1/* Signal trampoline unwinder.
2
3   Copyright (C) 2004-2020 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#ifndef TRAMP_FRAME_H
21#define TRAMP_FRAME_H
22
23#include "frame.h"		/* For "enum frame_type".  */
24
25struct trad_frame;
26struct frame_info;
27struct trad_frame_cache;
28
29/* A trampoline consists of a small sequence of instructions placed at
30   an unspecified location in the inferior's address space.  The only
31   identifying attribute of the trampoline's address is that it does
32   not fall inside an object file's section.
33
34   The only way to identify a trampoline is to perform a brute force
35   examination of the instructions at and around the PC.
36
37   This module provides a convenient interface for performing that
38   operation.  */
39
40/* A trampoline descriptor.  */
41
42/* Magic instruction that to mark the end of the signal trampoline
43   instruction sequence.  */
44#define TRAMP_SENTINEL_INSN ULONGEST_MAX
45
46struct tramp_frame
47{
48  /* The trampoline's type, some a signal trampolines, some are normal
49     call-frame trampolines (aka thunks).  */
50  enum frame_type frame_type;
51  /* The trampoline's entire instruction sequence.  It consists of a
52     bytes/mask pair.  Search for this in the inferior at or around
53     the frame's PC.  It is assumed that the PC is INSN_SIZE aligned,
54     and that each element of TRAMP contains one INSN_SIZE
55     instruction.  It is also assumed that INSN[0] contains the first
56     instruction of the trampoline and hence the address of the
57     instruction matching INSN[0] is the trampoline's "func" address.
58     The instruction sequence is terminated by
59     TRAMP_SENTINEL_INSN.  */
60  int insn_size;
61  struct
62  {
63    ULONGEST bytes;
64    ULONGEST mask;
65  } insn[48];
66  /* Initialize a trad-frame cache corresponding to the tramp-frame.
67     FUNC is the address of the instruction TRAMP[0] in memory.  */
68  void (*init) (const struct tramp_frame *self,
69		struct frame_info *this_frame,
70		struct trad_frame_cache *this_cache,
71		CORE_ADDR func);
72  /* Return non-zero if the tramp-frame is valid for the PC requested.
73     Adjust the PC to point to the address to check the instruction
74     sequence against if required.  If this is NULL, then the tramp-frame
75     is valid for any PC.  */
76  int (*validate) (const struct tramp_frame *self,
77		   struct frame_info *this_frame,
78		   CORE_ADDR *pc);
79};
80
81void tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
82				   const struct tramp_frame *tramp);
83
84#endif
85