xref: /freebsd-11-stable/contrib/gcc/config/ia64/fde-glibc.c

/* Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
   Contributed by Richard Henderson <rth@cygnus.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 2, 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.

   You should have received a copy of the GNU General Public License
   along with GCC; see the file COPYING.  If not, write to
   the Free Software Foundation, 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.  */

/* As a special exception, if you link this library with other files,
   some of which are compiled with GCC, to produce an executable,
   this library does not by itself cause the resulting executable
   to be covered by the GNU General Public License.
   This exception does not however invalidate any other reasons why
   the executable file might be covered by the GNU General Public License.  */

/* Locate the FDE entry for a given address, using glibc ld.so routines
   to avoid register/deregister calls at DSO load/unload.  */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif
#include "config.h"
#include <stddef.h>
#include <stdlib.h>
#include <link.h>
#include "unwind-ia64.h"

#if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 2) \
    || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && !defined(DT_CONFIG))
# error You need GLIBC 2.2.4 or later on IA-64 Linux
#endif

struct unw_ia64_callback_data
{
  Elf64_Addr pc;
  unsigned long *segment_base;
  unsigned long *gp;
  struct unw_table_entry *ret;
};

static int
_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
{
  struct unw_ia64_callback_data *data = (struct unw_ia64_callback_data *) ptr;
  const Elf64_Phdr *phdr, *p_unwind, *p_dynamic;
  long n, match;
  Elf64_Addr load_base, seg_base;
  struct unw_table_entry *f_base, *f;
  size_t lo, hi;

  /* 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_unwind = NULL;
  p_dynamic = NULL;
  seg_base = ~(Elf64_Addr) 0;

  /* See if PC falls into one of the loaded segments.  Find the unwind
     segment at the same time.  */
  for (n = info->dlpi_phnum; --n >= 0; phdr++)
    {
      if (phdr->p_type == PT_LOAD)
	{
	  Elf64_Addr vaddr = phdr->p_vaddr + load_base;
	  if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
	    match = 1;
	  if (vaddr < seg_base)
	    seg_base = vaddr;
	}
      else if (phdr->p_type == PT_IA_64_UNWIND)
	p_unwind = phdr;
      else if (phdr->p_type == PT_DYNAMIC)
	p_dynamic = phdr;
    }
  if (!match || !p_unwind)
    return 0;

  /* Search for the FDE within the unwind segment.  */

  f_base = (struct unw_table_entry *) (p_unwind->p_vaddr + load_base);
  lo = 0;
  hi = p_unwind->p_memsz / sizeof (struct unw_table_entry);

  while (lo < hi)
    {
      size_t mid = (lo + hi) / 2;

      f = f_base + mid;
      if (data->pc < f->start_offset + seg_base)
	hi = mid;
      else if (data->pc >= f->end_offset + seg_base)
	lo = mid + 1;
      else
        goto found;
    }
  /* No need to search for further libraries when we know pc is contained
     in this library.  */
  return 1;

 found:
  *data->segment_base = seg_base;
  *data->gp = 0;
  data->ret = f;

  if (p_dynamic)
    {
      /* For dynamically linked executables and shared libraries,
	 DT_PLTGOT is the gp value for that object.  */
      Elf64_Dyn *dyn = (Elf64_Dyn *)(p_dynamic->p_vaddr + load_base);
      for (; dyn->d_tag != DT_NULL ; dyn++)
	if (dyn->d_tag == DT_PLTGOT)
	  {
	    /* On IA-64, _DYNAMIC is writable and GLIBC has relocated it.  */
	    *data->gp = dyn->d_un.d_ptr;
	    break;
	  }
    }
  else
    {
      /* Otherwise this is a static executable with no _DYNAMIC.
	 The gp is constant program-wide.  */
      register unsigned long gp __asm__("gp");
      *data->gp = gp;
    }

  return 1;
}

/* Return a pointer to the unwind table entry for the function
   containing PC.  */

struct unw_table_entry *
_Unwind_FindTableEntry (void *pc, unsigned long *segment_base,
                        unsigned long *gp)
{
  struct unw_ia64_callback_data data;

  data.pc = (Elf64_Addr) pc;
  data.segment_base = segment_base;
  data.gp = gp;
  data.ret = NULL;

  if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
    return NULL;

  return data.ret;
}