text: /*
   * Copyright (c) 2003 Marcel Moolenaar
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: src/lib/libc/amd64/gen/signalcontext.c,v 1.5 2004/07/28 13:08:24 davidxu Exp $");
  
  #include <sys/types.h>
  #include <sys/ucontext.h>
  #include <signal.h>
  #include <stdlib.h>
  #include <strings.h>
  
  typedef void (*handler_t)(uint64_t, uint64_t, uint64_t);
  
  /* Prototypes */
  static void sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args);
  
  __weak_reference(__signalcontext, signalcontext);
  
  int
  __signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
  {
  	uint64_t *args;
  	siginfo_t *sig_si;
  	ucontext_t *sig_uc;
  	uint64_t sp;
  
  	/* Bail out if we don't have a valid ucontext pointer. */
  	if (ucp == NULL)
  		abort();
  
  	/*
  	 * Build a signal frame and copy the arguments of signal handler
  	 * 'func' onto the stack and do the funky stack alignment.
  	 * This means that we need an 8-byte-odd alignment since the ABI expects
  	 * the return address to be pushed, thus breaking the 16 byte alignment.
  	 */
  	sp = (ucp->uc_mcontext.mc_rsp - 128 - sizeof(ucontext_t)) & ~15UL;
  	sig_uc = (ucontext_t *)sp;
  	bcopy(ucp, sig_uc, sizeof(*sig_uc));
  	sp = (sp - sizeof(siginfo_t)) & ~15UL;
  	sig_si = (siginfo_t *)sp;
  	bzero(sig_si, sizeof(*sig_si));
  	sig_si->si_signo = sig;
  	sp -= 3 * sizeof(uint64_t);
  	args = (uint64_t *)sp;
  	args[0] = sig;
  	args[1] = (intptr_t)sig_si;
  	args[2] = (intptr_t)sig_uc;
  	sp -= 16;
  
  	/*
  	 * Setup the ucontext of the signal handler.
  	 */
  	bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext));
  	ucp->uc_mcontext.mc_fpformat = _MC_FPFMT_NODEV;
  	ucp->uc_mcontext.mc_ownedfp = _MC_FPOWNED_NONE;
  	ucp->uc_link = sig_uc;
  	sigdelset(&ucp->uc_sigmask, sig);
  
  	ucp->uc_mcontext.mc_len = sizeof(mcontext_t);
  	ucp->uc_mcontext.mc_rdi = (register_t)ucp;
  	ucp->uc_mcontext.mc_rsi = (register_t)func;
  	ucp->uc_mcontext.mc_rdx = (register_t)args;
  	ucp->uc_mcontext.mc_rbp = (register_t)sp;
  	ucp->uc_mcontext.mc_rbx = (register_t)sp;
  	ucp->uc_mcontext.mc_rsp = (register_t)sp;
  	ucp->uc_mcontext.mc_rip = (register_t)sigctx_wrapper;
  	return (0);
  }
  
  static void
  sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args)
  {
  
  	(*func)(args[0], args[1], args[2]);
  	if (ucp->uc_link == NULL)
  		exit(0);
  	setcontext((const ucontext_t *)ucp->uc_link);
  	/* should never get here */
  	abort();
  	/* NOTREACHED */
  }
  