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. */
33 #include "libunwind_i.h"
38 dwarf_find_unwind_table (struct elf_dyn_info *edi, unw_addr_space_t as,
39 char *path, unw_word_t segbase, unw_word_t mapoff,
42 Elf_W(Phdr) *phdr, *ptxt = NULL, *peh_hdr = NULL, *pdyn = NULL;
43 unw_word_t addr, eh_frame_start, fde_count, load_base;
44 unw_word_t max_load_addr = 0;
45 unw_word_t start_ip = (unw_word_t) -1;
46 unw_word_t end_ip = 0;
47 struct dwarf_eh_frame_hdr *hdr;
52 const Elf_W(Phdr) *parm_exidx = NULL;
54 int i, ret, found = 0;
56 /* XXX: Much of this code is Linux/LSB-specific. */
58 if (!elf_w(valid_object) (&edi->ei))
62 phdr = (Elf_W(Phdr) *) ((char *) edi->ei.image + ehdr->e_phoff);
64 for (i = 0; i < ehdr->e_phnum; ++i)
66 switch (phdr[i].p_type)
69 if (phdr[i].p_vaddr < start_ip)
70 start_ip = phdr[i].p_vaddr;
72 if (phdr[i].p_vaddr + phdr[i].p_memsz > end_ip)
73 end_ip = phdr[i].p_vaddr + phdr[i].p_memsz;
75 if (phdr[i].p_offset == mapoff)
77 if ((uintptr_t) edi->ei.image + phdr->p_filesz > max_load_addr)
78 max_load_addr = (uintptr_t) edi->ei.image + phdr->p_filesz;
91 parm_exidx = phdr + i;
103 load_base = segbase - ptxt->p_vaddr;
104 start_ip += load_base;
111 /* For dynamicly linked executables and shared libraries,
112 DT_PLTGOT is the value that data-relative addresses are
113 relative to for that object. We call this the "gp". */
114 Elf_W(Dyn) *dyn = (Elf_W(Dyn) *)(pdyn->p_offset
115 + (char *) edi->ei.image);
116 for (; dyn->d_tag != DT_NULL; ++dyn)
117 if (dyn->d_tag == DT_PLTGOT)
119 /* Assume that _DYNAMIC is writable and GLIBC has
120 relocated it (true for x86 at least). */
121 edi->di_cache.gp = dyn->d_un.d_ptr;
126 /* Otherwise this is a static executable with no _DYNAMIC. Assume
127 that data-relative addresses are relative to 0, i.e.,
129 edi->di_cache.gp = 0;
131 hdr = (struct dwarf_eh_frame_hdr *) (peh_hdr->p_offset
132 + (char *) edi->ei.image);
133 if (hdr->version != DW_EH_VERSION)
135 Debug (1, "table `%s' has unexpected version %d\n",
140 a = unw_get_accessors (unw_local_addr_space);
141 addr = (unw_word_t) (hdr + 1);
143 /* Fill in a dummy proc_info structure. We just need to fill in
144 enough to ensure that dwarf_read_encoded_pointer() can do it's
145 job. Since we don't have a procedure-context at this point, all
146 we have to do is fill in the global-pointer. */
147 memset (&pi, 0, sizeof (pi));
148 pi.gp = edi->di_cache.gp;
150 /* (Optionally) read eh_frame_ptr: */
151 if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
152 &addr, hdr->eh_frame_ptr_enc, &pi,
153 &eh_frame_start, NULL)) < 0)
156 /* (Optionally) read fde_count: */
157 if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
158 &addr, hdr->fde_count_enc, &pi,
159 &fde_count, NULL)) < 0)
162 if (hdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4))
167 unw_word_t eh_frame_end;
169 /* If there is no search table or it has an unsupported
170 encoding, fall back on linear search. */
171 if (hdr->table_enc == DW_EH_PE_omit)
172 Debug (4, "EH lacks search table; doing linear search\n");
174 Debug (4, "EH table has encoding 0x%x; doing linear search\n",
177 eh_frame_end = max_load_addr; /* XXX can we do better? */
179 if (hdr->fde_count_enc == DW_EH_PE_omit)
181 if (hdr->eh_frame_ptr_enc == DW_EH_PE_omit)
184 return linear_search (unw_local_addr_space, ip,
185 eh_frame_start, eh_frame_end, fde_count,
186 pi, need_unwind_info, NULL);
190 edi->di_cache.start_ip = start_ip;
191 edi->di_cache.end_ip = end_ip;
192 edi->di_cache.format = UNW_INFO_FORMAT_REMOTE_TABLE;
193 edi->di_cache.u.rti.name_ptr = 0;
194 /* two 32-bit values (ip_offset/fde_offset) per table-entry: */
195 edi->di_cache.u.rti.table_len = (fde_count * 8) / sizeof (unw_word_t);
196 edi->di_cache.u.rti.table_data = ((load_base + peh_hdr->p_vaddr)
197 + (addr - (unw_word_t) edi->ei.image
198 - peh_hdr->p_offset));
200 /* For the binary-search table in the eh_frame_hdr, data-relative
201 means relative to the start of that section... */
202 edi->di_cache.u.rti.segbase = ((load_base + peh_hdr->p_vaddr)
203 + ((unw_word_t) hdr - (unw_word_t) edi->ei.image
204 - peh_hdr->p_offset));
211 edi->di_arm.format = UNW_INFO_FORMAT_ARM_EXIDX;
212 edi->di_arm.start_ip = start_ip;
213 edi->di_arm.end_ip = end_ip;
214 edi->di_arm.u.rti.name_ptr = (unw_word_t) path;
215 edi->di_arm.u.rti.table_data = load_base + parm_exidx->p_vaddr;
216 edi->di_arm.u.rti.table_len = parm_exidx->p_memsz;
221 #ifdef CONFIG_DEBUG_FRAME
222 /* Try .debug_frame. */
223 found = dwarf_find_debug_frame (found, &edi->di_debug, ip, load_base, path,