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glibc  2.9
Defines | Functions
sigreturn.c File Reference
#include <hurd.h>
#include <hurd/signal.h>
#include <hurd/threadvar.h>
#include <hurd/msg.h>
#include <stdlib.h>
#include <string.h>

Go to the source code of this file.


#define A(line)   asm volatile (#line)


register int *sp asm ("%esp")
int __sigreturn (struct sigcontext *scp)

Define Documentation

#define A (   line)    asm volatile (#line)

Function Documentation

int __sigreturn ( struct sigcontext scp)

Definition at line 29 of file sigreturn.c.

  struct hurd_sigstate *ss;
  struct hurd_userlink *link = (void *) &scp[1];
  mach_port_t *reply_port;

  if (scp == NULL || (scp->sc_mask & _SIG_CANT_MASK))
      errno = EINVAL;
      return -1;

  ss = _hurd_self_sigstate ();
  __spin_lock (&ss->lock);

  /* Remove the link on the `active resources' chain added by
     _hurd_setup_sighandler.  Its purpose was to make sure
     that we got called; now we have, it is done.  */
  _hurd_userlink_unlink (link);

  /* Restore the set of blocked signals, and the intr_port slot.  */
  ss->blocked = scp->sc_mask;
  ss->intr_port = scp->sc_intr_port;

  /* Check for pending signals that were blocked by the old set.  */
  if (ss->pending & ~ss->blocked)
      /* There are pending signals that just became unblocked.  Wake up the
        signal thread to deliver them.  But first, squirrel away SCP where
        the signal thread will notice it if it runs another handler, and
        arrange to have us called over again in the new reality.  */
      ss->context = scp;
      __spin_unlock (&ss->lock);
      __msg_sig_post (_hurd_msgport, 0, 0, __mach_task_self ());
      /* If a pending signal was handled, sig_post never returned.
        If it did return, the pending signal didn't run a handler;
        proceed as usual.  */
      __spin_lock (&ss->lock);
      ss->context = NULL;

  if (scp->sc_onstack)
      ss->sigaltstack.ss_flags &= ~SS_ONSTACK; /* XXX threadvars */
      /* XXX cannot unlock until off sigstack */
      abort ();
    __spin_unlock (&ss->lock);

  /* Destroy the MiG reply port used by the signal handler, and restore the
     reply port in use by the thread when interrupted.  */
  reply_port =
    (mach_port_t *) __hurd_threadvar_location (_HURD_THREADVAR_MIG_REPLY);
  if (*reply_port)
      mach_port_t port = *reply_port;

      /* Assigning MACH_PORT_DEAD here tells libc's mig_get_reply_port not to
        get another reply port, but avoids mig_dealloc_reply_port trying to
        deallocate it after the receive fails (which it will, because the
        reply port will be bogus, whether we do this or not).  */
      *reply_port = MACH_PORT_DEAD;

      __mach_port_destroy (__mach_task_self (), port);
  *reply_port = scp->sc_reply_port;

  if (scp->sc_fpused)
    /* Restore the FPU state.  Mach conveniently stores the state
       in the format the i387 `frstor' instruction uses to restore it.  */
    asm volatile ("frstor %0" : : "m" (scp->sc_fpsave));

    /* There are convenient instructions to pop state off the stack, so we
       copy the registers onto the user's stack, switch there, pop and
       return.  */

    int *usp = (int *) scp->sc_uesp;

    *--usp = scp->sc_eip;
    *--usp = scp->sc_efl;
    memcpy (usp -= 12, &scp->sc_i386_thread_state, 12 * sizeof (int));

    sp = usp;

#define A(line) asm volatile (#line)
    /* The members in the sigcontext are arranged in this order
       so we can pop them easily.  */

    /* Pop the segment registers (except %cs and %ss, done last).  */
    A (popl %gs);
    A (popl %fs);
    A (popl %es);
    A (popl %ds);
    /* Pop the general registers.  */
    A (popa);
    /* Pop the processor flags.  */
    A (popf);
    /* Return to the saved PC.  */
    A (ret);

    /* Firewall.  */
    A (hlt);
#undef A

  return -1;

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register int* sp asm ( "%esp"  )