//===-- ObjCTrampolineHandler.cpp ----------------------------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "ObjCTrampolineHandler.h" // C Includes // C++ Includes // Other libraries and framework includes // Project includes #include "lldb/Core/Module.h" #include "lldb/Core/ConstString.h" #include "lldb/Core/FileSpec.h" #include "lldb/Target/Thread.h" #include "lldb/Target/RegisterContext.h" #include "lldb/Target/Target.h" #include "lldb/Target/Process.h" #include "lldb/Core/Value.h" #include "lldb/Symbol/ClangASTContext.h" #include "lldb/Expression/ClangFunction.h" #include "lldb/Core/Log.h" #include "lldb/Target/ExecutionContext.h" #include "ThreadPlanStepThroughObjCTrampoline.h" #include "lldb/Target/ThreadPlanRunToAddress.h" using namespace lldb; using namespace lldb_private; const ObjCTrampolineHandler::DispatchFunction ObjCTrampolineHandler::g_dispatch_functions[] = { // NAME STRET SUPER FIXUP TYPE {"objc_msgSend", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSend_fixup", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpToFix }, {"objc_msgSend_fixedup", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpFixed }, {"objc_msgSend_stret", true, false, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSend_stret_fixup", true, false, ObjCTrampolineHandler::DispatchFunction::eFixUpToFix }, {"objc_msgSend_stret_fixedup", true, false, ObjCTrampolineHandler::DispatchFunction::eFixUpFixed }, {"objc_msgSend_fpret", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSend_fpret_fixup", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpToFix }, {"objc_msgSend_fpret_fixedup", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpFixed }, {"objc_msgSend_fp2ret", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSend_fp2ret_fixup", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpToFix }, {"objc_msgSend_fp2ret_fixedup", false, false, ObjCTrampolineHandler::DispatchFunction::eFixUpFixed }, {"objc_msgSendSuper", false, true, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSendSuper_stret", true, true, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSendSuper2", false, true, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSendSuper2_fixup", false, true, ObjCTrampolineHandler::DispatchFunction::eFixUpToFix }, {"objc_msgSendSuper2_fixedup", false, true, ObjCTrampolineHandler::DispatchFunction::eFixUpFixed }, {"objc_msgSendSuper2_stret", true, true, ObjCTrampolineHandler::DispatchFunction::eFixUpNone }, {"objc_msgSendSuper2_stret_fixup", true, true, ObjCTrampolineHandler::DispatchFunction::eFixUpToFix }, {"objc_msgSendSuper2_stret_fixedup", true, true, ObjCTrampolineHandler::DispatchFunction::eFixUpFixed }, {NULL} }; bool ObjCTrampolineHandler::ModuleIsObjCLibrary (const ModuleSP &module_sp) { const FileSpec &module_file_spec = module_sp->GetFileSpec(); static ConstString ObjCName ("libobjc.A.dylib"); if (module_file_spec) { if (module_file_spec.GetFilename() == ObjCName) return true; } return false; } ObjCTrampolineHandler::ObjCTrampolineHandler (ProcessSP process_sp, ModuleSP objc_module) : m_process_sp (process_sp), m_objc_module_sp (objc_module), m_impl_fn_addr (LLDB_INVALID_ADDRESS), m_impl_stret_fn_addr (LLDB_INVALID_ADDRESS) { // Look up the known resolution functions: ConstString get_impl_name("class_getMethodImplementation"); ConstString get_impl_stret_name("class_getMethodImplementation_stret"); const Symbol *class_getMethodImplementation = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_name, eSymbolTypeCode); const Symbol *class_getMethodImplementation_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_stret_name, eSymbolTypeCode); if (class_getMethodImplementation) m_impl_fn_addr = class_getMethodImplementation->GetValue().GetLoadAddress(m_process_sp.get()); if (class_getMethodImplementation_stret) m_impl_stret_fn_addr = class_getMethodImplementation_stret->GetValue().GetLoadAddress(m_process_sp.get()); // FIXME: Do some kind of logging here. if (m_impl_fn_addr == LLDB_INVALID_ADDRESS || m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) return; // Look up the addresses for the objc dispatch functions and cache them. For now I'm inspecting the symbol // names dynamically to figure out how to dispatch to them. If it becomes more complicated than this we can // turn the g_dispatch_functions char * array into a template table, and populate the DispatchFunction map // from there. for (int i = 0; g_dispatch_functions[i].name != NULL; i++) { ConstString name_const_str(g_dispatch_functions[i].name); const Symbol *msgSend_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (name_const_str, eSymbolTypeCode); if (msgSend_symbol) { // FixMe: Make g_dispatch_functions static table of DisptachFunctions, and have the map be address->index. // Problem is we also need to lookup the dispatch function. For now we could have a side table of stret & non-stret // dispatch functions. If that's as complex as it gets, we're fine. lldb::addr_t sym_addr = msgSend_symbol->GetValue().GetLoadAddress(m_process_sp.get()); m_msgSend_map.insert(std::pair(sym_addr, i)); } } } ThreadPlanSP ObjCTrampolineHandler::GetStepThroughDispatchPlan (Thread &thread, bool stop_others) { ThreadPlanSP ret_plan_sp; lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); MsgsendMap::iterator pos; pos = m_msgSend_map.find (curr_pc); if (pos != m_msgSend_map.end()) { Log *log = lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP); const DispatchFunction *this_dispatch = &g_dispatch_functions[(*pos).second]; lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); Process *process = thread.CalculateProcess(); const ABI *abi = process->GetABI(); if (abi == NULL) return ret_plan_sp; Target *target = thread.CalculateTarget(); // FIXME: Since neither the value nor the Clang QualType know their ASTContext, // we have to make sure the type we put in our value list comes from the same ASTContext // the ABI will use to get the argument values. THis is the bottom-most frame's module. ClangASTContext *clang_ast_context = target->GetScratchClangASTContext(); ValueList argument_values; Value input_value; void *clang_void_ptr_type = clang_ast_context->GetVoidPtrType(false); input_value.SetValueType (Value::eValueTypeScalar); input_value.SetContext (Value::eContextTypeOpaqueClangQualType, clang_void_ptr_type); int obj_index; int sel_index; // If this is a struct return dispatch, then the first argument is the // return struct pointer, and the object is the second, and the selector is the third. // Otherwise the object is the first and the selector the second. if (this_dispatch->stret_return) { obj_index = 1; sel_index = 2; argument_values.PushValue(input_value); argument_values.PushValue(input_value); argument_values.PushValue(input_value); } else { obj_index = 0; sel_index = 1; argument_values.PushValue(input_value); argument_values.PushValue(input_value); } bool success = abi->GetArgumentValues (thread, argument_values); if (!success) return ret_plan_sp; // Okay, the first value here is the object, we actually want the class of that object. // For now we're just going with the ISA. // FIXME: This should really be the return value of [object class] to properly handle KVO interposition. Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); // This is a little cheesy, but since object->isa is the first field, // making the object value a load address value and resolving it will get // the pointer sized data pointed to by that value... ExecutionContext exec_ctx; thread.Calculate (exec_ctx); isa_value.SetValueType(Value::eValueTypeLoadAddress); isa_value.ResolveValue(&exec_ctx, clang_ast_context->getASTContext()); if (this_dispatch->fixedup == DispatchFunction::eFixUpFixed) { // For the FixedUp method the Selector is actually a pointer to a // structure, the second field of which is the selector number. Value *sel_value = argument_values.GetValueAtIndex(sel_index); sel_value->GetScalar() += process->GetAddressByteSize(); sel_value->SetValueType(Value::eValueTypeLoadAddress); sel_value->ResolveValue(&exec_ctx, clang_ast_context->getASTContext()); } else if (this_dispatch->fixedup == DispatchFunction::eFixUpToFix) { // FIXME: If the method dispatch is not "fixed up" then the selector is actually a // pointer to the string name of the selector. We need to look that up... // For now I'm going to punt on that and just return no plan. if (log) log->Printf ("Punting on stepping into un-fixed-up method dispatch."); return ret_plan_sp; } // FIXME: If this is a dispatch to the super-class, we need to get the super-class from // the class, and disaptch to that instead. // But for now I just punt and return no plan. if (this_dispatch->is_super) { if (log) log->Printf ("Punting on stepping into super method dispatch."); return ret_plan_sp; } ValueList dispatch_values; dispatch_values.PushValue (isa_value); dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index))); if (log) { log->Printf("Resolving method call for class - 0x%llx and selector - 0x%llx", dispatch_values.GetValueAtIndex(0)->GetScalar().ULongLong(), dispatch_values.GetValueAtIndex(1)->GetScalar().ULongLong()); } lldb::addr_t impl_addr = LookupInCache (dispatch_values.GetValueAtIndex(0)->GetScalar().ULongLong(), dispatch_values.GetValueAtIndex(1)->GetScalar().ULongLong()); if (impl_addr == LLDB_INVALID_ADDRESS) { Address resolve_address(NULL, this_dispatch->stret_return ? m_impl_stret_fn_addr : m_impl_fn_addr); StreamString errors; { // Scope for mutex locker: Mutex::Locker locker(m_impl_function_mutex); if (!m_impl_function.get()) { m_impl_function.reset(new ClangFunction(process->GetTargetTriple().GetCString(), clang_ast_context, clang_void_ptr_type, resolve_address, dispatch_values)); unsigned num_errors = m_impl_function->CompileFunction(errors); if (num_errors) { if (log) log->Printf ("Error compiling function: \"%s\".", errors.GetData()); return ret_plan_sp; } errors.Clear(); if (!m_impl_function->WriteFunctionWrapper(exec_ctx, errors)) { if (log) log->Printf ("Error Inserting function: \"%s\".", errors.GetData()); return ret_plan_sp; } } } errors.Clear(); // Now write down the argument values for this call. lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; if (!m_impl_function->WriteFunctionArguments (exec_ctx, args_addr, resolve_address, dispatch_values, errors)) return ret_plan_sp; ret_plan_sp.reset (new ThreadPlanStepThroughObjCTrampoline (thread, this, args_addr, argument_values.GetValueAtIndex(0)->GetScalar().ULongLong(), dispatch_values.GetValueAtIndex(0)->GetScalar().ULongLong(), dispatch_values.GetValueAtIndex(1)->GetScalar().ULongLong(), stop_others)); } else { if (log) log->Printf ("Found implementation address in cache: 0x%llx", impl_addr); ret_plan_sp.reset (new ThreadPlanRunToAddress (thread, impl_addr, stop_others)); } } return ret_plan_sp; } void ObjCTrampolineHandler::AddToCache (lldb::addr_t class_addr, lldb::addr_t selector, lldb::addr_t impl_addr) { Log *log = lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP); if (log) { log->Printf ("Caching: class 0x%llx selector 0x%llx implementation 0x%llx.", class_addr, selector, impl_addr); } m_impl_cache.insert (std::pair (ClassAndSel(class_addr, selector), impl_addr)); } lldb::addr_t ObjCTrampolineHandler::LookupInCache (lldb::addr_t class_addr, lldb::addr_t selector) { MsgImplMap::iterator pos, end = m_impl_cache.end(); pos = m_impl_cache.find (ClassAndSel(class_addr, selector)); if (pos != end) return (*pos).second; return LLDB_INVALID_ADDRESS; } ClangFunction * ObjCTrampolineHandler::GetLookupImplementationWrapperFunction () { return m_impl_function.get(); }