AppleObjCTrampolineHandler.cpp revision 341825
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// C Includes 14// C++ Includes 15// Other libraries and framework includes 16// Project includes 17#include "AppleThreadPlanStepThroughObjCTrampoline.h" 18 19#include "lldb/Breakpoint/StoppointCallbackContext.h" 20#include "lldb/Core/Debugger.h" 21#include "lldb/Core/Module.h" 22#include "lldb/Core/StreamFile.h" 23#include "lldb/Core/Value.h" 24#include "lldb/Expression/DiagnosticManager.h" 25#include "lldb/Expression/FunctionCaller.h" 26#include "lldb/Expression/UserExpression.h" 27#include "lldb/Expression/UtilityFunction.h" 28#include "lldb/Symbol/ClangASTContext.h" 29#include "lldb/Symbol/Symbol.h" 30#include "lldb/Target/ABI.h" 31#include "lldb/Target/ExecutionContext.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/ThreadPlanRunToAddress.h" 38#include "lldb/Utility/ConstString.h" 39#include "lldb/Utility/FileSpec.h" 40#include "lldb/Utility/Log.h" 41 42#include "llvm/ADT/STLExtras.h" 43 44using namespace lldb; 45using namespace lldb_private; 46 47const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = 48 "__lldb_objc_find_implementation_for_selector"; 49const char *AppleObjCTrampolineHandler:: 50 g_lookup_implementation_with_stret_function_code = 51 " \n\ 52extern \"C\" \n\ 53{ \n\ 54 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 55 extern void *class_getMethodImplementation_stret(void *objc_class, \n\ 56 void *sel); \n\ 57 extern void * object_getClass (id object); \n\ 58 extern void * sel_getUid(char *name); \n\ 59 extern int printf(const char *format, ...); \n\ 60} \n\ 61extern \"C\" void * __lldb_objc_find_implementation_for_selector ( \n\ 62 void *object, \n\ 63 void *sel, \n\ 64 int is_stret, \n\ 65 int is_super, \n\ 66 int is_super2, \n\ 67 int is_fixup, \n\ 68 int is_fixed, \n\ 69 int debug) \n\ 70{ \n\ 71 struct __lldb_imp_return_struct \n\ 72 { \n\ 73 void *class_addr; \n\ 74 void *sel_addr; \n\ 75 void *impl_addr; \n\ 76 }; \n\ 77 \n\ 78 struct __lldb_objc_class { \n\ 79 void *isa; \n\ 80 void *super_ptr; \n\ 81 }; \n\ 82 struct __lldb_objc_super { \n\ 83 void *reciever; \n\ 84 struct __lldb_objc_class *class_ptr; \n\ 85 }; \n\ 86 struct __lldb_msg_ref { \n\ 87 void *dont_know; \n\ 88 void *sel; \n\ 89 }; \n\ 90 \n\ 91 struct __lldb_imp_return_struct return_struct; \n\ 92 \n\ 93 if (debug) \n\ 94 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \"\n\ 95 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 96 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed);\n\ 97 if (is_super) \n\ 98 { \n\ 99 if (is_super2) \n\ 100 { \n\ 101 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr;\n\ 102 } \n\ 103 else \n\ 104 { \n\ 105 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;\n\ 106 } \n\ 107 } \n\ 108 else \n\ 109 { \n\ 110 // This code seems a little funny, but has its reasons... \n\ 111 \n\ 112 // The call to [object class] is here because if this is a \n\ 113 // class, and has not been called into yet, we need to do \n\ 114 // something to force the class to initialize itself. \n\ 115 // Then the call to object_getClass will actually return the \n\ 116 // correct class, either the class if object is a class \n\ 117 // instance, or the meta-class if it is a class pointer. \n\ 118 void *class_ptr = (void *) [(id) object class]; \n\ 119 return_struct.class_addr = (id) object_getClass((id) object); \n\ 120 if (debug) \n\ 121 { \n\ 122 if (class_ptr == object) \n\ 123 { \n\ 124 printf (\"Found a class object, need to use the meta class %p -> %p\\n\",\n\ 125 class_ptr, return_struct.class_addr); \n\ 126 } \n\ 127 else \n\ 128 { \n\ 129 printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ 130 class_ptr, return_struct.class_addr); \n\ 131 } \n\ 132 } \n\ 133 } \n\ 134 \n\ 135 if (is_fixup) \n\ 136 { \n\ 137 if (is_fixed) \n\ 138 { \n\ 139 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 140 } \n\ 141 else \n\ 142 { \n\ 143 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 144 return_struct.sel_addr = sel_getUid (sel_name); \n\ 145 if (debug) \n\ 146 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\ 147 return_struct.sel_addr, sel_name); \n\ 148 } \n\ 149 } \n\ 150 else \n\ 151 { \n\ 152 return_struct.sel_addr = sel; \n\ 153 } \n\ 154 \n\ 155 if (is_stret) \n\ 156 { \n\ 157 return_struct.impl_addr = \n\ 158 class_getMethodImplementation_stret (return_struct.class_addr, \n\ 159 return_struct.sel_addr); \n\ 160 } \n\ 161 else \n\ 162 { \n\ 163 return_struct.impl_addr = \n\ 164 class_getMethodImplementation (return_struct.class_addr, \n\ 165 return_struct.sel_addr); \n\ 166 } \n\ 167 if (debug) \n\ 168 printf (\"\\n*** Returning implementation: %p.\\n\", \n\ 169 return_struct.impl_addr); \n\ 170 \n\ 171 return return_struct.impl_addr; \n\ 172} \n\ 173"; 174const char * 175 AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code = 176 " \n\ 177extern \"C\" \n\ 178{ \n\ 179 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 180 extern void * object_getClass (id object); \n\ 181 extern void * sel_getUid(char *name); \n\ 182 extern int printf(const char *format, ...); \n\ 183} \n\ 184extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ 185 void *sel, \n\ 186 int is_stret, \n\ 187 int is_super, \n\ 188 int is_super2, \n\ 189 int is_fixup, \n\ 190 int is_fixed, \n\ 191 int debug) \n\ 192{ \n\ 193 struct __lldb_imp_return_struct \n\ 194 { \n\ 195 void *class_addr; \n\ 196 void *sel_addr; \n\ 197 void *impl_addr; \n\ 198 }; \n\ 199 \n\ 200 struct __lldb_objc_class { \n\ 201 void *isa; \n\ 202 void *super_ptr; \n\ 203 }; \n\ 204 struct __lldb_objc_super { \n\ 205 void *reciever; \n\ 206 struct __lldb_objc_class *class_ptr; \n\ 207 }; \n\ 208 struct __lldb_msg_ref { \n\ 209 void *dont_know; \n\ 210 void *sel; \n\ 211 }; \n\ 212 \n\ 213 struct __lldb_imp_return_struct return_struct; \n\ 214 \n\ 215 if (debug) \n\ 216 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ 217 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 218 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ 219 if (is_super) \n\ 220 { \n\ 221 if (is_super2) \n\ 222 { \n\ 223 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ 224 } \n\ 225 else \n\ 226 { \n\ 227 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ 228 } \n\ 229 } \n\ 230 else \n\ 231 { \n\ 232 // This code seems a little funny, but has its reasons... \n\ 233 // The call to [object class] is here because if this is a class, and has not been called into \n\ 234 // yet, we need to do something to force the class to initialize itself. \n\ 235 // Then the call to object_getClass will actually return the correct class, either the class \n\ 236 // if object is a class instance, or the meta-class if it is a class pointer. \n\ 237 void *class_ptr = (void *) [(id) object class]; \n\ 238 return_struct.class_addr = (id) object_getClass((id) object); \n\ 239 if (debug) \n\ 240 { \n\ 241 if (class_ptr == object) \n\ 242 { \n\ 243 printf (\"Found a class object, need to return the meta class %p -> %p\\n\", \n\ 244 class_ptr, return_struct.class_addr); \n\ 245 } \n\ 246 else \n\ 247 { \n\ 248 printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ 249 class_ptr, return_struct.class_addr); \n\ 250 } \n\ 251 } \n\ 252 } \n\ 253 \n\ 254 if (is_fixup) \n\ 255 { \n\ 256 if (is_fixed) \n\ 257 { \n\ 258 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 259 } \n\ 260 else \n\ 261 { \n\ 262 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 263 return_struct.sel_addr = sel_getUid (sel_name); \n\ 264 if (debug) \n\ 265 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\ 266 return_struct.sel_addr, sel_name); \n\ 267 } \n\ 268 } \n\ 269 else \n\ 270 { \n\ 271 return_struct.sel_addr = sel; \n\ 272 } \n\ 273 \n\ 274 return_struct.impl_addr = \n\ 275 class_getMethodImplementation (return_struct.class_addr, \n\ 276 return_struct.sel_addr); \n\ 277 if (debug) \n\ 278 printf (\"\\n*** Returning implementation: 0x%p.\\n\", \n\ 279 return_struct.impl_addr); \n\ 280 \n\ 281 return return_struct.impl_addr; \n\ 282} \n\ 283"; 284 285AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion( 286 AppleObjCVTables *owner, lldb::addr_t header_addr) 287 : m_valid(true), m_owner(owner), m_header_addr(header_addr), 288 m_code_start_addr(0), m_code_end_addr(0), m_next_region(0) { 289 SetUpRegion(); 290} 291 292AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() {} 293 294void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() { 295 // The header looks like: 296 // 297 // uint16_t headerSize 298 // uint16_t descSize 299 // uint32_t descCount 300 // void * next 301 // 302 // First read in the header: 303 304 char memory_buffer[16]; 305 ProcessSP process_sp = m_owner->GetProcessSP(); 306 if (!process_sp) 307 return; 308 DataExtractor data(memory_buffer, sizeof(memory_buffer), 309 process_sp->GetByteOrder(), 310 process_sp->GetAddressByteSize()); 311 size_t actual_size = 8 + process_sp->GetAddressByteSize(); 312 Status error; 313 size_t bytes_read = 314 process_sp->ReadMemory(m_header_addr, memory_buffer, actual_size, error); 315 if (bytes_read != actual_size) { 316 m_valid = false; 317 return; 318 } 319 320 lldb::offset_t offset = 0; 321 const uint16_t header_size = data.GetU16(&offset); 322 const uint16_t descriptor_size = data.GetU16(&offset); 323 const size_t num_descriptors = data.GetU32(&offset); 324 325 m_next_region = data.GetPointer(&offset); 326 327 // If the header size is 0, that means we've come in too early before this 328 // data is set up. 329 // Set ourselves as not valid, and continue. 330 if (header_size == 0 || num_descriptors == 0) { 331 m_valid = false; 332 return; 333 } 334 335 // Now read in all the descriptors: 336 // The descriptor looks like: 337 // 338 // uint32_t offset 339 // uint32_t flags 340 // 341 // Where offset is either 0 - in which case it is unused, or it is 342 // the offset of the vtable code from the beginning of the 343 // descriptor record. Below, we'll convert that into an absolute 344 // code address, since I don't want to have to compute it over and 345 // over. 346 347 // Ingest the whole descriptor array: 348 const lldb::addr_t desc_ptr = m_header_addr + header_size; 349 const size_t desc_array_size = num_descriptors * descriptor_size; 350 DataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0')); 351 uint8_t *dst = (uint8_t *)data_sp->GetBytes(); 352 353 DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(), 354 process_sp->GetAddressByteSize()); 355 bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error); 356 if (bytes_read != desc_array_size) { 357 m_valid = false; 358 return; 359 } 360 361 // The actual code for the vtables will be laid out consecutively, so I also 362 // compute the start and end of the whole code block. 363 364 offset = 0; 365 m_code_start_addr = 0; 366 m_code_end_addr = 0; 367 368 for (size_t i = 0; i < num_descriptors; i++) { 369 lldb::addr_t start_offset = offset; 370 uint32_t voffset = desc_extractor.GetU32(&offset); 371 uint32_t flags = desc_extractor.GetU32(&offset); 372 lldb::addr_t code_addr = desc_ptr + start_offset + voffset; 373 m_descriptors.push_back(VTableDescriptor(flags, code_addr)); 374 375 if (m_code_start_addr == 0 || code_addr < m_code_start_addr) 376 m_code_start_addr = code_addr; 377 if (code_addr > m_code_end_addr) 378 m_code_end_addr = code_addr; 379 380 offset = start_offset + descriptor_size; 381 } 382 // Finally, a little bird told me that all the vtable code blocks 383 // are the same size. Let's compute the blocks and if they are all 384 // the same add the size to the code end address: 385 lldb::addr_t code_size = 0; 386 bool all_the_same = true; 387 for (size_t i = 0; i < num_descriptors - 1; i++) { 388 lldb::addr_t this_size = 389 m_descriptors[i + 1].code_start - m_descriptors[i].code_start; 390 if (code_size == 0) 391 code_size = this_size; 392 else { 393 if (this_size != code_size) 394 all_the_same = false; 395 if (this_size > code_size) 396 code_size = this_size; 397 } 398 } 399 if (all_the_same) 400 m_code_end_addr += code_size; 401} 402 403bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion:: 404 AddressInRegion(lldb::addr_t addr, uint32_t &flags) { 405 if (!IsValid()) 406 return false; 407 408 if (addr < m_code_start_addr || addr > m_code_end_addr) 409 return false; 410 411 std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end(); 412 for (pos = m_descriptors.begin(); pos != end; pos++) { 413 if (addr <= (*pos).code_start) { 414 flags = (*pos).flags; 415 return true; 416 } 417 } 418 return false; 419} 420 421void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump( 422 Stream &s) { 423 s.Printf("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64 424 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n", 425 m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); 426 size_t num_elements = m_descriptors.size(); 427 for (size_t i = 0; i < num_elements; i++) { 428 s.Indent(); 429 s.Printf("Code start: 0x%" PRIx64 " Flags: %d\n", 430 m_descriptors[i].code_start, m_descriptors[i].flags); 431 } 432} 433 434AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables( 435 const ProcessSP &process_sp, const ModuleSP &objc_module_sp) 436 : m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS), 437 m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID), 438 m_objc_module_sp(objc_module_sp) { 439 if (process_sp) 440 m_process_wp = process_sp; 441} 442 443AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() { 444 ProcessSP process_sp = GetProcessSP(); 445 if (process_sp) { 446 if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) 447 process_sp->GetTarget().RemoveBreakpointByID(m_trampolines_changed_bp_id); 448 } 449} 450 451bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() { 452 if (m_trampoline_header != LLDB_INVALID_ADDRESS) 453 return true; 454 455 ProcessSP process_sp = GetProcessSP(); 456 if (process_sp) { 457 Target &target = process_sp->GetTarget(); 458 459 const ModuleList &target_modules = target.GetImages(); 460 std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex()); 461 size_t num_modules = target_modules.GetSize(); 462 if (!m_objc_module_sp) { 463 for (size_t i = 0; i < num_modules; i++) { 464 if (process_sp->GetObjCLanguageRuntime()->IsModuleObjCLibrary( 465 target_modules.GetModuleAtIndexUnlocked(i))) { 466 m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i); 467 break; 468 } 469 } 470 } 471 472 if (m_objc_module_sp) { 473 ConstString trampoline_name("gdb_objc_trampolines"); 474 const Symbol *trampoline_symbol = 475 m_objc_module_sp->FindFirstSymbolWithNameAndType(trampoline_name, 476 eSymbolTypeData); 477 if (trampoline_symbol != NULL) { 478 m_trampoline_header = trampoline_symbol->GetLoadAddress(&target); 479 if (m_trampoline_header == LLDB_INVALID_ADDRESS) 480 return false; 481 482 // Next look up the "changed" symbol and set a breakpoint on that... 483 ConstString changed_name("gdb_objc_trampolines_changed"); 484 const Symbol *changed_symbol = 485 m_objc_module_sp->FindFirstSymbolWithNameAndType(changed_name, 486 eSymbolTypeCode); 487 if (changed_symbol != NULL) { 488 const Address changed_symbol_addr = changed_symbol->GetAddress(); 489 if (!changed_symbol_addr.IsValid()) 490 return false; 491 492 lldb::addr_t changed_addr = 493 changed_symbol_addr.GetOpcodeLoadAddress(&target); 494 if (changed_addr != LLDB_INVALID_ADDRESS) { 495 BreakpointSP trampolines_changed_bp_sp = 496 target.CreateBreakpoint(changed_addr, true, false); 497 if (trampolines_changed_bp_sp) { 498 m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); 499 trampolines_changed_bp_sp->SetCallback(RefreshTrampolines, this, 500 true); 501 trampolines_changed_bp_sp->SetBreakpointKind( 502 "objc-trampolines-changed"); 503 return true; 504 } 505 } 506 } 507 } 508 } 509 } 510 return false; 511} 512 513bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines( 514 void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id, 515 lldb::user_id_t break_loc_id) { 516 AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton; 517 if (vtable_handler->InitializeVTableSymbols()) { 518 // The Update function is called with the address of an added region. So we 519 // grab that address, and 520 // feed it into ReadRegions. Of course, our friend the ABI will get the 521 // values for us. 522 ExecutionContext exe_ctx(context->exe_ctx_ref); 523 Process *process = exe_ctx.GetProcessPtr(); 524 const ABI *abi = process->GetABI().get(); 525 526 ClangASTContext *clang_ast_context = 527 process->GetTarget().GetScratchClangASTContext(); 528 ValueList argument_values; 529 Value input_value; 530 CompilerType clang_void_ptr_type = 531 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 532 533 input_value.SetValueType(Value::eValueTypeScalar); 534 // input_value.SetContext (Value::eContextTypeClangType, 535 // clang_void_ptr_type); 536 input_value.SetCompilerType(clang_void_ptr_type); 537 argument_values.PushValue(input_value); 538 539 bool success = 540 abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values); 541 if (!success) 542 return false; 543 544 // Now get a pointer value from the zeroth argument. 545 Status error; 546 DataExtractor data; 547 error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data, 548 0, NULL); 549 lldb::offset_t offset = 0; 550 lldb::addr_t region_addr = data.GetPointer(&offset); 551 552 if (region_addr != 0) 553 vtable_handler->ReadRegions(region_addr); 554 } 555 return false; 556} 557 558bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() { 559 // The no argument version reads the start region from the value of 560 // the gdb_regions_header, and gets started from there. 561 562 m_regions.clear(); 563 if (!InitializeVTableSymbols()) 564 return false; 565 Status error; 566 ProcessSP process_sp = GetProcessSP(); 567 if (process_sp) { 568 lldb::addr_t region_addr = 569 process_sp->ReadPointerFromMemory(m_trampoline_header, error); 570 if (error.Success()) 571 return ReadRegions(region_addr); 572 } 573 return false; 574} 575 576bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions( 577 lldb::addr_t region_addr) { 578 ProcessSP process_sp = GetProcessSP(); 579 if (!process_sp) 580 return false; 581 582 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 583 584 // We aren't starting at the trampoline symbol. 585 InitializeVTableSymbols(); 586 lldb::addr_t next_region = region_addr; 587 588 // Read in the sizes of the headers. 589 while (next_region != 0) { 590 m_regions.push_back(VTableRegion(this, next_region)); 591 if (!m_regions.back().IsValid()) { 592 m_regions.clear(); 593 return false; 594 } 595 if (log) { 596 StreamString s; 597 m_regions.back().Dump(s); 598 log->Printf("Read vtable region: \n%s", s.GetData()); 599 } 600 601 next_region = m_regions.back().GetNextRegionAddr(); 602 } 603 604 return true; 605} 606 607bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables( 608 lldb::addr_t addr, uint32_t &flags) { 609 region_collection::iterator pos, end = m_regions.end(); 610 for (pos = m_regions.begin(); pos != end; pos++) { 611 if ((*pos).AddressInRegion(addr, flags)) 612 return true; 613 } 614 return false; 615} 616 617const AppleObjCTrampolineHandler::DispatchFunction 618 AppleObjCTrampolineHandler::g_dispatch_functions[] = { 619 // NAME STRET SUPER SUPER2 FIXUP TYPE 620 {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone}, 621 {"objc_msgSend_fixup", false, false, false, 622 DispatchFunction::eFixUpToFix}, 623 {"objc_msgSend_fixedup", false, false, false, 624 DispatchFunction::eFixUpFixed}, 625 {"objc_msgSend_stret", true, false, false, 626 DispatchFunction::eFixUpNone}, 627 {"objc_msgSend_stret_fixup", true, false, false, 628 DispatchFunction::eFixUpToFix}, 629 {"objc_msgSend_stret_fixedup", true, false, false, 630 DispatchFunction::eFixUpFixed}, 631 {"objc_msgSend_fpret", false, false, false, 632 DispatchFunction::eFixUpNone}, 633 {"objc_msgSend_fpret_fixup", false, false, false, 634 DispatchFunction::eFixUpToFix}, 635 {"objc_msgSend_fpret_fixedup", false, false, false, 636 DispatchFunction::eFixUpFixed}, 637 {"objc_msgSend_fp2ret", false, false, true, 638 DispatchFunction::eFixUpNone}, 639 {"objc_msgSend_fp2ret_fixup", false, false, true, 640 DispatchFunction::eFixUpToFix}, 641 {"objc_msgSend_fp2ret_fixedup", false, false, true, 642 DispatchFunction::eFixUpFixed}, 643 {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone}, 644 {"objc_msgSendSuper_stret", true, true, false, 645 DispatchFunction::eFixUpNone}, 646 {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone}, 647 {"objc_msgSendSuper2_fixup", false, true, true, 648 DispatchFunction::eFixUpToFix}, 649 {"objc_msgSendSuper2_fixedup", false, true, true, 650 DispatchFunction::eFixUpFixed}, 651 {"objc_msgSendSuper2_stret", true, true, true, 652 DispatchFunction::eFixUpNone}, 653 {"objc_msgSendSuper2_stret_fixup", true, true, true, 654 DispatchFunction::eFixUpToFix}, 655 {"objc_msgSendSuper2_stret_fixedup", true, true, true, 656 DispatchFunction::eFixUpFixed}, 657}; 658 659AppleObjCTrampolineHandler::AppleObjCTrampolineHandler( 660 const ProcessSP &process_sp, const ModuleSP &objc_module_sp) 661 : m_process_wp(), m_objc_module_sp(objc_module_sp), 662 m_lookup_implementation_function_code(nullptr), 663 m_impl_fn_addr(LLDB_INVALID_ADDRESS), 664 m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS), 665 m_msg_forward_addr(LLDB_INVALID_ADDRESS) { 666 if (process_sp) 667 m_process_wp = process_sp; 668 // Look up the known resolution functions: 669 670 ConstString get_impl_name("class_getMethodImplementation"); 671 ConstString get_impl_stret_name("class_getMethodImplementation_stret"); 672 ConstString msg_forward_name("_objc_msgForward"); 673 ConstString msg_forward_stret_name("_objc_msgForward_stret"); 674 675 Target *target = process_sp ? &process_sp->GetTarget() : NULL; 676 const Symbol *class_getMethodImplementation = 677 m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_name, 678 eSymbolTypeCode); 679 const Symbol *class_getMethodImplementation_stret = 680 m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_stret_name, 681 eSymbolTypeCode); 682 const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType( 683 msg_forward_name, eSymbolTypeCode); 684 const Symbol *msg_forward_stret = 685 m_objc_module_sp->FindFirstSymbolWithNameAndType(msg_forward_stret_name, 686 eSymbolTypeCode); 687 688 if (class_getMethodImplementation) 689 m_impl_fn_addr = 690 class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress( 691 target); 692 if (class_getMethodImplementation_stret) 693 m_impl_stret_fn_addr = 694 class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress( 695 target); 696 if (msg_forward) 697 m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target); 698 if (msg_forward_stret) 699 m_msg_forward_stret_addr = 700 msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target); 701 702 // FIXME: Do some kind of logging here. 703 if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) { 704 // If we can't even find the ordinary get method implementation function, 705 // then we aren't going to be able to 706 // step through any method dispatches. Warn to that effect and get out of 707 // here. 708 if (process_sp->CanJIT()) { 709 process_sp->GetTarget().GetDebugger().GetErrorFile()->Printf( 710 "Could not find implementation lookup function \"%s\"" 711 " step in through ObjC method dispatch will not work.\n", 712 get_impl_name.AsCString()); 713 } 714 return; 715 } else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) { 716 // It there is no stret return lookup function, assume that it is the same 717 // as the straight lookup: 718 m_impl_stret_fn_addr = m_impl_fn_addr; 719 // Also we will use the version of the lookup code that doesn't rely on the 720 // stret version of the function. 721 m_lookup_implementation_function_code = 722 g_lookup_implementation_no_stret_function_code; 723 } else { 724 m_lookup_implementation_function_code = 725 g_lookup_implementation_with_stret_function_code; 726 } 727 728 // Look up the addresses for the objc dispatch functions and cache 729 // them. For now I'm inspecting the symbol names dynamically to 730 // figure out how to dispatch to them. If it becomes more 731 // complicated than this we can turn the g_dispatch_functions char * 732 // array into a template table, and populate the DispatchFunction 733 // map from there. 734 735 for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) { 736 ConstString name_const_str(g_dispatch_functions[i].name); 737 const Symbol *msgSend_symbol = 738 m_objc_module_sp->FindFirstSymbolWithNameAndType(name_const_str, 739 eSymbolTypeCode); 740 if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) { 741 // FIXME: Make g_dispatch_functions static table of 742 // DispatchFunctions, and have the map be address->index. 743 // Problem is we also need to lookup the dispatch function. For 744 // now we could have a side table of stret & non-stret dispatch 745 // functions. If that's as complex as it gets, we're fine. 746 747 lldb::addr_t sym_addr = 748 msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target); 749 750 m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i)); 751 } 752 } 753 754 // Build our vtable dispatch handler here: 755 m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); 756 if (m_vtables_ap.get()) 757 m_vtables_ap->ReadRegions(); 758} 759 760lldb::addr_t 761AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread, 762 ValueList &dispatch_values) { 763 ThreadSP thread_sp(thread.shared_from_this()); 764 ExecutionContext exe_ctx(thread_sp); 765 DiagnosticManager diagnostics; 766 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 767 768 lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; 769 FunctionCaller *impl_function_caller = nullptr; 770 771 // Scope for mutex locker: 772 { 773 std::lock_guard<std::mutex> guard(m_impl_function_mutex); 774 775 // First stage is to make the ClangUtility to hold our injected function: 776 777 if (!m_impl_code.get()) { 778 if (m_lookup_implementation_function_code != NULL) { 779 Status error; 780 m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage( 781 m_lookup_implementation_function_code, eLanguageTypeObjC, 782 g_lookup_implementation_function_name, error)); 783 if (error.Fail()) { 784 if (log) 785 log->Printf( 786 "Failed to get Utility Function for implementation lookup: %s.", 787 error.AsCString()); 788 m_impl_code.reset(); 789 return args_addr; 790 } 791 792 if (!m_impl_code->Install(diagnostics, exe_ctx)) { 793 if (log) { 794 log->Printf("Failed to install implementation lookup."); 795 diagnostics.Dump(log); 796 } 797 m_impl_code.reset(); 798 return args_addr; 799 } 800 } else { 801 if (log) 802 log->Printf("No method lookup implementation code."); 803 return LLDB_INVALID_ADDRESS; 804 } 805 806 // Next make the runner function for our implementation utility function. 807 ClangASTContext *clang_ast_context = 808 thread.GetProcess()->GetTarget().GetScratchClangASTContext(); 809 CompilerType clang_void_ptr_type = 810 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 811 Status error; 812 813 impl_function_caller = m_impl_code->MakeFunctionCaller( 814 clang_void_ptr_type, dispatch_values, thread_sp, error); 815 if (error.Fail()) { 816 if (log) 817 log->Printf( 818 "Error getting function caller for dispatch lookup: \"%s\".", 819 error.AsCString()); 820 return args_addr; 821 } 822 } else { 823 impl_function_caller = m_impl_code->GetFunctionCaller(); 824 } 825 } 826 827 diagnostics.Clear(); 828 829 // Now write down the argument values for this particular call. 830 // This looks like it might be a race condition if other threads 831 // were calling into here, but actually it isn't because we allocate 832 // a new args structure for this call by passing args_addr = 833 // LLDB_INVALID_ADDRESS... 834 835 if (!impl_function_caller->WriteFunctionArguments( 836 exe_ctx, args_addr, dispatch_values, diagnostics)) { 837 if (log) { 838 log->Printf("Error writing function arguments."); 839 diagnostics.Dump(log); 840 } 841 return args_addr; 842 } 843 844 return args_addr; 845} 846 847ThreadPlanSP 848AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread, 849 bool stop_others) { 850 ThreadPlanSP ret_plan_sp; 851 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); 852 853 DispatchFunction this_dispatch; 854 bool found_it = false; 855 856 // First step is to look and see if we are in one of the known ObjC 857 // dispatch functions. We've already compiled a table of same, so 858 // consult it. 859 860 MsgsendMap::iterator pos; 861 pos = m_msgSend_map.find(curr_pc); 862 if (pos != m_msgSend_map.end()) { 863 this_dispatch = g_dispatch_functions[(*pos).second]; 864 found_it = true; 865 } 866 867 // Next check to see if we are in a vtable region: 868 869 if (!found_it) { 870 uint32_t flags; 871 if (m_vtables_ap.get()) { 872 found_it = m_vtables_ap->IsAddressInVTables(curr_pc, flags); 873 if (found_it) { 874 this_dispatch.name = "vtable"; 875 this_dispatch.stret_return = 876 (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == 877 AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; 878 this_dispatch.is_super = false; 879 this_dispatch.is_super2 = false; 880 this_dispatch.fixedup = DispatchFunction::eFixUpFixed; 881 } 882 } 883 } 884 885 if (found_it) { 886 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 887 888 // We are decoding a method dispatch. First job is to pull the 889 // arguments out: 890 891 lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); 892 893 const ABI *abi = NULL; 894 ProcessSP process_sp(thread.CalculateProcess()); 895 if (process_sp) 896 abi = process_sp->GetABI().get(); 897 if (abi == NULL) 898 return ret_plan_sp; 899 900 TargetSP target_sp(thread.CalculateTarget()); 901 902 ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext(); 903 ValueList argument_values; 904 Value void_ptr_value; 905 CompilerType clang_void_ptr_type = 906 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 907 void_ptr_value.SetValueType(Value::eValueTypeScalar); 908 // void_ptr_value.SetContext (Value::eContextTypeClangType, 909 // clang_void_ptr_type); 910 void_ptr_value.SetCompilerType(clang_void_ptr_type); 911 912 int obj_index; 913 int sel_index; 914 915 // If this is a struct return dispatch, then the first argument is 916 // the return struct pointer, and the object is the second, and 917 // the selector is the third. Otherwise the object is the first 918 // and the selector the second. 919 if (this_dispatch.stret_return) { 920 obj_index = 1; 921 sel_index = 2; 922 argument_values.PushValue(void_ptr_value); 923 argument_values.PushValue(void_ptr_value); 924 argument_values.PushValue(void_ptr_value); 925 } else { 926 obj_index = 0; 927 sel_index = 1; 928 argument_values.PushValue(void_ptr_value); 929 argument_values.PushValue(void_ptr_value); 930 } 931 932 bool success = abi->GetArgumentValues(thread, argument_values); 933 if (!success) 934 return ret_plan_sp; 935 936 lldb::addr_t obj_addr = 937 argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong(); 938 if (obj_addr == 0x0) { 939 if (log) 940 log->Printf( 941 "Asked to step to dispatch to nil object, returning empty plan."); 942 return ret_plan_sp; 943 } 944 945 ExecutionContext exe_ctx(thread.shared_from_this()); 946 Process *process = exe_ctx.GetProcessPtr(); 947 // isa_addr will store the class pointer that the method is being 948 // dispatched to - so either the class directly or the super class 949 // if this is one of the objc_msgSendSuper flavors. That's mostly 950 // used to look up the class/selector pair in our cache. 951 952 lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; 953 lldb::addr_t sel_addr = 954 argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); 955 956 // Figure out the class this is being dispatched to and see if 957 // we've already cached this method call, If so we can push a 958 // run-to-address plan directly. Otherwise we have to figure out 959 // where the implementation lives. 960 961 if (this_dispatch.is_super) { 962 if (this_dispatch.is_super2) { 963 // In the objc_msgSendSuper2 case, we don't get the object 964 // directly, we get a structure containing the object and the 965 // class to which the super message is being sent. So we need 966 // to dig the super out of the class and use that. 967 968 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 969 super_value.GetScalar() += process->GetAddressByteSize(); 970 super_value.ResolveValue(&exe_ctx); 971 972 if (super_value.GetScalar().IsValid()) { 973 974 // isa_value now holds the class pointer. The second word of the 975 // class pointer is the super-class pointer: 976 super_value.GetScalar() += process->GetAddressByteSize(); 977 super_value.ResolveValue(&exe_ctx); 978 if (super_value.GetScalar().IsValid()) 979 isa_addr = super_value.GetScalar().ULongLong(); 980 else { 981 if (log) 982 log->Printf("Failed to extract the super class value from the " 983 "class in objc_super."); 984 } 985 } else { 986 if (log) 987 log->Printf("Failed to extract the class value from objc_super."); 988 } 989 } else { 990 // In the objc_msgSendSuper case, we don't get the object 991 // directly, we get a two element structure containing the 992 // object and the super class to which the super message is 993 // being sent. So the class we want is the second element of 994 // this structure. 995 996 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 997 super_value.GetScalar() += process->GetAddressByteSize(); 998 super_value.ResolveValue(&exe_ctx); 999 1000 if (super_value.GetScalar().IsValid()) { 1001 isa_addr = super_value.GetScalar().ULongLong(); 1002 } else { 1003 if (log) 1004 log->Printf("Failed to extract the class value from objc_super."); 1005 } 1006 } 1007 } else { 1008 // In the direct dispatch case, the object->isa is the class pointer we 1009 // want. 1010 1011 // This is a little cheesy, but since object->isa is the first field, 1012 // making the object value a load address value and resolving it will get 1013 // the pointer sized data pointed to by that value... 1014 1015 // Note, it isn't a fatal error not to be able to get the 1016 // address from the object, since this might be a "tagged 1017 // pointer" which isn't a real object, but rather some word 1018 // length encoded dingus. 1019 1020 Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); 1021 1022 isa_value.SetValueType(Value::eValueTypeLoadAddress); 1023 isa_value.ResolveValue(&exe_ctx); 1024 if (isa_value.GetScalar().IsValid()) { 1025 isa_addr = isa_value.GetScalar().ULongLong(); 1026 } else { 1027 if (log) 1028 log->Printf("Failed to extract the isa value from object."); 1029 } 1030 } 1031 1032 // Okay, we've got the address of the class for which we're resolving this, 1033 // let's see if it's in our cache: 1034 lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; 1035 1036 if (isa_addr != LLDB_INVALID_ADDRESS) { 1037 if (log) { 1038 log->Printf("Resolving call for class - 0x%" PRIx64 1039 " and selector - 0x%" PRIx64, 1040 isa_addr, sel_addr); 1041 } 1042 ObjCLanguageRuntime *objc_runtime = 1043 thread.GetProcess()->GetObjCLanguageRuntime(); 1044 assert(objc_runtime != NULL); 1045 1046 impl_addr = objc_runtime->LookupInMethodCache(isa_addr, sel_addr); 1047 } 1048 1049 if (impl_addr != LLDB_INVALID_ADDRESS) { 1050 // Yup, it was in the cache, so we can run to that address directly. 1051 1052 if (log) 1053 log->Printf("Found implementation address in cache: 0x%" PRIx64, 1054 impl_addr); 1055 1056 ret_plan_sp.reset( 1057 new ThreadPlanRunToAddress(thread, impl_addr, stop_others)); 1058 } else { 1059 // We haven't seen this class/selector pair yet. Look it up. 1060 StreamString errors; 1061 Address impl_code_address; 1062 1063 ValueList dispatch_values; 1064 1065 // We've will inject a little function in the target that takes the 1066 // object, selector and some flags, 1067 // and figures out the implementation. Looks like: 1068 // void *__lldb_objc_find_implementation_for_selector (void *object, 1069 // void *sel, 1070 // int is_stret, 1071 // int is_super, 1072 // int is_super2, 1073 // int is_fixup, 1074 // int is_fixed, 1075 // int debug) 1076 // So set up the arguments for that call. 1077 1078 dispatch_values.PushValue(*(argument_values.GetValueAtIndex(obj_index))); 1079 dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index))); 1080 1081 Value flag_value; 1082 CompilerType clang_int_type = 1083 clang_ast_context->GetBuiltinTypeForEncodingAndBitSize( 1084 lldb::eEncodingSint, 32); 1085 flag_value.SetValueType(Value::eValueTypeScalar); 1086 // flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); 1087 flag_value.SetCompilerType(clang_int_type); 1088 1089 if (this_dispatch.stret_return) 1090 flag_value.GetScalar() = 1; 1091 else 1092 flag_value.GetScalar() = 0; 1093 dispatch_values.PushValue(flag_value); 1094 1095 if (this_dispatch.is_super) 1096 flag_value.GetScalar() = 1; 1097 else 1098 flag_value.GetScalar() = 0; 1099 dispatch_values.PushValue(flag_value); 1100 1101 if (this_dispatch.is_super2) 1102 flag_value.GetScalar() = 1; 1103 else 1104 flag_value.GetScalar() = 0; 1105 dispatch_values.PushValue(flag_value); 1106 1107 switch (this_dispatch.fixedup) { 1108 case DispatchFunction::eFixUpNone: 1109 flag_value.GetScalar() = 0; 1110 dispatch_values.PushValue(flag_value); 1111 dispatch_values.PushValue(flag_value); 1112 break; 1113 case DispatchFunction::eFixUpFixed: 1114 flag_value.GetScalar() = 1; 1115 dispatch_values.PushValue(flag_value); 1116 flag_value.GetScalar() = 1; 1117 dispatch_values.PushValue(flag_value); 1118 break; 1119 case DispatchFunction::eFixUpToFix: 1120 flag_value.GetScalar() = 1; 1121 dispatch_values.PushValue(flag_value); 1122 flag_value.GetScalar() = 0; 1123 dispatch_values.PushValue(flag_value); 1124 break; 1125 } 1126 if (log && log->GetVerbose()) 1127 flag_value.GetScalar() = 1; 1128 else 1129 flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. 1130 dispatch_values.PushValue(flag_value); 1131 1132 // The step through code might have to fill in the cache, so it 1133 // is not safe to run only one thread. So we override the 1134 // stop_others value passed in to us here: 1135 const bool trampoline_stop_others = false; 1136 ret_plan_sp.reset(new AppleThreadPlanStepThroughObjCTrampoline( 1137 thread, this, dispatch_values, isa_addr, sel_addr, 1138 trampoline_stop_others)); 1139 if (log) { 1140 StreamString s; 1141 ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); 1142 log->Printf("Using ObjC step plan: %s.\n", s.GetData()); 1143 } 1144 } 1145 } 1146 1147 return ret_plan_sp; 1148} 1149 1150FunctionCaller * 1151AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() { 1152 return m_impl_code->GetFunctionCaller(); 1153} 1154