1 //===-- DWARFCallFrameInfo.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 LLDB_SYMBOL_DWARFCALLFRAMEINFO_H
10 #define LLDB_SYMBOL_DWARFCALLFRAMEINFO_H
11 
12 #include <map>
13 #include <mutex>
14 #include <optional>
15 
16 #include "lldb/Core/AddressRange.h"
17 #include "lldb/Core/dwarf.h"
18 #include "lldb/Symbol/ObjectFile.h"
19 #include "lldb/Symbol/UnwindPlan.h"
20 #include "lldb/Utility/Flags.h"
21 #include "lldb/Utility/RangeMap.h"
22 #include "lldb/Utility/VMRange.h"
23 #include "lldb/lldb-private.h"
24 
25 namespace lldb_private {
26 
27 // DWARFCallFrameInfo is a class which can read eh_frame and DWARF Call Frame
28 // Information FDEs.  It stores little information internally. Only two APIs
29 // are exported - one to find the high/low pc values of a function given a text
30 // address via the information in the eh_frame / debug_frame, and one to
31 // generate an UnwindPlan based on the FDE in the eh_frame / debug_frame
32 // section.
33 
34 class DWARFCallFrameInfo {
35 public:
36   enum Type { EH, DWARF };
37 
38   DWARFCallFrameInfo(ObjectFile &objfile, lldb::SectionSP &section, Type type);
39 
40   ~DWARFCallFrameInfo() = default;
41 
42   // Locate an AddressRange that includes the provided Address in this object's
43   // eh_frame/debug_info Returns true if a range is found to cover that
44   // address.
45   bool GetAddressRange(Address addr, AddressRange &range);
46 
47   /// Return an UnwindPlan based on the call frame information encoded in the
48   /// FDE of this DWARFCallFrameInfo section. The returned plan will be valid
49   /// (at least) for the given address.
50   bool GetUnwindPlan(const Address &addr, UnwindPlan &unwind_plan);
51 
52   /// Return an UnwindPlan based on the call frame information encoded in the
53   /// FDE of this DWARFCallFrameInfo section. The returned plan will be valid
54   /// (at least) for some address in the given range.
55   bool GetUnwindPlan(const AddressRange &range, UnwindPlan &unwind_plan);
56 
57   typedef RangeVector<lldb::addr_t, uint32_t> FunctionAddressAndSizeVector;
58 
59   // Build a vector of file address and size for all functions in this Module
60   // based on the eh_frame FDE entries.
61   //
62   // The eh_frame information can be a useful source of file address and size
63   // of the functions in a Module.  Often a binary's non-exported symbols are
64   // stripped before shipping so lldb won't know the start addr / size of many
65   // functions in the Module.  But the eh_frame can help to give the addresses
66   // of these stripped symbols, at least.
67   //
68   // \param[out] function_info
69   //      A vector provided by the caller is filled out.  May be empty if no
70   //      FDEs/no eh_frame
71   //      is present in this Module.
72 
73   void
74   GetFunctionAddressAndSizeVector(FunctionAddressAndSizeVector &function_info);
75 
76   void ForEachFDEEntries(
77       const std::function<bool(lldb::addr_t, uint32_t, dw_offset_t)> &callback);
78 
79 private:
80   enum { CFI_AUG_MAX_SIZE = 8, CFI_HEADER_SIZE = 8 };
81   enum CFIVersion {
82     CFI_VERSION1 = 1, // DWARF v.2
83     CFI_VERSION3 = 3, // DWARF v.3
84     CFI_VERSION4 = 4  // DWARF v.4, v.5
85   };
86 
87   struct CIE {
88     dw_offset_t cie_offset;
89     uint8_t version;
90     char augmentation[CFI_AUG_MAX_SIZE]; // This is typically empty or very
91                                          // short.
92     uint8_t address_size = sizeof(uint32_t); // The size of a target address.
93     uint8_t segment_size = 0;                // The size of a segment selector.
94 
95     uint32_t code_align;
96     int32_t data_align;
97     uint32_t return_addr_reg_num;
98     dw_offset_t inst_offset; // offset of CIE instructions in mCFIData
99     uint32_t inst_length;    // length of CIE instructions in mCFIData
100     uint8_t ptr_encoding;
101     uint8_t lsda_addr_encoding;   // The encoding of the LSDA address in the FDE
102                                   // augmentation data
103     lldb::addr_t personality_loc; // (file) address of the pointer to the
104                                   // personality routine
105     lldb_private::UnwindPlan::Row initial_row;
106 
107     CIE(dw_offset_t offset)
108         : cie_offset(offset), version(-1), code_align(0), data_align(0),
109           return_addr_reg_num(LLDB_INVALID_REGNUM), inst_offset(0),
110           inst_length(0), ptr_encoding(0),
111           lsda_addr_encoding(llvm::dwarf::DW_EH_PE_omit),
112           personality_loc(LLDB_INVALID_ADDRESS) {}
113   };
114 
115   typedef std::shared_ptr<CIE> CIESP;
116 
117   typedef std::map<dw_offset_t, CIESP> cie_map_t;
118 
119   // Start address (file address), size, offset of FDE location used for
120   // finding an FDE for a given File address; the start address field is an
121   // offset into an individual Module.
122   typedef RangeDataVector<lldb::addr_t, uint32_t, dw_offset_t> FDEEntryMap;
123 
124   bool IsEHFrame() const;
125 
126   std::optional<FDEEntryMap::Entry>
127   GetFirstFDEEntryInRange(const AddressRange &range);
128 
129   void GetFDEIndex();
130 
131   bool FDEToUnwindPlan(uint32_t offset, Address startaddr,
132                        UnwindPlan &unwind_plan);
133 
134   const CIE *GetCIE(dw_offset_t cie_offset);
135 
136   void GetCFIData();
137 
138   // Applies the specified DWARF opcode to the given row. This function handle
139   // the commands operates only on a single row (these are the ones what can
140   // appear both in
141   // CIE and in FDE).
142   // Returns true if the opcode is handled and false otherwise.
143   bool HandleCommonDwarfOpcode(uint8_t primary_opcode, uint8_t extended_opcode,
144                                int32_t data_align, lldb::offset_t &offset,
145                                UnwindPlan::Row &row);
146 
147   ObjectFile &m_objfile;
148   lldb::SectionSP m_section_sp;
149   Flags m_flags = 0;
150   cie_map_t m_cie_map;
151 
152   DataExtractor m_cfi_data;
153   bool m_cfi_data_initialized = false; // only copy the section into the DE once
154 
155   FDEEntryMap m_fde_index;
156   bool m_fde_index_initialized = false; // only scan the section for FDEs once
157   std::mutex m_fde_index_mutex; // and isolate the thread that does it
158 
159   Type m_type;
160 
161   CIESP
162   ParseCIE(const uint32_t cie_offset);
163 
164   lldb::RegisterKind GetRegisterKind() const {
165     return m_type == EH ? lldb::eRegisterKindEHFrame : lldb::eRegisterKindDWARF;
166   }
167 };
168 
169 } // namespace lldb_private
170 
171 #endif // LLDB_SYMBOL_DWARFCALLFRAMEINFO_H
172