1 //===- Writer.h -------------------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLD_COFF_WRITER_H 10 #define LLD_COFF_WRITER_H 11 12 #include "Chunks.h" 13 #include "llvm/ADT/StringRef.h" 14 #include "llvm/Object/COFF.h" 15 #include <chrono> 16 #include <cstdint> 17 #include <vector> 18 19 namespace lld::coff { 20 static const int pageSize = 4096; 21 class COFFLinkerContext; 22 23 void writeResult(COFFLinkerContext &ctx); 24 25 class PartialSection { 26 public: PartialSection(StringRef n,uint32_t chars)27 PartialSection(StringRef n, uint32_t chars) 28 : name(n), characteristics(chars) {} 29 StringRef name; 30 unsigned characteristics; 31 std::vector<Chunk *> chunks; 32 }; 33 34 // OutputSection represents a section in an output file. It's a 35 // container of chunks. OutputSection and Chunk are 1:N relationship. 36 // Chunks cannot belong to more than one OutputSections. The writer 37 // creates multiple OutputSections and assign them unique, 38 // non-overlapping file offsets and RVAs. 39 class OutputSection { 40 public: OutputSection(llvm::StringRef n,uint32_t chars)41 OutputSection(llvm::StringRef n, uint32_t chars) : name(n) { 42 header.Characteristics = chars; 43 } 44 void addChunk(Chunk *c); 45 void insertChunkAtStart(Chunk *c); 46 void merge(OutputSection *other); 47 void setPermissions(uint32_t c); getRVA()48 uint64_t getRVA() const { return header.VirtualAddress; } getFileOff()49 uint64_t getFileOff() const { return header.PointerToRawData; } 50 void writeHeaderTo(uint8_t *buf, bool isDebug); 51 void addContributingPartialSection(PartialSection *sec); 52 53 // Returns the size of this section in an executable memory image. 54 // This may be smaller than the raw size (the raw size is multiple 55 // of disk sector size, so there may be padding at end), or may be 56 // larger (if that's the case, the loader reserves spaces after end 57 // of raw data). getVirtualSize()58 uint64_t getVirtualSize() { return header.VirtualSize; } 59 60 // Returns the size of the section in the output file. getRawSize()61 uint64_t getRawSize() { return header.SizeOfRawData; } 62 63 // Set offset into the string table storing this section name. 64 // Used only when the name is longer than 8 bytes. setStringTableOff(uint32_t v)65 void setStringTableOff(uint32_t v) { stringTableOff = v; } 66 isCodeSection()67 bool isCodeSection() const { 68 return (header.Characteristics & llvm::COFF::IMAGE_SCN_CNT_CODE) && 69 (header.Characteristics & llvm::COFF::IMAGE_SCN_MEM_READ) && 70 (header.Characteristics & llvm::COFF::IMAGE_SCN_MEM_EXECUTE); 71 } 72 73 // N.B. The section index is one based. 74 uint32_t sectionIndex = 0; 75 76 llvm::StringRef name; 77 llvm::object::coff_section header = {}; 78 79 std::vector<Chunk *> chunks; 80 std::vector<Chunk *> origChunks; 81 82 std::vector<PartialSection *> contribSections; 83 84 private: 85 uint32_t stringTableOff = 0; 86 }; 87 88 } // namespace lld::coff 89 90 #endif 91