Re: PING: [PATCH] Add --enable-static-pie to build static PIE

["H.J. Lu" <hjl dot tools at gmail dot com>]

On 9/11/17, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Fri, Sep 1, 2017 at 10:49 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>> --enable-static-pie configures glibc to compile libc.a as PIE and
>> creates static executables as PIE.  A static position independent
>> executable (static PIE) is similar to static executable, but can be
>> loaded at any address without help from a dynamic linker.  All linker
>> input files must be compiled with -fpie or -fPIE.  "-z text" is also
>> passed to linker to prevent dynamic relocations in read-only segments.
>> It passes -static-pie to the GCC driver with the patch:
>>
>> https://gcc.gnu.org/ml/gcc-patches/2017-08/msg01455.html
>>
>> This patch requires:
>>
>> 1. Linker supports --no-dynamic-linker to remove PT_INTERP segment from
>> static PIE.
>> 2. Linker can create working static PIE.  The x86-64 linker needs the
>> fix for
>>
>> https://sourceware.org/bugzilla/show_bug.cgi?id=21782
>>
>> Binutils 2.29 or above are OK.
>>
>> Tested on i686 and x86-64.
>>
>> OK for master?
>>
>> H.J.
>> ---
>>         * Makeconfig (pic-default): Updated for --enable-static-pie.
>>         (pie-default): New for --enable-static-pie.
>>         (default-pie-ldflag): Likewise.
>>         (+link-static-before-libc): Add $(default-pie-ldflag).
>>         (+prectorT): Updated for --enable-static-pie.
>>         (+postctorT): Likewise.
>>         (CFLAGS-.o): Add $(pie-default).
>>         (CFLAGS-.op): Likewise.
>>         * config.h.in (ENABLE_STATIC_PIE): New.
>>         * configure.ac (--enable-static-pie): New configure option.
>>         (have-no-dynamic-linker): New LIBC_CONFIG_VAR.
>>         (have-static-pie): Likewise.
>>         Enable static PIE if linker supports --no-dynamic-linker.
>>         (ENABLE_STATIC_PIE): New AC_DEFINE.
>>         (enable-static-pie): New LIBC_CONFIG_VAR.
>>         * configure: Regenerated.
>>         * csu/libc-start.c (LIBC_START_MAIN): Call
>> _dl_relocate_static_pie
>>         in libc.a.
>>         * csu/libc-tls.c (__libc_setup_tls): Add main_map->l_addr to
>>         initimage.
>>         * elf/dl-support.c: Include "dynamic-link.h" and don't include
>>         "get-dynamic-info.h" for --enable-static-pie.
>>         (_dl_relocate_static_pie): New function for --enable-static-pie.
>>         (STATIC_PIE_BOOTSTRAP): New for --enable-static-pie.
>>         (RESOLVE_MAP): Likewise.
>>         * elf/dynamic-link.h (ELF_DURING_STARTUP): Also check
>>         STATIC_PIE_BOOTSTRAP.
>>         * elf/get-dynamic-info.h (elf_get_dynamic_info): Likewise.
>>         * sysdeps/generic/ldsodefs.h (_dl_relocate_static_pie): New.
>>         * sysdeps/x86_64/configure.ac: Check if linker supports static
>> PIE.
>>         * sysdeps/x86_64/configure: Regenerated.
>> ---
>>  Makeconfig                  | 20 ++++++++++--
>>  config.h.in                 |  3 ++
>>  configure                   | 78
>> +++++++++++++++++++++++++++++++++++++++++++++
>>  configure.ac                | 29 +++++++++++++++++
>>  csu/libc-start.c            |  2 ++
>>  csu/libc-tls.c              |  6 ++--
>>  elf/dl-support.c            | 39 +++++++++++++++++++++--
>>  elf/dynamic-link.h          |  2 +-
>>  elf/get-dynamic-info.h      |  6 ++--
>>  sysdeps/generic/ldsodefs.h  |  7 ++++
>>  sysdeps/x86_64/configure    | 33 +++++++++++++++++++
>>  sysdeps/x86_64/configure.ac | 22 +++++++++++++
>>  12 files changed, 237 insertions(+), 10 deletions(-)
>>
>> diff --git a/Makeconfig b/Makeconfig
>> index b51904b797..b45209fe5f 100644
>> --- a/Makeconfig
>> +++ b/Makeconfig
>> @@ -386,6 +386,16 @@ LDFLAGS.so += $(hashstyle-LDFLAGS)
>>  LDFLAGS-rtld += $(hashstyle-LDFLAGS)
>>  endif
>>
>> +ifeq (yes,$(enable-static-pie))
>> +pic-default = -DPIC
>> +pie-default = $(pie-ccflag)
>> +ifeq (yes,$(have-static-pie))
>> +default-pie-ldflag = -static-pie
>> +else
>> +default-pie-ldflag = -Wl,-pie,--no-dynamic-linker,--eh-frame-hdr,-z,text
>> +endif
>> +endif
>> +
>>  # If lazy relocations are disabled, add the -z now flag.  Use
>>  # LDFLAGS-lib.so instead of LDFLAGS.so, to avoid adding the flag to
>>  # test modules.
>> @@ -435,6 +445,7 @@ endif
>>  # Command for statically linking programs with the C library.
>>  ifndef +link-static
>>  +link-static-before-libc = $(CC) -nostdlib -nostartfiles -static -o $@ \
>> +             $(default-pie-ldflag) \
>>               $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F))  \
>>               $(addprefix $(csu-objpfx),$(static-start-installed-name)) \
>>               $(+preinit) $(+prectorT) \
>> @@ -651,8 +662,13 @@ endif
>>  +prectorS = `$(CC) $(sysdep-LDFLAGS) --print-file-name=crtbeginS.o`
>>  +postctorS = `$(CC) $(sysdep-LDFLAGS) --print-file-name=crtendS.o`
>>  # Variants of the two previous definitions for statically linking
>> programs.
>> +ifeq (yes,$(enable-static-pie))
>> ++prectorT = $(+prectorS)
>> ++postctorT = $(+postctorS)
>> +else
>>  +prectorT = `$(CC) $(sysdep-LDFLAGS) --print-file-name=crtbeginT.o`
>>  +postctorT = `$(CC) $(sysdep-LDFLAGS) --print-file-name=crtend.o`
>> +endif
>>  csu-objpfx = $(common-objpfx)csu/
>>  elf-objpfx = $(common-objpfx)elf/
>>
>> @@ -973,7 +989,7 @@ libtypes = $(foreach
>> o,$(object-suffixes-for-libc),$(libtype$o))
>>  all-object-suffixes := .o .os .oS
>>  object-suffixes :=
>>  CPPFLAGS-.o = $(pic-default)
>> -CFLAGS-.o = $(filter %frame-pointer,$(+cflags))
>> +CFLAGS-.o = $(filter %frame-pointer,$(+cflags)) $(pie-default)
>>  libtype.o := lib%.a
>>  object-suffixes += .o
>>  ifeq (yes,$(build-shared))
>> @@ -998,7 +1014,7 @@ ifeq (yes,$(build-profile))
>>  all-object-suffixes += .op
>>  object-suffixes += .op
>>  CPPFLAGS-.op = -DPROF $(pic-default)
>> -CFLAGS-.op = -pg
>> +CFLAGS-.op = -pg $(pie-default)
>>  libtype.op = lib%_p.a
>>  endif
>>
>> diff --git a/config.h.in b/config.h.in
>> index 014fb4ea0e..26ed7865ef 100644
>> --- a/config.h.in
>> +++ b/config.h.in
>> @@ -236,6 +236,9 @@
>>  /* Build glibc with tunables support.  */
>>  #define HAVE_TUNABLES 0
>>
>> +/* Define if static PIE is enabled.  */
>> +#define ENABLE_STATIC_PIE 0
>> +
>>  /* Some compiler options may now allow to use ebp in __asm__ (used
>> mainly
>>     in i386 6 argument syscall issue).  */
>>  #define CAN_USE_REGISTER_ASM_EBP 0
>> diff --git a/configure b/configure
>> index 5cb5210107..a04c59bacd 100755
>> --- a/configure
>> +++ b/configure
>> @@ -767,6 +767,7 @@ with_default_link
>>  enable_sanity_checks
>>  enable_shared
>>  enable_profile
>> +enable_static_pie
>>  enable_timezone_tools
>>  enable_hardcoded_path_in_tests
>>  enable_stackguard_randomization
>> @@ -1424,6 +1425,7 @@ Optional Features:
>>                            in special situations) [default=yes]
>>    --enable-shared         build shared library [default=yes if GNU ld]
>>    --enable-profile        build profiled library [default=no]
>> +  --enable-static-pie     build static executables as PIE [default=no]
>>    --disable-timezone-tools
>>                            do not install timezone tools
>> [default=install]
>>    --enable-hardcoded-path-in-tests
>> @@ -3372,6 +3374,13 @@ else
>>    profile=no
>>  fi
>>
>> +# Check whether --enable-static-pie was given.
>> +if test "${enable_static_pie+set}" = set; then :
>> +  enableval=$enable_static_pie; static_pie=$enableval
>> +else
>> +  static_pie=no
>> +fi
>> +
>>  # Check whether --enable-timezone-tools was given.
>>  if test "${enable_timezone_tools+set}" = set; then :
>>    enableval=$enable_timezone_tools; enable_timezone_tools=$enableval
>> @@ -5994,6 +6003,62 @@ fi
>>  $as_echo "$libc_linker_feature" >&6; }
>>
>>
>> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that
>> supports --no-dynamic-linker" >&5
>> +$as_echo_n "checking for linker that supports --no-dynamic-linker... "
>> >&6; }
>> +libc_linker_feature=no
>> +if test x"$gnu_ld" = x"yes"; then
>> +  libc_linker_check=`$LD -v --help 2>/dev/null | grep
>> "\--no-dynamic-linker"`
>> +  if test -n "$libc_linker_check"; then
>> +    cat > conftest.c <<EOF
>> +int _start (void) { return 42; }
>> +EOF
>> +    if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
>> +                               -Wl,--no-dynamic-linker -nostdlib
>> -nostartfiles
>> +                               -fPIC -shared -o conftest.so conftest.c
>> +                               1>&5'
>> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
>> +  (eval $ac_try) 2>&5
>> +  ac_status=$?
>> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
>> +  test $ac_status = 0; }; }
>> +    then
>> +      libc_linker_feature=yes
>> +    fi
>> +    rm -f conftest*
>> +  fi
>> +fi
>> +if test $libc_linker_feature = yes; then
>> +  libc_cv_no_dynamic_linker=yes
>> +else
>> +  libc_cv_no_dynamic_linker=no
>> +fi
>> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature"
>> >&5
>> +$as_echo "$libc_linker_feature" >&6; }
>> +config_vars="$config_vars
>> +have-no-dynamic-linker = $libc_cv_no_dynamic_linker"
>> +
>> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for -static-pie" >&5
>> +$as_echo_n "checking for -static-pie... " >&6; }
>> +if ${libc_cv_static_pie+:} false; then :
>> +  $as_echo_n "(cached) " >&6
>> +else
>> +  if { ac_try='${CC-cc} -static-pie -xc /dev/null -S -o /dev/null'
>> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
>> +  (eval $ac_try) 2>&5
>> +  ac_status=$?
>> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
>> +  test $ac_status = 0; }; }; then :
>> +  libc_cv_static_pie=yes
>> +else
>> +  libc_cv_static_pie=no
>> +fi
>> +
>> +fi
>> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_static_pie"
>> >&5
>> +$as_echo "$libc_cv_static_pie" >&6; }
>> +config_vars="$config_vars
>> +have-static-pie = $libc_cv_static_pie"
>> +
>>  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -fpie" >&5
>>  $as_echo_n "checking for -fpie... " >&6; }
>>  if ${libc_cv_fpie+:} false; then :
>> @@ -6888,6 +6953,19 @@ fi
>>  $as_echo "$libc_cv_pie_default" >&6; }
>>
>>
>> +if test "$static_pie" = yes; then
>> +  # The linker must support --no-dynamic-linker.
>> +  if test "$libc_cv_no_dynamic_linker" != yes; then
>> +    as_fn_error $? "linker support for --no-dynamic-linker needed"
>> "$LINENO" 5
>> +  fi
>> +  # Default to PIE.
>> +  libc_cv_pie_default=yes
>> +  $as_echo "#define ENABLE_STATIC_PIE 1" >>confdefs.h
>> +
>> +fi
>> +config_vars="$config_vars
>> +enable-static-pie = $static_pie"
>> +
>>
>>
>>
>> diff --git a/configure.ac b/configure.ac
>> index 2c6308883c..96af835ce8 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -176,6 +176,11 @@ AC_ARG_ENABLE([profile],
>>                              [build profiled library
>> @<:@default=no@:>@]),
>>               [profile=$enableval],
>>               [profile=no])
>> +AC_ARG_ENABLE([static-pie],
>> +             AC_HELP_STRING([--enable-static-pie],
>> +                            [build static executables as PIE
>> @<:@default=no@:>@]),
>> +             [static_pie=$enableval],
>> +             [static_pie=no])
>>  AC_ARG_ENABLE([timezone-tools],
>>               AC_HELP_STRING([--disable-timezone-tools],
>>                              [do not install timezone tools
>> @<:@default=install@:>@]),
>> @@ -1460,6 +1465,19 @@ LIBC_LINKER_FEATURE([-z execstack],
>> [-Wl,-z,execstack],
>>                     [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no])
>>  AC_SUBST(libc_cv_z_execstack)
>>
>> +LIBC_LINKER_FEATURE([--no-dynamic-linker],
>> +                   [-Wl,--no-dynamic-linker],
>> +                   [libc_cv_no_dynamic_linker=yes],
>> +                   [libc_cv_no_dynamic_linker=no])
>> +LIBC_CONFIG_VAR([have-no-dynamic-linker], [$libc_cv_no_dynamic_linker])
>> +
>> +AC_CACHE_CHECK(for -static-pie, libc_cv_static_pie, [dnl
>> +LIBC_TRY_CC_OPTION([-static-pie],
>> +                  [libc_cv_static_pie=yes],
>> +                  [libc_cv_static_pie=no])
>> +])
>> +LIBC_CONFIG_VAR([have-static-pie], [$libc_cv_static_pie])
>> +
>>  AC_CACHE_CHECK(for -fpie, libc_cv_fpie, [dnl
>>  LIBC_TRY_CC_OPTION([-fpie], [libc_cv_fpie=yes], [libc_cv_fpie=no])
>>  ])
>> @@ -1962,6 +1980,17 @@ fi
>>  rm -f conftest.*])
>>  AC_SUBST(libc_cv_pie_default)
>>
>> +if test "$static_pie" = yes; then
>> +  # The linker must support --no-dynamic-linker.
>> +  if test "$libc_cv_no_dynamic_linker" != yes; then
>> +    AC_MSG_ERROR([linker support for --no-dynamic-linker needed])
>> +  fi
>> +  # Default to PIE.
>> +  libc_cv_pie_default=yes
>> +  AC_DEFINE(ENABLE_STATIC_PIE)
>> +fi
>> +LIBC_CONFIG_VAR([enable-static-pie], [$static_pie])
>> +
>>  AC_SUBST(profile)
>>  AC_SUBST(static_nss)
>>
>> diff --git a/csu/libc-start.c b/csu/libc-start.c
>> index 24c63be02f..34dd125260 100644
>> --- a/csu/libc-start.c
>> +++ b/csu/libc-start.c
>> @@ -141,6 +141,8 @@ LIBC_START_MAIN (int (*main) (int, char **, char **
>> MAIN_AUXVEC_DECL),
>>    __libc_multiple_libcs = &_dl_starting_up && !_dl_starting_up;
>>
>>  #ifndef SHARED
>> +  _dl_relocate_static_pie ();
>> +
>>    char **ev = &argv[argc + 1];
>>
>>    __environ = ev;
>> diff --git a/csu/libc-tls.c b/csu/libc-tls.c
>> index 00138eb43a..1f8ddaf543 100644
>> --- a/csu/libc-tls.c
>> +++ b/csu/libc-tls.c
>> @@ -114,6 +114,8 @@ __libc_setup_tls (void)
>>    size_t tcb_offset;
>>    const ElfW(Phdr) *phdr;
>>
>> +  struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
>> +
>>    /* Look through the TLS segment if there is any.  */
>>    if (_dl_phdr != NULL)
>>      for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)
>> @@ -122,7 +124,7 @@ __libc_setup_tls (void)
>>           /* Remember the values we need.  */
>>           memsz = phdr->p_memsz;
>>           filesz = phdr->p_filesz;
>> -         initimage = (void *) phdr->p_vaddr;
>> +         initimage = (void *) phdr->p_vaddr + main_map->l_addr;
>>           align = phdr->p_align;
>>           if (phdr->p_align > max_align)
>>             max_align = phdr->p_align;
>> @@ -163,8 +165,6 @@ __libc_setup_tls (void)
>>    _dl_static_dtv[0].counter = (sizeof (_dl_static_dtv) / sizeof
>> (_dl_static_dtv[0])) - 2;
>>    // _dl_static_dtv[1].counter = 0;            would be needed if not
>> already done
>>
>> -  struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
>> -
>>    /* Initialize the TLS block.  */
>>  #if TLS_TCB_AT_TP
>>    _dl_static_dtv[2].pointer.val = ((char *) tlsblock + tcb_offset
>> diff --git a/elf/dl-support.c b/elf/dl-support.c
>> index 48340f7959..09b2229d48 100644
>> --- a/elf/dl-support.c
>> +++ b/elf/dl-support.c
>> @@ -26,7 +26,11 @@
>>  #include <sys/param.h>
>>  #include <stdint.h>
>>  #include <ldsodefs.h>
>> -#include <dl-machine.h>
>> +#if ENABLE_STATIC_PIE
>> +# include "dynamic-link.h"
>> +#else
>> +# include <dl-machine.h>
>> +#endif
>>  #include <libc-lock.h>
>>  #include <dl-cache.h>
>>  #include <dl-librecon.h>
>> @@ -199,7 +203,9 @@ const ElfW(Ehdr) *_dl_sysinfo_dso;
>>
>>  struct link_map *_dl_sysinfo_map;
>>
>> -# include "get-dynamic-info.h"
>> +# if !ENABLE_STATIC_PIE
>> +#  include "get-dynamic-info.h"
>> +# endif
>>  #endif
>>  #include "setup-vdso.h"
>>
>> @@ -303,6 +309,35 @@ _dl_aux_init (ElfW(auxv_t) *av)
>>  }
>>  #endif
>>
>> +#if ENABLE_STATIC_PIE
>> +/* Relocate static executable with PIE.  */
>> +
>> +void
>> +_dl_relocate_static_pie (void)
>> +{
>> +# define STATIC_PIE_BOOTSTRAP
>> +# define RESOLVE_MAP(sym, version, flags) (&_dl_main_map)
>> +# include "dynamic-link.h"
>> +
>> +  /* Figure out the run-time load addres of static PIE.  */
>> +  _dl_main_map.l_addr = elf_machine_load_address ();
>> +
>> +  /* Read our own dynamic section and fill in the info array.  */
>> +  _dl_main_map.l_ld = ((void *) _dl_main_map.l_addr
>> +                      + elf_machine_dynamic ());
>> +  elf_get_dynamic_info (&_dl_main_map, NULL);
>> +
>> +# ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
>> +  ELF_MACHINE_BEFORE_RTLD_RELOC (_dl_main_map.l_info);
>> +# endif
>> +
>> +  /* Relocate ourselves so we can do normal function calls and
>> +     data access using the global offset table.  */
>> +  ELF_DYNAMIC_RELOCATE (&_dl_main_map, 0, 0, 0);
>> +  _dl_main_map.l_relocated = 1;
>> +}
>> +#endif
>> +
>>
>>  void
>>  internal_function
>> diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h
>> index 60f2d91151..d3935f7da7 100644
>> --- a/elf/dynamic-link.h
>> +++ b/elf/dynamic-link.h
>> @@ -95,7 +95,7 @@ elf_machine_lazy_rel (struct link_map *map,
>>
>>  #ifdef RESOLVE_MAP
>>
>> -# ifdef RTLD_BOOTSTRAP
>> +# if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP
>>  #  define ELF_DURING_STARTUP (1)
>>  # else
>>  #  define ELF_DURING_STARTUP (0)
>> diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h
>> index 7525c3a5b2..eb26d23649 100644
>> --- a/elf/get-dynamic-info.h
>> +++ b/elf/get-dynamic-info.h
>> @@ -38,7 +38,7 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn)
>> *temp)
>>    typedef Elf64_Xword d_tag_utype;
>>  #endif
>>
>> -#ifndef RTLD_BOOTSTRAP
>> +#if !defined RTLD_BOOTSTRAP && !defined STATIC_PIE_BOOTSTRAP
>>    if (dyn == NULL)
>>      return;
>>  #endif
>> @@ -139,9 +139,11 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn)
>> *temp)
>>    /* Only the bind now flags are allowed.  */
>>    assert (info[VERSYMIDX (DT_FLAGS_1)] == NULL
>>           || (info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val & ~DF_1_NOW) ==
>> 0);
>> +  /* Flags must not be set for ld.so.  */
>>    assert (info[DT_FLAGS] == NULL
>>           || (info[DT_FLAGS]->d_un.d_val & ~DF_BIND_NOW) == 0);
>> -  /* Flags must not be set for ld.so.  */
>> +#endif
>> +#if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP
>>    assert (info[DT_RUNPATH] == NULL);
>>    assert (info[DT_RPATH] == NULL);
>>  #else
>> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
>> index 49e673dd24..83791103cf 100644
>> --- a/sysdeps/generic/ldsodefs.h
>> +++ b/sysdeps/generic/ldsodefs.h
>> @@ -1069,6 +1069,13 @@ extern void _dl_determine_tlsoffset (void)
>> internal_function attribute_hidden;
>>     stack protector, among other things).  */
>>  void __libc_setup_tls (void);
>>
>> +# if ENABLE_STATIC_PIE
>> +/* Relocate static executable with PIE.  */
>> +void _dl_relocate_static_pie (void) attribute_hidden;
>> +# else
>> +#  define _dl_relocate_static_pie()
>> +# endif
>> +
>>  /* Initialization of libpthread for statically linked applications.
>>     If libpthread is not linked in, this is an empty function.  */
>>  void __pthread_initialize_minimal (void) weak_function;
>> diff --git a/sysdeps/x86_64/configure b/sysdeps/x86_64/configure
>> index efef46b1b7..8ee15b8a25 100644
>> --- a/sysdeps/x86_64/configure
>> +++ b/sysdeps/x86_64/configure
>> @@ -85,6 +85,39 @@ if test x"$build_mathvec" = xnotset; then
>>    build_mathvec=yes
>>  fi
>>
>> +if test "$static_pie" = yes; then
>> +  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker static PIE
>> support" >&5
>> +$as_echo_n "checking for linker static PIE support... " >&6; }
>> +if ${libc_cv_ld_static_pie+:} false; then :
>> +  $as_echo_n "(cached) " >&6
>> +else
>> +  cat > conftest.s <<\EOF
>> +       .text
>> +       .global _start
>> +       .weak foo
>> +_start:
>> +       leaq    foo(%rip), %rax
>> +EOF
>> +  libc_cv_pie_option="-Wl,-pie"
>> +  if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostartfiles
>> -nostdlib $no_ssp $libc_cv_pie_option conftest.s 1>&5'
>> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
>> +  (eval $ac_try) 2>&5
>> +  ac_status=$?
>> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
>> +  test $ac_status = 0; }; }; then
>> +    libc_cv_ld_static_pie=yes
>> +  else
>> +    libc_cv_ld_static_pie=no
>> +  fi
>> +rm -f conftest*
>> +fi
>> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ld_static_pie"
>> >&5
>> +$as_echo "$libc_cv_ld_static_pie" >&6; }
>> +  if test "$libc_cv_ld_static_pie" != yes; then
>> +    as_fn_error $? "linker support for static PIE needed" "$LINENO" 5
>> +  fi
>> +fi
>> +
>>  $as_echo "#define PI_STATIC_AND_HIDDEN 1" >>confdefs.h
>>
>>
>> diff --git a/sysdeps/x86_64/configure.ac b/sysdeps/x86_64/configure.ac
>> index fa86e953ee..c2d7cf3e61 100644
>> --- a/sysdeps/x86_64/configure.ac
>> +++ b/sysdeps/x86_64/configure.ac
>> @@ -44,6 +44,28 @@ if test x"$build_mathvec" = xnotset; then
>>    build_mathvec=yes
>>  fi
>>
>> +dnl Check if linker supports static PIE.
>> +if test "$static_pie" = yes; then
>> +  AC_CACHE_CHECK(for linker static PIE support, libc_cv_ld_static_pie,
>> [dnl
>> +cat > conftest.s <<\EOF
>> +       .text
>> +       .global _start
>> +       .weak foo
>> +_start:
>> +       leaq    foo(%rip), %rax
>> +EOF
>> +  libc_cv_pie_option="-Wl,-pie"
>> +  if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostartfiles
>> -nostdlib $no_ssp $libc_cv_pie_option conftest.s 1>&AS_MESSAGE_LOG_FD);
>> then
>> +    libc_cv_ld_static_pie=yes
>> +  else
>> +    libc_cv_ld_static_pie=no
>> +  fi
>> +rm -f conftest*])
>> +  if test "$libc_cv_ld_static_pie" != yes; then
>> +    AC_MSG_ERROR([linker support for static PIE needed])
>> +  fi
>> +fi
>> +
>>  dnl It is always possible to access static and hidden symbols in an
>>  dnl position independent way.
>>  AC_DEFINE(PI_STATIC_AND_HIDDEN)
>> --
>> 2.13.5
>>
>
> Any comments?
>

Any objections?

-- 
H.J.