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
33 struct frame_data
34 {
35 const struct tramp_frame *tramp_frame;
36 };
37
38 struct tramp_frame_cache
39 {
40 CORE_ADDR func;
41 const struct tramp_frame *tramp_frame;
42 struct trad_frame_cache *trad_cache;
43 };
44
45 static struct trad_frame_cache *
tramp_frame_cache(struct frame_info * next_frame,void ** this_cache)46 tramp_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
62 static void
tramp_frame_this_id(struct frame_info * next_frame,void ** this_cache,struct frame_id * this_id)63 tramp_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
72 static void
tramp_frame_prev_register(struct frame_info * next_frame,void ** this_cache,int prev_regnum,int * optimizedp,enum lval_type * lvalp,CORE_ADDR * addrp,int * realnump,void * valuep)73 tramp_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
87 static CORE_ADDR
tramp_frame_start(const struct tramp_frame * tramp,struct frame_info * next_frame,CORE_ADDR pc)88 tramp_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
117 static int
tramp_frame_sniffer(const struct frame_unwind * self,struct frame_info * next_frame,void ** this_cache)118 tramp_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
148 void
tramp_frame_prepend_unwinder(struct gdbarch * gdbarch,const struct tramp_frame * tramp_frame)149 tramp_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