src/libs/libunwind/ia64/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 #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
  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
  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 }