From 8d5a6007f9681ded3e6442bafdea87e733d771ea Mon Sep 17 00:00:00 2001 From: Jason Molenda Date: Tue, 7 Jun 2022 13:27:16 -0700 Subject: [PATCH] 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 --- .../MacOSX-DYLD/DynamicLoaderDarwin.cpp | 2 + .../MacOSX-DYLD/DynamicLoaderDarwin.h | 2 + .../MacOSX-DYLD/DynamicLoaderMacOS.cpp | 68 +++++++++++++++++++++- .../DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.h | 5 ++ 4 files changed, 75 insertions(+), 2 deletions(-) diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp index 033394b..043504b 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp @@ -611,6 +611,8 @@ ModuleSP DynamicLoaderDarwin::GetDYLDModule() { return dyld_sp; } +void DynamicLoaderDarwin::ClearDYLDModule() { m_dyld_module_wp.reset(); } + bool DynamicLoaderDarwin::AddModulesUsingImageInfos( ImageInfo::collection &image_infos) { std::lock_guard guard(m_mutex); diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.h b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.h index 1b705e9..5a72de2 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.h +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.h @@ -71,6 +71,8 @@ protected: lldb::ModuleSP GetDYLDModule(); + void ClearDYLDModule(); + class Segment { public: Segment() : name() {} diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp index e6bcc4c..63b0b96 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp @@ -14,6 +14,7 @@ #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" @@ -76,13 +77,16 @@ DynamicLoader *DynamicLoaderMacOS::CreateInstance(Process *process, // Constructor DynamicLoaderMacOS::DynamicLoaderMacOS(Process *process) : DynamicLoaderDarwin(process), m_image_infos_stop_id(UINT32_MAX), - m_break_id(LLDB_INVALID_BREAK_ID), m_mutex(), + 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() { @@ -135,8 +139,11 @@ void DynamicLoaderMacOS::DoClear() { 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 @@ -286,13 +293,50 @@ bool DynamicLoaderMacOS::NotifyBreakpointHit(void *baton, } if (dyld_mode == 0) { // dyld_notify_adding - dyld_instance->AddBinaries(image_load_addresses); + 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); } } } @@ -371,6 +415,26 @@ bool DynamicLoaderMacOS::SetNotificationBreakpoint() { 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; diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.h b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.h index a179679..b6e4ce8 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.h +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.h @@ -71,6 +71,10 @@ protected: bool DidSetNotificationBreakpoint() override; + bool SetDYLDHandoverBreakpoint(lldb::addr_t notification_address); + + void ClearDYLDHandoverBreakpoint(); + void AddBinaries(const std::vector &load_addresses); void DoClear() override; @@ -94,6 +98,7 @@ protected: uint32_t m_image_infos_stop_id; // The Stop ID the last time we // loaded/unloaded images lldb::user_id_t m_break_id; + lldb::user_id_t m_dyld_handover_break_id; mutable std::recursive_mutex m_mutex; lldb::addr_t m_maybe_image_infos_address; // If dyld is still maintaining the // all_image_infos address, store it -- 2.7.4