/* Copyright (C) 2001-2018 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;

  const ElfW(Phdr) *p_dynamic __attribute__ ((unused));

  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