1/* Copyright (C) 2000-2015 Free Software Foundation, Inc.
2   Contributed by Richard Henderson <rth@cygnus.com>.
3
4   This file is part of GCC.
5
6   GCC is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3, or (at your option)
9   any later version.
10
11   GCC is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   Under Section 7 of GPL version 3, you are granted additional
17   permissions described in the GCC Runtime Library Exception, version
18   3.1, as published by the Free Software Foundation.
19
20   You should have received a copy of the GNU General Public License and
21   a copy of the GCC Runtime Library Exception along with this program;
22   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23   <http://www.gnu.org/licenses/>.  */
24
25/* Locate the FDE entry for a given address, using glibc ld.so routines
26   to avoid register/deregister calls at DSO load/unload.  */
27
28#ifndef _GNU_SOURCE
29#define _GNU_SOURCE 1
30#endif
31#include "config.h"
32#include <stddef.h>
33#include <stdlib.h>
34#include <link.h>
35#include "unwind-ia64.h"
36
37#if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 2) \
38    || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && !defined(DT_CONFIG))
39# error You need GLIBC 2.2.4 or later on IA-64 Linux
40#endif
41
42struct unw_ia64_callback_data
43{
44  Elf64_Addr pc;
45  unsigned long *segment_base;
46  unsigned long *gp;
47  struct unw_table_entry *ret;
48};
49
50static int
51_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
52{
53  struct unw_ia64_callback_data *data = (struct unw_ia64_callback_data *) ptr;
54  const Elf64_Phdr *phdr, *p_unwind, *p_dynamic;
55  long n, match;
56  Elf64_Addr load_base, seg_base;
57  struct unw_table_entry *f_base, *f;
58  size_t lo, hi;
59
60  /* Make sure struct dl_phdr_info is at least as big as we need.  */
61  if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
62	     + sizeof (info->dlpi_phnum))
63    return -1;
64
65  match = 0;
66  phdr = info->dlpi_phdr;
67  load_base = info->dlpi_addr;
68  p_unwind = NULL;
69  p_dynamic = NULL;
70  seg_base = ~(Elf64_Addr) 0;
71
72  /* See if PC falls into one of the loaded segments.  Find the unwind
73     segment at the same time.  */
74  for (n = info->dlpi_phnum; --n >= 0; phdr++)
75    {
76      if (phdr->p_type == PT_LOAD)
77	{
78	  Elf64_Addr vaddr = phdr->p_vaddr + load_base;
79	  if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
80	    match = 1;
81	  if (vaddr < seg_base)
82	    seg_base = vaddr;
83	}
84      else if (phdr->p_type == PT_IA_64_UNWIND)
85	p_unwind = phdr;
86      else if (phdr->p_type == PT_DYNAMIC)
87	p_dynamic = phdr;
88    }
89  if (!match || !p_unwind)
90    return 0;
91
92  /* Search for the FDE within the unwind segment.  */
93
94  f_base = (struct unw_table_entry *) (p_unwind->p_vaddr + load_base);
95  lo = 0;
96  hi = p_unwind->p_memsz / sizeof (struct unw_table_entry);
97
98  while (lo < hi)
99    {
100      size_t mid = (lo + hi) / 2;
101
102      f = f_base + mid;
103      if (data->pc < f->start_offset + seg_base)
104	hi = mid;
105      else if (data->pc >= f->end_offset + seg_base)
106	lo = mid + 1;
107      else
108        goto found;
109    }
110  /* No need to search for further libraries when we know pc is contained
111     in this library.  */
112  return 1;
113
114 found:
115  *data->segment_base = seg_base;
116  *data->gp = 0;
117  data->ret = f;
118
119  if (p_dynamic)
120    {
121      /* For dynamically linked executables and shared libraries,
122	 DT_PLTGOT is the gp value for that object.  */
123      Elf64_Dyn *dyn = (Elf64_Dyn *)(p_dynamic->p_vaddr + load_base);
124      for (; dyn->d_tag != DT_NULL ; dyn++)
125	if (dyn->d_tag == DT_PLTGOT)
126	  {
127	    /* On IA-64, _DYNAMIC is writable and GLIBC has relocated it.  */
128	    *data->gp = dyn->d_un.d_ptr;
129	    break;
130	  }
131    }
132  else
133    {
134      /* Otherwise this is a static executable with no _DYNAMIC.
135	 The gp is constant program-wide.  */
136      register unsigned long gp __asm__("gp");
137      *data->gp = gp;
138    }
139
140  return 1;
141}
142
143/* Return a pointer to the unwind table entry for the function
144   containing PC.  */
145
146struct unw_table_entry *
147_Unwind_FindTableEntry (void *pc, unw_word *segment_base, unw_word *gp,
148                        struct unw_table_entry *ent ATTRIBUTE_UNUSED)
149{
150  struct unw_ia64_callback_data data;
151
152  data.pc = (Elf64_Addr) pc;
153  data.segment_base = segment_base;
154  data.gp = gp;
155  data.ret = NULL;
156
157  if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
158    return NULL;
159
160  return data.ret;
161}
162