1 //===-- DYLDRendezvous.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_SOURCE_PLUGINS_DYNAMICLOADER_POSIX_DYLD_DYLDRENDEZVOUS_H 10 #define LLDB_SOURCE_PLUGINS_DYNAMICLOADER_POSIX_DYLD_DYLDRENDEZVOUS_H 11 12 #include <list> 13 #include <string> 14 15 #include "lldb/Utility/FileSpec.h" 16 #include "lldb/lldb-defines.h" 17 #include "lldb/lldb-types.h" 18 19 #include "lldb/Core/LoadedModuleInfoList.h" 20 21 using lldb_private::LoadedModuleInfoList; 22 23 namespace lldb_private { 24 class Process; 25 } 26 27 /// \class DYLDRendezvous 28 /// Interface to the runtime linker. 29 /// 30 /// A structure is present in a processes memory space which is updated by the 31 /// runtime liker each time a module is loaded or unloaded. This class 32 /// provides an interface to this structure and maintains a consistent 33 /// snapshot of the currently loaded modules. 34 class DYLDRendezvous { 35 36 // This structure is used to hold the contents of the debug rendezvous 37 // information (struct r_debug) as found in the inferiors memory. Note that 38 // the layout of this struct is not binary compatible, it is simply large 39 // enough to hold the information on both 32 and 64 bit platforms. 40 struct Rendezvous { 41 uint64_t version; 42 lldb::addr_t map_addr; 43 lldb::addr_t brk; 44 uint64_t state; 45 lldb::addr_t ldbase; 46 RendezvousRendezvous47 Rendezvous() : version(0), map_addr(0), brk(0), state(0), ldbase(0) {} 48 }; 49 50 public: 51 // Various metadata supplied by the inferior's threading library to describe 52 // the per-thread state. 53 struct ThreadInfo { 54 bool valid; // whether we read valid metadata 55 uint32_t dtv_offset; // offset of DTV pointer within pthread 56 uint32_t dtv_slot_size; // size of one DTV slot 57 uint32_t modid_offset; // offset of module ID within link_map 58 uint32_t tls_offset; // offset of TLS pointer within DTV slot 59 }; 60 61 DYLDRendezvous(lldb_private::Process *process); 62 63 /// Update the internal snapshot of runtime linker rendezvous and recompute 64 /// the currently loaded modules. 65 /// 66 /// This method should be called once one start up, then once each time the 67 /// runtime linker enters the function given by GetBreakAddress(). 68 /// 69 /// \returns true on success and false on failure. 70 /// 71 /// \see GetBreakAddress(). 72 bool Resolve(); 73 74 /// \returns true if this rendezvous has been located in the inferiors 75 /// address space and false otherwise. 76 bool IsValid(); 77 78 /// \returns the address of the rendezvous structure in the inferiors 79 /// address space. GetRendezvousAddress()80 lldb::addr_t GetRendezvousAddress() const { return m_rendezvous_addr; } 81 82 /// \returns the version of the rendezvous protocol being used. GetVersion()83 uint64_t GetVersion() const { return m_current.version; } 84 85 /// \returns address in the inferiors address space containing the linked 86 /// list of shared object descriptors. GetLinkMapAddress()87 lldb::addr_t GetLinkMapAddress() const { return m_current.map_addr; } 88 89 /// A breakpoint should be set at this address and Resolve called on each 90 /// hit. 91 /// 92 /// \returns the address of a function called by the runtime linker each 93 /// time a module is loaded/unloaded, or about to be loaded/unloaded. 94 /// 95 /// \see Resolve() GetBreakAddress()96 lldb::addr_t GetBreakAddress() const { return m_current.brk; } 97 98 /// Returns the current state of the rendezvous structure. GetState()99 uint64_t GetState() const { return m_current.state; } 100 101 /// \returns the base address of the runtime linker in the inferiors address 102 /// space. GetLDBase()103 lldb::addr_t GetLDBase() const { return m_current.ldbase; } 104 105 /// \returns the thread layout metadata from the inferiors thread library. 106 const ThreadInfo &GetThreadInfo(); 107 108 /// \returns true if modules have been loaded into the inferior since the 109 /// last call to Resolve(). ModulesDidLoad()110 bool ModulesDidLoad() const { return !m_added_soentries.empty(); } 111 112 /// \returns true if modules have been unloaded from the inferior since the 113 /// last call to Resolve(). ModulesDidUnload()114 bool ModulesDidUnload() const { return !m_removed_soentries.empty(); } 115 116 void DumpToLog(lldb_private::Log *log) const; 117 118 /// Constants describing the state of the rendezvous. 119 /// 120 /// \see GetState(). 121 enum RendezvousState { eConsistent, eAdd, eDelete }; 122 123 /// Structure representing the shared objects currently loaded into the 124 /// inferior process. 125 /// 126 /// This object is a rough analogue to the struct link_map object which 127 /// actually lives in the inferiors memory. 128 struct SOEntry { 129 lldb::addr_t link_addr; ///< Address of this link_map. 130 lldb::addr_t base_addr; ///< Base address of the loaded object. 131 lldb::addr_t path_addr; ///< String naming the shared object. 132 lldb::addr_t dyn_addr; ///< Dynamic section of shared object. 133 lldb::addr_t next; ///< Address of next so_entry. 134 lldb::addr_t prev; ///< Address of previous so_entry. 135 lldb_private::FileSpec file_spec; ///< File spec of shared object. 136 SOEntrySOEntry137 SOEntry() { clear(); } 138 139 bool operator==(const SOEntry &entry) { 140 return file_spec == entry.file_spec; 141 } 142 clearSOEntry143 void clear() { 144 link_addr = 0; 145 base_addr = 0; 146 path_addr = 0; 147 dyn_addr = 0; 148 next = 0; 149 prev = 0; 150 file_spec.Clear(); 151 } 152 }; 153 154 protected: 155 typedef std::list<SOEntry> SOEntryList; 156 157 public: 158 typedef SOEntryList::const_iterator iterator; 159 160 /// Iterators over all currently loaded modules. begin()161 iterator begin() const { return m_soentries.begin(); } end()162 iterator end() const { return m_soentries.end(); } 163 164 /// Iterators over all modules loaded into the inferior since the last call 165 /// to Resolve(). loaded_begin()166 iterator loaded_begin() const { return m_added_soentries.begin(); } loaded_end()167 iterator loaded_end() const { return m_added_soentries.end(); } 168 169 /// Iterators over all modules unloaded from the inferior since the last 170 /// call to Resolve(). unloaded_begin()171 iterator unloaded_begin() const { return m_removed_soentries.begin(); } unloaded_end()172 iterator unloaded_end() const { return m_removed_soentries.end(); } 173 174 protected: 175 lldb_private::Process *m_process; 176 177 // Cached copy of executable file spec 178 lldb_private::FileSpec m_exe_file_spec; 179 180 /// Location of the r_debug structure in the inferiors address space. 181 lldb::addr_t m_rendezvous_addr; 182 183 /// Current and previous snapshots of the rendezvous structure. 184 Rendezvous m_current; 185 Rendezvous m_previous; 186 187 /// List of currently loaded SO modules 188 LoadedModuleInfoList m_loaded_modules; 189 190 /// List of SOEntry objects corresponding to the current link map state. 191 SOEntryList m_soentries; 192 193 /// List of SOEntry's added to the link map since the last call to 194 /// Resolve(). 195 SOEntryList m_added_soentries; 196 197 /// List of SOEntry's removed from the link map since the last call to 198 /// Resolve(). 199 SOEntryList m_removed_soentries; 200 201 /// Threading metadata read from the inferior. 202 ThreadInfo m_thread_info; 203 204 /// Reads an unsigned integer of \p size bytes from the inferior's address 205 /// space starting at \p addr. 206 /// 207 /// \returns addr + size if the read was successful and false otherwise. 208 lldb::addr_t ReadWord(lldb::addr_t addr, uint64_t *dst, size_t size); 209 210 /// Reads an address from the inferior's address space starting at \p addr. 211 /// 212 /// \returns addr + target address size if the read was successful and 213 /// 0 otherwise. 214 lldb::addr_t ReadPointer(lldb::addr_t addr, lldb::addr_t *dst); 215 216 /// Reads a null-terminated C string from the memory location starting at @p 217 /// addr. 218 std::string ReadStringFromMemory(lldb::addr_t addr); 219 220 /// Reads an SOEntry starting at \p addr. 221 bool ReadSOEntryFromMemory(lldb::addr_t addr, SOEntry &entry); 222 223 /// Updates the current set of SOEntries, the set of added entries, and the 224 /// set of removed entries. 225 bool UpdateSOEntries(); 226 227 /// Same as UpdateSOEntries but it gets the list of loaded modules from the 228 /// remote debug server (faster when supported). 229 bool UpdateSOEntriesFromRemote(); 230 231 bool FillSOEntryFromModuleInfo( 232 LoadedModuleInfoList::LoadedModuleInfo const &modInfo, SOEntry &entry); 233 234 bool SaveSOEntriesFromRemote(const LoadedModuleInfoList &module_list); 235 236 bool AddSOEntriesFromRemote(const LoadedModuleInfoList &module_list); 237 238 bool RemoveSOEntriesFromRemote(const LoadedModuleInfoList &module_list); 239 240 bool AddSOEntries(); 241 242 bool RemoveSOEntries(); 243 244 void UpdateBaseAddrIfNecessary(SOEntry &entry, std::string const &file_path); 245 246 bool SOEntryIsMainExecutable(const SOEntry &entry); 247 248 /// Reads the current list of shared objects according to the link map 249 /// supplied by the runtime linker. 250 bool TakeSnapshot(SOEntryList &entry_list); 251 252 enum PThreadField { eSize, eNElem, eOffset }; 253 254 bool FindMetadata(const char *name, PThreadField field, uint32_t &value); 255 256 enum RendezvousAction { 257 eNoAction, 258 eTakeSnapshot, 259 eAddModules, 260 eRemoveModules 261 }; 262 263 /// Returns the current action to be taken given the current and previous 264 /// state 265 RendezvousAction GetAction() const; 266 }; 267 268 #endif 269