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 "lldb/lldb-python.h" 11 12 #include "AppleObjCTrampolineHandler.h" 13 14 // C Includes 15 // C++ Includes 16 // Other libraries and framework includes 17 // Project includes 18 #include "AppleThreadPlanStepThroughObjCTrampoline.h" 19 20 #include "lldb/Breakpoint/StoppointCallbackContext.h" 21 #include "lldb/Core/ConstString.h" 22 #include "lldb/Core/Debugger.h" 23 #include "lldb/Core/Log.h" 24 #include "lldb/Core/Module.h" 25 #include "lldb/Core/Value.h" 26 #include "lldb/Expression/ClangExpression.h" 27 #include "lldb/Expression/ClangFunction.h" 28 #include "lldb/Expression/ClangUtilityFunction.h" 29 #include "lldb/Host/FileSpec.h" 30 #include "lldb/Symbol/ClangASTContext.h" 31 #include "lldb/Symbol/Symbol.h" 32 #include "lldb/Target/ObjCLanguageRuntime.h" 33 #include "lldb/Target/Process.h" 34 #include "lldb/Target/RegisterContext.h" 35 #include "lldb/Target/Target.h" 36 #include "lldb/Target/Thread.h" 37 #include "lldb/Target/ExecutionContext.h" 38 #include "lldb/Target/ThreadPlanRunToAddress.h" 39 40 #include "llvm/ADT/STLExtras.h" 41 42 using namespace lldb; 43 using namespace lldb_private; 44 45 const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = "__lldb_objc_find_implementation_for_selector"; 46 const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_code = NULL; 47 const char *AppleObjCTrampolineHandler::g_lookup_implementation_with_stret_function_code = " \n\ 48 extern \"C\" \n\ 49 { \n\ 50 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 51 extern void *class_getMethodImplementation_stret(void *objc_class, void *sel); \n\ 52 extern void * sel_getUid(char *name); \n\ 53 extern int printf(const char *format, ...); \n\ 54 } \n\ 55 extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ 56 void *sel, \n\ 57 int is_stret, \n\ 58 int is_super, \n\ 59 int is_super2, \n\ 60 int is_fixup, \n\ 61 int is_fixed, \n\ 62 int debug) \n\ 63 { \n\ 64 struct __lldb_imp_return_struct \n\ 65 { \n\ 66 void *class_addr; \n\ 67 void *sel_addr; \n\ 68 void *impl_addr; \n\ 69 }; \n\ 70 \n\ 71 struct __lldb_objc_class { \n\ 72 void *isa; \n\ 73 void *super_ptr; \n\ 74 }; \n\ 75 struct __lldb_objc_super { \n\ 76 void *reciever; \n\ 77 struct __lldb_objc_class *class_ptr; \n\ 78 }; \n\ 79 struct __lldb_msg_ref { \n\ 80 void *dont_know; \n\ 81 void *sel; \n\ 82 }; \n\ 83 \n\ 84 struct __lldb_imp_return_struct return_struct; \n\ 85 \n\ 86 if (debug) \n\ 87 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ 88 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 89 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ 90 if (is_super) \n\ 91 { \n\ 92 if (is_super2) \n\ 93 { \n\ 94 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ 95 } \n\ 96 else \n\ 97 { \n\ 98 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ 99 } \n\ 100 } \n\ 101 else \n\ 102 { \n\ 103 void *class_ptr = (void *) [(id) object class]; \n\ 104 if (class_ptr == object) \n\ 105 { \n\ 106 struct __lldb_objc_class *class_as_class_struct = (struct __lldb_objc_class *) class_ptr; \n\ 107 if (debug) \n\ 108 printf (\"Found a class object, need to return the meta class 0x%p -> 0x%p\\n\", \n\ 109 class_ptr, class_as_class_struct->isa); \n\ 110 return_struct.class_addr = class_as_class_struct->isa; \n\ 111 } \n\ 112 else \n\ 113 { \n\ 114 if (debug) \n\ 115 printf (\"[object class] returned: 0x%p.\\n\", class_ptr); \n\ 116 return_struct.class_addr = class_ptr; \n\ 117 } \n\ 118 } \n\ 119 \n\ 120 if (is_fixup) \n\ 121 { \n\ 122 if (is_fixed) \n\ 123 { \n\ 124 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 125 } \n\ 126 else \n\ 127 { \n\ 128 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 129 return_struct.sel_addr = sel_getUid (sel_name); \n\ 130 if (debug) \n\ 131 printf (\"\\n*** Got fixed up selector: 0x%p for name %s.\\n\", \n\ 132 return_struct.sel_addr, sel_name); \n\ 133 } \n\ 134 } \n\ 135 else \n\ 136 { \n\ 137 return_struct.sel_addr = sel; \n\ 138 } \n\ 139 \n\ 140 if (is_stret) \n\ 141 { \n\ 142 return_struct.impl_addr = class_getMethodImplementation_stret (return_struct.class_addr, \n\ 143 return_struct.sel_addr); \n\ 144 } \n\ 145 else \n\ 146 { \n\ 147 return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ 148 return_struct.sel_addr); \n\ 149 } \n\ 150 if (debug) \n\ 151 printf (\"\\n*** Returning implementation: 0x%p.\\n\", return_struct.impl_addr); \n\ 152 \n\ 153 return return_struct.impl_addr; \n\ 154 } \n\ 155 "; 156 const char *AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code = " \n\ 157 extern \"C\" \n\ 158 { \n\ 159 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 160 extern void * sel_getUid(char *name); \n\ 161 extern int printf(const char *format, ...); \n\ 162 } \n\ 163 extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ 164 void *sel, \n\ 165 int is_stret, \n\ 166 int is_super, \n\ 167 int is_super2, \n\ 168 int is_fixup, \n\ 169 int is_fixed, \n\ 170 int debug) \n\ 171 { \n\ 172 struct __lldb_imp_return_struct \n\ 173 { \n\ 174 void *class_addr; \n\ 175 void *sel_addr; \n\ 176 void *impl_addr; \n\ 177 }; \n\ 178 \n\ 179 struct __lldb_objc_class { \n\ 180 void *isa; \n\ 181 void *super_ptr; \n\ 182 }; \n\ 183 struct __lldb_objc_super { \n\ 184 void *reciever; \n\ 185 struct __lldb_objc_class *class_ptr; \n\ 186 }; \n\ 187 struct __lldb_msg_ref { \n\ 188 void *dont_know; \n\ 189 void *sel; \n\ 190 }; \n\ 191 \n\ 192 struct __lldb_imp_return_struct return_struct; \n\ 193 \n\ 194 if (debug) \n\ 195 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ 196 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 197 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ 198 if (is_super) \n\ 199 { \n\ 200 if (is_super2) \n\ 201 { \n\ 202 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ 203 } \n\ 204 else \n\ 205 { \n\ 206 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ 207 } \n\ 208 } \n\ 209 else \n\ 210 { \n\ 211 void *class_ptr = (void *) [(id) object class]; \n\ 212 if (class_ptr == object) \n\ 213 { \n\ 214 struct __lldb_objc_class *class_as_class_struct = (struct __lldb_objc_class *) class_ptr; \n\ 215 if (debug) \n\ 216 printf (\"Found a class object, need to return the meta class 0x%p -> 0x%p\\n\", \n\ 217 class_ptr, class_as_class_struct->isa); \n\ 218 return_struct.class_addr = class_as_class_struct->isa; \n\ 219 } \n\ 220 else \n\ 221 { \n\ 222 if (debug) \n\ 223 printf (\"[object class] returned: 0x%p.\\n\", class_ptr); \n\ 224 return_struct.class_addr = class_ptr; \n\ 225 } \n\ 226 } \n\ 227 \n\ 228 if (is_fixup) \n\ 229 { \n\ 230 if (is_fixed) \n\ 231 { \n\ 232 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 233 } \n\ 234 else \n\ 235 { \n\ 236 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 237 return_struct.sel_addr = sel_getUid (sel_name); \n\ 238 if (debug) \n\ 239 printf (\"\\n*** Got fixed up selector: 0x%p for name %s.\\n\", \n\ 240 return_struct.sel_addr, sel_name); \n\ 241 } \n\ 242 } \n\ 243 else \n\ 244 { \n\ 245 return_struct.sel_addr = sel; \n\ 246 } \n\ 247 \n\ 248 return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ 249 return_struct.sel_addr); \n\ 250 if (debug) \n\ 251 printf (\"\\n*** Returning implementation: 0x%p.\\n\", return_struct.impl_addr); \n\ 252 \n\ 253 return return_struct.impl_addr; \n\ 254 } \n\ 255 "; 256 257 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion(AppleObjCVTables *owner, lldb::addr_t header_addr) : 258 m_valid (true), 259 m_owner(owner), 260 m_header_addr (header_addr), 261 m_code_start_addr(0), 262 m_code_end_addr (0), 263 m_next_region (0) 264 { 265 SetUpRegion (); 266 } 267 268 AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() 269 { 270 } 271 272 void 273 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() 274 { 275 // The header looks like: 276 // 277 // uint16_t headerSize 278 // uint16_t descSize 279 // uint32_t descCount 280 // void * next 281 // 282 // First read in the header: 283 284 char memory_buffer[16]; 285 Process *process = m_owner->GetProcess(); 286 DataExtractor data(memory_buffer, sizeof(memory_buffer), 287 process->GetByteOrder(), 288 process->GetAddressByteSize()); 289 size_t actual_size = 8 + process->GetAddressByteSize(); 290 Error error; 291 size_t bytes_read = process->ReadMemory (m_header_addr, memory_buffer, actual_size, error); 292 if (bytes_read != actual_size) 293 { 294 m_valid = false; 295 return; 296 } 297 298 lldb::offset_t offset = 0; 299 const uint16_t header_size = data.GetU16(&offset); 300 const uint16_t descriptor_size = data.GetU16(&offset); 301 const size_t num_descriptors = data.GetU32(&offset); 302 303 m_next_region = data.GetPointer(&offset); 304 305 // If the header size is 0, that means we've come in too early before this data is set up. 306 // Set ourselves as not valid, and continue. 307 if (header_size == 0 || num_descriptors == 0) 308 { 309 m_valid = false; 310 return; 311 } 312 313 // Now read in all the descriptors: 314 // The descriptor looks like: 315 // 316 // uint32_t offset 317 // uint32_t flags 318 // 319 // Where offset is either 0 - in which case it is unused, or 320 // it is the offset of the vtable code from the beginning of the descriptor record. 321 // Below, we'll convert that into an absolute code address, since I don't want to have 322 // to compute it over and over. 323 324 // Ingest the whole descriptor array: 325 const lldb::addr_t desc_ptr = m_header_addr + header_size; 326 const size_t desc_array_size = num_descriptors * descriptor_size; 327 DataBufferSP data_sp(new DataBufferHeap (desc_array_size, '\0')); 328 uint8_t* dst = (uint8_t*)data_sp->GetBytes(); 329 330 DataExtractor desc_extractor (dst, desc_array_size, 331 process->GetByteOrder(), 332 process->GetAddressByteSize()); 333 bytes_read = process->ReadMemory(desc_ptr, dst, desc_array_size, error); 334 if (bytes_read != desc_array_size) 335 { 336 m_valid = false; 337 return; 338 } 339 340 // The actual code for the vtables will be laid out consecutively, so I also 341 // compute the start and end of the whole code block. 342 343 offset = 0; 344 m_code_start_addr = 0; 345 m_code_end_addr = 0; 346 347 for (size_t i = 0; i < num_descriptors; i++) 348 { 349 lldb::addr_t start_offset = offset; 350 uint32_t voffset = desc_extractor.GetU32 (&offset); 351 uint32_t flags = desc_extractor.GetU32 (&offset); 352 lldb::addr_t code_addr = desc_ptr + start_offset + voffset; 353 m_descriptors.push_back (VTableDescriptor(flags, code_addr)); 354 355 if (m_code_start_addr == 0 || code_addr < m_code_start_addr) 356 m_code_start_addr = code_addr; 357 if (code_addr > m_code_end_addr) 358 m_code_end_addr = code_addr; 359 360 offset = start_offset + descriptor_size; 361 } 362 // Finally, a little bird told me that all the vtable code blocks are the same size. 363 // Let's compute the blocks and if they are all the same add the size to the code end address: 364 lldb::addr_t code_size = 0; 365 bool all_the_same = true; 366 for (size_t i = 0; i < num_descriptors - 1; i++) 367 { 368 lldb::addr_t this_size = m_descriptors[i + 1].code_start - m_descriptors[i].code_start; 369 if (code_size == 0) 370 code_size = this_size; 371 else 372 { 373 if (this_size != code_size) 374 all_the_same = false; 375 if (this_size > code_size) 376 code_size = this_size; 377 } 378 } 379 if (all_the_same) 380 m_code_end_addr += code_size; 381 } 382 383 bool 384 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::AddressInRegion (lldb::addr_t addr, uint32_t &flags) 385 { 386 if (!IsValid()) 387 return false; 388 389 if (addr < m_code_start_addr || addr > m_code_end_addr) 390 return false; 391 392 std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end(); 393 for (pos = m_descriptors.begin(); pos != end; pos++) 394 { 395 if (addr <= (*pos).code_start) 396 { 397 flags = (*pos).flags; 398 return true; 399 } 400 } 401 return false; 402 } 403 404 void 405 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump (Stream &s) 406 { 407 s.Printf ("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n", 408 m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); 409 size_t num_elements = m_descriptors.size(); 410 for (size_t i = 0; i < num_elements; i++) 411 { 412 s.Indent(); 413 s.Printf ("Code start: 0x%" PRIx64 " Flags: %d\n", m_descriptors[i].code_start, m_descriptors[i].flags); 414 } 415 } 416 417 AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables (const ProcessSP &process_sp, 418 const ModuleSP &objc_module_sp) : 419 m_process_sp (process_sp), 420 m_trampoline_header (LLDB_INVALID_ADDRESS), 421 m_trampolines_changed_bp_id (LLDB_INVALID_BREAK_ID), 422 m_objc_module_sp (objc_module_sp) 423 { 424 425 } 426 427 AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() 428 { 429 if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) 430 m_process_sp->GetTarget().RemoveBreakpointByID (m_trampolines_changed_bp_id); 431 } 432 433 bool 434 AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols () 435 { 436 if (m_trampoline_header != LLDB_INVALID_ADDRESS) 437 return true; 438 Target &target = m_process_sp->GetTarget(); 439 440 const ModuleList &target_modules = target.GetImages(); 441 Mutex::Locker modules_locker(target_modules.GetMutex()); 442 size_t num_modules = target_modules.GetSize(); 443 if (!m_objc_module_sp) 444 { 445 for (size_t i = 0; i < num_modules; i++) 446 { 447 if (m_process_sp->GetObjCLanguageRuntime()->IsModuleObjCLibrary (target_modules.GetModuleAtIndexUnlocked(i))) 448 { 449 m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i); 450 break; 451 } 452 } 453 } 454 455 if (m_objc_module_sp) 456 { 457 ConstString trampoline_name ("gdb_objc_trampolines"); 458 const Symbol *trampoline_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (trampoline_name, 459 eSymbolTypeData); 460 if (trampoline_symbol != NULL) 461 { 462 if (!trampoline_symbol->GetAddress().IsValid()) 463 return false; 464 465 m_trampoline_header = trampoline_symbol->GetAddress().GetLoadAddress(&target); 466 if (m_trampoline_header == LLDB_INVALID_ADDRESS) 467 return false; 468 469 // Next look up the "changed" symbol and set a breakpoint on that... 470 ConstString changed_name ("gdb_objc_trampolines_changed"); 471 const Symbol *changed_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (changed_name, 472 eSymbolTypeCode); 473 if (changed_symbol != NULL) 474 { 475 if (!changed_symbol->GetAddress().IsValid()) 476 return false; 477 478 lldb::addr_t changed_addr = changed_symbol->GetAddress().GetOpcodeLoadAddress (&target); 479 if (changed_addr != LLDB_INVALID_ADDRESS) 480 { 481 BreakpointSP trampolines_changed_bp_sp = target.CreateBreakpoint (changed_addr, true); 482 if (trampolines_changed_bp_sp) 483 { 484 m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); 485 trampolines_changed_bp_sp->SetCallback (RefreshTrampolines, this, true); 486 trampolines_changed_bp_sp->SetBreakpointKind ("objc-trampolines-changed"); 487 return true; 488 } 489 } 490 } 491 } 492 } 493 494 return false; 495 } 496 497 bool 498 AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines (void *baton, 499 StoppointCallbackContext *context, 500 lldb::user_id_t break_id, 501 lldb::user_id_t break_loc_id) 502 { 503 AppleObjCVTables *vtable_handler = (AppleObjCVTables *) baton; 504 if (vtable_handler->InitializeVTableSymbols()) 505 { 506 // The Update function is called with the address of an added region. So we grab that address, and 507 // feed it into ReadRegions. Of course, our friend the ABI will get the values for us. 508 ExecutionContext exe_ctx (context->exe_ctx_ref); 509 Process *process = exe_ctx.GetProcessPtr(); 510 const ABI *abi = process->GetABI().get(); 511 512 ClangASTContext *clang_ast_context = process->GetTarget().GetScratchClangASTContext(); 513 ValueList argument_values; 514 Value input_value; 515 ClangASTType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 516 517 input_value.SetValueType (Value::eValueTypeScalar); 518 //input_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type); 519 input_value.SetClangType (clang_void_ptr_type); 520 argument_values.PushValue(input_value); 521 522 bool success = abi->GetArgumentValues (exe_ctx.GetThreadRef(), argument_values); 523 if (!success) 524 return false; 525 526 // Now get a pointer value from the zeroth argument. 527 Error error; 528 DataExtractor data; 529 error = argument_values.GetValueAtIndex(0)->GetValueAsData (&exe_ctx, 530 data, 531 0, 532 NULL); 533 lldb::offset_t offset = 0; 534 lldb::addr_t region_addr = data.GetPointer(&offset); 535 536 if (region_addr != 0) 537 vtable_handler->ReadRegions(region_addr); 538 } 539 return false; 540 } 541 542 bool 543 AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions () 544 { 545 // The no argument version reads the start region from the value of the gdb_regions_header, and 546 // gets started from there. 547 548 m_regions.clear(); 549 if (!InitializeVTableSymbols()) 550 return false; 551 Error error; 552 lldb::addr_t region_addr = m_process_sp->ReadPointerFromMemory (m_trampoline_header, error); 553 if (error.Success()) 554 return ReadRegions (region_addr); 555 return false; 556 } 557 558 bool 559 AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions (lldb::addr_t region_addr) 560 { 561 if (!m_process_sp) 562 return false; 563 564 Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); 565 566 // We aren't starting at the trampoline symbol. 567 InitializeVTableSymbols (); 568 lldb::addr_t next_region = region_addr; 569 570 // Read in the sizes of the headers. 571 while (next_region != 0) 572 { 573 m_regions.push_back (VTableRegion(this, next_region)); 574 if (!m_regions.back().IsValid()) 575 { 576 m_regions.clear(); 577 return false; 578 } 579 if (log) 580 { 581 StreamString s; 582 m_regions.back().Dump(s); 583 log->Printf("Read vtable region: \n%s", s.GetData()); 584 } 585 586 next_region = m_regions.back().GetNextRegionAddr(); 587 } 588 589 return true; 590 } 591 592 bool 593 AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables (lldb::addr_t addr, uint32_t &flags) 594 { 595 region_collection::iterator pos, end = m_regions.end(); 596 for (pos = m_regions.begin(); pos != end; pos++) 597 { 598 if ((*pos).AddressInRegion (addr, flags)) 599 return true; 600 } 601 return false; 602 } 603 604 const AppleObjCTrampolineHandler::DispatchFunction 605 AppleObjCTrampolineHandler::g_dispatch_functions[] = 606 { 607 // NAME STRET SUPER SUPER2 FIXUP TYPE 608 {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone }, 609 {"objc_msgSend_fixup", false, false, false, DispatchFunction::eFixUpToFix }, 610 {"objc_msgSend_fixedup", false, false, false, DispatchFunction::eFixUpFixed }, 611 {"objc_msgSend_stret", true, false, false, DispatchFunction::eFixUpNone }, 612 {"objc_msgSend_stret_fixup", true, false, false, DispatchFunction::eFixUpToFix }, 613 {"objc_msgSend_stret_fixedup", true, false, false, DispatchFunction::eFixUpFixed }, 614 {"objc_msgSend_fpret", false, false, false, DispatchFunction::eFixUpNone }, 615 {"objc_msgSend_fpret_fixup", false, false, false, DispatchFunction::eFixUpToFix }, 616 {"objc_msgSend_fpret_fixedup", false, false, false, DispatchFunction::eFixUpFixed }, 617 {"objc_msgSend_fp2ret", false, false, true, DispatchFunction::eFixUpNone }, 618 {"objc_msgSend_fp2ret_fixup", false, false, true, DispatchFunction::eFixUpToFix }, 619 {"objc_msgSend_fp2ret_fixedup", false, false, true, DispatchFunction::eFixUpFixed }, 620 {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone }, 621 {"objc_msgSendSuper_stret", true, true, false, DispatchFunction::eFixUpNone }, 622 {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone }, 623 {"objc_msgSendSuper2_fixup", false, true, true, DispatchFunction::eFixUpToFix }, 624 {"objc_msgSendSuper2_fixedup", false, true, true, DispatchFunction::eFixUpFixed }, 625 {"objc_msgSendSuper2_stret", true, true, true, DispatchFunction::eFixUpNone }, 626 {"objc_msgSendSuper2_stret_fixup", true, true, true, DispatchFunction::eFixUpToFix }, 627 {"objc_msgSendSuper2_stret_fixedup", true, true, true, DispatchFunction::eFixUpFixed }, 628 }; 629 630 AppleObjCTrampolineHandler::AppleObjCTrampolineHandler (const ProcessSP &process_sp, 631 const ModuleSP &objc_module_sp) : 632 m_process_sp (process_sp), 633 m_objc_module_sp (objc_module_sp), 634 m_impl_fn_addr (LLDB_INVALID_ADDRESS), 635 m_impl_stret_fn_addr (LLDB_INVALID_ADDRESS), 636 m_msg_forward_addr (LLDB_INVALID_ADDRESS) 637 { 638 // Look up the known resolution functions: 639 640 ConstString get_impl_name("class_getMethodImplementation"); 641 ConstString get_impl_stret_name("class_getMethodImplementation_stret"); 642 ConstString msg_forward_name("_objc_msgForward"); 643 ConstString msg_forward_stret_name("_objc_msgForward_stret"); 644 645 Target *target = m_process_sp ? &m_process_sp->GetTarget() : NULL; 646 const Symbol *class_getMethodImplementation = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_name, eSymbolTypeCode); 647 const Symbol *class_getMethodImplementation_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_stret_name, eSymbolTypeCode); 648 const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType (msg_forward_name, eSymbolTypeCode); 649 const Symbol *msg_forward_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (msg_forward_stret_name, eSymbolTypeCode); 650 651 if (class_getMethodImplementation) 652 m_impl_fn_addr = class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress (target); 653 if (class_getMethodImplementation_stret) 654 m_impl_stret_fn_addr = class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress (target); 655 if (msg_forward) 656 m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target); 657 if (msg_forward_stret) 658 m_msg_forward_stret_addr = msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target); 659 660 // FIXME: Do some kind of logging here. 661 if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) 662 { 663 // If we can't even find the ordinary get method implementation function, then we aren't going to be able to 664 // step through any method dispatches. Warn to that effect and get out of here. 665 if (process_sp->CanJIT()) 666 { 667 process_sp->GetTarget().GetDebugger().GetErrorStream().Printf("Could not find implementation lookup function \"%s\"" 668 " step in through ObjC method dispatch will not work.\n", 669 get_impl_name.AsCString()); 670 } 671 return; 672 } 673 else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) 674 { 675 // It there is no stret return lookup function, assume that it is the same as the straight lookup: 676 m_impl_stret_fn_addr = m_impl_fn_addr; 677 // Also we will use the version of the lookup code that doesn't rely on the stret version of the function. 678 g_lookup_implementation_function_code = g_lookup_implementation_no_stret_function_code; 679 } 680 else 681 { 682 g_lookup_implementation_function_code = g_lookup_implementation_with_stret_function_code; 683 } 684 685 // Look up the addresses for the objc dispatch functions and cache them. For now I'm inspecting the symbol 686 // names dynamically to figure out how to dispatch to them. If it becomes more complicated than this we can 687 // turn the g_dispatch_functions char * array into a template table, and populate the DispatchFunction map 688 // from there. 689 690 for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) 691 { 692 ConstString name_const_str(g_dispatch_functions[i].name); 693 const Symbol *msgSend_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (name_const_str, eSymbolTypeCode); 694 if (msgSend_symbol) 695 { 696 // FixMe: Make g_dispatch_functions static table of DispatchFunctions, and have the map be address->index. 697 // Problem is we also need to lookup the dispatch function. For now we could have a side table of stret & non-stret 698 // dispatch functions. If that's as complex as it gets, we're fine. 699 700 lldb::addr_t sym_addr = msgSend_symbol->GetAddress().GetOpcodeLoadAddress(target); 701 702 m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i)); 703 } 704 } 705 706 // Build our vtable dispatch handler here: 707 m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); 708 if (m_vtables_ap.get()) 709 m_vtables_ap->ReadRegions(); 710 } 711 712 lldb::addr_t 713 AppleObjCTrampolineHandler::SetupDispatchFunction (Thread &thread, ValueList &dispatch_values) 714 { 715 ExecutionContext exe_ctx (thread.shared_from_this()); 716 Address impl_code_address; 717 StreamString errors; 718 Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); 719 lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; 720 721 // Scope for mutex locker: 722 { 723 Mutex::Locker locker(m_impl_function_mutex); 724 725 // First stage is to make the ClangUtility to hold our injected function: 726 727 #define USE_BUILTIN_FUNCTION 0 // Define this to 1 and we will use the get_implementation function found in the target. 728 // This is useful for debugging additions to the get_impl function 'cause you don't have 729 // to bother with string-ifying the code into g_lookup_implementation_function_code. 730 731 if (USE_BUILTIN_FUNCTION) 732 { 733 ConstString our_utility_function_name("__lldb_objc_find_implementation_for_selector"); 734 SymbolContextList sc_list; 735 736 exe_ctx.GetTargetRef().GetImages().FindSymbolsWithNameAndType (our_utility_function_name, eSymbolTypeCode, sc_list); 737 if (sc_list.GetSize() == 1) 738 { 739 SymbolContext sc; 740 sc_list.GetContextAtIndex(0, sc); 741 if (sc.symbol != NULL) 742 impl_code_address = sc.symbol->GetAddress(); 743 744 //lldb::addr_t addr = impl_code_address.GetOpcodeLoadAddress (exe_ctx.GetTargetPtr()); 745 //printf ("Getting address for our_utility_function: 0x%" PRIx64 ".\n", addr); 746 } 747 else 748 { 749 //printf ("Could not find implementation function address.\n"); 750 return args_addr; 751 } 752 } 753 else if (!m_impl_code.get()) 754 { 755 if (g_lookup_implementation_function_code != NULL) 756 { 757 m_impl_code.reset (new ClangUtilityFunction (g_lookup_implementation_function_code, 758 g_lookup_implementation_function_name)); 759 if (!m_impl_code->Install(errors, exe_ctx)) 760 { 761 if (log) 762 log->Printf ("Failed to install implementation lookup: %s.", errors.GetData()); 763 m_impl_code.reset(); 764 return args_addr; 765 } 766 } 767 else 768 { 769 if (log) 770 log->Printf("No method lookup implementation code."); 771 errors.Printf ("No method lookup implementation code found."); 772 return LLDB_INVALID_ADDRESS; 773 } 774 775 impl_code_address.Clear(); 776 impl_code_address.SetOffset(m_impl_code->StartAddress()); 777 } 778 else 779 { 780 impl_code_address.Clear(); 781 impl_code_address.SetOffset(m_impl_code->StartAddress()); 782 } 783 784 // Next make the runner function for our implementation utility function. 785 if (!m_impl_function.get()) 786 { 787 ClangASTContext *clang_ast_context = thread.GetProcess()->GetTarget().GetScratchClangASTContext(); 788 ClangASTType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 789 m_impl_function.reset(new ClangFunction (thread, 790 clang_void_ptr_type, 791 impl_code_address, 792 dispatch_values)); 793 794 errors.Clear(); 795 unsigned num_errors = m_impl_function->CompileFunction(errors); 796 if (num_errors) 797 { 798 if (log) 799 log->Printf ("Error compiling function: \"%s\".", errors.GetData()); 800 return args_addr; 801 } 802 803 errors.Clear(); 804 if (!m_impl_function->WriteFunctionWrapper(exe_ctx, errors)) 805 { 806 if (log) 807 log->Printf ("Error Inserting function: \"%s\".", errors.GetData()); 808 return args_addr; 809 } 810 } 811 } 812 813 errors.Clear(); 814 815 // Now write down the argument values for this particular call. This looks like it might be a race condition 816 // if other threads were calling into here, but actually it isn't because we allocate a new args structure for 817 // this call by passing args_addr = LLDB_INVALID_ADDRESS... 818 819 if (!m_impl_function->WriteFunctionArguments (exe_ctx, args_addr, impl_code_address, dispatch_values, errors)) 820 { 821 if (log) 822 log->Printf ("Error writing function arguments: \"%s\".", errors.GetData()); 823 return args_addr; 824 } 825 826 return args_addr; 827 } 828 829 ThreadPlanSP 830 AppleObjCTrampolineHandler::GetStepThroughDispatchPlan (Thread &thread, bool stop_others) 831 { 832 ThreadPlanSP ret_plan_sp; 833 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); 834 835 DispatchFunction this_dispatch; 836 bool found_it = false; 837 838 // First step is to look and see if we are in one of the known ObjC dispatch functions. We've already compiled 839 // a table of same, so consult it. 840 841 MsgsendMap::iterator pos; 842 pos = m_msgSend_map.find (curr_pc); 843 if (pos != m_msgSend_map.end()) 844 { 845 this_dispatch = g_dispatch_functions[(*pos).second]; 846 found_it = true; 847 } 848 849 // Next check to see if we are in a vtable region: 850 851 if (!found_it) 852 { 853 uint32_t flags; 854 if (m_vtables_ap.get()) 855 { 856 found_it = m_vtables_ap->IsAddressInVTables (curr_pc, flags); 857 if (found_it) 858 { 859 this_dispatch.name = "vtable"; 860 this_dispatch.stret_return 861 = (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; 862 this_dispatch.is_super = false; 863 this_dispatch.is_super2 = false; 864 this_dispatch.fixedup = DispatchFunction::eFixUpFixed; 865 } 866 } 867 } 868 869 if (found_it) 870 { 871 Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); 872 873 // We are decoding a method dispatch. 874 // First job is to pull the arguments out: 875 876 lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); 877 878 const ABI *abi = NULL; 879 ProcessSP process_sp (thread.CalculateProcess()); 880 if (process_sp) 881 abi = process_sp->GetABI().get(); 882 if (abi == NULL) 883 return ret_plan_sp; 884 885 TargetSP target_sp (thread.CalculateTarget()); 886 887 ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext(); 888 ValueList argument_values; 889 Value void_ptr_value; 890 ClangASTType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 891 void_ptr_value.SetValueType (Value::eValueTypeScalar); 892 //void_ptr_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type); 893 void_ptr_value.SetClangType (clang_void_ptr_type); 894 895 int obj_index; 896 int sel_index; 897 898 // If this is a struct return dispatch, then the first argument is the 899 // return struct pointer, and the object is the second, and the selector is the third. 900 // Otherwise the object is the first and the selector the second. 901 if (this_dispatch.stret_return) 902 { 903 obj_index = 1; 904 sel_index = 2; 905 argument_values.PushValue(void_ptr_value); 906 argument_values.PushValue(void_ptr_value); 907 argument_values.PushValue(void_ptr_value); 908 } 909 else 910 { 911 obj_index = 0; 912 sel_index = 1; 913 argument_values.PushValue(void_ptr_value); 914 argument_values.PushValue(void_ptr_value); 915 } 916 917 918 bool success = abi->GetArgumentValues (thread, argument_values); 919 if (!success) 920 return ret_plan_sp; 921 922 lldb::addr_t obj_addr = argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong(); 923 if (obj_addr == 0x0) 924 { 925 if (log) 926 log->Printf("Asked to step to dispatch to nil object, returning empty plan."); 927 return ret_plan_sp; 928 } 929 930 ExecutionContext exe_ctx (thread.shared_from_this()); 931 Process *process = exe_ctx.GetProcessPtr(); 932 // isa_addr will store the class pointer that the method is being dispatched to - so either the class 933 // directly or the super class if this is one of the objc_msgSendSuper flavors. That's mostly used to 934 // look up the class/selector pair in our cache. 935 936 lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; 937 lldb::addr_t sel_addr = argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); 938 939 // Figure out the class this is being dispatched to and see if we've already cached this method call, 940 // If so we can push a run-to-address plan directly. Otherwise we have to figure out where 941 // the implementation lives. 942 943 if (this_dispatch.is_super) 944 { 945 if (this_dispatch.is_super2) 946 { 947 // In the objc_msgSendSuper2 case, we don't get the object directly, we get a structure containing 948 // the object and the class to which the super message is being sent. So we need to dig the super 949 // out of the class and use that. 950 951 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 952 super_value.GetScalar() += process->GetAddressByteSize(); 953 super_value.ResolveValue (&exe_ctx); 954 955 if (super_value.GetScalar().IsValid()) 956 { 957 958 // isa_value now holds the class pointer. The second word of the class pointer is the super-class pointer: 959 super_value.GetScalar() += process->GetAddressByteSize(); 960 super_value.ResolveValue (&exe_ctx); 961 if (super_value.GetScalar().IsValid()) 962 isa_addr = super_value.GetScalar().ULongLong(); 963 else 964 { 965 if (log) 966 log->Printf("Failed to extract the super class value from the class in objc_super."); 967 } 968 } 969 else 970 { 971 if (log) 972 log->Printf("Failed to extract the class value from objc_super."); 973 } 974 } 975 else 976 { 977 // In the objc_msgSendSuper case, we don't get the object directly, we get a two element structure containing 978 // the object and the super class to which the super message is being sent. So the class we want is 979 // the second element of this structure. 980 981 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 982 super_value.GetScalar() += process->GetAddressByteSize(); 983 super_value.ResolveValue (&exe_ctx); 984 985 if (super_value.GetScalar().IsValid()) 986 { 987 isa_addr = super_value.GetScalar().ULongLong(); 988 } 989 else 990 { 991 if (log) 992 log->Printf("Failed to extract the class value from objc_super."); 993 } 994 } 995 } 996 else 997 { 998 // In the direct dispatch case, the object->isa is the class pointer we want. 999 1000 // This is a little cheesy, but since object->isa is the first field, 1001 // making the object value a load address value and resolving it will get 1002 // the pointer sized data pointed to by that value... 1003 1004 // Note, it isn't a fatal error not to be able to get the address from the object, since this might 1005 // be a "tagged pointer" which isn't a real object, but rather some word length encoded dingus. 1006 1007 Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); 1008 1009 isa_value.SetValueType(Value::eValueTypeLoadAddress); 1010 isa_value.ResolveValue(&exe_ctx); 1011 if (isa_value.GetScalar().IsValid()) 1012 { 1013 isa_addr = isa_value.GetScalar().ULongLong(); 1014 } 1015 else 1016 { 1017 if (log) 1018 log->Printf("Failed to extract the isa value from object."); 1019 } 1020 1021 } 1022 1023 // Okay, we've got the address of the class for which we're resolving this, let's see if it's in our cache: 1024 lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; 1025 1026 if (isa_addr != LLDB_INVALID_ADDRESS) 1027 { 1028 if (log) 1029 { 1030 log->Printf("Resolving call for class - 0x%" PRIx64 " and selector - 0x%" PRIx64, 1031 isa_addr, sel_addr); 1032 } 1033 ObjCLanguageRuntime *objc_runtime = m_process_sp->GetObjCLanguageRuntime (); 1034 assert(objc_runtime != NULL); 1035 1036 impl_addr = objc_runtime->LookupInMethodCache (isa_addr, sel_addr); 1037 } 1038 1039 if (impl_addr != LLDB_INVALID_ADDRESS) 1040 { 1041 // Yup, it was in the cache, so we can run to that address directly. 1042 1043 if (log) 1044 log->Printf ("Found implementation address in cache: 0x%" PRIx64, impl_addr); 1045 1046 ret_plan_sp.reset (new ThreadPlanRunToAddress (thread, impl_addr, stop_others)); 1047 } 1048 else 1049 { 1050 // We haven't seen this class/selector pair yet. Look it up. 1051 StreamString errors; 1052 Address impl_code_address; 1053 1054 ValueList dispatch_values; 1055 1056 // We've will inject a little function in the target that takes the object, selector and some flags, 1057 // and figures out the implementation. Looks like: 1058 // void *__lldb_objc_find_implementation_for_selector (void *object, 1059 // void *sel, 1060 // int is_stret, 1061 // int is_super, 1062 // int is_super2, 1063 // int is_fixup, 1064 // int is_fixed, 1065 // int debug) 1066 // So set up the arguments for that call. 1067 1068 dispatch_values.PushValue (*(argument_values.GetValueAtIndex(obj_index))); 1069 dispatch_values.PushValue (*(argument_values.GetValueAtIndex(sel_index))); 1070 1071 Value flag_value; 1072 ClangASTType clang_int_type = clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(lldb::eEncodingSint, 32); 1073 flag_value.SetValueType (Value::eValueTypeScalar); 1074 //flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); 1075 flag_value.SetClangType (clang_int_type); 1076 1077 if (this_dispatch.stret_return) 1078 flag_value.GetScalar() = 1; 1079 else 1080 flag_value.GetScalar() = 0; 1081 dispatch_values.PushValue (flag_value); 1082 1083 if (this_dispatch.is_super) 1084 flag_value.GetScalar() = 1; 1085 else 1086 flag_value.GetScalar() = 0; 1087 dispatch_values.PushValue (flag_value); 1088 1089 if (this_dispatch.is_super2) 1090 flag_value.GetScalar() = 1; 1091 else 1092 flag_value.GetScalar() = 0; 1093 dispatch_values.PushValue (flag_value); 1094 1095 switch (this_dispatch.fixedup) 1096 { 1097 case DispatchFunction::eFixUpNone: 1098 flag_value.GetScalar() = 0; 1099 dispatch_values.PushValue (flag_value); 1100 dispatch_values.PushValue (flag_value); 1101 break; 1102 case DispatchFunction::eFixUpFixed: 1103 flag_value.GetScalar() = 1; 1104 dispatch_values.PushValue (flag_value); 1105 flag_value.GetScalar() = 1; 1106 dispatch_values.PushValue (flag_value); 1107 break; 1108 case DispatchFunction::eFixUpToFix: 1109 flag_value.GetScalar() = 1; 1110 dispatch_values.PushValue (flag_value); 1111 flag_value.GetScalar() = 0; 1112 dispatch_values.PushValue (flag_value); 1113 break; 1114 } 1115 if (log && log->GetVerbose()) 1116 flag_value.GetScalar() = 1; 1117 else 1118 flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. 1119 dispatch_values.PushValue (flag_value); 1120 1121 1122 // The step through code might have to fill in the cache, so it is not safe to run only one thread. 1123 // So we override the stop_others value passed in to us here: 1124 const bool trampoline_stop_others = false; 1125 ret_plan_sp.reset (new AppleThreadPlanStepThroughObjCTrampoline (thread, 1126 this, 1127 dispatch_values, 1128 isa_addr, 1129 sel_addr, 1130 trampoline_stop_others)); 1131 if (log) 1132 { 1133 StreamString s; 1134 ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); 1135 log->Printf("Using ObjC step plan: %s.\n", s.GetData()); 1136 } 1137 } 1138 } 1139 1140 return ret_plan_sp; 1141 } 1142 1143 ClangFunction * 1144 AppleObjCTrampolineHandler::GetLookupImplementationWrapperFunction () 1145 { 1146 return m_impl_function.get(); 1147 } 1148
