ld.so: Introduce struct dl_exception

On 06/19/2017 05:29 PM, Florian Weimer wrote:
> This commit separates allocating and raising exceptions.  This
> simplifies catching and re-raising them because it is no longer
> necessary to make a temporary, on-stack copy of the exception message.

Ping?

I rebased the attached patch to current master.

I plan to remove the old handler functions in a subsequent patch.  This
patch only removes the alloca-based string manipulation, but leaves some
uses of the legacy interfaces in place.

Thanks,
Florian

On 08/10/2017 07:56 AM, Florian Weimer wrote:
> On 06/19/2017 05:29 PM, Florian Weimer wrote:
>> This commit separates allocating and raising exceptions.  This
>> simplifies catching and re-raising them because it is no longer
>> necessary to make a temporary, on-stack copy of the exception message.
> Ping?
> 
> I rebased the attached patch to current master.
> 
> I plan to remove the old handler functions in a subsequent patch.  This
> patch only removes the alloca-based string manipulation, but leaves some
> uses of the legacy interfaces in place.

Yeah, I noticed while reviewing that the old handler was almost unused after
you split up the sequence into create/throw/free.

Thanks for doing this kind of structured cleanup and for introducing more
structure to the internals of ld.so.

(1) High level.

The idea of grouping the exception data into a single structure is both
logical and modular and provides for a cleaner interface.

(2) Design.

The removal of the intermediate alloca's from strdupa'ing the strings is
big win. It clarifies the semantics of ownership of the string storage
and is a good step forward in improving the internal structure of the
loader.

(3) Implementation.

You added a minimal number of key functions to create, free, and use the
new dl_exception structure. You made good use of the API internally to
delete a lot of boilerplate code. The existing tests should cover the
exception code well so no new tests need to be added.

Overall it looks good to me.

> ld.so: Introduce struct dl_exception
> 
> This commit separates allocating and raising exceptions.  This
> simplifies catching and re-raising them because it is no longer
> necessary to make a temporary, on-stack copy of the exception message.
> 
> 2017-08-10  Florian Weimer  <fweimer@redhat.com>
> 
> 	Introduce ld.so exceptions.
> 	* sysdeps/generic/ldsodefs.h (struct dl_exception): Define.
> 	(_dl_exception_create, _dl_exception_create_format)
> 	(_dl_exception_free, _dl_signal_exception, _dl_signal_cexception)
> 	(_dl_catch_exception): Declare.
> 	(_dl_catch_error): Update comment.
> 	* elf/dl-error-skeleton.c (struct catch): Replace objname,
> 	errstring, malloced members with exception member.
> 	(_dl_out_of_memory): Remove.
> 	(fatal_error): New function, extracted from _dl_signal_error.
> 	(_dl_signal_exception, _dl_signal_cexception): New functions.
> 	(_dl_signal_error): Call _dl_exception_create to allocate an
> 	exception object.
> 	(_dl_catch_exception): New function, based on _dl_catch_error.
> 	(_dl_catch_error): Implement using _dl_catch_exception.
> 	* elf/dl-exception.c: New file.
> 	* elf/Makefile (dl-routines): Add dl-exception.
> 	(elide-routines.os): Likewise.
> 	* elf/Version (ld/GLIBC_PRIVATE): Add _dl_exception_create,
> 	_dl_exception_create_format, _dl_exception_free.
> 	* elf/dl-deps.c (_dl_map_object_deps): Use _dl_catch_exception and
> 	_dl_signal_exception.
> 	* elf/dl-lookup.c (make_string): Remove.
> 	(_dl_lookup_symbol_x): Use _dl_exception_create_format,
> 	_dl_signal_cexception, _dl_exception_free.
> 	* elf/dl-open.c (_dl_open): Use _dl_catch_exception and
> 	_dl_signal_exception.
> 	* elf/dl-sym.c (do_sym): Likewise.
> 	* elf/dl-version.c (make_string): Remove.
> 	(match_symbol): Use _dl_exception_create_format,
> 	_dl_signal_cexception, _dl_exception_free.
> 	(_dl_check_map_versions): Likewise.
> 	* sysdeps/generic/localplt.data (ld.so): Add _dl_signal_exception,
> 	_dl_catch_exception.
> 	* sysdeps/unix/sysv/linux/aarch64/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/alpha/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/arm/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/hppa/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/ia64/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/m68k/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/microblaze/localplt.data (ld.so):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/nios2/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/localplt.data
> 	(ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/localplt.data
> 	(ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc64/localplt.data (ld.so):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/s390/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/sh/localplt.data (ld.so): Likewise.
> 	* sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data (ld.so):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data (ld.so):
> 	Likewise.
> 	* sysdeps/x86_64/localplt.data (ld.so): Likewise.
> 
> diff --git a/elf/Makefile b/elf/Makefile
> index b54ebf8a98..d314a5fa7e 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -31,7 +31,8 @@ routines	= $(all-dl-routines) dl-support dl-iteratephdr \
>  dl-routines	= $(addprefix dl-,load lookup object reloc deps hwcaps \
>  				  runtime init fini debug misc \
>  				  version profile tls origin scope \
> -				  execstack caller open close trampoline)
> +				  execstack caller open close trampoline \
> +				  exception)

OK.

>  ifeq (yes,$(use-ldconfig))
>  dl-routines += dl-cache
>  endif
> @@ -51,7 +52,7 @@ endif
>  all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
>  # But they are absent from the shared libc, because that code is in ld.so.
>  elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \
> -		    dl-sysdep
> +		    dl-sysdep dl-exception

OK.

>  shared-only-routines += dl-caller
>  
>  # ld.so uses those routines, plus some special stuff for being the program
> diff --git a/elf/Versions b/elf/Versions
> index e65f2fac20..79ffaf73d2 100644
> --- a/elf/Versions
> +++ b/elf/Versions
> @@ -28,6 +28,7 @@ libc {
>      __libc_dlclose; __libc_dlopen_mode; __libc_dlsym;
>  
>      # Internal error handling support.  Interposes the functions in ld.so.
> +    _dl_signal_exception; _dl_catch_exception;

OK.

>      _dl_signal_error; _dl_catch_error;
>    }
>  }
> @@ -68,7 +69,11 @@ ld {
>      # Pointer protection.
>      __pointer_chk_guard;
>  
> +    # Internal error handling support.
> +    _dl_exception_create; _dl_exception_create_format; _dl_exception_free;

OK.

> +
>      # Internal error handling support.  Interposed by libc.so.
> +    _dl_signal_exception; _dl_catch_exception;

OK.

>      _dl_signal_error; _dl_catch_error;
>  
>      # Set value of a tunable.
> diff --git a/elf/dl-deps.c b/elf/dl-deps.c
> index 1b8bac6593..7c82d42be9 100644
> --- a/elf/dl-deps.c
> +++ b/elf/dl-deps.c
> @@ -165,8 +165,7 @@ _dl_map_object_deps (struct link_map *map,
>    const char *name;
>    int errno_saved;
>    int errno_reason;
> -  const char *errstring;
> -  const char *objname;
> +  struct dl_exception exception;
>  
>    /* No loaded object so far.  */
>    nlist = 0;
> @@ -200,7 +199,6 @@ _dl_map_object_deps (struct link_map *map,
>       alloca means we cannot use recursive function calls.  */
>    errno_saved = errno;
>    errno_reason = 0;
> -  errstring = NULL;
>    errno = 0;
>    name = NULL;
>    for (runp = known; runp; )
> @@ -250,17 +248,9 @@ _dl_map_object_deps (struct link_map *map,
>  		/* Store the tag in the argument structure.  */
>  		args.name = name;
>  
> -		bool malloced;
> -		int err = _dl_catch_error (&objname, &errstring, &malloced,
> -					   openaux, &args);
> -		if (__glibc_unlikely (errstring != NULL))
> +		int err = _dl_catch_exception (&exception, openaux, &args);
> +		if (__glibc_unlikely (exception.errstring != NULL))
>  		  {
> -		    char *new_errstring = strdupa (errstring);
> -		    objname = strdupa (objname);
> -		    if (malloced)
> -		      free ((char *) errstring);
> -		    errstring = new_errstring;
> -
>  		    if (err)
>  		      errno_reason = err;
>  		    else
> @@ -313,31 +303,18 @@ _dl_map_object_deps (struct link_map *map,
>  		/* We must be prepared that the addressed shared
>  		   object is not available.  For filter objects the dependency
>  		   must be available.  */
> -		bool malloced;
> -		int err = _dl_catch_error (&objname, &errstring, &malloced,
> -					openaux, &args);
> -
> -		if (__glibc_unlikely (errstring != NULL))
> +		int err = _dl_catch_exception (&exception, openaux, &args);
> +		if (__glibc_unlikely (exception.errstring != NULL))
>  		  {
>  		    if (d->d_tag == DT_AUXILIARY)
>  		      {
>  			/* We are not interested in the error message.  */
> -			assert (errstring != NULL);
> -			if (malloced)
> -			  free ((char *) errstring);
> -
> +			_dl_exception_free (&exception);
>  			/* Simply ignore this error and continue the work.  */
>  			continue;
>  		      }
>  		    else
>  		      {
> -
> -			char *new_errstring = strdupa (errstring);
> -			objname = strdupa (objname);
> -			if (malloced)
> -			  free ((char *) errstring);
> -			errstring = new_errstring;
> -
>  			if (err)
>  			  errno_reason = err;
>  			else
> @@ -683,6 +660,6 @@ Filters not supported with LD_TRACE_PRELINKING"));
>      _dl_scope_free (old_l_initfini);
>  
>    if (errno_reason)
> -    _dl_signal_error (errno_reason == -1 ? 0 : errno_reason, objname,
> -		      NULL, errstring);
> +    _dl_signal_exception (errno_reason == -1 ? 0 : errno_reason,
> +			  &exception, NULL);

OK.

>  }
> diff --git a/elf/dl-error-skeleton.c b/elf/dl-error-skeleton.c
> index 8e5888d4bd..8de6c87abf 100644
> --- a/elf/dl-error-skeleton.c
> +++ b/elf/dl-error-skeleton.c
> @@ -39,10 +39,7 @@
>     _dl_signal_error.  */
>  struct catch
>    {
> -    const char **objname;	/* Object/File name.  */
> -    const char **errstring;	/* Error detail filled in here.  */
> -    bool *malloced;		/* Nonzero if the string is malloced
> -				   by the libc malloc.  */
> +    struct dl_exception *exception; /* The exception data is stored there.  */

OK.

>      volatile int *errcode;	/* Return value of _dl_signal_error.  */
>      jmp_buf env;		/* longjmp here on error.  */
>    };
> @@ -60,11 +57,6 @@ static __thread struct catch *catch_hook attribute_tls_model_ie;
>  static struct catch *catch_hook;
>  #endif
>  
> -/* This message we return as a last resort.  We define the string in a
> -   variable since we have to avoid freeing it and so have to enable
> -   a pointer comparison.  See below and in dlfcn/dlerror.c.  */
> -static const char _dl_out_of_memory[] = "out of memory";
> -

OK.

>  #if DL_ERROR_BOOTSTRAP
>  /* This points to a function which is called when an continuable error is
>     received.  Unlike the handling of `catch' this function may return.
> @@ -76,6 +68,41 @@ static const char _dl_out_of_memory[] = "out of memory";
>  static receiver_fct receiver;
>  #endif /* DL_ERROR_BOOTSTRAP */
>  
> +/* Lossage while resolving the program's own symbols is always fatal.  */
> +static void
> +__attribute__ ((noreturn))
> +fatal_error (int errcode, const char *objname, const char *occasion,
> +	     const char *errstring)
> +{
> +  char buffer[1024];
> +  _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
> +		    RTLD_PROGNAME,
> +		    occasion ?: N_("error while loading shared libraries"),
> +		    objname, *objname ? ": " : "",
> +		    errstring, errcode ? ": " : "",
> +		    (errcode
> +		     ? __strerror_r (errcode, buffer, sizeof buffer)
> +		     : ""));
> +}

OK.

> +
> +void
> +_dl_signal_exception (int errcode, struct dl_exception *exception,
> +		      const char *occasion)
> +{
> +  struct catch *lcatch = catch_hook;
> +  if (lcatch != NULL)
> +    {
> +      *lcatch->exception = *exception;
> +      *lcatch->errcode = errcode;
> +
> +      /* We do not restore the signal mask because none was saved.  */
> +      __longjmp (lcatch->env[0].__jmpbuf, 1);
> +    }
> +  else
> +    fatal_error (errcode, exception->objname, occasion, exception->errstring);
> +}
> +libc_hidden_def (_dl_signal_exception)

OK.

> +
>  void
>  internal_function
>  _dl_signal_error (int errcode, const char *objname, const char *occation,
> @@ -86,66 +113,43 @@ _dl_signal_error (int errcode, const char *objname, const char *occation,
>    if (! errstring)
>      errstring = N_("DYNAMIC LINKER BUG!!!");
>  
> -  if (objname == NULL)
> -    objname = "";
>    if (lcatch != NULL)
>      {
> -      /* We are inside _dl_catch_error.  Return to it.  We have to
> -	 duplicate the error string since it might be allocated on the
> -	 stack.  The object name is always a string constant.  */
> -      size_t len_objname = strlen (objname) + 1;
> -      size_t len_errstring = strlen (errstring) + 1;
> -
> -      char *errstring_copy = malloc (len_objname + len_errstring);
> -      if (errstring_copy != NULL)
> -	{
> -	  /* Make a copy of the object file name and the error string.  */
> -	  *lcatch->objname = memcpy (__mempcpy (errstring_copy,
> -						errstring, len_errstring),
> -				     objname, len_objname);
> -	  *lcatch->errstring = errstring_copy;
> -
> -	  /* If the main executable is relocated it means the libc's malloc
> -	     is used.  */
> -          bool malloced = true;
> -#ifdef SHARED
> -	  malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL
> -                      && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0));
> -#endif
> -	  *lcatch->malloced = malloced;
> -	}
> -      else
> -	{
> -	  /* This is better than nothing.  */
> -	  *lcatch->objname = "";
> -	  *lcatch->errstring = _dl_out_of_memory;
> -	  *lcatch->malloced = false;
> -	}
> -
> +      _dl_exception_create (lcatch->exception, objname, errstring);

OK.

>        *lcatch->errcode = errcode;
>  
>        /* We do not restore the signal mask because none was saved.  */
>        __longjmp (lcatch->env[0].__jmpbuf, 1);
>      }
>    else
> -    {
> -      /* Lossage while resolving the program's own symbols is always fatal.  */
> -      char buffer[1024];
> -      _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
> -			RTLD_PROGNAME,
> -			occation ?: N_("error while loading shared libraries"),
> -			objname, *objname ? ": " : "",
> -			errstring, errcode ? ": " : "",
> -			(errcode
> -			 ? __strerror_r (errcode, buffer, sizeof buffer)
> -			 : ""));
> -    }
> +    fatal_error (errcode, objname, occation, errstring);

OK.

>  }
>  libc_hidden_def (_dl_signal_error)
>  
>  
>  #if DL_ERROR_BOOTSTRAP
>  void
> +_dl_signal_cexception (int errcode, struct dl_exception *exception,
> +		       const char *occasion)
> +{
> +  if (__builtin_expect (GLRO(dl_debug_mask)
> +			& ~(DL_DEBUG_STATISTICS|DL_DEBUG_PRELINK), 0))
> +    _dl_debug_printf ("%s: error: %s: %s (%s)\n",
> +		      exception->objname, occasion,
> +		      exception->errstring, receiver ? "continued" : "fatal");
> +
> +  if (receiver)
> +    {
> +      /* We are inside _dl_receive_error.  Call the user supplied
> +	 handler and resume the work.  The receiver will still be
> +	 installed.  */
> +      (*receiver) (errcode, exception->objname, exception->errstring);
> +    }
> +  else
> +    _dl_signal_exception (errcode, exception, occasion);
> +}

OK.

> +
> +void
>  internal_function
>  _dl_signal_cerror (int errcode, const char *objname, const char *occation,
>  		   const char *errstring)
> @@ -167,11 +171,9 @@ _dl_signal_cerror (int errcode, const char *objname, const char *occation,
>  }
>  #endif /* DL_ERROR_BOOTSTRAP */
>  
> -
>  int
> -internal_function
> -_dl_catch_error (const char **objname, const char **errstring,
> -		 bool *mallocedp, void (*operate) (void *), void *args)
> +_dl_catch_exception (struct dl_exception *exception,
> +		     void (*operate) (void *), void *args)

OK.

>  {
>    /* We need not handle `receiver' since setting a `catch' is handled
>       before it.  */
> @@ -184,9 +186,7 @@ _dl_catch_error (const char **objname, const char **errstring,
>  
>    struct catch c;
>    /* Don't use an initializer since we don't need to clear C.env.  */
> -  c.objname = objname;
> -  c.errstring = errstring;
> -  c.malloced = mallocedp;
> +  c.exception = exception;

OK.

>    c.errcode = &errcode;
>  
>    struct catch *const old = catch_hook;
> @@ -197,17 +197,30 @@ _dl_catch_error (const char **objname, const char **errstring,
>      {
>        (*operate) (args);
>        catch_hook = old;
> -      *objname = NULL;
> -      *errstring = NULL;
> -      *mallocedp = false;
> +      *exception = (struct dl_exception) { NULL };
>        return 0;
>      }
>  
> -  /* We get here only if we longjmp'd out of OPERATE.  _dl_signal_error has
> -     already stored values into *OBJNAME, *ERRSTRING, and *MALLOCEDP.  */
> +  /* We get here only if we longjmp'd out of OPERATE.
> +     _dl_signal_exception has already stored values into
> +     *EXCEPTION.  */
>    catch_hook = old;
>    return errcode;
>  }
> +libc_hidden_def (_dl_catch_exception)
> +
> +int
> +internal_function
> +_dl_catch_error (const char **objname, const char **errstring,
> +		 bool *mallocedp, void (*operate) (void *), void *args)
> +{
> +  struct dl_exception exception;
> +  int errorcode = _dl_catch_exception (&exception, operate, args);
> +  *objname = exception.objname;
> +  *errstring = exception.errstring;
> +  *mallocedp = exception.message_buffer == exception.errstring;
> +  return errorcode;
> +}

OK.

>  libc_hidden_def (_dl_catch_error)
>  
>  #if DL_ERROR_BOOTSTRAP
> diff --git a/elf/dl-exception.c b/elf/dl-exception.c
> new file mode 100644
> index 0000000000..b4d0ca7578
> --- /dev/null
> +++ b/elf/dl-exception.c
> @@ -0,0 +1,202 @@
> +/* ld.so error exception allocation and deallocation.
> +   Copyright (C) 1995-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library 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
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <ldsodefs.h>
> +#include <limits.h>
> +#include <stdarg.h>
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +/* This message we return as a last resort.  We define the string in a
> +   variable since we have to avoid freeing it and so have to enable
> +   a pointer comparison.  See below and in dlfcn/dlerror.c.  */
> +static const char _dl_out_of_memory[] = "out of memory";
> +
> +/* Dummy allocation object used if allocating the message buffer
> +   fails.  */
> +static void
> +oom_exception (struct dl_exception *exception)
> +{
> +  exception->objname = "";
> +  exception->errstring = _dl_out_of_memory;
> +  exception->message_buffer = NULL;
> +}
> +
> +static void
> +__attribute__ ((noreturn))
> +length_mismatch (void)
> +{
> +  _dl_fatal_printf ("Fatal error: "
> +                    "length accounting in _dl_exception_create_format\n");
> +}
> +
> +/* Adjust the message buffer to indicate whether it is possible to
> +   free it.  EXCEPTION->errstring must be a potentially deallocatable
> +   pointer.  */
> +static void
> +adjust_message_buffer (struct dl_exception *exception)
> +{
> +  /* If the main executable is relocated it means the libc's malloc
> +     is used.  */
> +  bool malloced = true;
> +#ifdef SHARED
> +  malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL
> +              && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0));
> +#endif
> +  if (malloced)
> +    exception->message_buffer = (char *) exception->errstring;
> +  else
> +    exception->message_buffer = NULL;
> +}
> +
> +void
> +_dl_exception_create (struct dl_exception *exception, const char *objname,
> +                      const char *errstring)
> +{
> +  if (objname == NULL)
> +    objname = "";
> +  size_t len_objname = strlen (objname) + 1;
> +  size_t len_errstring = strlen (errstring) + 1;
> +  char *errstring_copy = malloc (len_objname + len_errstring);
> +  if (errstring_copy != NULL)
> +    {
> +      /* Make a copy of the object file name and the error string.  */
> +      exception->objname = memcpy (__mempcpy (errstring_copy,
> +                                              errstring, len_errstring),
> +                                   objname, len_objname);
> +      exception->errstring = errstring_copy;
> +      adjust_message_buffer (exception);
> +    }
> +  else
> +    oom_exception (exception);
> +}
> +rtld_hidden_def (_dl_exception_create)
> +
> +void
> +_dl_exception_create_format (struct dl_exception *exception, const char *objname,
> +                             const char *fmt, ...)
> +{
> +  if (objname == NULL)
> +    objname = "";
> +  size_t len_objname = strlen (objname) + 1;
> +  /* Compute the length of the result.  Include room for two NUL
> +     bytes.  */
> +  size_t length = len_objname + 1;
> +  {
> +    va_list ap;
> +    va_start (ap, fmt);
> +    for (const char *p = fmt; *p != '\0'; ++p)
> +      if (*p == '%')
> +        {
> +          ++p;
> +          switch (*p)
> +            {
> +            case 's':
> +              length += strlen (va_arg (ap, const char *));
> +              break;
> +            default:
> +              /* Assumed to be '%'.  */
> +              ++length;
> +              break;
> +            }
> +        }
> +      else
> +        ++length;
> +    va_end (ap);
> +  }

OK.

> +
> +  if (length > PTRDIFF_MAX)
> +    {
> +      oom_exception (exception);
> +      return;
> +    }
> +  char *errstring = malloc (length);
> +  if (errstring == NULL)
> +    {
> +      oom_exception (exception);
> +      return;
> +    }
> +  exception->errstring = errstring;
> +  adjust_message_buffer (exception);
> +
> +  /* Copy the error message to errstring.  */
> +  {
> +    /* Next byte to be written in errstring.  */
> +    char *wptr = errstring;
> +    /* End of the allocated string.  */
> +    char *const end = errstring + length;
> +
> +    va_list ap;
> +    va_start (ap, fmt);
> +
> +    for (const char *p = fmt; *p != '\0'; ++p)
> +      if (*p == '%')
> +        {
> +          ++p;
> +          switch (*p)
> +            {
> +            case 's':
> +              {
> +                const char *ptr = va_arg (ap, const char *);
> +                size_t len_ptr = strlen (ptr);
> +                if (len_ptr > end - wptr)
> +                  length_mismatch ();
> +                wptr = __mempcpy (wptr, ptr, len_ptr);
> +              }
> +              break;
> +            case '%':
> +              if (wptr == end)
> +                length_mismatch ();
> +              *wptr = '%';
> +              ++wptr;
> +              break;
> +            default:
> +              _dl_fatal_printf ("Fatal error:"
> +                                " invalid format in exception string\n");
> +            }
> +        }
> +      else
> +        {
> +          if (wptr == end)
> +            length_mismatch ();
> +          *wptr = *p;
> +          ++wptr;
> +        }
> +
> +    if (wptr == end)
> +      length_mismatch ();
> +    *wptr = '\0';
> +    ++wptr;
> +    if (len_objname != end - wptr)
> +      length_mismatch ();
> +    exception->objname = memcpy (wptr, objname, len_objname);
> +  }
> +}

OK.

> +rtld_hidden_def (_dl_exception_create_format)
> +
> +void
> +_dl_exception_free (struct dl_exception *exception)
> +{
> +  free (exception->message_buffer);
> +  exception->objname = NULL;
> +  exception->errstring = NULL;
> +  exception->message_buffer = NULL;
> +}
> +rtld_hidden_def (_dl_exception_free)
> diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
> index 3d2369dbf2..645dc3ebb4 100644
> --- a/elf/dl-lookup.c
> +++ b/elf/dl-lookup.c
> @@ -47,23 +47,6 @@ struct sym_val
>    };
>  
>  
> -#define make_string(string, rest...) \
> -  ({									      \
> -    const char *all[] = { string, ## rest };				      \
> -    size_t len, cnt;							      \
> -    char *result, *cp;							      \
> -									      \
> -    len = 1;								      \
> -    for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)		      \
> -      len += strlen (all[cnt]);						      \
> -									      \
> -    cp = result = alloca (len);						      \
> -    for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)		      \
> -      cp = __stpcpy (cp, all[cnt]);					      \
> -									      \
> -    result;								      \
> -  })
> -

OK.

>  /* Statistics function.  */
>  #ifdef SHARED
>  # define bump_num_relocations() ++GL(dl_num_relocations)
> @@ -843,17 +826,16 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
>  	     for unversioned lookups.  */
>  	  assert (version != NULL);
>  	  const char *reference_name = undef_map ? undef_map->l_name : "";
> -
> +	  struct dl_exception exception;
>  	  /* XXX We cannot translate the message.  */
> -	  _dl_signal_cerror (0, DSO_FILENAME (reference_name),
> -			     N_("relocation error"),
> -			     make_string ("symbol ", undef_name, ", version ",
> -					  version->name,
> -					  " not defined in file ",
> -					  version->filename,
> -					  " with link time reference",
> -					  res == -2
> -					  ? " (no version symbols)" : ""));
> +	  _dl_exception_create_format
> +	    (&exception, DSO_FILENAME (reference_name),
> +	     "symbol %s version %s not defined in file %s"
> +	     " with link time reference%s",
> +	     undef_name, version->name, version->filename,
> +	     res == -2 ? " (no version symbols)" : "");
> +	  _dl_signal_cexception (0, &exception, N_("relocation error"));
> +	  _dl_exception_free (&exception);
>  	  *ref = NULL;
>  	  return 0;
>  	}
> @@ -869,12 +851,14 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
>  	  const char *versionstr = version ? ", version " : "";
>  	  const char *versionname = (version && version->name
>  				     ? version->name : "");
> -
> +	  struct dl_exception exception;
>  	  /* XXX We cannot translate the message.  */
> -	  _dl_signal_cerror (0, DSO_FILENAME (reference_name),
> -			     N_("symbol lookup error"),
> -			     make_string ("undefined symbol: ", undef_name,
> -					  versionstr, versionname));
> +	  _dl_exception_create_format
> +	    (&exception, DSO_FILENAME (reference_name),
> +	     "undefined symbol: %s%s%s",
> +	     undef_name, versionstr, versionname);
> +	  _dl_signal_cexception (0, &exception, N_("symbol lookup error"));
> +	  _dl_exception_free (&exception);

OK.

>  	}
>        *ref = NULL;
>        return 0;
> diff --git a/elf/dl-open.c b/elf/dl-open.c
> index cec54db413..91a1d1a4f8 100644
> --- a/elf/dl-open.c
> +++ b/elf/dl-open.c
> @@ -643,11 +643,8 @@ no more namespaces available for dlmopen()"));
>    args.argv = argv;
>    args.env = env;
>  
> -  const char *objname;
> -  const char *errstring;
> -  bool malloced;
> -  int errcode = _dl_catch_error (&objname, &errstring, &malloced,
> -				 dl_open_worker, &args);
> +  struct dl_exception exception;
> +  int errcode = _dl_catch_exception (&exception, dl_open_worker, &args);
>  
>  #if defined USE_LDCONFIG && !defined MAP_COPY
>    /* We must unmap the cache file.  */
> @@ -655,7 +652,7 @@ no more namespaces available for dlmopen()"));
>  #endif
>  
>    /* See if an error occurred during loading.  */
> -  if (__glibc_unlikely (errstring != NULL))
> +  if (__glibc_unlikely (exception.errstring != NULL))
>      {
>        /* Remove the object from memory.  It may be in an inconsistent
>  	 state if relocation failed, for example.  */
> @@ -679,28 +676,8 @@ no more namespaces available for dlmopen()"));
>        /* Release the lock.  */
>        __rtld_lock_unlock_recursive (GL(dl_load_lock));
>  
> -      /* Make a local copy of the error string so that we can release the
> -	 memory allocated for it.  */
> -      size_t len_errstring = strlen (errstring) + 1;
> -      char *local_errstring;
> -      if (objname == errstring + len_errstring)
> -	{
> -	  size_t total_len = len_errstring + strlen (objname) + 1;
> -	  local_errstring = alloca (total_len);
> -	  memcpy (local_errstring, errstring, total_len);
> -	  objname = local_errstring + len_errstring;
> -	}
> -      else
> -	{
> -	  local_errstring = alloca (len_errstring);
> -	  memcpy (local_errstring, errstring, len_errstring);
> -	}
> -
> -      if (malloced)
> -	free ((char *) errstring);
> -
>        /* Reraise the error.  */
> -      _dl_signal_error (errcode, objname, NULL, local_errstring);
> +      _dl_signal_exception (errcode, &exception, NULL);

OK.

>      }
>  
>    assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
> diff --git a/elf/dl-sym.c b/elf/dl-sym.c
> index 7cd6e97643..fb54a91858 100644
> --- a/elf/dl-sym.c
> +++ b/elf/dl-sym.c
> @@ -119,26 +119,11 @@ do_sym (void *handle, const char *name, void *who,
>  	  args.refp = &ref;
>  
>  	  THREAD_GSCOPE_SET_FLAG ();
> -
> -	  const char *objname;
> -	  const char *errstring = NULL;
> -	  bool malloced;
> -	  int err = _dl_catch_error (&objname, &errstring, &malloced,
> -				     call_dl_lookup, &args);
> -
> +	  struct dl_exception exception;
> +	  int err = _dl_catch_exception (&exception, call_dl_lookup, &args);
>  	  THREAD_GSCOPE_RESET_FLAG ();
> -
> -	  if (__glibc_unlikely (errstring != NULL))
> -	    {
> -	      /* The lookup was unsuccessful.  Rethrow the error.  */
> -	      char *errstring_dup = strdupa (errstring);
> -	      char *objname_dup = strdupa (objname);
> -	      if (malloced)
> -		free ((char *) errstring);
> -
> -	      _dl_signal_error (err, objname_dup, NULL, errstring_dup);
> -	      /* NOTREACHED */
> -	    }
> +	  if (__glibc_unlikely (exception.errstring != NULL))
> +	    _dl_signal_exception (err, &exception, NULL);
>  

OK.

>  	  result = args.map;
>  	}
> diff --git a/elf/dl-version.c b/elf/dl-version.c
> index c00078e5e4..c0d76ad42a 100644
> --- a/elf/dl-version.c
> +++ b/elf/dl-version.c
> @@ -27,25 +27,6 @@
>  
>  #include <assert.h>
>  
> -
> -#define make_string(string, rest...) \
> -  ({									      \
> -    const char *all[] = { string, ## rest };				      \
> -    size_t len, cnt;							      \
> -    char *result, *cp;							      \
> -									      \
> -    len = 1;								      \
> -    for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)		      \
> -      len += strlen (all[cnt]);						      \
> -									      \
> -    cp = result = alloca (len);						      \
> -    for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt)		      \
> -      cp = __stpcpy (cp, all[cnt]);					      \
> -									      \
> -    result;								      \
> -  })
> -
> -

OK.

>  static inline struct link_map *
>  __attribute ((always_inline))
>  find_needed (const char *name, struct link_map *map)
> @@ -78,8 +59,8 @@ match_symbol (const char *name, Lmid_t ns, ElfW(Word) hash, const char *string,
>    ElfW(Addr) def_offset;
>    ElfW(Verdef) *def;
>    /* Initialize to make the compiler happy.  */
> -  const char *errstring = NULL;
>    int result = 0;
> +  struct dl_exception exception;
>  
>    /* Display information about what we are doing while debugging.  */
>    if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_VERSIONS))
> @@ -96,8 +77,9 @@ checking for version `%s' in file %s [%lu] required by file %s [%lu]\n",
>        if (verbose)
>  	{
>  	  /* XXX We cannot translate the messages.  */
> -	  errstring = make_string ("\
> -no version information available (required by ", name, ")");
> +	  _dl_exception_create_format
> +	    (&exception, DSO_FILENAME (map->l_name),
> +	     "no version information available (required by %s)", name);
>  	  goto call_cerror;
>  	}
>        return 0;
> @@ -116,10 +98,10 @@ no version information available (required by ", name, ")");
>  	  char buf[20];
>  	  buf[sizeof (buf) - 1] = '\0';
>  	  /* XXX We cannot translate the message.  */
> -	  errstring = make_string ("unsupported version ",
> -				   _itoa (def->vd_version,
> -					  &buf[sizeof (buf) - 1], 10, 0),
> -				   " of Verdef record");
> +	  _dl_exception_create_format
> +	    (&exception, DSO_FILENAME (map->l_name),
> +	     "unsupported version %s of Verdef record",
> +	     _itoa (def->vd_version, &buf[sizeof (buf) - 1], 10, 0));
>  	  result = 1;
>  	  goto call_cerror;
>  	}
> @@ -150,20 +132,22 @@ no version information available (required by ", name, ")");
>        if (verbose)
>  	{
>  	  /* XXX We cannot translate the message.  */
> -	  errstring = make_string ("weak version `", string,
> -				   "' not found (required by ", name, ")");
> +	  _dl_exception_create_format
> +	    (&exception, DSO_FILENAME (map->l_name),
> +	     "weak version `%s' not found (required by %s)", string, name);
>  	  goto call_cerror;
>  	}
>        return 0;
>      }
>  
>    /* XXX We cannot translate the message.  */
> -  errstring = make_string ("version `", string, "' not found (required by ",
> -			   name, ")");
> +  _dl_exception_create_format
> +    (&exception, DSO_FILENAME (map->l_name),
> +     "version `%s' not found (required by %s)", string, name);
>    result = 1;
>   call_cerror:
> -  _dl_signal_cerror (0, DSO_FILENAME (map->l_name),
> -		     N_("version lookup error"), errstring);
> +  _dl_signal_cexception (0, &exception, N_("version lookup error"));
> +  _dl_exception_free (&exception);
>    return result;
>  }
>  
> @@ -181,8 +165,8 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
>    /* We need to find out which is the highest version index used
>      in a dependecy.  */
>    unsigned int ndx_high = 0;
> +  struct dl_exception exception;
>    /* Initialize to make the compiler happy.  */
> -  const char *errstring = NULL;
>    int errval = 0;
>  
>    /* If we don't have a string table, we must be ok.  */
> @@ -205,13 +189,12 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
>  	  char buf[20];
>  	  buf[sizeof (buf) - 1] = '\0';
>  	  /* XXX We cannot translate the message.  */
> -	  errstring = make_string ("unsupported version ",
> -				   _itoa (ent->vn_version,
> -					  &buf[sizeof (buf) - 1], 10, 0),
> -				   " of Verneed record\n");
> +	  _dl_exception_create_format
> +	    (&exception, DSO_FILENAME (map->l_name),
> +	     "unsupported version %s of Verneed record",
> +	     _itoa (ent->vn_version, &buf[sizeof (buf) - 1], 10, 0));
>  	call_error:
> -	  _dl_signal_error (errval, DSO_FILENAME (map->l_name),
> -			    NULL, errstring);
> +	  _dl_signal_exception (errval, &exception, NULL);
>  	}
>  
>        while (1)
> @@ -293,7 +276,9 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
>  	calloc (ndx_high + 1, sizeof (*map->l_versions));
>        if (__glibc_unlikely (map->l_versions == NULL))
>  	{
> -	  errstring = N_("cannot allocate version reference table");
> +	  _dl_exception_create
> +	    (&exception, DSO_FILENAME (map->l_name),
> +	     N_("cannot allocate version reference table"));
>  	  errval = ENOMEM;
>  	  goto call_error;
>  	}
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 4508365871..1c0b9cb32e 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -732,31 +732,88 @@ _dl_dprintf (int fd, const char *fmt, ...)
>    while (1)
>  
>  
> -/* This function is called by all the internal dynamic linker functions
> -   when they encounter an error.  ERRCODE is either an `errno' code or
> -   zero; OBJECT is the name of the problematical shared object, or null if
> -   it is a general problem; ERRSTRING is a string describing the specific
> -   problem.  */
> +/* An exception raised by the _dl_signal_error function family and
> +   caught by _dl_catch_error function family.  Exceptions themselves
> +   are copied as part of the raise operation, but the strings are
> +   not.  */
> +struct dl_exception
> +{
> +  const char *objname;
> +  const char *errstring;
> +
> +  /* This buffer typically stores both objname and errstring
> +     above.  */
> +  char *message_buffer;
> +};
> +
> +/* Creates a new exception.  This calls malloc; if allocation fails,
> +   dummy values are inserted.  OBJECT is the name of the problematical
> +   shared object, or null if its a general problem.  ERRSTRING is a
> +   string describing the specific problem.  */
> +void _dl_exception_create (struct dl_exception *, const char *object,
> +			   const char *errstring)
> +  __attribute__ ((nonnull (1, 3)));
> +rtld_hidden_proto (_dl_exception_create)
> +
> +/* Like _dl_exception_create, but create errstring from a format
> +   string FMT.  Currently, only "%s" and "%%" are supported as format
> +   directives.  */
> +void _dl_exception_create_format (struct dl_exception *, const char *objname,
> +				  const char *fmt, ...)
> +  __attribute__ ((nonnull (1, 3), format (printf, 3, 4)));
> +rtld_hidden_proto (_dl_exception_create_format)
> +
> +/* Deallocate the exception, freeing allocated buffers (if
> +   possible).  */
> +void _dl_exception_free (struct dl_exception *)
> +  __attribute__ ((nonnull (1)));
> +rtld_hidden_proto (_dl_exception_free)
> +
> +/* This function is called by all the internal dynamic linker
> +   functions when they encounter an error.  ERRCODE is either an
> +   `errno' code or zero; it specifies the return value of
> +   _dl_catch_error.  OCCASION is included in the error message if the
> +   process is terminated immediately.  */
> +void _dl_signal_exception (int errcode, struct dl_exception *,
> +			   const char *occasion)
> +  __attribute__ ((__noreturn__));
> +libc_hidden_proto (_dl_signal_exception)
> +
> +/* Like _dl_signal_exception, but creates the exception first.  */
>  extern void _dl_signal_error (int errcode, const char *object,
> -			      const char *occurred, const char *errstring)
> +			      const char *occasion, const char *errstring)
>       internal_function __attribute__ ((__noreturn__));
>  libc_hidden_proto (_dl_signal_error)
>  
> -/* Like _dl_signal_error, but may return when called in the context of
> -   _dl_receive_error.  This is only used during ld.so bootstrap.  In
> -   static and profiled builds, this is equivalent to
> -   _dl_signal_error.  */
> +/* Like _dl_signal_exception, but may return when called in the
> +   context of _dl_receive_error.  This is only used during ld.so
> +   bootstrap.  In static and profiled builds, this is equivalent to
> +   _dl_signal_exception.  */
> +#if IS_IN (rtld)
> +extern void _dl_signal_cexception (int errcode, struct dl_exception *,
> +				   const char *occasion) attribute_hidden;
> +#else
> +__attribute__ ((always_inline))
> +static inline void
> +_dl_signal_cexception (int errcode, struct dl_exception *exception,
> +		       const char *occasion)
> +{
> +  _dl_signal_exception (errcode, exception, occasion);
> +}
> +#endif
> +
> +/* See _dl_signal_cexception above.  */
>  #if IS_IN (rtld)
>  extern void _dl_signal_cerror (int errcode, const char *object,
> -			       const char *occation, const char *errstring)
> +			       const char *occasion, const char *errstring)
>       internal_function attribute_hidden;
>  #else
>  __attribute__ ((always_inline))
>  static inline void
>  _dl_signal_cerror (int errcode, const char *object,
> -			       const char *occation, const char *errstring)
> +			       const char *occasion, const char *errstring)
>  {
> -  _dl_signal_error (errcode, object, occation, errstring);
> +  _dl_signal_error (errcode, object, occasion, errstring);
>  }
>  #endif
>  

OK.

> @@ -768,20 +825,28 @@ extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
>  			       void *args)
>       internal_function attribute_hidden;
>  
> -/* Call OPERATE, catching errors from `dl_signal_error'.  If there is no
> -   error, *ERRSTRING is set to null.  If there is an error, *ERRSTRING is
> -   set to a string constructed from the strings passed to _dl_signal_error,
> -   and the error code passed is the return value and *OBJNAME is set to
> -   the object name which experienced the problems.  ERRSTRING if nonzero
> -   points to a malloc'ed string which the caller has to free after use.
> -   ARGS is passed as argument to OPERATE.  MALLOCEDP is set to true only
> -   if the returned string is allocated using the libc's malloc.  */
> +/* Call OPERATE, catching errors from `_dl_signal_error' and related
> +   functions.  If there is no error, *ERRSTRING is set to null.  If
> +   there is an error, *ERRSTRING is set to a string constructed from
> +   the strings passed to _dl_signal_error, and the error code passed
> +   is the return value and *OBJNAME is set to the object name which
> +   experienced the problems.  ERRSTRING if nonzero points to a
> +   malloc'ed string which the caller has to free after use.  ARGS is
> +   passed as argument to OPERATE.  MALLOCEDP is set to true only if
> +   the returned string is allocated using the libc's malloc.  */
>  extern int _dl_catch_error (const char **objname, const char **errstring,
>  			    bool *mallocedp, void (*operate) (void *),
>  			    void *args)
>       internal_function;

OK.

>  libc_hidden_proto (_dl_catch_error)
>  
> +/* Call OPERATE (ARGS).  If no error occurs, set *EXCEPTION to zero.
> +   Otherwise, store a copy of the raised exception in *EXCEPTION,
> +   which has to be freed by _dl_exception_free.  */
> +int _dl_catch_exception (struct dl_exception *exception,
> +			 void (*operate) (void *), void *args);
> +libc_hidden_proto (_dl_catch_exception)
> +
>  /* Open the shared object NAME and map in its segments.
>     LOADER's DT_RPATH is used in searching for NAME.
>     If the object is already opened, returns its existing map.  */
> diff --git a/sysdeps/generic/localplt.data b/sysdeps/generic/localplt.data
> index 81c741b038..2d5c66ae28 100644
> --- a/sysdeps/generic/localplt.data
> +++ b/sysdeps/generic/localplt.data
> @@ -16,3 +16,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/aarch64/localplt.data b/sysdeps/unix/sysv/linux/aarch64/localplt.data
> index bb18ff9bb2..a60053b914 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/localplt.data
> +++ b/sysdeps/unix/sysv/linux/aarch64/localplt.data
> @@ -18,3 +18,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/alpha/localplt.data b/sysdeps/unix/sysv/linux/alpha/localplt.data
> index 1f0e3b494e..c69eb04ce5 100644
> --- a/sysdeps/unix/sysv/linux/alpha/localplt.data
> +++ b/sysdeps/unix/sysv/linux/alpha/localplt.data
> @@ -35,3 +35,5 @@ ld.so: free + RELA R_ALPHA_GLOB_DAT
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error + RELA R_ALPHA_GLOB_DAT
>  ld.so: _dl_catch_error + RELA R_ALPHA_GLOB_DAT
> +ld.so: _dl_signal_exception + RELA R_ALPHA_GLOB_DAT
> +ld.so: _dl_catch_exception + RELA R_ALPHA_GLOB_DAT
> diff --git a/sysdeps/unix/sysv/linux/arm/localplt.data b/sysdeps/unix/sysv/linux/arm/localplt.data
> index 19d3299d98..7bd541c28a 100644
> --- a/sysdeps/unix/sysv/linux/arm/localplt.data
> +++ b/sysdeps/unix/sysv/linux/arm/localplt.data
> @@ -17,3 +17,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/hppa/localplt.data b/sysdeps/unix/sysv/linux/hppa/localplt.data
> index db9e24b090..3279c0af05 100644
> --- a/sysdeps/unix/sysv/linux/hppa/localplt.data
> +++ b/sysdeps/unix/sysv/linux/hppa/localplt.data
> @@ -21,3 +21,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/i386/localplt.data b/sysdeps/unix/sysv/linux/i386/localplt.data
> index 8ea4333846..f6f20a5d15 100644
> --- a/sysdeps/unix/sysv/linux/i386/localplt.data
> +++ b/sysdeps/unix/sysv/linux/i386/localplt.data
> @@ -16,3 +16,5 @@ ld.so: free + REL R_386_GLOB_DAT
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error + REL R_386_GLOB_DAT
>  ld.so: _dl_catch_error + REL R_386_GLOB_DAT
> +ld.so: _dl_signal_exception + REL R_386_GLOB_DAT
> +ld.so: _dl_catch_exception + REL R_386_GLOB_DAT
> diff --git a/sysdeps/unix/sysv/linux/ia64/localplt.data b/sysdeps/unix/sysv/linux/ia64/localplt.data
> index fd2b98c8b6..3820e2a4e6 100644
> --- a/sysdeps/unix/sysv/linux/ia64/localplt.data
> +++ b/sysdeps/unix/sysv/linux/ia64/localplt.data
> @@ -15,3 +15,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/m68k/localplt.data b/sysdeps/unix/sysv/linux/m68k/localplt.data
> index 1a2acfdb93..c70d6ea301 100644
> --- a/sysdeps/unix/sysv/linux/m68k/localplt.data
> +++ b/sysdeps/unix/sysv/linux/m68k/localplt.data
> @@ -15,3 +15,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/microblaze/localplt.data b/sysdeps/unix/sysv/linux/microblaze/localplt.data
> index ca476bedd8..8ca23897df 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/localplt.data
> +++ b/sysdeps/unix/sysv/linux/microblaze/localplt.data
> @@ -16,3 +16,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/nios2/localplt.data b/sysdeps/unix/sysv/linux/nios2/localplt.data
> index b0d6dcae55..4430a5891e 100644
> --- a/sysdeps/unix/sysv/linux/nios2/localplt.data
> +++ b/sysdeps/unix/sysv/linux/nios2/localplt.data
> @@ -36,3 +36,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/localplt.data b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/localplt.data
> index 50006317c7..e822e0a480 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/localplt.data
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/localplt.data
> @@ -14,3 +14,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/localplt.data b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/localplt.data
> index 1c20d2f2b4..fead931d4e 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/localplt.data
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/localplt.data
> @@ -44,3 +44,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/localplt.data b/sysdeps/unix/sysv/linux/powerpc/powerpc64/localplt.data
> index 6f8ed25922..c1209336d2 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/localplt.data
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/localplt.data
> @@ -13,3 +13,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/s390/localplt.data b/sysdeps/unix/sysv/linux/s390/localplt.data
> index 50006317c7..e822e0a480 100644
> --- a/sysdeps/unix/sysv/linux/s390/localplt.data
> +++ b/sysdeps/unix/sysv/linux/s390/localplt.data
> @@ -14,3 +14,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/sh/localplt.data b/sysdeps/unix/sysv/linux/sh/localplt.data
> index f1f5effc24..2753547d97 100644
> --- a/sysdeps/unix/sysv/linux/sh/localplt.data
> +++ b/sysdeps/unix/sysv/linux/sh/localplt.data
> @@ -19,3 +19,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data b/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data
> index 2f6ff3c3a6..1668f4017e 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data
> @@ -26,3 +26,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data b/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data
> index 912bd1a16e..b881b9096d 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data
> @@ -27,3 +27,5 @@ ld.so: free
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error
>  ld.so: _dl_catch_error
> +ld.so: _dl_signal_exception
> +ld.so: _dl_catch_exception
> diff --git a/sysdeps/x86_64/localplt.data b/sysdeps/x86_64/localplt.data
> index a1840cff31..c27a02b66a 100644
> --- a/sysdeps/x86_64/localplt.data
> +++ b/sysdeps/x86_64/localplt.data
> @@ -18,3 +18,5 @@ ld.so: free + RELA R_X86_64_GLOB_DAT
>  # The TLS-enabled version of these functions is interposed from libc.so.
>  ld.so: _dl_signal_error + RELA R_X86_64_GLOB_DAT
>  ld.so: _dl_catch_error + RELA R_X86_64_GLOB_DAT
> +ld.so: _dl_signal_exception + RELA R_X86_64_GLOB_DAT
> +ld.so: _dl_catch_exception + RELA R_X86_64_GLOB_DAT

OK.