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"
36 #define to_unw_word(p) ((unw_word_t) (uintptr_t) (p))
39 dwarf_find_unwind_table (struct elf_dyn_info *edi, unw_addr_space_t as,
40 char *path, unw_word_t segbase, unw_word_t mapoff,
43 Elf_W(Phdr) *phdr, *ptxt = NULL, *peh_hdr = NULL, *pdyn = NULL;
44 unw_word_t addr, eh_frame_start, fde_count, load_base;
45 unw_word_t max_load_addr = 0;
46 unw_word_t start_ip = to_unw_word (-1);
47 unw_word_t end_ip = 0;
48 struct dwarf_eh_frame_hdr *hdr;
53 const Elf_W(Phdr) *parm_exidx = NULL;
55 int i, ret, found = 0;
57 /* XXX: Much of this code is Linux/LSB-specific. */
59 if (!elf_w(valid_object) (&edi->ei))
63 phdr = (Elf_W(Phdr) *) ((char *) edi->ei.image + ehdr->e_phoff);
65 for (i = 0; i < ehdr->e_phnum; ++i)
67 switch (phdr[i].p_type)
70 if (phdr[i].p_vaddr < start_ip)
71 start_ip = phdr[i].p_vaddr;
73 if (phdr[i].p_vaddr + phdr[i].p_memsz > end_ip)
74 end_ip = phdr[i].p_vaddr + phdr[i].p_memsz;
76 if (phdr[i].p_offset == mapoff)
78 if ((uintptr_t) edi->ei.image + phdr->p_filesz > max_load_addr)
79 max_load_addr = (uintptr_t) edi->ei.image + phdr->p_filesz;
92 parm_exidx = phdr + i;
104 load_base = segbase - ptxt->p_vaddr;
105 start_ip += load_base;
112 /* For dynamicly linked executables and shared libraries,
113 DT_PLTGOT is the value that data-relative addresses are
114 relative to for that object. We call this the "gp". */
115 Elf_W(Dyn) *dyn = (Elf_W(Dyn) *)(pdyn->p_offset
116 + (char *) edi->ei.image);
117 for (; dyn->d_tag != DT_NULL; ++dyn)
118 if (dyn->d_tag == DT_PLTGOT)
120 /* Assume that _DYNAMIC is writable and GLIBC has
121 relocated it (true for x86 at least). */
122 edi->di_cache.gp = dyn->d_un.d_ptr;
127 /* Otherwise this is a static executable with no _DYNAMIC. Assume
128 that data-relative addresses are relative to 0, i.e.,
130 edi->di_cache.gp = 0;
132 hdr = (struct dwarf_eh_frame_hdr *) (peh_hdr->p_offset
133 + (char *) edi->ei.image);
134 if (hdr->version != DW_EH_VERSION)
136 Debug (1, "table `%s' has unexpected version %d\n",
141 a = unw_get_accessors_int (unw_local_addr_space);
142 addr = to_unw_word (&hdr->eh_frame);
144 /* Fill in a dummy proc_info structure. We just need to fill in
145 enough to ensure that dwarf_read_encoded_pointer() can do it's
146 job. Since we don't have a procedure-context at this point, all
147 we have to do is fill in the global-pointer. */
148 memset (&pi, 0, sizeof (pi));
149 pi.gp = edi->di_cache.gp;
151 /* (Optionally) read eh_frame_ptr: */
152 if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
153 &addr, hdr->eh_frame_ptr_enc, &pi,
154 &eh_frame_start, NULL)) < 0)
157 /* (Optionally) read fde_count: */
158 if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
159 &addr, hdr->fde_count_enc, &pi,
160 &fde_count, NULL)) < 0)
163 if (hdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4))
168 unw_word_t eh_frame_end;
170 /* If there is no search table or it has an unsupported
171 encoding, fall back on linear search. */
172 if (hdr->table_enc == DW_EH_PE_omit)
173 Debug (4, "EH lacks search table; doing linear search\n");
175 Debug (4, "EH table has encoding 0x%x; doing linear search\n",
178 eh_frame_end = max_load_addr; /* XXX can we do better? */
180 if (hdr->fde_count_enc == DW_EH_PE_omit)
182 if (hdr->eh_frame_ptr_enc == DW_EH_PE_omit)
185 return linear_search (unw_local_addr_space, ip,
186 eh_frame_start, eh_frame_end, fde_count,
187 pi, need_unwind_info, NULL);
191 edi->di_cache.start_ip = start_ip;
192 edi->di_cache.end_ip = end_ip;
193 edi->di_cache.format = UNW_INFO_FORMAT_REMOTE_TABLE;
194 edi->di_cache.u.rti.name_ptr = 0;
195 /* two 32-bit values (ip_offset/fde_offset) per table-entry: */
196 edi->di_cache.u.rti.table_len = (fde_count * 8) / sizeof (unw_word_t);
197 edi->di_cache.u.rti.table_data = ((load_base + peh_hdr->p_vaddr)
198 + (addr - to_unw_word (edi->ei.image)
199 - peh_hdr->p_offset));
201 /* For the binary-search table in the eh_frame_hdr, data-relative
202 means relative to the start of that section... */
203 edi->di_cache.u.rti.segbase = ((load_base + peh_hdr->p_vaddr)
204 + (to_unw_word (hdr) -
205 to_unw_word (edi->ei.image)
206 - peh_hdr->p_offset));
213 edi->di_arm.format = UNW_INFO_FORMAT_ARM_EXIDX;
214 edi->di_arm.start_ip = start_ip;
215 edi->di_arm.end_ip = end_ip;
216 edi->di_arm.u.rti.name_ptr = to_unw_word (path);
217 edi->di_arm.u.rti.table_data = load_base + parm_exidx->p_vaddr;
218 edi->di_arm.u.rti.table_len = parm_exidx->p_memsz;
223 #ifdef CONFIG_DEBUG_FRAME
224 /* Try .debug_frame. */
225 found = dwarf_find_debug_frame (found, &edi->di_debug, ip, load_base, path,