1 //===--------- EHFrameSupport.h - JITLink eh-frame utils --------*- 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 // EHFrame registration support for JITLink. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORT_H 14 #define LLVM_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORT_H 15 16 #include "llvm/ExecutionEngine/JITLink/JITLink.h" 17 #include "llvm/ExecutionEngine/JITSymbol.h" 18 #include "llvm/Support/Error.h" 19 #include "llvm/TargetParser/Triple.h" 20 21 namespace llvm { 22 namespace jitlink { 23 24 /// Inspect an eh-frame CFI record. 25 class EHFrameCFIBlockInspector { 26 public: 27 /// Identify CFI record type and edges based on number and order of edges 28 /// in the given block only. This assumes that the block contains one CFI 29 /// record that has already been split out and fixed by the 30 /// DWARFRecordSplitter and EHFrameEdgeFixer passes. 31 /// 32 /// Zero or one outgoing edges: Record is CIE. If present, edge points to 33 /// personality. 34 /// 35 /// Two or three outgoing edges: Record is an FDE. First edge points to CIE, 36 /// second to PC-begin, third (if present) to LSDA. 37 /// 38 /// It is illegal to call this function on a block with four or more edges. 39 static EHFrameCFIBlockInspector FromEdgeScan(Block &B); 40 41 /// Returns true if this frame is an FDE, false for a CIE. isFDE()42 bool isFDE() const { return CIEEdge != nullptr; } 43 44 /// Returns true if this frame is a CIE, false for an FDE. isCIE()45 bool isCIE() const { return CIEEdge == nullptr; } 46 47 /// If this is a CIE record, returns the Edge pointing at the personality 48 /// function, if any. 49 /// It is illegal to call this method on FDE records. getPersonalityEdge()50 Edge *getPersonalityEdge() const { 51 assert(isCIE() && "CFI record is not a CIE"); 52 return PersonalityEdge; 53 } 54 55 /// If this is an FDE record, returns the Edge pointing to the CIE. 56 /// If this is a CIE record, returns null. 57 /// 58 /// The result is not valid if any modification has been made to the block 59 /// after parsing. getCIEEdge()60 Edge *getCIEEdge() const { return CIEEdge; } 61 62 /// If this is an FDE record, returns the Edge pointing at the PC-begin 63 /// symbol. 64 /// If this a CIE record, returns null. getPCBeginEdge()65 Edge *getPCBeginEdge() const { return PCBeginEdge; } 66 67 /// If this is an FDE record, returns the Edge pointing at the LSDA, if any. 68 /// It is illegal to call this method on CIE records. getLSDAEdge()69 Edge *getLSDAEdge() const { 70 assert(isFDE() && "CFI record is not an FDE"); 71 return LSDAEdge; 72 } 73 74 private: 75 EHFrameCFIBlockInspector(Edge *PersonalityEdge); 76 EHFrameCFIBlockInspector(Edge &CIEEdge, Edge &PCBeginEdge, Edge *LSDAEdge); 77 78 Edge *CIEEdge = nullptr; 79 Edge *PCBeginEdge = nullptr; 80 union { 81 Edge *PersonalityEdge; 82 Edge *LSDAEdge; 83 }; 84 }; 85 86 /// Supports registration/deregistration of EH-frames in a target process. 87 class EHFrameRegistrar { 88 public: 89 virtual ~EHFrameRegistrar(); 90 virtual Error registerEHFrames(orc::ExecutorAddrRange EHFrameSection) = 0; 91 virtual Error deregisterEHFrames(orc::ExecutorAddrRange EHFrameSection) = 0; 92 }; 93 94 /// Registers / Deregisters EH-frames in the current process. 95 class InProcessEHFrameRegistrar final : public EHFrameRegistrar { 96 public: 97 Error registerEHFrames(orc::ExecutorAddrRange EHFrameSection) override; 98 99 Error deregisterEHFrames(orc::ExecutorAddrRange EHFrameSection) override; 100 }; 101 102 using StoreFrameRangeFunction = std::function<void( 103 orc::ExecutorAddr EHFrameSectionAddr, size_t EHFrameSectionSize)>; 104 105 /// Creates a pass that records the address and size of the EH frame section. 106 /// If no eh-frame section is found then the address and size will both be given 107 /// as zero. 108 /// 109 /// Authors of JITLinkContexts can use this function to register a post-fixup 110 /// pass that records the range of the eh-frame section. This range can 111 /// be used after finalization to register and deregister the frame. 112 LinkGraphPassFunction 113 createEHFrameRecorderPass(const Triple &TT, 114 StoreFrameRangeFunction StoreFrameRange); 115 116 } // end namespace jitlink 117 } // end namespace llvm 118 119 #endif // LLVM_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORT_H 120