initial import

7 files changed, 725 insertions, 0 deletions

diff --git a/sysdeps/mach/hurd/mips/exc2signal.c b/sysdeps/mach/hurd/mips/exc2signal.c
new file mode 100644
index 0000000000..f907c89cf0
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/exc2signal.c
@@ -0,0 +1,98 @@
+/* Translate Mach exception codes into signal numbers.  MIPS version.
+Copyright (C) 1991, 1992, 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 <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;
+      if (code == EXC_MIPS_II)
+	*sigcode = code;
+      else
+	*sigcode = 0;
+      break;
+      
+    case EXC_ARITHMETIC:
+      switch (code)
+	{
+	case EXC_MIPS_OV:	/* integer overflow */
+	  *signo = SIGFPE;
+	  *sigcode = EXC_MIPS_FLT_OVERFLOW;
+	  break;
+
+	default:
+	  *signo = SIGFPE;
+	  *sigcode = 0;
+	  break;
+
+	case EXC_MIPS_INT:
+	  /* Subcode is the fp_status word saved by the hardware.
+	     Give an error code corresponding to the first bit set.  */
+	  if (subcode == EXC_MIPS_FLT_UNIMP)
+	    *signo = SIGILL;
+	  else
+	    *signo = SIGFPE;
+	  *sigcode = subcode;
+	  break;
+	}
+      break;
+
+    case EXC_EMULATION:		
+      /* 3.0 doesn't give this one, why, I don't know.  */
+      *signo = SIGEMT;
+      *sigcode = 0;
+      break;
+
+    case EXC_SOFTWARE:
+      *signo = SIGEMT;
+      *sigcode = 0;
+      break;
+      
+    case EXC_BREAKPOINT:
+      *signo = SIGTRAP;
+      *sigcode = code;
+      break;
+    }
+}
diff --git a/sysdeps/mach/hurd/mips/init-fault.c b/sysdeps/mach/hurd/mips/init-fault.c
new file mode 100644
index 0000000000..e6f8acf64d
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/init-fault.c
@@ -0,0 +1,41 @@
+/* Set up a thread_state for proc_handle_exceptions.  MIPS 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 <mach/thread_status.h>
+#include <string.h>
+#include <setjmp.h>
+
+extern jmp_buf _hurd_sigthread_fault_env;
+
+static char fault_stack[32];
+static volatile void
+faulted (void)
+{
+  __longjmp (_hurd_sigthread_fault_env, 1);
+}
+
+void
+_hurd_initialize_fault_recovery_state (void *state)
+{
+  struct mips_thread_state *ts = state;
+  memset (ts, 0, sizeof (*ts));
+  ts->r29 = (int) &fault_stack[sizeof (fault_stack)];
+  ts->pc = (int) &faulted;
+}
diff --git a/sysdeps/mach/hurd/mips/longjmp-ctx.c b/sysdeps/mach/hurd/mips/longjmp-ctx.c
new file mode 100644
index 0000000000..0c78f6b4d6
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/longjmp-ctx.c
@@ -0,0 +1,41 @@
+/* Perform a `longjmp' on a `struct sigcontext'.  MIPS 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)
+{
+  scp->sc_gpr[16] = env[0].__regs[0];
+  scp->sc_gpr[17] = env[0].__regs[1];
+  scp->sc_gpr[18] = env[0].__regs[2];
+  scp->sc_gpr[19] = env[0].__regs[3];
+  scp->sc_gpr[20] = env[0].__regs[4];
+  scp->sc_gpr[21] = env[0].__regs[5];
+  scp->sc_gpr[22] = env[0].__regs[6];
+  scp->sc_gpr[23] = env[0].__regs[7];
+
+  scp->sc_gpr[28] = (int) env[0].__gp;
+  scp->sc_fp = (int) env[0].__fp;
+  scp->sc_sp = (int) env[0].__sp;
+  scp->sc_pc = (int) env[0].__pc;
+  scp->sc_gpr[2] = retval ?: 1;
+}
diff --git a/sysdeps/mach/hurd/mips/longjmp-ts.c b/sysdeps/mach/hurd/mips/longjmp-ts.c
new file mode 100644
index 0000000000..980a2ceb94
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/longjmp-ts.c
@@ -0,0 +1,45 @@
+/* Perform a `longjmp' on a Mach thread_state.  MIPS 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 mips_thread_state *ts = state;
+
+  ts->r16 = env[0].__jmpbuf[0].__regs[0];
+  ts->r17 = env[0].__jmpbuf[0].__regs[1];
+  ts->r18 = env[0].__jmpbuf[0].__regs[2];
+  ts->r19 = env[0].__jmpbuf[0].__regs[3];
+  ts->r20 = env[0].__jmpbuf[0].__regs[4];
+  ts->r21 = env[0].__jmpbuf[0].__regs[5];
+  ts->r22 = env[0].__jmpbuf[0].__regs[6];
+  ts->r23 = env[0].__jmpbuf[0].__regs[7];
+  ts->r28 = (int) env[0].__jmpbuf[0].__gp;
+  ts->r29 = (int) env[0].__jmpbuf[0].__sp;
+  ts->r30 = (int) env[0].__jmpbuf[0].__fp;
+  ts->pc = (int) env[0].__jmpbuf[0].__pc;
+  ts->r2 = val ?: 1;
+}
diff --git a/sysdeps/mach/hurd/mips/sigcontext.h b/sysdeps/mach/hurd/mips/sigcontext.h
new file mode 100644
index 0000000000..81d1f25f25
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/sigcontext.h
@@ -0,0 +1,71 @@
+/* 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.  */
+
+    int sc_onstack;		/* Nonzero if running on sigstack.  */
+    __sigset_t sc_mask;		/* Blocked signals to restore.  */
+
+    /* MiG reply port this thread is using.  */
+    unsigned int sc_reply_port;
+
+    /* Port this thread is doing an interruptible RPC on.  */
+    unsigned 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 mips_thread_state ts;
+	  struct mips_exc_state es;
+	  struct mips_float_state fs;
+	}
+       trampoline.c knows this, so it must be changed if this changes.  */
+#define	sc_mips_thread_state sc_gpr /* Beginning of correspondence.  */
+    int sc_gpr[31];		/* "General" registers; [0] is r1.  */
+    int sc_mdlo, sc_mdhi;	/* Low and high multiplication results.  */
+    int sc_pc;			/* Instruction pointer.  */
+
+    /* struct mips_exc_state */
+#define sc_mips_exc_state sc_cause
+    unsigned int sc_cause;	/* Machine-level trap code.  */
+#define SC_CAUSE_SST	0x00000044
+    unsigned int sc_badvaddr;
+    unsigned int sc_coproc_used; /* Which coprocessors the thread has used.  */
+#define SC_COPROC_USE_COP0	1 /* (by definition) */
+#define SC_COPROC_USE_COP1	2 /* FPA */
+#define	SC_COPROC_USE_FPU	SC_COPROC_USE_COP1
+#define SC_COPROC_USE_COP2	4
+#define SC_COPROC_USE_COP3	8
+
+    /* struct mips_float_state
+       This is only filled in if the SC_COPROC_USE_FPU bit
+       is set in sc_coproc_used.  */
+#define sc_mips_float_state sc_fpr
+    int sc_fpr[32];		/* FP registers.  */
+    int sc_fpcsr;		/* FPU status register.  */
+    int sc_fpeir;		/* FP exception instruction register.  */
+  };
diff --git a/sysdeps/mach/hurd/mips/sigreturn.c b/sysdeps/mach/hurd/mips/sigreturn.c
new file mode 100644
index 0000000000..7396a8bb22
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/sigreturn.c
@@ -0,0 +1,169 @@
+/* Copyright (C) 1991, 1992, 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 <stdlib.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_coproc_used & SC_COPROC_USE_FPU)
+    {
+      /* Restore FPU state.  */
+#define restore_fpr(n) \
+  asm volatile ("l.d $f" #n ",%0" : : "m" (scp->sc_fpr[n]))
+
+      /* Restore floating-point registers. */
+      restore_fpr (0);
+      restore_fpr (2);
+      restore_fpr (4);
+      restore_fpr (6);
+      restore_fpr (8);
+      restore_fpr (10);
+      restore_fpr (12);
+      restore_fpr (14);
+      restore_fpr (16);
+      restore_fpr (18);
+      restore_fpr (20);
+      restore_fpr (22);
+      restore_fpr (24);
+      restore_fpr (26);
+      restore_fpr (28);
+      restore_fpr (30);
+
+      /* Restore the floating-point control/status register ($f31).  */
+      asm volatile ("ctc1 %0,$f31" : : "r" (scp->sc_fpcsr));
+    }
+
+  /* Load all the registers from the sigcontext.  */
+#define restore_gpr(n) \
+  asm volatile ("lw $" #n ",%0" : : "m" (scpreg->sc_gpr[n - 1]))
+
+  {
+    register const struct sigcontext *const scpreg asm ("$1") = scp;
+    register int *at asm ("$1");
+
+    /* First restore the multiplication result registers.  The compiler
+       will use some temporary registers, so we do this before restoring
+       the general registers.  */
+    asm volatile ("mtlo %0" : : "r" (scpreg->sc_mdlo));
+    asm volatile ("mthi %0" : : "r" (scpreg->sc_mdhi));
+
+    /* In the word after the saved PC, store the saved $1 value.  */
+    (&scpreg->sc_pc)[1] = scpreg->sc_gpr[0];
+
+    asm volatile (".set noreorder; .set noat;");
+
+    /* Restore the normal registers.  */
+    restore_gpr (2);
+    restore_gpr (3);
+    restore_gpr (4);
+    restore_gpr (5);
+    restore_gpr (6);
+    restore_gpr (7);
+    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);
+    /* Registers 26-27 are kernel-only.  */
+    restore_gpr (28);
+    restore_gpr (29);		/* Stack pointer.  */
+    restore_gpr (30);		/* Frame pointer.  */
+    restore_gpr (31);		/* Return address.  */
+
+    at = &scpreg->sc_pc;
+    /* This is an emulated instruction that will find at the address in $1
+       two words: the PC value to restore, and the $1 value to restore.  */
+    asm volatile (".word op_sigreturn");
+
+    asm volatile (".set reorder; .set at;");
+  }
+
+  /* NOTREACHED */
+  return -1;
+}
+
+weak_alias (__sigreturn, sigreturn)
diff --git a/sysdeps/mach/hurd/mips/trampoline.c b/sysdeps/mach/hurd/mips/trampoline.c
new file mode 100644
index 0000000000..f03ad5852f
--- /dev/null
+++ b/sysdeps/mach/hurd/mips/trampoline.c
@@ -0,0 +1,260 @@
+/* Set thread_state for sighandler, and sigcontext to recover.  MIPS 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/signal.h>
+#include "thread_state.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 (! setjmp (_hurd_sigthread_fault_env))
+	{
+	  memcpy (&state->basic, &ss->context->sc_mips_thread_state,
+		  sizeof (state->basic));
+	  memcpy (&state->exc, &ss->context->sc_mips_exc_state,
+		  sizeof (state->exc));
+	  state->set = (1 << MIPS_THREAD_STATE) | (1 << MIPS_EXC_STATE);
+	  if (state->exc.coproc_state & SC_COPROC_USE_FPU)
+	    {
+	      memcpy (&state->fpu, &ss->context->sc_mips_float_state,
+		      sizeof (state->fpu));
+	      state->set |= (1 << MIPS_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.r29;
+
+  /* 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 (! setjmp (_hurd_sigthread_fault_env))
+    {
+      /* 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_gpr
+	 mimics a struct mips_thread_state.  */
+      memcpy (&scp->sc_mips_thread_state,
+	      &state->basic, sizeof (state->basic));
+
+      /* struct sigcontext is laid out so that starting at sc_cause
+	 mimics a struct mips_exc_state.  */
+      if (! machine_get_state (ss->thread, state, MIPS_EXC_STATE,
+			       &state->exc, &scp->sc_cause,
+			       sizeof (state->exc)))
+	return NULL;
+      if ((scp->sc_coproc_used & SC_COPROC_USE_FPU) &&
+	  /* struct sigcontext is laid out so that starting at sc_fpr
+	     mimics a struct mips_float_state.  This state
+	     is only meaningful if the coprocessor was used.  */
+	  ! machine_get_state (ss->thread, state, MIPS_FLOAT_STATE,
+			       &state->fpu,
+			       &scp->sc_mips_float_state, sizeof (state->fpu)))
+	return NULL;
+    }
+  else
+    /* 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;
+
+  /* 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 ($4).  */
+      struct mach_msg_trap_args *args = (void *) &state->basic.r4;
+
+      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 = (int) &&rpc_wait_trampoline;
+      state->basic.r29 = (int) sigsp; /* $29 is the stack pointer register.  */
+      /* After doing the message receive, the trampoline code will need to
+	 update the v0 ($2) 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 v1 ($3).  */
+      state->basic.r3 = (int) &scp->sc_gpr[1];
+      /* We must preserve the mach_msg_trap args in a0..t2 ($4..$10).
+	 Pass the handler args to the trampoline code in s1..s3 ($17..$19).  */
+      state->basic.r17 = signo;
+      state->basic.r18 = sigcode;
+      state->basic.r19 = (int) scp;
+    }
+  else
+    {
+      state->basic.pc = (int) &&trampoline;
+      state->basic.r29 = (int) sigsp;
+      state->basic.r4 = signo;
+      state->basic.r5 = sigcode;
+      state->basic.r6 = (int) scp;
+    }
+
+  /* We pass the handler function to the trampoline code in at ($1).  */
+  state->basic.r1 = (int) handler;
+  /* In the callee-saved register s0 ($16), we save the SCP value to pass
+     to __sigreturn after the handler returns.  */
+  state->basic.r16 = (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,
+     $3 points to the sc_gpr[1] member of the sigcontext (saved v0 ($2)).  */
+  asm volatile
+    (".set noat; .set noreorder; .set nomacro\n"
+     /* Retry the interrupted mach_msg system call.  */
+     "li $2, -25\n"		/* mach_msg_trap */
+     "syscall\n"
+     /* 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_gpr[1] member of the sigcontext
+	(whose address is in v1 to make this code simpler).  */
+     "sw $2, ($3)\n"
+     /* Since the argument registers needed to have the mach_msg_trap
+	arguments, we've stored the arguments to the handler function
+	in registers s1..s3 ($17..$19).  */
+     "move $4, $17\n"
+     "move $5, $18\n"
+     "move $6, $19\n");
+
+ 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
+     */
+  asm volatile
+    ("jal $1; nop\n"		/* Call the handler function.  */
+     /* Call __sigreturn (SCP); this cannot return.  */
+     "j %0\n"
+     "move $4, $16"		/* Set up arg from saved SCP in delay slot.  */
+     : : "i" (&__sigreturn));
+
+  /* NOTREACHED */
+  asm volatile (".set reorder; .set at; .set macro");
+
+  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.  It 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)
+{
+  const unsigned int *const pc = (void *) state->basic.pc;
+
+  if (_hurdsig_catch_fault (SIGSEGV))
+    assert (_hurdsig_fault_sigcode == (long int) pc);
+  else
+    {
+      if (state->basic.r2 == MACH_RCV_INTERRUPTED &&
+	  pc[-1] == 0xc)	/* syscall */
+	{
+	  /* 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.  */
+	  struct mach_msg_trap_args *args = (void *) &state->basic.r4;
+
+	  *port = args->rcv_name;
+	  return 1;
+	}
+    }
+
+  return 0;
+}