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