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>
5 This file is part of libunwind.
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:
15 The above copyright notice and this permission notice shall be
16 included in all copies or substantial portions of the Software.
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. */
32 #include "libunwind_i.h"
37 dwarf_find_unwind_table (struct elf_dyn_info *edi, unw_addr_space_t as,
38 char *path, unw_word_t segbase, unw_word_t mapoff,
41 Elf_W(Phdr) *phdr, *ptxt = NULL, *peh_hdr = NULL, *pdyn = NULL;
42 unw_word_t addr, eh_frame_start, fde_count, load_base;
43 unw_word_t max_load_addr = 0;
44 unw_word_t start_ip = (unw_word_t) -1;
45 unw_word_t end_ip = 0;
46 struct dwarf_eh_frame_hdr *hdr;
51 const Elf_W(Phdr) *parm_exidx = NULL;
53 int i, ret, found = 0;
55 /* XXX: Much of this code is Linux/LSB-specific. */
57 if (!elf_w(valid_object) (&edi->ei))
61 phdr = (Elf_W(Phdr) *) ((char *) edi->ei.image + ehdr->e_phoff);
63 for (i = 0; i < ehdr->e_phnum; ++i)
65 switch (phdr[i].p_type)
68 if (phdr[i].p_vaddr < start_ip)
69 start_ip = phdr[i].p_vaddr;
71 if (phdr[i].p_vaddr + phdr[i].p_memsz > end_ip)
72 end_ip = phdr[i].p_vaddr + phdr[i].p_memsz;
74 if (phdr[i].p_offset == mapoff)
76 if ((uintptr_t) edi->ei.image + phdr->p_filesz > max_load_addr)
77 max_load_addr = (uintptr_t) edi->ei.image + phdr->p_filesz;
90 parm_exidx = phdr + i;
102 load_base = segbase - ptxt->p_vaddr;
103 start_ip += load_base;
110 /* For dynamicly linked executables and shared libraries,
111 DT_PLTGOT is the value that data-relative addresses are
112 relative to for that object. We call this the "gp". */
113 Elf_W(Dyn) *dyn = (Elf_W(Dyn) *)(pdyn->p_offset
114 + (char *) edi->ei.image);
115 for (; dyn->d_tag != DT_NULL; ++dyn)
116 if (dyn->d_tag == DT_PLTGOT)
118 /* Assume that _DYNAMIC is writable and GLIBC has
119 relocated it (true for x86 at least). */
120 edi->di_cache.gp = dyn->d_un.d_ptr;
125 /* Otherwise this is a static executable with no _DYNAMIC. Assume
126 that data-relative addresses are relative to 0, i.e.,
128 edi->di_cache.gp = 0;
130 hdr = (struct dwarf_eh_frame_hdr *) (peh_hdr->p_offset
131 + (char *) edi->ei.image);
132 if (hdr->version != DW_EH_VERSION)
134 Debug (1, "table `%s' has unexpected version %d\n",
139 a = unw_get_accessors (unw_local_addr_space);
140 addr = (unw_word_t) (hdr + 1);
142 /* Fill in a dummy proc_info structure. We just need to fill in
143 enough to ensure that dwarf_read_encoded_pointer() can do it's
144 job. Since we don't have a procedure-context at this point, all
145 we have to do is fill in the global-pointer. */
146 memset (&pi, 0, sizeof (pi));
147 pi.gp = edi->di_cache.gp;
149 /* (Optionally) read eh_frame_ptr: */
150 if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
151 &addr, hdr->eh_frame_ptr_enc, &pi,
152 &eh_frame_start, NULL)) < 0)
155 /* (Optionally) read fde_count: */
156 if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
157 &addr, hdr->fde_count_enc, &pi,
158 &fde_count, NULL)) < 0)
161 if (hdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4))
166 unw_word_t eh_frame_end;
168 /* If there is no search table or it has an unsupported
169 encoding, fall back on linear search. */
170 if (hdr->table_enc == DW_EH_PE_omit)
171 Debug (4, "EH lacks search table; doing linear search\n");
173 Debug (4, "EH table has encoding 0x%x; doing linear search\n",
176 eh_frame_end = max_load_addr; /* XXX can we do better? */
178 if (hdr->fde_count_enc == DW_EH_PE_omit)
180 if (hdr->eh_frame_ptr_enc == DW_EH_PE_omit)
183 return linear_search (unw_local_addr_space, ip,
184 eh_frame_start, eh_frame_end, fde_count,
185 pi, need_unwind_info, NULL);
189 edi->di_cache.start_ip = start_ip;
190 edi->di_cache.end_ip = end_ip;
191 edi->di_cache.format = UNW_INFO_FORMAT_REMOTE_TABLE;
192 edi->di_cache.u.rti.name_ptr = 0;
193 /* two 32-bit values (ip_offset/fde_offset) per table-entry: */
194 edi->di_cache.u.rti.table_len = (fde_count * 8) / sizeof (unw_word_t);
195 edi->di_cache.u.rti.table_data = ((load_base + peh_hdr->p_vaddr)
196 + (addr - (unw_word_t) edi->ei.image
197 - peh_hdr->p_offset));
199 /* For the binary-search table in the eh_frame_hdr, data-relative
200 means relative to the start of that section... */
201 edi->di_cache.u.rti.segbase = ((load_base + peh_hdr->p_vaddr)
202 + ((unw_word_t) hdr - (unw_word_t) edi->ei.image
203 - peh_hdr->p_offset));
210 edi->di_arm.format = UNW_INFO_FORMAT_ARM_EXIDX;
211 edi->di_arm.start_ip = start_ip;
212 edi->di_arm.end_ip = end_ip;
213 edi->di_arm.u.rti.name_ptr = (unw_word_t) path;
214 edi->di_arm.u.rti.table_data = load_base + parm_exidx->p_vaddr;
215 edi->di_arm.u.rti.table_len = parm_exidx->p_memsz;
220 #ifdef CONFIG_DEBUG_FRAME
221 /* Try .debug_frame. */
222 found = dwarf_find_debug_frame (found, &edi->di_debug, ip, load_base, path,