1/* Copyright (C) 2000, 2001, 2003 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 2, 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   You should have received a copy of the GNU General Public License
17   along with GCC; see the file COPYING.  If not, write to
18   the Free Software Foundation, 51 Franklin Street, Fifth Floor,
19   Boston, MA 02110-1301, USA.  */
20
21/* As a special exception, if you link this library with other files,
22   some of which are compiled with GCC, to produce an executable,
23   this library does not by itself cause the resulting executable
24   to be covered by the GNU General Public License.
25   This exception does not however invalidate any other reasons why
26   the executable file might be covered by the GNU General Public License.  */
27
28/* Locate the FDE entry for a given address, using glibc ld.so routines
29   to avoid register/deregister calls at DSO load/unload.  */
30
31#ifndef _GNU_SOURCE
32#define _GNU_SOURCE 1
33#endif
34#include "config.h"
35#include <stddef.h>
36#include <stdlib.h>
37#include <link.h>
38#include "unwind-ia64.h"
39
40#if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 2) \
41    || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && !defined(DT_CONFIG))
42# error You need GLIBC 2.2.4 or later on IA-64 Linux
43#endif
44
45struct unw_ia64_callback_data
46{
47  Elf64_Addr pc;
48  unsigned long *segment_base;
49  unsigned long *gp;
50  struct unw_table_entry *ret;
51};
52
53static int
54_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
55{
56  struct unw_ia64_callback_data *data = (struct unw_ia64_callback_data *) ptr;
57  const Elf64_Phdr *phdr, *p_unwind, *p_dynamic;
58  long n, match;
59  Elf64_Addr load_base, seg_base;
60  struct unw_table_entry *f_base, *f;
61  size_t lo, hi;
62
63  /* Make sure struct dl_phdr_info is at least as big as we need.  */
64  if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
65	     + sizeof (info->dlpi_phnum))
66    return -1;
67
68  match = 0;
69  phdr = info->dlpi_phdr;
70  load_base = info->dlpi_addr;
71  p_unwind = NULL;
72  p_dynamic = NULL;
73  seg_base = ~(Elf64_Addr) 0;
74
75  /* See if PC falls into one of the loaded segments.  Find the unwind
76     segment at the same time.  */
77  for (n = info->dlpi_phnum; --n >= 0; phdr++)
78    {
79      if (phdr->p_type == PT_LOAD)
80	{
81	  Elf64_Addr vaddr = phdr->p_vaddr + load_base;
82	  if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
83	    match = 1;
84	  if (vaddr < seg_base)
85	    seg_base = vaddr;
86	}
87      else if (phdr->p_type == PT_IA_64_UNWIND)
88	p_unwind = phdr;
89      else if (phdr->p_type == PT_DYNAMIC)
90	p_dynamic = phdr;
91    }
92  if (!match || !p_unwind)
93    return 0;
94
95  /* Search for the FDE within the unwind segment.  */
96
97  f_base = (struct unw_table_entry *) (p_unwind->p_vaddr + load_base);
98  lo = 0;
99  hi = p_unwind->p_memsz / sizeof (struct unw_table_entry);
100
101  while (lo < hi)
102    {
103      size_t mid = (lo + hi) / 2;
104
105      f = f_base + mid;
106      if (data->pc < f->start_offset + seg_base)
107	hi = mid;
108      else if (data->pc >= f->end_offset + seg_base)
109	lo = mid + 1;
110      else
111        goto found;
112    }
113  /* No need to search for further libraries when we know pc is contained
114     in this library.  */
115  return 1;
116
117 found:
118  *data->segment_base = seg_base;
119  *data->gp = 0;
120  data->ret = f;
121
122  if (p_dynamic)
123    {
124      /* For dynamically linked executables and shared libraries,
125	 DT_PLTGOT is the gp value for that object.  */
126      Elf64_Dyn *dyn = (Elf64_Dyn *)(p_dynamic->p_vaddr + load_base);
127      for (; dyn->d_tag != DT_NULL ; dyn++)
128	if (dyn->d_tag == DT_PLTGOT)
129	  {
130	    /* On IA-64, _DYNAMIC is writable and GLIBC has relocated it.  */
131	    *data->gp = dyn->d_un.d_ptr;
132	    break;
133	  }
134    }
135  else
136    {
137      /* Otherwise this is a static executable with no _DYNAMIC.
138	 The gp is constant program-wide.  */
139      register unsigned long gp __asm__("gp");
140      *data->gp = gp;
141    }
142
143  return 1;
144}
145
146/* Return a pointer to the unwind table entry for the function
147   containing PC.  */
148
149struct unw_table_entry *
150_Unwind_FindTableEntry (void *pc, unsigned long *segment_base,
151                        unsigned long *gp)
152{
153  struct unw_ia64_callback_data data;
154
155  data.pc = (Elf64_Addr) pc;
156  data.segment_base = segment_base;
157  data.gp = gp;
158  data.ret = NULL;
159
160  if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
161    return NULL;
162
163  return data.ret;
164}
165