__label__ trampoline, rpc_wait_trampoline; void *sigsp;
__label__ trampoline, rpc_wait_trampoline, firewall; void *volatile sigsp;
_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;      /* Limit the time to receive the reply message, in case the server	 claimed that `interrupt_operation' succeeded but in fact the RPC	 is hung.  */      args->option |= MACH_RCV_TIMEOUT;      args->timeout = _hurd_interrupted_rpc_timeout;      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;}