AppleObjCTrampolineHandler.cpp revision 355940
1//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++ 2//-*-===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#include "AppleObjCTrampolineHandler.h" 11#include "AppleThreadPlanStepThroughObjCTrampoline.h" 12 13#include "lldb/Breakpoint/StoppointCallbackContext.h" 14#include "lldb/Core/Debugger.h" 15#include "lldb/Core/Module.h" 16#include "lldb/Core/StreamFile.h" 17#include "lldb/Core/Value.h" 18#include "lldb/Expression/DiagnosticManager.h" 19#include "lldb/Expression/FunctionCaller.h" 20#include "lldb/Expression/UserExpression.h" 21#include "lldb/Expression/UtilityFunction.h" 22#include "lldb/Symbol/ClangASTContext.h" 23#include "lldb/Symbol/Symbol.h" 24#include "lldb/Target/ABI.h" 25#include "lldb/Target/ExecutionContext.h" 26#include "lldb/Target/Process.h" 27#include "lldb/Target/RegisterContext.h" 28#include "lldb/Target/Target.h" 29#include "lldb/Target/Thread.h" 30#include "lldb/Target/ThreadPlanRunToAddress.h" 31#include "lldb/Utility/ConstString.h" 32#include "lldb/Utility/FileSpec.h" 33#include "lldb/Utility/Log.h" 34 35#include "llvm/ADT/STLExtras.h" 36 37#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h" 38 39#include <memory> 40 41using namespace lldb; 42using namespace lldb_private; 43 44const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = 45 "__lldb_objc_find_implementation_for_selector"; 46const char *AppleObjCTrampolineHandler:: 47 g_lookup_implementation_with_stret_function_code = 48 " \n\ 49extern \"C\" \n\ 50{ \n\ 51 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 52 extern void *class_getMethodImplementation_stret(void *objc_class, \n\ 53 void *sel); \n\ 54 extern void * object_getClass (id object); \n\ 55 extern void * sel_getUid(char *name); \n\ 56 extern int printf(const char *format, ...); \n\ 57} \n\ 58extern \"C\" void * __lldb_objc_find_implementation_for_selector ( \n\ 59 void *object, \n\ 60 void *sel, \n\ 61 int is_stret, \n\ 62 int is_super, \n\ 63 int is_super2, \n\ 64 int is_fixup, \n\ 65 int is_fixed, \n\ 66 int debug) \n\ 67{ \n\ 68 struct __lldb_imp_return_struct \n\ 69 { \n\ 70 void *class_addr; \n\ 71 void *sel_addr; \n\ 72 void *impl_addr; \n\ 73 }; \n\ 74 \n\ 75 struct __lldb_objc_class { \n\ 76 void *isa; \n\ 77 void *super_ptr; \n\ 78 }; \n\ 79 struct __lldb_objc_super { \n\ 80 void *receiver; \n\ 81 struct __lldb_objc_class *class_ptr; \n\ 82 }; \n\ 83 struct __lldb_msg_ref { \n\ 84 void *dont_know; \n\ 85 void *sel; \n\ 86 }; \n\ 87 \n\ 88 struct __lldb_imp_return_struct return_struct; \n\ 89 \n\ 90 if (debug) \n\ 91 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \"\n\ 92 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 93 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed);\n\ 94 if (is_super) \n\ 95 { \n\ 96 if (is_super2) \n\ 97 { \n\ 98 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr;\n\ 99 } \n\ 100 else \n\ 101 { \n\ 102 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;\n\ 103 } \n\ 104 } \n\ 105 else \n\ 106 { \n\ 107 // This code seems a little funny, but has its reasons... \n\ 108 \n\ 109 // The call to [object class] is here because if this is a \n\ 110 // class, and has not been called into yet, we need to do \n\ 111 // something to force the class to initialize itself. \n\ 112 // Then the call to object_getClass will actually return the \n\ 113 // correct class, either the class if object is a class \n\ 114 // instance, or the meta-class if it is a class pointer. \n\ 115 void *class_ptr = (void *) [(id) object class]; \n\ 116 return_struct.class_addr = (id) object_getClass((id) object); \n\ 117 if (debug) \n\ 118 { \n\ 119 if (class_ptr == object) \n\ 120 { \n\ 121 printf (\"Found a class object, need to use the meta class %p -> %p\\n\",\n\ 122 class_ptr, return_struct.class_addr); \n\ 123 } \n\ 124 else \n\ 125 { \n\ 126 printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ 127 class_ptr, return_struct.class_addr); \n\ 128 } \n\ 129 } \n\ 130 } \n\ 131 \n\ 132 if (is_fixup) \n\ 133 { \n\ 134 if (is_fixed) \n\ 135 { \n\ 136 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 137 } \n\ 138 else \n\ 139 { \n\ 140 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 141 return_struct.sel_addr = sel_getUid (sel_name); \n\ 142 if (debug) \n\ 143 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\ 144 return_struct.sel_addr, sel_name); \n\ 145 } \n\ 146 } \n\ 147 else \n\ 148 { \n\ 149 return_struct.sel_addr = sel; \n\ 150 } \n\ 151 \n\ 152 if (is_stret) \n\ 153 { \n\ 154 return_struct.impl_addr = \n\ 155 class_getMethodImplementation_stret (return_struct.class_addr, \n\ 156 return_struct.sel_addr); \n\ 157 } \n\ 158 else \n\ 159 { \n\ 160 return_struct.impl_addr = \n\ 161 class_getMethodImplementation (return_struct.class_addr, \n\ 162 return_struct.sel_addr); \n\ 163 } \n\ 164 if (debug) \n\ 165 printf (\"\\n*** Returning implementation: %p.\\n\", \n\ 166 return_struct.impl_addr); \n\ 167 \n\ 168 return return_struct.impl_addr; \n\ 169} \n\ 170"; 171const char * 172 AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code = 173 " \n\ 174extern \"C\" \n\ 175{ \n\ 176 extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ 177 extern void * object_getClass (id object); \n\ 178 extern void * sel_getUid(char *name); \n\ 179 extern int printf(const char *format, ...); \n\ 180} \n\ 181extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ 182 void *sel, \n\ 183 int is_stret, \n\ 184 int is_super, \n\ 185 int is_super2, \n\ 186 int is_fixup, \n\ 187 int is_fixed, \n\ 188 int debug) \n\ 189{ \n\ 190 struct __lldb_imp_return_struct \n\ 191 { \n\ 192 void *class_addr; \n\ 193 void *sel_addr; \n\ 194 void *impl_addr; \n\ 195 }; \n\ 196 \n\ 197 struct __lldb_objc_class { \n\ 198 void *isa; \n\ 199 void *super_ptr; \n\ 200 }; \n\ 201 struct __lldb_objc_super { \n\ 202 void *receiver; \n\ 203 struct __lldb_objc_class *class_ptr; \n\ 204 }; \n\ 205 struct __lldb_msg_ref { \n\ 206 void *dont_know; \n\ 207 void *sel; \n\ 208 }; \n\ 209 \n\ 210 struct __lldb_imp_return_struct return_struct; \n\ 211 \n\ 212 if (debug) \n\ 213 printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ 214 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ 215 object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ 216 if (is_super) \n\ 217 { \n\ 218 if (is_super2) \n\ 219 { \n\ 220 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ 221 } \n\ 222 else \n\ 223 { \n\ 224 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ 225 } \n\ 226 } \n\ 227 else \n\ 228 { \n\ 229 // This code seems a little funny, but has its reasons... \n\ 230 // The call to [object class] is here because if this is a class, and has not been called into \n\ 231 // yet, we need to do something to force the class to initialize itself. \n\ 232 // Then the call to object_getClass will actually return the correct class, either the class \n\ 233 // if object is a class instance, or the meta-class if it is a class pointer. \n\ 234 void *class_ptr = (void *) [(id) object class]; \n\ 235 return_struct.class_addr = (id) object_getClass((id) object); \n\ 236 if (debug) \n\ 237 { \n\ 238 if (class_ptr == object) \n\ 239 { \n\ 240 printf (\"Found a class object, need to return the meta class %p -> %p\\n\", \n\ 241 class_ptr, return_struct.class_addr); \n\ 242 } \n\ 243 else \n\ 244 { \n\ 245 printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ 246 class_ptr, return_struct.class_addr); \n\ 247 } \n\ 248 } \n\ 249 } \n\ 250 \n\ 251 if (is_fixup) \n\ 252 { \n\ 253 if (is_fixed) \n\ 254 { \n\ 255 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ 256 } \n\ 257 else \n\ 258 { \n\ 259 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ 260 return_struct.sel_addr = sel_getUid (sel_name); \n\ 261 if (debug) \n\ 262 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\ 263 return_struct.sel_addr, sel_name); \n\ 264 } \n\ 265 } \n\ 266 else \n\ 267 { \n\ 268 return_struct.sel_addr = sel; \n\ 269 } \n\ 270 \n\ 271 return_struct.impl_addr = \n\ 272 class_getMethodImplementation (return_struct.class_addr, \n\ 273 return_struct.sel_addr); \n\ 274 if (debug) \n\ 275 printf (\"\\n*** Returning implementation: 0x%p.\\n\", \n\ 276 return_struct.impl_addr); \n\ 277 \n\ 278 return return_struct.impl_addr; \n\ 279} \n\ 280"; 281 282AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion( 283 AppleObjCVTables *owner, lldb::addr_t header_addr) 284 : m_valid(true), m_owner(owner), m_header_addr(header_addr), 285 m_code_start_addr(0), m_code_end_addr(0), m_next_region(0) { 286 SetUpRegion(); 287} 288 289AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() {} 290 291void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() { 292 // The header looks like: 293 // 294 // uint16_t headerSize 295 // uint16_t descSize 296 // uint32_t descCount 297 // void * next 298 // 299 // First read in the header: 300 301 char memory_buffer[16]; 302 ProcessSP process_sp = m_owner->GetProcessSP(); 303 if (!process_sp) 304 return; 305 DataExtractor data(memory_buffer, sizeof(memory_buffer), 306 process_sp->GetByteOrder(), 307 process_sp->GetAddressByteSize()); 308 size_t actual_size = 8 + process_sp->GetAddressByteSize(); 309 Status error; 310 size_t bytes_read = 311 process_sp->ReadMemory(m_header_addr, memory_buffer, actual_size, error); 312 if (bytes_read != actual_size) { 313 m_valid = false; 314 return; 315 } 316 317 lldb::offset_t offset = 0; 318 const uint16_t header_size = data.GetU16(&offset); 319 const uint16_t descriptor_size = data.GetU16(&offset); 320 const size_t num_descriptors = data.GetU32(&offset); 321 322 m_next_region = data.GetPointer(&offset); 323 324 // If the header size is 0, that means we've come in too early before this 325 // data is set up. 326 // Set ourselves as not valid, and continue. 327 if (header_size == 0 || num_descriptors == 0) { 328 m_valid = false; 329 return; 330 } 331 332 // Now read in all the descriptors: 333 // The descriptor looks like: 334 // 335 // uint32_t offset 336 // uint32_t flags 337 // 338 // Where offset is either 0 - in which case it is unused, or it is 339 // the offset of the vtable code from the beginning of the 340 // descriptor record. Below, we'll convert that into an absolute 341 // code address, since I don't want to have to compute it over and 342 // over. 343 344 // Ingest the whole descriptor array: 345 const lldb::addr_t desc_ptr = m_header_addr + header_size; 346 const size_t desc_array_size = num_descriptors * descriptor_size; 347 DataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0')); 348 uint8_t *dst = (uint8_t *)data_sp->GetBytes(); 349 350 DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(), 351 process_sp->GetAddressByteSize()); 352 bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error); 353 if (bytes_read != desc_array_size) { 354 m_valid = false; 355 return; 356 } 357 358 // The actual code for the vtables will be laid out consecutively, so I also 359 // compute the start and end of the whole code block. 360 361 offset = 0; 362 m_code_start_addr = 0; 363 m_code_end_addr = 0; 364 365 for (size_t i = 0; i < num_descriptors; i++) { 366 lldb::addr_t start_offset = offset; 367 uint32_t voffset = desc_extractor.GetU32(&offset); 368 uint32_t flags = desc_extractor.GetU32(&offset); 369 lldb::addr_t code_addr = desc_ptr + start_offset + voffset; 370 m_descriptors.push_back(VTableDescriptor(flags, code_addr)); 371 372 if (m_code_start_addr == 0 || code_addr < m_code_start_addr) 373 m_code_start_addr = code_addr; 374 if (code_addr > m_code_end_addr) 375 m_code_end_addr = code_addr; 376 377 offset = start_offset + descriptor_size; 378 } 379 // Finally, a little bird told me that all the vtable code blocks 380 // are the same size. Let's compute the blocks and if they are all 381 // the same add the size to the code end address: 382 lldb::addr_t code_size = 0; 383 bool all_the_same = true; 384 for (size_t i = 0; i < num_descriptors - 1; i++) { 385 lldb::addr_t this_size = 386 m_descriptors[i + 1].code_start - m_descriptors[i].code_start; 387 if (code_size == 0) 388 code_size = this_size; 389 else { 390 if (this_size != code_size) 391 all_the_same = false; 392 if (this_size > code_size) 393 code_size = this_size; 394 } 395 } 396 if (all_the_same) 397 m_code_end_addr += code_size; 398} 399 400bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion:: 401 AddressInRegion(lldb::addr_t addr, uint32_t &flags) { 402 if (!IsValid()) 403 return false; 404 405 if (addr < m_code_start_addr || addr > m_code_end_addr) 406 return false; 407 408 std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end(); 409 for (pos = m_descriptors.begin(); pos != end; pos++) { 410 if (addr <= (*pos).code_start) { 411 flags = (*pos).flags; 412 return true; 413 } 414 } 415 return false; 416} 417 418void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump( 419 Stream &s) { 420 s.Printf("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64 421 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n", 422 m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); 423 size_t num_elements = m_descriptors.size(); 424 for (size_t i = 0; i < num_elements; i++) { 425 s.Indent(); 426 s.Printf("Code start: 0x%" PRIx64 " Flags: %d\n", 427 m_descriptors[i].code_start, m_descriptors[i].flags); 428 } 429} 430 431AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables( 432 const ProcessSP &process_sp, const ModuleSP &objc_module_sp) 433 : m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS), 434 m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID), 435 m_objc_module_sp(objc_module_sp) { 436 if (process_sp) 437 m_process_wp = process_sp; 438} 439 440AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() { 441 ProcessSP process_sp = GetProcessSP(); 442 if (process_sp) { 443 if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) 444 process_sp->GetTarget().RemoveBreakpointByID(m_trampolines_changed_bp_id); 445 } 446} 447 448bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() { 449 if (m_trampoline_header != LLDB_INVALID_ADDRESS) 450 return true; 451 452 ProcessSP process_sp = GetProcessSP(); 453 if (process_sp) { 454 Target &target = process_sp->GetTarget(); 455 456 const ModuleList &target_modules = target.GetImages(); 457 std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex()); 458 size_t num_modules = target_modules.GetSize(); 459 if (!m_objc_module_sp) { 460 for (size_t i = 0; i < num_modules; i++) { 461 if (ObjCLanguageRuntime::Get(*process_sp) 462 ->IsModuleObjCLibrary( 463 target_modules.GetModuleAtIndexUnlocked(i))) { 464 m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i); 465 break; 466 } 467 } 468 } 469 470 if (m_objc_module_sp) { 471 ConstString trampoline_name("gdb_objc_trampolines"); 472 const Symbol *trampoline_symbol = 473 m_objc_module_sp->FindFirstSymbolWithNameAndType(trampoline_name, 474 eSymbolTypeData); 475 if (trampoline_symbol != nullptr) { 476 m_trampoline_header = trampoline_symbol->GetLoadAddress(&target); 477 if (m_trampoline_header == LLDB_INVALID_ADDRESS) 478 return false; 479 480 // Next look up the "changed" symbol and set a breakpoint on that... 481 ConstString changed_name("gdb_objc_trampolines_changed"); 482 const Symbol *changed_symbol = 483 m_objc_module_sp->FindFirstSymbolWithNameAndType(changed_name, 484 eSymbolTypeCode); 485 if (changed_symbol != nullptr) { 486 const Address changed_symbol_addr = changed_symbol->GetAddress(); 487 if (!changed_symbol_addr.IsValid()) 488 return false; 489 490 lldb::addr_t changed_addr = 491 changed_symbol_addr.GetOpcodeLoadAddress(&target); 492 if (changed_addr != LLDB_INVALID_ADDRESS) { 493 BreakpointSP trampolines_changed_bp_sp = 494 target.CreateBreakpoint(changed_addr, true, false); 495 if (trampolines_changed_bp_sp) { 496 m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); 497 trampolines_changed_bp_sp->SetCallback(RefreshTrampolines, this, 498 true); 499 trampolines_changed_bp_sp->SetBreakpointKind( 500 "objc-trampolines-changed"); 501 return true; 502 } 503 } 504 } 505 } 506 } 507 } 508 return false; 509} 510 511bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines( 512 void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id, 513 lldb::user_id_t break_loc_id) { 514 AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton; 515 if (vtable_handler->InitializeVTableSymbols()) { 516 // The Update function is called with the address of an added region. So we 517 // grab that address, and 518 // feed it into ReadRegions. Of course, our friend the ABI will get the 519 // values for us. 520 ExecutionContext exe_ctx(context->exe_ctx_ref); 521 Process *process = exe_ctx.GetProcessPtr(); 522 const ABI *abi = process->GetABI().get(); 523 524 ClangASTContext *clang_ast_context = 525 process->GetTarget().GetScratchClangASTContext(); 526 ValueList argument_values; 527 Value input_value; 528 CompilerType clang_void_ptr_type = 529 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 530 531 input_value.SetValueType(Value::eValueTypeScalar); 532 // input_value.SetContext (Value::eContextTypeClangType, 533 // clang_void_ptr_type); 534 input_value.SetCompilerType(clang_void_ptr_type); 535 argument_values.PushValue(input_value); 536 537 bool success = 538 abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values); 539 if (!success) 540 return false; 541 542 // Now get a pointer value from the zeroth argument. 543 Status error; 544 DataExtractor data; 545 error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data, 546 0, nullptr); 547 lldb::offset_t offset = 0; 548 lldb::addr_t region_addr = data.GetPointer(&offset); 549 550 if (region_addr != 0) 551 vtable_handler->ReadRegions(region_addr); 552 } 553 return false; 554} 555 556bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() { 557 // The no argument version reads the start region from the value of 558 // the gdb_regions_header, and gets started from there. 559 560 m_regions.clear(); 561 if (!InitializeVTableSymbols()) 562 return false; 563 Status error; 564 ProcessSP process_sp = GetProcessSP(); 565 if (process_sp) { 566 lldb::addr_t region_addr = 567 process_sp->ReadPointerFromMemory(m_trampoline_header, error); 568 if (error.Success()) 569 return ReadRegions(region_addr); 570 } 571 return false; 572} 573 574bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions( 575 lldb::addr_t region_addr) { 576 ProcessSP process_sp = GetProcessSP(); 577 if (!process_sp) 578 return false; 579 580 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 581 582 // We aren't starting at the trampoline symbol. 583 InitializeVTableSymbols(); 584 lldb::addr_t next_region = region_addr; 585 586 // Read in the sizes of the headers. 587 while (next_region != 0) { 588 m_regions.push_back(VTableRegion(this, next_region)); 589 if (!m_regions.back().IsValid()) { 590 m_regions.clear(); 591 return false; 592 } 593 if (log) { 594 StreamString s; 595 m_regions.back().Dump(s); 596 log->Printf("Read vtable region: \n%s", s.GetData()); 597 } 598 599 next_region = m_regions.back().GetNextRegionAddr(); 600 } 601 602 return true; 603} 604 605bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables( 606 lldb::addr_t addr, uint32_t &flags) { 607 region_collection::iterator pos, end = m_regions.end(); 608 for (pos = m_regions.begin(); pos != end; pos++) { 609 if ((*pos).AddressInRegion(addr, flags)) 610 return true; 611 } 612 return false; 613} 614 615const AppleObjCTrampolineHandler::DispatchFunction 616 AppleObjCTrampolineHandler::g_dispatch_functions[] = { 617 // NAME STRET SUPER SUPER2 FIXUP TYPE 618 {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone}, 619 {"objc_msgSend_fixup", false, false, false, 620 DispatchFunction::eFixUpToFix}, 621 {"objc_msgSend_fixedup", false, false, false, 622 DispatchFunction::eFixUpFixed}, 623 {"objc_msgSend_stret", true, false, false, 624 DispatchFunction::eFixUpNone}, 625 {"objc_msgSend_stret_fixup", true, false, false, 626 DispatchFunction::eFixUpToFix}, 627 {"objc_msgSend_stret_fixedup", true, false, false, 628 DispatchFunction::eFixUpFixed}, 629 {"objc_msgSend_fpret", false, false, false, 630 DispatchFunction::eFixUpNone}, 631 {"objc_msgSend_fpret_fixup", false, false, false, 632 DispatchFunction::eFixUpToFix}, 633 {"objc_msgSend_fpret_fixedup", false, false, false, 634 DispatchFunction::eFixUpFixed}, 635 {"objc_msgSend_fp2ret", false, false, true, 636 DispatchFunction::eFixUpNone}, 637 {"objc_msgSend_fp2ret_fixup", false, false, true, 638 DispatchFunction::eFixUpToFix}, 639 {"objc_msgSend_fp2ret_fixedup", false, false, true, 640 DispatchFunction::eFixUpFixed}, 641 {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone}, 642 {"objc_msgSendSuper_stret", true, true, false, 643 DispatchFunction::eFixUpNone}, 644 {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone}, 645 {"objc_msgSendSuper2_fixup", false, true, true, 646 DispatchFunction::eFixUpToFix}, 647 {"objc_msgSendSuper2_fixedup", false, true, true, 648 DispatchFunction::eFixUpFixed}, 649 {"objc_msgSendSuper2_stret", true, true, true, 650 DispatchFunction::eFixUpNone}, 651 {"objc_msgSendSuper2_stret_fixup", true, true, true, 652 DispatchFunction::eFixUpToFix}, 653 {"objc_msgSendSuper2_stret_fixedup", true, true, true, 654 DispatchFunction::eFixUpFixed}, 655}; 656 657AppleObjCTrampolineHandler::AppleObjCTrampolineHandler( 658 const ProcessSP &process_sp, const ModuleSP &objc_module_sp) 659 : m_process_wp(), m_objc_module_sp(objc_module_sp), 660 m_lookup_implementation_function_code(nullptr), 661 m_impl_fn_addr(LLDB_INVALID_ADDRESS), 662 m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS), 663 m_msg_forward_addr(LLDB_INVALID_ADDRESS) { 664 if (process_sp) 665 m_process_wp = process_sp; 666 // Look up the known resolution functions: 667 668 ConstString get_impl_name("class_getMethodImplementation"); 669 ConstString get_impl_stret_name("class_getMethodImplementation_stret"); 670 ConstString msg_forward_name("_objc_msgForward"); 671 ConstString msg_forward_stret_name("_objc_msgForward_stret"); 672 673 Target *target = process_sp ? &process_sp->GetTarget() : nullptr; 674 const Symbol *class_getMethodImplementation = 675 m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_name, 676 eSymbolTypeCode); 677 const Symbol *class_getMethodImplementation_stret = 678 m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_stret_name, 679 eSymbolTypeCode); 680 const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType( 681 msg_forward_name, eSymbolTypeCode); 682 const Symbol *msg_forward_stret = 683 m_objc_module_sp->FindFirstSymbolWithNameAndType(msg_forward_stret_name, 684 eSymbolTypeCode); 685 686 if (class_getMethodImplementation) 687 m_impl_fn_addr = 688 class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress( 689 target); 690 if (class_getMethodImplementation_stret) 691 m_impl_stret_fn_addr = 692 class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress( 693 target); 694 if (msg_forward) 695 m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target); 696 if (msg_forward_stret) 697 m_msg_forward_stret_addr = 698 msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target); 699 700 // FIXME: Do some kind of logging here. 701 if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) { 702 // If we can't even find the ordinary get method implementation function, 703 // then we aren't going to be able to 704 // step through any method dispatches. Warn to that effect and get out of 705 // here. 706 if (process_sp->CanJIT()) { 707 process_sp->GetTarget().GetDebugger().GetErrorFile()->Printf( 708 "Could not find implementation lookup function \"%s\"" 709 " step in through ObjC method dispatch will not work.\n", 710 get_impl_name.AsCString()); 711 } 712 return; 713 } else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) { 714 // It there is no stret return lookup function, assume that it is the same 715 // as the straight lookup: 716 m_impl_stret_fn_addr = m_impl_fn_addr; 717 // Also we will use the version of the lookup code that doesn't rely on the 718 // stret version of the function. 719 m_lookup_implementation_function_code = 720 g_lookup_implementation_no_stret_function_code; 721 } else { 722 m_lookup_implementation_function_code = 723 g_lookup_implementation_with_stret_function_code; 724 } 725 726 // Look up the addresses for the objc dispatch functions and cache 727 // them. For now I'm inspecting the symbol names dynamically to 728 // figure out how to dispatch to them. If it becomes more 729 // complicated than this we can turn the g_dispatch_functions char * 730 // array into a template table, and populate the DispatchFunction 731 // map from there. 732 733 for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) { 734 ConstString name_const_str(g_dispatch_functions[i].name); 735 const Symbol *msgSend_symbol = 736 m_objc_module_sp->FindFirstSymbolWithNameAndType(name_const_str, 737 eSymbolTypeCode); 738 if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) { 739 // FIXME: Make g_dispatch_functions static table of 740 // DispatchFunctions, and have the map be address->index. 741 // Problem is we also need to lookup the dispatch function. For 742 // now we could have a side table of stret & non-stret dispatch 743 // functions. If that's as complex as it gets, we're fine. 744 745 lldb::addr_t sym_addr = 746 msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target); 747 748 m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i)); 749 } 750 } 751 752 // Build our vtable dispatch handler here: 753 m_vtables_up.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); 754 if (m_vtables_up) 755 m_vtables_up->ReadRegions(); 756} 757 758lldb::addr_t 759AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread, 760 ValueList &dispatch_values) { 761 ThreadSP thread_sp(thread.shared_from_this()); 762 ExecutionContext exe_ctx(thread_sp); 763 DiagnosticManager diagnostics; 764 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 765 766 lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; 767 FunctionCaller *impl_function_caller = nullptr; 768 769 // Scope for mutex locker: 770 { 771 std::lock_guard<std::mutex> guard(m_impl_function_mutex); 772 773 // First stage is to make the ClangUtility to hold our injected function: 774 775 if (!m_impl_code) { 776 if (m_lookup_implementation_function_code != nullptr) { 777 Status error; 778 m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage( 779 m_lookup_implementation_function_code, eLanguageTypeObjC, 780 g_lookup_implementation_function_name, error)); 781 if (error.Fail()) { 782 if (log) 783 log->Printf( 784 "Failed to get Utility Function for implementation lookup: %s.", 785 error.AsCString()); 786 m_impl_code.reset(); 787 return args_addr; 788 } 789 790 if (!m_impl_code->Install(diagnostics, exe_ctx)) { 791 if (log) { 792 log->Printf("Failed to install implementation lookup."); 793 diagnostics.Dump(log); 794 } 795 m_impl_code.reset(); 796 return args_addr; 797 } 798 } else { 799 if (log) 800 log->Printf("No method lookup implementation code."); 801 return LLDB_INVALID_ADDRESS; 802 } 803 804 // Next make the runner function for our implementation utility function. 805 ClangASTContext *clang_ast_context = 806 thread.GetProcess()->GetTarget().GetScratchClangASTContext(); 807 CompilerType clang_void_ptr_type = 808 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 809 Status error; 810 811 impl_function_caller = m_impl_code->MakeFunctionCaller( 812 clang_void_ptr_type, dispatch_values, thread_sp, error); 813 if (error.Fail()) { 814 if (log) 815 log->Printf( 816 "Error getting function caller for dispatch lookup: \"%s\".", 817 error.AsCString()); 818 return args_addr; 819 } 820 } else { 821 impl_function_caller = m_impl_code->GetFunctionCaller(); 822 } 823 } 824 825 diagnostics.Clear(); 826 827 // Now write down the argument values for this particular call. 828 // This looks like it might be a race condition if other threads 829 // were calling into here, but actually it isn't because we allocate 830 // a new args structure for this call by passing args_addr = 831 // LLDB_INVALID_ADDRESS... 832 833 if (!impl_function_caller->WriteFunctionArguments( 834 exe_ctx, args_addr, dispatch_values, diagnostics)) { 835 if (log) { 836 log->Printf("Error writing function arguments."); 837 diagnostics.Dump(log); 838 } 839 return args_addr; 840 } 841 842 return args_addr; 843} 844 845ThreadPlanSP 846AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread, 847 bool stop_others) { 848 ThreadPlanSP ret_plan_sp; 849 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); 850 851 DispatchFunction this_dispatch; 852 bool found_it = false; 853 854 // First step is to look and see if we are in one of the known ObjC 855 // dispatch functions. We've already compiled a table of same, so 856 // consult it. 857 858 MsgsendMap::iterator pos; 859 pos = m_msgSend_map.find(curr_pc); 860 if (pos != m_msgSend_map.end()) { 861 this_dispatch = g_dispatch_functions[(*pos).second]; 862 found_it = true; 863 } 864 865 // Next check to see if we are in a vtable region: 866 867 if (!found_it) { 868 uint32_t flags; 869 if (m_vtables_up) { 870 found_it = m_vtables_up->IsAddressInVTables(curr_pc, flags); 871 if (found_it) { 872 this_dispatch.name = "vtable"; 873 this_dispatch.stret_return = 874 (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == 875 AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; 876 this_dispatch.is_super = false; 877 this_dispatch.is_super2 = false; 878 this_dispatch.fixedup = DispatchFunction::eFixUpFixed; 879 } 880 } 881 } 882 883 if (found_it) { 884 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP)); 885 886 // We are decoding a method dispatch. First job is to pull the 887 // arguments out: 888 889 lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); 890 891 const ABI *abi = nullptr; 892 ProcessSP process_sp(thread.CalculateProcess()); 893 if (process_sp) 894 abi = process_sp->GetABI().get(); 895 if (abi == nullptr) 896 return ret_plan_sp; 897 898 TargetSP target_sp(thread.CalculateTarget()); 899 900 ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext(); 901 ValueList argument_values; 902 Value void_ptr_value; 903 CompilerType clang_void_ptr_type = 904 clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); 905 void_ptr_value.SetValueType(Value::eValueTypeScalar); 906 // void_ptr_value.SetContext (Value::eContextTypeClangType, 907 // clang_void_ptr_type); 908 void_ptr_value.SetCompilerType(clang_void_ptr_type); 909 910 int obj_index; 911 int sel_index; 912 913 // If this is a struct return dispatch, then the first argument is 914 // the return struct pointer, and the object is the second, and 915 // the selector is the third. Otherwise the object is the first 916 // and the selector the second. 917 if (this_dispatch.stret_return) { 918 obj_index = 1; 919 sel_index = 2; 920 argument_values.PushValue(void_ptr_value); 921 argument_values.PushValue(void_ptr_value); 922 argument_values.PushValue(void_ptr_value); 923 } else { 924 obj_index = 0; 925 sel_index = 1; 926 argument_values.PushValue(void_ptr_value); 927 argument_values.PushValue(void_ptr_value); 928 } 929 930 bool success = abi->GetArgumentValues(thread, argument_values); 931 if (!success) 932 return ret_plan_sp; 933 934 lldb::addr_t obj_addr = 935 argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong(); 936 if (obj_addr == 0x0) { 937 if (log) 938 log->Printf( 939 "Asked to step to dispatch to nil object, returning empty plan."); 940 return ret_plan_sp; 941 } 942 943 ExecutionContext exe_ctx(thread.shared_from_this()); 944 Process *process = exe_ctx.GetProcessPtr(); 945 // isa_addr will store the class pointer that the method is being 946 // dispatched to - so either the class directly or the super class 947 // if this is one of the objc_msgSendSuper flavors. That's mostly 948 // used to look up the class/selector pair in our cache. 949 950 lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; 951 lldb::addr_t sel_addr = 952 argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); 953 954 // Figure out the class this is being dispatched to and see if 955 // we've already cached this method call, If so we can push a 956 // run-to-address plan directly. Otherwise we have to figure out 957 // where the implementation lives. 958 959 if (this_dispatch.is_super) { 960 if (this_dispatch.is_super2) { 961 // In the objc_msgSendSuper2 case, we don't get the object 962 // directly, we get a structure containing the object and the 963 // class to which the super message is being sent. So we need 964 // to dig the super out of the class and use that. 965 966 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 967 super_value.GetScalar() += process->GetAddressByteSize(); 968 super_value.ResolveValue(&exe_ctx); 969 970 if (super_value.GetScalar().IsValid()) { 971 972 // isa_value now holds the class pointer. The second word of the 973 // class pointer is the super-class pointer: 974 super_value.GetScalar() += process->GetAddressByteSize(); 975 super_value.ResolveValue(&exe_ctx); 976 if (super_value.GetScalar().IsValid()) 977 isa_addr = super_value.GetScalar().ULongLong(); 978 else { 979 if (log) 980 log->Printf("Failed to extract the super class value from the " 981 "class in objc_super."); 982 } 983 } else { 984 if (log) 985 log->Printf("Failed to extract the class value from objc_super."); 986 } 987 } else { 988 // In the objc_msgSendSuper case, we don't get the object 989 // directly, we get a two element structure containing the 990 // object and the super class to which the super message is 991 // being sent. So the class we want is the second element of 992 // this structure. 993 994 Value super_value(*(argument_values.GetValueAtIndex(obj_index))); 995 super_value.GetScalar() += process->GetAddressByteSize(); 996 super_value.ResolveValue(&exe_ctx); 997 998 if (super_value.GetScalar().IsValid()) { 999 isa_addr = super_value.GetScalar().ULongLong(); 1000 } else { 1001 if (log) 1002 log->Printf("Failed to extract the class value from objc_super."); 1003 } 1004 } 1005 } else { 1006 // In the direct dispatch case, the object->isa is the class pointer we 1007 // want. 1008 1009 // This is a little cheesy, but since object->isa is the first field, 1010 // making the object value a load address value and resolving it will get 1011 // the pointer sized data pointed to by that value... 1012 1013 // Note, it isn't a fatal error not to be able to get the 1014 // address from the object, since this might be a "tagged 1015 // pointer" which isn't a real object, but rather some word 1016 // length encoded dingus. 1017 1018 Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); 1019 1020 isa_value.SetValueType(Value::eValueTypeLoadAddress); 1021 isa_value.ResolveValue(&exe_ctx); 1022 if (isa_value.GetScalar().IsValid()) { 1023 isa_addr = isa_value.GetScalar().ULongLong(); 1024 } else { 1025 if (log) 1026 log->Printf("Failed to extract the isa value from object."); 1027 } 1028 } 1029 1030 // Okay, we've got the address of the class for which we're resolving this, 1031 // let's see if it's in our cache: 1032 lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; 1033 1034 if (isa_addr != LLDB_INVALID_ADDRESS) { 1035 if (log) { 1036 log->Printf("Resolving call for class - 0x%" PRIx64 1037 " and selector - 0x%" PRIx64, 1038 isa_addr, sel_addr); 1039 } 1040 ObjCLanguageRuntime *objc_runtime = 1041 ObjCLanguageRuntime::Get(*thread.GetProcess()); 1042 assert(objc_runtime != nullptr); 1043 1044 impl_addr = objc_runtime->LookupInMethodCache(isa_addr, sel_addr); 1045 } 1046 1047 if (impl_addr != LLDB_INVALID_ADDRESS) { 1048 // Yup, it was in the cache, so we can run to that address directly. 1049 1050 if (log) 1051 log->Printf("Found implementation address in cache: 0x%" PRIx64, 1052 impl_addr); 1053 1054 ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(thread, impl_addr, 1055 stop_others); 1056 } else { 1057 // We haven't seen this class/selector pair yet. Look it up. 1058 StreamString errors; 1059 Address impl_code_address; 1060 1061 ValueList dispatch_values; 1062 1063 // We've will inject a little function in the target that takes the 1064 // object, selector and some flags, 1065 // and figures out the implementation. Looks like: 1066 // void *__lldb_objc_find_implementation_for_selector (void *object, 1067 // void *sel, 1068 // int is_stret, 1069 // int is_super, 1070 // int is_super2, 1071 // int is_fixup, 1072 // int is_fixed, 1073 // int debug) 1074 // So set up the arguments for that call. 1075 1076 dispatch_values.PushValue(*(argument_values.GetValueAtIndex(obj_index))); 1077 dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index))); 1078 1079 Value flag_value; 1080 CompilerType clang_int_type = 1081 clang_ast_context->GetBuiltinTypeForEncodingAndBitSize( 1082 lldb::eEncodingSint, 32); 1083 flag_value.SetValueType(Value::eValueTypeScalar); 1084 // flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); 1085 flag_value.SetCompilerType(clang_int_type); 1086 1087 if (this_dispatch.stret_return) 1088 flag_value.GetScalar() = 1; 1089 else 1090 flag_value.GetScalar() = 0; 1091 dispatch_values.PushValue(flag_value); 1092 1093 if (this_dispatch.is_super) 1094 flag_value.GetScalar() = 1; 1095 else 1096 flag_value.GetScalar() = 0; 1097 dispatch_values.PushValue(flag_value); 1098 1099 if (this_dispatch.is_super2) 1100 flag_value.GetScalar() = 1; 1101 else 1102 flag_value.GetScalar() = 0; 1103 dispatch_values.PushValue(flag_value); 1104 1105 switch (this_dispatch.fixedup) { 1106 case DispatchFunction::eFixUpNone: 1107 flag_value.GetScalar() = 0; 1108 dispatch_values.PushValue(flag_value); 1109 dispatch_values.PushValue(flag_value); 1110 break; 1111 case DispatchFunction::eFixUpFixed: 1112 flag_value.GetScalar() = 1; 1113 dispatch_values.PushValue(flag_value); 1114 flag_value.GetScalar() = 1; 1115 dispatch_values.PushValue(flag_value); 1116 break; 1117 case DispatchFunction::eFixUpToFix: 1118 flag_value.GetScalar() = 1; 1119 dispatch_values.PushValue(flag_value); 1120 flag_value.GetScalar() = 0; 1121 dispatch_values.PushValue(flag_value); 1122 break; 1123 } 1124 if (log && log->GetVerbose()) 1125 flag_value.GetScalar() = 1; 1126 else 1127 flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. 1128 dispatch_values.PushValue(flag_value); 1129 1130 // The step through code might have to fill in the cache, so it 1131 // is not safe to run only one thread. So we override the 1132 // stop_others value passed in to us here: 1133 const bool trampoline_stop_others = false; 1134 ret_plan_sp = std::make_shared<AppleThreadPlanStepThroughObjCTrampoline>( 1135 thread, this, dispatch_values, isa_addr, sel_addr, 1136 trampoline_stop_others); 1137 if (log) { 1138 StreamString s; 1139 ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); 1140 log->Printf("Using ObjC step plan: %s.\n", s.GetData()); 1141 } 1142 } 1143 } 1144 1145 return ret_plan_sp; 1146} 1147 1148FunctionCaller * 1149AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() { 1150 return m_impl_code->GetFunctionCaller(); 1151} 1152