1 /* Copyright (C) 2000-2023 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 #ifndef inhibit_libc
33 #include <stddef.h>
34 #include <stdlib.h>
35 #include <link.h>
36 #include "unwind-ia64.h"
37
38 #if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 2) \
39 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && !defined(DT_CONFIG))
40 # error You need GLIBC 2.2.4 or later on IA-64 Linux
41 #endif
42
43 struct unw_ia64_callback_data
44 {
45 Elf64_Addr pc;
46 unsigned long *segment_base;
47 unsigned long *gp;
48 struct unw_table_entry *ret;
49 };
50
51 static int
52 _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
53 {
54 struct unw_ia64_callback_data *data = (struct unw_ia64_callback_data *) ptr;
55 const Elf64_Phdr *phdr, *p_unwind, *p_dynamic;
56 long n, match;
57 Elf64_Addr load_base, seg_base;
58 struct unw_table_entry *f_base, *f;
59 size_t lo, hi;
60
61 /* Make sure struct dl_phdr_info is at least as big as we need. */
62 if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
63 + sizeof (info->dlpi_phnum))
64 return -1;
65
66 match = 0;
67 phdr = info->dlpi_phdr;
68 load_base = info->dlpi_addr;
69 p_unwind = NULL;
70 p_dynamic = NULL;
71 seg_base = ~(Elf64_Addr) 0;
72
73 /* See if PC falls into one of the loaded segments. Find the unwind
74 segment at the same time. */
75 for (n = info->dlpi_phnum; --n >= 0; phdr++)
76 {
77 if (phdr->p_type == PT_LOAD)
78 {
79 Elf64_Addr vaddr = phdr->p_vaddr + load_base;
80 if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
81 match = 1;
82 if (vaddr < seg_base)
83 seg_base = vaddr;
84 }
85 else if (phdr->p_type == PT_IA_64_UNWIND)
86 p_unwind = phdr;
87 else if (phdr->p_type == PT_DYNAMIC)
88 p_dynamic = phdr;
89 }
90 if (!match || !p_unwind)
91 return 0;
92
93 /* Search for the FDE within the unwind segment. */
94
95 f_base = (struct unw_table_entry *) (p_unwind->p_vaddr + load_base);
96 lo = 0;
97 hi = p_unwind->p_memsz / sizeof (struct unw_table_entry);
98
99 while (lo < hi)
100 {
101 size_t mid = (lo + hi) / 2;
102
103 f = f_base + mid;
104 if (data->pc < f->start_offset + seg_base)
105 hi = mid;
106 else if (data->pc >= f->end_offset + seg_base)
107 lo = mid + 1;
108 else
109 goto found;
110 }
111 /* No need to search for further libraries when we know pc is contained
112 in this library. */
113 return 1;
114
115 found:
116 *data->segment_base = seg_base;
117 *data->gp = 0;
118 data->ret = f;
119
120 if (p_dynamic)
121 {
122 /* For dynamically linked executables and shared libraries,
123 DT_PLTGOT is the gp value for that object. */
124 Elf64_Dyn *dyn = (Elf64_Dyn *)(p_dynamic->p_vaddr + load_base);
125 for (; dyn->d_tag != DT_NULL ; dyn++)
126 if (dyn->d_tag == DT_PLTGOT)
127 {
128 /* On IA-64, _DYNAMIC is writable and GLIBC has relocated it. */
129 *data->gp = dyn->d_un.d_ptr;
130 break;
131 }
132 }
133 else
134 {
135 /* Otherwise this is a static executable with no _DYNAMIC.
136 The gp is constant program-wide. */
137 register unsigned long gp __asm__("gp");
138 *data->gp = gp;
139 }
140
141 return 1;
142 }
143
144 /* Return a pointer to the unwind table entry for the function
145 containing PC. */
146
147 struct unw_table_entry *
148 _Unwind_FindTableEntry (void *pc, unw_word *segment_base, unw_word *gp,
149 struct unw_table_entry *ent ATTRIBUTE_UNUSED)
150 {
151 struct unw_ia64_callback_data data;
152
153 data.pc = (Elf64_Addr) pc;
154 data.segment_base = segment_base;
155 data.gp = gp;
156 data.ret = NULL;
157
158 if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
159 return NULL;
160
161 return data.ret;
162 }
163 #endif