cpu.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

 */

void _CPU_Context_restore(
  Context_Control  *next
)
{
  Context_Control_overlay *nextp = (Context_Control_overlay *)next;

  _CPU_ISR_Enable(nextp->isr_level);
  longjmp( nextp->regs, 0 );
}

/*PAGE
 *
 *  _CPU_Context_switch
 */

static void do_jump(
  Context_Control_overlay *currentp,
  Context_Control_overlay *nextp
);

void _CPU_Context_switch(
  Context_Control  *current,
  Context_Control  *next
)
{
  Context_Control_overlay *currentp = (Context_Control_overlay *)current;
  Context_Control_overlay *nextp = (Context_Control_overlay *)next;
#if 0
  int status;
#endif

  currentp->isr_level = _CPU_ISR_Disable_support();

  do_jump( currentp, nextp );

#if 0
  if (sigsetjmp(currentp->regs, 1) == 0) {    /* Save the current context */
     siglongjmp(nextp->regs, 0);           /* Switch to the new context */
     _Internal_error_Occurred(
         INTERNAL_ERROR_CORE,
         TRUE,
         status
       );
  }
#endif

#ifdef RTEMS_DEBUG
    if (_CPU_ISR_Get_level() == 0)
       abort();
#endif

  _CPU_ISR_Enable(currentp->isr_level);
}

static void do_jump(
  Context_Control_overlay *currentp,
  Context_Control_overlay *nextp
)
{
  int status;

  if (setjmp(currentp->regs) == 0) {    /* Save the current context */
     longjmp(nextp->regs, 0);           /* Switch to the new context */
     _Internal_error_Occurred(
         INTERNAL_ERROR_CORE,
         TRUE,
         status
       );
  }
}

/*PAGE
 *
 *  _CPU_Save_float_context
 */

void _CPU_Save_float_context(
  Context_Control_fp *fp_context
)
{
}

/*PAGE
 *
 *  _CPU_Restore_float_context
 */

void _CPU_Restore_float_context(
  Context_Control_fp *fp_context
)
{
}

/*PAGE
 *
 *  _CPU_ISR_Disable_support
 */

unsigned32 _CPU_ISR_Disable_support(void)
{
  int status;
  sigset_t  old_mask;

  sigemptyset( &old_mask );
  status = sigprocmask(SIG_BLOCK, &_CPU_Signal_mask, &old_mask);
  if ( status )
    _Internal_error_Occurred(
      INTERNAL_ERROR_CORE,
      TRUE,
      status
    );

  if (memcmp((void *)&posix_empty_mask, (void *)&old_mask, sizeof(sigset_t)))
    return 1;

  return 0;
}

/*PAGE
 *
 *  _CPU_ISR_Enable
 */

void _CPU_ISR_Enable(
  unsigned32 level
)
{
  int status;

  if (level == 0)
    status = sigprocmask(SIG_UNBLOCK, &_CPU_Signal_mask, 0);
  else
    status = sigprocmask(SIG_BLOCK, &_CPU_Signal_mask, 0);

  if ( status )
    _Internal_error_Occurred(
      INTERNAL_ERROR_CORE,
      TRUE,
      status
    );
}

/*PAGE
 *
 *  _CPU_ISR_Handler
 *
 *  External interrupt handler.
 *  This is installed as a UNIX signal handler.
 *  It vectors out to specific user interrupt handlers.
 */

void _CPU_ISR_Handler(int vector)
{
  extern void        _Thread_Dispatch(void);
  extern unsigned32  _Thread_Dispatch_disable_level;
  extern boolean     _Context_Switch_necessary;

  if (_ISR_Nest_level++ == 0) {
      /* switch to interrupt stack */
  }

  _Thread_Dispatch_disable_level++;

  if (_ISR_Vector_table[vector]) {
     _ISR_Vector_table[vector](vector);
  } else {
     _CPU_Stray_signal(vector);
  }

  if (_ISR_Nest_level-- == 0) {
      /* switch back to original stack */
  }

  _Thread_Dispatch_disable_level--;

  if (_Thread_Dispatch_disable_level == 0 &&
      (_Context_Switch_necessary || _ISR_Signals_to_thread_executing)) {
      _ISR_Signals_to_thread_executing = FALSE;
      _CPU_ISR_Enable(0);
      _Thread_Dispatch();
  }
}

/*PAGE
 *
 *  _CPU_Stray_signal
 */

void _CPU_Stray_signal(int sig_num)
{
  char buffer[ 4 ];

  /*
   * print "stray" msg about ones which that might mean something
   * Avoid using the stdio section of the library.
   * The following is generally safe.
   */

  switch (sig_num)
  {
#ifdef SIGCLD
      case SIGCLD:
          break;
#endif
      default:
      {
        /*
         *  We avoid using the stdio section of the library.
         *  The following is generally safe
         */

        int digit;
        int number = sig_num;
        int len = 0;

        digit = number / 100;
        number %= 100;
        if (digit) buffer[len++] = '0' + digit;

        digit = number / 10;
        number %= 10;
        if (digit || len) buffer[len++] = '0' + digit;

        digit = number;
        buffer[len++] = '0' + digit;

        buffer[ len++ ] = '\n';

        write( 2, "Stray signal ", 13 );
        write( 2, buffer, len );

      }
  }

  /*
   * If it was a "fatal" signal, then exit here
   * If app code has installed a hander for one of these, then
   * we won't call _CPU_Stray_signal, so this is ok.
   */

  switch (sig_num) {
      case SIGINT:
      case SIGHUP:
      case SIGQUIT:
      case SIGILL:
#ifdef SIGEMT
      case SIGEMT:
#endif
      case SIGKILL:
      case SIGBUS:
      case SIGSEGV:
      case SIGTERM:
#if !defined(__CYGWIN__)
      case SIGIOT:
#endif
        _CPU_Fatal_error(0x100 + sig_num);
  }
}

/*PAGE
 *
 *  _CPU_Fatal_error
 */

void _CPU_Fatal_error(unsigned32 error)
{
  setitimer(ITIMER_REAL, 0, 0);

  if ( error ) {
#ifdef RTEMS_DEBUG
    abort();
#endif
    if (getenv("RTEMS_DEBUG"))
      abort();
  }

  _exit(error);
}

/*
 *  Special Purpose Routines to hide the use of UNIX system calls.
 */

int _CPU_Set_sync_io_handler(
  int fd,
  boolean read,
  boolean write,
  boolean except,
  rtems_sync_io_handler handler
)
{
  if ((fd < FD_SETSIZE) && (_CPU_Sync_io_handlers[fd] == NULL)) {
    if (read)
      FD_SET(fd, &sync_io_readfds);
    else
      FD_CLR(fd, &sync_io_readfds);
    if (write)
      FD_SET(fd, &sync_io_writefds);
    else
      FD_CLR(fd, &sync_io_writefds);
    if (except)
      FD_SET(fd, &sync_io_exceptfds);
    else
      FD_CLR(fd, &sync_io_exceptfds);
    _CPU_Sync_io_handlers[fd] = handler;
    if ((fd + 1) > sync_io_nfds)
      sync_io_nfds = fd + 1;
    return 0;
  }
  return -1;
}

int _CPU_Clear_sync_io_handler(
  int fd
)
{
  if ((fd < FD_SETSIZE) && _CPU_Sync_io_handlers[fd]) {
    FD_CLR(fd, &sync_io_readfds);
    FD_CLR(fd, &sync_io_writefds);
    FD_CLR(fd, &sync_io_exceptfds);
    _CPU_Sync_io_handlers[fd] = NULL;
    sync_io_nfds = 0;
    for (fd = 0; fd < FD_SETSIZE; fd++)
      if (FD_ISSET(fd, &sync_io_readfds) ||
          FD_ISSET(fd, &sync_io_writefds) ||
          FD_ISSET(fd, &sync_io_exceptfds))
        sync_io_nfds = fd + 1;
    return 0;
  }
  return -1;
}

int _CPU_Get_clock_vector( void )
{
  return SIGALRM;
}

void _CPU_Start_clock(
  int microseconds
)
{
  struct itimerval  new;

  new.it_value.tv_sec = 0;
  new.it_value.tv_usec = microseconds;
  new.it_interval.tv_sec = 0;
  new.it_interval.tv_usec = microseconds;

  setitimer(ITIMER_REAL, &new, 0);
}

void _CPU_Stop_clock( void )
{
  struct itimerval  new;
  struct sigaction  act;

  /*
   * Set the SIGALRM signal to ignore any last
   * signals that might come in while we are
   * disarming the timer and removing the interrupt
   * vector.
   */

  (void) memset(&act, 0, sizeof(act));
  act.sa_handler = SIG_IGN;

  sigaction(SIGALRM, &act, 0);

  (void) memset(&new, 0, sizeof(new));
  setitimer(ITIMER_REAL, &new, 0);
}

#if 0
extern void fix_syscall_errno( void );
#endif
#define fix_syscall_errno() 

#if defined(RTEMS_MULTIPROCESSING)
int  _CPU_SHM_Semid;

void _CPU_SHM_Init(
  unsigned32   maximum_nodes,
  boolean      is_master_node,
  void       **shm_address,
  unsigned32  *shm_length
)
{
  int          i;
  int          shmid;
  char        *shm_addr;
  key_t        shm_key;
  key_t        sem_key;
  int          status = 0;  /* to avoid unitialized warnings */
  int          shm_size;

  if (getenv("RTEMS_SHM_KEY"))
    shm_key = strtol(getenv("RTEMS_SHM_KEY"), 0, 0);
  else
#ifdef RTEMS_SHM_KEY
    shm_key = RTEMS_SHM_KEY;
#else
    shm_key = 0xa000;
#endif

    if (getenv("RTEMS_SHM_SIZE"))
      shm_size = strtol(getenv("RTEMS_SHM_SIZE"), 0, 0);
    else
#ifdef RTEMS_SHM_SIZE
      shm_size = RTEMS_SHM_SIZE;
#else
      shm_size = 64 * 1024;
#endif

    if (getenv("RTEMS_SHM_SEMAPHORE_KEY"))
      sem_key = strtol(getenv("RTEMS_SHM_SEMAPHORE_KEY"), 0, 0);
    else
#ifdef RTEMS_SHM_SEMAPHORE_KEY
      sem_key = RTEMS_SHM_SEMAPHORE_KEY;
#else
      sem_key = 0xa001;
#endif

    shmid = shmget(shm_key, shm_size, IPC_CREAT | 0660);
    if ( shmid == -1 ) {
      fix_syscall_errno(); /* in case of newlib */
      perror( "shmget" );
      _CPU_Fatal_halt( 0xdead0001 );
    }

    shm_addr = shmat(shmid, (char *)0, SHM_RND);
    if ( shm_addr == (void *)-1 ) {
      fix_syscall_errno(); /* in case of newlib */
      perror( "shmat" );
      _CPU_Fatal_halt( 0xdead0002 );
    }

    _CPU_SHM_Semid = semget(sem_key, maximum_nodes + 1, IPC_CREAT | 0660);
    if ( _CPU_SHM_Semid == -1 ) {
      fix_syscall_errno(); /* in case of newlib */
      perror( "semget" );
      _CPU_Fatal_halt( 0xdead0003 );
    }

    if ( is_master_node ) {
      for ( i=0 ; i <= maximum_nodes ; i++ ) {
#if !HAS_UNION_SEMUN
        union semun {
          int val;
          struct semid_ds *buf;
          unsigned short int *array;
#if defined(__linux__)
          struct seminfo *__buf;
#endif          
        } ;
#endif
        union semun help ;
        help.val = 1;
        status = semctl( _CPU_SHM_Semid, i, SETVAL, help );

        fix_syscall_errno(); /* in case of newlib */
        if ( status == -1 ) {
          _CPU_Fatal_halt( 0xdead0004 );
        }
      }
    }

  *shm_address = shm_addr;
  *shm_length = shm_size;

}
#endif

int _CPU_Get_pid( void )
{
  return getpid();
}

#if defined(RTEMS_MULTIPROCESSING)
/*
 * Define this to use signals for MPCI shared memory driver.
 * If undefined, the shared memory driver will poll from the
 * clock interrupt.
 * Ref: ../shmsupp/getcfg.c
 *
 * BEWARE:: many UN*X kernels and debuggers become severely confused when
 *          debugging programs which use signals.  The problem is *much*
 *          worse when using multiple signals, since ptrace(2) tends to
 *          drop all signals except 1 in the case of multiples.
 *          On hpux9, this problem was so bad, we couldn't use interrupts
 *          with the shared memory driver if we ever hoped to debug
 *          RTEMS programs.
 *          Maybe systems that use /proc don't have this problem...
 */


int _CPU_SHM_Get_vector( void )
{
#ifdef CPU_USE_SHM_INTERRUPTS
  return SIGUSR1;
#else
  return 0;
#endif
}

void _CPU_SHM_Send_interrupt(
  int pid,
  int vector
)
{
  kill((pid_t) pid, vector);
}

void _CPU_SHM_Lock(
  int semaphore
)
{
  struct sembuf sb;

  sb.sem_num = semaphore;
  sb.sem_op  = -1;
  sb.sem_flg = 0;

  while (1) {
    int status = -1;

    status = semop(_CPU_SHM_Semid, &sb, 1);
    if ( status >= 0 )
      break;
    if ( status == -1 ) {
       fix_syscall_errno();    /* in case of newlib */
        if (errno == EINTR)
            continue;
        perror("shm lock");
        _CPU_Fatal_halt( 0xdead0005 );
    }
  }

}

void _CPU_SHM_Unlock(
  int semaphore
)
{
  struct sembuf  sb;
  int            status;

  sb.sem_num = semaphore;
  sb.sem_op  = 1;
  sb.sem_flg = 0;

  while (1) {
    status = semop(_CPU_SHM_Semid, &sb, 1);
    if ( status >= 0 )
      break;

    if ( status == -1 ) {
      fix_syscall_errno();    /* in case of newlib */
      if (errno == EINTR)
          continue;
      perror("shm unlock");
      _CPU_Fatal_halt( 0xdead0006 );
    }
  }

}
#endif