summaryrefslogtreecommitdiff
path: root/libdw/dwarf_getscopes.c
blob: 833f1ac504d2608fa4ad4a3dc3566c5ed89178b8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
/* Return scope DIEs containing PC address.
   Copyright (C) 2005, 2007, 2015 Red Hat, Inc.
   Copyright (C) 2023 Mark J. Wielaard <mark@klomp.org>
   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify
   it under the terms of either

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at
       your option) any later version

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at
       your option) any later version

   or both in parallel, as here.

   elfutils is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <stdlib.h>
#include "libdwP.h"
#include <dwarf.h>


struct args
{
  Dwarf_Addr pc;
  Dwarf_Die *scopes;
  unsigned int inlined, nscopes;
  Dwarf_Die inlined_origin;
};

/* Preorder visitor: prune the traversal if this DIE does not contain PC.  */
static int
pc_match (unsigned int depth, struct Dwarf_Die_Chain *die, void *arg)
{
  struct args *a = arg;

  if (a->scopes != NULL)
    die->prune = true;
  else
    {
      /* dwarf_haspc returns an error if there are no appropriate attributes.
	 But we use it indiscriminantly instead of presuming which tags can
	 have PC attributes.  So when it fails for that reason, treat it just
	 as a nonmatching return.  */
      int result = INTUSE(dwarf_haspc) (&die->die, a->pc);
      if (result < 0)
	{
	  int error = INTUSE(dwarf_errno) ();
	  if (error != DWARF_E_NOERROR
	      && error != DWARF_E_NO_DEBUG_RANGES
	      && error != DWARF_E_NO_DEBUG_RNGLISTS)
	    {
	      __libdw_seterrno (error);
	      return -1;
	    }
	  result = 0;
	}
      if (result == 0)
    	die->prune = true;

      if (!die->prune
	  && INTUSE (dwarf_tag) (&die->die) == DW_TAG_inlined_subroutine)
	a->inlined = depth;
    }

  return 0;
}

/* Preorder visitor for second partial traversal after finding a
   concrete inlined instance.  */
static int
origin_match (unsigned int depth, struct Dwarf_Die_Chain *die, void *arg)
{
  struct args *a = arg;

  if (die->die.addr != a->inlined_origin.addr)
    return 0;

  /* We have a winner!  This is the abstract definition of the inline
     function of which A->scopes[A->nscopes - 1] is a concrete instance.
  */

  unsigned int nscopes = a->nscopes + depth;
  Dwarf_Die *scopes = realloc (a->scopes, nscopes * sizeof scopes[0]);
  if (scopes == NULL)
    {
      free (a->scopes);
      __libdw_seterrno (DWARF_E_NOMEM);
      return -1;
    }

  a->scopes = scopes;
  do
    {
      die = die->parent;
      scopes[a->nscopes++] = die->die;
    }
  while (a->nscopes < nscopes);
  assert (die->parent == NULL);
  return a->nscopes;
}

/* Postorder visitor: first (innermost) call wins.  */
static int
pc_record (unsigned int depth, struct Dwarf_Die_Chain *die, void *arg)
{
  struct args *a = arg;

  if (die->prune)
    return 0;

  if (a->scopes == NULL)
    {
      /* We have hit the innermost DIE that contains the target PC.  */

      a->nscopes = depth + 1 - a->inlined;
      a->scopes = malloc (a->nscopes * sizeof a->scopes[0]);
      if (a->scopes == NULL)
	{
	  __libdw_seterrno (DWARF_E_NOMEM);
	  return -1;
	}

      for (unsigned int i = 0; i < a->nscopes; ++i)
	{
	  a->scopes[i] = die->die;
	  die = die->parent;
	}

      if (a->inlined == 0)
	{
	  assert (die == NULL);
	  return a->nscopes;
	}

      /* This is the concrete inlined instance itself.
	 Record its abstract_origin pointer.  */
      Dwarf_Die *const inlinedie = &a->scopes[depth - a->inlined];

      assert (INTUSE (dwarf_tag) (inlinedie) == DW_TAG_inlined_subroutine);
      Dwarf_Attribute attr_mem;
      Dwarf_Attribute *attr = INTUSE (dwarf_attr) (inlinedie,
						   DW_AT_abstract_origin,
						   &attr_mem);
      if (INTUSE (dwarf_formref_die) (attr, &a->inlined_origin) == NULL)
	return -1;
      return 0;
    }


  /* We've recorded the scopes back to one that is a concrete inlined
     instance.  Now return out of the traversal back to the scope
     containing that instance.  */

  assert (a->inlined);
  if (depth >= a->inlined)
    /* Not there yet.  */
    return 0;

  /* This is the innermost inline scope, we are done here.  */
  return a->nscopes;
}


int
dwarf_getscopes (Dwarf_Die *cudie, Dwarf_Addr pc, Dwarf_Die **scopes)
{
  if (cudie == NULL)
    return -1;

  struct Dwarf_Die_Chain cu = { .parent = NULL, .die = *cudie };
  struct args a = { .pc = pc };

  int result = __libdw_visit_scopes (0, &cu, NULL, &pc_match, &pc_record, &a);

  if (result >= 0 && a.scopes != NULL && a.inlined > 0)
    {
      /* We like the find the inline function's abstract definition
         scope, but that might be in a different CU.  */
      cu.die = CUDIE (a.inlined_origin.cu);
      result = __libdw_visit_scopes (0, &cu, NULL, &origin_match, NULL, &a);
    }

  if (result > 0)
    *scopes = a.scopes;

  return result;
}