1 files changed, 286 insertions, 0 deletions
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;
+}