gdb/i386bsd-tdep.c

   1 /* Target-dependent code for i386 BSD's.
   2    Copyright 2001 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include "defs.h"
  22 #include "frame.h"
  23 #include "gdbcore.h"
  24 #include "regcache.h"
  25
  26 /* Support for signal handlers.  */
  27
  28 /* Range in which to find the signaltramp routine, traditionally found
  29    on the use stack, just below the user area.  Initialized to values
  30    that work for NetBSD and FreeBSD.  */
  31
  32 CORE_ADDR i386bsd_sigtramp_start = 0xbfbfdf20;
  33 CORE_ADDR i386bsd_sigtramp_end = 0xbfbfdff0;
  34
  35 /* Return whether PC is in a BSD sigtramp routine.  */
  36
  37 int
  38 i386bsd_in_sigtramp (CORE_ADDR pc, char *name)
  39 {
  40   return (pc >= i386bsd_sigtramp_start && pc < i386bsd_sigtramp_end);
  41 }
  42
  43 /* Offset in the sigcontext structure of the program counter.
  44    Initialized to the value from 4.4 BSD Lite.  */
  45 int i386bsd_sigcontext_pc_offset = 20;
  46
  47 /* Assuming FRAME is for a BSD sigtramp routine, return the address of
  48    the associated sigcontext structure.  */
  49
  50 static CORE_ADDR
  51 i386bsd_sigcontext_addr (struct frame_info *frame)
  52 {
  53   if (frame->next)
  54     /* If this isn't the top frame, the next frame must be for the
  55        signal handler itself.  A pointer to the sigcontext structure
  56        is passed as the third argument to the signal handler.  */
  57     return read_memory_unsigned_integer (frame->next->frame + 16, 4);
  58
  59   /* This is the top frame.  We'll have to find the address of the
  60      sigcontext structure by looking at the stack pointer.  */
  61   return read_memory_unsigned_integer (read_register (SP_REGNUM) + 8, 4);
  62 }
  63
  64 /* Assuming FRAME is for a BSD sigtramp routine, return the saved
  65    program counter.  */
  66
  67 static CORE_ADDR
  68 i386bsd_sigtramp_saved_pc (struct frame_info *frame)
  69 {
  70   CORE_ADDR addr;
  71   addr = i386bsd_sigcontext_addr (frame);
  72   return read_memory_unsigned_integer (addr + i386bsd_sigcontext_pc_offset, 4);
  73 }
  74
  75 /* Return the saved program counter for FRAME.  */
  76
  77 CORE_ADDR
  78 i386bsd_frame_saved_pc (struct frame_info *frame)
  79 {
  80   if (frame->signal_handler_caller)
  81     return i386bsd_sigtramp_saved_pc (frame);
  82
  83   return read_memory_unsigned_integer (frame->frame + 4, 4);
  84 }