libdwfl/linux-kernel-modules.c - platform/external/elfutils - Gitiles

 /* Standard libdwfl callbacks for debugging the running Linux kernel.
    Copyright (C) 2005 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 <config.h>
 #undef	_FILE_OFFSET_BITS	/* Doesn't jibe with fts.  */

 #include "libdwflP.h"
 #include <inttypes.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdio_ext.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sys/utsname.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <fts.h>


 #define MODULEDIRFMT	"/lib/modules/%s"

 #define MODULELIST	"/proc/modules"
 #define	SECADDRFMT	"/sys/module/%s/sections/%s"


 /* Try to open the given file as it is or under the debuginfo directory.  */
 static int
 try_kernel_name (Dwfl *dwfl, char **fname)
 {
   if (*fname == NULL)
     return -1;

   int fd = TEMP_FAILURE_RETRY (open64 (*fname, O_RDONLY));
   if (fd < 0)
     {
       char *debugfname = NULL;
       Dwfl_Module fakemod = { .dwfl = dwfl };
       fd = INTUSE(dwfl_standard_find_debuginfo) (&fakemod, NULL, NULL, 0,
 						 *fname, basename (*fname), 0,
 						 &debugfname);
       free (*fname);
       *fname = debugfname;
     }

   return fd;
 }

 static inline const char *
 kernel_release (void)
 {
   /* Cache the `uname -r` string we'll use.  */
   static struct utsname utsname;
   if (utsname.release[0] == '\0' && uname (&utsname) != 0)
     return NULL;
   return utsname.release;
 }

 static int
 report_kernel (Dwfl *dwfl, const char *release,
 	       int (*predicate) (const char *module, const char *file))
 {
   if (dwfl == NULL)
     return -1;

   char *fname = NULL;
   if (release[0] == '/')
     asprintf (&fname, "%s/vmlinux", release);
   else
     asprintf (&fname, "/boot/vmlinux-%s", release);
   int fd = try_kernel_name (dwfl, &fname);
   if (fd < 0 && release[0] != '/')
     {
       free (fname);
       fname = NULL;
       asprintf (&fname, MODULEDIRFMT "/vmlinux", release);
       fd = try_kernel_name (dwfl, &fname);
     }

   int result = 0;
   if (fd < 0)
     result = ((predicate != NULL && !(*predicate) ("kernel", NULL))
 	      ? 0 : errno ?: ENOENT);
   else
     {
       bool report = true;

       if (predicate != NULL)
 	{
 	  /* Let the predicate decide whether to use this one.  */
 	  int want = (*predicate) ("kernel", fname);
 	  if (want < 0)
 	    result = errno;
 	  report = want > 0;
 	}

       if (report
 	  && INTUSE(dwfl_report_elf) (dwfl, "kernel", fname, fd, 0) == NULL)
 	{
 	  close (fd);
 	  result = -1;
 	}
     }

   free (fname);

   return result;
 }

 /* Report a kernel and all its modules found on disk, for offline use.
    If RELEASE starts with '/', it names a directory to look in;
    if not, it names a directory to find under /lib/modules/;
    if null, /lib/modules/`uname -r` is used.
    Returns zero on success, -1 if dwfl_report_module failed,
    or an errno code if finding the files on disk failed.  */
 int
 dwfl_linux_kernel_report_offline (Dwfl *dwfl, const char *release,
 				  int (*predicate) (const char *module,
 						    const char *file))
 {
   if (release == NULL)
     {
       release = kernel_release ();
       if (release == NULL)
 	return errno;
     }

   /* First report the kernel.  */
   int result = report_kernel (dwfl, release, predicate);
   if (result == 0)
     {
       /* Do "find /lib/modules/RELEASE/kernel -name *.ko".  */

       char *modulesdir[] = { NULL, NULL };
       if (release[0] == '/')
 	modulesdir[0] = (char *) release;
       else
 	{
 	  asprintf (&modulesdir[0], MODULEDIRFMT "/kernel", release);
 	  if (modulesdir[0] == NULL)
 	    return errno;
 	}

       FTS *fts = fts_open (modulesdir, FTS_LOGICAL | FTS_NOSTAT, NULL);
       if (modulesdir[0] == (char *) release)
 	modulesdir[0] = NULL;
       if (fts == NULL)
 	{
 	  free (modulesdir[0]);
 	  return errno;
 	}

       FTSENT *f;
       while ((f = fts_read (fts)) != NULL)
 	{
 	  switch (f->fts_info)
 	    {
 	    case FTS_F:
 	    case FTS_NSOK:
 	      /* See if this file name matches "*.ko".  */
 	      if (f->fts_namelen > 3
 		  && !memcmp (f->fts_name + f->fts_namelen - 3, ".ko", 4))
 		{
 		  /* We have a .ko file to report.  Following the algorithm
 		     by which the kernel makefiles set KBUILD_MODNAME, we
 		     replace all ',' or '-' with '_' in the file name and
 		     call that the module name.  Modules could well be
 		     built using different embedded names than their file
 		     names.  To handle that, we would have to look at the
 		     __this_module.name contents in the module's text.  */

 		  char name[f->fts_namelen - 3 + 1];
 		  for (size_t i = 0; i < f->fts_namelen - 3U; ++i)
 		    if (f->fts_name[i] == '-' || f->fts_name[i] == ',')
 		      name[i] = '_';
 		    else
 		      name[i] = f->fts_name[i];
 		  name[f->fts_namelen - 3] = '\0';

 		  if (predicate != NULL)
 		    {
 		      /* Let the predicate decide whether to use this one.  */
 		      int want = (*predicate) (name, f->fts_path);
 		      if (want < 0)
 			{
 			  result = -1;
 			  break;
 			}
 		      if (!want)
 			continue;
 		    }

 		  if (dwfl_report_offline (dwfl, name,
 					   f->fts_path, -1) == NULL)
 		    {
 		      result = -1;
 		      break;
 		    }
 		}
 	      continue;

 	    case FTS_ERR:
 	    case FTS_DNR:
 	    case FTS_NS:
 	      result = f->fts_errno;
 	      break;

 	    default:
 	      continue;
 	    }

 	  /* We only get here in error cases.  */
 	  break;
 	}
       fts_close (fts);
       free (modulesdir[0]);
     }

   return result;
 }
 INTDEF (dwfl_linux_kernel_report_offline)


 /* Find the ELF file for the running kernel and dwfl_report_elf it.  */
 int
 dwfl_linux_kernel_report_kernel (Dwfl *dwfl)
 {
   const char *release = kernel_release ();
   if (release == NULL)
     return errno;

   return report_kernel (dwfl, release, NULL);
 }
 INTDEF (dwfl_linux_kernel_report_kernel)


 /* Dwfl_Callbacks.find_elf for the running Linux kernel and its modules.  */

 int
 dwfl_linux_kernel_find_elf (Dwfl_Module *mod __attribute__ ((unused)),
 			    void **userdata __attribute__ ((unused)),
 			    const char *module_name,
 			    Dwarf_Addr base __attribute__ ((unused)),
 			    char **file_name,
 			    Elf **elfp __attribute__ ((unused)))
 {
   const char *release = kernel_release ();
   if (release == NULL)
     return errno;

   /* Do "find /lib/modules/`uname -r`/kernel -name MODULE_NAME.ko".  */

   char *modulesdir[] = { NULL, NULL };
   asprintf (&modulesdir[0], MODULEDIRFMT "/kernel", release);
   if (modulesdir[0] == NULL)
     return -1;

   FTS *fts = fts_open (modulesdir, FTS_LOGICAL | FTS_NOSTAT, NULL);
   if (fts == NULL)
     {
       free (modulesdir[0]);
       return -1;
     }

   size_t namelen = strlen (module_name);

   /* This is a kludge.  There is no actual necessary relationship between
      the name of the .ko file installed and the module name the kernel
      knows it by when it's loaded.  The kernel's only idea of the module
      name comes from the name embedded in the object's magic
      .gnu.linkonce.this_module section.

      In practice, these module names match the .ko file names except for
      some using '_' and some using '-'.  So our cheap kludge is to look for
      two files when either a '_' or '-' appears in a module name, one using
      only '_' and one only using '-'.  */

   char alternate_name[namelen + 1];
   inline bool subst_name (char from, char to)
     {
       const char *n = memchr (module_name, from, namelen);
       if (n == NULL)
 	return false;
       char *a = mempcpy (alternate_name, module_name, n - module_name);
       *a++ = to;
       ++n;
       const char *p;
       while ((p = memchr (n, from, namelen - (n - module_name))) != NULL)
 	{
 	  a = mempcpy (a, n, p - n);
 	  *a++ = to;
 	  n = p + 1;
 	}
       memcpy (a, n, namelen - (n - module_name) + 1);
       return true;
     }
   if (!subst_name ('-', '_') && !subst_name ('_', '-'))
     alternate_name[0] = '\0';

   FTSENT *f;
   int error = ENOENT;
   while ((f = fts_read (fts)) != NULL)
     {
       error = ENOENT;
       switch (f->fts_info)
 	{
 	case FTS_F:
 	case FTS_NSOK:
 	  /* See if this file name is "MODULE_NAME.ko".  */
 	  if (f->fts_namelen == namelen + 3
 	      && !memcmp (f->fts_name + namelen, ".ko", 4)
 	      && (!memcmp (f->fts_name, module_name, namelen)
 		  || !memcmp (f->fts_name, alternate_name, namelen)))
 	    {
 	      int fd = open64 (f->fts_accpath, O_RDONLY);
 	      *file_name = strdup (f->fts_path);
 	      fts_close (fts);
 	      free (modulesdir[0]);
 	      if (fd < 0)
 		free (*file_name);
 	      else if (*file_name == NULL)
 		{
 		  close (fd);
 		  fd = -1;
 		}
 	      return fd;
 	    }
 	  break;

 	case FTS_ERR:
 	case FTS_DNR:
 	case FTS_NS:
 	  error = f->fts_errno;
 	  break;

 	default:
 	  break;
 	}
     }

   fts_close (fts);
   free (modulesdir[0]);
   errno = error;
   return -1;
 }
 INTDEF (dwfl_linux_kernel_find_elf)


 /* Dwfl_Callbacks.section_address for kernel modules in the running Linux.
    We read the information from /sys/module directly.  */

 int
 dwfl_linux_kernel_module_section_address
 (Dwfl_Module *mod __attribute__ ((unused)),
  void **userdata __attribute__ ((unused)),
  const char *modname, Dwarf_Addr base __attribute__ ((unused)),
  const char *secname, Elf32_Word shndx __attribute__ ((unused)),
  const GElf_Shdr *shdr __attribute__ ((unused)),
  Dwarf_Addr *addr)
 {
   char *sysfile = NULL;
   asprintf (&sysfile, SECADDRFMT, modname, secname);
   if (sysfile == NULL)
     return ENOMEM;

   FILE *f = fopen (sysfile, "r");
   free (sysfile);

   if (f == NULL)
     {
       if (errno == ENOENT)
 	{
 	  /* The .modinfo and .data.percpu sections are never kept
 	     loaded in the kernel.  If the kernel was compiled without
 	     CONFIG_MODULE_UNLOAD, the .exit.* sections are not
 	     actually loaded at all.

 	     Just relocate these bogusly to zero.  This part of the
 	     debug information will not be of any use.  */

 	  if (!strcmp (secname, ".modinfo")
 	      || !strcmp (secname, ".data.percpu")
 	      || !strncmp (secname, ".exit", 5))
 	    {
 	      *addr = 0;
 	      return DWARF_CB_OK;
 	    }

 	  /* The goofy PPC64 module_frob_arch_sections function tweaks
 	     the section names as a way to control other kernel code's
 	     behavior, and this cruft leaks out into the /sys information.
 	     The file name for ".init*" may actually look like "_init*".  */

 	  if (!strncmp (secname, ".init", 5))
 	    {
 	      sysfile = NULL;
 	      asprintf (&sysfile, SECADDRFMT "%s", modname, "_", &secname[1]);
 	      if (sysfile == NULL)
 		return ENOMEM;
 	      f = fopen (sysfile, "r");
 	      free (sysfile);
 	      if (f != NULL)
 		goto ok;
 	    }
 	}

       return DWARF_CB_ABORT;
     }

  ok:
   (void) __fsetlocking (f, FSETLOCKING_BYCALLER);

   int result = (fscanf (f, "%" PRIx64 "\n", addr) == 1 ? 0
 		: ferror_unlocked (f) ? errno : ENOEXEC);
   fclose (f);

   if (result == 0)
     return DWARF_CB_OK;

   errno = result;
   return DWARF_CB_ABORT;
 }
 INTDEF (dwfl_linux_kernel_module_section_address)

 int
 dwfl_linux_kernel_report_modules (Dwfl *dwfl)
 {
   FILE *f = fopen (MODULELIST, "r");
   if (f == NULL)
     return errno;

   (void) __fsetlocking (f, FSETLOCKING_BYCALLER);

   int result = 0;
   Dwarf_Addr modaddr;
   unsigned long int modsz;
   char modname[128];
   while (fscanf (f, "%128s %lu %*s %*s %*s %" PRIx64 "\n",
 		 modname, &modsz, &modaddr) == 3)
     if (INTUSE(dwfl_report_module) (dwfl, modname,
 				    modaddr, modaddr + modsz) == NULL)
       {
 	result = -1;
 	break;
       }

   if (result == 0)
     result = ferror_unlocked (f) ? errno : feof_unlocked (f) ? 0 : ENOEXEC;

   fclose (f);

   return result;
 }
 INTDEF (dwfl_linux_kernel_report_modules)
	/* Standard libdwfl callbacks for debugging the running Linux kernel.
	Copyright (C) 2005 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 <config.h>
	#undef _FILE_OFFSET_BITS /* Doesn't jibe with fts. */

	#include "libdwflP.h"
	#include <inttypes.h>
	#include <errno.h>
	#include <stdio.h>
	#include <stdio_ext.h>
	#include <string.h>
	#include <stdlib.h>
	#include <sys/utsname.h>
	#include <fcntl.h>
	#include <unistd.h>
	#include <fts.h>


	#define MODULEDIRFMT "/lib/modules/%s"

	#define MODULELIST "/proc/modules"
	#define SECADDRFMT "/sys/module/%s/sections/%s"


	/* Try to open the given file as it is or under the debuginfo directory. */
	static int
	try_kernel_name (Dwfl dwfl, char *fname)
	{
	if (*fname == NULL)
	return -1;

	int fd = TEMP_FAILURE_RETRY (open64 (*fname, O_RDONLY));
	if (fd < 0)
	{
	char *debugfname = NULL;
	Dwfl_Module fakemod = { .dwfl = dwfl };
	fd = INTUSE(dwfl_standard_find_debuginfo) (&fakemod, NULL, NULL, 0,
	fname, basename (fname), 0,
	&debugfname);
	free (*fname);
	*fname = debugfname;
	}

	return fd;
	}

	static inline const char *
	kernel_release (void)
	{
	/* Cache the `uname -r` string we'll use. */
	static struct utsname utsname;
	if (utsname.release[0] == '\0' && uname (&utsname) != 0)
	return NULL;
	return utsname.release;
	}

	static int
	report_kernel (Dwfl dwfl, const char release,
	int (predicate) (const char module, const char *file))
	{
	if (dwfl == NULL)
	return -1;

	char *fname = NULL;
	if (release[0] == '/')
	asprintf (&fname, "%s/vmlinux", release);
	else
	asprintf (&fname, "/boot/vmlinux-%s", release);
	int fd = try_kernel_name (dwfl, &fname);
	if (fd < 0 && release[0] != '/')
	{
	free (fname);
	fname = NULL;
	asprintf (&fname, MODULEDIRFMT "/vmlinux", release);
	fd = try_kernel_name (dwfl, &fname);
	}

	int result = 0;
	if (fd < 0)
	result = ((predicate != NULL && !(*predicate) ("kernel", NULL))
	? 0 : errno ?: ENOENT);
	else
	{
	bool report = true;

	if (predicate != NULL)
	{
	/* Let the predicate decide whether to use this one. */
	int want = (*predicate) ("kernel", fname);
	if (want < 0)
	result = errno;
	report = want > 0;
	}

	if (report
	&& INTUSE(dwfl_report_elf) (dwfl, "kernel", fname, fd, 0) == NULL)
	{
	close (fd);
	result = -1;
	}
	}

	free (fname);

	return result;
	}

	/* Report a kernel and all its modules found on disk, for offline use.
	If RELEASE starts with '/', it names a directory to look in;
	if not, it names a directory to find under /lib/modules/;
	if null, /lib/modules/`uname -r` is used.
	Returns zero on success, -1 if dwfl_report_module failed,
	or an errno code if finding the files on disk failed. */
	int
	dwfl_linux_kernel_report_offline (Dwfl dwfl, const char release,
	int (predicate) (const char module,
	const char *file))
	{
	if (release == NULL)
	{
	release = kernel_release ();
	if (release == NULL)
	return errno;
	}

	/* First report the kernel. */
	int result = report_kernel (dwfl, release, predicate);
	if (result == 0)
	{
	/* Do "find /lib/modules/RELEASE/kernel -name .ko". /

	char *modulesdir[] = { NULL, NULL };
	if (release[0] == '/')
	modulesdir[0] = (char *) release;
	else
	{
	asprintf (&modulesdir[0], MODULEDIRFMT "/kernel", release);
	if (modulesdir[0] == NULL)
	return errno;
	}

	FTS *fts = fts_open (modulesdir, FTS_LOGICAL \| FTS_NOSTAT, NULL);
	if (modulesdir[0] == (char *) release)
	modulesdir[0] = NULL;
	if (fts == NULL)
	{
	free (modulesdir[0]);
	return errno;
	}

	FTSENT *f;
	while ((f = fts_read (fts)) != NULL)
	{
	switch (f->fts_info)
	{
	case FTS_F:
	case FTS_NSOK:
	/* See if this file name matches ".ko". /
	if (f->fts_namelen > 3
	&& !memcmp (f->fts_name + f->fts_namelen - 3, ".ko", 4))
	{
	/* We have a .ko file to report. Following the algorithm
	by which the kernel makefiles set KBUILD_MODNAME, we
	replace all ',' or '-' with '_' in the file name and
	call that the module name. Modules could well be
	built using different embedded names than their file
	names. To handle that, we would have to look at the
	__this_module.name contents in the module's text. */

	char name[f->fts_namelen - 3 + 1];
	for (size_t i = 0; i < f->fts_namelen - 3U; ++i)
	if (f->fts_name[i] == '-' \|\| f->fts_name[i] == ',')
	name[i] = '_';
	else
	name[i] = f->fts_name[i];
	name[f->fts_namelen - 3] = '\0';

	if (predicate != NULL)
	{
	/* Let the predicate decide whether to use this one. */
	int want = (*predicate) (name, f->fts_path);
	if (want < 0)
	{
	result = -1;
	break;
	}
	if (!want)
	continue;
	}

	if (dwfl_report_offline (dwfl, name,
	f->fts_path, -1) == NULL)
	{
	result = -1;
	break;
	}
	}
	continue;

	case FTS_ERR:
	case FTS_DNR:
	case FTS_NS:
	result = f->fts_errno;
	break;

	default:
	continue;
	}

	/* We only get here in error cases. */
	break;
	}
	fts_close (fts);
	free (modulesdir[0]);
	}

	return result;
	}
	INTDEF (dwfl_linux_kernel_report_offline)


	/* Find the ELF file for the running kernel and dwfl_report_elf it. */
	int
	dwfl_linux_kernel_report_kernel (Dwfl *dwfl)
	{
	const char *release = kernel_release ();
	if (release == NULL)
	return errno;

	return report_kernel (dwfl, release, NULL);
	}
	INTDEF (dwfl_linux_kernel_report_kernel)


	/* Dwfl_Callbacks.find_elf for the running Linux kernel and its modules. */

	int
	dwfl_linux_kernel_find_elf (Dwfl_Module *mod __attribute__ ((unused)),
	void **userdata __attribute__ ((unused)),
	const char *module_name,
	Dwarf_Addr base __attribute__ ((unused)),
	char **file_name,
	Elf **elfp __attribute__ ((unused)))
	{
	const char *release = kernel_release ();
	if (release == NULL)
	return errno;

	/* Do "find /lib/modules/`uname -r`/kernel -name MODULE_NAME.ko". */

	char *modulesdir[] = { NULL, NULL };
	asprintf (&modulesdir[0], MODULEDIRFMT "/kernel", release);
	if (modulesdir[0] == NULL)
	return -1;

	FTS *fts = fts_open (modulesdir, FTS_LOGICAL \| FTS_NOSTAT, NULL);
	if (fts == NULL)
	{
	free (modulesdir[0]);
	return -1;
	}

	size_t namelen = strlen (module_name);

	/* This is a kludge. There is no actual necessary relationship between
	the name of the .ko file installed and the module name the kernel
	knows it by when it's loaded. The kernel's only idea of the module
	name comes from the name embedded in the object's magic
	.gnu.linkonce.this_module section.

	In practice, these module names match the .ko file names except for
	some using '_' and some using '-'. So our cheap kludge is to look for
	two files when either a '_' or '-' appears in a module name, one using
	only '_' and one only using '-'. */

	char alternate_name[namelen + 1];
	inline bool subst_name (char from, char to)
	{
	const char *n = memchr (module_name, from, namelen);
	if (n == NULL)
	return false;
	char *a = mempcpy (alternate_name, module_name, n - module_name);
	*a++ = to;
	++n;
	const char *p;
	while ((p = memchr (n, from, namelen - (n - module_name))) != NULL)
	{
	a = mempcpy (a, n, p - n);
	*a++ = to;
	n = p + 1;
	}
	memcpy (a, n, namelen - (n - module_name) + 1);
	return true;
	}
	if (!subst_name ('-', '_') && !subst_name ('_', '-'))
	alternate_name[0] = '\0';

	FTSENT *f;
	int error = ENOENT;
	while ((f = fts_read (fts)) != NULL)
	{
	error = ENOENT;
	switch (f->fts_info)
	{
	case FTS_F:
	case FTS_NSOK:
	/* See if this file name is "MODULE_NAME.ko". */
	if (f->fts_namelen == namelen + 3
	&& !memcmp (f->fts_name + namelen, ".ko", 4)
	&& (!memcmp (f->fts_name, module_name, namelen)
	\|\| !memcmp (f->fts_name, alternate_name, namelen)))
	{
	int fd = open64 (f->fts_accpath, O_RDONLY);
	*file_name = strdup (f->fts_path);
	fts_close (fts);
	free (modulesdir[0]);
	if (fd < 0)
	free (*file_name);
	else if (*file_name == NULL)
	{
	close (fd);
	fd = -1;
	}
	return fd;
	}
	break;

	case FTS_ERR:
	case FTS_DNR:
	case FTS_NS:
	error = f->fts_errno;
	break;

	default:
	break;
	}
	}

	fts_close (fts);
	free (modulesdir[0]);
	errno = error;
	return -1;
	}
	INTDEF (dwfl_linux_kernel_find_elf)


	/* Dwfl_Callbacks.section_address for kernel modules in the running Linux.
	We read the information from /sys/module directly. */

	int
	dwfl_linux_kernel_module_section_address
	(Dwfl_Module *mod __attribute__ ((unused)),
	void **userdata __attribute__ ((unused)),
	const char *modname, Dwarf_Addr base __attribute__ ((unused)),
	const char *secname, Elf32_Word shndx __attribute__ ((unused)),
	const GElf_Shdr *shdr __attribute__ ((unused)),
	Dwarf_Addr *addr)
	{
	char *sysfile = NULL;
	asprintf (&sysfile, SECADDRFMT, modname, secname);
	if (sysfile == NULL)
	return ENOMEM;

	FILE *f = fopen (sysfile, "r");
	free (sysfile);

	if (f == NULL)
	{
	if (errno == ENOENT)
	{
	/* The .modinfo and .data.percpu sections are never kept
	loaded in the kernel. If the kernel was compiled without
	CONFIG_MODULE_UNLOAD, the .exit.* sections are not
	actually loaded at all.

	Just relocate these bogusly to zero. This part of the
	debug information will not be of any use. */

	if (!strcmp (secname, ".modinfo")
	\|\| !strcmp (secname, ".data.percpu")
	\|\| !strncmp (secname, ".exit", 5))
	{
	*addr = 0;
	return DWARF_CB_OK;
	}

	/* The goofy PPC64 module_frob_arch_sections function tweaks
	the section names as a way to control other kernel code's
	behavior, and this cruft leaks out into the /sys information.
	The file name for ".init" may actually look like "_init". */

	if (!strncmp (secname, ".init", 5))
	{
	sysfile = NULL;
	asprintf (&sysfile, SECADDRFMT "%s", modname, "_", &secname[1]);
	if (sysfile == NULL)
	return ENOMEM;
	f = fopen (sysfile, "r");
	free (sysfile);
	if (f != NULL)
	goto ok;
	}
	}

	return DWARF_CB_ABORT;
	}

	ok:
	(void) __fsetlocking (f, FSETLOCKING_BYCALLER);

	int result = (fscanf (f, "%" PRIx64 "\n", addr) == 1 ? 0
	: ferror_unlocked (f) ? errno : ENOEXEC);
	fclose (f);

	if (result == 0)
	return DWARF_CB_OK;

	errno = result;
	return DWARF_CB_ABORT;
	}
	INTDEF (dwfl_linux_kernel_module_section_address)

	int
	dwfl_linux_kernel_report_modules (Dwfl *dwfl)
	{
	FILE *f = fopen (MODULELIST, "r");
	if (f == NULL)
	return errno;

	(void) __fsetlocking (f, FSETLOCKING_BYCALLER);

	int result = 0;
	Dwarf_Addr modaddr;
	unsigned long int modsz;
	char modname[128];
	while (fscanf (f, "%128s %lu %s %s %*s %" PRIx64 "\n",
	modname, &modsz, &modaddr) == 3)
	if (INTUSE(dwfl_report_module) (dwfl, modname,
	modaddr, modaddr + modsz) == NULL)
	{
	result = -1;
	break;
	}

	if (result == 0)
	result = ferror_unlocked (f) ? errno : feof_unlocked (f) ? 0 : ENOEXEC;

	fclose (f);

	return result;
	}
	INTDEF (dwfl_linux_kernel_report_modules)