1 //===-- DynamicLoader.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 liblldb_DynamicLoader_h_ 10 #define liblldb_DynamicLoader_h_ 11 12 #include "lldb/Core/PluginInterface.h" 13 #include "lldb/Utility/FileSpec.h" 14 #include "lldb/Utility/Status.h" 15 #include "lldb/Utility/UUID.h" 16 #include "lldb/lldb-defines.h" 17 #include "lldb/lldb-forward.h" 18 #include "lldb/lldb-private-enumerations.h" 19 #include "lldb/lldb-types.h" 20 21 #include <stddef.h> 22 #include <stdint.h> 23 namespace lldb_private { 24 class ModuleList; 25 class Process; 26 class SectionList; 27 class Symbol; 28 class SymbolContext; 29 class SymbolContextList; 30 class Thread; 31 } 32 33 namespace lldb_private { 34 35 /// \class DynamicLoader DynamicLoader.h "lldb/Target/DynamicLoader.h" 36 /// A plug-in interface definition class for dynamic loaders. 37 /// 38 /// Dynamic loader plug-ins track image (shared library) loading and 39 /// unloading. The class is initialized given a live process that is halted at 40 /// its entry point or just after attaching. 41 /// 42 /// Dynamic loader plug-ins can track the process by registering callbacks 43 /// using the: Process::RegisterNotificationCallbacks (const Notifications&) 44 /// function. 45 /// 46 /// Breakpoints can also be set in the process which can register functions 47 /// that get called using: Process::BreakpointSetCallback (lldb::user_id_t, 48 /// BreakpointHitCallback, void *). These breakpoint callbacks return a 49 /// boolean value that indicates if the process should continue or halt and 50 /// should return the global setting for this using: 51 /// DynamicLoader::StopWhenImagesChange() const. 52 class DynamicLoader : public PluginInterface { 53 public: 54 /// Find a dynamic loader plugin for a given process. 55 /// 56 /// Scans the installed DynamicLoader plug-ins and tries to find an instance 57 /// that can be used to track image changes in \a process. 58 /// 59 /// \param[in] process 60 /// The process for which to try and locate a dynamic loader 61 /// plug-in instance. 62 /// 63 /// \param[in] plugin_name 64 /// An optional name of a specific dynamic loader plug-in that 65 /// should be used. If NULL, pick the best plug-in. 66 static DynamicLoader *FindPlugin(Process *process, const char *plugin_name); 67 68 /// Construct with a process. 69 DynamicLoader(Process *process); 70 71 /// Destructor. 72 /// 73 /// The destructor is virtual since this class is designed to be inherited 74 /// from by the plug-in instance. 75 ~DynamicLoader() override; 76 77 /// Called after attaching a process. 78 /// 79 /// Allow DynamicLoader plug-ins to execute some code after attaching to a 80 /// process. 81 virtual void DidAttach() = 0; 82 83 /// Called after launching a process. 84 /// 85 /// Allow DynamicLoader plug-ins to execute some code after the process has 86 /// stopped for the first time on launch. 87 virtual void DidLaunch() = 0; 88 89 /// Helper function that can be used to detect when a process has called 90 /// exec and is now a new and different process. This can be called when 91 /// necessary to try and detect the exec. The process might be able to 92 /// answer this question, but sometimes it might not be able and the dynamic 93 /// loader often knows what the program entry point is. So the process and 94 /// the dynamic loader can work together to detect this. 95 virtual bool ProcessDidExec() { return false; } 96 /// Get whether the process should stop when images change. 97 /// 98 /// When images (executables and shared libraries) get loaded or unloaded, 99 /// often debug sessions will want to try and resolve or unresolve 100 /// breakpoints that are set in these images. Any breakpoints set by 101 /// DynamicLoader plug-in instances should return this value to ensure 102 /// consistent debug session behaviour. 103 /// 104 /// \return 105 /// Returns \b true if the process should stop when images 106 /// change, \b false if the process should resume. 107 bool GetStopWhenImagesChange() const; 108 109 /// Set whether the process should stop when images change. 110 /// 111 /// When images (executables and shared libraries) get loaded or unloaded, 112 /// often debug sessions will want to try and resolve or unresolve 113 /// breakpoints that are set in these images. The default is set so that the 114 /// process stops when images change, but this can be overridden using this 115 /// function callback. 116 /// 117 /// \param[in] stop 118 /// Boolean value that indicates whether the process should stop 119 /// when images change. 120 void SetStopWhenImagesChange(bool stop); 121 122 /// Provides a plan to step through the dynamic loader trampoline for the 123 /// current state of \a thread. 124 /// 125 /// 126 /// \param[in] stop_others 127 /// Whether the plan should be set to stop other threads. 128 /// 129 /// \return 130 /// A pointer to the plan (caller owned) or NULL if we are not at such 131 /// a trampoline. 132 virtual lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread, 133 bool stop_others) = 0; 134 135 /// Some dynamic loaders provide features where there are a group of symbols 136 /// "equivalent to" a given symbol one of which will be chosen when the 137 /// symbol is bound. If you want to set a breakpoint on one of these 138 /// symbols, you really need to set it on all the equivalent symbols. 139 /// 140 /// 141 /// \param[in] original_symbol 142 /// The symbol for which we are finding equivalences. 143 /// 144 /// \param[in] module_list 145 /// The set of modules in which to search. 146 /// 147 /// \param[out] equivalent_symbols 148 /// The equivalent symbol list - any equivalent symbols found are appended 149 /// to this list. 150 /// 151 virtual void FindEquivalentSymbols(Symbol *original_symbol, 152 ModuleList &module_list, 153 SymbolContextList &equivalent_symbols) {} 154 155 /// Ask if it is ok to try and load or unload an shared library (image). 156 /// 157 /// The dynamic loader often knows when it would be ok to try and load or 158 /// unload a shared library. This function call allows the dynamic loader 159 /// plug-ins to check any current dyld state to make sure it is an ok time 160 /// to load a shared library. 161 /// 162 /// \return 163 /// \b true if it is currently ok to try and load a shared 164 /// library into the process, \b false otherwise. 165 virtual Status CanLoadImage() = 0; 166 167 /// Ask if the eh_frame information for the given SymbolContext should be 168 /// relied on even when it's the first frame in a stack unwind. 169 /// 170 /// The CFI instructions from the eh_frame section are normally only valid 171 /// at call sites -- places where a program could throw an exception and 172 /// need to unwind out. But some Modules may be known to the system as 173 /// having reliable eh_frame information at all call sites. This would be 174 /// the case if the Module's contents are largely hand-written assembly with 175 /// hand-written eh_frame information. Normally when unwinding from a 176 /// function at the beginning of a stack unwind lldb will examine the 177 /// assembly instructions to understand how the stack frame is set up and 178 /// where saved registers are stored. But with hand-written assembly this is 179 /// not reliable enough -- we need to consult those function's hand-written 180 /// eh_frame information. 181 /// 182 /// \return 183 /// \b True if the symbol context should use eh_frame instructions 184 /// unconditionally when unwinding from this frame. Else \b false, 185 /// the normal lldb unwind behavior of only using eh_frame when the 186 /// function appears in the middle of the stack. 187 virtual bool AlwaysRelyOnEHUnwindInfo(SymbolContext &sym_ctx) { 188 return false; 189 } 190 191 /// Retrieves the per-module TLS block for a given thread. 192 /// 193 /// \param[in] module 194 /// The module to query TLS data for. 195 /// 196 /// \param[in] thread 197 /// The specific thread to query TLS data for. 198 /// 199 /// \return 200 /// If the given thread has TLS data allocated for the 201 /// module, the address of the TLS block. Otherwise 202 /// LLDB_INVALID_ADDRESS is returned. 203 virtual lldb::addr_t GetThreadLocalData(const lldb::ModuleSP module, 204 const lldb::ThreadSP thread, 205 lldb::addr_t tls_file_addr) { 206 return LLDB_INVALID_ADDRESS; 207 } 208 209 /// Locates or creates a module given by \p file and updates/loads the 210 /// resulting module at the virtual base address \p base_addr. 211 virtual lldb::ModuleSP LoadModuleAtAddress(const lldb_private::FileSpec &file, 212 lldb::addr_t link_map_addr, 213 lldb::addr_t base_addr, 214 bool base_addr_is_offset); 215 216 /// Get information about the shared cache for a process, if possible. 217 /// 218 /// On some systems (e.g. Darwin based systems), a set of libraries that are 219 /// common to most processes may be put in a single region of memory and 220 /// mapped into every process, this is called the shared cache, as a 221 /// performance optimization. 222 /// 223 /// Many targets will not have the concept of a shared cache. 224 /// 225 /// Depending on how the DynamicLoader gathers information about the shared 226 /// cache, it may be able to only return basic information - like the UUID 227 /// of the cache - or it may be able to return additional information about 228 /// the cache. 229 /// 230 /// \param[out] base_address 231 /// The base address (load address) of the shared cache. 232 /// LLDB_INVALID_ADDRESS if it cannot be determined. 233 /// 234 /// \param[out] uuid 235 /// The UUID of the shared cache, if it can be determined. 236 /// If the UUID cannot be fetched, IsValid() will be false. 237 /// 238 /// \param[out] using_shared_cache 239 /// If this process is using a shared cache. 240 /// If unknown, eLazyBoolCalculate is returned. 241 /// 242 /// \param[out] private_shared_cache 243 /// A LazyBool indicating whether this process is using a 244 /// private shared cache. 245 /// If this information cannot be fetched, eLazyBoolCalculate. 246 /// 247 /// \return 248 /// Returns false if this DynamicLoader cannot gather information 249 /// about the shared cache / has no concept of a shared cache. 250 virtual bool GetSharedCacheInformation(lldb::addr_t &base_address, UUID &uuid, 251 LazyBool &using_shared_cache, 252 LazyBool &private_shared_cache) { 253 base_address = LLDB_INVALID_ADDRESS; 254 uuid.Clear(); 255 using_shared_cache = eLazyBoolCalculate; 256 private_shared_cache = eLazyBoolCalculate; 257 return false; 258 } 259 260 protected: 261 // Utility methods for derived classes 262 263 /// Checks to see if the target module has changed, updates the target 264 /// accordingly and returns the target executable module. 265 lldb::ModuleSP GetTargetExecutable(); 266 267 /// Updates the load address of every allocatable section in \p module. 268 /// 269 /// \param module The module to traverse. 270 /// 271 /// \param link_map_addr The virtual address of the link map for the @p 272 /// module. 273 /// 274 /// \param base_addr The virtual base address \p module is loaded at. 275 virtual void UpdateLoadedSections(lldb::ModuleSP module, 276 lldb::addr_t link_map_addr, 277 lldb::addr_t base_addr, 278 bool base_addr_is_offset); 279 280 // Utility method so base classes can share implementation of 281 // UpdateLoadedSections 282 void UpdateLoadedSectionsCommon(lldb::ModuleSP module, lldb::addr_t base_addr, 283 bool base_addr_is_offset); 284 285 /// Removes the loaded sections from the target in \p module. 286 /// 287 /// \param module The module to traverse. 288 virtual void UnloadSections(const lldb::ModuleSP module); 289 290 // Utility method so base classes can share implementation of UnloadSections 291 void UnloadSectionsCommon(const lldb::ModuleSP module); 292 293 const lldb_private::SectionList * 294 GetSectionListFromModule(const lldb::ModuleSP module) const; 295 296 // Read an unsigned int of the given size from memory at the given addr. 297 // Return -1 if the read fails, otherwise return the result as an int64_t. 298 int64_t ReadUnsignedIntWithSizeInBytes(lldb::addr_t addr, int size_in_bytes); 299 300 // Read a pointer from memory at the given addr. Return LLDB_INVALID_ADDRESS 301 // if the read fails. 302 lldb::addr_t ReadPointer(lldb::addr_t addr); 303 304 // Calls into the Process protected method LoadOperatingSystemPlugin: 305 void LoadOperatingSystemPlugin(bool flush); 306 307 308 // Member variables. 309 Process 310 *m_process; ///< The process that this dynamic loader plug-in is tracking. 311 312 private: 313 DISALLOW_COPY_AND_ASSIGN(DynamicLoader); 314 }; 315 316 } // namespace lldb_private 317 318 #endif // liblldb_DynamicLoader_h_ 319