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Diffstat (limited to 'source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp')
| -rw-r--r-- | source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp | 1144 |
1 files changed, 1144 insertions, 0 deletions
diff --git a/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp b/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp new file mode 100644 index 0000000000000..d38a076ad5d74 --- /dev/null +++ b/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp @@ -0,0 +1,1144 @@ +//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "AppleObjCTrampolineHandler.h" + +// C Includes +// C++ Includes +// Other libraries and framework includes +// Project includes +#include "AppleThreadPlanStepThroughObjCTrampoline.h" + +#include "lldb/Breakpoint/StoppointCallbackContext.h" +#include "lldb/Core/ConstString.h" +#include "lldb/Core/Debugger.h" +#include "lldb/Core/Log.h" +#include "lldb/Core/Module.h" +#include "lldb/Core/StreamFile.h" +#include "lldb/Core/Value.h" +#include "lldb/Expression/UserExpression.h" +#include "lldb/Expression/FunctionCaller.h" +#include "lldb/Expression/UtilityFunction.h" +#include "lldb/Host/FileSpec.h" +#include "lldb/Symbol/ClangASTContext.h" +#include "lldb/Symbol/Symbol.h" +#include "lldb/Target/ABI.h" +#include "lldb/Target/ObjCLanguageRuntime.h" +#include "lldb/Target/Process.h" +#include "lldb/Target/RegisterContext.h" +#include "lldb/Target/Target.h" +#include "lldb/Target/Thread.h" +#include "lldb/Target/ExecutionContext.h" +#include "lldb/Target/ThreadPlanRunToAddress.h" + +#include "llvm/ADT/STLExtras.h" + +using namespace lldb; +using namespace lldb_private; + +const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name = "__lldb_objc_find_implementation_for_selector"; +const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_code = NULL; +const char *AppleObjCTrampolineHandler::g_lookup_implementation_with_stret_function_code = " \n\ +extern \"C\" \n\ +{ \n\ + extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ + extern void *class_getMethodImplementation_stret(void *objc_class, void *sel); \n\ + extern void * object_getClass (id object); \n\ + extern void * sel_getUid(char *name); \n\ + extern int printf(const char *format, ...); \n\ +} \n\ +extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ + void *sel, \n\ + int is_stret, \n\ + int is_super, \n\ + int is_super2, \n\ + int is_fixup, \n\ + int is_fixed, \n\ + int debug) \n\ +{ \n\ + struct __lldb_imp_return_struct \n\ + { \n\ + void *class_addr; \n\ + void *sel_addr; \n\ + void *impl_addr; \n\ + }; \n\ + \n\ + struct __lldb_objc_class { \n\ + void *isa; \n\ + void *super_ptr; \n\ + }; \n\ + struct __lldb_objc_super { \n\ + void *reciever; \n\ + struct __lldb_objc_class *class_ptr; \n\ + }; \n\ + struct __lldb_msg_ref { \n\ + void *dont_know; \n\ + void *sel; \n\ + }; \n\ + \n\ + struct __lldb_imp_return_struct return_struct; \n\ + \n\ + if (debug) \n\ + printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ + \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ + object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ + if (is_super) \n\ + { \n\ + if (is_super2) \n\ + { \n\ + return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ + } \n\ + else \n\ + { \n\ + return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ + } \n\ + } \n\ + else \n\ + { \n\ + // This code seems a little funny, but has its reasons... \n\ + // The call to [object class] is here because if this is a class, and has not been called into \n\ + // yet, we need to do something to force the class to initialize itself. \n\ + // Then the call to object_getClass will actually return the correct class, either the class \n\ + // if object is a class instance, or the meta-class if it is a class pointer. \n\ + void *class_ptr = (void *) [(id) object class]; \n\ + return_struct.class_addr = (id) object_getClass((id) object); \n\ + if (debug) \n\ + { \n\ + if (class_ptr == object) \n\ + { \n\ + printf (\"Found a class object, need to use the meta class %p -> %p\\n\", \n\ + class_ptr, return_struct.class_addr); \n\ + } \n\ + else \n\ + { \n\ + printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ + class_ptr, return_struct.class_addr); \n\ + } \n\ + } \n\ + } \n\ + \n\ + if (is_fixup) \n\ + { \n\ + if (is_fixed) \n\ + { \n\ + return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ + } \n\ + else \n\ + { \n\ + char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ + return_struct.sel_addr = sel_getUid (sel_name); \n\ + if (debug) \n\ + printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\", \n\ + return_struct.sel_addr, sel_name); \n\ + } \n\ + } \n\ + else \n\ + { \n\ + return_struct.sel_addr = sel; \n\ + } \n\ + \n\ + if (is_stret) \n\ + { \n\ + return_struct.impl_addr = class_getMethodImplementation_stret (return_struct.class_addr, \n\ + return_struct.sel_addr); \n\ + } \n\ + else \n\ + { \n\ + return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ + return_struct.sel_addr); \n\ + } \n\ + if (debug) \n\ + printf (\"\\n*** Returning implementation: %p.\\n\", return_struct.impl_addr); \n\ + \n\ + return return_struct.impl_addr; \n\ +} \n\ +"; +const char *AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code = " \n\ +extern \"C\" \n\ +{ \n\ + extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\ + extern void * object_getClass (id object); \n\ + extern void * sel_getUid(char *name); \n\ + extern int printf(const char *format, ...); \n\ +} \n\ +extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\ + void *sel, \n\ + int is_stret, \n\ + int is_super, \n\ + int is_super2, \n\ + int is_fixup, \n\ + int is_fixed, \n\ + int debug) \n\ +{ \n\ + struct __lldb_imp_return_struct \n\ + { \n\ + void *class_addr; \n\ + void *sel_addr; \n\ + void *impl_addr; \n\ + }; \n\ + \n\ + struct __lldb_objc_class { \n\ + void *isa; \n\ + void *super_ptr; \n\ + }; \n\ + struct __lldb_objc_super { \n\ + void *reciever; \n\ + struct __lldb_objc_class *class_ptr; \n\ + }; \n\ + struct __lldb_msg_ref { \n\ + void *dont_know; \n\ + void *sel; \n\ + }; \n\ + \n\ + struct __lldb_imp_return_struct return_struct; \n\ + \n\ + if (debug) \n\ + printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\ + \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\ + object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\ + if (is_super) \n\ + { \n\ + if (is_super2) \n\ + { \n\ + return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\ + } \n\ + else \n\ + { \n\ + return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\ + } \n\ + } \n\ + else \n\ + { \n\ + // This code seems a little funny, but has its reasons... \n\ + // The call to [object class] is here because if this is a class, and has not been called into \n\ + // yet, we need to do something to force the class to initialize itself. \n\ + // Then the call to object_getClass will actually return the correct class, either the class \n\ + // if object is a class instance, or the meta-class if it is a class pointer. \n\ + void *class_ptr = (void *) [(id) object class]; \n\ + return_struct.class_addr = (id) object_getClass((id) object); \n\ + if (debug) \n\ + { \n\ + if (class_ptr == object) \n\ + { \n\ + printf (\"Found a class object, need to return the meta class %p -> %p\\n\", \n\ + class_ptr, return_struct.class_addr); \n\ + } \n\ + else \n\ + { \n\ + printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\ + class_ptr, return_struct.class_addr); \n\ + } \n\ + } \n\ + } \n\ + \n\ + if (is_fixup) \n\ + { \n\ + if (is_fixed) \n\ + { \n\ + return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\ + } \n\ + else \n\ + { \n\ + char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\ + return_struct.sel_addr = sel_getUid (sel_name); \n\ + if (debug) \n\ + printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\", \n\ + return_struct.sel_addr, sel_name); \n\ + } \n\ + } \n\ + else \n\ + { \n\ + return_struct.sel_addr = sel; \n\ + } \n\ + \n\ + return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\ + return_struct.sel_addr); \n\ + if (debug) \n\ + printf (\"\\n*** Returning implementation: 0x%p.\\n\", return_struct.impl_addr); \n\ + \n\ + return return_struct.impl_addr; \n\ +} \n\ +"; + +AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion(AppleObjCVTables *owner, lldb::addr_t header_addr) : + m_valid (true), + m_owner(owner), + m_header_addr (header_addr), + m_code_start_addr(0), + m_code_end_addr (0), + m_next_region (0) +{ + SetUpRegion (); +} + +AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() +{ +} + +void +AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() +{ + // The header looks like: + // + // uint16_t headerSize + // uint16_t descSize + // uint32_t descCount + // void * next + // + // First read in the header: + + char memory_buffer[16]; + ProcessSP process_sp = m_owner->GetProcessSP(); + if (!process_sp) + return; + DataExtractor data(memory_buffer, sizeof(memory_buffer), + process_sp->GetByteOrder(), + process_sp->GetAddressByteSize()); + size_t actual_size = 8 + process_sp->GetAddressByteSize(); + Error error; + size_t bytes_read = process_sp->ReadMemory (m_header_addr, memory_buffer, actual_size, error); + if (bytes_read != actual_size) + { + m_valid = false; + return; + } + + lldb::offset_t offset = 0; + const uint16_t header_size = data.GetU16(&offset); + const uint16_t descriptor_size = data.GetU16(&offset); + const size_t num_descriptors = data.GetU32(&offset); + + m_next_region = data.GetPointer(&offset); + + // If the header size is 0, that means we've come in too early before this data is set up. + // Set ourselves as not valid, and continue. + if (header_size == 0 || num_descriptors == 0) + { + m_valid = false; + return; + } + + // Now read in all the descriptors: + // The descriptor looks like: + // + // uint32_t offset + // uint32_t flags + // + // Where offset is either 0 - in which case it is unused, or + // it is the offset of the vtable code from the beginning of the descriptor record. + // Below, we'll convert that into an absolute code address, since I don't want to have + // to compute it over and over. + + // Ingest the whole descriptor array: + const lldb::addr_t desc_ptr = m_header_addr + header_size; + const size_t desc_array_size = num_descriptors * descriptor_size; + DataBufferSP data_sp(new DataBufferHeap (desc_array_size, '\0')); + uint8_t* dst = (uint8_t*)data_sp->GetBytes(); + + DataExtractor desc_extractor (dst, desc_array_size, + process_sp->GetByteOrder(), + process_sp->GetAddressByteSize()); + bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error); + if (bytes_read != desc_array_size) + { + m_valid = false; + return; + } + + // The actual code for the vtables will be laid out consecutively, so I also + // compute the start and end of the whole code block. + + offset = 0; + m_code_start_addr = 0; + m_code_end_addr = 0; + + for (size_t i = 0; i < num_descriptors; i++) + { + lldb::addr_t start_offset = offset; + uint32_t voffset = desc_extractor.GetU32 (&offset); + uint32_t flags = desc_extractor.GetU32 (&offset); + lldb::addr_t code_addr = desc_ptr + start_offset + voffset; + m_descriptors.push_back (VTableDescriptor(flags, code_addr)); + + if (m_code_start_addr == 0 || code_addr < m_code_start_addr) + m_code_start_addr = code_addr; + if (code_addr > m_code_end_addr) + m_code_end_addr = code_addr; + + offset = start_offset + descriptor_size; + } + // Finally, a little bird told me that all the vtable code blocks are the same size. + // Let's compute the blocks and if they are all the same add the size to the code end address: + lldb::addr_t code_size = 0; + bool all_the_same = true; + for (size_t i = 0; i < num_descriptors - 1; i++) + { + lldb::addr_t this_size = m_descriptors[i + 1].code_start - m_descriptors[i].code_start; + if (code_size == 0) + code_size = this_size; + else + { + if (this_size != code_size) + all_the_same = false; + if (this_size > code_size) + code_size = this_size; + } + } + if (all_the_same) + m_code_end_addr += code_size; +} + +bool +AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::AddressInRegion (lldb::addr_t addr, uint32_t &flags) +{ + if (!IsValid()) + return false; + + if (addr < m_code_start_addr || addr > m_code_end_addr) + return false; + + std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end(); + for (pos = m_descriptors.begin(); pos != end; pos++) + { + if (addr <= (*pos).code_start) + { + flags = (*pos).flags; + return true; + } + } + return false; +} + +void +AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump (Stream &s) +{ + s.Printf ("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n", + m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region); + size_t num_elements = m_descriptors.size(); + for (size_t i = 0; i < num_elements; i++) + { + s.Indent(); + s.Printf ("Code start: 0x%" PRIx64 " Flags: %d\n", m_descriptors[i].code_start, m_descriptors[i].flags); + } +} + +AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables (const ProcessSP &process_sp, + const ModuleSP &objc_module_sp) : + m_process_wp (), + m_trampoline_header (LLDB_INVALID_ADDRESS), + m_trampolines_changed_bp_id (LLDB_INVALID_BREAK_ID), + m_objc_module_sp (objc_module_sp) +{ + if (process_sp) + m_process_wp = process_sp; +} + +AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() +{ + ProcessSP process_sp = GetProcessSP (); + if (process_sp) + { + if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID) + process_sp->GetTarget().RemoveBreakpointByID (m_trampolines_changed_bp_id); + } +} + +bool +AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols () +{ + if (m_trampoline_header != LLDB_INVALID_ADDRESS) + return true; + + ProcessSP process_sp = GetProcessSP (); + if (process_sp) + { + Target &target = process_sp->GetTarget(); + + const ModuleList &target_modules = target.GetImages(); + Mutex::Locker modules_locker(target_modules.GetMutex()); + size_t num_modules = target_modules.GetSize(); + if (!m_objc_module_sp) + { + for (size_t i = 0; i < num_modules; i++) + { + if (process_sp->GetObjCLanguageRuntime()->IsModuleObjCLibrary (target_modules.GetModuleAtIndexUnlocked(i))) + { + m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i); + break; + } + } + } + + if (m_objc_module_sp) + { + ConstString trampoline_name ("gdb_objc_trampolines"); + const Symbol *trampoline_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (trampoline_name, + eSymbolTypeData); + if (trampoline_symbol != NULL) + { + m_trampoline_header = trampoline_symbol->GetLoadAddress(&target); + if (m_trampoline_header == LLDB_INVALID_ADDRESS) + return false; + + // Next look up the "changed" symbol and set a breakpoint on that... + ConstString changed_name ("gdb_objc_trampolines_changed"); + const Symbol *changed_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (changed_name, + eSymbolTypeCode); + if (changed_symbol != NULL) + { + const Address changed_symbol_addr = changed_symbol->GetAddress(); + if (!changed_symbol_addr.IsValid()) + return false; + + lldb::addr_t changed_addr = changed_symbol_addr.GetOpcodeLoadAddress (&target); + if (changed_addr != LLDB_INVALID_ADDRESS) + { + BreakpointSP trampolines_changed_bp_sp = target.CreateBreakpoint (changed_addr, true, false); + if (trampolines_changed_bp_sp) + { + m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID(); + trampolines_changed_bp_sp->SetCallback (RefreshTrampolines, this, true); + trampolines_changed_bp_sp->SetBreakpointKind ("objc-trampolines-changed"); + return true; + } + } + } + } + } + } + return false; +} + +bool +AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines (void *baton, + StoppointCallbackContext *context, + lldb::user_id_t break_id, + lldb::user_id_t break_loc_id) +{ + AppleObjCVTables *vtable_handler = (AppleObjCVTables *) baton; + if (vtable_handler->InitializeVTableSymbols()) + { + // The Update function is called with the address of an added region. So we grab that address, and + // feed it into ReadRegions. Of course, our friend the ABI will get the values for us. + ExecutionContext exe_ctx (context->exe_ctx_ref); + Process *process = exe_ctx.GetProcessPtr(); + const ABI *abi = process->GetABI().get(); + + ClangASTContext *clang_ast_context = process->GetTarget().GetScratchClangASTContext(); + ValueList argument_values; + Value input_value; + CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); + + input_value.SetValueType (Value::eValueTypeScalar); + //input_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type); + input_value.SetCompilerType (clang_void_ptr_type); + argument_values.PushValue(input_value); + + bool success = abi->GetArgumentValues (exe_ctx.GetThreadRef(), argument_values); + if (!success) + return false; + + // Now get a pointer value from the zeroth argument. + Error error; + DataExtractor data; + error = argument_values.GetValueAtIndex(0)->GetValueAsData (&exe_ctx, + data, + 0, + NULL); + lldb::offset_t offset = 0; + lldb::addr_t region_addr = data.GetPointer(&offset); + + if (region_addr != 0) + vtable_handler->ReadRegions(region_addr); + } + return false; +} + +bool +AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions () +{ + // The no argument version reads the start region from the value of the gdb_regions_header, and + // gets started from there. + + m_regions.clear(); + if (!InitializeVTableSymbols()) + return false; + Error error; + ProcessSP process_sp = GetProcessSP (); + if (process_sp) + { + lldb::addr_t region_addr = process_sp->ReadPointerFromMemory (m_trampoline_header, error); + if (error.Success()) + return ReadRegions (region_addr); + } + return false; +} + +bool +AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions (lldb::addr_t region_addr) +{ + ProcessSP process_sp = GetProcessSP (); + if (!process_sp) + return false; + + Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); + + // We aren't starting at the trampoline symbol. + InitializeVTableSymbols (); + lldb::addr_t next_region = region_addr; + + // Read in the sizes of the headers. + while (next_region != 0) + { + m_regions.push_back (VTableRegion(this, next_region)); + if (!m_regions.back().IsValid()) + { + m_regions.clear(); + return false; + } + if (log) + { + StreamString s; + m_regions.back().Dump(s); + log->Printf("Read vtable region: \n%s", s.GetData()); + } + + next_region = m_regions.back().GetNextRegionAddr(); + } + + return true; +} + +bool +AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables (lldb::addr_t addr, uint32_t &flags) +{ + region_collection::iterator pos, end = m_regions.end(); + for (pos = m_regions.begin(); pos != end; pos++) + { + if ((*pos).AddressInRegion (addr, flags)) + return true; + } + return false; +} + +const AppleObjCTrampolineHandler::DispatchFunction +AppleObjCTrampolineHandler::g_dispatch_functions[] = +{ + // NAME STRET SUPER SUPER2 FIXUP TYPE + {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone }, + {"objc_msgSend_fixup", false, false, false, DispatchFunction::eFixUpToFix }, + {"objc_msgSend_fixedup", false, false, false, DispatchFunction::eFixUpFixed }, + {"objc_msgSend_stret", true, false, false, DispatchFunction::eFixUpNone }, + {"objc_msgSend_stret_fixup", true, false, false, DispatchFunction::eFixUpToFix }, + {"objc_msgSend_stret_fixedup", true, false, false, DispatchFunction::eFixUpFixed }, + {"objc_msgSend_fpret", false, false, false, DispatchFunction::eFixUpNone }, + {"objc_msgSend_fpret_fixup", false, false, false, DispatchFunction::eFixUpToFix }, + {"objc_msgSend_fpret_fixedup", false, false, false, DispatchFunction::eFixUpFixed }, + {"objc_msgSend_fp2ret", false, false, true, DispatchFunction::eFixUpNone }, + {"objc_msgSend_fp2ret_fixup", false, false, true, DispatchFunction::eFixUpToFix }, + {"objc_msgSend_fp2ret_fixedup", false, false, true, DispatchFunction::eFixUpFixed }, + {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone }, + {"objc_msgSendSuper_stret", true, true, false, DispatchFunction::eFixUpNone }, + {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone }, + {"objc_msgSendSuper2_fixup", false, true, true, DispatchFunction::eFixUpToFix }, + {"objc_msgSendSuper2_fixedup", false, true, true, DispatchFunction::eFixUpFixed }, + {"objc_msgSendSuper2_stret", true, true, true, DispatchFunction::eFixUpNone }, + {"objc_msgSendSuper2_stret_fixup", true, true, true, DispatchFunction::eFixUpToFix }, + {"objc_msgSendSuper2_stret_fixedup", true, true, true, DispatchFunction::eFixUpFixed }, +}; + +AppleObjCTrampolineHandler::AppleObjCTrampolineHandler (const ProcessSP &process_sp, + const ModuleSP &objc_module_sp) : + m_process_wp (), + m_objc_module_sp (objc_module_sp), + m_impl_fn_addr (LLDB_INVALID_ADDRESS), + m_impl_stret_fn_addr (LLDB_INVALID_ADDRESS), + m_msg_forward_addr (LLDB_INVALID_ADDRESS) +{ + if (process_sp) + m_process_wp = process_sp; + // Look up the known resolution functions: + + ConstString get_impl_name("class_getMethodImplementation"); + ConstString get_impl_stret_name("class_getMethodImplementation_stret"); + ConstString msg_forward_name("_objc_msgForward"); + ConstString msg_forward_stret_name("_objc_msgForward_stret"); + + Target *target = process_sp ? &process_sp->GetTarget() : NULL; + const Symbol *class_getMethodImplementation = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_name, eSymbolTypeCode); + const Symbol *class_getMethodImplementation_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (get_impl_stret_name, eSymbolTypeCode); + const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType (msg_forward_name, eSymbolTypeCode); + const Symbol *msg_forward_stret = m_objc_module_sp->FindFirstSymbolWithNameAndType (msg_forward_stret_name, eSymbolTypeCode); + + if (class_getMethodImplementation) + m_impl_fn_addr = class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress (target); + if (class_getMethodImplementation_stret) + m_impl_stret_fn_addr = class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress (target); + if (msg_forward) + m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target); + if (msg_forward_stret) + m_msg_forward_stret_addr = msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target); + + // FIXME: Do some kind of logging here. + if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) + { + // If we can't even find the ordinary get method implementation function, then we aren't going to be able to + // step through any method dispatches. Warn to that effect and get out of here. + if (process_sp->CanJIT()) + { + process_sp->GetTarget().GetDebugger().GetErrorFile()->Printf ("Could not find implementation lookup function \"%s\"" + " step in through ObjC method dispatch will not work.\n", + get_impl_name.AsCString()); + } + return; + } + else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) + { + // It there is no stret return lookup function, assume that it is the same as the straight lookup: + m_impl_stret_fn_addr = m_impl_fn_addr; + // Also we will use the version of the lookup code that doesn't rely on the stret version of the function. + g_lookup_implementation_function_code = g_lookup_implementation_no_stret_function_code; + } + else + { + g_lookup_implementation_function_code = g_lookup_implementation_with_stret_function_code; + } + + // Look up the addresses for the objc dispatch functions and cache them. For now I'm inspecting the symbol + // names dynamically to figure out how to dispatch to them. If it becomes more complicated than this we can + // turn the g_dispatch_functions char * array into a template table, and populate the DispatchFunction map + // from there. + + for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) + { + ConstString name_const_str(g_dispatch_functions[i].name); + const Symbol *msgSend_symbol = m_objc_module_sp->FindFirstSymbolWithNameAndType (name_const_str, eSymbolTypeCode); + if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) + { + // FixMe: Make g_dispatch_functions static table of DispatchFunctions, and have the map be address->index. + // Problem is we also need to lookup the dispatch function. For now we could have a side table of stret & non-stret + // dispatch functions. If that's as complex as it gets, we're fine. + + lldb::addr_t sym_addr = msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target); + + m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i)); + } + } + + // Build our vtable dispatch handler here: + m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp)); + if (m_vtables_ap.get()) + m_vtables_ap->ReadRegions(); +} + +lldb::addr_t +AppleObjCTrampolineHandler::SetupDispatchFunction (Thread &thread, ValueList &dispatch_values) +{ + ExecutionContext exe_ctx (thread.shared_from_this()); + StreamString errors; + Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); + lldb::addr_t args_addr = LLDB_INVALID_ADDRESS; + FunctionCaller *impl_function_caller = nullptr; + + // Scope for mutex locker: + { + Mutex::Locker locker(m_impl_function_mutex); + + // First stage is to make the ClangUtility to hold our injected function: + + if (!m_impl_code.get()) + { + if (g_lookup_implementation_function_code != NULL) + { + Error error; + m_impl_code.reset (exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage (g_lookup_implementation_function_code, + eLanguageTypeObjC, + g_lookup_implementation_function_name, + error)); + if (error.Fail()) + { + if (log) + log->Printf ("Failed to get Utility Function for implementation lookup: %s.", error.AsCString()); + m_impl_code.reset(); + return args_addr; + } + + if (!m_impl_code->Install(errors, exe_ctx)) + { + if (log) + log->Printf ("Failed to install implementation lookup: %s.", errors.GetData()); + m_impl_code.reset(); + return args_addr; + } + } + else + { + if (log) + log->Printf("No method lookup implementation code."); + errors.Printf ("No method lookup implementation code found."); + return LLDB_INVALID_ADDRESS; + } + + + // Next make the runner function for our implementation utility function. + ClangASTContext *clang_ast_context = thread.GetProcess()->GetTarget().GetScratchClangASTContext(); + CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); + Error error; + + impl_function_caller = m_impl_code->MakeFunctionCaller(clang_void_ptr_type, + dispatch_values, + error); + if (error.Fail()) + { + if (log) + log->Printf ("Error getting function caller for dispatch lookup: \"%s\".", error.AsCString()); + return args_addr; + } + } + else + { + impl_function_caller = m_impl_code->GetFunctionCaller(); + } + } + + errors.Clear(); + + // Now write down the argument values for this particular call. This looks like it might be a race condition + // if other threads were calling into here, but actually it isn't because we allocate a new args structure for + // this call by passing args_addr = LLDB_INVALID_ADDRESS... + + if (impl_function_caller->WriteFunctionArguments (exe_ctx, args_addr, dispatch_values, errors)) + { + if (log) + log->Printf ("Error writing function arguments: \"%s\".", errors.GetData()); + return args_addr; + } + + return args_addr; +} + +ThreadPlanSP +AppleObjCTrampolineHandler::GetStepThroughDispatchPlan (Thread &thread, bool stop_others) +{ + ThreadPlanSP ret_plan_sp; + lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC(); + + DispatchFunction this_dispatch; + bool found_it = false; + + // First step is to look and see if we are in one of the known ObjC dispatch functions. We've already compiled + // a table of same, so consult it. + + MsgsendMap::iterator pos; + pos = m_msgSend_map.find (curr_pc); + if (pos != m_msgSend_map.end()) + { + this_dispatch = g_dispatch_functions[(*pos).second]; + found_it = true; + } + + // Next check to see if we are in a vtable region: + + if (!found_it) + { + uint32_t flags; + if (m_vtables_ap.get()) + { + found_it = m_vtables_ap->IsAddressInVTables (curr_pc, flags); + if (found_it) + { + this_dispatch.name = "vtable"; + this_dispatch.stret_return + = (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) == AppleObjCVTables::eOBJC_TRAMPOLINE_STRET; + this_dispatch.is_super = false; + this_dispatch.is_super2 = false; + this_dispatch.fixedup = DispatchFunction::eFixUpFixed; + } + } + } + + if (found_it) + { + Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP)); + + // We are decoding a method dispatch. + // First job is to pull the arguments out: + + lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0); + + const ABI *abi = NULL; + ProcessSP process_sp (thread.CalculateProcess()); + if (process_sp) + abi = process_sp->GetABI().get(); + if (abi == NULL) + return ret_plan_sp; + + TargetSP target_sp (thread.CalculateTarget()); + + ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext(); + ValueList argument_values; + Value void_ptr_value; + CompilerType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType(); + void_ptr_value.SetValueType (Value::eValueTypeScalar); + //void_ptr_value.SetContext (Value::eContextTypeClangType, clang_void_ptr_type); + void_ptr_value.SetCompilerType (clang_void_ptr_type); + + int obj_index; + int sel_index; + + // If this is a struct return dispatch, then the first argument is the + // return struct pointer, and the object is the second, and the selector is the third. + // Otherwise the object is the first and the selector the second. + if (this_dispatch.stret_return) + { + obj_index = 1; + sel_index = 2; + argument_values.PushValue(void_ptr_value); + argument_values.PushValue(void_ptr_value); + argument_values.PushValue(void_ptr_value); + } + else + { + obj_index = 0; + sel_index = 1; + argument_values.PushValue(void_ptr_value); + argument_values.PushValue(void_ptr_value); + } + + + bool success = abi->GetArgumentValues (thread, argument_values); + if (!success) + return ret_plan_sp; + + lldb::addr_t obj_addr = argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong(); + if (obj_addr == 0x0) + { + if (log) + log->Printf("Asked to step to dispatch to nil object, returning empty plan."); + return ret_plan_sp; + } + + ExecutionContext exe_ctx (thread.shared_from_this()); + Process *process = exe_ctx.GetProcessPtr(); + // isa_addr will store the class pointer that the method is being dispatched to - so either the class + // directly or the super class if this is one of the objc_msgSendSuper flavors. That's mostly used to + // look up the class/selector pair in our cache. + + lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS; + lldb::addr_t sel_addr = argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong(); + + // Figure out the class this is being dispatched to and see if we've already cached this method call, + // If so we can push a run-to-address plan directly. Otherwise we have to figure out where + // the implementation lives. + + if (this_dispatch.is_super) + { + if (this_dispatch.is_super2) + { + // In the objc_msgSendSuper2 case, we don't get the object directly, we get a structure containing + // the object and the class to which the super message is being sent. So we need to dig the super + // out of the class and use that. + + Value super_value(*(argument_values.GetValueAtIndex(obj_index))); + super_value.GetScalar() += process->GetAddressByteSize(); + super_value.ResolveValue (&exe_ctx); + + if (super_value.GetScalar().IsValid()) + { + + // isa_value now holds the class pointer. The second word of the class pointer is the super-class pointer: + super_value.GetScalar() += process->GetAddressByteSize(); + super_value.ResolveValue (&exe_ctx); + if (super_value.GetScalar().IsValid()) + isa_addr = super_value.GetScalar().ULongLong(); + else + { + if (log) + log->Printf("Failed to extract the super class value from the class in objc_super."); + } + } + else + { + if (log) + log->Printf("Failed to extract the class value from objc_super."); + } + } + else + { + // In the objc_msgSendSuper case, we don't get the object directly, we get a two element structure containing + // the object and the super class to which the super message is being sent. So the class we want is + // the second element of this structure. + + Value super_value(*(argument_values.GetValueAtIndex(obj_index))); + super_value.GetScalar() += process->GetAddressByteSize(); + super_value.ResolveValue (&exe_ctx); + + if (super_value.GetScalar().IsValid()) + { + isa_addr = super_value.GetScalar().ULongLong(); + } + else + { + if (log) + log->Printf("Failed to extract the class value from objc_super."); + } + } + } + else + { + // In the direct dispatch case, the object->isa is the class pointer we want. + + // This is a little cheesy, but since object->isa is the first field, + // making the object value a load address value and resolving it will get + // the pointer sized data pointed to by that value... + + // Note, it isn't a fatal error not to be able to get the address from the object, since this might + // be a "tagged pointer" which isn't a real object, but rather some word length encoded dingus. + + Value isa_value(*(argument_values.GetValueAtIndex(obj_index))); + + isa_value.SetValueType(Value::eValueTypeLoadAddress); + isa_value.ResolveValue(&exe_ctx); + if (isa_value.GetScalar().IsValid()) + { + isa_addr = isa_value.GetScalar().ULongLong(); + } + else + { + if (log) + log->Printf("Failed to extract the isa value from object."); + } + + } + + // Okay, we've got the address of the class for which we're resolving this, let's see if it's in our cache: + lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS; + + if (isa_addr != LLDB_INVALID_ADDRESS) + { + if (log) + { + log->Printf("Resolving call for class - 0x%" PRIx64 " and selector - 0x%" PRIx64, + isa_addr, sel_addr); + } + ObjCLanguageRuntime *objc_runtime = thread.GetProcess()->GetObjCLanguageRuntime (); + assert(objc_runtime != NULL); + + impl_addr = objc_runtime->LookupInMethodCache (isa_addr, sel_addr); + } + + if (impl_addr != LLDB_INVALID_ADDRESS) + { + // Yup, it was in the cache, so we can run to that address directly. + + if (log) + log->Printf ("Found implementation address in cache: 0x%" PRIx64, impl_addr); + + ret_plan_sp.reset (new ThreadPlanRunToAddress (thread, impl_addr, stop_others)); + } + else + { + // We haven't seen this class/selector pair yet. Look it up. + StreamString errors; + Address impl_code_address; + + ValueList dispatch_values; + + // We've will inject a little function in the target that takes the object, selector and some flags, + // and figures out the implementation. Looks like: + // void *__lldb_objc_find_implementation_for_selector (void *object, + // void *sel, + // int is_stret, + // int is_super, + // int is_super2, + // int is_fixup, + // int is_fixed, + // int debug) + // So set up the arguments for that call. + + dispatch_values.PushValue (*(argument_values.GetValueAtIndex(obj_index))); + dispatch_values.PushValue (*(argument_values.GetValueAtIndex(sel_index))); + + Value flag_value; + CompilerType clang_int_type = clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(lldb::eEncodingSint, 32); + flag_value.SetValueType (Value::eValueTypeScalar); + //flag_value.SetContext (Value::eContextTypeClangType, clang_int_type); + flag_value.SetCompilerType (clang_int_type); + + if (this_dispatch.stret_return) + flag_value.GetScalar() = 1; + else + flag_value.GetScalar() = 0; + dispatch_values.PushValue (flag_value); + + if (this_dispatch.is_super) + flag_value.GetScalar() = 1; + else + flag_value.GetScalar() = 0; + dispatch_values.PushValue (flag_value); + + if (this_dispatch.is_super2) + flag_value.GetScalar() = 1; + else + flag_value.GetScalar() = 0; + dispatch_values.PushValue (flag_value); + + switch (this_dispatch.fixedup) + { + case DispatchFunction::eFixUpNone: + flag_value.GetScalar() = 0; + dispatch_values.PushValue (flag_value); + dispatch_values.PushValue (flag_value); + break; + case DispatchFunction::eFixUpFixed: + flag_value.GetScalar() = 1; + dispatch_values.PushValue (flag_value); + flag_value.GetScalar() = 1; + dispatch_values.PushValue (flag_value); + break; + case DispatchFunction::eFixUpToFix: + flag_value.GetScalar() = 1; + dispatch_values.PushValue (flag_value); + flag_value.GetScalar() = 0; + dispatch_values.PushValue (flag_value); + break; + } + if (log && log->GetVerbose()) + flag_value.GetScalar() = 1; + else + flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done. + dispatch_values.PushValue (flag_value); + + + // The step through code might have to fill in the cache, so it is not safe to run only one thread. + // So we override the stop_others value passed in to us here: + const bool trampoline_stop_others = false; + ret_plan_sp.reset (new AppleThreadPlanStepThroughObjCTrampoline (thread, + this, + dispatch_values, + isa_addr, + sel_addr, + trampoline_stop_others)); + if (log) + { + StreamString s; + ret_plan_sp->GetDescription(&s, eDescriptionLevelFull); + log->Printf("Using ObjC step plan: %s.\n", s.GetData()); + } + } + } + + return ret_plan_sp; +} + +FunctionCaller * +AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller () +{ + return m_impl_code->GetFunctionCaller(); +} |