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path: root/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp
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-rw-r--r--lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp1145
1 files changed, 1145 insertions, 0 deletions
diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp
new file mode 100644
index 0000000000000..379ef3dca86c9
--- /dev/null
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp
@@ -0,0 +1,1145 @@
+//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++
+//-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "AppleObjCTrampolineHandler.h"
+#include "AppleThreadPlanStepThroughObjCTrampoline.h"
+
+#include "lldb/Breakpoint/StoppointCallbackContext.h"
+#include "lldb/Core/Debugger.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/StreamFile.h"
+#include "lldb/Core/Value.h"
+#include "lldb/Expression/DiagnosticManager.h"
+#include "lldb/Expression/FunctionCaller.h"
+#include "lldb/Expression/UserExpression.h"
+#include "lldb/Expression/UtilityFunction.h"
+#include "lldb/Symbol/ClangASTContext.h"
+#include "lldb/Symbol/Symbol.h"
+#include "lldb/Target/ABI.h"
+#include "lldb/Target/ExecutionContext.h"
+#include "lldb/Target/Process.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/ThreadPlanRunToAddress.h"
+#include "lldb/Utility/ConstString.h"
+#include "lldb/Utility/FileSpec.h"
+#include "lldb/Utility/Log.h"
+
+#include "llvm/ADT/STLExtras.h"
+
+#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
+
+#include <memory>
+
+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_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, \n\
+ 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 ( \n\
+ 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 *receiver; \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\
+ \n\
+ // The call to [object class] is here because if this is a \n\
+ // class, and has not been called into yet, we need to do \n\
+ // something to force the class to initialize itself. \n\
+ // Then the call to object_getClass will actually return the \n\
+ // correct class, either the class if object is a class \n\
+ // 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 = \n\
+ class_getMethodImplementation_stret (return_struct.class_addr, \n\
+ return_struct.sel_addr); \n\
+ } \n\
+ else \n\
+ { \n\
+ return_struct.impl_addr = \n\
+ class_getMethodImplementation (return_struct.class_addr, \n\
+ return_struct.sel_addr); \n\
+ } \n\
+ if (debug) \n\
+ printf (\"\\n*** Returning implementation: %p.\\n\", \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 *receiver; \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 = \n\
+ class_getMethodImplementation (return_struct.class_addr, \n\
+ return_struct.sel_addr); \n\
+ if (debug) \n\
+ printf (\"\\n*** Returning implementation: 0x%p.\\n\", \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();
+ Status 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();
+ std::lock_guard<std::recursive_mutex> guard(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 (ObjCLanguageRuntime::Get(*process_sp)
+ ->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 != nullptr) {
+ 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 != nullptr) {
+ 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.
+ Status error;
+ DataExtractor data;
+ error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data,
+ nullptr);
+ 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;
+ Status 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);
+ LLDB_LOGF(log, "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_lookup_implementation_function_code(nullptr),
+ 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() : nullptr;
+ 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().GetErrorStream().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.
+ m_lookup_implementation_function_code =
+ g_lookup_implementation_no_stret_function_code;
+ } else {
+ m_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_up.reset(new AppleObjCVTables(process_sp, m_objc_module_sp));
+ if (m_vtables_up)
+ m_vtables_up->ReadRegions();
+}
+
+lldb::addr_t
+AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread,
+ ValueList &dispatch_values) {
+ ThreadSP thread_sp(thread.shared_from_this());
+ ExecutionContext exe_ctx(thread_sp);
+ DiagnosticManager diagnostics;
+ 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:
+ {
+ std::lock_guard<std::mutex> guard(m_impl_function_mutex);
+
+ // First stage is to make the ClangUtility to hold our injected function:
+
+ if (!m_impl_code) {
+ if (m_lookup_implementation_function_code != nullptr) {
+ Status error;
+ m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage(
+ m_lookup_implementation_function_code, eLanguageTypeObjC,
+ g_lookup_implementation_function_name, error));
+ if (error.Fail()) {
+ LLDB_LOGF(
+ log,
+ "Failed to get Utility Function for implementation lookup: %s.",
+ error.AsCString());
+ m_impl_code.reset();
+ return args_addr;
+ }
+
+ if (!m_impl_code->Install(diagnostics, exe_ctx)) {
+ if (log) {
+ LLDB_LOGF(log, "Failed to install implementation lookup.");
+ diagnostics.Dump(log);
+ }
+ m_impl_code.reset();
+ return args_addr;
+ }
+ } else {
+ LLDB_LOGF(log, "No method lookup implementation code.");
+ 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();
+ Status error;
+
+ impl_function_caller = m_impl_code->MakeFunctionCaller(
+ clang_void_ptr_type, dispatch_values, thread_sp, error);
+ if (error.Fail()) {
+ LLDB_LOGF(log,
+ "Error getting function caller for dispatch lookup: \"%s\".",
+ error.AsCString());
+ return args_addr;
+ }
+ } else {
+ impl_function_caller = m_impl_code->GetFunctionCaller();
+ }
+ }
+
+ diagnostics.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, diagnostics)) {
+ if (log) {
+ LLDB_LOGF(log, "Error writing function arguments.");
+ diagnostics.Dump(log);
+ }
+ 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_up) {
+ found_it = m_vtables_up->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 = nullptr;
+ ProcessSP process_sp(thread.CalculateProcess());
+ if (process_sp)
+ abi = process_sp->GetABI().get();
+ if (abi == nullptr)
+ 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) {
+ LLDB_LOGF(
+ log,
+ "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 {
+ LLDB_LOGF(log, "Failed to extract the super class value from the "
+ "class in objc_super.");
+ }
+ } else {
+ LLDB_LOGF(log, "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 {
+ LLDB_LOGF(log, "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 {
+ LLDB_LOGF(log, "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) {
+ LLDB_LOGF(log,
+ "Resolving call for class - 0x%" PRIx64
+ " and selector - 0x%" PRIx64,
+ isa_addr, sel_addr);
+ }
+ ObjCLanguageRuntime *objc_runtime =
+ ObjCLanguageRuntime::Get(*thread.GetProcess());
+ assert(objc_runtime != nullptr);
+
+ 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.
+
+ LLDB_LOGF(log, "Found implementation address in cache: 0x%" PRIx64,
+ impl_addr);
+
+ ret_plan_sp = std::make_shared<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 = std::make_shared<AppleThreadPlanStepThroughObjCTrampoline>(
+ thread, this, dispatch_values, isa_addr, sel_addr,
+ trampoline_stop_others);
+ if (log) {
+ StreamString s;
+ ret_plan_sp->GetDescription(&s, eDescriptionLevelFull);
+ LLDB_LOGF(log, "Using ObjC step plan: %s.\n", s.GetData());
+ }
+ }
+ }
+
+ return ret_plan_sp;
+}
+
+FunctionCaller *
+AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() {
+ return m_impl_code->GetFunctionCaller();
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 06:31:03 +0000