initial import

6 files changed, 718 insertions, 0 deletions

diff --git a/sysdeps/mach/hurd/alpha/exc2signal.c b/sysdeps/mach/hurd/alpha/exc2signal.c
new file mode 100644
index 0000000000..edac0aaa67
--- /dev/null
+++ b/sysdeps/mach/hurd/alpha/exc2signal.c
@@ -0,0 +1,76 @@
+/* Translate Mach exception codes into signal numbers.  Alpha version.
+Copyright (C) 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <hurd.h>
+#include <hurd/signal.h>
+#include <mach/exception.h>
+
+/* Translate the Mach exception codes, as received in an `exception_raise' RPC,
+   into a signal number and signal subcode.  */
+
+void
+_hurd_exception2signal (int exception, int code, int subcode,
+			int *signo, long int *sigcode, int *error)
+{
+  *error = 0;
+
+  switch (exception)
+    {
+    default:
+      *signo = SIGIOT;
+      *sigcode = exception;
+      break;
+      
+    case EXC_BAD_ACCESS:
+      if (code == KERN_PROTECTION_FAILURE)
+	*signo = SIGSEGV;
+      else
+	*signo = SIGBUS;
+      *sigcode = subcode;
+      *error = code;
+      break;
+
+    case EXC_BAD_INSTRUCTION:
+      *signo = SIGILL;
+      *sigcode = code;
+      break;
+      
+    case EXC_ARITHMETIC:
+      *signo = SIGFPE;
+      *sigcode = code;
+      break;
+      break;
+
+    case EXC_EMULATION:		
+      /* 3.0 doesn't give this one, why, I don't know.  */
+      *signo = SIGEMT;
+      *sigcode = code;
+      break;
+
+    case EXC_SOFTWARE:
+      *signo = SIGEMT;
+      *sigcode = code;
+      break;
+      
+    case EXC_BREAKPOINT:
+      *signo = SIGTRAP;
+      *sigcode = code;
+      break;
+    }
+}
diff --git a/sysdeps/mach/hurd/alpha/longjmp-ctx.c b/sysdeps/mach/hurd/alpha/longjmp-ctx.c
new file mode 100644
index 0000000000..dfc16fdfe4
--- /dev/null
+++ b/sysdeps/mach/hurd/alpha/longjmp-ctx.c
@@ -0,0 +1,38 @@
+/* Perform a `longjmp' on a `struct sigcontext'.  Alpha version.
+Copyright (C) 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <setjmp.h>
+#include <hurd/signal.h>
+#include <string.h>
+
+void
+_hurd_longjmp_sigcontext (struct sigcontext *scp, jmp_buf env, int retval)
+{
+  memset (scp, 0, sizeof (*scp));
+  scp->sc_regs[9] = env[0].__9;
+  scp->sc_regs[11] = env[0].__11;
+  scp->sc_regs[12] = env[0].__12;
+  scp->sc_regs[13] = env[0].__13;
+  scp->sc_regs[14] = env[0].__14;
+  scp->sc_regs[15] = (long int) env[0].__fp;
+  scp->sc_regs[30] = (long int) env[0].__sp;
+  scp->sc_pc = (long int) env[0].__pc;
+
+  memcpy (&scp->sc_fpregs[2], &env[0].__f2, sizeof (double));
+}
diff --git a/sysdeps/mach/hurd/alpha/longjmp-ts.c b/sysdeps/mach/hurd/alpha/longjmp-ts.c
new file mode 100644
index 0000000000..ad6f80cdb0
--- /dev/null
+++ b/sysdeps/mach/hurd/alpha/longjmp-ts.c
@@ -0,0 +1,41 @@
+/* Perform a `longjmp' on a Mach thread_state.  Alpha version.
+Copyright (C) 1991, 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <hurd/signal.h>
+#include <setjmp.h>
+#include <mach/thread_status.h>
+
+
+/* Set up STATE to do the equivalent of `longjmp (ENV, VAL);'.  */
+
+void
+_hurd_longjmp_thread_state (void *state, jmp_buf env, int val)
+{
+  struct alpha_thread_state *ts = state;
+
+  ts->r9 = env[0].__jmpbuf[0].__9;
+  ts->r11 = env[0].__jmpbuf[0].__11;
+  ts->r12 = env[0].__jmpbuf[0].__12;
+  ts->r13 = env[0].__jmpbuf[0].__13;
+  ts->r14 = env[0].__jmpbuf[0].__14;
+  ts->r15 = (long int) env[0].__jmpbuf[0].__fp;
+  ts->r30 = (long int) env[0].__jmpbuf[0].__sp;
+  ts->pc = (long int) env[0].__jmpbuf[0].__pc;
+  ts->r0 = val ?: 1;
+}
diff --git a/sysdeps/mach/hurd/alpha/sigcontext.h b/sysdeps/mach/hurd/alpha/sigcontext.h
new file mode 100644
index 0000000000..32e0c94f98
--- /dev/null
+++ b/sysdeps/mach/hurd/alpha/sigcontext.h
@@ -0,0 +1,65 @@
+/* Machine-dependent signal context structure for GNU Hurd.  Alpha version.
+Copyright (C) 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+/* Signal handlers are actually called:
+   void handler (int sig, int code, struct sigcontext *scp);  */
+
+/* State of this thread when the signal was taken.  */
+struct sigcontext
+  {
+    /* These first members are machine-independent.  */
+
+    long int sc_onstack;	/* Nonzero if running on sigstack.  */
+    __sigset_t sc_mask;		/* Blocked signals to restore.  */
+
+    /* MiG reply port this thread is using.  */
+    unsigned long int sc_reply_port;
+
+    /* Port this thread is doing an interruptible RPC on.  */
+    unsigned long int sc_intr_port;
+
+    /* Error code associated with this signal (interpreted as `error_t').  */
+    int sc_error;
+
+    /* All following members are machine-dependent.  The rest of this
+       structure is written to be laid out identically to:
+       {
+         struct alpha_thread_state basic;
+         struct alpha_exc_state exc;
+         struct alpha_float_state fpu;
+       }
+       trampoline.c knows this, so it must be changed if this changes.  */
+
+#define sc_alpha_thread_state sc_regs /* Beginning of correspondence.  */
+    long int sc_regs[31];	/* General registers $0..$30.  */
+    long int sc_pc;		/* Program counter.  */
+
+    /* struct alpha_exc_state */
+#define sc_alpha_exc_state sc_badvaddr
+    unsigned long int sc_badvaddr;
+    unsigned int sc_cause;	/* Machine-level trap code.  */
+#define SC_CAUSE_SET_SSTEP	1
+    int sc_used_fpa;		/* Nonzero if FPU was used.  */
+
+    /* struct alpha_float_state
+       This is only filled in if sc_used_fpa is nonzero.  */
+#define sc_alpha_float_state sc_fpregs
+    double sc_fpregs[31];	/* Floating point registers $f0..$f30.  */
+    long int sc_fpcsr;		/* Floating point control/status register.  */
+  };
diff --git a/sysdeps/mach/hurd/alpha/sigreturn.c b/sysdeps/mach/hurd/alpha/sigreturn.c
new file mode 100644
index 0000000000..e5dc383a3a
--- /dev/null
+++ b/sysdeps/mach/hurd/alpha/sigreturn.c
@@ -0,0 +1,212 @@
+/* Return from signal handler in GNU C library for Hurd.  Alpha version.
+Copyright (C) 1994, 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <hurd.h>
+#include <hurd/signal.h>
+#include <hurd/threadvar.h>
+#include <hurd/msg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <mach/machine/alpha_instruction.h>
+
+int
+__sigreturn (struct sigcontext *scp)
+{
+  struct hurd_sigstate *ss;
+  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);
+
+  /* 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;
+      /* Clear the intr_port slot, since we are not in fact doing
+	 an interruptible RPC right now.  If SS->intr_port is not null,
+	 the SCP context is doing an interruptible RPC, but the signal
+	 thread will examine us while we are blocked in the sig_post RPC.  */
+      ss->intr_port = MACH_PORT_NULL;
+      __spin_unlock (&ss->lock);
+      __msg_sig_post (_hurd_msgport, 0, __mach_task_self ());
+      /* If a pending signal was handled, sig_post never returned.  */
+      __spin_lock (&ss->lock);
+    }
+
+  if (scp->sc_onstack)
+    {
+      ss->sigaltstack.ss_flags &= ~SA_ONSTACK; /* XXX threadvars */
+      /* XXX cannot unlock until off sigstack */
+      abort ();
+    }
+  else
+    __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_destroy (__mach_task_self (), *reply_port);
+  *reply_port = scp->sc_reply_port;
+
+  if (scp->sc_used_fpa)
+    {
+      /* Restore FPU state.  */
+
+      /* Restore the floating-point control/status register.
+	 We must do this first because the compiler will need
+	 a temporary FP register for the load.  */
+      asm volatile ("mt_fpcr %0" : : "f" (scp->sc_fpcsr));
+
+      /* Restore floating-point registers. */
+#define restore_fpr(n) \
+  asm volatile ("ldt $f" #n ",%0" : : "m" (scp->sc_fpregs[n]))
+      restore_fpr (0);
+      restore_fpr (1);
+      restore_fpr (2);
+      restore_fpr (3);
+      restore_fpr (4);
+      restore_fpr (5);
+      restore_fpr (6);
+      restore_fpr (7);
+      restore_fpr (8);
+      restore_fpr (9);
+      restore_fpr (10);
+      restore_fpr (11);
+      restore_fpr (12);
+      restore_fpr (13);
+      restore_fpr (14);
+      restore_fpr (15);
+      restore_fpr (16);
+      restore_fpr (17);
+      restore_fpr (18);
+      restore_fpr (19);
+      restore_fpr (20);
+      restore_fpr (21);
+      restore_fpr (22);
+      restore_fpr (23);
+      restore_fpr (24);
+      restore_fpr (25);
+      restore_fpr (26);
+      restore_fpr (27);
+      restore_fpr (28);
+      restore_fpr (29);
+      restore_fpr (30);
+    }
+
+  /* Load all the registers from the sigcontext.  */
+#define restore_gpr(n) \
+  asm volatile ("ldq $" #n ",%0" : : "m" (scpreg->sc_regs[n]))
+
+  {
+    /* The `rei' PAL pseudo-instruction restores registers $2..$7, the PC
+       and processor status.  So we can use these few registers for our
+       working variables.  Unfortunately, it finds its data on the stack
+       and merely pops the SP ($30) over the words of state restored,
+       allowing no other option for the new SP value.  So we must push the
+       registers and PSW it will to restore, onto the user's stack and let
+       it pop them from there.  */
+    register const struct sigcontext *const scpreg asm ("$2") = scp;
+    register integer_t *usp asm ("$3") = (integer_t *) scpreg->sc_regs[30];
+    register integer_t usp_align asm ("$4");
+
+    /* Push an 8-word "trap frame" onto the user stack for `rei':
+       registers $2..$7, the PC, and the PSW.  */
+
+    register struct rei_frame
+      {
+	integer_t regs[5], pc, ps;
+      } *rei_frame asm ("$5");
+
+    usp -= 8;
+    /* `rei' demands that the stack be aligned to a 64 byte (8 word)
+       boundary; bits 61..56 of the PSW are OR'd back into the SP value
+       after popping the 8-word trap frame, so we store (sp % 64)
+       there and this restores the original user SP.  */
+    usp_align = (integer_t) usp & 63L;
+    rei_frame = (void *) ((integer_t) usp & ~63L);
+
+    /* Copy the registers and PC from the sigcontext.  */
+    memcpy (rei_frame->regs, &scpreg->sc_regs[2], sizeof rei_frame->regs);
+    rei_frame->pc = scpreg->sc_pc;
+
+    /* Compute the new PS value to be restored.  `rei' adds the value at
+       bits 61..56 to the SP to compensate for the alignment above that
+       cleared the low 6 bits; bits 5..3 are the new mode/privilege level
+       (must be >= current mode; 3 == user mode); bits 2..0 are "software",
+       unused by the processor or kernel (XXX should trampoline save these?
+       How?); in user mode, `rei' demands that all other bits be zero.  */
+    rei_frame->ps = (usp_align << 56) | (3 << 3); /* XXX low 3 bits??? */
+
+    /* Restore the other general registers: everything except $2..$7, which
+       are in the `rei' trap frame we set up above, and $30, which is the
+       SP which is popped by `rei'.  */
+    restore_gpr (1);
+    restore_gpr (8);
+    restore_gpr (9);
+    restore_gpr (10);
+    restore_gpr (11);
+    restore_gpr (12);
+    restore_gpr (13);
+    restore_gpr (14);
+    restore_gpr (15);
+    restore_gpr (16);
+    restore_gpr (17);
+    restore_gpr (18);
+    restore_gpr (19);
+    restore_gpr (20);
+    restore_gpr (21);
+    restore_gpr (22);
+    restore_gpr (23);
+    restore_gpr (24);
+    restore_gpr (25);
+    restore_gpr (26);
+    restore_gpr (27);
+    restore_gpr (28);
+    restore_gpr (29);
+
+    /* Switch the stack pointer to the trap frame set up on
+       the user stack and do the magical `rei' PAL call.  */
+    asm volatile ("mov %0, $30\n"
+		  "call_pal %1"
+		  : : "r" (rei_frame), "i" (op_rei));
+    /* Firewall.  */
+    asm volatile ("call_pal %0" : : "i" (op_halt));
+  }
+
+  /* NOTREACHED */
+  return -1;
+}
+
+weak_alias (__sigreturn, sigreturn)
diff --git a/sysdeps/mach/hurd/alpha/trampoline.c b/sysdeps/mach/hurd/alpha/trampoline.c
new file mode 100644
index 0000000000..85f4964e14
--- /dev/null
+++ b/sysdeps/mach/hurd/alpha/trampoline.c
@@ -0,0 +1,286 @@
+/* Set thread_state for sighandler, and sigcontext to recover.  Alpha version.
+Copyright (C) 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <hurd/signal.h>
+#include "thread_state.h"
+#include <mach/machine/alpha_instruction.h>
+#include "hurdfault.h"
+#include <assert.h>
+
+struct mach_msg_trap_args
+  {
+    /* This is the order of arguments to mach_msg_trap.  */
+    mach_msg_header_t *msg;
+    mach_msg_option_t option;
+    mach_msg_size_t send_size;
+    mach_msg_size_t rcv_size;
+    mach_port_t rcv_name;
+    mach_msg_timeout_t timeout;
+    mach_port_t notify;
+  };
+
+
+struct sigcontext *
+_hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
+			int signo, long int sigcode,
+			int rpc_wait,
+			struct machine_thread_all_state *state)
+{
+  __label__ trampoline, rpc_wait_trampoline;
+  void *sigsp;
+  struct sigcontext *scp;
+
+  if (ss->context)
+    {
+      /* We have a previous sigcontext that sigreturn was about
+	 to restore when another signal arrived.  We will just base
+	 our setup on that.  */
+      if (_hurdsig_catch_fault (SIGSEGV))
+	assert (_hurdsig_fault_sigcode >= (long int) ss->context &&
+		_hurdsig_fault_sigcode < (long int) (ss->context + 1));
+      else
+	{
+	  memcpy (&state->basic, &ss->context->sc_alpha_thread_state,
+		  sizeof (state->basic));
+	  memcpy (&state->exc, &ss->context->sc_alpha_exc_state,
+		  sizeof (state->exc));
+	  state->set = (1 << ALPHA_THREAD_STATE) | (1 << ALPHA_EXC_STATE);
+	  if (state->exc.used_fpa)
+	    {
+	      memcpy (&state->fpu, &ss->context->sc_alpha_float_state,
+		      sizeof (state->fpu));
+	      state->set |= (1 << ALPHA_FLOAT_STATE);
+	    }
+	  assert (! rpc_wait);
+	  /* The intr_port slot was cleared before sigreturn sent us the
+	     sig_post that made us notice this pending signal, so
+	     _hurd_internal_post_signal wouldn't do interrupt_operation.
+	     After we return, our caller will set SCP->sc_intr_port (in the
+	     new context) from SS->intr_port and clear SS->intr_port.  Now
+	     that we are restoring this old context recorded by sigreturn,
+	     we want to restore its intr_port too; so store it in
+	     SS->intr_port now, so it will end up in SCP->sc_intr_port
+	     later.  */
+	  ss->intr_port = ss->context->sc_intr_port;
+	}
+      /* If the sigreturn context was bogus, just ignore it.  */
+      ss->context = NULL;
+    }
+  else if (! machine_get_basic_state (ss->thread, state))
+    return NULL;
+
+  if ((ss->actions[signo].sa_flags & SA_ONSTACK) &&
+      !(ss->sigaltstack.ss_flags & (SA_DISABLE|SA_ONSTACK)))
+    {
+      sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size;
+      ss->sigaltstack.ss_flags |= SA_ONSTACK;
+      /* XXX need to set up base of new stack for
+	 per-thread variables, cthreads.  */
+    }
+  else
+    sigsp = (char *) state->basic.SP;
+
+  /* Set up the sigcontext structure on the stack.  This is all the stack
+     needs, since the args are passed in registers (below).  */
+  sigsp -= sizeof (*scp);
+  scp = sigsp;
+
+  if (_hurdsig_catch_fault (SIGSEGV))
+    {
+      assert (_hurdsig_fault_sigcode >= (long int) scp &&
+	      _hurdsig_fault_sigcode < (long int) (scp + 1));
+      /* We got a fault trying to write the stack frame.
+	 We cannot set up the signal handler.
+	 Returning NULL tells our caller, who will nuke us with a SIGILL.  */
+      return NULL;
+    }
+  else
+    {
+      /* Set up the sigcontext from the current state of the thread.  */
+
+      scp->sc_onstack = ss->sigaltstack.ss_flags & SA_ONSTACK ? 1 : 0;
+
+      /* struct sigcontext is laid out so that starting at sc_regs
+	 mimics a struct alpha_thread_state.  */
+      memcpy (&scp->sc_alpha_thread_state,
+	      &state->basic, sizeof (state->basic));
+
+      /* struct sigcontext is laid out so that starting at sc_badvaddr
+	 mimics a struct mips_exc_state.  */
+      if (! machine_get_state (ss->thread, state, ALPHA_EXC_STATE,
+			       &state->exc, &scp->sc_alpha_exc_state,
+			       sizeof (state->exc)))
+	return NULL;
+
+      if (state->exc.used_fpa &&
+	  /* struct sigcontext is laid out so that starting at sc_fpregs
+	     mimics a struct alpha_float_state.  This state
+	     is only meaningful if the coprocessor was used.  */
+	  ! machine_get_state (ss->thread, state, ALPHA_FLOAT_STATE,
+			       &state->fpu,
+			       &scp->sc_alpha_float_state,
+			       sizeof (state->fpu)))
+	return NULL;
+    }
+
+  /* Modify the thread state to call the trampoline code on the new stack.  */
+  if (rpc_wait)
+    {
+      /* The signalee thread was blocked in a mach_msg_trap system call,
+	 still waiting for a reply.  We will have it run the special
+	 trampoline code which retries the message receive before running
+	 the signal handler.
+	 
+	 To do this we change the OPTION argument in its registers to
+	 enable only message reception, since the request message has
+	 already been sent.  */
+
+      /* The system call arguments are stored in consecutive registers
+	 starting with a0 ($16).  */
+      struct mach_msg_trap_args *args = (void *) &state->basic.r16;
+
+      assert (args->option & MACH_RCV_MSG);
+      /* Disable the message-send, since it has already completed.  The
+	 calls we retry need only wait to receive the reply message.  */
+      args->option &= ~MACH_SEND_MSG;
+
+      state->basic.pc = (long int) &&rpc_wait_trampoline;
+      /* After doing the message receive, the trampoline code will need to
+	 update the v0 ($0) value to be restored by sigreturn.  To simplify
+	 the assembly code, we pass the address of its slot in SCP to the
+	 trampoline code in at ($28).  */
+      state->basic.r28 = (long int) &scp->sc_regs[0];
+      /* We must preserve the mach_msg_trap args in a0..a5 and t0
+	 ($16..$21, $1).  Pass the handler args to the trampoline code in
+	 t8..t10 ($22.$24).  */
+      state->basic.r22 = signo;
+      state->basic.r23 = sigcode;
+      state->basic.r24 = (long int) scp;
+    }
+  else
+    {
+      state->basic.pc = (long int) &&trampoline;
+      state->basic.r16 = signo;
+      state->basic.r17 = sigcode;
+      state->basic.r18 = (long int) scp;
+    }
+
+  state->basic.r30 = (long int) sigsp; /* $30 is the stack pointer.  */
+
+  /* We pass the handler function to the trampoline code in ra ($26).  */
+  state->basic.r26 = (long int) handler;
+  /* In the callee-saved register t12/pv ($27), we store the
+     address of __sigreturn itself, for the trampoline code to use.  */
+  state->basic.r27 = (long int) &__sigreturn;
+  /* In the callee-saved register t11/ai ($25), we save the SCP value to pass
+     to __sigreturn after the handler returns.  */
+  state->basic.r25 = (long int) scp;
+
+  return scp;
+
+  /* The trampoline code follows.  This is not actually executed as part of
+     this function, it is just convenient to write it that way.  */
+
+ rpc_wait_trampoline:
+  /* This is the entry point when we have an RPC reply message to receive
+     before running the handler.  The MACH_MSG_SEND bit has already been
+     cleared in the OPTION argument in our registers.  For our convenience,
+     at ($28) points to the sc_regs[0] member of the sigcontext (saved v0
+     ($0)).  */
+  asm volatile
+    (/* Retry the interrupted mach_msg system call.  */
+     "lda $0, -25($31)\n"	/* mach_msg_trap */
+     "call_pal %0\n"		/* Magic system call instruction.  */
+     /* When the sigcontext was saved, v0 was MACH_RCV_INTERRUPTED.  But
+	now the message receive has completed and the original caller of
+	the RPC (i.e. the code running when the signal arrived) needs to
+	see the final return value of the message receive in v0.  So
+	store the new v0 value into the sc_regs[0] member of the sigcontext
+	(whose address is in at to make this code simpler).  */
+     "stq $0, 0($28)\n"
+     /* Since the argument registers needed to have the mach_msg_trap
+	arguments, we've stored the arguments to the handler function
+	in registers t8..t10 ($22..$24).  */
+     "mov $22, $16\n"
+     "mov $23, $17\n"
+     "mov $24, $18\n"
+     : : "i" (op_chmk));
+
+ trampoline:
+  /* Entry point for running the handler normally.  The arguments to the
+     handler function are already in the standard registers:
+
+       a0	SIGNO
+       a1	SIGCODE
+       a2	SCP
+
+     t12 also contains SCP; this value is callee-saved (and so should not get
+     clobbered by running the handler).  We use this saved value to pass to
+     __sigreturn, so the handler can clobber the argument registers if it
+     likes.  */
+  /* Call the handler function, saving return address in ra ($26).  */
+  asm volatile ("jsr $26, ($26)");
+  /* Reset gp ($29) from the return address (here) in ra ($26).  */
+  asm volatile ("ldgp $29, 0($26)");
+  asm volatile ("mov $25, $16"); /* Move saved SCP to argument register.  */
+  /* Call __sigreturn (SCP); this cannot return.  */
+  asm volatile ("jmp $31, ($27)");
+
+  /* NOTREACHED */
+  return NULL;
+}
+
+/* STATE describes a thread that had intr_port set (meaning it was inside
+   HURD_EINTR_RPC), after it has been thread_abort'd.  If it looks to have
+   just completed a mach_msg_trap system call that returned
+   MACH_RCV_INTERRUPTED, return nonzero and set *PORT to the receive right
+   being waited on.  */
+int
+_hurdsig_rcv_interrupted_p (struct machine_thread_all_state *state,
+			    mach_port_t *port)
+{
+  if (state->basic.r0 == MACH_RCV_INTERRUPTED)
+    {
+      const unsigned int *pc = (void *) state->basic.pc;
+      struct mach_msg_trap_args *args = (void *) &state->basic.r16;
+
+      if (_hurdsig_catch_fault (SIGSEGV))
+	{
+	  assert (_hurdsig_fault_sigcode == (long int) (pc - 1) ||
+		  _hurdsig_fault_sigcode == (long int) &args->rcv_name);
+	  /* We got a fault trying to read the PC or stack.  */
+	  return 0;
+	}
+      else
+	{
+	  if (pc[-1] == ((alpha_instruction) { pal_format:
+						 { opcode: op_pal,
+						   function: op_chmk } }).bits)
+	    {
+	      /* We did just return from a mach_msg_trap system call
+		 doing a message receive that was interrupted.
+		 Examine the parameters to find the receive right.  */
+	      *port = args->rcv_name;
+	      return 1;
+	    }
+	}
+    }
+
+  return 0;
+}