1 //===-- DynamicLoader.h -----------------------------------------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef LLDB_TARGET_DYNAMICLOADER_H
10 #define LLDB_TARGET_DYNAMICLOADER_H
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"
23 namespace lldb_private {
29 class SymbolContextList;
33 namespace lldb_private {
35 /// \class DynamicLoader DynamicLoader.h "lldb/Target/DynamicLoader.h"
36 /// A plug-in interface definition class for dynamic loaders.
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.
42 /// Dynamic loader plug-ins can track the process by registering callbacks
43 /// using the: Process::RegisterNotificationCallbacks (const Notifications&)
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 {
54 /// Find a dynamic loader plugin for a given process.
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.
59 /// \param[in] process
60 /// The process for which to try and locate a dynamic loader
63 /// \param[in] plugin_name
64 /// An optional name of a specific dynamic loader plug-in that
65 /// should be used. If empty, pick the best plug-in.
66 static DynamicLoader *FindPlugin(Process *process,
67 llvm::StringRef plugin_name);
69 /// Construct with a process.
70 DynamicLoader(Process *process);
72 /// Called after attaching a process.
74 /// Allow DynamicLoader plug-ins to execute some code after attaching to a
76 virtual void DidAttach() = 0;
78 /// Called after launching a process.
80 /// Allow DynamicLoader plug-ins to execute some code after the process has
81 /// stopped for the first time on launch.
82 virtual void DidLaunch() = 0;
84 /// Helper function that can be used to detect when a process has called
85 /// exec and is now a new and different process. This can be called when
86 /// necessary to try and detect the exec. The process might be able to
87 /// answer this question, but sometimes it might not be able and the dynamic
88 /// loader often knows what the program entry point is. So the process and
89 /// the dynamic loader can work together to detect this.
90 virtual bool ProcessDidExec() { return false; }
91 /// Get whether the process should stop when images change.
93 /// When images (executables and shared libraries) get loaded or unloaded,
94 /// often debug sessions will want to try and resolve or unresolve
95 /// breakpoints that are set in these images. Any breakpoints set by
96 /// DynamicLoader plug-in instances should return this value to ensure
97 /// consistent debug session behaviour.
100 /// Returns \b true if the process should stop when images
101 /// change, \b false if the process should resume.
102 bool GetStopWhenImagesChange() const;
104 /// Set whether the process should stop when images change.
106 /// When images (executables and shared libraries) get loaded or unloaded,
107 /// often debug sessions will want to try and resolve or unresolve
108 /// breakpoints that are set in these images. The default is set so that the
109 /// process stops when images change, but this can be overridden using this
110 /// function callback.
113 /// Boolean value that indicates whether the process should stop
114 /// when images change.
115 void SetStopWhenImagesChange(bool stop);
117 /// Provides a plan to step through the dynamic loader trampoline for the
118 /// current state of \a thread.
121 /// \param[in] stop_others
122 /// Whether the plan should be set to stop other threads.
125 /// A pointer to the plan (caller owned) or NULL if we are not at such
127 virtual lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread,
128 bool stop_others) = 0;
130 /// Some dynamic loaders provide features where there are a group of symbols
131 /// "equivalent to" a given symbol one of which will be chosen when the
132 /// symbol is bound. If you want to set a breakpoint on one of these
133 /// symbols, you really need to set it on all the equivalent symbols.
136 /// \param[in] original_symbol
137 /// The symbol for which we are finding equivalences.
139 /// \param[in] module_list
140 /// The set of modules in which to search.
142 /// \param[out] equivalent_symbols
143 /// The equivalent symbol list - any equivalent symbols found are appended
146 virtual void FindEquivalentSymbols(Symbol *original_symbol,
147 ModuleList &module_list,
148 SymbolContextList &equivalent_symbols) {}
150 /// Ask if it is ok to try and load or unload an shared library (image).
152 /// The dynamic loader often knows when it would be ok to try and load or
153 /// unload a shared library. This function call allows the dynamic loader
154 /// plug-ins to check any current dyld state to make sure it is an ok time
155 /// to load a shared library.
158 /// \b true if it is currently ok to try and load a shared
159 /// library into the process, \b false otherwise.
160 virtual Status CanLoadImage() = 0;
162 /// Ask if the eh_frame information for the given SymbolContext should be
163 /// relied on even when it's the first frame in a stack unwind.
165 /// The CFI instructions from the eh_frame section are normally only valid
166 /// at call sites -- places where a program could throw an exception and
167 /// need to unwind out. But some Modules may be known to the system as
168 /// having reliable eh_frame information at all call sites. This would be
169 /// the case if the Module's contents are largely hand-written assembly with
170 /// hand-written eh_frame information. Normally when unwinding from a
171 /// function at the beginning of a stack unwind lldb will examine the
172 /// assembly instructions to understand how the stack frame is set up and
173 /// where saved registers are stored. But with hand-written assembly this is
174 /// not reliable enough -- we need to consult those function's hand-written
175 /// eh_frame information.
178 /// \b True if the symbol context should use eh_frame instructions
179 /// unconditionally when unwinding from this frame. Else \b false,
180 /// the normal lldb unwind behavior of only using eh_frame when the
181 /// function appears in the middle of the stack.
182 virtual bool AlwaysRelyOnEHUnwindInfo(SymbolContext &sym_ctx) {
186 /// Retrieves the per-module TLS block for a given thread.
188 /// \param[in] module
189 /// The module to query TLS data for.
191 /// \param[in] thread
192 /// The specific thread to query TLS data for.
195 /// If the given thread has TLS data allocated for the
196 /// module, the address of the TLS block. Otherwise
197 /// LLDB_INVALID_ADDRESS is returned.
198 virtual lldb::addr_t GetThreadLocalData(const lldb::ModuleSP module,
199 const lldb::ThreadSP thread,
200 lldb::addr_t tls_file_addr) {
201 return LLDB_INVALID_ADDRESS;
204 /// Locates or creates a module given by \p file and updates/loads the
205 /// resulting module at the virtual base address \p base_addr.
206 virtual lldb::ModuleSP LoadModuleAtAddress(const lldb_private::FileSpec &file,
207 lldb::addr_t link_map_addr,
208 lldb::addr_t base_addr,
209 bool base_addr_is_offset);
211 /// Get information about the shared cache for a process, if possible.
213 /// On some systems (e.g. Darwin based systems), a set of libraries that are
214 /// common to most processes may be put in a single region of memory and
215 /// mapped into every process, this is called the shared cache, as a
216 /// performance optimization.
218 /// Many targets will not have the concept of a shared cache.
220 /// Depending on how the DynamicLoader gathers information about the shared
221 /// cache, it may be able to only return basic information - like the UUID
222 /// of the cache - or it may be able to return additional information about
225 /// \param[out] base_address
226 /// The base address (load address) of the shared cache.
227 /// LLDB_INVALID_ADDRESS if it cannot be determined.
230 /// The UUID of the shared cache, if it can be determined.
231 /// If the UUID cannot be fetched, IsValid() will be false.
233 /// \param[out] using_shared_cache
234 /// If this process is using a shared cache.
235 /// If unknown, eLazyBoolCalculate is returned.
237 /// \param[out] private_shared_cache
238 /// A LazyBool indicating whether this process is using a
239 /// private shared cache.
240 /// If this information cannot be fetched, eLazyBoolCalculate.
243 /// Returns false if this DynamicLoader cannot gather information
244 /// about the shared cache / has no concept of a shared cache.
245 virtual bool GetSharedCacheInformation(lldb::addr_t &base_address, UUID &uuid,
246 LazyBool &using_shared_cache,
247 LazyBool &private_shared_cache) {
248 base_address = LLDB_INVALID_ADDRESS;
250 using_shared_cache = eLazyBoolCalculate;
251 private_shared_cache = eLazyBoolCalculate;
255 /// Return whether the dynamic loader is fully initialized and it's safe to
258 /// On some systems (e.g. Darwin based systems), lldb will get notified by
259 /// the dynamic loader before it itself finished initializing and it's not
260 /// safe to call certain APIs or SPIs.
261 virtual bool IsFullyInitialized() { return true; }
264 // Utility methods for derived classes
266 /// Checks to see if the target module has changed, updates the target
267 /// accordingly and returns the target executable module.
268 lldb::ModuleSP GetTargetExecutable();
270 /// Updates the load address of every allocatable section in \p module.
272 /// \param module The module to traverse.
274 /// \param link_map_addr The virtual address of the link map for the @p
277 /// \param base_addr The virtual base address \p module is loaded at.
278 virtual void UpdateLoadedSections(lldb::ModuleSP module,
279 lldb::addr_t link_map_addr,
280 lldb::addr_t base_addr,
281 bool base_addr_is_offset);
283 // Utility method so base classes can share implementation of
284 // UpdateLoadedSections
285 void UpdateLoadedSectionsCommon(lldb::ModuleSP module, lldb::addr_t base_addr,
286 bool base_addr_is_offset);
288 /// Removes the loaded sections from the target in \p module.
290 /// \param module The module to traverse.
291 virtual void UnloadSections(const lldb::ModuleSP module);
293 // Utility method so base classes can share implementation of UnloadSections
294 void UnloadSectionsCommon(const lldb::ModuleSP module);
296 const lldb_private::SectionList *
297 GetSectionListFromModule(const lldb::ModuleSP module) const;
299 // Read an unsigned int of the given size from memory at the given addr.
300 // Return -1 if the read fails, otherwise return the result as an int64_t.
301 int64_t ReadUnsignedIntWithSizeInBytes(lldb::addr_t addr, int size_in_bytes);
303 // Read a pointer from memory at the given addr. Return LLDB_INVALID_ADDRESS
304 // if the read fails.
305 lldb::addr_t ReadPointer(lldb::addr_t addr);
307 // Calls into the Process protected method LoadOperatingSystemPlugin:
308 void LoadOperatingSystemPlugin(bool flush);
313 *m_process; ///< The process that this dynamic loader plug-in is tracking.
316 } // namespace lldb_private
318 #endif // LLDB_TARGET_DYNAMICLOADER_H