1/* Signal trampoline unwinder, for GDB the GNU Debugger.
2
3   Copyright (C) 2004, 2007 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 3 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, see <http://www.gnu.org/licenses/>.  */
19
20#include "defs.h"
21#include "tramp-frame.h"
22#include "frame-unwind.h"
23#include "gdbcore.h"
24#include "symtab.h"
25#include "objfiles.h"
26#include "target.h"
27#include "trad-frame.h"
28#include "frame-base.h"
29#include "gdb_assert.h"
30
31struct frame_data
32{
33  const struct tramp_frame *tramp_frame;
34};
35
36struct tramp_frame_cache
37{
38  CORE_ADDR func;
39  const struct tramp_frame *tramp_frame;
40  struct trad_frame_cache *trad_cache;
41};
42
43static struct trad_frame_cache *
44tramp_frame_cache (struct frame_info *next_frame,
45		   void **this_cache)
46{
47  CORE_ADDR pc = frame_pc_unwind (next_frame);
48  struct tramp_frame_cache *tramp_cache = (*this_cache);
49  if (tramp_cache->trad_cache == NULL)
50    {
51      tramp_cache->trad_cache = trad_frame_cache_zalloc (next_frame);
52      tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
53				      next_frame,
54				      tramp_cache->trad_cache,
55				      tramp_cache->func);
56    }
57  return tramp_cache->trad_cache;
58}
59
60static void
61tramp_frame_this_id (struct frame_info *next_frame,
62		     void **this_cache,
63		     struct frame_id *this_id)
64{
65  struct trad_frame_cache *trad_cache
66    = tramp_frame_cache (next_frame, this_cache);
67  trad_frame_get_id (trad_cache, this_id);
68}
69
70static void
71tramp_frame_prev_register (struct frame_info *next_frame,
72			   void **this_cache,
73			   int prev_regnum,
74			   int *optimizedp,
75			   enum lval_type * lvalp,
76			   CORE_ADDR *addrp,
77			   int *realnump, gdb_byte *valuep)
78{
79  struct trad_frame_cache *trad_cache
80    = tramp_frame_cache (next_frame, this_cache);
81  trad_frame_get_register (trad_cache, next_frame, prev_regnum, optimizedp,
82			   lvalp, addrp, realnump, valuep);
83}
84
85static CORE_ADDR
86tramp_frame_start (const struct tramp_frame *tramp,
87		   struct frame_info *next_frame, CORE_ADDR pc)
88{
89  int ti;
90  /* Search through the trampoline for one that matches the
91     instruction sequence around PC.  */
92  for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
93    {
94      CORE_ADDR func = pc - tramp->insn_size * ti;
95      int i;
96      for (i = 0; 1; i++)
97	{
98	  gdb_byte buf[sizeof (tramp->insn[0])];
99	  ULONGEST insn;
100	  if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
101	    return func;
102	  if (!safe_frame_unwind_memory (next_frame,
103					 func + i * tramp->insn_size,
104					 buf, tramp->insn_size))
105	    break;
106	  insn = extract_unsigned_integer (buf, tramp->insn_size);
107	  if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
108	    break;
109	}
110    }
111  /* Trampoline doesn't match.  */
112  return 0;
113}
114
115static int
116tramp_frame_sniffer (const struct frame_unwind *self,
117		     struct frame_info *next_frame,
118		     void **this_cache)
119{
120  const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
121  CORE_ADDR pc = frame_pc_unwind (next_frame);
122  CORE_ADDR func;
123  struct tramp_frame_cache *tramp_cache;
124
125  /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
126     section, then this is not a trampoline.  However, this assumption is
127     false on HPUX which has a signal trampoline that has a name; it can
128     also be false when using an alternative signal stack.  */
129  func = tramp_frame_start (tramp, next_frame, pc);
130  if (func == 0)
131    return 0;
132  tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
133  tramp_cache->func = func;
134  tramp_cache->tramp_frame = tramp;
135  (*this_cache) = tramp_cache;
136  return 1;
137}
138
139void
140tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
141			      const struct tramp_frame *tramp_frame)
142{
143  struct frame_data *data;
144  struct frame_unwind *unwinder;
145  int i;
146
147  /* Check that the instruction sequence contains a sentinel.  */
148  for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
149    {
150      if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
151	break;
152    }
153  gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
154  gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
155
156  data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
157  unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
158
159  data->tramp_frame = tramp_frame;
160  unwinder->type = tramp_frame->frame_type;
161  unwinder->unwind_data = data;
162  unwinder->sniffer = tramp_frame_sniffer;
163  unwinder->this_id = tramp_frame_this_id;
164  unwinder->prev_register = tramp_frame_prev_register;
165  frame_unwind_prepend_unwinder (gdbarch, unwinder);
166}
167