1/* DWARF2 EH unwinding support for Alpha Linux.
2   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 2, or (at your option)
9any later version.
10
11In addition to the permissions in the GNU General Public License, the
12Free Software Foundation gives you unlimited permission to link the
13compiled version of this file with other programs, and to distribute
14those programs without any restriction coming from the use of this
15file.  (The General Public License restrictions do apply in other
16respects; for example, they cover modification of the file, and
17distribution when not linked into another program.)
18
19GCC is distributed in the hope that it will be useful,
20but WITHOUT ANY WARRANTY; without even the implied warranty of
21MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22GNU General Public License for more details.
23
24You should have received a copy of the GNU General Public License
25along with GCC; see the file COPYING.  If not, write to
26the Free Software Foundation, 51 Franklin Street, Fifth Floor,
27Boston, MA 02110-1301, USA.  */
28
29/* Do code reading to identify a signal frame, and set the frame
30   state data appropriately.  See unwind-dw2.c for the structs.  */
31
32#include <signal.h>
33#include <sys/ucontext.h>
34
35#define MD_FALLBACK_FRAME_STATE_FOR alpha_fallback_frame_state
36
37static _Unwind_Reason_Code
38alpha_fallback_frame_state (struct _Unwind_Context *context,
39			    _Unwind_FrameState *fs)
40{
41  unsigned int *pc = context->ra;
42  struct sigcontext *sc;
43  long new_cfa, i;
44
45  if (pc[0] != 0x47fe0410		/* mov $30,$16 */
46      || pc[2] != 0x00000083		/* callsys */)
47    return _URC_END_OF_STACK;
48  if (context->cfa == 0)
49    return _URC_END_OF_STACK;
50  if (pc[1] == 0x201f0067)		/* lda $0,NR_sigreturn */
51    sc = context->cfa;
52  else if (pc[1] == 0x201f015f)	/* lda $0,NR_rt_sigreturn */
53    {
54      struct rt_sigframe {
55	struct siginfo info;
56	struct ucontext uc;
57      } *rt_ = context->cfa;
58      sc = &rt_->uc.uc_mcontext;
59    }
60  else
61    return _URC_END_OF_STACK;
62  new_cfa = sc->sc_regs[30];
63  fs->cfa_how = CFA_REG_OFFSET;
64  fs->cfa_reg = 30;
65  fs->cfa_offset = new_cfa - (long) context->cfa;
66  for (i = 0; i < 30; ++i)
67    {
68      fs->regs.reg[i].how = REG_SAVED_OFFSET;
69      fs->regs.reg[i].loc.offset
70	= (long)&sc->sc_regs[i] - new_cfa;
71    }
72  for (i = 0; i < 31; ++i)
73    {
74      fs->regs.reg[i+32].how = REG_SAVED_OFFSET;
75      fs->regs.reg[i+32].loc.offset
76	= (long)&sc->sc_fpregs[i] - new_cfa;
77    }
78  fs->regs.reg[64].how = REG_SAVED_OFFSET;
79  fs->regs.reg[64].loc.offset = (long)&sc->sc_pc - new_cfa;
80  fs->retaddr_column = 64;
81  return _URC_NO_REASON;
82}
83