ThreadMachCore.cpp

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//===-- ThreadMachCore.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 <optional>
#include <string>
#include <vector>
 
#include "RegisterContextUnifiedCore.h"
#include "ThreadMachCore.h"
 
#include "lldb/Breakpoint/Watchpoint.h"
#include "lldb/Host/SafeMachO.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/AppleArm64ExceptionClass.h"
#include "lldb/Target/DynamicRegisterInfo.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StopInfo.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Unwind.h"
#include "lldb/Utility/ArchSpec.h"
#include "lldb/Utility/DataExtractor.h"
#include "lldb/Utility/RegisterValue.h"
#include "lldb/Utility/State.h"
#include "lldb/Utility/StreamString.h"
#include "lldb/Utility/StructuredData.h"
 
#include "ProcessMachCore.h"
//#include "RegisterContextKDP_arm.h"
//#include "RegisterContextKDP_i386.h"
//#include "RegisterContextKDP_x86_64.h"
 
using namespace lldb;
using namespace lldb_private;
 
// Thread Registers
 
ThreadMachCore::ThreadMachCore(Process &process, lldb::tid_t tid,
                               uint32_t objfile_lc_thread_idx)
    : Thread(process, tid), m_thread_name(), m_dispatch_queue_name(),
      m_thread_dispatch_qaddr(LLDB_INVALID_ADDRESS), m_thread_reg_ctx_sp(),
      m_objfile_lc_thread_idx(objfile_lc_thread_idx) {}
 
ThreadMachCore::~ThreadMachCore() { DestroyThread(); }
 
const char *ThreadMachCore::GetName() {
  if (m_thread_name.empty())
    return nullptr;
  return m_thread_name.c_str();
}
 
void ThreadMachCore::RefreshStateAfterStop() {
  // Invalidate all registers in our register context. We don't set "force" to
  // true because the stop reply packet might have had some register values
  // that were expedited and these will already be copied into the register
  // context by the time this function gets called. The KDPRegisterContext
  // class has been made smart enough to detect when it needs to invalidate
  // which registers are valid by putting hooks in the register read and
  // register supply functions where they check the process stop ID and do the
  // right thing.
  const bool force = false;
  GetRegisterContext()->InvalidateIfNeeded(force);
}
 
bool ThreadMachCore::ThreadIDIsValid(lldb::tid_t thread) { return thread != 0; }
 
lldb::RegisterContextSP ThreadMachCore::GetRegisterContext() {
  if (!m_reg_context_sp)
    m_reg_context_sp = CreateRegisterContextForFrame(nullptr);
  return m_reg_context_sp;
}
 
lldb::RegisterContextSP
ThreadMachCore::CreateRegisterContextForFrame(StackFrame *frame) {
  uint32_t concrete_frame_idx = 0;
 
  if (frame)
    concrete_frame_idx = frame->GetConcreteFrameIndex();
  if (concrete_frame_idx > 0)
    return GetUnwinder().CreateRegisterContextForFrame(frame);
 
  if (m_thread_reg_ctx_sp)
    return m_thread_reg_ctx_sp;
 
  ProcessSP process_sp(GetProcess());
  assert(process_sp);
 
  ObjectFile *core_objfile =
      static_cast<ProcessMachCore *>(process_sp.get())->GetCoreObjectFile();
  if (!core_objfile)
    return {};
 
  RegisterContextSP core_thread_regctx_sp =
      core_objfile->GetThreadContextAtIndex(m_objfile_lc_thread_idx, *this);
 
  if (!core_thread_regctx_sp)
    return {};
 
  StructuredData::ObjectSP process_md_sp =
      core_objfile->GetCorefileProcessMetadata();
 
  StructuredData::ObjectSP thread_md_sp;
  if (process_md_sp && process_md_sp->GetAsDictionary() &&
      process_md_sp->GetAsDictionary()->HasKey("threads")) {
    StructuredData::Array *threads = process_md_sp->GetAsDictionary()
                                         ->GetValueForKey("threads")
                                         ->GetAsArray();
    if (threads && threads->GetSize() == core_objfile->GetNumThreadContexts()) {
      StructuredData::ObjectSP thread_sp =
          threads->GetItemAtIndex(m_objfile_lc_thread_idx);
      if (thread_sp && thread_sp->GetAsDictionary())
        thread_md_sp = thread_sp;
    }
  }
  m_thread_reg_ctx_sp = std::make_shared<RegisterContextUnifiedCore>(
      *this, concrete_frame_idx, core_thread_regctx_sp, thread_md_sp);
 
  return m_thread_reg_ctx_sp;
}
 
static bool IsCrashExceptionClass(AppleArm64ExceptionClass EC) {
  switch (EC) {
  case AppleArm64ExceptionClass::ESR_EC_UNCATEGORIZED:
  case AppleArm64ExceptionClass::ESR_EC_SVC_32:
  case AppleArm64ExceptionClass::ESR_EC_SVC_64:
    // In the ARM exception model, a process takes an exception when asking the
    // kernel to service a system call. Don't treat this like a crash.
    return false;
  default:
    return true;
  }
}
 
bool ThreadMachCore::CalculateStopInfo() {
  ProcessSP process_sp(GetProcess());
  if (process_sp) {
    StopInfoSP stop_info;
    RegisterContextSP reg_ctx_sp = GetRegisterContext();
 
    if (reg_ctx_sp) {
      Target &target = process_sp->GetTarget();
      const ArchSpec arch_spec = target.GetArchitecture();
      const uint32_t cputype = arch_spec.GetMachOCPUType();
 
      if (cputype == llvm::MachO::CPU_TYPE_ARM64 ||
          cputype == llvm::MachO::CPU_TYPE_ARM64_32) {
        const RegisterInfo *esr_info = reg_ctx_sp->GetRegisterInfoByName("esr");
        const RegisterInfo *far_info = reg_ctx_sp->GetRegisterInfoByName("far");
        RegisterValue esr, far;
        if (reg_ctx_sp->ReadRegister(esr_info, esr) &&
            reg_ctx_sp->ReadRegister(far_info, far)) {
          const uint32_t esr_val = esr.GetAsUInt32();
          const AppleArm64ExceptionClass exception_class =
              getAppleArm64ExceptionClass(esr_val);
          if (IsCrashExceptionClass(exception_class)) {
            StreamString S;
            S.Printf("%s (fault address: 0x%" PRIx64 ")",
                     toString(exception_class), far.GetAsUInt64());
            stop_info =
                StopInfo::CreateStopReasonWithException(*this, S.GetData());
          }
        }
      }
    }
 
    // Set a stop reason for crashing threads only so that they get selected
    // preferentially.
    if (stop_info)
      SetStopInfo(stop_info);
    return true;
  }
  return false;
}