1/* Find entry breakpoint locations for a function.
2   Copyright (C) 2005-2009 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4
5   Red Hat elfutils is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by the
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8
9   Red Hat elfutils is distributed in the hope that it will be useful, but
10   WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   General Public License for more details.
13
14   You should have received a copy of the GNU General Public License along
15   with Red Hat elfutils; if not, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18   In addition, as a special exception, Red Hat, Inc. gives You the
19   additional right to link the code of Red Hat elfutils with code licensed
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35   code used in conjunction with Red Hat elfutils except the Non-GPL Code
36   covered by this exception.  If you modify this file, you may extend this
37   exception to your version of the file, but you are not obligated to do
38   so.  If you do not wish to provide this exception without modification,
39   you must delete this exception statement from your version and license
40   this file solely under the GPL without exception.
41
42   Red Hat elfutils is an included package of the Open Invention Network.
43   An included package of the Open Invention Network is a package for which
44   Open Invention Network licensees cross-license their patents.  No patent
45   license is granted, either expressly or impliedly, by designation as an
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48   <http://www.openinventionnetwork.com>.  */
49
50#ifdef HAVE_CONFIG_H
51# include <config.h>
52#endif
53#include "libdwP.h"
54#include <dwarf.h>
55#include <stdlib.h>
56
57
58int
59dwarf_entry_breakpoints (die, bkpts)
60     Dwarf_Die *die;
61     Dwarf_Addr **bkpts;
62{
63  int nbkpts = 0;
64  *bkpts = NULL;
65
66  /* Add one breakpoint location to the result vector.  */
67  inline int add_bkpt (Dwarf_Addr pc)
68    {
69      Dwarf_Addr *newlist = realloc (*bkpts, ++nbkpts * sizeof newlist[0]);
70      if (newlist == NULL)
71	{
72	  free (*bkpts);
73	  *bkpts = NULL;
74	  __libdw_seterrno (DWARF_E_NOMEM);
75	  return -1;
76	}
77      newlist[nbkpts - 1] = pc;
78      *bkpts = newlist;
79      return nbkpts;
80    }
81
82  /* Fallback result, break at the entrypc/lowpc value.  */
83  inline int entrypc_bkpt (void)
84    {
85      Dwarf_Addr pc;
86      return INTUSE(dwarf_entrypc) (die, &pc) < 0 ? -1 : add_bkpt (pc);
87    }
88
89  /* Fetch the CU's line records to look for this DIE's addresses.  */
90  Dwarf_Die cudie = CUDIE (die->cu);
91  Dwarf_Lines *lines;
92  size_t nlines;
93  if (INTUSE(dwarf_getsrclines) (&cudie, &lines, &nlines) < 0)
94    {
95      int error = INTUSE (dwarf_errno) ();
96      if (error == 0)		/* CU has no DW_AT_stmt_list.  */
97	return entrypc_bkpt ();
98      __libdw_seterrno (error);
99      return -1;
100    }
101
102  /* Search a contiguous PC range for prologue-end markers.
103     If DWARF, look for proper markers.
104     Failing that, if ADHOC, look for the ad hoc convention.  */
105  inline int search_range (Dwarf_Addr low, Dwarf_Addr high,
106			   bool dwarf, bool adhoc)
107    {
108      size_t l = 0, u = nlines;
109      while (l < u)
110	{
111	  size_t idx = (l + u) / 2;
112	  if (lines->info[idx].addr < low)
113	    l = idx + 1;
114	  else if (lines->info[idx].addr > low)
115	    u = idx;
116	  else if (lines->info[idx].end_sequence)
117	    l = idx + 1;
118	  else
119	    {
120	      l = idx;
121	      break;
122	    }
123	}
124      if (l < u)
125	{
126	  if (dwarf)
127	    for (size_t i = l; i < u && lines->info[i].addr < high; ++i)
128	      if (lines->info[i].prologue_end
129		  && add_bkpt (lines->info[i].addr) < 0)
130		return -1;
131	  if (adhoc && nbkpts == 0)
132	    while (++l < nlines && lines->info[l].addr < high)
133	      if (!lines->info[l].end_sequence)
134		return add_bkpt (lines->info[l].addr);
135	  return nbkpts;
136	}
137      __libdw_seterrno (DWARF_E_INVALID_DWARF);
138      return -1;
139    }
140
141  /* Search each contiguous address range for DWARF prologue_end markers.  */
142
143  Dwarf_Addr base;
144  Dwarf_Addr begin;
145  Dwarf_Addr end;
146  ptrdiff_t offset = INTUSE(dwarf_ranges) (die, 0, &base, &begin, &end);
147  if (offset < 0)
148    return -1;
149
150  /* Most often there is a single contiguous PC range for the DIE.  */
151  if (offset == 1)
152    return search_range (begin, end, true, true) ?: entrypc_bkpt ();
153
154  Dwarf_Addr lowpc = (Dwarf_Addr) -1l;
155  Dwarf_Addr highpc = (Dwarf_Addr) -1l;
156  while (offset > 0)
157    {
158      /* We have an address range entry.  */
159      if (search_range (begin, end, true, false) < 0)
160	return -1;
161
162      if (begin < lowpc)
163	{
164	  lowpc = begin;
165	  highpc = end;
166	}
167
168      offset = INTUSE(dwarf_ranges) (die, offset, &base, &begin, &end);
169    }
170
171  /* If we didn't find any proper DWARF markers, then look in the
172     lowest-addressed range for an ad hoc marker.  Failing that,
173     fall back to just using the entrypc value.  */
174  return (nbkpts
175	  ?: (lowpc == (Dwarf_Addr) -1l ? 0
176	      : search_range (lowpc, highpc, false, true))
177	  ?: entrypc_bkpt ());
178}
179