FPEAuditor.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
// FPEAuditor.cxx
// Implementation file for class FPEAuditor
// Author: S.Binet<binet@cern.ch>
 
#include <stdexcept>
#include <mutex>
#include <atomic>
 
// FrameWork includes
#include "GaudiKernel/INamedInterface.h"
#include "GaudiKernel/EventContext.h"
 
#include "FPEAuditor.h"
 
#include "CxxUtils/checker_macros.h"
 
// C includes
#include <fenv.h>
 
 
namespace FPEAudit {
  const int MAXARRAY=100;
  struct FPEAuditTLSData {
    void *s_array_O[MAXARRAY];
    void *s_array_I[MAXARRAY];
    void *s_array_D[MAXARRAY];
  };
 
  thread_local FPEAuditTLSData s_tlsdata;
 
  std::atomic<bool> s_handlerInstalled = false;
  std::atomic<bool> s_handlerDisabled = false;
  struct sigaction s_oldactHandler ATLAS_THREAD_SAFE;
 
  std::mutex s_mutex;
  typedef std::lock_guard<std::mutex> lock_t;
}
 
 
#if defined(__linux__) && ( defined(__i386__) || defined(__x86_64__) )
# include "FPEAudit_linux.icc"
#else
# include "FPEAudit_dummy.icc"
#endif
 

// Public methods:
 
// Constructors
FPEAuditor::FPEAuditor( const std::string& name,
            ISvcLocator* pSvcLocator ) :
  AthCommonMsg<Auditor>     ( name, pSvcLocator  ),
  m_CountFPEs(),
  m_env(),
  m_nexceptions(0)
{
  declareProperty("NStacktracesOnFPE", m_NstacktracesOnFPE,
                  "Flag to configure, how many stack traces in case of FPE are printed. "
                  "Default: Zero, just report that FPE has happened. "
                  "After collecting the stacktrace, the code has to modify the mcontext_t "
                  "struct to ignore FPEs for the rest of the processing of the algorithm/service "
                  "This part is highly non-portable!" );
 
  declareProperty("Nstacklines", m_Nstacklines,"Limit how deep we dive into the stack");
}
 
// Destructor
#include <fstream>
#include <iomanip>
FPEAuditor::~FPEAuditor()
{
  //m_msg << MSG::DEBUG << "Calling destructor" << endmsg;
}
 
StatusCode FPEAuditor::initialize()
{
  for ( unsigned int i(0); i<FPEAUDITOR_ARRAYSIZE; ++i )
    m_CountFPEs[i]=0;
  //ATH_MSG_INFO("==> initialize");
  // add a fake node here because we may come alive while the AuditorSvc is
  // still initializing (so one edge is left orphaned)
  add_fpe_node();
 
  return StatusCode::SUCCESS;
}
 
StatusCode FPEAuditor::finalize()
{
  ATH_MSG_INFO("FPE summary for this job");
  ATH_MSG_INFO(" FPE OVERFLOWs  : " << m_CountFPEs[FPEAUDITOR_OVERFLOW] );
  ATH_MSG_INFO(" FPE INVALIDs   : " << m_CountFPEs[FPEAUDITOR_INVALID]);
  ATH_MSG_INFO(" FPE DIVBYZEROs : " << m_CountFPEs[FPEAUDITOR_DIVBYZERO]);
 
  {
    FPEAudit::lock_t lock (FPEAudit::s_mutex);
    if ( FPEAudit::s_handlerInstalled && !FPEAudit::s_handlerDisabled )
      UninstallHandler();
  }
 
  return StatusCode::SUCCESS;
}
 
void FPEAuditor::InstallHandler()
{
  // Save the current FP environment.
  fegetenv (&m_env);
 
#ifdef __aarch64__
  ATH_MSG_WARNING("Collecting stack traces for FPES is not supported on aarch64");
  m_NstacktracesOnFPE = 0;
  FPEAudit::s_handlerDisabled = true;
  FPEAudit::s_handlerInstalled = true;
#else
  struct sigaction act;
  memset(&act, 0, sizeof act);
  act.sa_sigaction = FPEAudit::fpe_sig_action;
  act.sa_flags = SA_SIGINFO;
  if ( sigaction(SIGFPE, &act, &FPEAudit::s_oldactHandler) != 0 )
    {
      ATH_MSG_WARNING ("Printing stacktraces on FPE requested, but unable to install signal handler ! Switched off !");
      m_NstacktracesOnFPE=0;
    }
  if ( m_NstacktracesOnFPE )
    {
      ATH_MSG_INFO ("Installed Signalhandler !");
      FPEAudit::unmask_fpe();
    }
  FPEAudit::s_tlsdata.s_array_O[0]=NULL;
  FPEAudit::s_tlsdata.s_array_I[0]=NULL;
  FPEAudit::s_tlsdata.s_array_D[0]=NULL;
 
  FPEAudit::s_handlerInstalled = true;
#endif
}
 
void FPEAuditor::UninstallHandler()
{
  ATH_MSG_INFO("uninstalling SignalHandler");
  FPEAudit::s_handlerDisabled = true;
 
  feclearexcept(FE_ALL_EXCEPT);
  fesetenv (&m_env);
  FPEAudit::mask_fpe();
 
  // feenableexcept (0);
  // fedisableexcept (FE_ALL_EXCEPT);
}
 
void FPEAuditor::before(const std::string& event, const std::string& /*name*/,
                        const EventContext&)
{
  add_fpe_node();
 
  if ( event==IAuditor::Execute ) {
    if ( m_NstacktracesOnFPE && ! FPEAudit::s_handlerInstalled ) {
      FPEAudit::lock_t lock (FPEAudit::s_mutex);
      if ( m_NstacktracesOnFPE && ! FPEAudit::s_handlerInstalled ) {
        InstallHandler();
        m_nexceptions = m_NstacktracesOnFPE;
      }
    }
  }
}
 
void FPEAuditor::after(const std::string& event, const std::string& name,
                       const EventContext& ctx, const StatusCode&)
{
  report_fpe(event, name, ctx);
  pop_fpe_node();
 
  if ( event==IAuditor::Initialize ) {
    FPEAudit::lock_t lock (FPEAudit::s_mutex);
    // CoreDumpSvc can also install a FPE handler, grrr.
    if (name == "CoreDumpSvc") FPEAudit::s_handlerInstalled = false;
    if ( m_NstacktracesOnFPE && ! FPEAudit::s_handlerInstalled ) {
      InstallHandler();
      m_nexceptions = m_NstacktracesOnFPE;
    }
  }
}

void
FPEAuditor::report_fpe(const std::string& step,
                       const std::string& caller,
                       const EventContext& ctx)
{
  // store current list of FPE flags which were raised before
  int raised = fetestexcept(FE_OVERFLOW | FE_INVALID | FE_DIVBYZERO);
  if (raised) {
    std::stringstream evStr;
    if (ctx.valid()) {
      evStr << " on event " << ctx.eventID().event_number();
    }
 
    if (raised & FE_OVERFLOW) {
      ATH_MSG_WARNING("FPE OVERFLOW in [" << step << "] of [" << caller << "]" << evStr.str() <<
                      " " << m_NstacktracesOnFPE << " " << FPEAudit::s_tlsdata.s_array_O[0]
                      );
      ++m_CountFPEs[FPEAUDITOR_OVERFLOW];
      if ( m_NstacktracesOnFPE && FPEAudit::s_tlsdata.s_array_O[0] != NULL )
    {
      for (unsigned int j = 0; j < m_Nstacklines; j++)
        {
              FPEAudit::lock_t lock (FPEAudit::s_mutex);
          if (FPEAudit::s_tlsdata.s_array_O[j]==NULL) break;
          this->msg(MSG::INFO) << "FPE stacktrace " << j << " :\n";
          FPEAudit::resolve(FPEAudit::s_tlsdata.s_array_O[j],this->msg());
          FPEAudit::s_tlsdata.s_array_O[j]=NULL;
          this->msg(MSG::INFO) << endmsg;
        }
    }
    }
    if (raised & FE_INVALID) {
      ATH_MSG_WARNING("FPE INVALID in [" << step << "] of [" << caller << "]" << evStr.str()
                      << " " << m_NstacktracesOnFPE << " " << FPEAudit::s_tlsdata.s_array_I[0]
                      );
      ++m_CountFPEs[FPEAUDITOR_INVALID];
    }
    if ( m_NstacktracesOnFPE && FPEAudit::s_tlsdata.s_array_I[0] != NULL )
      {
    for (unsigned int j = 0; j < m_Nstacklines; j++)
      {
            FPEAudit::lock_t lock (FPEAudit::s_mutex);
            if (FPEAudit::s_tlsdata.s_array_I[j]==NULL) break;
        this->msg(MSG::INFO) << "FPE stacktrace " << j << " :\n";
        FPEAudit::resolve(FPEAudit::s_tlsdata.s_array_I[j],this->msg());
        FPEAudit::s_tlsdata.s_array_I[j]=NULL;
        this->msg(MSG::INFO) << endmsg;
      }
      }
    if (raised & FE_DIVBYZERO) {
      ATH_MSG_WARNING("FPE DIVBYZERO in [" << step << "] of [" << caller << "]" << evStr.str()
                      << " " << m_NstacktracesOnFPE << " " << FPEAudit::s_tlsdata.s_array_D[0]
                      );
      ++m_CountFPEs[FPEAUDITOR_DIVBYZERO];
      if ( m_NstacktracesOnFPE && FPEAudit::s_tlsdata.s_array_D[0] != NULL )
    {
          FPEAudit::lock_t lock (FPEAudit::s_mutex);
      for (unsigned int j = 0; j < m_Nstacklines; j++)
        {
          if (FPEAudit::s_tlsdata.s_array_D[j]==NULL) break;
          this->msg(MSG::INFO) << "FPE stacktrace " << j << " :\n";
          FPEAudit::resolve(FPEAudit::s_tlsdata.s_array_D[j],this->msg());
          FPEAudit::s_tlsdata.s_array_D[j]=NULL;
          this->msg(MSG::INFO) << endmsg;
        }
    }
    }
 
 
    FPEAudit::lock_t lock (FPEAudit::s_mutex);
    if ( --m_nexceptions == 0
         && FPEAudit::s_handlerInstalled &&
         !FPEAudit::s_handlerDisabled )
    {
      fprintf(stderr, "too many SIGFPE detected, will be uninstalling signal handler\n");
      UninstallHandler();
    }
  }
}
 
void
FPEAuditor::add_fpe_node()
{
  // clear FPE status word
  feclearexcept(FE_ALL_EXCEPT);
 
  if (FPEAudit::s_handlerDisabled) {
    // Make sure exceptions have been masked off if the handler has been
    // disabled.  Yes, this is already done in the signal handler.
    // But when TBB starts a new task, it resets the FPU control words
    // to values that were copied when the thread pool was initialized.
    // FIXME: Do it properly with TBB?  Not sure that the current
    // interfaces allow it.
    FPEAudit::mask_fpe();
  }
}
 
void
FPEAuditor::pop_fpe_node()
{
  if ( FPEAudit::s_handlerInstalled && !FPEAudit::s_handlerDisabled) {
    FPEAudit::unmask_fpe();
  }
}