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/* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009 Free Software Foundation, Inc.

   Contributed by Jakub Jelinek <jakub@redhat.com>.

   This file is part of GCC.

   GCC is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3, or (at your option)

   any later version.

   GCC 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 General Public License for more details.

   Under Section 7 of GPL version 3, you are granted additional

   permissions described in the GCC Runtime Library Exception, version

   3.1, as published by the Free Software Foundation.

   You should have received a copy of the GNU General Public License and

   a copy of the GCC Runtime Library Exception along with this program;

   see the files COPYING3 and COPYING.RUNTIME respectively.  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.  */

#ifndef _GNU_SOURCE

#define _GNU_SOURCE 1

#endif

#include "tconfig.h"

#include "tsystem.h"

#ifndef inhibit_libc

#include <link.h>

#endif

#include "coretypes.h"

#include "tm.h"

#include "dwarf2.h"

#include "unwind.h"

#define NO_BASE_OF_ENCODED_VALUE

#include "unwind-pe.h"

#include "unwind-dw2-fde.h"

#include "unwind-compat.h"

#include "gthr.h"

#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \

    && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \

        || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))

# define USE_PT_GNU_EH_FRAME

#endif

#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \

    && defined(__FreeBSD__) && __FreeBSD__ >= 7

# define ElfW __ElfN

# define USE_PT_GNU_EH_FRAME

#endif

#if defined(USE_PT_GNU_EH_FRAME)

#ifndef __RELOC_POINTER

# define __RELOC_POINTER(ptr, base) ((ptr) + (base))

#endif

static const fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases);

#define _Unwind_Find_FDE _Unwind_Find_registered_FDE

#include "unwind-dw2-fde.c"

#undef _Unwind_Find_FDE

#ifndef PT_GNU_EH_FRAME

#define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550)

#endif

struct unw_eh_callback_data

{

  _Unwind_Ptr pc;

  void *tbase;

  void *dbase;

  void *func;

  const fde *ret;

  int check_cache;

};

struct unw_eh_frame_hdr

{

  unsigned char version;

  unsigned char eh_frame_ptr_enc;

  unsigned char fde_count_enc;

  unsigned char table_enc;

};

#define FRAME_HDR_CACHE_SIZE 8

static struct frame_hdr_cache_element

{

  _Unwind_Ptr pc_low;

  _Unwind_Ptr pc_high;

  _Unwind_Ptr load_base;

  const ElfW(Phdr) *p_eh_frame_hdr;

  const ElfW(Phdr) *p_dynamic;

  struct frame_hdr_cache_element *link;

} frame_hdr_cache[FRAME_HDR_CACHE_SIZE];

static struct frame_hdr_cache_element *frame_hdr_cache_head;

/* Like base_of_encoded_value, but take the base from a struct

   unw_eh_callback_data 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;

    default:

      gcc_unreachable ();

    }

}

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;

#ifdef __FRV_FDPIC__

  struct elf32_fdpic_loadaddr load_base;

#else

  _Unwind_Ptr load_base;

#endif

  const unsigned char *p;

  const struct unw_eh_frame_hdr *hdr;

  _Unwind_Ptr eh_frame;

  struct object ob;

  _Unwind_Ptr pc_low = 0, pc_high = 0;

  struct ext_dl_phdr_info

    {

      ElfW(Addr) dlpi_addr;

      const char *dlpi_name;

      const ElfW(Phdr) *dlpi_phdr;

      ElfW(Half) dlpi_phnum;

      unsigned long long int dlpi_adds;

      unsigned long long int dlpi_subs;

    };

  match = 0;

  phdr = info->dlpi_phdr;

  load_base = info->dlpi_addr;

  p_eh_frame_hdr = NULL;

  p_dynamic = NULL;

  struct frame_hdr_cache_element *prev_cache_entry = NULL,

    *last_cache_entry = NULL;

  if (data->check_cache && size >= sizeof (struct ext_dl_phdr_info))

    {

      static unsigned long long adds = -1ULL, subs;

      struct ext_dl_phdr_info *einfo = (struct ext_dl_phdr_info *) info;

      /* We use a least recently used cache replacement policy.  Also,

         the most recently used cache entries are placed at the head

         of the search chain.  */

      if (einfo->dlpi_adds == adds && einfo->dlpi_subs == subs)

        {

          /* Find data->pc in shared library cache.

             Set load_base, p_eh_frame_hdr and p_dynamic

             plus match from the cache and goto

             "Read .eh_frame_hdr header." below.  */

          struct frame_hdr_cache_element *cache_entry;

          for (cache_entry = frame_hdr_cache_head;

               cache_entry;

               cache_entry = cache_entry->link)

            {

              if (data->pc >= cache_entry->pc_low

                  && data->pc < cache_entry->pc_high)

                {

                  load_base = cache_entry->load_base;

                  p_eh_frame_hdr = cache_entry->p_eh_frame_hdr;

                  p_dynamic = cache_entry->p_dynamic;

                  /* And move the entry we're using to the head.  */

                  if (cache_entry != frame_hdr_cache_head)

                    {

                      prev_cache_entry->link = cache_entry->link;

                      cache_entry->link = frame_hdr_cache_head;

                      frame_hdr_cache_head = cache_entry;

                    }

                  goto found;

                }

              last_cache_entry = cache_entry;

              /* Exit early if we found an unused entry.  */

              if ((cache_entry->pc_low | cache_entry->pc_high) == 0)

                break;

              if (cache_entry->link != NULL)

                prev_cache_entry = cache_entry;

            }

        }

      else

        {

          adds = einfo->dlpi_adds;

          subs = einfo->dlpi_subs;

          /* Initialize the cache.  Create a chain of cache entries,

             with the final one terminated by a NULL link.  */

          int i;

          for (i = 0; i < FRAME_HDR_CACHE_SIZE; i++)

            {

              frame_hdr_cache[i].pc_low = 0;

              frame_hdr_cache[i].pc_high = 0;

              frame_hdr_cache[i].link = &frame_hdr_cache[i+1];

            }

          frame_hdr_cache[i-1].link = NULL;

          frame_hdr_cache_head = &frame_hdr_cache[0];

          data->check_cache = 0;

        }

    }

  /* 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;

  /* 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 = (_Unwind_Ptr)

            __RELOC_POINTER (phdr->p_vaddr, load_base);

          if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)

            {

              match = 1;

              pc_low = vaddr;

              pc_high =  vaddr + phdr->p_memsz;

            }

        }

      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)

    return 0;

  if (size >= sizeof (struct ext_dl_phdr_info))

    {

      /* Move the cache entry we're about to overwrite to the head of

         the list.  If either last_cache_entry or prev_cache_entry are

         NULL, that cache entry is already at the head.  */

      if (last_cache_entry != NULL && prev_cache_entry != NULL)

        {

          prev_cache_entry->link = last_cache_entry->link;

          last_cache_entry->link = frame_hdr_cache_head;

          frame_hdr_cache_head = last_cache_entry;

        }

      frame_hdr_cache_head->load_base = load_base;

      frame_hdr_cache_head->p_eh_frame_hdr = p_eh_frame_hdr;

      frame_hdr_cache_head->p_dynamic = p_dynamic;

      frame_hdr_cache_head->pc_low = pc_low;

      frame_hdr_cache_head->pc_high = pc_high;

    }

 found:

  if (!p_eh_frame_hdr)

    return 0;

  /* Read .eh_frame_hdr header.  */

  hdr = (const struct unw_eh_frame_hdr *)

    __RELOC_POINTER (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 dynamically linked executables and shared libraries,

         DT_PLTGOT is the gp value for that object.  */

      ElfW(Dyn) *dyn = (ElfW(Dyn) *)

        __RELOC_POINTER (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;

          }

    }

# elif defined __FRV_FDPIC__ && defined __linux__

  data->dbase = load_base.got_value;

# else

#  error What is DW_EH_PE_datarel base on this platform?

# endif

#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;

                }

              gcc_assert (lo < hi);

            }

          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)

    {

      _Unwind_Ptr func;

      unsigned int encoding = get_fde_encoding (data->ret);

      read_encoded_value_with_base (encoding,

                                    base_from_cb_data (encoding, data),

                                    data->ret->pc_begin, &func);

      data->func = (void *) func;

    }

  return 1;

}

const fde *

_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)

{

  struct unw_eh_callback_data data;

  const 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;

  data.check_cache = 1;

  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;

}

#else

/* Prevent multiple include of header files.  */

#define _Unwind_Find_FDE _Unwind_Find_FDE

#include "unwind-dw2-fde.c"

#endif

#if defined (USE_GAS_SYMVER) && defined (SHARED) && defined (USE_LIBUNWIND_EXCEPTIONS)

alias (_Unwind_Find_FDE);

#endif