contrib/llvm/tools/lldb/include/lldb/Symbol/CompactUnwindInfo.h

   1 //===-- CompactUnwindInfo.h -------------------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef liblldb_CompactUnwindInfo_h_
  11 #define liblldb_CompactUnwindInfo_h_
  12
  13 #include <mutex>
  14 #include <vector>
  15
  16 #include "lldb/Core/RangeMap.h"
  17 #include "lldb/Symbol/ObjectFile.h"
  18 #include "lldb/Symbol/UnwindPlan.h"
  19 #include "lldb/Utility/DataExtractor.h"
  20 #include "lldb/lldb-private.h"
  21
  22 namespace lldb_private {
  23
  24 // Compact Unwind info is an unwind format used on Darwin.  The unwind
  25 // instructions for typical compiler-generated functions can be expressed in a
  26 // 32-bit encoding. The format includes a two-level index so the unwind
  27 // information for a function can be found by two binary searches in the
  28 // section.  It can represent both stack frames that use a frame-pointer
  29 // register and frameless functions, on i386/x86_64 for instance.  When a
  30 // function is too complex to be represented in the compact unwind format, it
  31 // calls out to eh_frame unwind instructions.
  32
  33 // On Mac OS X / iOS, a function will have either a compact unwind
  34 // representation or an eh_frame representation.  If lldb is going to benefit
  35 // from the compiler's description about saved register locations, it must be
  36 // able to read both sources of information.
  37
  38 class CompactUnwindInfo {
  39 public:
  40   CompactUnwindInfo(ObjectFile &objfile, lldb::SectionSP &section);
  41
  42   ~CompactUnwindInfo();
  43
  44   bool GetUnwindPlan(Target &target, Address addr, UnwindPlan &unwind_plan);
  45
  46   bool IsValid(const lldb::ProcessSP &process_sp);
  47
  48 private:
  49   // The top level index entries of the compact unwind info
  50   //   (internal representation of struct
  51   //   unwind_info_section_header_index_entry)
  52   // There are relatively few of these (one per 500/1000 functions, depending
  53   // on format) so creating them on first scan will not be too costly.
  54   struct UnwindIndex {
  55     uint32_t function_offset; // The offset of the first function covered by
  56                               // this index
  57     uint32_t second_level; // The offset (inside unwind_info sect) to the second
  58                            // level page for this index
  59     // (either UNWIND_SECOND_LEVEL_REGULAR or UNWIND_SECOND_LEVEL_COMPRESSED)
  60     uint32_t lsda_array_start; // The offset (inside unwind_info sect) LSDA
  61                                // array for this index
  62     uint32_t lsda_array_end; // The offset to the LSDA array for the NEXT index
  63     bool sentinal_entry; // There is an empty index at the end which provides
  64                          // the upper bound of
  65     // function addresses that are described
  66
  67     UnwindIndex()
  68         : function_offset(0), second_level(0), lsda_array_start(0),
  69           lsda_array_end(0), sentinal_entry(false) {}
  70
  71     bool operator<(const CompactUnwindInfo::UnwindIndex &rhs) const {
  72       return function_offset < rhs.function_offset;
  73     }
  74
  75     bool operator==(const CompactUnwindInfo::UnwindIndex &rhs) const {
  76       return function_offset == rhs.function_offset;
  77     }
  78   };
  79
  80   // An internal object used to store the information we retrieve about a
  81   // function -- the encoding bits and possibly the LSDA/personality function.
  82   struct FunctionInfo {
  83     uint32_t encoding;    // compact encoding 32-bit value for this function
  84     Address lsda_address; // the address of the LSDA data for this function
  85     Address personality_ptr_address; // the address where the personality
  86                                      // routine addr can be found
  87
  88     uint32_t valid_range_offset_start; // first offset that this encoding is
  89                                        // valid for (start of the function)
  90     uint32_t
  91         valid_range_offset_end; // the offset of the start of the next function
  92     FunctionInfo()
  93         : encoding(0), lsda_address(), personality_ptr_address(),
  94           valid_range_offset_start(0), valid_range_offset_end(0) {}
  95   };
  96
  97   struct UnwindHeader {
  98     uint32_t version;
  99     uint32_t common_encodings_array_offset;
 100     uint32_t common_encodings_array_count;
 101     uint32_t personality_array_offset;
 102     uint32_t personality_array_count;
 103
 104     UnwindHeader()
 105         : common_encodings_array_offset(0), common_encodings_array_count(0),
 106           personality_array_offset(0), personality_array_count(0) {}
 107   };
 108
 109   void ScanIndex(const lldb::ProcessSP &process_sp);
 110
 111   bool GetCompactUnwindInfoForFunction(Target &target, Address address,
 112                                        FunctionInfo &unwind_info);
 113
 114   lldb::offset_t
 115   BinarySearchRegularSecondPage(uint32_t entry_page_offset,
 116                                 uint32_t entry_count, uint32_t function_offset,
 117                                 uint32_t *entry_func_start_offset,
 118                                 uint32_t *entry_func_end_offset);
 119
 120   uint32_t BinarySearchCompressedSecondPage(uint32_t entry_page_offset,
 121                                             uint32_t entry_count,
 122                                             uint32_t function_offset_to_find,
 123                                             uint32_t function_offset_base,
 124                                             uint32_t *entry_func_start_offset,
 125                                             uint32_t *entry_func_end_offset);
 126
 127   uint32_t GetLSDAForFunctionOffset(uint32_t lsda_offset, uint32_t lsda_count,
 128                                     uint32_t function_offset);
 129
 130   bool CreateUnwindPlan_x86_64(Target &target, FunctionInfo &function_info,
 131                                UnwindPlan &unwind_plan,
 132                                Address pc_or_function_start);
 133
 134   bool CreateUnwindPlan_i386(Target &target, FunctionInfo &function_info,
 135                              UnwindPlan &unwind_plan,
 136                              Address pc_or_function_start);
 137
 138   bool CreateUnwindPlan_arm64(Target &target, FunctionInfo &function_info,
 139                               UnwindPlan &unwind_plan,
 140                               Address pc_or_function_start);
 141
 142   bool CreateUnwindPlan_armv7(Target &target, FunctionInfo &function_info,
 143                               UnwindPlan &unwind_plan,
 144                               Address pc_or_function_start);
 145
 146   ObjectFile &m_objfile;
 147   lldb::SectionSP m_section_sp;
 148   lldb::DataBufferSP m_section_contents_if_encrypted; // if the binary is
 149                                                       // encrypted, read the
 150                                                       // sect contents
 151   // out of live memory and cache them here
 152   std::mutex m_mutex;
 153   std::vector<UnwindIndex> m_indexes;
 154
 155   LazyBool m_indexes_computed; // eLazyBoolYes once we've tried to parse the
 156                                // unwind info
 157   // eLazyBoolNo means we cannot parse the unwind info & should not retry
 158   // eLazyBoolCalculate means we haven't tried to parse it yet
 159
 160   DataExtractor m_unwindinfo_data;
 161   bool m_unwindinfo_data_computed; // true once we've mapped in the unwindinfo
 162                                    // data
 163
 164   UnwindHeader m_unwind_header;
 165 };
 166
 167 } // namespace lldb_private
 168
 169 #endif // liblldb_CompactUnwindInfo_h_