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 liblldb_DynamicLoader_h_
10 #define liblldb_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 NULL, pick the best plug-in.
66 static DynamicLoader *FindPlugin(Process *process, const char *plugin_name);
68 /// Construct with a process.
69 DynamicLoader(Process *process);
73 /// The destructor is virtual since this class is designed to be inherited
74 /// from by the plug-in instance.
75 ~DynamicLoader() override;
77 /// Called after attaching a process.
79 /// Allow DynamicLoader plug-ins to execute some code after attaching to a
81 virtual void DidAttach() = 0;
83 /// Called after launching a process.
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;
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.
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.
105 /// Returns \b true if the process should stop when images
106 /// change, \b false if the process should resume.
107 bool GetStopWhenImagesChange() const;
109 /// Set whether the process should stop when images change.
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.
118 /// Boolean value that indicates whether the process should stop
119 /// when images change.
120 void SetStopWhenImagesChange(bool stop);
122 /// Provides a plan to step through the dynamic loader trampoline for the
123 /// current state of \a thread.
126 /// \param[in] stop_others
127 /// Whether the plan should be set to stop other threads.
130 /// A pointer to the plan (caller owned) or NULL if we are not at such
132 virtual lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread,
133 bool stop_others) = 0;
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.
141 /// \param[in] original_symbol
142 /// The symbol for which we are finding equivalences.
144 /// \param[in] module_list
145 /// The set of modules in which to search.
147 /// \param[out] equivalent_symbols
148 /// The equivalent symbol list - any equivalent symbols found are appended
151 virtual void FindEquivalentSymbols(Symbol *original_symbol,
152 ModuleList &module_list,
153 SymbolContextList &equivalent_symbols) {}
155 /// Ask if it is ok to try and load or unload an shared library (image).
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.
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;
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.
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.
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) {
191 /// Retrieves the per-module TLS block for a given thread.
193 /// \param[in] module
194 /// The module to query TLS data for.
196 /// \param[in] thread
197 /// The specific thread to query TLS data for.
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;
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);
216 /// Get information about the shared cache for a process, if possible.
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.
223 /// Many targets will not have the concept of a shared cache.
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
230 /// \param[out] base_address
231 /// The base address (load address) of the shared cache.
232 /// LLDB_INVALID_ADDRESS if it cannot be determined.
235 /// The UUID of the shared cache, if it can be determined.
236 /// If the UUID cannot be fetched, IsValid() will be false.
238 /// \param[out] using_shared_cache
239 /// If this process is using a shared cache.
240 /// If unknown, eLazyBoolCalculate is returned.
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.
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;
255 using_shared_cache = eLazyBoolCalculate;
256 private_shared_cache = eLazyBoolCalculate;
261 // Utility methods for derived classes
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();
267 /// Updates the load address of every allocatable section in \p module.
269 /// \param module The module to traverse.
271 /// \param link_map_addr The virtual address of the link map for the @p
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);
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);
285 /// Removes the loaded sections from the target in \p module.
287 /// \param module The module to traverse.
288 virtual void UnloadSections(const lldb::ModuleSP module);
290 // Utility method so base classes can share implementation of UnloadSections
291 void UnloadSectionsCommon(const lldb::ModuleSP module);
293 const lldb_private::SectionList *
294 GetSectionListFromModule(const lldb::ModuleSP module) const;
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);
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);
304 // Calls into the Process protected method LoadOperatingSystemPlugin:
305 void LoadOperatingSystemPlugin(bool flush);
310 *m_process; ///< The process that this dynamic loader plug-in is tracking.
313 DISALLOW_COPY_AND_ASSIGN(DynamicLoader);
316 } // namespace lldb_private
318 #endif // liblldb_DynamicLoader_h_