text: /* Copyright (C) 2001, 2002, 2007 Free Software Foundation, Inc.
     Contributed by Jakub Jelinek <jakub@redhat.com>.
  
     This file is part of the GNU C Library.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  /* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
     segment and dl_iterate_phdr to avoid register/deregister calls at
     DSO load/unload.  */
  
  #ifdef _LIBC
  # include <shlib-compat.h>
  #endif
  
  #if !defined _LIBC || SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2_5)
  
  #include <link.h>
  #include <stddef.h>
  
  #define _Unwind_Find_FDE _Unwind_Find_registered_FDE
  
  #include <unwind-dw2-fde.c>
  
  #undef _Unwind_Find_FDE
  
  extern fde * _Unwind_Find_registered_FDE (void *pc,
  					  struct dwarf_eh_bases *bases);
  extern fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
  
  struct unw_eh_callback_data
  {
    _Unwind_Ptr pc;
    void *tbase;
    void *dbase;
    void *func;
    fde *ret;
  };
  
  struct unw_eh_frame_hdr
  {
    unsigned char version;
    unsigned char eh_frame_ptr_enc;
    unsigned char fde_count_enc;
    unsigned char table_enc;
  };
  
  /* Like base_of_encoded_value, but take the base from a struct object
     instead of an _Unwind_Context.  */
  
  static _Unwind_Ptr
  base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
  {
    if (encoding == DW_EH_PE_omit)
      return 0;
  
    switch (encoding & 0x70)
      {
      case DW_EH_PE_absptr:
      case DW_EH_PE_pcrel:
      case DW_EH_PE_aligned:
        return 0;
  
      case DW_EH_PE_textrel:
        return (_Unwind_Ptr) data->tbase;
      case DW_EH_PE_datarel:
        return (_Unwind_Ptr) data->dbase;
      }
    abort ();
  }
  
  static int
  _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
  {
    struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
    const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
    long n, match;
    _Unwind_Ptr load_base;
    const unsigned char *p;
    const struct unw_eh_frame_hdr *hdr;
    _Unwind_Ptr eh_frame;
    struct object ob;
  
    /* Make sure struct dl_phdr_info is at least as big as we need.  */
    if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
  	     + sizeof (info->dlpi_phnum))
      return -1;
  
    match = 0;
    phdr = info->dlpi_phdr;
    load_base = info->dlpi_addr;
    p_eh_frame_hdr = NULL;
    p_dynamic = NULL;
  
    /* See if PC falls into one of the loaded segments.  Find the eh_frame
       segment at the same time.  */
    for (n = info->dlpi_phnum; --n >= 0; phdr++)
      {
        if (phdr->p_type == PT_LOAD)
  	{
  	  _Unwind_Ptr vaddr = phdr->p_vaddr + load_base;
  	  if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
  	    match = 1;
  	}
        else if (phdr->p_type == PT_GNU_EH_FRAME)
  	p_eh_frame_hdr = phdr;
        else if (phdr->p_type == PT_DYNAMIC)
  	p_dynamic = phdr;
      }
    if (!match || !p_eh_frame_hdr)
      return 0;
  
    /* Read .eh_frame_hdr header.  */
    hdr = (const struct unw_eh_frame_hdr *)
  	(p_eh_frame_hdr->p_vaddr + load_base);
    if (hdr->version != 1)
      return 1;
  
  #ifdef CRT_GET_RFIB_DATA
  # ifdef __i386__
    data->dbase = NULL;
    if (p_dynamic)
      {
        /* For dynamicly linked executables and shared libraries,
  	 DT_PLTGOT is the gp value for that object.  */
        ElfW(Dyn) *dyn = (ElfW(Dyn) *)(p_dynamic->p_vaddr + load_base);
        for (; dyn->d_tag != DT_NULL ; dyn++)
  	if (dyn->d_tag == DT_PLTGOT)
  	  {
  	    /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it.  */
  	    data->dbase = (void *) dyn->d_un.d_ptr;
  	    break;
  	  }
      }
  # else
  #  error What is DW_EH_PE_datarel base on this platform?
  # endif
  #endif
  #ifdef CRT_GET_RFIB_TEXT
  # error What is DW_EH_PE_textrel base on this platform?
  #endif
  
    p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
  				    base_from_cb_data (hdr->eh_frame_ptr_enc,
  						       data),
  				    (const unsigned char *) (hdr + 1),
  				    &eh_frame);
  
    /* We require here specific table encoding to speed things up.
       Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
       as base, not the processor specific DW_EH_PE_datarel.  */
    if (hdr->fde_count_enc != DW_EH_PE_omit
        && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
      {
        _Unwind_Ptr fde_count;
  
        p = read_encoded_value_with_base (hdr->fde_count_enc,
  					base_from_cb_data (hdr->fde_count_enc,
  							   data),
  					p, &fde_count);
        /* Shouldn't happen.  */
        if (fde_count == 0)
  	return 1;
        if ((((_Unwind_Ptr) p) & 3) == 0)
  	{
  	  struct fde_table {
  	    signed initial_loc __attribute__ ((mode (SI)));
  	    signed fde __attribute__ ((mode (SI)));
  	  };
  	  const struct fde_table *table = (const struct fde_table *) p;
  	  size_t lo, hi, mid;
  	  _Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
  	  fde *f;
  	  unsigned int f_enc, f_enc_size;
  	  _Unwind_Ptr range;
  
  	  mid = fde_count - 1;
  	  if (data->pc < table[0].initial_loc + data_base)
  	    return 1;
  	  else if (data->pc < table[mid].initial_loc + data_base)
  	    {
  	      lo = 0;
  	      hi = mid;
  
  	      while (lo < hi)
  		{
  		  mid = (lo + hi) / 2;
  		  if (data->pc < table[mid].initial_loc + data_base)
  		    hi = mid;
  		  else if (data->pc >= table[mid + 1].initial_loc + data_base)
  		    lo = mid + 1;
  		  else
  		    break;
  		}
  
  	      if (lo >= hi)
  		__gxx_abort ();
  	    }
  
  	  f = (fde *) (table[mid].fde + data_base);
  	  f_enc = get_fde_encoding (f);
  	  f_enc_size = size_of_encoded_value (f_enc);
  	  read_encoded_value_with_base (f_enc & 0x0f, 0,
  					&f->pc_begin[f_enc_size], &range);
  	  if (data->pc < table[mid].initial_loc + data_base + range)
  	    data->ret = f;
  	  data->func = (void *) (table[mid].initial_loc + data_base);
  	  return 1;
  	}
      }
  
    /* We have no sorted search table, so need to go the slow way.
       As soon as GLIBC will provide API so to notify that a library has been
       removed, we could cache this (and thus use search_object).  */
    ob.pc_begin = NULL;
    ob.tbase = data->tbase;
    ob.dbase = data->dbase;
    ob.u.single = (fde *) eh_frame;
    ob.s.i = 0;
    ob.s.b.mixed_encoding = 1;  /* Need to assume worst case.  */
    data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
    if (data->ret != NULL)
      {
        unsigned int encoding = get_fde_encoding (data->ret);
        _Unwind_Ptr func;
        read_encoded_value_with_base (encoding,
  				    base_from_cb_data (encoding, data),
  				    data->ret->pc_begin, &func);
        data->func = (void *) func;
      }
    return 1;
  }
  
  # ifdef _LIBC
  # define dl_iterate_phdr __dl_iterate_phdr
  # endif
  
  fde *
  _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
  {
    struct unw_eh_callback_data data;
    fde *ret;
  
    ret = _Unwind_Find_registered_FDE (pc, bases);
    if (ret != NULL)
      return ret;
  
    data.pc = (_Unwind_Ptr) pc;
    data.tbase = NULL;
    data.dbase = NULL;
    data.func = NULL;
    data.ret = NULL;
  
    if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
      return NULL;
  
    if (data.ret)
      {
        bases->tbase = data.tbase;
        bases->dbase = data.dbase;
        bases->func = data.func;
      }
    return data.ret;
  }
  
  #endif
  