1 /* libunwind - a platform-independent unwind library
2 Copyright (C) 2003-2004 Hewlett-Packard Co
3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4
5 This file is part of libunwind.
6
7 Permission is hereby granted, free of charge, to any person obtaining
8 a copy of this software and associated documentation files (the
9 "Software"), to deal in the Software without restriction, including
10 without limitation the rights to use, copy, modify, merge, publish,
11 distribute, sublicense, and/or sell copies of the Software, and to
12 permit persons to whom the Software is furnished to do so, subject to
13 the following conditions:
14
15 The above copyright notice and this permission notice shall be
16 included in all copies or substantial portions of the Software.
17
18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
22 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
23 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
24 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
25 #include <elf.h>
26 #include <fcntl.h>
27 #include <string.h>
28 #include <unistd.h>
29
30 #include <sys/mman.h>
31
32 #include "libunwind_i.h"
33 #include "elf64.h"
34
35 static unw_word_t
find_gp(struct elf_dyn_info * edi,Elf64_Phdr * pdyn,Elf64_Addr load_base)36 find_gp (struct elf_dyn_info *edi, Elf64_Phdr *pdyn, Elf64_Addr load_base)
37 {
38 Elf64_Off soff, str_soff;
39 Elf64_Ehdr *ehdr = edi->ei.image;
40 Elf64_Shdr *shdr;
41 Elf64_Shdr *str_shdr;
42 Elf64_Addr gp = 0;
43 char *strtab;
44 int i;
45
46 if (pdyn)
47 {
48 /* If we have a PT_DYNAMIC program header, fetch the gp-value
49 from the DT_PLTGOT entry. */
50 Elf64_Dyn *dyn = (Elf64_Dyn *) (pdyn->p_offset + (char *) edi->ei.image);
51 for (; dyn->d_tag != DT_NULL; ++dyn)
52 if (dyn->d_tag == DT_PLTGOT)
53 {
54 gp = (Elf64_Addr) dyn->d_un.d_ptr + load_base;
55 goto done;
56 }
57 }
58
59 /* Without a PT_DYAMIC header, lets try to look for a non-empty .opd
60 section. If there is such a section, we know it's full of
61 function descriptors, and we can simply pick up the gp from the
62 second word of the first entry in this table. */
63
64 soff = ehdr->e_shoff;
65 str_soff = soff + (ehdr->e_shstrndx * ehdr->e_shentsize);
66
67 if (soff + ehdr->e_shnum * ehdr->e_shentsize > edi->ei.size)
68 {
69 Debug (1, "section table outside of image? (%lu > %lu)",
70 soff + ehdr->e_shnum * ehdr->e_shentsize,
71 edi->ei.size);
72 goto done;
73 }
74
75 shdr = (Elf64_Shdr *) ((char *) edi->ei.image + soff);
76 str_shdr = (Elf64_Shdr *) ((char *) edi->ei.image + str_soff);
77 strtab = (char *) edi->ei.image + str_shdr->sh_offset;
78 for (i = 0; i < ehdr->e_shnum; ++i)
79 {
80 if (strcmp (strtab + shdr->sh_name, ".opd") == 0
81 && shdr->sh_size >= 16)
82 {
83 gp = ((Elf64_Addr *) ((char *) edi->ei.image + shdr->sh_offset))[1];
84 goto done;
85 }
86 shdr = (Elf64_Shdr *) (((char *) shdr) + ehdr->e_shentsize);
87 }
88
89 done:
90 Debug (16, "image at %p, gp = %lx\n", edi->ei.image, gp);
91 return gp;
92 }
93
94 int
ia64_find_unwind_table(struct elf_dyn_info * edi,unw_addr_space_t as,char * path,unw_word_t segbase,unw_word_t mapoff,unw_word_t ip)95 ia64_find_unwind_table (struct elf_dyn_info *edi, unw_addr_space_t as,
96 char *path, unw_word_t segbase, unw_word_t mapoff,
97 unw_word_t ip)
98 {
99 Elf64_Phdr *phdr, *ptxt = NULL, *punw = NULL, *pdyn = NULL;
100 Elf64_Ehdr *ehdr;
101 int i;
102
103 if (!_Uelf64_valid_object (&edi->ei))
104 return -UNW_ENOINFO;
105
106 ehdr = edi->ei.image;
107 phdr = (Elf64_Phdr *) ((char *) edi->ei.image + ehdr->e_phoff);
108
109 for (i = 0; i < ehdr->e_phnum; ++i)
110 {
111 switch (phdr[i].p_type)
112 {
113 case PT_LOAD:
114 if (phdr[i].p_offset == mapoff)
115 ptxt = phdr + i;
116 break;
117
118 case PT_IA_64_UNWIND:
119 punw = phdr + i;
120 break;
121
122 case PT_DYNAMIC:
123 pdyn = phdr + i;
124 break;
125
126 default:
127 break;
128 }
129 }
130 if (!ptxt || !punw)
131 return 0;
132
133 edi->di_cache.start_ip = segbase;
134 edi->di_cache.end_ip = edi->di_cache.start_ip + ptxt->p_memsz;
135 edi->di_cache.gp = find_gp (edi, pdyn, segbase - ptxt->p_vaddr);
136 edi->di_cache.format = UNW_INFO_FORMAT_TABLE;
137 edi->di_cache.u.ti.name_ptr = 0;
138 edi->di_cache.u.ti.segbase = segbase;
139 edi->di_cache.u.ti.table_len = punw->p_memsz / sizeof (unw_word_t);
140 edi->di_cache.u.ti.table_data = (unw_word_t *)
141 ((char *) edi->ei.image + (punw->p_vaddr - ptxt->p_vaddr));
142 return 1;
143 }
144