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1e2c5481502b305d2e38ce94defffb43b82dbe3c
clang-p2996/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp
Jason Molenda 8d5a6007f9 Track transition from launch dyld to shared-cache dyld 
On macOS, a process will be launched with /usr/lib/dyld (the
dynamic linker) and the main binary by the kernel.  The
first thing the standalone dyld will do is call into the dyld
in the shared cache image.  This patch tracks the transition
between the dyld's at the very beginning of process startup.

In DynamicLoaderMacOS::NotifyBreakpointHit() there are two new
cases handled:

`dyld_image_dyld_moved` which is the launch /usr/lib/dyld indicating
that it is about call into the shared cache dyld ane evict itself.
lldb will remove the notification breakpoint it set, clear the binary
image list entirely, get the notification function pointer value out
of the dyld_all_image_infos struct (which is the notification fptr
in the to-be-run shared-cache dyld) and put an address breakpoint
there.

`dyld_notify_adding` is then called by shared-cache dyld, and we
detect this case by noticing that we have an empty binary image list,
normally impossibe, and treating this as if we'd just started a
process attach/launch.

Differential Revision: https://reviews.llvm.org/D127247
rdar://84222158
2022-06-07 13:34:30 -07:00

578 lines
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//===-- DynamicLoaderMacOS.cpp --------------------------------------------===//
//
// 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 "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Section.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/SymbolVendor.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/SectionLoadList.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/State.h"
#include "DynamicLoaderDarwin.h"
#include "DynamicLoaderMacOS.h"
#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
using namespace lldb;
using namespace lldb_private;
// Create an instance of this class. This function is filled into the plugin
// info class that gets handed out by the plugin factory and allows the lldb to
// instantiate an instance of this class.
DynamicLoader *DynamicLoaderMacOS::CreateInstance(Process *process,
bool force) {
bool create = force;
if (!create) {
create = true;
Module *exe_module = process->GetTarget().GetExecutableModulePointer();
if (exe_module) {
ObjectFile *object_file = exe_module->GetObjectFile();
if (object_file) {
create = (object_file->GetStrata() == ObjectFile::eStrataUser);
}
}
if (create) {
const llvm::Triple &triple_ref =
process->GetTarget().GetArchitecture().GetTriple();
switch (triple_ref.getOS()) {
case llvm::Triple::Darwin:
case llvm::Triple::MacOSX:
case llvm::Triple::IOS:
case llvm::Triple::TvOS:
case llvm::Triple::WatchOS:
// NEED_BRIDGEOS_TRIPLE case llvm::Triple::BridgeOS:
create = triple_ref.getVendor() == llvm::Triple::Apple;
break;
default:
create = false;
break;
}
}
}
if (!UseDYLDSPI(process)) {
create = false;
}
if (create)
return new DynamicLoaderMacOS(process);
return nullptr;
}
// Constructor
DynamicLoaderMacOS::DynamicLoaderMacOS(Process *process)
: DynamicLoaderDarwin(process), m_image_infos_stop_id(UINT32_MAX),
m_break_id(LLDB_INVALID_BREAK_ID),
m_dyld_handover_break_id(LLDB_INVALID_BREAK_ID), m_mutex(),
m_maybe_image_infos_address(LLDB_INVALID_ADDRESS) {}
// Destructor
DynamicLoaderMacOS::~DynamicLoaderMacOS() {
if (LLDB_BREAK_ID_IS_VALID(m_break_id))
m_process->GetTarget().RemoveBreakpointByID(m_break_id);
if (LLDB_BREAK_ID_IS_VALID(m_dyld_handover_break_id))
m_process->GetTarget().RemoveBreakpointByID(m_dyld_handover_break_id);
}
bool DynamicLoaderMacOS::ProcessDidExec() {
std::lock_guard<std::recursive_mutex> baseclass_guard(GetMutex());
bool did_exec = false;
if (m_process) {
// If we are stopped after an exec, we will have only one thread...
if (m_process->GetThreadList().GetSize() == 1) {
// Maybe we still have an image infos address around? If so see
// if that has changed, and if so we have exec'ed.
if (m_maybe_image_infos_address != LLDB_INVALID_ADDRESS) {
lldb::addr_t image_infos_address = m_process->GetImageInfoAddress();
if (image_infos_address != m_maybe_image_infos_address) {
// We don't really have to reset this here, since we are going to
// call DoInitialImageFetch right away to handle the exec. But in
// case anybody looks at it in the meantime, it can't hurt.
m_maybe_image_infos_address = image_infos_address;
did_exec = true;
}
}
if (!did_exec) {
// See if we are stopped at '_dyld_start'
ThreadSP thread_sp(m_process->GetThreadList().GetThreadAtIndex(0));
if (thread_sp) {
lldb::StackFrameSP frame_sp(thread_sp->GetStackFrameAtIndex(0));
if (frame_sp) {
const Symbol *symbol =
frame_sp->GetSymbolContext(eSymbolContextSymbol).symbol;
if (symbol) {
if (symbol->GetName() == "_dyld_start")
did_exec = true;
}
}
}
}
}
}
if (did_exec) {
m_libpthread_module_wp.reset();
m_pthread_getspecific_addr.Clear();
}
return did_exec;
}
// Clear out the state of this class.
void DynamicLoaderMacOS::DoClear() {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (LLDB_BREAK_ID_IS_VALID(m_break_id))
m_process->GetTarget().RemoveBreakpointByID(m_break_id);
if (LLDB_BREAK_ID_IS_VALID(m_dyld_handover_break_id))
m_process->GetTarget().RemoveBreakpointByID(m_dyld_handover_break_id);
m_break_id = LLDB_INVALID_BREAK_ID;
m_dyld_handover_break_id = LLDB_INVALID_BREAK_ID;
}
// Check if we have found DYLD yet
bool DynamicLoaderMacOS::DidSetNotificationBreakpoint() {
return LLDB_BREAK_ID_IS_VALID(m_break_id);
}
void DynamicLoaderMacOS::ClearNotificationBreakpoint() {
if (LLDB_BREAK_ID_IS_VALID(m_break_id)) {
m_process->GetTarget().RemoveBreakpointByID(m_break_id);
m_break_id = LLDB_INVALID_BREAK_ID;
}
}
// Try and figure out where dyld is by first asking the Process if it knows
// (which currently calls down in the lldb::Process to get the DYLD info
// (available on SnowLeopard only). If that fails, then check in the default
// addresses.
void DynamicLoaderMacOS::DoInitialImageFetch() {
Log *log = GetLog(LLDBLog::DynamicLoader);
// Remove any binaries we pre-loaded in the Target before
// launching/attaching. If the same binaries are present in the process,
// we'll get them from the shared module cache, we won't need to re-load them
// from disk.
UnloadAllImages();
StructuredData::ObjectSP all_image_info_json_sp(
m_process->GetLoadedDynamicLibrariesInfos());
ImageInfo::collection image_infos;
if (all_image_info_json_sp.get() &&
all_image_info_json_sp->GetAsDictionary() &&
all_image_info_json_sp->GetAsDictionary()->HasKey("images") &&
all_image_info_json_sp->GetAsDictionary()
->GetValueForKey("images")
->GetAsArray()) {
if (JSONImageInformationIntoImageInfo(all_image_info_json_sp,
image_infos)) {
LLDB_LOGF(log, "Initial module fetch: Adding %" PRId64 " modules.\n",
(uint64_t)image_infos.size());
UpdateSpecialBinariesFromNewImageInfos(image_infos);
AddModulesUsingImageInfos(image_infos);
}
}
m_dyld_image_infos_stop_id = m_process->GetStopID();
m_maybe_image_infos_address = m_process->GetImageInfoAddress();
}
bool DynamicLoaderMacOS::NeedToDoInitialImageFetch() { return true; }
// Static callback function that gets called when our DYLD notification
// breakpoint gets hit. We update all of our image infos and then let our super
// class DynamicLoader class decide if we should stop or not (based on global
// preference).
bool DynamicLoaderMacOS::NotifyBreakpointHit(void *baton,
StoppointCallbackContext *context,
lldb::user_id_t break_id,
lldb::user_id_t break_loc_id) {
// Let the event know that the images have changed
// DYLD passes three arguments to the notification breakpoint.
// Arg1: enum dyld_notify_mode mode - 0 = adding, 1 = removing, 2 = remove
// all Arg2: unsigned long icount - Number of shared libraries
// added/removed Arg3: uint64_t mach_headers[] - Array of load addresses
// of binaries added/removed
DynamicLoaderMacOS *dyld_instance = (DynamicLoaderMacOS *)baton;
ExecutionContext exe_ctx(context->exe_ctx_ref);
Process *process = exe_ctx.GetProcessPtr();
// This is a sanity check just in case this dyld_instance is an old dyld
// plugin's breakpoint still lying around.
if (process != dyld_instance->m_process)
return false;
if (dyld_instance->m_image_infos_stop_id != UINT32_MAX &&
process->GetStopID() < dyld_instance->m_image_infos_stop_id) {
return false;
}
const lldb::ABISP &abi = process->GetABI();
if (abi) {
// Build up the value array to store the three arguments given above, then
// get the values from the ABI:
TypeSystemClang *clang_ast_context =
ScratchTypeSystemClang::GetForTarget(process->GetTarget());
if (!clang_ast_context)
return false;
ValueList argument_values;
Value mode_value; // enum dyld_notify_mode { dyld_notify_adding=0,
// dyld_notify_removing=1, dyld_notify_remove_all=2 };
Value count_value; // unsigned long count
Value headers_value; // uint64_t machHeaders[] (aka void*)
CompilerType clang_void_ptr_type =
clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
CompilerType clang_uint32_type =
clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(
lldb::eEncodingUint, 32);
CompilerType clang_uint64_type =
clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(
lldb::eEncodingUint, 32);
mode_value.SetValueType(Value::ValueType::Scalar);
mode_value.SetCompilerType(clang_uint32_type);
if (process->GetTarget().GetArchitecture().GetAddressByteSize() == 4) {
count_value.SetValueType(Value::ValueType::Scalar);
count_value.SetCompilerType(clang_uint32_type);
} else {
count_value.SetValueType(Value::ValueType::Scalar);
count_value.SetCompilerType(clang_uint64_type);
}
headers_value.SetValueType(Value::ValueType::Scalar);
headers_value.SetCompilerType(clang_void_ptr_type);
argument_values.PushValue(mode_value);
argument_values.PushValue(count_value);
argument_values.PushValue(headers_value);
if (abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values)) {
uint32_t dyld_mode =
argument_values.GetValueAtIndex(0)->GetScalar().UInt(-1);
if (dyld_mode != static_cast<uint32_t>(-1)) {
// Okay the mode was right, now get the number of elements, and the
// array of new elements...
uint32_t image_infos_count =
argument_values.GetValueAtIndex(1)->GetScalar().UInt(-1);
if (image_infos_count != static_cast<uint32_t>(-1)) {
addr_t header_array =
argument_values.GetValueAtIndex(2)->GetScalar().ULongLong(-1);
if (header_array != static_cast<uint64_t>(-1)) {
std::vector<addr_t> image_load_addresses;
for (uint64_t i = 0; i < image_infos_count; i++) {
Status error;
addr_t addr = process->ReadUnsignedIntegerFromMemory(
header_array + (8 * i), 8, LLDB_INVALID_ADDRESS, error);
if (addr != LLDB_INVALID_ADDRESS) {
image_load_addresses.push_back(addr);
}
}
if (dyld_mode == 0) {
// dyld_notify_adding
if (process->GetTarget().GetImages().GetSize() == 0) {
// When all images have been removed, we're doing the
// dyld handover from a launch-dyld to a shared-cache-dyld,
// and we've just hit our one-shot address breakpoint in
// the sc-dyld. Note that the image addresses passed to
// this function are inferior sizeof(void*) not uint64_t's
// like our normal notification, so don't even look at
// image_load_addresses.
dyld_instance->ClearDYLDHandoverBreakpoint();
dyld_instance->DoInitialImageFetch();
dyld_instance->SetNotificationBreakpoint();
} else {
dyld_instance->AddBinaries(image_load_addresses);
}
} else if (dyld_mode == 1) {
// dyld_notify_removing
dyld_instance->UnloadImages(image_load_addresses);
} else if (dyld_mode == 2) {
// dyld_notify_remove_all
dyld_instance->UnloadAllImages();
} else if (dyld_mode == 3 && image_infos_count == 1) {
// dyld_image_dyld_moved
dyld_instance->ClearNotificationBreakpoint();
dyld_instance->UnloadAllImages();
dyld_instance->ClearDYLDModule();
process->GetTarget().GetImages().Clear();
process->GetTarget().GetSectionLoadList().Clear();
addr_t all_image_infos = process->GetImageInfoAddress();
int addr_size =
process->GetTarget().GetArchitecture().GetAddressByteSize();
addr_t notification_location = all_image_infos + 4 + // version
4 + // infoArrayCount
addr_size; // infoArray
Status error;
addr_t notification_addr =
process->ReadPointerFromMemory(notification_location, error);
if (ABISP abi_sp = process->GetABI())
notification_addr = abi_sp->FixCodeAddress(notification_addr);
dyld_instance->SetDYLDHandoverBreakpoint(notification_addr);
}
}
}
}
}
} else {
Target &target = process->GetTarget();
Debugger::ReportWarning(
"no ABI plugin located for triple " +
target.GetArchitecture().GetTriple().getTriple() +
": shared libraries will not be registered",
target.GetDebugger().GetID());
}
// Return true to stop the target, false to just let the target run
return dyld_instance->GetStopWhenImagesChange();
}
void DynamicLoaderMacOS::AddBinaries(
const std::vector<lldb::addr_t> &load_addresses) {
Log *log = GetLog(LLDBLog::DynamicLoader);
ImageInfo::collection image_infos;
LLDB_LOGF(log, "Adding %" PRId64 " modules.",
(uint64_t)load_addresses.size());
StructuredData::ObjectSP binaries_info_sp =
m_process->GetLoadedDynamicLibrariesInfos(load_addresses);
if (binaries_info_sp.get() && binaries_info_sp->GetAsDictionary() &&
binaries_info_sp->GetAsDictionary()->HasKey("images") &&
binaries_info_sp->GetAsDictionary()
->GetValueForKey("images")
->GetAsArray() &&
binaries_info_sp->GetAsDictionary()
->GetValueForKey("images")
->GetAsArray()
->GetSize() == load_addresses.size()) {
if (JSONImageInformationIntoImageInfo(binaries_info_sp, image_infos)) {
UpdateSpecialBinariesFromNewImageInfos(image_infos);
AddModulesUsingImageInfos(image_infos);
}
m_dyld_image_infos_stop_id = m_process->GetStopID();
}
}
// Dump the _dyld_all_image_infos members and all current image infos that we
// have parsed to the file handle provided.
void DynamicLoaderMacOS::PutToLog(Log *log) const {
if (log == nullptr)
return;
}
bool DynamicLoaderMacOS::SetNotificationBreakpoint() {
if (m_break_id == LLDB_INVALID_BREAK_ID) {
ModuleSP dyld_sp(GetDYLDModule());
if (dyld_sp) {
bool internal = true;
bool hardware = false;
LazyBool skip_prologue = eLazyBoolNo;
FileSpecList *source_files = nullptr;
FileSpecList dyld_filelist;
dyld_filelist.Append(dyld_sp->GetFileSpec());
Breakpoint *breakpoint =
m_process->GetTarget()
.CreateBreakpoint(&dyld_filelist, source_files,
"_dyld_debugger_notification",
eFunctionNameTypeFull, eLanguageTypeC, 0,
skip_prologue, internal, hardware)
.get();
breakpoint->SetCallback(DynamicLoaderMacOS::NotifyBreakpointHit, this,
true);
breakpoint->SetBreakpointKind("shared-library-event");
m_break_id = breakpoint->GetID();
}
}
return m_break_id != LLDB_INVALID_BREAK_ID;
}
bool DynamicLoaderMacOS::SetDYLDHandoverBreakpoint(
addr_t notification_address) {
if (m_dyld_handover_break_id == LLDB_INVALID_BREAK_ID) {
BreakpointSP dyld_handover_bp = m_process->GetTarget().CreateBreakpoint(
notification_address, true, false);
dyld_handover_bp->SetCallback(DynamicLoaderMacOS::NotifyBreakpointHit, this,
true);
dyld_handover_bp->SetOneShot(true);
m_dyld_handover_break_id = dyld_handover_bp->GetID();
return true;
}
return false;
}
void DynamicLoaderMacOS::ClearDYLDHandoverBreakpoint() {
if (LLDB_BREAK_ID_IS_VALID(m_dyld_handover_break_id))
m_process->GetTarget().RemoveBreakpointByID(m_dyld_handover_break_id);
m_dyld_handover_break_id = LLDB_INVALID_BREAK_ID;
}
addr_t
DynamicLoaderMacOS::GetDyldLockVariableAddressFromModule(Module *module) {
SymbolContext sc;
Target &target = m_process->GetTarget();
if (Symtab *symtab = module->GetSymtab()) {
std::vector<uint32_t> match_indexes;
ConstString g_symbol_name("_dyld_global_lock_held");
uint32_t num_matches = 0;
num_matches =
symtab->AppendSymbolIndexesWithName(g_symbol_name, match_indexes);
if (num_matches == 1) {
Symbol *symbol = symtab->SymbolAtIndex(match_indexes[0]);
if (symbol &&
(symbol->ValueIsAddress() || symbol->GetAddressRef().IsValid())) {
return symbol->GetAddressRef().GetOpcodeLoadAddress(&target);
}
}
}
return LLDB_INVALID_ADDRESS;
}
// Look for this symbol:
//
// int __attribute__((visibility("hidden"))) _dyld_global_lock_held =
// 0;
//
// in libdyld.dylib.
Status DynamicLoaderMacOS::CanLoadImage() {
Status error;
addr_t symbol_address = LLDB_INVALID_ADDRESS;
ConstString g_libdyld_name("libdyld.dylib");
Target &target = m_process->GetTarget();
const ModuleList &target_modules = target.GetImages();
std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex());
// Find any modules named "libdyld.dylib" and look for the symbol there first
for (ModuleSP module_sp : target.GetImages().ModulesNoLocking()) {
if (module_sp) {
if (module_sp->GetFileSpec().GetFilename() == g_libdyld_name) {
symbol_address = GetDyldLockVariableAddressFromModule(module_sp.get());
if (symbol_address != LLDB_INVALID_ADDRESS)
break;
}
}
}
// Search through all modules looking for the symbol in them
if (symbol_address == LLDB_INVALID_ADDRESS) {
for (ModuleSP module_sp : target.GetImages().Modules()) {
if (module_sp) {
addr_t symbol_address =
GetDyldLockVariableAddressFromModule(module_sp.get());
if (symbol_address != LLDB_INVALID_ADDRESS)
break;
}
}
}
// Default assumption is that it is OK to load images. Only say that we
// cannot load images if we find the symbol in libdyld and it indicates that
// we cannot.
if (symbol_address != LLDB_INVALID_ADDRESS) {
{
int lock_held =
m_process->ReadUnsignedIntegerFromMemory(symbol_address, 4, 0, error);
if (lock_held != 0) {
error.SetErrorString("dyld lock held - unsafe to load images.");
}
}
} else {
// If we were unable to find _dyld_global_lock_held in any modules, or it
// is not loaded into memory yet, we may be at process startup (sitting at
// _dyld_start) - so we should not allow dlopen calls. But if we found more
// than one module then we are clearly past _dyld_start so in that case
// we'll default to "it's safe".
if (target.GetImages().GetSize() <= 1)
error.SetErrorString("could not find the dyld library or "
"the dyld lock symbol");
}
return error;
}
bool DynamicLoaderMacOS::GetSharedCacheInformation(
lldb::addr_t &base_address, UUID &uuid, LazyBool &using_shared_cache,
LazyBool &private_shared_cache) {
base_address = LLDB_INVALID_ADDRESS;
uuid.Clear();
using_shared_cache = eLazyBoolCalculate;
private_shared_cache = eLazyBoolCalculate;
if (m_process) {
StructuredData::ObjectSP info = m_process->GetSharedCacheInfo();
StructuredData::Dictionary *info_dict = nullptr;
if (info.get() && info->GetAsDictionary()) {
info_dict = info->GetAsDictionary();
}
// {"shared_cache_base_address":140735683125248,"shared_cache_uuid
// ":"DDB8D70C-
// C9A2-3561-B2C8-BE48A4F33F96","no_shared_cache":false,"shared_cache_private_cache":false}
if (info_dict && info_dict->HasKey("shared_cache_uuid") &&
info_dict->HasKey("no_shared_cache") &&
info_dict->HasKey("shared_cache_base_address")) {
base_address = info_dict->GetValueForKey("shared_cache_base_address")
->GetIntegerValue(LLDB_INVALID_ADDRESS);
std::string uuid_str = std::string(
info_dict->GetValueForKey("shared_cache_uuid")->GetStringValue());
if (!uuid_str.empty())
uuid.SetFromStringRef(uuid_str);
if (!info_dict->GetValueForKey("no_shared_cache")->GetBooleanValue())
using_shared_cache = eLazyBoolYes;
else
using_shared_cache = eLazyBoolNo;
if (info_dict->GetValueForKey("shared_cache_private_cache")
->GetBooleanValue())
private_shared_cache = eLazyBoolYes;
else
private_shared_cache = eLazyBoolNo;
return true;
}
}
return false;
}
void DynamicLoaderMacOS::Initialize() {
PluginManager::RegisterPlugin(GetPluginNameStatic(),
GetPluginDescriptionStatic(), CreateInstance);
}
void DynamicLoaderMacOS::Terminate() {
PluginManager::UnregisterPlugin(CreateInstance);
}
llvm::StringRef DynamicLoaderMacOS::GetPluginDescriptionStatic() {
return "Dynamic loader plug-in that watches for shared library loads/unloads "
"in MacOSX user processes.";
}
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