1 //===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "AppleObjCTrampolineHandler.h" 11 12 // C Includes 13 // C++ Includes 14 // Other libraries and framework includes 15 // Project includes 16 #include "AppleThreadPlanStepThroughObjCTrampoline.h" 17 18 #include "lldb/Breakpoint/StoppointCallbackContext.h" 19 #include "lldb/Core/ConstString.h" 20 #include "lldb/Core/Debugger.h" 21 #include "lldb/Host/FileSpec.h" 22 #include "lldb/Core/Log.h" 23 #include "lldb/Core/Module.h" 24 #include "lldb/Core/Value.h" 25 #include "lldb/Expression/ClangExpression.h" 26 #include "lldb/Expression/ClangFunction.h" 27 #include "lldb/Expression/ClangUtilityFunction.h" 28 29 #include "lldb/Symbol/ClangASTContext.h" 30 #include "lldb/Target/ObjCLanguageRuntime.h" 31 #include "lldb/Target/Process.h" 32 #include "lldb/Target/RegisterContext.h" 33 #include "lldb/Target/Target.h" 34 #include "lldb/Target/Thread.h" 35 #include "lldb/Target/ExecutionContext.h" 36 #include "lldb/Target/ThreadPlanRunToAddress.h" 37 38 using namespace lldb; 39 using namespace lldb_private; 40 41 const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = "__lldb_objc_find_implementation_for_selector"; 42 const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_code = " \n\ 43 extern \"C\" \n\ 44 { \n\ 45 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 46 extern void *class_getMethodImplementation_stret(void *objc_class, void *sel); \n\ 47 extern void * sel_getUid(char *name); \n\ 48 extern int printf(const char *format, ...); \n\ 49 } \n\ 50 extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ 51 void *sel, \n\ 52 int is_stret, \n\ 53 int is_super, \n\ 54 int is_super2, \n\ 55 int is_fixup, \n\ 56 int is_fixed, \n\ 57 int debug) \n\ 58 { \n\ 59 struct __lldb_imp_return_struct \n\ 60 { \n\ 61 void *class_addr; \n\ 62 void *sel_addr; \n\ 63 void *impl_addr; \n\ 64 }; \n\ 65 \n\ 66 struct __lldb_objc_class { \n\ 67 void *isa; \n\ 68 void *super_ptr; \n\ 69 }; \n\ 70 struct __lldb_objc_super { \n\ 71 void *reciever; \n\ 72 struct __lldb_objc_class *class_ptr; \n\ 73 }; \n\ 74 struct __lldb_msg_ref { \n\ 75 void *dont_know; \n\ 76 void *sel; \n\ 77 }; \n\ 78 \n\ 79 struct __lldb_imp_return_struct return_struct; \n\ 80 \n\ 81 if (debug) \n\ 82 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ 83 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 84 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ 85 if (is_super) \n\ 86 { \n\ 87 if (is_super2) \n\ 88 { \n\ 89 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ 90 } \n\ 91 else \n\ 92 { \n\ 93 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ 94 } \n\ 95 } \n\ 96 else \n\ 97 { \n\ 98 void *class_ptr = (void *) [(id) object class]; \n\ 99 if (class_ptr == object) \n\ 100 { \n\ 101 struct __lldb_objc_class *class_as_class_struct = (struct __lldb_objc_class *) class_ptr; \n\ 102 if (debug) \n\ 103 printf (\"Found a class object, need to return the meta class 0x%p -> 0x%p\\n\", \n\ 104 class_ptr, class_as_class_struct->isa); \n\ 105 return_struct.class_addr = class_as_class_struct->isa; \n\ 106 } \n\ 107 else \n\ 108 { \n\ 109 if (debug) \n\ 110 printf (\"[object class] returned: 0x%p.\\n\", class_ptr); \n\ 111 return_struct.class_addr = class_ptr; \n\ 112 } \n\ 113 } \n\ 114 \n\ 115 if (is_fixup) \n\ 116 { \n\ 117 if (is_fixed) \n\ 118 { \n\ 119 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 120 } \n\ 121 else \n\ 122 { \n\ 123 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 124 return_struct.sel_addr = sel_getUid (sel_name); \n\ 125 if (debug) \n\ 126 printf (\"\\n*** Got fixed up selector: 0x%p for name %s.\\n\", \n\ 127 return_struct.sel_addr, sel_name); \n\ 128 } \n\ 129 } \n\ 130 else \n\ 131 { \n\ 132 return_struct.sel_addr = sel; \n\ 133 } \n\ 134 \n\ 135 if (is_stret) \n\ 136 { \n\ 137 return_struct.impl_addr = class_getMethodImplementation_stret (return_struct.class_addr, \n\ 138 return_struct.sel_addr); \n\ 139 } \n\ 140 else \n\ 141 { \n\ 142 return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ 143 return_struct.sel_addr); \n\ 144 } \n\ 145 if (debug) \n\ 146 printf (\"\\n*** Returning implementation: 0x%p.\\n\", return_struct.impl_addr); \n\ 147 \n\ 148 return return_struct.impl_addr; \n\ 149 } \n\ 150 "; 151 152 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion(AppleObjCVTables *owner, lldb::addr_t header_addr) : 153 m_valid (true), 154 m_owner(owner), 155 m_header_addr (header_addr), 156 m_code_start_addr(0), 157 m_code_end_addr (0), 158 m_next_region (0) 159 { 160 SetUpRegion (); 161 } 162 163 AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() 164 { 165 } 166 167 void 168 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() 169 { 170 // The header looks like: 171 // 172 // uint16_t headerSize 173 // uint16_t descSize 174 // uint32_t descCount 175 // void * next 176 // 177 // First read in the header: 178 179 char memory_buffer[16]; 180 Process *process = m_owner->GetProcess(); 181 DataExtractor data(memory_buffer, sizeof(memory_buffer), 182 process->GetByteOrder(), 183 process->GetAddressByteSize()); 184 size_t actual_size = 8 + process->GetAddressByteSize(); 185 Error error; 186 size_t bytes_read = process->ReadMemory (m_header_addr, memory_buffer, actual_size, error); 187 if (bytes_read != actual_size) 188 { 189 m_valid = false; 190 return; 191 } 192 193 uint32_t offset_ptr = 0; 194 const uint16_t header_size = data.GetU16(&offset_ptr); 195 const uint16_t descriptor_size = data.GetU16(&offset_ptr); 196 const size_t num_descriptors = data.GetU32(&offset_ptr); 197 198 m_next_region = data.GetPointer(&offset_ptr); 199 200 // If the header size is 0, that means we've come in too early before this data is set up. 201 // Set ourselves as not valid, and continue. 202 if (header_size == 0 || num_descriptors == 0) 203 { 204 m_valid = false; 205 return; 206 } 207 208 // Now read in all the descriptors: 209 // The descriptor looks like: 210 // 211 // uint32_t offset 212 // uint32_t flags 213 // 214 // Where offset is either 0 - in which case it is unused, or 215 // it is the offset of the vtable code from the beginning of the descriptor record. 216 // Below, we'll convert that into an absolute code address, since I don't want to have 217 // to compute it over and over. 218 219 // Ingest the whole descriptor array: 220 const lldb::addr_t desc_ptr = m_header_addr + header_size; 221 const size_t desc_array_size = num_descriptors * descriptor_size; 222 DataBufferSP data_sp(new DataBufferHeap (desc_array_size, '\0')); 223 uint8_t* dst = (uint8_t*)data_sp->GetBytes(); 224 225 DataExtractor desc_extractor (dst, desc_array_size, 226 process->GetByteOrder(), 227 process->GetAddressByteSize()); 228 bytes_read = process->ReadMemory(desc_ptr, dst, desc_array_size, error); 229 if (bytes_read != desc_array_size) 230 { 231 m_valid = false; 232 return; 233 } 234 235 // The actual code for the vtables will be laid out consecutively, so I also 236 // compute the start and end of the whole code block. 237 238 offset_ptr = 0; 239 m_code_start_addr = 0; 240 m_code_end_addr = 0; 241 242 for (int i = 0; i < num_descriptors; i++) 243 { 244 lldb::addr_t start_offset = offset_ptr; 245 uint32_t offset = desc_extractor.GetU32 (&offset_ptr); 246 uint32_t flags = desc_extractor.GetU32 (&offset_ptr); 247 lldb:addr_t code_addr = desc_ptr + start_offset + offset; 248 m_descriptors.push_back (VTableDescriptor(flags, code_addr)); 249 250 if (m_code_start_addr == 0 || code_addr < m_code_start_addr) 251 m_code_start_addr = code_addr; 252 if (code_addr > m_code_end_addr) 253 m_code_end_addr = code_addr; 254 255 offset_ptr = start_offset + descriptor_size; 256 } 257 // Finally, a little bird told me that all the vtable code blocks are the same size. 258 // Let's compute the blocks and if they are all the same add the size to the code end address: 259 lldb::addr_t code_size = 0; 260 bool all_the_same = true; 261 for (int i = 0; i < num_descriptors - 1; i++) 262 { 263 lldb::addr_t this_size = m_descriptors[i + 1].code_start - m_descriptors[i].code_start; 264 if (code_size == 0) 265 code_size = this_size; 266 else 267 { 268 if (this_size != code_size) 269 all_the_same = false; 270 if (this_size > code_size) 271 code_size = this_size; 272 } 273 } 274 if (all_the_same) 275 m_code_end_addr += code_size; 276 } 277 278 bool 279 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::AddressInRegion (lldb::addr_t addr, uint32_t &flags) 280 { 281 if (!IsValid()) 282 return false; 283 284 if (addr < m_code_start_addr || addr > m_code_end_addr) 285 return false; 286 287 std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end(); 288 for (pos = m_descriptors.begin(); pos != end; pos++) 289 { 290 if (addr <= (*pos).code_start) 291 { 292 flags = (*pos).flags; 293 return true; 294 } 295 } 296 return false; 297 } 298 299 void 300 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump (Stream &s) 301 { 302 s.Printf ("Header addr: 0x%llx Code start: 0x%llx Code End: 0x%llx Next: 0x%llx\n", 303 m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); 304 size_t num_elements = m_descriptors.size(); 305 for (size_t i = 0; i < num_elements; i++) 306 { 307 s.Indent(); 308 s.Printf ("Code start: 0x%llx Flags: %d\n", m_descriptors[i].code_start, m_descriptors[i].flags); 309 } 310 } 311 312 AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables (const ProcessSP &process_sp, 313 const ModuleSP &objc_module_sp) : 314 m_process_sp (process_sp), 315 m_trampoline_header (LLDB_INVALID_ADDRESS), 316 m_trampolines_changed_bp_id (LLDB_INVALID_BREAK_ID), 317 m_objc_module_sp (objc_module_sp) 318 { 319 320 } 321 322 AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() 323 { 324 if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) 325 m_process_sp->GetTarget().RemoveBreakpointByID (m_trampolines_changed_bp_id); 326 } 327 328 bool 329 AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols () 330 { 331 if (m_trampoline_header != LLDB_INVALID_ADDRESS) 332 return true; 333 Target &target = m_process_sp->GetTarget(); 334 335 ModuleList &modules = target.GetImages(); 336 size_t num_modules = modules.GetSize(); 337 if (!m_objc_module_sp) 338 { 339 for (size_t i = 0; i < num_modules; i++) 340 { 341 if (m_process_sp->GetObjCLanguageRuntime()->IsModuleObjCLibrary (modules.GetModuleAtIndex(i))) 342 { 343 m_objc_module_sp = modules.GetModuleAtIndex(i); 344 break; 345 } 346 } 347 } 348 349 if (m_objc_module_sp) 350 { 351 ConstString trampoline_name ("gdb_objc_trampolines"); 352 const Symbol *trampoline_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (trampoline_name, 353 eSymbolTypeData); 354 if (trampoline_symbol != NULL) 355 { 356 if (!trampoline_symbol->GetValue().IsValid()) 357 return false; 358 359 m_trampoline_header = trampoline_symbol->GetValue().GetLoadAddress(&target); 360 if (m_trampoline_header == LLDB_INVALID_ADDRESS) 361 return false; 362 363 // Next look up the "changed" symbol and set a breakpoint on that... 364 ConstString changed_name ("gdb_objc_trampolines_changed"); 365 const Symbol *changed_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (changed_name, 366 eSymbolTypeCode); 367 if (changed_symbol != NULL) 368 { 369 if (!changed_symbol->GetValue().IsValid()) 370 return false; 371 372 lldb::addr_t changed_addr = changed_symbol->GetValue().GetOpcodeLoadAddress (&target); 373 if (changed_addr != LLDB_INVALID_ADDRESS) 374 { 375 BreakpointSP trampolines_changed_bp_sp = target.CreateBreakpoint (changed_addr, true); 376 if (trampolines_changed_bp_sp) 377 { 378 m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); 379 trampolines_changed_bp_sp->SetCallback (RefreshTrampolines, this, true); 380 return true; 381 } 382 } 383 } 384 } 385 } 386 387 return false; 388 } 389 390 bool 391 AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines (void *baton, 392 StoppointCallbackContext *context, 393 lldb::user_id_t break_id, 394 lldb::user_id_t break_loc_id) 395 { 396 AppleObjCVTables *vtable_handler = (AppleObjCVTables *) baton; 397 if (vtable_handler->InitializeVTableSymbols()) 398 { 399 // The Update function is called with the address of an added region. So we grab that address, and 400 // feed it into ReadRegions. Of course, our friend the ABI will get the values for us. 401 Process *process = context->exe_ctx.GetProcessPtr(); 402 const ABI *abi = process->GetABI().get(); 403 404 ClangASTContext *clang_ast_context = process->GetTarget().GetScratchClangASTContext(); 405 ValueList argument_values; 406 Value input_value; 407 void *clang_void_ptr_type = clang_ast_context->GetVoidPtrType(false); 408 input_value.SetValueType (Value::eValueTypeScalar); 409 input_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type); 410 argument_values.PushValue(input_value); 411 412 bool success = abi->GetArgumentValues (context->exe_ctx.GetThreadRef(), argument_values); 413 if (!success) 414 return false; 415 416 // Now get a pointer value from the zeroth argument. 417 Error error; 418 DataExtractor data; 419 error = argument_values.GetValueAtIndex(0)->GetValueAsData (&(context->exe_ctx), 420 clang_ast_context->getASTContext(), 421 data, 422 0, 423 NULL); 424 uint32_t offset_ptr = 0; 425 lldb::addr_t region_addr = data.GetPointer(&offset_ptr); 426 427 if (region_addr != 0) 428 vtable_handler->ReadRegions(region_addr); 429 } 430 return false; 431 } 432 433 bool 434 AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions () 435 { 436 // The no argument version reads the start region from the value of the gdb_regions_header, and 437 // gets started from there. 438 439 m_regions.clear(); 440 if (!InitializeVTableSymbols()) 441 return false; 442 Error error; 443 lldb::addr_t region_addr = m_process_sp->ReadPointerFromMemory (m_trampoline_header, error); 444 if (error.Success()) 445 return ReadRegions (region_addr); 446 return false; 447 } 448 449 bool 450 AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions (lldb::addr_t region_addr) 451 { 452 if (!m_process_sp) 453 return false; 454 455 LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); 456 457 // We aren't starting at the trampoline symbol. 458 InitializeVTableSymbols (); 459 lldb::addr_t next_region = region_addr; 460 461 // Read in the sizes of the headers. 462 while (next_region != 0) 463 { 464 m_regions.push_back (VTableRegion(this, next_region)); 465 if (!m_regions.back().IsValid()) 466 { 467 m_regions.clear(); 468 return false; 469 } 470 if (log) 471 { 472 StreamString s; 473 m_regions.back().Dump(s); 474 log->Printf("Read vtable region: \n%s", s.GetData()); 475 } 476 477 next_region = m_regions.back().GetNextRegionAddr(); 478 } 479 480 return true; 481 } 482 483 bool 484 AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables (lldb::addr_t addr, uint32_t &flags) 485 { 486 region_collection::iterator pos, end = m_regions.end(); 487 for (pos = m_regions.begin(); pos != end; pos++) 488 { 489 if ((*pos).AddressInRegion (addr, flags)) 490 return true; 491 } 492 return false; 493 } 494 495 const AppleObjCTrampolineHandler::DispatchFunction 496 AppleObjCTrampolineHandler::g_dispatch_functions[] = 497 { 498 // NAME STRET SUPER SUPER2 FIXUP TYPE 499 {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone }, 500 {"objc_msgSend_fixup", false, false, false, DispatchFunction::eFixUpToFix }, 501 {"objc_msgSend_fixedup", false, false, false, DispatchFunction::eFixUpFixed }, 502 {"objc_msgSend_stret", true, false, false, DispatchFunction::eFixUpNone }, 503 {"objc_msgSend_stret_fixup", true, false, false, DispatchFunction::eFixUpToFix }, 504 {"objc_msgSend_stret_fixedup", true, false, false, DispatchFunction::eFixUpFixed }, 505 {"objc_msgSend_fpret", false, false, false, DispatchFunction::eFixUpNone }, 506 {"objc_msgSend_fpret_fixup", false, false, false, DispatchFunction::eFixUpToFix }, 507 {"objc_msgSend_fpret_fixedup", false, false, false, DispatchFunction::eFixUpFixed }, 508 {"objc_msgSend_fp2ret", false, false, true, DispatchFunction::eFixUpNone }, 509 {"objc_msgSend_fp2ret_fixup", false, false, true, DispatchFunction::eFixUpToFix }, 510 {"objc_msgSend_fp2ret_fixedup", false, false, true, DispatchFunction::eFixUpFixed }, 511 {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone }, 512 {"objc_msgSendSuper_stret", true, true, false, DispatchFunction::eFixUpNone }, 513 {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone }, 514 {"objc_msgSendSuper2_fixup", false, true, true, DispatchFunction::eFixUpToFix }, 515 {"objc_msgSendSuper2_fixedup", false, true, true, DispatchFunction::eFixUpFixed }, 516 {"objc_msgSendSuper2_stret", true, true, true, DispatchFunction::eFixUpNone }, 517 {"objc_msgSendSuper2_stret_fixup", true, true, true, DispatchFunction::eFixUpToFix }, 518 {"objc_msgSendSuper2_stret_fixedup", true, true, true, DispatchFunction::eFixUpFixed }, 519 {NULL} 520 }; 521 522 AppleObjCTrampolineHandler::AppleObjCTrampolineHandler (const ProcessSP &process_sp, 523 const ModuleSP &objc_module_sp) : 524 m_process_sp (process_sp), 525 m_objc_module_sp (objc_module_sp), 526 m_impl_fn_addr (LLDB_INVALID_ADDRESS), 527 m_impl_stret_fn_addr (LLDB_INVALID_ADDRESS), 528 m_msg_forward_addr (LLDB_INVALID_ADDRESS) 529 { 530 // Look up the known resolution functions: 531 532 ConstString get_impl_name("class_getMethodImplementation"); 533 ConstString get_impl_stret_name("class_getMethodImplementation_stret"); 534 ConstString msg_forward_name("_objc_msgForward"); 535 ConstString msg_forward_stret_name("_objc_msgForward_stret"); 536 537 Target *target = m_process_sp ? &m_process_sp->GetTarget() : NULL; 538 const Symbol *class_getMethodImplementation = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_name, eSymbolTypeCode); 539 const Symbol *class_getMethodImplementation_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_stret_name, eSymbolTypeCode); 540 const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType (msg_forward_name, eSymbolTypeCode); 541 const Symbol *msg_forward_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (msg_forward_stret_name, eSymbolTypeCode); 542 543 if (class_getMethodImplementation) 544 m_impl_fn_addr = class_getMethodImplementation->GetValue().GetOpcodeLoadAddress (target); 545 if (class_getMethodImplementation_stret) 546 m_impl_stret_fn_addr = class_getMethodImplementation_stret->GetValue().GetOpcodeLoadAddress (target); 547 if (msg_forward) 548 m_msg_forward_addr = msg_forward->GetValue().GetOpcodeLoadAddress(target); 549 if (msg_forward_stret) 550 m_msg_forward_stret_addr = msg_forward_stret->GetValue().GetOpcodeLoadAddress(target); 551 552 // FIXME: Do some kind of logging here. 553 if (m_impl_fn_addr == LLDB_INVALID_ADDRESS || m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) 554 return; 555 556 // Look up the addresses for the objc dispatch functions and cache them. For now I'm inspecting the symbol 557 // names dynamically to figure out how to dispatch to them. If it becomes more complicated than this we can 558 // turn the g_dispatch_functions char * array into a template table, and populate the DispatchFunction map 559 // from there. 560 561 for (int i = 0; g_dispatch_functions[i].name != NULL; i++) 562 { 563 ConstString name_const_str(g_dispatch_functions[i].name); 564 const Symbol *msgSend_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (name_const_str, eSymbolTypeCode); 565 if (msgSend_symbol) 566 { 567 // FixMe: Make g_dispatch_functions static table of DispatchFunctions, and have the map be address->index. 568 // Problem is we also need to lookup the dispatch function. For now we could have a side table of stret & non-stret 569 // dispatch functions. If that's as complex as it gets, we're fine. 570 571 lldb::addr_t sym_addr = msgSend_symbol->GetValue().GetOpcodeLoadAddress(target); 572 573 m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i)); 574 } 575 } 576 577 // Build our vtable dispatch handler here: 578 m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); 579 if (m_vtables_ap.get()) 580 m_vtables_ap->ReadRegions(); 581 } 582 583 ThreadPlanSP 584 AppleObjCTrampolineHandler::GetStepThroughDispatchPlan (Thread &thread, bool stop_others) 585 { 586 ThreadPlanSP ret_plan_sp; 587 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); 588 589 DispatchFunction this_dispatch; 590 bool found_it = false; 591 592 // First step is to look and see if we are in one of the known ObjC dispatch functions. We've already compiled 593 // a table of same, so consult it. 594 595 MsgsendMap::iterator pos; 596 pos = m_msgSend_map.find (curr_pc); 597 if (pos != m_msgSend_map.end()) 598 { 599 this_dispatch = g_dispatch_functions[(*pos).second]; 600 found_it = true; 601 } 602 603 // Next check to see if we are in a vtable region: 604 605 if (!found_it) 606 { 607 uint32_t flags; 608 if (m_vtables_ap.get()) 609 { 610 found_it = m_vtables_ap->IsAddressInVTables (curr_pc, flags); 611 if (found_it) 612 { 613 this_dispatch.name = "vtable"; 614 this_dispatch.stret_return 615 = (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; 616 this_dispatch.is_super = false; 617 this_dispatch.is_super2 = false; 618 this_dispatch.fixedup = DispatchFunction::eFixUpFixed; 619 } 620 } 621 } 622 623 if (found_it) 624 { 625 LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); 626 627 // We are decoding a method dispatch. 628 // First job is to pull the arguments out: 629 630 lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); 631 632 Process *process = thread.CalculateProcess(); 633 const ABI *abi = process->GetABI().get(); 634 if (abi == NULL) 635 return ret_plan_sp; 636 637 Target *target = thread.CalculateTarget(); 638 639 ClangASTContext *clang_ast_context = target->GetScratchClangASTContext(); 640 ValueList argument_values; 641 Value void_ptr_value; 642 lldb::clang_type_t clang_void_ptr_type = clang_ast_context->GetVoidPtrType(false); 643 void_ptr_value.SetValueType (Value::eValueTypeScalar); 644 void_ptr_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type); 645 646 int obj_index; 647 int sel_index; 648 649 // If this is a struct return dispatch, then the first argument is the 650 // return struct pointer, and the object is the second, and the selector is the third. 651 // Otherwise the object is the first and the selector the second. 652 if (this_dispatch.stret_return) 653 { 654 obj_index = 1; 655 sel_index = 2; 656 argument_values.PushValue(void_ptr_value); 657 argument_values.PushValue(void_ptr_value); 658 argument_values.PushValue(void_ptr_value); 659 } 660 else 661 { 662 obj_index = 0; 663 sel_index = 1; 664 argument_values.PushValue(void_ptr_value); 665 argument_values.PushValue(void_ptr_value); 666 } 667 668 669 bool success = abi->GetArgumentValues (thread, argument_values); 670 if (!success) 671 return ret_plan_sp; 672 673 ExecutionContext exe_ctx; 674 thread.CalculateExecutionContext (exe_ctx); 675 676 // isa_addr will store the class pointer that the method is being dispatched to - so either the class 677 // directly or the super class if this is one of the objc_msgSendSuper flavors. That's mostly used to 678 // look up the class/selector pair in our cache. 679 680 lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; 681 lldb::addr_t sel_addr = argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); 682 683 // Figure out the class this is being dispatched to and see if we've already cached this method call, 684 // If so we can push a run-to-address plan directly. Otherwise we have to figure out where 685 // the implementation lives. 686 687 if (this_dispatch.is_super) 688 { 689 if (this_dispatch.is_super2) 690 { 691 // In the objc_msgSendSuper2 case, we don't get the object directly, we get a structure containing 692 // the object and the class to which the super message is being sent. So we need to dig the super 693 // out of the class and use that. 694 695 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 696 super_value.GetScalar() += process->GetAddressByteSize(); 697 super_value.ResolveValue (&exe_ctx, clang_ast_context->getASTContext()); 698 699 if (super_value.GetScalar().IsValid()) 700 { 701 702 // isa_value now holds the class pointer. The second word of the class pointer is the super-class pointer: 703 super_value.GetScalar() += process->GetAddressByteSize(); 704 super_value.ResolveValue (&exe_ctx, clang_ast_context->getASTContext()); 705 if (super_value.GetScalar().IsValid()) 706 isa_addr = super_value.GetScalar().ULongLong(); 707 else 708 { 709 if (log) 710 log->Printf("Failed to extract the super class value from the class in objc_super."); 711 } 712 } 713 else 714 { 715 if (log) 716 log->Printf("Failed to extract the class value from objc_super."); 717 } 718 } 719 else 720 { 721 // In the objc_msgSendSuper case, we don't get the object directly, we get a two element structure containing 722 // the object and the super class to which the super message is being sent. So the class we want is 723 // the second element of this structure. 724 725 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 726 super_value.GetScalar() += process->GetAddressByteSize(); 727 super_value.ResolveValue (&exe_ctx, clang_ast_context->getASTContext()); 728 729 if (super_value.GetScalar().IsValid()) 730 { 731 isa_addr = super_value.GetScalar().ULongLong(); 732 } 733 else 734 { 735 if (log) 736 log->Printf("Failed to extract the class value from objc_super."); 737 } 738 } 739 } 740 else 741 { 742 // In the direct dispatch case, the object->isa is the class pointer we want. 743 744 // This is a little cheesy, but since object->isa is the first field, 745 // making the object value a load address value and resolving it will get 746 // the pointer sized data pointed to by that value... 747 748 // Note, it isn't a fatal error not to be able to get the address from the object, since this might 749 // be a "tagged pointer" which isn't a real object, but rather some word length encoded dingus. 750 751 Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); 752 753 isa_value.SetValueType(Value::eValueTypeLoadAddress); 754 isa_value.ResolveValue(&exe_ctx, clang_ast_context->getASTContext()); 755 if (isa_value.GetScalar().IsValid()) 756 { 757 isa_addr = isa_value.GetScalar().ULongLong(); 758 } 759 else 760 { 761 if (log) 762 log->Printf("Failed to extract the isa value from object."); 763 } 764 765 } 766 767 // Okay, we've got the address of the class for which we're resolving this, let's see if it's in our cache: 768 lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; 769 770 if (isa_addr != LLDB_INVALID_ADDRESS) 771 { 772 if (log) 773 { 774 log->Printf("Resolving call for class - 0x%llx and selector - 0x%llx", 775 isa_addr, sel_addr); 776 } 777 ObjCLanguageRuntime *objc_runtime = m_process_sp->GetObjCLanguageRuntime (); 778 assert(objc_runtime != NULL); 779 780 impl_addr = objc_runtime->LookupInMethodCache (isa_addr, sel_addr); 781 } 782 783 if (impl_addr != LLDB_INVALID_ADDRESS) 784 { 785 // Yup, it was in the cache, so we can run to that address directly. 786 787 if (log) 788 log->Printf ("Found implementation address in cache: 0x%llx", impl_addr); 789 790 ret_plan_sp.reset (new ThreadPlanRunToAddress (thread, impl_addr, stop_others)); 791 } 792 else 793 { 794 // We haven't seen this class/selector pair yet. Look it up. 795 StreamString errors; 796 Address impl_code_address; 797 798 ValueList dispatch_values; 799 800 // We've will inject a little function in the target that takes the object, selector and some flags, 801 // and figures out the implementation. Looks like: 802 // void *__lldb_objc_find_implementation_for_selector (void *object, 803 // void *sel, 804 // int is_stret, 805 // int is_super, 806 // int is_super2, 807 // int is_fixup, 808 // int is_fixed, 809 // int debug) 810 // So set up the arguments for that call. 811 812 dispatch_values.PushValue (*(argument_values.GetValueAtIndex(obj_index))); 813 dispatch_values.PushValue (*(argument_values.GetValueAtIndex(sel_index))); 814 815 Value flag_value; 816 lldb::clang_type_t clang_int_type 817 = clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(lldb::eEncodingSint, 32); 818 flag_value.SetValueType (Value::eValueTypeScalar); 819 flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); 820 821 if (this_dispatch.stret_return) 822 flag_value.GetScalar() = 1; 823 else 824 flag_value.GetScalar() = 0; 825 dispatch_values.PushValue (flag_value); 826 827 if (this_dispatch.is_super) 828 flag_value.GetScalar() = 1; 829 else 830 flag_value.GetScalar() = 0; 831 dispatch_values.PushValue (flag_value); 832 833 if (this_dispatch.is_super2) 834 flag_value.GetScalar() = 1; 835 else 836 flag_value.GetScalar() = 0; 837 dispatch_values.PushValue (flag_value); 838 839 switch (this_dispatch.fixedup) 840 { 841 case DispatchFunction::eFixUpNone: 842 flag_value.GetScalar() = 0; 843 dispatch_values.PushValue (flag_value); 844 dispatch_values.PushValue (flag_value); 845 break; 846 case DispatchFunction::eFixUpFixed: 847 flag_value.GetScalar() = 1; 848 dispatch_values.PushValue (flag_value); 849 flag_value.GetScalar() = 1; 850 dispatch_values.PushValue (flag_value); 851 break; 852 case DispatchFunction::eFixUpToFix: 853 flag_value.GetScalar() = 1; 854 dispatch_values.PushValue (flag_value); 855 flag_value.GetScalar() = 0; 856 dispatch_values.PushValue (flag_value); 857 break; 858 } 859 if (log) 860 flag_value.GetScalar() = 1; 861 else 862 flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. 863 dispatch_values.PushValue (flag_value); 864 865 // Now, if we haven't already, make and insert the function as a ClangUtilityFunction, and make and insert 866 // it's runner ClangFunction. 867 { 868 // Scope for mutex locker: 869 Mutex::Locker locker(m_impl_function_mutex); 870 871 // First stage is to make the ClangUtility to hold our injected function: 872 873 #define USE_BUILTIN_FUNCTION 0 // Define this to 1 and we will use the get_implementation function found in the target. 874 // This is useful for debugging additions to the get_impl function 'cause you don't have 875 // to bother with string-ifying the code into g_lookup_implementation_function_code. 876 877 if (USE_BUILTIN_FUNCTION) 878 { 879 ConstString our_utility_function_name("__lldb_objc_find_implementation_for_selector"); 880 SymbolContextList sc_list; 881 882 exe_ctx.GetTargetRef().GetImages().FindSymbolsWithNameAndType (our_utility_function_name, eSymbolTypeCode, sc_list); 883 if (sc_list.GetSize() == 1) 884 { 885 SymbolContext sc; 886 sc_list.GetContextAtIndex(0, sc); 887 if (sc.symbol != NULL) 888 impl_code_address = sc.symbol->GetValue(); 889 890 //lldb::addr_t addr = impl_code_address.GetOpcodeLoadAddress (exe_ctx.GetTargetPtr()); 891 //printf ("Getting address for our_utility_function: 0x%llx.\n", addr); 892 } 893 else 894 { 895 //printf ("Could not find implementation function address.\n"); 896 return ret_plan_sp; 897 } 898 } 899 else if (!m_impl_code.get()) 900 { 901 m_impl_code.reset (new ClangUtilityFunction (g_lookup_implementation_function_code, 902 g_lookup_implementation_function_name)); 903 if (!m_impl_code->Install(errors, exe_ctx)) 904 { 905 if (log) 906 log->Printf ("Failed to install implementation lookup: %s.", errors.GetData()); 907 m_impl_code.reset(); 908 return ret_plan_sp; 909 } 910 impl_code_address.Clear(); 911 impl_code_address.SetOffset(m_impl_code->StartAddress()); 912 } 913 else 914 { 915 impl_code_address.Clear(); 916 impl_code_address.SetOffset(m_impl_code->StartAddress()); 917 } 918 919 // Next make the runner function for our implementation utility function. 920 if (!m_impl_function.get()) 921 { 922 m_impl_function.reset(new ClangFunction (thread, 923 clang_ast_context, 924 clang_void_ptr_type, 925 impl_code_address, 926 dispatch_values)); 927 928 errors.Clear(); 929 unsigned num_errors = m_impl_function->CompileFunction(errors); 930 if (num_errors) 931 { 932 if (log) 933 log->Printf ("Error compiling function: \"%s\".", errors.GetData()); 934 return ret_plan_sp; 935 } 936 937 errors.Clear(); 938 if (!m_impl_function->WriteFunctionWrapper(exe_ctx, errors)) 939 { 940 if (log) 941 log->Printf ("Error Inserting function: \"%s\".", errors.GetData()); 942 return ret_plan_sp; 943 } 944 } 945 946 } 947 948 errors.Clear(); 949 950 // Now write down the argument values for this particular call. This looks like it might be a race condition 951 // if other threads were calling into here, but actually it isn't because we allocate a new args structure for 952 // this call by passing args_addr = LLDB_INVALID_ADDRESS... 953 954 lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; 955 if (!m_impl_function->WriteFunctionArguments (exe_ctx, args_addr, impl_code_address, dispatch_values, errors)) 956 return ret_plan_sp; 957 958 ret_plan_sp.reset (new AppleThreadPlanStepThroughObjCTrampoline (thread, this, args_addr, 959 dispatch_values.GetValueAtIndex(0)->GetScalar().ULongLong(), 960 isa_addr, sel_addr, 961 stop_others)); 962 if (log) 963 { 964 StreamString s; 965 ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); 966 log->Printf("Using ObjC step plan: %s.\n", s.GetData()); 967 } 968 } 969 } 970 971 return ret_plan_sp; 972 } 973 974 ClangFunction * 975 AppleObjCTrampolineHandler::GetLookupImplementationWrapperFunction () 976 { 977 return m_impl_function.get(); 978 } 979