src/libs/libunwind/dwarf/Gfind_unwind_table.c

   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
  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 "dwarf-eh.h"
  34 #include "dwarf_i.h"
  35
  36 int
  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,
  39                          unw_word_t ip)
  40 {
  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;
  47   unw_accessors_t *a;
  48   Elf_W(Ehdr) *ehdr;
  49 #if UNW_TARGET_ARM
  50   const Elf_W(Phdr) *parm_exidx = NULL;
  51 #endif
  52   int i, ret, found = 0;
  53
  54   /* XXX: Much of this code is Linux/LSB-specific.  */
  55
  56   if (!elf_w(valid_object) (&edi->ei))
  57     return -UNW_ENOINFO;
  58
  59   ehdr = edi->ei.image;
  60   phdr = (Elf_W(Phdr) *) ((char *) edi->ei.image + ehdr->e_phoff);
  61
  62   for (i = 0; i < ehdr->e_phnum; ++i)
  63     {
  64       switch (phdr[i].p_type)
  65         {
  66         case PT_LOAD:
  67           if (phdr[i].p_vaddr < start_ip)
  68             start_ip = phdr[i].p_vaddr;
  69
  70           if (phdr[i].p_vaddr + phdr[i].p_memsz > end_ip)
  71             end_ip = phdr[i].p_vaddr + phdr[i].p_memsz;
  72
  73           if (phdr[i].p_offset == mapoff)
  74             ptxt = phdr + i;
  75           if ((uintptr_t) edi->ei.image + phdr->p_filesz > max_load_addr)
  76             max_load_addr = (uintptr_t) edi->ei.image + phdr->p_filesz;
  77           break;
  78
  79         case PT_GNU_EH_FRAME:
  80           peh_hdr = phdr + i;
  81           break;
  82
  83         case PT_DYNAMIC:
  84           pdyn = phdr + i;
  85           break;
  86
  87 #if UNW_TARGET_ARM
  88         case PT_ARM_EXIDX:
  89           parm_exidx = phdr + i;
  90           break;
  91 #endif
  92
  93         default:
  94           break;
  95         }
  96     }
  97
  98   if (!ptxt)
  99     return 0;
 100
 101   load_base = segbase - ptxt->p_vaddr;
 102   start_ip += load_base;
 103   end_ip += load_base;
 104
 105   if (peh_hdr)
 106     {
 107       if (pdyn)
 108         {
 109           /* For dynamicly linked executables and shared libraries,
 110              DT_PLTGOT is the value that data-relative addresses are
 111              relative to for that object.  We call this the "gp".  */
 112                 Elf_W(Dyn) *dyn = (Elf_W(Dyn) *)(pdyn->p_offset
 113                                                  + (char *) edi->ei.image);
 114           for (; dyn->d_tag != DT_NULL; ++dyn)
 115             if (dyn->d_tag == DT_PLTGOT)
 116               {
 117                 /* Assume that _DYNAMIC is writable and GLIBC has
 118                    relocated it (true for x86 at least).  */
 119                 edi->di_cache.gp = dyn->d_un.d_ptr;
 120                 break;
 121               }
 122         }
 123       else
 124         /* Otherwise this is a static executable with no _DYNAMIC.  Assume
 125            that data-relative addresses are relative to 0, i.e.,
 126            absolute.  */
 127         edi->di_cache.gp = 0;
 128
 129       hdr = (struct dwarf_eh_frame_hdr *) (peh_hdr->p_offset
 130                                            + (char *) edi->ei.image);
 131       if (hdr->version != DW_EH_VERSION)
 132         {
 133           Debug (1, "table `%s' has unexpected version %d\n",
 134                  path, hdr->version);
 135           return -UNW_ENOINFO;
 136         }
 137
 138       a = unw_get_accessors (unw_local_addr_space);
 139       addr = (unw_word_t) (hdr + 1);
 140
 141       /* (Optionally) read eh_frame_ptr: */
 142       if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
 143                                              &addr, hdr->eh_frame_ptr_enc, edi->di_cache.gp, 0,
 144                                              &eh_frame_start, NULL)) < 0)
 145         return -UNW_ENOINFO;
 146
 147       /* (Optionally) read fde_count: */
 148       if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
 149                                              &addr, hdr->fde_count_enc, edi->di_cache.gp, 0,
 150                                              &fde_count, NULL)) < 0)
 151         return -UNW_ENOINFO;
 152
 153       if (hdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4))
 154         {
 155     #if 1
 156           abort ();
 157     #else
 158           unw_word_t eh_frame_end;
 159
 160           /* If there is no search table or it has an unsupported
 161              encoding, fall back on linear search.  */
 162           if (hdr->table_enc == DW_EH_PE_omit)
 163             Debug (4, "EH lacks search table; doing linear search\n");
 164           else
 165             Debug (4, "EH table has encoding 0x%x; doing linear search\n",
 166                    hdr->table_enc);
 167
 168           eh_frame_end = max_load_addr; /* XXX can we do better? */
 169
 170           if (hdr->fde_count_enc == DW_EH_PE_omit)
 171             fde_count = ~0UL;
 172           if (hdr->eh_frame_ptr_enc == DW_EH_PE_omit)
 173             abort ();
 174
 175           return linear_search (unw_local_addr_space, ip,
 176                                 eh_frame_start, eh_frame_end, fde_count,
 177                                 pi, need_unwind_info, NULL);
 178     #endif
 179         }
 180
 181       edi->di_cache.start_ip = start_ip;
 182       edi->di_cache.end_ip = end_ip;
 183       edi->di_cache.format = UNW_INFO_FORMAT_REMOTE_TABLE;
 184       edi->di_cache.u.rti.name_ptr = 0;
 185       /* two 32-bit values (ip_offset/fde_offset) per table-entry: */
 186       edi->di_cache.u.rti.table_len = (fde_count * 8) / sizeof (unw_word_t);
 187       edi->di_cache.u.rti.table_data = ((load_base + peh_hdr->p_vaddr)
 188                                        + (addr - (unw_word_t) edi->ei.image
 189                                           - peh_hdr->p_offset));
 190
 191       /* For the binary-search table in the eh_frame_hdr, data-relative
 192          means relative to the start of that section... */
 193       edi->di_cache.u.rti.segbase = ((load_base + peh_hdr->p_vaddr)
 194                                     + ((unw_word_t) hdr - (unw_word_t) edi->ei.image
 195                                        - peh_hdr->p_offset));
 196       found = 1;
 197     }
 198
 199 #if UNW_TARGET_ARM
 200   if (parm_exidx)
 201     {
 202       edi->di_arm.format = UNW_INFO_FORMAT_ARM_EXIDX;
 203       edi->di_arm.start_ip = start_ip;
 204       edi->di_arm.end_ip = end_ip;
 205       edi->di_arm.u.rti.name_ptr = (unw_word_t) path;
 206       edi->di_arm.u.rti.table_data = load_base + parm_exidx->p_vaddr;
 207       edi->di_arm.u.rti.table_len = parm_exidx->p_memsz;
 208       found = 1;
 209     }
 210 #endif
 211
 212 #ifdef CONFIG_DEBUG_FRAME
 213   /* Try .debug_frame. */
 214   found = dwarf_find_debug_frame (found, &edi->di_debug, ip, load_base, path,
 215                                   start_ip, end_ip);
 216 #endif
 217
 218   return found;
 219 }