEntry const*>(&blob_start[header.off_mem_rsvmap]);
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u64 next_block_offset = header.off_mem_rsvmap + sizeof(FlattenedDeviceTreeReserveEntry);
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while ((next_block_offset < header.off_dt_struct) && (*mem_reserve_block != FlattenedDeviceTreeReserveEntry {})) {
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++mem_reserve_block;
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next_block_offset += sizeof(FlattenedDeviceTreeReserveEntry);
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}
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if (next_block_offset >= header.off_dt_strings) {
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if (verbose == Verbose::Yes)
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warnln("FDT malformed, MemoryReservationBlock spill into StructureBlock section!");
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return false;
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}
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// check for overlap. Overflow not possible b/c the fields are u32
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u64 structure_block_size = header.off_dt_struct + header.size_dt_struct;
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if ((structure_block_size > header.off_dt_strings) || (structure_block_size > blob_size)) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header reports invalid StructureBlock block size: {} is too large given StringsBlock offset {} and total size {}", structure_block_size, header.off_dt_strings, blob_size);
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return false;
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}
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u64 strings_block_size = header.off_dt_strings + header.size_dt_strings;
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if (strings_block_size > blob_size) {
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if (verbose == Verbose::Yes)
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warnln("FDT Header reports invalid StringsBlock size: {} is too large given total size {}", structure_block_size, blob_size);
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return false;
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}
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return true;
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}
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bool dump(FlattenedDeviceTreeHeader const& header, u8 const* blob_start, size_t blob_size)
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{
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outln("/dts-v1/;");
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outln("// magic: 0x{:08x}", header.magic);
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outln("// totalsize: 0x{:08x} ({})", header.totalsize, header.totalsize);
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outln("// off_dt_struct: 0x{:08x}", header.off_dt_struct);
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outln("// off_dt_strings: 0x{:08x}", header.off_dt_strings);
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outln("// off_mem_rsvmap: 0x{:08x}", header.off_mem_rsvmap);
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outln("// version: 0x{:08x}", header.version);
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outln("// last_comp_version: 0x{:08x}", header.last_comp_version);
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outln("// boot_cpuid_phys: 0x{:08x}", header.boot_cpuid_phys);
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outln("// size_dt_strings: 0x{:08x}", header.size_dt_strings);
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outln("// size_dt_struct: 0x{:08x}", header.size_dt_struct);
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if (!validate_flattened_device_tree(header, blob_start, blob_size, Verbose::Yes))
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return false;
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// Now that we know the device tree is valid, print out the rest of the information
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auto* mem_reserve_block = reinterpret_cast<FlattenedDeviceTreeReserveEntry const*>(&blob_start[header.off_mem_rsvmap]);
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u64 next_block_offset = header.off_mem_rsvmap + sizeof(FlattenedDeviceTreeReserveEntry);
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while ((next_block_offset < header.off_dt_struct) && (*mem_reserve_block != FlattenedDeviceTreeReserveEntry {})) {
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outln("/memreserve/ 0x{:08x} 0x{:08x};", mem_reserve_block->address, mem_reserve_block->size);
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++mem_reserve_block;
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next_block_offset += sizeof(FlattenedDeviceTreeReserveEntry);
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}
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return true;
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}
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} // namespace DeviceTree
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22
Userland/Libraries/LibDeviceTree/Validation.h
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Userland/Libraries/LibDeviceTree/Validation.h
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/*
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* Copyright (c) 2021, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <LibDeviceTree/FlattenedDeviceTree.h>
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namespace DeviceTree {
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enum class Verbose {
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No,
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Yes
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};
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bool validate_flattened_device_tree(FlattenedDeviceTreeHeader const& header, u8 const* blob_start, size_t blob_size, Verbose = Verbose::No);
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bool dump(FlattenedDeviceTreeHeader const& header, u8 const* blob_start, size_t blob_size);
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}
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