1/* DWARF2 EH unwinding support for Alpha Linux.
2   Copyright (C) 2004-2015 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 3, or (at your option)
9any later version.
10
11GCC is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14GNU General Public License for more details.
15
16Under Section 7 of GPL version 3, you are granted additional
17permissions described in the GCC Runtime Library Exception, version
183.1, as published by the Free Software Foundation.
19
20You should have received a copy of the GNU General Public License and
21a copy of the GCC Runtime Library Exception along with this program;
22see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23<http://www.gnu.org/licenses/>.  */
24
25#ifndef inhibit_libc
26/* Do code reading to identify a signal frame, and set the frame
27   state data appropriately.  See unwind-dw2.c for the structs.  */
28
29#include <signal.h>
30#include <sys/ucontext.h>
31
32#define MD_FALLBACK_FRAME_STATE_FOR alpha_fallback_frame_state
33
34static _Unwind_Reason_Code
35alpha_fallback_frame_state (struct _Unwind_Context *context,
36			    _Unwind_FrameState *fs)
37{
38  unsigned int *pc = context->ra;
39  struct sigcontext *sc;
40  long new_cfa;
41  int i;
42
43  if (pc[0] != 0x47fe0410		/* mov $30,$16 */
44      || pc[2] != 0x00000083)		/* callsys */
45    return _URC_END_OF_STACK;
46  if (context->cfa == 0)
47    return _URC_END_OF_STACK;
48  if (pc[1] == 0x201f0067)		/* lda $0,NR_sigreturn */
49    sc = context->cfa;
50  else if (pc[1] == 0x201f015f)		/* lda $0,NR_rt_sigreturn */
51    {
52      struct rt_sigframe {
53	siginfo_t info;
54	struct ucontext uc;
55      } *rt_ = context->cfa;
56      sc = &rt_->uc.uc_mcontext;
57    }
58  else
59    return _URC_END_OF_STACK;
60
61  new_cfa = sc->sc_regs[30];
62  fs->regs.cfa_how = CFA_REG_OFFSET;
63  fs->regs.cfa_reg = 30;
64  fs->regs.cfa_offset = new_cfa - (long) context->cfa;
65  for (i = 0; i < 30; ++i)
66    {
67      fs->regs.reg[i].how = REG_SAVED_OFFSET;
68      fs->regs.reg[i].loc.offset
69	= (long) &sc->sc_regs[i] - new_cfa;
70    }
71  for (i = 0; i < 31; ++i)
72    {
73      fs->regs.reg[i+32].how = REG_SAVED_OFFSET;
74      fs->regs.reg[i+32].loc.offset
75	= (long) &sc->sc_fpregs[i] - new_cfa;
76    }
77  fs->regs.reg[64].how = REG_SAVED_OFFSET;
78  fs->regs.reg[64].loc.offset = (long)&sc->sc_pc - new_cfa;
79  fs->retaddr_column = 64;
80  fs->signal_frame = 1;
81
82  return _URC_NO_REASON;
83}
84
85#define MD_FROB_UPDATE_CONTEXT alpha_frob_update_context
86
87/* Fix up for signal handlers that don't have S flag set.  */
88
89static void
90alpha_frob_update_context (struct _Unwind_Context *context,
91			   _Unwind_FrameState *fs ATTRIBUTE_UNUSED)
92{
93  unsigned int *pc = context->ra;
94
95  if (pc[0] == 0x47fe0410		/* mov $30,$16 */
96      && pc[2] == 0x00000083		/* callsys */
97      && (pc[1] == 0x201f0067		/* lda $0,NR_sigreturn */
98	  || pc[1] == 0x201f015f))	/* lda $0,NR_rt_sigreturn */
99    _Unwind_SetSignalFrame (context, 1);
100}
101#endif
102