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