1/* Signal trampoline unwinder, for GDB the GNU Debugger.
2
3   Copyright 2004 Free Software Foundation, Inc.
4
5   This file is part of GDB.
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 2 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program; if not, write to the Free Software
19   Foundation, Inc., 59 Temple Place - Suite 330,
20   Boston, MA 02111-1307, USA.  */
21
22#include "defs.h"
23#include "tramp-frame.h"
24#include "frame-unwind.h"
25#include "gdbcore.h"
26#include "symtab.h"
27#include "objfiles.h"
28#include "target.h"
29#include "trad-frame.h"
30#include "frame-base.h"
31#include "gdb_assert.h"
32
33struct frame_data
34{
35  const struct tramp_frame *tramp_frame;
36};
37
38struct tramp_frame_cache
39{
40  CORE_ADDR func;
41  const struct tramp_frame *tramp_frame;
42  struct trad_frame_cache *trad_cache;
43};
44
45static struct trad_frame_cache *
46tramp_frame_cache (struct frame_info *next_frame,
47		   void **this_cache)
48{
49  CORE_ADDR pc = frame_pc_unwind (next_frame);
50  struct tramp_frame_cache *tramp_cache = (*this_cache);
51  if (tramp_cache->trad_cache == NULL)
52    {
53      tramp_cache->trad_cache = trad_frame_cache_zalloc (next_frame);
54      tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
55				      next_frame,
56				      tramp_cache->trad_cache,
57				      tramp_cache->func);
58    }
59  return tramp_cache->trad_cache;
60}
61
62static void
63tramp_frame_this_id (struct frame_info *next_frame,
64		     void **this_cache,
65		     struct frame_id *this_id)
66{
67  struct trad_frame_cache *trad_cache
68    = tramp_frame_cache (next_frame, this_cache);
69  trad_frame_get_id (trad_cache, this_id);
70}
71
72static void
73tramp_frame_prev_register (struct frame_info *next_frame,
74			   void **this_cache,
75			   int prev_regnum,
76			   int *optimizedp,
77			   enum lval_type * lvalp,
78			   CORE_ADDR *addrp,
79			   int *realnump, void *valuep)
80{
81  struct trad_frame_cache *trad_cache
82    = tramp_frame_cache (next_frame, this_cache);
83  trad_frame_get_register (trad_cache, next_frame, prev_regnum, optimizedp,
84			   lvalp, addrp, realnump, valuep);
85}
86
87static CORE_ADDR
88tramp_frame_start (const struct tramp_frame *tramp,
89		   struct frame_info *next_frame, CORE_ADDR pc)
90{
91  int ti;
92  /* Search through the trampoline for one that matches the
93     instruction sequence around PC.  */
94  for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
95    {
96      CORE_ADDR func = pc - tramp->insn_size * ti;
97      int i;
98      for (i = 0; 1; i++)
99	{
100	  bfd_byte buf[sizeof (tramp->insn[0])];
101	  ULONGEST insn;
102	  if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
103	    return func;
104	  if (!safe_frame_unwind_memory (next_frame,
105					 func + i * tramp->insn_size,
106					 buf, tramp->insn_size))
107	    break;
108	  insn = extract_unsigned_integer (buf, tramp->insn_size);
109	  if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
110	    break;
111	}
112    }
113  /* Trampoline doesn't match.  */
114  return 0;
115}
116
117static int
118tramp_frame_sniffer (const struct frame_unwind *self,
119		     struct frame_info *next_frame,
120		     void **this_cache)
121{
122  const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
123  CORE_ADDR pc = frame_pc_unwind (next_frame);
124  CORE_ADDR func;
125  char *name;
126  struct tramp_frame_cache *tramp_cache;
127
128  /* If the function has a valid symbol name, it isn't a
129     trampoline.  */
130  find_pc_partial_function (pc, &name, NULL, NULL);
131  if (name != NULL)
132    return 0;
133  /* If the function lives in a valid section (even without a starting
134     point) it isn't a trampoline.  */
135  if (find_pc_section (pc) != NULL)
136    return 0;
137  /* Finally, check that the trampoline matches at PC.  */
138  func = tramp_frame_start (tramp, next_frame, pc);
139  if (func == 0)
140    return 0;
141  tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
142  tramp_cache->func = func;
143  tramp_cache->tramp_frame = tramp;
144  (*this_cache) = tramp_cache;
145  return 1;
146}
147
148void
149tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
150			      const struct tramp_frame *tramp_frame)
151{
152  struct frame_data *data;
153  struct frame_unwind *unwinder;
154  int i;
155
156  /* Check that the instruction sequence contains a sentinel.  */
157  for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
158    {
159      if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
160	break;
161    }
162  gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
163  gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
164
165  data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
166  unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
167
168  data->tramp_frame = tramp_frame;
169  unwinder->type = SIGTRAMP_FRAME;
170  unwinder->unwind_data = data;
171  unwinder->sniffer = tramp_frame_sniffer;
172  unwinder->this_id = tramp_frame_this_id;
173  unwinder->prev_register = tramp_frame_prev_register;
174  frame_unwind_prepend_unwinder (gdbarch, unwinder);
175}
176