/* libunwind - a platform-independent unwind library
   Copyright (C) 2003-2004 Hewlett-Packard Co
        Contributed by David Mosberger-Tang <davidm@hpl.hp.com>

This file is part of libunwind.

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */

#include <fcntl.h>
#include <string.h>
#include <unistd.h>

#include <sys/mman.h>

#include "libunwind_i.h"
#include "dwarf-eh.h"
#include "dwarf_i.h"

#define to_unw_word(p) ((unw_word_t) (uintptr_t) (p))

int
dwarf_find_unwind_table (struct elf_dyn_info *edi,
						 unw_addr_space_t     as UNUSED,
                         const char          *path UNUSED,
                         unw_word_t           segbase,
                         unw_word_t           mapoff,
                         unw_word_t           ip UNUSED)
{
  Elf_W(Phdr) *phdr, *ptxt = NULL, *peh_hdr = NULL, *pdyn = NULL;
  unw_word_t addr, eh_frame_start, fde_count, loadoff, load_base;
  unw_word_t max_load_addr = 0;
  unw_word_t start_ip = to_unw_word (-1);
  unw_word_t end_ip = 0;
  struct dwarf_eh_frame_hdr *hdr;
  unw_proc_info_t pi;
  unw_accessors_t *a;
  Elf_W(Ehdr) *ehdr;
#if UNW_TARGET_ARM
  const Elf_W(Phdr) *param_exidx = NULL;
#endif
  int i, ret, found = 0;

  /* XXX: Much of this code is Linux/LSB-specific.  */

  if (!elf_w(valid_object) (&edi->ei))
    return -UNW_ENOINFO;

  ehdr = edi->ei.image;
  phdr = (Elf_W(Phdr) *) ((char *) edi->ei.image + ehdr->e_phoff);

  for (i = 0; i < ehdr->e_phnum; ++i)
    {
      switch (phdr[i].p_type)
        {
        case PT_LOAD:
          if (phdr[i].p_vaddr < start_ip)
            start_ip = phdr[i].p_vaddr;

          if (phdr[i].p_vaddr + phdr[i].p_memsz > end_ip)
            end_ip = phdr[i].p_vaddr + phdr[i].p_memsz;

          /* Find the PT_LOAD segment that corresponds to the memory mapping.
             When there are multiple executable segments, we need to match
             the one whose file offset corresponds to mapoff. */
          if ((phdr[i].p_flags & PF_X) == PF_X) {
            if (ptxt == NULL || phdr[i].p_offset == mapoff) {
              ptxt = phdr + i;
            } else {
              Debug(5, "skipping PT_LOAD segment at p_offset=0x%lx (does not match mapoff=0x%lx)\n",
                    (long)phdr[i].p_offset, (long)mapoff);
            }
          }
          if ((uintptr_t) edi->ei.image + phdr->p_filesz > max_load_addr)
            max_load_addr = (uintptr_t) edi->ei.image + phdr->p_filesz;
          break;

        case PT_GNU_EH_FRAME:
#if defined __sun
        case PT_SUNW_UNWIND:
#endif
          peh_hdr = phdr + i;
          break;

        case PT_DYNAMIC:
          pdyn = phdr + i;
          break;

#if UNW_TARGET_ARM
        case PT_ARM_EXIDX:
          param_exidx = phdr + i;
          break;
#endif

        default:
          break;
        }
    }

  if (!ptxt)
    return 0;

  loadoff = mapoff + (ptxt->p_vaddr - ptxt->p_offset);
  load_base = segbase - loadoff;
  start_ip += load_base;
  end_ip += load_base;

  if (peh_hdr)
    {
      Elf_W(Dyn) *dyn = (Elf_W(Dyn) *)elf_w (get_program_segment) (&edi->ei, pdyn, NULL);
      if (dyn)
        {
          /* For dynamically linked executables and shared libraries,
             DT_PLTGOT is the value that data-relative addresses are
             relative to for that object.  We call this the "gp".  */

          for (; dyn->d_tag != DT_NULL; ++dyn)
            if (dyn->d_tag == DT_PLTGOT)
              {
                /* Assume that _DYNAMIC is writable and GLIBC has
                   relocated it (true for x86 at least).  */
                edi->di_cache.gp = dyn->d_un.d_ptr;
                break;
              }
        }
      else
        /* Otherwise this is a static executable with no _DYNAMIC.  Assume
           that data-relative addresses are relative to 0, i.e.,
           absolute.  */
        edi->di_cache.gp = 0;

      hdr = (struct dwarf_eh_frame_hdr *) elf_w (get_program_segment) (&edi->ei, peh_hdr, NULL);
      if (!hdr)
        {
          Debug (1, "table `%s' missing\n", path);
          return -UNW_ENOINFO;
        }

      if (hdr->version != DW_EH_VERSION)
        {
          Debug (1, "table `%s' has unexpected version %d\n",
                 path, hdr->version);
          return -UNW_ENOINFO;
        }

      a = unw_get_accessors_int (unw_local_addr_space);
      addr = to_unw_word (&hdr->eh_frame);

      /* Fill in a dummy proc_info structure.  We just need to fill in
         enough to ensure that dwarf_read_encoded_pointer() can do it's
         job.  Since we don't have a procedure-context at this point, all
         we have to do is fill in the global-pointer.  */
      memset (&pi, 0, sizeof (pi));
      pi.gp = edi->di_cache.gp;

      /* (Optionally) read eh_frame_ptr: */
      if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
                                             &addr, hdr->eh_frame_ptr_enc, &pi,
                                             &eh_frame_start, NULL)) < 0)
        return -UNW_ENOINFO;

      /* (Optionally) read fde_count: */
      if ((ret = dwarf_read_encoded_pointer (unw_local_addr_space, a,
                                             &addr, hdr->fde_count_enc, &pi,
                                             &fde_count, NULL)) < 0)
        return -UNW_ENOINFO;

      /* A value of DW_EH_PE_omit indicates the binary search table is not present. */
      if (hdr->table_enc == DW_EH_PE_omit)
        return -UNW_ENOINFO;

      if (hdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4)
          && hdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata8))
        {
          Debug (4, "EH table has encoding 0x%x; cannot use binary search\n",
                 hdr->table_enc);

          /* Cannot build a binary search table for unsupported encoding;
             return 0 so the caller can fall back to other methods.  */
          return 0;
        }

      {
        int is_sdata8 = (hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata8));
        size_t entry_size = is_sdata8 ? 16 : 8;

        edi->di_cache.start_ip = start_ip;
        edi->di_cache.end_ip = end_ip;
        edi->di_cache.format = is_sdata8 ? UNW_INFO_FORMAT_REMOTE_TABLE_64
                                         : UNW_INFO_FORMAT_REMOTE_TABLE;
        edi->di_cache.u.rti.name_ptr = 0;
        edi->di_cache.u.rti.table_len = (fde_count * entry_size) / sizeof (unw_word_t);
        edi->di_cache.u.rti.table_data = ((load_base + peh_hdr->p_vaddr)
                                       + (addr - to_unw_word (edi->ei.image)
                                          - peh_hdr->p_offset));

        /* For the binary-search table in the eh_frame_hdr, data-relative
           means relative to the start of that section... */
        edi->di_cache.u.rti.segbase = ((load_base + peh_hdr->p_vaddr)
                                    + (to_unw_word (hdr) -
                                       to_unw_word (edi->ei.image)
                                       - peh_hdr->p_offset));
        found = 1;
      }
    }

#if UNW_TARGET_ARM
  if (param_exidx)
    {
      edi->di_arm.format = UNW_INFO_FORMAT_ARM_EXIDX;
      edi->di_arm.start_ip = start_ip;
      edi->di_arm.end_ip = end_ip;
      edi->di_arm.u.rti.name_ptr = to_unw_word (path);
      edi->di_arm.u.rti.table_data = load_base + param_exidx->p_vaddr;
      edi->di_arm.u.rti.table_len = param_exidx->p_memsz;
      found = 1;
    }
#endif

#ifdef CONFIG_DEBUG_FRAME
  /* Try .debug_frame. */
  found = dwarf_find_debug_frame (found, &edi->di_debug, ip, load_base, path,
                                  start_ip, end_ip);
#endif

  return found;
}
