//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++ //-*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "AppleObjCTrampolineHandler.h" // C Includes // C++ Includes // Other libraries and framework includes // Project includes #include "AppleThreadPlanStepThroughObjCTrampoline.h" #include "lldb/Breakpoint/StoppointCallbackContext.h" #include "lldb/Core/Debugger.h" #include "lldb/Core/Module.h" #include "lldb/Core/StreamFile.h" #include "lldb/Core/Value.h" #include "lldb/Expression/DiagnosticManager.h" #include "lldb/Expression/FunctionCaller.h" #include "lldb/Expression/UserExpression.h" #include "lldb/Expression/UtilityFunction.h" #include "lldb/Symbol/ClangASTContext.h" #include "lldb/Symbol/Symbol.h" #include "lldb/Target/ABI.h" #include "lldb/Target/ExecutionContext.h" #include "lldb/Target/ObjCLanguageRuntime.h" #include "lldb/Target/Process.h" #include "lldb/Target/RegisterContext.h" #include "lldb/Target/Target.h" #include "lldb/Target/Thread.h" #include "lldb/Target/ThreadPlanRunToAddress.h" #include "lldb/Utility/ConstString.h" #include "lldb/Utility/FileSpec.h" #include "lldb/Utility/Log.h" #include "llvm/ADT/STLExtras.h" using namespace lldb; using namespace lldb_private; const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = "__lldb_objc_find_implementation_for_selector"; const char *AppleObjCTrampolineHandler:: g_lookup_implementation_with_stret_function_code = " \n\ extern \"C\" \n\ { \n\ extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ extern void *class_getMethodImplementation_stret(void *objc_class, void *sel); \n\ extern void * object_getClass (id object); \n\ extern void * sel_getUid(char *name); \n\ extern int printf(const char *format, ...); \n\ } \n\ extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ void *sel, \n\ int is_stret, \n\ int is_super, \n\ int is_super2, \n\ int is_fixup, \n\ int is_fixed, \n\ int debug) \n\ { \n\ struct __lldb_imp_return_struct \n\ { \n\ void *class_addr; \n\ void *sel_addr; \n\ void *impl_addr; \n\ }; \n\ \n\ struct __lldb_objc_class { \n\ void *isa; \n\ void *super_ptr; \n\ }; \n\ struct __lldb_objc_super { \n\ void *reciever; \n\ struct __lldb_objc_class *class_ptr; \n\ }; \n\ struct __lldb_msg_ref { \n\ void *dont_know; \n\ void *sel; \n\ }; \n\ \n\ struct __lldb_imp_return_struct return_struct; \n\ \n\ if (debug) \n\ printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ if (is_super) \n\ { \n\ if (is_super2) \n\ { \n\ return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ } \n\ else \n\ { \n\ return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ } \n\ } \n\ else \n\ { \n\ // This code seems a little funny, but has its reasons... \n\ // The call to [object class] is here because if this is a class, and has not been called into \n\ // yet, we need to do something to force the class to initialize itself. \n\ // Then the call to object_getClass will actually return the correct class, either the class \n\ // if object is a class instance, or the meta-class if it is a class pointer. \n\ void *class_ptr = (void *) [(id) object class]; \n\ return_struct.class_addr = (id) object_getClass((id) object); \n\ if (debug) \n\ { \n\ if (class_ptr == object) \n\ { \n\ printf (\"Found a class object, need to use the meta class %p -> %p\\n\", \n\ class_ptr, return_struct.class_addr); \n\ } \n\ else \n\ { \n\ printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ class_ptr, return_struct.class_addr); \n\ } \n\ } \n\ } \n\ \n\ if (is_fixup) \n\ { \n\ if (is_fixed) \n\ { \n\ return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ } \n\ else \n\ { \n\ char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ return_struct.sel_addr = sel_getUid (sel_name); \n\ if (debug) \n\ printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\", \n\ return_struct.sel_addr, sel_name); \n\ } \n\ } \n\ else \n\ { \n\ return_struct.sel_addr = sel; \n\ } \n\ \n\ if (is_stret) \n\ { \n\ return_struct.impl_addr = class_getMethodImplementation_stret (return_struct.class_addr, \n\ return_struct.sel_addr); \n\ } \n\ else \n\ { \n\ return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ return_struct.sel_addr); \n\ } \n\ if (debug) \n\ printf (\"\\n*** Returning implementation: %p.\\n\", return_struct.impl_addr); \n\ \n\ return return_struct.impl_addr; \n\ } \n\ "; const char * AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code = " \n\ extern \"C\" \n\ { \n\ extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ extern void * object_getClass (id object); \n\ extern void * sel_getUid(char *name); \n\ extern int printf(const char *format, ...); \n\ } \n\ extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ void *sel, \n\ int is_stret, \n\ int is_super, \n\ int is_super2, \n\ int is_fixup, \n\ int is_fixed, \n\ int debug) \n\ { \n\ struct __lldb_imp_return_struct \n\ { \n\ void *class_addr; \n\ void *sel_addr; \n\ void *impl_addr; \n\ }; \n\ \n\ struct __lldb_objc_class { \n\ void *isa; \n\ void *super_ptr; \n\ }; \n\ struct __lldb_objc_super { \n\ void *reciever; \n\ struct __lldb_objc_class *class_ptr; \n\ }; \n\ struct __lldb_msg_ref { \n\ void *dont_know; \n\ void *sel; \n\ }; \n\ \n\ struct __lldb_imp_return_struct return_struct; \n\ \n\ if (debug) \n\ printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ if (is_super) \n\ { \n\ if (is_super2) \n\ { \n\ return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ } \n\ else \n\ { \n\ return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ } \n\ } \n\ else \n\ { \n\ // This code seems a little funny, but has its reasons... \n\ // The call to [object class] is here because if this is a class, and has not been called into \n\ // yet, we need to do something to force the class to initialize itself. \n\ // Then the call to object_getClass will actually return the correct class, either the class \n\ // if object is a class instance, or the meta-class if it is a class pointer. \n\ void *class_ptr = (void *) [(id) object class]; \n\ return_struct.class_addr = (id) object_getClass((id) object); \n\ if (debug) \n\ { \n\ if (class_ptr == object) \n\ { \n\ printf (\"Found a class object, need to return the meta class %p -> %p\\n\", \n\ class_ptr, return_struct.class_addr); \n\ } \n\ else \n\ { \n\ printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ class_ptr, return_struct.class_addr); \n\ } \n\ } \n\ } \n\ \n\ if (is_fixup) \n\ { \n\ if (is_fixed) \n\ { \n\ return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ } \n\ else \n\ { \n\ char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ return_struct.sel_addr = sel_getUid (sel_name); \n\ if (debug) \n\ printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\", \n\ return_struct.sel_addr, sel_name); \n\ } \n\ } \n\ else \n\ { \n\ return_struct.sel_addr = sel; \n\ } \n\ \n\ return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ return_struct.sel_addr); \n\ if (debug) \n\ printf (\"\\n*** Returning implementation: 0x%p.\\n\", return_struct.impl_addr); \n\ \n\ return return_struct.impl_addr; \n\ } \n\ "; AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion( AppleObjCVTables *owner, lldb::addr_t header_addr) : m_valid(true), m_owner(owner), m_header_addr(header_addr), m_code_start_addr(0), m_code_end_addr(0), m_next_region(0) { SetUpRegion(); } AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() {} void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() { // The header looks like: // // uint16_t headerSize // uint16_t descSize // uint32_t descCount // void * next // // First read in the header: char memory_buffer[16]; ProcessSP process_sp = m_owner->GetProcessSP(); if (!process_sp) return; DataExtractor data(memory_buffer, sizeof(memory_buffer), process_sp->GetByteOrder(), process_sp->GetAddressByteSize()); size_t actual_size = 8 + process_sp->GetAddressByteSize(); Status error; size_t bytes_read = process_sp->ReadMemory(m_header_addr, memory_buffer, actual_size, error); if (bytes_read != actual_size) { m_valid = false; return; } lldb::offset_t offset = 0; const uint16_t header_size = data.GetU16(&offset); const uint16_t descriptor_size = data.GetU16(&offset); const size_t num_descriptors = data.GetU32(&offset); m_next_region = data.GetPointer(&offset); // If the header size is 0, that means we've come in too early before this // data is set up. // Set ourselves as not valid, and continue. if (header_size == 0 || num_descriptors == 0) { m_valid = false; return; } // Now read in all the descriptors: // The descriptor looks like: // // uint32_t offset // uint32_t flags // // Where offset is either 0 - in which case it is unused, or // it is the offset of the vtable code from the beginning of the descriptor // record. // Below, we'll convert that into an absolute code address, since I don't want // to have // to compute it over and over. // Ingest the whole descriptor array: const lldb::addr_t desc_ptr = m_header_addr + header_size; const size_t desc_array_size = num_descriptors * descriptor_size; DataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0')); uint8_t *dst = (uint8_t *)data_sp->GetBytes(); DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(), process_sp->GetAddressByteSize()); bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error); if (bytes_read != desc_array_size) { m_valid = false; return; } // The actual code for the vtables will be laid out consecutively, so I also // compute the start and end of the whole code block. offset = 0; m_code_start_addr = 0; m_code_end_addr = 0; for (size_t i = 0; i < num_descriptors; i++) { lldb::addr_t start_offset = offset; uint32_t voffset = desc_extractor.GetU32(&offset); uint32_t flags = desc_extractor.GetU32(&offset); lldb::addr_t code_addr = desc_ptr + start_offset + voffset; m_descriptors.push_back(VTableDescriptor(flags, code_addr)); if (m_code_start_addr == 0 || code_addr < m_code_start_addr) m_code_start_addr = code_addr; if (code_addr > m_code_end_addr) m_code_end_addr = code_addr; offset = start_offset + descriptor_size; } // Finally, a little bird told me that all the vtable code blocks are the same // size. // Let's compute the blocks and if they are all the same add the size to the // code end address: lldb::addr_t code_size = 0; bool all_the_same = true; for (size_t i = 0; i < num_descriptors - 1; i++) { lldb::addr_t this_size = m_descriptors[i + 1].code_start - m_descriptors[i].code_start; if (code_size == 0) code_size = this_size; else { if (this_size != code_size) all_the_same = false; if (this_size > code_size) code_size = this_size; } } if (all_the_same) m_code_end_addr += code_size; } bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion:: AddressInRegion(lldb::addr_t addr, uint32_t &flags) { if (!IsValid()) return false; if (addr < m_code_start_addr || addr > m_code_end_addr) return false; std::vector::iterator pos, end = m_descriptors.end(); for (pos = m_descriptors.begin(); pos != end; pos++) { if (addr <= (*pos).code_start) { flags = (*pos).flags; return true; } } return false; } void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump( Stream &s) { s.Printf("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n", m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); size_t num_elements = m_descriptors.size(); for (size_t i = 0; i < num_elements; i++) { s.Indent(); s.Printf("Code start: 0x%" PRIx64 " Flags: %d\n", m_descriptors[i].code_start, m_descriptors[i].flags); } } AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables( const ProcessSP &process_sp, const ModuleSP &objc_module_sp) : m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS), m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID), m_objc_module_sp(objc_module_sp) { if (process_sp) m_process_wp = process_sp; } AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() { ProcessSP process_sp = GetProcessSP(); if (process_sp) { if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) process_sp->GetTarget().RemoveBreakpointByID(m_trampolines_changed_bp_id); } } bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() { if (m_trampoline_header != LLDB_INVALID_ADDRESS) return true; ProcessSP process_sp = GetProcessSP(); if (process_sp) { Target &target = process_sp->GetTarget(); const ModuleList &target_modules = target.GetImages(); std::lock_guard guard(target_modules.GetMutex()); size_t num_modules = target_modules.GetSize(); if (!m_objc_module_sp) { for (size_t i = 0; i < num_modules; i++) { if (process_sp->GetObjCLanguageRuntime()->IsModuleObjCLibrary( target_modules.GetModuleAtIndexUnlocked(i))) { m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i); break; } } } if (m_objc_module_sp) { ConstString trampoline_name("gdb_objc_trampolines"); const Symbol *trampoline_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType(trampoline_name, eSymbolTypeData); if (trampoline_symbol != NULL) { m_trampoline_header = trampoline_symbol->GetLoadAddress(&target); if (m_trampoline_header == LLDB_INVALID_ADDRESS) return false; // Next look up the "changed" symbol and set a breakpoint on that... ConstString changed_name("gdb_objc_trampolines_changed"); const Symbol *changed_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType(changed_name, eSymbolTypeCode); if (changed_symbol != NULL) { const Address changed_symbol_addr = changed_symbol->GetAddress(); if (!changed_symbol_addr.IsValid()) return false; lldb::addr_t changed_addr = changed_symbol_addr.GetOpcodeLoadAddress(&target); if (changed_addr != LLDB_INVALID_ADDRESS) { BreakpointSP trampolines_changed_bp_sp = target.CreateBreakpoint(changed_addr, true, false); if (trampolines_changed_bp_sp) { m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); trampolines_changed_bp_sp->SetCallback(RefreshTrampolines, this, true); trampolines_changed_bp_sp->SetBreakpointKind( "objc-trampolines-changed"); return true; } } } } } } return false; } bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines( void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id, lldb::user_id_t break_loc_id) { AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton; if (vtable_handler->InitializeVTableSymbols()) { // The Update function is called with the address of an added region. So we // grab that address, and // feed it into ReadRegions. Of course, our friend the ABI will get the // values for us. ExecutionContext exe_ctx(context->exe_ctx_ref); Process *process = exe_ctx.GetProcessPtr(); const ABI *abi = process->GetABI().get(); ClangASTContext *clang_ast_context = process->GetTarget().GetScratchClangASTContext(); ValueList argument_values; Value input_value; CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); input_value.SetValueType(Value::eValueTypeScalar); // input_value.SetContext (Value::eContextTypeClangType, // clang_void_ptr_type); input_value.SetCompilerType(clang_void_ptr_type); argument_values.PushValue(input_value); bool success = abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values); if (!success) return false; // Now get a pointer value from the zeroth argument. Status error; DataExtractor data; error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data, 0, NULL); lldb::offset_t offset = 0; lldb::addr_t region_addr = data.GetPointer(&offset); if (region_addr != 0) vtable_handler->ReadRegions(region_addr); } return false; } bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() { // The no argument version reads the start region from the value of the // gdb_regions_header, and // gets started from there. m_regions.clear(); if (!InitializeVTableSymbols()) return false; Status error; ProcessSP process_sp = GetProcessSP(); if (process_sp) { lldb::addr_t region_addr = process_sp->ReadPointerFromMemory(m_trampoline_header, error); if (error.Success()) return ReadRegions(region_addr); } return false; } bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions( lldb::addr_t region_addr) { ProcessSP process_sp = GetProcessSP(); if (!process_sp) return false; Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); // We aren't starting at the trampoline symbol. InitializeVTableSymbols(); lldb::addr_t next_region = region_addr; // Read in the sizes of the headers. while (next_region != 0) { m_regions.push_back(VTableRegion(this, next_region)); if (!m_regions.back().IsValid()) { m_regions.clear(); return false; } if (log) { StreamString s; m_regions.back().Dump(s); log->Printf("Read vtable region: \n%s", s.GetData()); } next_region = m_regions.back().GetNextRegionAddr(); } return true; } bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables( lldb::addr_t addr, uint32_t &flags) { region_collection::iterator pos, end = m_regions.end(); for (pos = m_regions.begin(); pos != end; pos++) { if ((*pos).AddressInRegion(addr, flags)) return true; } return false; } const AppleObjCTrampolineHandler::DispatchFunction AppleObjCTrampolineHandler::g_dispatch_functions[] = { // NAME STRET SUPER SUPER2 FIXUP TYPE {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone}, {"objc_msgSend_fixup", false, false, false, DispatchFunction::eFixUpToFix}, {"objc_msgSend_fixedup", false, false, false, DispatchFunction::eFixUpFixed}, {"objc_msgSend_stret", true, false, false, DispatchFunction::eFixUpNone}, {"objc_msgSend_stret_fixup", true, false, false, DispatchFunction::eFixUpToFix}, {"objc_msgSend_stret_fixedup", true, false, false, DispatchFunction::eFixUpFixed}, {"objc_msgSend_fpret", false, false, false, DispatchFunction::eFixUpNone}, {"objc_msgSend_fpret_fixup", false, false, false, DispatchFunction::eFixUpToFix}, {"objc_msgSend_fpret_fixedup", false, false, false, DispatchFunction::eFixUpFixed}, {"objc_msgSend_fp2ret", false, false, true, DispatchFunction::eFixUpNone}, {"objc_msgSend_fp2ret_fixup", false, false, true, DispatchFunction::eFixUpToFix}, {"objc_msgSend_fp2ret_fixedup", false, false, true, DispatchFunction::eFixUpFixed}, {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone}, {"objc_msgSendSuper_stret", true, true, false, DispatchFunction::eFixUpNone}, {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone}, {"objc_msgSendSuper2_fixup", false, true, true, DispatchFunction::eFixUpToFix}, {"objc_msgSendSuper2_fixedup", false, true, true, DispatchFunction::eFixUpFixed}, {"objc_msgSendSuper2_stret", true, true, true, DispatchFunction::eFixUpNone}, {"objc_msgSendSuper2_stret_fixup", true, true, true, DispatchFunction::eFixUpToFix}, {"objc_msgSendSuper2_stret_fixedup", true, true, true, DispatchFunction::eFixUpFixed}, }; AppleObjCTrampolineHandler::AppleObjCTrampolineHandler( const ProcessSP &process_sp, const ModuleSP &objc_module_sp) : m_process_wp(), m_objc_module_sp(objc_module_sp), m_lookup_implementation_function_code(nullptr), m_impl_fn_addr(LLDB_INVALID_ADDRESS), m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS), m_msg_forward_addr(LLDB_INVALID_ADDRESS) { if (process_sp) m_process_wp = process_sp; // Look up the known resolution functions: ConstString get_impl_name("class_getMethodImplementation"); ConstString get_impl_stret_name("class_getMethodImplementation_stret"); ConstString msg_forward_name("_objc_msgForward"); ConstString msg_forward_stret_name("_objc_msgForward_stret"); Target *target = process_sp ? &process_sp->GetTarget() : NULL; 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); const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType( msg_forward_name, eSymbolTypeCode); const Symbol *msg_forward_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType(msg_forward_stret_name, eSymbolTypeCode); if (class_getMethodImplementation) m_impl_fn_addr = class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress( target); if (class_getMethodImplementation_stret) m_impl_stret_fn_addr = class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress( target); if (msg_forward) m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target); if (msg_forward_stret) m_msg_forward_stret_addr = msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target); // FIXME: Do some kind of logging here. if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) { // If we can't even find the ordinary get method implementation function, // then we aren't going to be able to // step through any method dispatches. Warn to that effect and get out of // here. if (process_sp->CanJIT()) { process_sp->GetTarget().GetDebugger().GetErrorFile()->Printf( "Could not find implementation lookup function \"%s\"" " step in through ObjC method dispatch will not work.\n", get_impl_name.AsCString()); } return; } else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) { // It there is no stret return lookup function, assume that it is the same // as the straight lookup: m_impl_stret_fn_addr = m_impl_fn_addr; // Also we will use the version of the lookup code that doesn't rely on the // stret version of the function. m_lookup_implementation_function_code = g_lookup_implementation_no_stret_function_code; } else { m_lookup_implementation_function_code = g_lookup_implementation_with_stret_function_code; } // 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 (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); 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 && msgSend_symbol->ValueIsAddress()) { // FixMe: Make g_dispatch_functions static table of DispatchFunctions, 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->GetAddressRef().GetOpcodeLoadAddress(target); m_msgSend_map.insert(std::pair(sym_addr, i)); } } // Build our vtable dispatch handler here: m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); if (m_vtables_ap.get()) m_vtables_ap->ReadRegions(); } lldb::addr_t AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread, ValueList &dispatch_values) { ThreadSP thread_sp(thread.shared_from_this()); ExecutionContext exe_ctx(thread_sp); DiagnosticManager diagnostics; Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; FunctionCaller *impl_function_caller = nullptr; // Scope for mutex locker: { std::lock_guard guard(m_impl_function_mutex); // First stage is to make the ClangUtility to hold our injected function: if (!m_impl_code.get()) { if (m_lookup_implementation_function_code != NULL) { Status error; m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage( m_lookup_implementation_function_code, eLanguageTypeObjC, g_lookup_implementation_function_name, error)); if (error.Fail()) { if (log) log->Printf( "Failed to get Utility Function for implementation lookup: %s.", error.AsCString()); m_impl_code.reset(); return args_addr; } if (!m_impl_code->Install(diagnostics, exe_ctx)) { if (log) { log->Printf("Failed to install implementation lookup."); diagnostics.Dump(log); } m_impl_code.reset(); return args_addr; } } else { if (log) log->Printf("No method lookup implementation code."); return LLDB_INVALID_ADDRESS; } // Next make the runner function for our implementation utility function. ClangASTContext *clang_ast_context = thread.GetProcess()->GetTarget().GetScratchClangASTContext(); CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); Status error; impl_function_caller = m_impl_code->MakeFunctionCaller( clang_void_ptr_type, dispatch_values, thread_sp, error); if (error.Fail()) { if (log) log->Printf( "Error getting function caller for dispatch lookup: \"%s\".", error.AsCString()); return args_addr; } } else { impl_function_caller = m_impl_code->GetFunctionCaller(); } } diagnostics.Clear(); // Now write down the argument values for this particular call. This looks // like it might be a race condition // if other threads were calling into here, but actually it isn't because we // allocate a new args structure for // this call by passing args_addr = LLDB_INVALID_ADDRESS... if (!impl_function_caller->WriteFunctionArguments( exe_ctx, args_addr, dispatch_values, diagnostics)) { if (log) { log->Printf("Error writing function arguments."); diagnostics.Dump(log); } return args_addr; } return args_addr; } ThreadPlanSP AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread, bool stop_others) { ThreadPlanSP ret_plan_sp; lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); DispatchFunction this_dispatch; bool found_it = false; // First step is to look and see if we are in one of the known ObjC dispatch // functions. We've already compiled // a table of same, so consult it. MsgsendMap::iterator pos; pos = m_msgSend_map.find(curr_pc); if (pos != m_msgSend_map.end()) { this_dispatch = g_dispatch_functions[(*pos).second]; found_it = true; } // Next check to see if we are in a vtable region: if (!found_it) { uint32_t flags; if (m_vtables_ap.get()) { found_it = m_vtables_ap->IsAddressInVTables(curr_pc, flags); if (found_it) { this_dispatch.name = "vtable"; this_dispatch.stret_return = (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; this_dispatch.is_super = false; this_dispatch.is_super2 = false; this_dispatch.fixedup = DispatchFunction::eFixUpFixed; } } } if (found_it) { Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); // We are decoding a method dispatch. // First job is to pull the arguments out: lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); const ABI *abi = NULL; ProcessSP process_sp(thread.CalculateProcess()); if (process_sp) abi = process_sp->GetABI().get(); if (abi == NULL) return ret_plan_sp; TargetSP target_sp(thread.CalculateTarget()); ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext(); ValueList argument_values; Value void_ptr_value; CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); void_ptr_value.SetValueType(Value::eValueTypeScalar); // void_ptr_value.SetContext (Value::eContextTypeClangType, // clang_void_ptr_type); void_ptr_value.SetCompilerType(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(void_ptr_value); argument_values.PushValue(void_ptr_value); argument_values.PushValue(void_ptr_value); } else { obj_index = 0; sel_index = 1; argument_values.PushValue(void_ptr_value); argument_values.PushValue(void_ptr_value); } bool success = abi->GetArgumentValues(thread, argument_values); if (!success) return ret_plan_sp; lldb::addr_t obj_addr = argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong(); if (obj_addr == 0x0) { if (log) log->Printf( "Asked to step to dispatch to nil object, returning empty plan."); return ret_plan_sp; } ExecutionContext exe_ctx(thread.shared_from_this()); Process *process = exe_ctx.GetProcessPtr(); // isa_addr will store the class pointer that the method is being dispatched // to - so either the class // directly or the super class if this is one of the objc_msgSendSuper // flavors. That's mostly used to // look up the class/selector pair in our cache. lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; lldb::addr_t sel_addr = argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); // Figure out the class this is being dispatched to and see if we've already // cached this method call, // If so we can push a run-to-address plan directly. Otherwise we have to // figure out where // the implementation lives. if (this_dispatch.is_super) { if (this_dispatch.is_super2) { // In the objc_msgSendSuper2 case, we don't get the object directly, we // get a structure containing // the object and the class to which the super message is being sent. // So we need to dig the super // out of the class and use that. Value super_value(*(argument_values.GetValueAtIndex(obj_index))); super_value.GetScalar() += process->GetAddressByteSize(); super_value.ResolveValue(&exe_ctx); if (super_value.GetScalar().IsValid()) { // isa_value now holds the class pointer. The second word of the // class pointer is the super-class pointer: super_value.GetScalar() += process->GetAddressByteSize(); super_value.ResolveValue(&exe_ctx); if (super_value.GetScalar().IsValid()) isa_addr = super_value.GetScalar().ULongLong(); else { if (log) log->Printf("Failed to extract the super class value from the " "class in objc_super."); } } else { if (log) log->Printf("Failed to extract the class value from objc_super."); } } else { // In the objc_msgSendSuper case, we don't get the object directly, we // get a two element structure containing // the object and the super class to which the super message is being // sent. So the class we want is // the second element of this structure. Value super_value(*(argument_values.GetValueAtIndex(obj_index))); super_value.GetScalar() += process->GetAddressByteSize(); super_value.ResolveValue(&exe_ctx); if (super_value.GetScalar().IsValid()) { isa_addr = super_value.GetScalar().ULongLong(); } else { if (log) log->Printf("Failed to extract the class value from objc_super."); } } } else { // In the direct dispatch case, the object->isa is the class pointer we // want. // 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... // Note, it isn't a fatal error not to be able to get the address from the // object, since this might // be a "tagged pointer" which isn't a real object, but rather some word // length encoded dingus. Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); isa_value.SetValueType(Value::eValueTypeLoadAddress); isa_value.ResolveValue(&exe_ctx); if (isa_value.GetScalar().IsValid()) { isa_addr = isa_value.GetScalar().ULongLong(); } else { if (log) log->Printf("Failed to extract the isa value from object."); } } // Okay, we've got the address of the class for which we're resolving this, // let's see if it's in our cache: lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; if (isa_addr != LLDB_INVALID_ADDRESS) { if (log) { log->Printf("Resolving call for class - 0x%" PRIx64 " and selector - 0x%" PRIx64, isa_addr, sel_addr); } ObjCLanguageRuntime *objc_runtime = thread.GetProcess()->GetObjCLanguageRuntime(); assert(objc_runtime != NULL); impl_addr = objc_runtime->LookupInMethodCache(isa_addr, sel_addr); } if (impl_addr != LLDB_INVALID_ADDRESS) { // Yup, it was in the cache, so we can run to that address directly. if (log) log->Printf("Found implementation address in cache: 0x%" PRIx64, impl_addr); ret_plan_sp.reset( new ThreadPlanRunToAddress(thread, impl_addr, stop_others)); } else { // We haven't seen this class/selector pair yet. Look it up. StreamString errors; Address impl_code_address; ValueList dispatch_values; // We've will inject a little function in the target that takes the // object, selector and some flags, // and figures out the implementation. Looks like: // void *__lldb_objc_find_implementation_for_selector (void *object, // void *sel, // int is_stret, // int is_super, // int is_super2, // int is_fixup, // int is_fixed, // int debug) // So set up the arguments for that call. dispatch_values.PushValue(*(argument_values.GetValueAtIndex(obj_index))); dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index))); Value flag_value; CompilerType clang_int_type = clang_ast_context->GetBuiltinTypeForEncodingAndBitSize( lldb::eEncodingSint, 32); flag_value.SetValueType(Value::eValueTypeScalar); // flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); flag_value.SetCompilerType(clang_int_type); if (this_dispatch.stret_return) flag_value.GetScalar() = 1; else flag_value.GetScalar() = 0; dispatch_values.PushValue(flag_value); if (this_dispatch.is_super) flag_value.GetScalar() = 1; else flag_value.GetScalar() = 0; dispatch_values.PushValue(flag_value); if (this_dispatch.is_super2) flag_value.GetScalar() = 1; else flag_value.GetScalar() = 0; dispatch_values.PushValue(flag_value); switch (this_dispatch.fixedup) { case DispatchFunction::eFixUpNone: flag_value.GetScalar() = 0; dispatch_values.PushValue(flag_value); dispatch_values.PushValue(flag_value); break; case DispatchFunction::eFixUpFixed: flag_value.GetScalar() = 1; dispatch_values.PushValue(flag_value); flag_value.GetScalar() = 1; dispatch_values.PushValue(flag_value); break; case DispatchFunction::eFixUpToFix: flag_value.GetScalar() = 1; dispatch_values.PushValue(flag_value); flag_value.GetScalar() = 0; dispatch_values.PushValue(flag_value); break; } if (log && log->GetVerbose()) flag_value.GetScalar() = 1; else flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. dispatch_values.PushValue(flag_value); // The step through code might have to fill in the cache, so it is not // safe to run only one thread. // So we override the stop_others value passed in to us here: const bool trampoline_stop_others = false; ret_plan_sp.reset(new AppleThreadPlanStepThroughObjCTrampoline( thread, this, dispatch_values, isa_addr, sel_addr, trampoline_stop_others)); if (log) { StreamString s; ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); log->Printf("Using ObjC step plan: %s.\n", s.GetData()); } } } return ret_plan_sp; } FunctionCaller * AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() { return m_impl_code->GetFunctionCaller(); }