src/fault-netbsd-alpha.c

   1 /* Fault handler information subroutine.  NetBSD/Alpha version.
   2  * Taken from gcc-3.3/boehm-gc/os_dep.c.
   3  *
   4  * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
   5  * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
   6  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
   7  * Copyright (c) 1999 by Hewlett-Packard Company.  All rights reserved.
   8  *
   9  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
  10  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
  11  *
  12  * Permission is hereby granted to use or copy this program
  13  * for any purpose,  provided the above notices are retained on all copies.
  14  * Permission to modify the code and to distribute modified code is granted,
  15  * provided the above notices are retained, and a notice that the code was
  16  * modified is included with the above copyright notice.
  17  */
  18
  19 /* Decodes the machine instruction which was responsible for the sending of the
  20    SIGBUS signal.  Luckily this is much easier than, say, on the PowerPC.  */
  21
  22 static void *
  23 get_fault_addr (struct sigcontext *scp)
  24 {
  25   unsigned int instr = *((unsigned int *)(scp->sc_pc));
  26   unsigned long faultaddr;
  27
  28   /* Instructions which access memory have operands of the form ARG_MEM or
  29      ARG_FMEM, consisting of
  30        - a base register specification (PRB) in bits 20..16,
  31        - a memory displacement (MDISP) in bits 15..0,
  32        - an general register specification (RA) or a floating-point register
  33          specification (FA) in bits 25..21.
  34      See binutils-2.13.90.0.16/opcodes/alpha-opc.c.  */
  35
  36   faultaddr = scp->sc_regs[(instr >> 16) & 0x1f];
  37   faultaddr += (unsigned long) (long) (((int)instr << 16) >> 16);
  38   return (void *) faultaddr;
  39 }