libdwfl/dwfl_report_elf.c - platform/external/elfutils - Git at Google

 /* Report a module to libdwfl based on ELF program headers.
    Copyright (C) 2005, 2007 Red Hat, Inc.
    This file is part of Red Hat elfutils.

    Red Hat elfutils 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; version 2 of the License.

    Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

    In addition, as a special exception, Red Hat, Inc. gives You the
    additional right to link the code of Red Hat elfutils with code licensed
    under any Open Source Initiative certified open source license
    (http://www.opensource.org/licenses/index.php) which requires the
    distribution of source code with any binary distribution and to
    distribute linked combinations of the two.  Non-GPL Code permitted under
    this exception must only link to the code of Red Hat elfutils through
    those well defined interfaces identified in the file named EXCEPTION
    found in the source code files (the "Approved Interfaces").  The files
    of Non-GPL Code may instantiate templates or use macros or inline
    functions from the Approved Interfaces without causing the resulting
    work to be covered by the GNU General Public License.  Only Red Hat,
    Inc. may make changes or additions to the list of Approved Interfaces.
    Red Hat's grant of this exception is conditioned upon your not adding
    any new exceptions.  If you wish to add a new Approved Interface or
    exception, please contact Red Hat.  You must obey the GNU General Public
    License in all respects for all of the Red Hat elfutils code and other
    code used in conjunction with Red Hat elfutils except the Non-GPL Code
    covered by this exception.  If you modify this file, you may extend this
    exception to your version of the file, but you are not obligated to do
    so.  If you do not wish to provide this exception without modification,
    you must delete this exception statement from your version and license
    this file solely under the GPL without exception.

    Red Hat elfutils is an included package of the Open Invention Network.
    An included package of the Open Invention Network is a package for which
    Open Invention Network licensees cross-license their patents.  No patent
    license is granted, either expressly or impliedly, by designation as an
    included package.  Should you wish to participate in the Open Invention
    Network licensing program, please visit www.openinventionnetwork.com
    <http://www.openinventionnetwork.com>.  */

 #include "libdwflP.h"
 #include <fcntl.h>
 #include <unistd.h>


 /* We start every ET_REL module at a moderately aligned boundary.
    This keeps the low addresses easy to read compared to a layout
    starting at 0 (as when using -e).  It also makes it unlikely
    that a middle section will have a larger alignment and require
    rejiggering (see below).  */
 #define REL_MIN_ALIGN	((GElf_Xword) 0x100)

 Dwfl_Module *
 internal_function
 __libdwfl_report_elf (Dwfl *dwfl, const char *name, const char *file_name,
 		      int fd, Elf *elf, GElf_Addr base)
 {
   GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);
   if (ehdr == NULL)
     {
     elf_error:
       __libdwfl_seterrno (DWFL_E_LIBELF);
       return NULL;
     }

   GElf_Addr start = 0, end = 0, bias = 0;
   switch (ehdr->e_type)
     {
     case ET_REL:
       /* For a relocatable object, we do an arbitrary section layout.
 	 By updating the section header in place, we leave the layout
 	 information to be found by relocation.  */

       start = end = base = (base + REL_MIN_ALIGN - 1) & -REL_MIN_ALIGN;

       bool first = true;
       Elf_Scn *scn = NULL;
       while ((scn = elf_nextscn (elf, scn)) != NULL)
 	{
 	  GElf_Shdr shdr_mem;
 	  GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
 	  if (unlikely (shdr == NULL))
 	    goto elf_error;

 	  if (shdr->sh_flags & SHF_ALLOC)
 	    {
 	      const GElf_Xword align = shdr->sh_addralign ?: 1;
 	      const GElf_Addr next = (end + align - 1) & -align;
 	      if (shdr->sh_addr == 0
 		  /* Once we've started doing layout we have to do it all,
 		     unless we just layed out the first section at 0 when
 		     it already was at 0.  */
 		  || (bias == 0 && end > start && end != next))
 		{
 		  shdr->sh_addr = next;
 		  if (end == base)
 		    /* This is the first section assigned a location.
 		       Use its aligned address as the module's base.  */
 		    start = base = shdr->sh_addr;
 		  else if (unlikely (base & (align - 1)))
 		    {
 		      /* If BASE has less than the maximum alignment of
 			 any section, we eat more than the optimal amount
 			 of padding and so make the module's apparent
 			 size come out larger than it would when placed
 			 at zero.  So reset the layout with a better base.  */

 		      start = end = base = (base + align - 1) & -align;
 		      Elf_Scn *prev_scn = NULL;
 		      do
 			{
 			  prev_scn = elf_nextscn (elf, prev_scn);
 			  GElf_Shdr prev_shdr_mem;
 			  GElf_Shdr *prev_shdr = gelf_getshdr (prev_scn,
 							       &prev_shdr_mem);
 			  if (unlikely (prev_shdr == NULL))
 			    goto elf_error;
 			  if (prev_shdr->sh_flags & SHF_ALLOC)
 			    {
 			      const GElf_Xword prev_align
 				= prev_shdr->sh_addralign ?: 1;

 			      prev_shdr->sh_addr
 				= (end + prev_align - 1) & -prev_align;
 			      end = prev_shdr->sh_addr + prev_shdr->sh_size;

 			      if (unlikely (! gelf_update_shdr (prev_scn,
 								prev_shdr)))
 				goto elf_error;
 			    }
 			}
 		      while (prev_scn != scn);
 		      continue;
 		    }

 		  end = shdr->sh_addr + shdr->sh_size;
 		  if (likely (shdr->sh_addr != 0)
 		      && unlikely (! gelf_update_shdr (scn, shdr)))
 		    goto elf_error;
 		}
 	      else
 		{
 		  /* The address is already assigned.  Just track it.  */
 		  if (first || end < shdr->sh_addr + shdr->sh_size)
 		    end = shdr->sh_addr + shdr->sh_size;
 		  if (first || bias > shdr->sh_addr)
 		    /* This is the lowest address in the module.  */
 		    bias = shdr->sh_addr;

 		  if ((shdr->sh_addr - bias + base) & (align - 1))
 		    /* This section winds up misaligned using BASE.
 		       Adjust BASE upwards to make it congruent to
 		       the lowest section address in the file modulo ALIGN.  */
 		    base = (((base + align - 1) & -align)
 			    + (bias & (align - 1)));
 		}

 	      first = false;
 	    }
 	}

       if (bias != 0)
 	{
 	  /* The section headers had nonzero sh_addr values.  The layout
 	     was already done.  We've just collected the total span.
 	     Now just compute the bias from the requested base.  */
 	  start = base;
 	  end = end - bias + start;
 	  bias = start - bias;
 	}
       break;

       /* Everything else has to have program headers.  */

     case ET_EXEC:
     case ET_CORE:
       /* An assigned base address is meaningless for these.  */
       base = 0;

     case ET_DYN:
     default:
       for (uint_fast16_t i = 0; i < ehdr->e_phnum; ++i)
 	{
 	  GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem);
 	  if (unlikely (ph == NULL))
 	    goto elf_error;
 	  if (ph->p_type == PT_LOAD)
 	    {
 	      if ((base & (ph->p_align - 1)) != 0)
 		base = (base + ph->p_align - 1) & -ph->p_align;
 	      start = base + (ph->p_vaddr & -ph->p_align);
 	      break;
 	    }
 	}
       bias = base;

       for (uint_fast16_t i = ehdr->e_phnum; i-- > 0;)
 	{
 	  GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem);
 	  if (unlikely (ph == NULL))
 	    goto elf_error;
 	  if (ph->p_type == PT_LOAD)
 	    {
 	      end = base + (ph->p_vaddr + ph->p_memsz);
 	      break;
 	    }
 	}

       if (end == 0)
 	{
 	  __libdwfl_seterrno (DWFL_E_NO_PHDR);
 	  return NULL;
 	}
       break;
     }

   Dwfl_Module *m = INTUSE(dwfl_report_module) (dwfl, name, start, end);
   if (m != NULL)
     {
       if (m->main.name == NULL)
 	{
 	  m->main.name = strdup (file_name);
 	  m->main.fd = fd;
 	}
       else if ((fd >= 0 && m->main.fd != fd)
 	       || strcmp (m->main.name, file_name))
 	{
 	  elf_end (elf);
 	overlap:
 	  m->gc = true;
 	  __libdwfl_seterrno (DWFL_E_OVERLAP);
 	  m = NULL;
 	}

       /* Preinstall the open ELF handle for the module.  */
       if (m->main.elf == NULL)
 	{
 	  m->main.elf = elf;
 	  m->main.bias = bias;
 	  m->e_type = ehdr->e_type;
 	}
       else
 	{
 	  elf_end (elf);
 	  if (m->main.bias != base)
 	    goto overlap;
 	}
     }
   return m;
 }

 Dwfl_Module *
 dwfl_report_elf (Dwfl *dwfl, const char *name,
 		 const char *file_name, int fd, GElf_Addr base)
 {
   bool closefd = false;
   if (fd < 0)
     {
       closefd = true;
       fd = open64 (file_name, O_RDONLY);
       if (fd < 0)
 	{
 	  __libdwfl_seterrno (DWFL_E_ERRNO);
 	  return NULL;
 	}
     }

   Elf *elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL);
   Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name,
 					   fd, elf, base);
   if (mod == NULL)
     {
       elf_end (elf);
       if (closefd)
 	close (fd);
     }

   return mod;
 }
 INTDEF (dwfl_report_elf)
	/* Report a module to libdwfl based on ELF program headers.
	Copyright (C) 2005, 2007 Red Hat, Inc.
	This file is part of Red Hat elfutils.

	Red Hat elfutils 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; version 2 of the License.

	Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
	Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

	In addition, as a special exception, Red Hat, Inc. gives You the
	additional right to link the code of Red Hat elfutils with code licensed
	under any Open Source Initiative certified open source license
	(http://www.opensource.org/licenses/index.php) which requires the
	distribution of source code with any binary distribution and to
	distribute linked combinations of the two. Non-GPL Code permitted under
	this exception must only link to the code of Red Hat elfutils through
	those well defined interfaces identified in the file named EXCEPTION
	found in the source code files (the "Approved Interfaces"). The files
	of Non-GPL Code may instantiate templates or use macros or inline
	functions from the Approved Interfaces without causing the resulting
	work to be covered by the GNU General Public License. Only Red Hat,
	Inc. may make changes or additions to the list of Approved Interfaces.
	Red Hat's grant of this exception is conditioned upon your not adding
	any new exceptions. If you wish to add a new Approved Interface or
	exception, please contact Red Hat. You must obey the GNU General Public
	License in all respects for all of the Red Hat elfutils code and other
	code used in conjunction with Red Hat elfutils except the Non-GPL Code
	covered by this exception. If you modify this file, you may extend this
	exception to your version of the file, but you are not obligated to do
	so. If you do not wish to provide this exception without modification,
	you must delete this exception statement from your version and license
	this file solely under the GPL without exception.

	Red Hat elfutils is an included package of the Open Invention Network.
	An included package of the Open Invention Network is a package for which
	Open Invention Network licensees cross-license their patents. No patent
	license is granted, either expressly or impliedly, by designation as an
	included package. Should you wish to participate in the Open Invention
	Network licensing program, please visit www.openinventionnetwork.com
	<http://www.openinventionnetwork.com>. */

	#include "libdwflP.h"
	#include <fcntl.h>
	#include <unistd.h>


	/* We start every ET_REL module at a moderately aligned boundary.
	This keeps the low addresses easy to read compared to a layout
	starting at 0 (as when using -e). It also makes it unlikely
	that a middle section will have a larger alignment and require
	rejiggering (see below). */
	#define REL_MIN_ALIGN ((GElf_Xword) 0x100)

	Dwfl_Module *
	internal_function
	__libdwfl_report_elf (Dwfl dwfl, const char name, const char *file_name,
	int fd, Elf *elf, GElf_Addr base)
	{
	GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);
	if (ehdr == NULL)
	{
	elf_error:
	__libdwfl_seterrno (DWFL_E_LIBELF);
	return NULL;
	}

	GElf_Addr start = 0, end = 0, bias = 0;
	switch (ehdr->e_type)
	{
	case ET_REL:
	/* For a relocatable object, we do an arbitrary section layout.
	By updating the section header in place, we leave the layout
	information to be found by relocation. */

	start = end = base = (base + REL_MIN_ALIGN - 1) & -REL_MIN_ALIGN;

	bool first = true;
	Elf_Scn *scn = NULL;
	while ((scn = elf_nextscn (elf, scn)) != NULL)
	{
	GElf_Shdr shdr_mem;
	GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
	if (unlikely (shdr == NULL))
	goto elf_error;

	if (shdr->sh_flags & SHF_ALLOC)
	{
	const GElf_Xword align = shdr->sh_addralign ?: 1;
	const GElf_Addr next = (end + align - 1) & -align;
	if (shdr->sh_addr == 0
	/* Once we've started doing layout we have to do it all,
	unless we just layed out the first section at 0 when
	it already was at 0. */
	\|\| (bias == 0 && end > start && end != next))
	{
	shdr->sh_addr = next;
	if (end == base)
	/* This is the first section assigned a location.
	Use its aligned address as the module's base. */
	start = base = shdr->sh_addr;
	else if (unlikely (base & (align - 1)))
	{
	/* If BASE has less than the maximum alignment of
	any section, we eat more than the optimal amount
	of padding and so make the module's apparent
	size come out larger than it would when placed
	at zero. So reset the layout with a better base. */

	start = end = base = (base + align - 1) & -align;
	Elf_Scn *prev_scn = NULL;
	do
	{
	prev_scn = elf_nextscn (elf, prev_scn);
	GElf_Shdr prev_shdr_mem;
	GElf_Shdr *prev_shdr = gelf_getshdr (prev_scn,
	&prev_shdr_mem);
	if (unlikely (prev_shdr == NULL))
	goto elf_error;
	if (prev_shdr->sh_flags & SHF_ALLOC)
	{
	const GElf_Xword prev_align
	= prev_shdr->sh_addralign ?: 1;

	prev_shdr->sh_addr
	= (end + prev_align - 1) & -prev_align;
	end = prev_shdr->sh_addr + prev_shdr->sh_size;

	if (unlikely (! gelf_update_shdr (prev_scn,
	prev_shdr)))
	goto elf_error;
	}
	}
	while (prev_scn != scn);
	continue;
	}

	end = shdr->sh_addr + shdr->sh_size;
	if (likely (shdr->sh_addr != 0)
	&& unlikely (! gelf_update_shdr (scn, shdr)))
	goto elf_error;
	}
	else
	{
	/* The address is already assigned. Just track it. */
	if (first \|\| end < shdr->sh_addr + shdr->sh_size)
	end = shdr->sh_addr + shdr->sh_size;
	if (first \|\| bias > shdr->sh_addr)
	/* This is the lowest address in the module. */
	bias = shdr->sh_addr;

	if ((shdr->sh_addr - bias + base) & (align - 1))
	/* This section winds up misaligned using BASE.
	Adjust BASE upwards to make it congruent to
	the lowest section address in the file modulo ALIGN. */
	base = (((base + align - 1) & -align)
	+ (bias & (align - 1)));
	}

	first = false;
	}
	}

	if (bias != 0)
	{
	/* The section headers had nonzero sh_addr values. The layout
	was already done. We've just collected the total span.
	Now just compute the bias from the requested base. */
	start = base;
	end = end - bias + start;
	bias = start - bias;
	}
	break;

	/* Everything else has to have program headers. */

	case ET_EXEC:
	case ET_CORE:
	/* An assigned base address is meaningless for these. */
	base = 0;

	case ET_DYN:
	default:
	for (uint_fast16_t i = 0; i < ehdr->e_phnum; ++i)
	{
	GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem);
	if (unlikely (ph == NULL))
	goto elf_error;
	if (ph->p_type == PT_LOAD)
	{
	if ((base & (ph->p_align - 1)) != 0)
	base = (base + ph->p_align - 1) & -ph->p_align;
	start = base + (ph->p_vaddr & -ph->p_align);
	break;
	}
	}
	bias = base;

	for (uint_fast16_t i = ehdr->e_phnum; i-- > 0;)
	{
	GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem);
	if (unlikely (ph == NULL))
	goto elf_error;
	if (ph->p_type == PT_LOAD)
	{
	end = base + (ph->p_vaddr + ph->p_memsz);
	break;
	}
	}

	if (end == 0)
	{
	__libdwfl_seterrno (DWFL_E_NO_PHDR);
	return NULL;
	}
	break;
	}

	Dwfl_Module *m = INTUSE(dwfl_report_module) (dwfl, name, start, end);
	if (m != NULL)
	{
	if (m->main.name == NULL)
	{
	m->main.name = strdup (file_name);
	m->main.fd = fd;
	}
	else if ((fd >= 0 && m->main.fd != fd)
	\|\| strcmp (m->main.name, file_name))
	{
	elf_end (elf);
	overlap:
	m->gc = true;
	__libdwfl_seterrno (DWFL_E_OVERLAP);
	m = NULL;
	}

	/* Preinstall the open ELF handle for the module. */
	if (m->main.elf == NULL)
	{
	m->main.elf = elf;
	m->main.bias = bias;
	m->e_type = ehdr->e_type;
	}
	else
	{
	elf_end (elf);
	if (m->main.bias != base)
	goto overlap;
	}
	}
	return m;
	}

	Dwfl_Module *
	dwfl_report_elf (Dwfl dwfl, const char name,
	const char *file_name, int fd, GElf_Addr base)
	{
	bool closefd = false;
	if (fd < 0)
	{
	closefd = true;
	fd = open64 (file_name, O_RDONLY);
	if (fd < 0)
	{
	__libdwfl_seterrno (DWFL_E_ERRNO);
	return NULL;
	}
	}

	Elf *elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL);
	Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name,
	fd, elf, base);
	if (mod == NULL)
	{
	elf_end (elf);
	if (closefd)
	close (fd);
	}

	return mod;
	}
	INTDEF (dwfl_report_elf)