initial import

1 files changed, 271 insertions, 0 deletions

diff --git a/sysdeps/mach/hurd/i386/trampoline.c b/sysdeps/mach/hurd/i386/trampoline.c
new file mode 100644
index 0000000000..eabf940b44
--- /dev/null
+++ b/sysdeps/mach/hurd/i386/trampoline.c
@@ -0,0 +1,271 @@
+/* Set thread_state for sighandler, and sigcontext to recover.  i386 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 <assert.h>
+#include <errno.h>
+#include "hurdfault.h"
+
+     
+struct mach_msg_trap_args
+  {
+    void *retaddr;		/* Address mach_msg_trap will return to.  */
+    /* 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,
+			volatile int rpc_wait,
+			struct machine_thread_all_state *state)
+{
+  __label__ trampoline, rpc_wait_trampoline;
+  void *volatile sigsp;
+  struct sigcontext *scp;
+  struct 
+    {
+      int signo;
+      long int sigcode;
+      struct sigcontext *scp;	/* Points to ctx, below.  */
+      struct sigcontext *return_scp; /* Same; arg to sigreturn.  */
+      struct sigcontext ctx;
+    } *stackframe;
+
+  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_i386_thread_state,
+		  sizeof (state->basic));
+	  memcpy (&state->fpu, &ss->context->sc_i386_float_state,
+		  sizeof (state->fpu));
+	  state->set = (1 << i386_THREAD_STATE) | (1 << i386_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.uesp;
+
+  /* Push the arguments to call `trampoline' on the stack.  */
+  sigsp -= sizeof (*stackframe);
+  stackframe = sigsp;
+
+  if (_hurdsig_catch_fault (SIGSEGV))
+    {
+      assert (_hurdsig_fault_sigcode >= (long int) stackframe &&
+	      _hurdsig_fault_sigcode <= (long int) (stackframe + 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
+    {
+      int ok;
+
+      /* Set up the arguments for the signal handler.  */
+      stackframe->signo = signo;
+      stackframe->sigcode = sigcode;
+      stackframe->scp = stackframe->return_scp = scp = &stackframe->ctx;
+
+      /* 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_gs mimics a
+	 struct i386_thread_state.  */
+      memcpy (&scp->sc_i386_thread_state,
+	      &state->basic, sizeof (state->basic));
+
+      /* struct sigcontext is laid out so that starting at sc_fpkind mimics
+	 a struct i386_float_state.  */
+      ok = machine_get_state (ss->thread, state, i386_FLOAT_STATE,
+			      &state->fpu, &scp->sc_i386_float_state,
+			      sizeof (state->fpu));
+
+      _hurdsig_end_catch_fault ();
+
+      if (! ok)
+	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 on its stack to enable only
+	 message reception, since the request message has already been
+	 sent.  */
+
+      struct mach_msg_trap_args *args = (void *) state->basic.uesp;
+
+      if (_hurdsig_catch_fault (SIGSEGV))
+	{
+	  assert (_hurdsig_fault_sigcode >= (long int) args &&
+		  _hurdsig_fault_sigcode < (long int) (args + 1));
+	  /* Faulted accessing ARGS.  Bomb.  */
+	  return NULL;
+	}
+
+      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;
+
+      _hurdsig_end_catch_fault ();
+
+      state->basic.eip = (int) &&rpc_wait_trampoline;
+      /* The reply-receiving trampoline code runs initially on the original
+	 user stack.  We pass it the signal stack pointer in %ebx.  */
+      state->basic.ebx = (int) sigsp;
+      /* After doing the message receive, the trampoline code will need to
+	 update the %eax 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 %ecx.  */
+      state->basic.ecx = (int) &scp->sc_eax;
+    }
+  else
+    {
+      state->basic.eip = (int) &&trampoline;
+      state->basic.uesp = (int) sigsp;
+    }
+  /* We pass the handler function to the trampoline code in %edx.  */
+  state->basic.edx = (int) handler;
+
+  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 on our stack.  The interrupted user
+     stack pointer has not been changed, so the system call can find its
+     arguments; the signal stack pointer is in %ebx.  For our convenience,
+     %ecx points to the sc_eax member of the sigcontext.  */
+  asm volatile
+    (/* Retry the interrupted mach_msg system call.  */
+     "movl $-25, %eax\n"	/* mach_msg_trap */
+     "lcall $7, $0\n"
+     /* When the sigcontext was saved, %eax 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 %eax.  So
+	store the new %eax value into the sc_eax member of the sigcontext
+	(whose address is in %ecx to make this code simpler).  */
+     "movl %eax, (%ecx)\n"
+     /* Switch to the signal stack.  */
+     "movl %ebx, %esp\n");
+
+ trampoline:
+  /* Entry point for running the handler normally.  The arguments to the
+     handler function are already on the top of the stack:
+
+       0(%esp)	SIGNO
+       4(%esp)	SIGCODE
+       8(%esp)	SCP
+     */
+  asm volatile
+    ("call %*%%edx\n"		/* Call the handler function.  */
+     "addl $12, %%esp\n"	/* Pop its args.  */
+     "call %P0\n"		/* Call __sigreturn (SCP); never returns.  */
+     "hlt"			/* Just in case.  */
+     : : "i" (&__sigreturn));
+
+  /* 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.  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)
+{
+  static const unsigned char syscall[] = { 0x9a, 0, 0, 0, 0, 7, 0 };
+  const unsigned char *volatile pc
+    = (void *) state->basic.eip - sizeof syscall;
+
+  if (_hurdsig_catch_fault (SIGSEGV))
+    assert (_hurdsig_fault_sigcode >= (long int) pc &&
+	    _hurdsig_fault_sigcode < (long int) pc + sizeof syscall);
+  else
+    {
+      int rcving = (state->basic.eax == MACH_RCV_INTERRUPTED &&
+		    !memcmp (pc, &syscall, sizeof syscall));
+      _hurdsig_end_catch_fault ();
+      if (rcving)
+	{
+	  /* 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.uesp;
+
+	  *port = args->rcv_name;
+	  return 1;
+	}
+    }
+
+  return 0;
+}