AppleObjCTrampolineHandler.cpp revision 344779
1//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++ 2//-*-===// 3// 4// The LLVM Compiler Infrastructure 5// 6// This file is distributed under the University of Illinois Open Source 7// License. See LICENSE.TXT for details. 8// 9//===----------------------------------------------------------------------===// 10 11#include "AppleObjCTrampolineHandler.h" 12 13#include "AppleThreadPlanStepThroughObjCTrampoline.h" 14 15#include "lldb/Breakpoint/StoppointCallbackContext.h" 16#include "lldb/Core/Debugger.h" 17#include "lldb/Core/Module.h" 18#include "lldb/Core/StreamFile.h" 19#include "lldb/Core/Value.h" 20#include "lldb/Expression/DiagnosticManager.h" 21#include "lldb/Expression/FunctionCaller.h" 22#include "lldb/Expression/UserExpression.h" 23#include "lldb/Expression/UtilityFunction.h" 24#include "lldb/Symbol/ClangASTContext.h" 25#include "lldb/Symbol/Symbol.h" 26#include "lldb/Target/ABI.h" 27#include "lldb/Target/ExecutionContext.h" 28#include "lldb/Target/ObjCLanguageRuntime.h" 29#include "lldb/Target/Process.h" 30#include "lldb/Target/RegisterContext.h" 31#include "lldb/Target/Target.h" 32#include "lldb/Target/Thread.h" 33#include "lldb/Target/ThreadPlanRunToAddress.h" 34#include "lldb/Utility/ConstString.h" 35#include "lldb/Utility/FileSpec.h" 36#include "lldb/Utility/Log.h" 37 38#include "llvm/ADT/STLExtras.h" 39 40using namespace lldb; 41using namespace lldb_private; 42 43const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = 44 "__lldb_objc_find_implementation_for_selector"; 45const char *AppleObjCTrampolineHandler:: 46 g_lookup_implementation_with_stret_function_code = 47 " \n\ 48extern \"C\" \n\ 49{ \n\ 50 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 51 extern void *class_getMethodImplementation_stret(void *objc_class, \n\ 52 void *sel); \n\ 53 extern void * object_getClass (id object); \n\ 54 extern void * sel_getUid(char *name); \n\ 55 extern int printf(const char *format, ...); \n\ 56} \n\ 57extern \"C\" void * __lldb_objc_find_implementation_for_selector ( \n\ 58 void *object, \n\ 59 void *sel, \n\ 60 int is_stret, \n\ 61 int is_super, \n\ 62 int is_super2, \n\ 63 int is_fixup, \n\ 64 int is_fixed, \n\ 65 int debug) \n\ 66{ \n\ 67 struct __lldb_imp_return_struct \n\ 68 { \n\ 69 void *class_addr; \n\ 70 void *sel_addr; \n\ 71 void *impl_addr; \n\ 72 }; \n\ 73 \n\ 74 struct __lldb_objc_class { \n\ 75 void *isa; \n\ 76 void *super_ptr; \n\ 77 }; \n\ 78 struct __lldb_objc_super { \n\ 79 void *receiver; \n\ 80 struct __lldb_objc_class *class_ptr; \n\ 81 }; \n\ 82 struct __lldb_msg_ref { \n\ 83 void *dont_know; \n\ 84 void *sel; \n\ 85 }; \n\ 86 \n\ 87 struct __lldb_imp_return_struct return_struct; \n\ 88 \n\ 89 if (debug) \n\ 90 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \"\n\ 91 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 92 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed);\n\ 93 if (is_super) \n\ 94 { \n\ 95 if (is_super2) \n\ 96 { \n\ 97 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr;\n\ 98 } \n\ 99 else \n\ 100 { \n\ 101 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;\n\ 102 } \n\ 103 } \n\ 104 else \n\ 105 { \n\ 106 // This code seems a little funny, but has its reasons... \n\ 107 \n\ 108 // The call to [object class] is here because if this is a \n\ 109 // class, and has not been called into yet, we need to do \n\ 110 // something to force the class to initialize itself. \n\ 111 // Then the call to object_getClass will actually return the \n\ 112 // correct class, either the class if object is a class \n\ 113 // instance, or the meta-class if it is a class pointer. \n\ 114 void *class_ptr = (void *) [(id) object class]; \n\ 115 return_struct.class_addr = (id) object_getClass((id) object); \n\ 116 if (debug) \n\ 117 { \n\ 118 if (class_ptr == object) \n\ 119 { \n\ 120 printf (\"Found a class object, need to use the meta class %p -> %p\\n\",\n\ 121 class_ptr, return_struct.class_addr); \n\ 122 } \n\ 123 else \n\ 124 { \n\ 125 printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ 126 class_ptr, return_struct.class_addr); \n\ 127 } \n\ 128 } \n\ 129 } \n\ 130 \n\ 131 if (is_fixup) \n\ 132 { \n\ 133 if (is_fixed) \n\ 134 { \n\ 135 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 136 } \n\ 137 else \n\ 138 { \n\ 139 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 140 return_struct.sel_addr = sel_getUid (sel_name); \n\ 141 if (debug) \n\ 142 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\ 143 return_struct.sel_addr, sel_name); \n\ 144 } \n\ 145 } \n\ 146 else \n\ 147 { \n\ 148 return_struct.sel_addr = sel; \n\ 149 } \n\ 150 \n\ 151 if (is_stret) \n\ 152 { \n\ 153 return_struct.impl_addr = \n\ 154 class_getMethodImplementation_stret (return_struct.class_addr, \n\ 155 return_struct.sel_addr); \n\ 156 } \n\ 157 else \n\ 158 { \n\ 159 return_struct.impl_addr = \n\ 160 class_getMethodImplementation (return_struct.class_addr, \n\ 161 return_struct.sel_addr); \n\ 162 } \n\ 163 if (debug) \n\ 164 printf (\"\\n*** Returning implementation: %p.\\n\", \n\ 165 return_struct.impl_addr); \n\ 166 \n\ 167 return return_struct.impl_addr; \n\ 168} \n\ 169"; 170const char * 171 AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code = 172 " \n\ 173extern \"C\" \n\ 174{ \n\ 175 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 176 extern void * object_getClass (id object); \n\ 177 extern void * sel_getUid(char *name); \n\ 178 extern int printf(const char *format, ...); \n\ 179} \n\ 180extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ 181 void *sel, \n\ 182 int is_stret, \n\ 183 int is_super, \n\ 184 int is_super2, \n\ 185 int is_fixup, \n\ 186 int is_fixed, \n\ 187 int debug) \n\ 188{ \n\ 189 struct __lldb_imp_return_struct \n\ 190 { \n\ 191 void *class_addr; \n\ 192 void *sel_addr; \n\ 193 void *impl_addr; \n\ 194 }; \n\ 195 \n\ 196 struct __lldb_objc_class { \n\ 197 void *isa; \n\ 198 void *super_ptr; \n\ 199 }; \n\ 200 struct __lldb_objc_super { \n\ 201 void *receiver; \n\ 202 struct __lldb_objc_class *class_ptr; \n\ 203 }; \n\ 204 struct __lldb_msg_ref { \n\ 205 void *dont_know; \n\ 206 void *sel; \n\ 207 }; \n\ 208 \n\ 209 struct __lldb_imp_return_struct return_struct; \n\ 210 \n\ 211 if (debug) \n\ 212 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ 213 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 214 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ 215 if (is_super) \n\ 216 { \n\ 217 if (is_super2) \n\ 218 { \n\ 219 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ 220 } \n\ 221 else \n\ 222 { \n\ 223 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ 224 } \n\ 225 } \n\ 226 else \n\ 227 { \n\ 228 // This code seems a little funny, but has its reasons... \n\ 229 // The call to [object class] is here because if this is a class, and has not been called into \n\ 230 // yet, we need to do something to force the class to initialize itself. \n\ 231 // Then the call to object_getClass will actually return the correct class, either the class \n\ 232 // if object is a class instance, or the meta-class if it is a class pointer. \n\ 233 void *class_ptr = (void *) [(id) object class]; \n\ 234 return_struct.class_addr = (id) object_getClass((id) object); \n\ 235 if (debug) \n\ 236 { \n\ 237 if (class_ptr == object) \n\ 238 { \n\ 239 printf (\"Found a class object, need to return the meta class %p -> %p\\n\", \n\ 240 class_ptr, return_struct.class_addr); \n\ 241 } \n\ 242 else \n\ 243 { \n\ 244 printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ 245 class_ptr, return_struct.class_addr); \n\ 246 } \n\ 247 } \n\ 248 } \n\ 249 \n\ 250 if (is_fixup) \n\ 251 { \n\ 252 if (is_fixed) \n\ 253 { \n\ 254 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 255 } \n\ 256 else \n\ 257 { \n\ 258 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 259 return_struct.sel_addr = sel_getUid (sel_name); \n\ 260 if (debug) \n\ 261 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\ 262 return_struct.sel_addr, sel_name); \n\ 263 } \n\ 264 } \n\ 265 else \n\ 266 { \n\ 267 return_struct.sel_addr = sel; \n\ 268 } \n\ 269 \n\ 270 return_struct.impl_addr = \n\ 271 class_getMethodImplementation (return_struct.class_addr, \n\ 272 return_struct.sel_addr); \n\ 273 if (debug) \n\ 274 printf (\"\\n*** Returning implementation: 0x%p.\\n\", \n\ 275 return_struct.impl_addr); \n\ 276 \n\ 277 return return_struct.impl_addr; \n\ 278} \n\ 279"; 280 281AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion( 282 AppleObjCVTables *owner, lldb::addr_t header_addr) 283 : m_valid(true), m_owner(owner), m_header_addr(header_addr), 284 m_code_start_addr(0), m_code_end_addr(0), m_next_region(0) { 285 SetUpRegion(); 286} 287 288AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() {} 289 290void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() { 291 // The header looks like: 292 // 293 // uint16_t headerSize 294 // uint16_t descSize 295 // uint32_t descCount 296 // void * next 297 // 298 // First read in the header: 299 300 char memory_buffer[16]; 301 ProcessSP process_sp = m_owner->GetProcessSP(); 302 if (!process_sp) 303 return; 304 DataExtractor data(memory_buffer, sizeof(memory_buffer), 305 process_sp->GetByteOrder(), 306 process_sp->GetAddressByteSize()); 307 size_t actual_size = 8 + process_sp->GetAddressByteSize(); 308 Status error; 309 size_t bytes_read = 310 process_sp->ReadMemory(m_header_addr, memory_buffer, actual_size, error); 311 if (bytes_read != actual_size) { 312 m_valid = false; 313 return; 314 } 315 316 lldb::offset_t offset = 0; 317 const uint16_t header_size = data.GetU16(&offset); 318 const uint16_t descriptor_size = data.GetU16(&offset); 319 const size_t num_descriptors = data.GetU32(&offset); 320 321 m_next_region = data.GetPointer(&offset); 322 323 // If the header size is 0, that means we've come in too early before this 324 // data is set up. 325 // Set ourselves as not valid, and continue. 326 if (header_size == 0 || num_descriptors == 0) { 327 m_valid = false; 328 return; 329 } 330 331 // Now read in all the descriptors: 332 // The descriptor looks like: 333 // 334 // uint32_t offset 335 // uint32_t flags 336 // 337 // Where offset is either 0 - in which case it is unused, or it is 338 // the offset of the vtable code from the beginning of the 339 // descriptor record. Below, we'll convert that into an absolute 340 // code address, since I don't want to have to compute it over and 341 // over. 342 343 // Ingest the whole descriptor array: 344 const lldb::addr_t desc_ptr = m_header_addr + header_size; 345 const size_t desc_array_size = num_descriptors * descriptor_size; 346 DataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0')); 347 uint8_t *dst = (uint8_t *)data_sp->GetBytes(); 348 349 DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(), 350 process_sp->GetAddressByteSize()); 351 bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error); 352 if (bytes_read != desc_array_size) { 353 m_valid = false; 354 return; 355 } 356 357 // The actual code for the vtables will be laid out consecutively, so I also 358 // compute the start and end of the whole code block. 359 360 offset = 0; 361 m_code_start_addr = 0; 362 m_code_end_addr = 0; 363 364 for (size_t i = 0; i < num_descriptors; i++) { 365 lldb::addr_t start_offset = offset; 366 uint32_t voffset = desc_extractor.GetU32(&offset); 367 uint32_t flags = desc_extractor.GetU32(&offset); 368 lldb::addr_t code_addr = desc_ptr + start_offset + voffset; 369 m_descriptors.push_back(VTableDescriptor(flags, code_addr)); 370 371 if (m_code_start_addr == 0 || code_addr < m_code_start_addr) 372 m_code_start_addr = code_addr; 373 if (code_addr > m_code_end_addr) 374 m_code_end_addr = code_addr; 375 376 offset = start_offset + descriptor_size; 377 } 378 // Finally, a little bird told me that all the vtable code blocks 379 // are the same size. Let's compute the blocks and if they are all 380 // the same add the size to the code end address: 381 lldb::addr_t code_size = 0; 382 bool all_the_same = true; 383 for (size_t i = 0; i < num_descriptors - 1; i++) { 384 lldb::addr_t this_size = 385 m_descriptors[i + 1].code_start - m_descriptors[i].code_start; 386 if (code_size == 0) 387 code_size = this_size; 388 else { 389 if (this_size != code_size) 390 all_the_same = false; 391 if (this_size > code_size) 392 code_size = this_size; 393 } 394 } 395 if (all_the_same) 396 m_code_end_addr += code_size; 397} 398 399bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion:: 400 AddressInRegion(lldb::addr_t addr, uint32_t &flags) { 401 if (!IsValid()) 402 return false; 403 404 if (addr < m_code_start_addr || addr > m_code_end_addr) 405 return false; 406 407 std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end(); 408 for (pos = m_descriptors.begin(); pos != end; pos++) { 409 if (addr <= (*pos).code_start) { 410 flags = (*pos).flags; 411 return true; 412 } 413 } 414 return false; 415} 416 417void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump( 418 Stream &s) { 419 s.Printf("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64 420 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n", 421 m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); 422 size_t num_elements = m_descriptors.size(); 423 for (size_t i = 0; i < num_elements; i++) { 424 s.Indent(); 425 s.Printf("Code start: 0x%" PRIx64 " Flags: %d\n", 426 m_descriptors[i].code_start, m_descriptors[i].flags); 427 } 428} 429 430AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables( 431 const ProcessSP &process_sp, const ModuleSP &objc_module_sp) 432 : m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS), 433 m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID), 434 m_objc_module_sp(objc_module_sp) { 435 if (process_sp) 436 m_process_wp = process_sp; 437} 438 439AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() { 440 ProcessSP process_sp = GetProcessSP(); 441 if (process_sp) { 442 if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) 443 process_sp->GetTarget().RemoveBreakpointByID(m_trampolines_changed_bp_id); 444 } 445} 446 447bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() { 448 if (m_trampoline_header != LLDB_INVALID_ADDRESS) 449 return true; 450 451 ProcessSP process_sp = GetProcessSP(); 452 if (process_sp) { 453 Target &target = process_sp->GetTarget(); 454 455 const ModuleList &target_modules = target.GetImages(); 456 std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex()); 457 size_t num_modules = target_modules.GetSize(); 458 if (!m_objc_module_sp) { 459 for (size_t i = 0; i < num_modules; i++) { 460 if (process_sp->GetObjCLanguageRuntime()->IsModuleObjCLibrary( 461 target_modules.GetModuleAtIndexUnlocked(i))) { 462 m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i); 463 break; 464 } 465 } 466 } 467 468 if (m_objc_module_sp) { 469 ConstString trampoline_name("gdb_objc_trampolines"); 470 const Symbol *trampoline_symbol = 471 m_objc_module_sp->FindFirstSymbolWithNameAndType(trampoline_name, 472 eSymbolTypeData); 473 if (trampoline_symbol != NULL) { 474 m_trampoline_header = trampoline_symbol->GetLoadAddress(&target); 475 if (m_trampoline_header == LLDB_INVALID_ADDRESS) 476 return false; 477 478 // Next look up the "changed" symbol and set a breakpoint on that... 479 ConstString changed_name("gdb_objc_trampolines_changed"); 480 const Symbol *changed_symbol = 481 m_objc_module_sp->FindFirstSymbolWithNameAndType(changed_name, 482 eSymbolTypeCode); 483 if (changed_symbol != NULL) { 484 const Address changed_symbol_addr = changed_symbol->GetAddress(); 485 if (!changed_symbol_addr.IsValid()) 486 return false; 487 488 lldb::addr_t changed_addr = 489 changed_symbol_addr.GetOpcodeLoadAddress(&target); 490 if (changed_addr != LLDB_INVALID_ADDRESS) { 491 BreakpointSP trampolines_changed_bp_sp = 492 target.CreateBreakpoint(changed_addr, true, false); 493 if (trampolines_changed_bp_sp) { 494 m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); 495 trampolines_changed_bp_sp->SetCallback(RefreshTrampolines, this, 496 true); 497 trampolines_changed_bp_sp->SetBreakpointKind( 498 "objc-trampolines-changed"); 499 return true; 500 } 501 } 502 } 503 } 504 } 505 } 506 return false; 507} 508 509bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines( 510 void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id, 511 lldb::user_id_t break_loc_id) { 512 AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton; 513 if (vtable_handler->InitializeVTableSymbols()) { 514 // The Update function is called with the address of an added region. So we 515 // grab that address, and 516 // feed it into ReadRegions. Of course, our friend the ABI will get the 517 // values for us. 518 ExecutionContext exe_ctx(context->exe_ctx_ref); 519 Process *process = exe_ctx.GetProcessPtr(); 520 const ABI *abi = process->GetABI().get(); 521 522 ClangASTContext *clang_ast_context = 523 process->GetTarget().GetScratchClangASTContext(); 524 ValueList argument_values; 525 Value input_value; 526 CompilerType clang_void_ptr_type = 527 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 528 529 input_value.SetValueType(Value::eValueTypeScalar); 530 // input_value.SetContext (Value::eContextTypeClangType, 531 // clang_void_ptr_type); 532 input_value.SetCompilerType(clang_void_ptr_type); 533 argument_values.PushValue(input_value); 534 535 bool success = 536 abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values); 537 if (!success) 538 return false; 539 540 // Now get a pointer value from the zeroth argument. 541 Status error; 542 DataExtractor data; 543 error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data, 544 0, NULL); 545 lldb::offset_t offset = 0; 546 lldb::addr_t region_addr = data.GetPointer(&offset); 547 548 if (region_addr != 0) 549 vtable_handler->ReadRegions(region_addr); 550 } 551 return false; 552} 553 554bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() { 555 // The no argument version reads the start region from the value of 556 // the gdb_regions_header, and gets started from there. 557 558 m_regions.clear(); 559 if (!InitializeVTableSymbols()) 560 return false; 561 Status error; 562 ProcessSP process_sp = GetProcessSP(); 563 if (process_sp) { 564 lldb::addr_t region_addr = 565 process_sp->ReadPointerFromMemory(m_trampoline_header, error); 566 if (error.Success()) 567 return ReadRegions(region_addr); 568 } 569 return false; 570} 571 572bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions( 573 lldb::addr_t region_addr) { 574 ProcessSP process_sp = GetProcessSP(); 575 if (!process_sp) 576 return false; 577 578 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 579 580 // We aren't starting at the trampoline symbol. 581 InitializeVTableSymbols(); 582 lldb::addr_t next_region = region_addr; 583 584 // Read in the sizes of the headers. 585 while (next_region != 0) { 586 m_regions.push_back(VTableRegion(this, next_region)); 587 if (!m_regions.back().IsValid()) { 588 m_regions.clear(); 589 return false; 590 } 591 if (log) { 592 StreamString s; 593 m_regions.back().Dump(s); 594 log->Printf("Read vtable region: \n%s", s.GetData()); 595 } 596 597 next_region = m_regions.back().GetNextRegionAddr(); 598 } 599 600 return true; 601} 602 603bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables( 604 lldb::addr_t addr, uint32_t &flags) { 605 region_collection::iterator pos, end = m_regions.end(); 606 for (pos = m_regions.begin(); pos != end; pos++) { 607 if ((*pos).AddressInRegion(addr, flags)) 608 return true; 609 } 610 return false; 611} 612 613const AppleObjCTrampolineHandler::DispatchFunction 614 AppleObjCTrampolineHandler::g_dispatch_functions[] = { 615 // NAME STRET SUPER SUPER2 FIXUP TYPE 616 {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone}, 617 {"objc_msgSend_fixup", false, false, false, 618 DispatchFunction::eFixUpToFix}, 619 {"objc_msgSend_fixedup", false, false, false, 620 DispatchFunction::eFixUpFixed}, 621 {"objc_msgSend_stret", true, false, false, 622 DispatchFunction::eFixUpNone}, 623 {"objc_msgSend_stret_fixup", true, false, false, 624 DispatchFunction::eFixUpToFix}, 625 {"objc_msgSend_stret_fixedup", true, false, false, 626 DispatchFunction::eFixUpFixed}, 627 {"objc_msgSend_fpret", false, false, false, 628 DispatchFunction::eFixUpNone}, 629 {"objc_msgSend_fpret_fixup", false, false, false, 630 DispatchFunction::eFixUpToFix}, 631 {"objc_msgSend_fpret_fixedup", false, false, false, 632 DispatchFunction::eFixUpFixed}, 633 {"objc_msgSend_fp2ret", false, false, true, 634 DispatchFunction::eFixUpNone}, 635 {"objc_msgSend_fp2ret_fixup", false, false, true, 636 DispatchFunction::eFixUpToFix}, 637 {"objc_msgSend_fp2ret_fixedup", false, false, true, 638 DispatchFunction::eFixUpFixed}, 639 {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone}, 640 {"objc_msgSendSuper_stret", true, true, false, 641 DispatchFunction::eFixUpNone}, 642 {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone}, 643 {"objc_msgSendSuper2_fixup", false, true, true, 644 DispatchFunction::eFixUpToFix}, 645 {"objc_msgSendSuper2_fixedup", false, true, true, 646 DispatchFunction::eFixUpFixed}, 647 {"objc_msgSendSuper2_stret", true, true, true, 648 DispatchFunction::eFixUpNone}, 649 {"objc_msgSendSuper2_stret_fixup", true, true, true, 650 DispatchFunction::eFixUpToFix}, 651 {"objc_msgSendSuper2_stret_fixedup", true, true, true, 652 DispatchFunction::eFixUpFixed}, 653}; 654 655AppleObjCTrampolineHandler::AppleObjCTrampolineHandler( 656 const ProcessSP &process_sp, const ModuleSP &objc_module_sp) 657 : m_process_wp(), m_objc_module_sp(objc_module_sp), 658 m_lookup_implementation_function_code(nullptr), 659 m_impl_fn_addr(LLDB_INVALID_ADDRESS), 660 m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS), 661 m_msg_forward_addr(LLDB_INVALID_ADDRESS) { 662 if (process_sp) 663 m_process_wp = process_sp; 664 // Look up the known resolution functions: 665 666 ConstString get_impl_name("class_getMethodImplementation"); 667 ConstString get_impl_stret_name("class_getMethodImplementation_stret"); 668 ConstString msg_forward_name("_objc_msgForward"); 669 ConstString msg_forward_stret_name("_objc_msgForward_stret"); 670 671 Target *target = process_sp ? &process_sp->GetTarget() : NULL; 672 const Symbol *class_getMethodImplementation = 673 m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_name, 674 eSymbolTypeCode); 675 const Symbol *class_getMethodImplementation_stret = 676 m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_stret_name, 677 eSymbolTypeCode); 678 const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType( 679 msg_forward_name, eSymbolTypeCode); 680 const Symbol *msg_forward_stret = 681 m_objc_module_sp->FindFirstSymbolWithNameAndType(msg_forward_stret_name, 682 eSymbolTypeCode); 683 684 if (class_getMethodImplementation) 685 m_impl_fn_addr = 686 class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress( 687 target); 688 if (class_getMethodImplementation_stret) 689 m_impl_stret_fn_addr = 690 class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress( 691 target); 692 if (msg_forward) 693 m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target); 694 if (msg_forward_stret) 695 m_msg_forward_stret_addr = 696 msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target); 697 698 // FIXME: Do some kind of logging here. 699 if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) { 700 // If we can't even find the ordinary get method implementation function, 701 // then we aren't going to be able to 702 // step through any method dispatches. Warn to that effect and get out of 703 // here. 704 if (process_sp->CanJIT()) { 705 process_sp->GetTarget().GetDebugger().GetErrorFile()->Printf( 706 "Could not find implementation lookup function \"%s\"" 707 " step in through ObjC method dispatch will not work.\n", 708 get_impl_name.AsCString()); 709 } 710 return; 711 } else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) { 712 // It there is no stret return lookup function, assume that it is the same 713 // as the straight lookup: 714 m_impl_stret_fn_addr = m_impl_fn_addr; 715 // Also we will use the version of the lookup code that doesn't rely on the 716 // stret version of the function. 717 m_lookup_implementation_function_code = 718 g_lookup_implementation_no_stret_function_code; 719 } else { 720 m_lookup_implementation_function_code = 721 g_lookup_implementation_with_stret_function_code; 722 } 723 724 // Look up the addresses for the objc dispatch functions and cache 725 // them. For now I'm inspecting the symbol names dynamically to 726 // figure out how to dispatch to them. If it becomes more 727 // complicated than this we can turn the g_dispatch_functions char * 728 // array into a template table, and populate the DispatchFunction 729 // map from there. 730 731 for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) { 732 ConstString name_const_str(g_dispatch_functions[i].name); 733 const Symbol *msgSend_symbol = 734 m_objc_module_sp->FindFirstSymbolWithNameAndType(name_const_str, 735 eSymbolTypeCode); 736 if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) { 737 // FIXME: Make g_dispatch_functions static table of 738 // DispatchFunctions, and have the map be address->index. 739 // Problem is we also need to lookup the dispatch function. For 740 // now we could have a side table of stret & non-stret dispatch 741 // functions. If that's as complex as it gets, we're fine. 742 743 lldb::addr_t sym_addr = 744 msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target); 745 746 m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i)); 747 } 748 } 749 750 // Build our vtable dispatch handler here: 751 m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); 752 if (m_vtables_ap.get()) 753 m_vtables_ap->ReadRegions(); 754} 755 756lldb::addr_t 757AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread, 758 ValueList &dispatch_values) { 759 ThreadSP thread_sp(thread.shared_from_this()); 760 ExecutionContext exe_ctx(thread_sp); 761 DiagnosticManager diagnostics; 762 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 763 764 lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; 765 FunctionCaller *impl_function_caller = nullptr; 766 767 // Scope for mutex locker: 768 { 769 std::lock_guard<std::mutex> guard(m_impl_function_mutex); 770 771 // First stage is to make the ClangUtility to hold our injected function: 772 773 if (!m_impl_code.get()) { 774 if (m_lookup_implementation_function_code != NULL) { 775 Status error; 776 m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage( 777 m_lookup_implementation_function_code, eLanguageTypeObjC, 778 g_lookup_implementation_function_name, error)); 779 if (error.Fail()) { 780 if (log) 781 log->Printf( 782 "Failed to get Utility Function for implementation lookup: %s.", 783 error.AsCString()); 784 m_impl_code.reset(); 785 return args_addr; 786 } 787 788 if (!m_impl_code->Install(diagnostics, exe_ctx)) { 789 if (log) { 790 log->Printf("Failed to install implementation lookup."); 791 diagnostics.Dump(log); 792 } 793 m_impl_code.reset(); 794 return args_addr; 795 } 796 } else { 797 if (log) 798 log->Printf("No method lookup implementation code."); 799 return LLDB_INVALID_ADDRESS; 800 } 801 802 // Next make the runner function for our implementation utility function. 803 ClangASTContext *clang_ast_context = 804 thread.GetProcess()->GetTarget().GetScratchClangASTContext(); 805 CompilerType clang_void_ptr_type = 806 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 807 Status error; 808 809 impl_function_caller = m_impl_code->MakeFunctionCaller( 810 clang_void_ptr_type, dispatch_values, thread_sp, error); 811 if (error.Fail()) { 812 if (log) 813 log->Printf( 814 "Error getting function caller for dispatch lookup: \"%s\".", 815 error.AsCString()); 816 return args_addr; 817 } 818 } else { 819 impl_function_caller = m_impl_code->GetFunctionCaller(); 820 } 821 } 822 823 diagnostics.Clear(); 824 825 // Now write down the argument values for this particular call. 826 // This looks like it might be a race condition if other threads 827 // were calling into here, but actually it isn't because we allocate 828 // a new args structure for this call by passing args_addr = 829 // LLDB_INVALID_ADDRESS... 830 831 if (!impl_function_caller->WriteFunctionArguments( 832 exe_ctx, args_addr, dispatch_values, diagnostics)) { 833 if (log) { 834 log->Printf("Error writing function arguments."); 835 diagnostics.Dump(log); 836 } 837 return args_addr; 838 } 839 840 return args_addr; 841} 842 843ThreadPlanSP 844AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread, 845 bool stop_others) { 846 ThreadPlanSP ret_plan_sp; 847 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); 848 849 DispatchFunction this_dispatch; 850 bool found_it = false; 851 852 // First step is to look and see if we are in one of the known ObjC 853 // dispatch functions. We've already compiled a table of same, so 854 // consult it. 855 856 MsgsendMap::iterator pos; 857 pos = m_msgSend_map.find(curr_pc); 858 if (pos != m_msgSend_map.end()) { 859 this_dispatch = g_dispatch_functions[(*pos).second]; 860 found_it = true; 861 } 862 863 // Next check to see if we are in a vtable region: 864 865 if (!found_it) { 866 uint32_t flags; 867 if (m_vtables_ap.get()) { 868 found_it = m_vtables_ap->IsAddressInVTables(curr_pc, flags); 869 if (found_it) { 870 this_dispatch.name = "vtable"; 871 this_dispatch.stret_return = 872 (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == 873 AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; 874 this_dispatch.is_super = false; 875 this_dispatch.is_super2 = false; 876 this_dispatch.fixedup = DispatchFunction::eFixUpFixed; 877 } 878 } 879 } 880 881 if (found_it) { 882 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 883 884 // We are decoding a method dispatch. First job is to pull the 885 // arguments out: 886 887 lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); 888 889 const ABI *abi = NULL; 890 ProcessSP process_sp(thread.CalculateProcess()); 891 if (process_sp) 892 abi = process_sp->GetABI().get(); 893 if (abi == NULL) 894 return ret_plan_sp; 895 896 TargetSP target_sp(thread.CalculateTarget()); 897 898 ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext(); 899 ValueList argument_values; 900 Value void_ptr_value; 901 CompilerType clang_void_ptr_type = 902 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 903 void_ptr_value.SetValueType(Value::eValueTypeScalar); 904 // void_ptr_value.SetContext (Value::eContextTypeClangType, 905 // clang_void_ptr_type); 906 void_ptr_value.SetCompilerType(clang_void_ptr_type); 907 908 int obj_index; 909 int sel_index; 910 911 // If this is a struct return dispatch, then the first argument is 912 // the return struct pointer, and the object is the second, and 913 // the selector is the third. Otherwise the object is the first 914 // and the selector the second. 915 if (this_dispatch.stret_return) { 916 obj_index = 1; 917 sel_index = 2; 918 argument_values.PushValue(void_ptr_value); 919 argument_values.PushValue(void_ptr_value); 920 argument_values.PushValue(void_ptr_value); 921 } else { 922 obj_index = 0; 923 sel_index = 1; 924 argument_values.PushValue(void_ptr_value); 925 argument_values.PushValue(void_ptr_value); 926 } 927 928 bool success = abi->GetArgumentValues(thread, argument_values); 929 if (!success) 930 return ret_plan_sp; 931 932 lldb::addr_t obj_addr = 933 argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong(); 934 if (obj_addr == 0x0) { 935 if (log) 936 log->Printf( 937 "Asked to step to dispatch to nil object, returning empty plan."); 938 return ret_plan_sp; 939 } 940 941 ExecutionContext exe_ctx(thread.shared_from_this()); 942 Process *process = exe_ctx.GetProcessPtr(); 943 // isa_addr will store the class pointer that the method is being 944 // dispatched to - so either the class directly or the super class 945 // if this is one of the objc_msgSendSuper flavors. That's mostly 946 // used to look up the class/selector pair in our cache. 947 948 lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; 949 lldb::addr_t sel_addr = 950 argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); 951 952 // Figure out the class this is being dispatched to and see if 953 // we've already cached this method call, If so we can push a 954 // run-to-address plan directly. Otherwise we have to figure out 955 // where the implementation lives. 956 957 if (this_dispatch.is_super) { 958 if (this_dispatch.is_super2) { 959 // In the objc_msgSendSuper2 case, we don't get the object 960 // directly, we get a structure containing the object and the 961 // class to which the super message is being sent. So we need 962 // to dig the super out of the class and use that. 963 964 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 965 super_value.GetScalar() += process->GetAddressByteSize(); 966 super_value.ResolveValue(&exe_ctx); 967 968 if (super_value.GetScalar().IsValid()) { 969 970 // isa_value now holds the class pointer. The second word of the 971 // class pointer is the super-class pointer: 972 super_value.GetScalar() += process->GetAddressByteSize(); 973 super_value.ResolveValue(&exe_ctx); 974 if (super_value.GetScalar().IsValid()) 975 isa_addr = super_value.GetScalar().ULongLong(); 976 else { 977 if (log) 978 log->Printf("Failed to extract the super class value from the " 979 "class in objc_super."); 980 } 981 } else { 982 if (log) 983 log->Printf("Failed to extract the class value from objc_super."); 984 } 985 } else { 986 // In the objc_msgSendSuper case, we don't get the object 987 // directly, we get a two element structure containing the 988 // object and the super class to which the super message is 989 // being sent. So the class we want is the second element of 990 // this structure. 991 992 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 993 super_value.GetScalar() += process->GetAddressByteSize(); 994 super_value.ResolveValue(&exe_ctx); 995 996 if (super_value.GetScalar().IsValid()) { 997 isa_addr = super_value.GetScalar().ULongLong(); 998 } else { 999 if (log) 1000 log->Printf("Failed to extract the class value from objc_super."); 1001 } 1002 } 1003 } else { 1004 // In the direct dispatch case, the object->isa is the class pointer we 1005 // want. 1006 1007 // This is a little cheesy, but since object->isa is the first field, 1008 // making the object value a load address value and resolving it will get 1009 // the pointer sized data pointed to by that value... 1010 1011 // Note, it isn't a fatal error not to be able to get the 1012 // address from the object, since this might be a "tagged 1013 // pointer" which isn't a real object, but rather some word 1014 // length encoded dingus. 1015 1016 Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); 1017 1018 isa_value.SetValueType(Value::eValueTypeLoadAddress); 1019 isa_value.ResolveValue(&exe_ctx); 1020 if (isa_value.GetScalar().IsValid()) { 1021 isa_addr = isa_value.GetScalar().ULongLong(); 1022 } else { 1023 if (log) 1024 log->Printf("Failed to extract the isa value from object."); 1025 } 1026 } 1027 1028 // Okay, we've got the address of the class for which we're resolving this, 1029 // let's see if it's in our cache: 1030 lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; 1031 1032 if (isa_addr != LLDB_INVALID_ADDRESS) { 1033 if (log) { 1034 log->Printf("Resolving call for class - 0x%" PRIx64 1035 " and selector - 0x%" PRIx64, 1036 isa_addr, sel_addr); 1037 } 1038 ObjCLanguageRuntime *objc_runtime = 1039 thread.GetProcess()->GetObjCLanguageRuntime(); 1040 assert(objc_runtime != NULL); 1041 1042 impl_addr = objc_runtime->LookupInMethodCache(isa_addr, sel_addr); 1043 } 1044 1045 if (impl_addr != LLDB_INVALID_ADDRESS) { 1046 // Yup, it was in the cache, so we can run to that address directly. 1047 1048 if (log) 1049 log->Printf("Found implementation address in cache: 0x%" PRIx64, 1050 impl_addr); 1051 1052 ret_plan_sp.reset( 1053 new ThreadPlanRunToAddress(thread, impl_addr, stop_others)); 1054 } else { 1055 // We haven't seen this class/selector pair yet. Look it up. 1056 StreamString errors; 1057 Address impl_code_address; 1058 1059 ValueList dispatch_values; 1060 1061 // We've will inject a little function in the target that takes the 1062 // object, selector and some flags, 1063 // and figures out the implementation. Looks like: 1064 // void *__lldb_objc_find_implementation_for_selector (void *object, 1065 // void *sel, 1066 // int is_stret, 1067 // int is_super, 1068 // int is_super2, 1069 // int is_fixup, 1070 // int is_fixed, 1071 // int debug) 1072 // So set up the arguments for that call. 1073 1074 dispatch_values.PushValue(*(argument_values.GetValueAtIndex(obj_index))); 1075 dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index))); 1076 1077 Value flag_value; 1078 CompilerType clang_int_type = 1079 clang_ast_context->GetBuiltinTypeForEncodingAndBitSize( 1080 lldb::eEncodingSint, 32); 1081 flag_value.SetValueType(Value::eValueTypeScalar); 1082 // flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); 1083 flag_value.SetCompilerType(clang_int_type); 1084 1085 if (this_dispatch.stret_return) 1086 flag_value.GetScalar() = 1; 1087 else 1088 flag_value.GetScalar() = 0; 1089 dispatch_values.PushValue(flag_value); 1090 1091 if (this_dispatch.is_super) 1092 flag_value.GetScalar() = 1; 1093 else 1094 flag_value.GetScalar() = 0; 1095 dispatch_values.PushValue(flag_value); 1096 1097 if (this_dispatch.is_super2) 1098 flag_value.GetScalar() = 1; 1099 else 1100 flag_value.GetScalar() = 0; 1101 dispatch_values.PushValue(flag_value); 1102 1103 switch (this_dispatch.fixedup) { 1104 case DispatchFunction::eFixUpNone: 1105 flag_value.GetScalar() = 0; 1106 dispatch_values.PushValue(flag_value); 1107 dispatch_values.PushValue(flag_value); 1108 break; 1109 case DispatchFunction::eFixUpFixed: 1110 flag_value.GetScalar() = 1; 1111 dispatch_values.PushValue(flag_value); 1112 flag_value.GetScalar() = 1; 1113 dispatch_values.PushValue(flag_value); 1114 break; 1115 case DispatchFunction::eFixUpToFix: 1116 flag_value.GetScalar() = 1; 1117 dispatch_values.PushValue(flag_value); 1118 flag_value.GetScalar() = 0; 1119 dispatch_values.PushValue(flag_value); 1120 break; 1121 } 1122 if (log && log->GetVerbose()) 1123 flag_value.GetScalar() = 1; 1124 else 1125 flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. 1126 dispatch_values.PushValue(flag_value); 1127 1128 // The step through code might have to fill in the cache, so it 1129 // is not safe to run only one thread. So we override the 1130 // stop_others value passed in to us here: 1131 const bool trampoline_stop_others = false; 1132 ret_plan_sp.reset(new AppleThreadPlanStepThroughObjCTrampoline( 1133 thread, this, dispatch_values, isa_addr, sel_addr, 1134 trampoline_stop_others)); 1135 if (log) { 1136 StreamString s; 1137 ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); 1138 log->Printf("Using ObjC step plan: %s.\n", s.GetData()); 1139 } 1140 } 1141 } 1142 1143 return ret_plan_sp; 1144} 1145 1146FunctionCaller * 1147AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() { 1148 return m_impl_code->GetFunctionCaller(); 1149} 1150