Remove trailing white spaces.

[thirdparty/gcc.git] / gcc / unwind-dw2-fde-glibc.c

/* 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