[Bug libc/19574] glibc should support building static PIE binaries

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=19574

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The branch, hjl/pie/static has been created
        at  951b8ac9a2dd6a4a36b939b1e1f47013740e07d8 (commit)

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=951b8ac9a2dd6a4a36b939b1e1f47013740e07d8

commit 951b8ac9a2dd6a4a36b939b1e1f47013740e07d8
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Sep 27 16:47:29 2017 -0700

    Add --enable-static-pie to build-many-glibcs.py

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=42ec59f560e64d1eec0c1a9b3768ef8d0a660154

commit 42ec59f560e64d1eec0c1a9b3768ef8d0a660154
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Sep 28 16:13:54 2017 -0700

    sparc: Check PIC instead of SHARED in start.S

    Since start.o may be compiled as PIC, we should check PIC instead of
    SHARED.

        * sysdeps/sparc/sparc32/start.S (_start): Check PIC instead of
        SHARED.
        * sysdeps/sparc/sparc64/start.S (_start): Likewise.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=966d45d91d4647c62d3fccb0f7e684a676fdaced

commit 966d45d91d4647c62d3fccb0f7e684a676fdaced
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Sep 28 16:13:22 2017 -0700

    microblaze: Check PIC instead of SHARED in start.S

    Since start.o may be compiled as PIC, we should check PIC instead of
    SHARED.

        * sysdeps/microblaze/start.S (_start): Check PIC instead of SHARED.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=12df728c40440a0d8420596dcc4c7625cb8be0dd

commit 12df728c40440a0d8420596dcc4c7625cb8be0dd
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Sep 28 14:55:18 2017 -0700

    sh: Update elf_machine_load_address for static PIE

    When --enable-static-pie is used to configure glibc, we need to use
    _dl_relocate_static_pie to compute load address in static PIE.

        * sysdeps/sh/dl-machine.h (elf_machine_load_address): Use
        _dl_relocate_static_pie instead of _dl_start to compute load
        address in static PIE.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=eaa885503cf44933e959812ba6b90b600cb854d3

commit eaa885503cf44933e959812ba6b90b600cb854d3
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Sep 28 14:53:06 2017 -0700

    s390: Update elf_machine_load_address for static PIE

    When --enable-static-pie is used to configure glibc, we need to use
    _dl_relocate_static_pie to compute load address in static PIE.

        * sysdeps/s390/s390-32/dl-machine.h (elf_machine_dynamic): Use
        _dl_relocate_static_pie instead of _dl_start to compute load
        address in static PIE.
        * sysdeps/s390/s390-64/dl-machine.h (elf_machine_dynamic):
        Likewise.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b3c9432386edbd2f57098daa6a2a63780c9d9d63

commit b3c9432386edbd2f57098daa6a2a63780c9d9d63
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Jul 17 08:17:32 2017 -0700

    Add --enable-static-pie configure option to build static PIE [BZ #19574]

    Dynamic linker, ld.so, is a standalone program which can be loaded at
    any address.  This patch adds a configure option, --enable-static-pie,
    to embed the part of ld.so in static executable to create static position
    independent executable (static PIE).  A static PIE is similar to static
    executable, but can be loaded at any address without help from a dynamic
    linker.  When --enable-static-pie is used to configure glibc, libc.a is
    built as PIE and all static executables, including tests, are built as
    static PIE.  The resulting libc.a can be used together with GCC 8 or
    above to build static PIE with the compiler option, -static-pie.  But
    GCC 8 isn't required to build glibc with --enable-static-pie.  When an
    older GCC is used to build glibc with --enable-static-pie, proper input
    files are passed to linker to create static executables as static PIE,
    together with "-z text" to prevent dynamic relocations in read-only
    segments, which are allowed in static PIE.

    The following changes are made for static PIE:

    1. Add a new function, _dl_relocate_static_pie, to:
       a. Get the run-time load address.
       b. Read the dynamic section.
       c. Perform dynamic relocations.
    Dynamic linker also performs these steps.  But static PIE doesn't load
    any shared objects.
    2. Call _dl_relocate_static_pie at entrance of LIBC_START_MAIN in
    libc.a.  crt1.o, which is used to create dynamic and non-PIE static
    executables, is updated to include a dummy _dl_relocate_static_pie.
    rcrt1.o is added to create static PIE, which will link in the real
    _dl_relocate_static_pie.  grcrt1.o is also added to create static PIE
    with -pg.  GCC 8 has been updated to support rcrt1.o and grcrt1.o for
    static PIE.

    Static PIE can work on all architectures which support PIE, provided:

    1. Target must support accessing of local functions without dynamic
    relocations, which is needed in start.S to call __libc_start_main with
    function addresses of __libc_csu_init, __libc_csu_fini and main.  All
    functions in static PIE are local functions.  If PIE start.S can't reach
    main () defined in a shared object, the code sequence:

        pass addess of local_main to __libc_start_main
        ...

    local_main:
        tail call to main via PLT

    can be used.
    2. start.S is updated to check PIC instead SHARED for PIC code path and
    avoid dynamic relocation, when PIC is defined and SHARED isn't defined,
    to support static PIE.  Patches are submitted for aarch64, hppa, m68k,
    microblaze and sparc.
    3. All assembly codes are updated check PIC instead SHARED for PIC code
    path to avoid dynamic relocations in read-only sections.
    4. All assembly codes are updated check SHARED instead PIC for static
    symbol name.  A patch is submitted for tile.
    5. elf_machine_load_address in dl-machine.h are updated to support static
    PIE.  Patches are submitted for aarch64, s390 and sh.
    6. __brk works without TLS nor dynamic relocations in read-only section
    so that it can be used by __libc_setup_tls to initializes TLS in static
    PIE.

    NB: When glibc is built with GCC defaulted to PIE, libc.a is compiled
    with -fPIE, regardless if --enable-static-pie is used to configure glibc.
    When glibc is configured with --enable-static-pie, libc.a is compiled
    with -fPIE, regardless wether GCC defaults to PIE or not.  The same libc.a
    can be used to build both static executable and static PIE.  There is no
    need for separate PIE copy of libc.a.

    On x86-64, the normal static sln:

       text        data     bss     dec     hex filename
     625425        8284    5456  639165   9c0bd elf/sln

    the static PIE sln:

       text        data     bss     dec     hex filename
     657626       20636    5392  683654   a6e86 elf/sln

    The code size is increased by 5% and the binary size is increased by 7%.

    Linker requirements to build glibc with --enable-static-pie:

    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

    The i386 linker needs to be able to convert "movl main@GOT(%ebx), %eax"
    to "leal main@GOTOFF(%ebx), %eax" if main is defined locally.

    Binutils 2.29 or above are OK for i686 and x86-64.  But linker status for
    other targets need to be verified.

    3. Linker should resolve undefined weak symbols to 0 in static PIE:

    https://sourceware.org/bugzilla/show_bug.cgi?id=22269

    4. Many ELF backend linkers incorrectly check bfd_link_pic for TLS
    relocations, which should check bfd_link_executable instead:

    https://sourceware.org/bugzilla/show_bug.cgi?id=22263

    Tested on aarch64, i686 and x86-64.

    On aarch64, binutils master branch with 2 patches:

    https://sourceware.org/ml/binutils/2017-11/msg00455.html
    https://sourceware.org/ml/binutils/2017-11/msg00456.html

    applied is required.

    build-many-glibcs.py with --enable-static-pie with all patches for static
    PIE applied have many failures:

    FAIL: glibcs-alpha-linux-gnu build

    elf/sln is failed to link due to:

    assertion fail bfd/elf64-alpha.c:4125

    This is caused by linker bug and/or non-PIC code in PIE libc.a.

    FAIL: glibcs-ia64-linux-gnu build

    elf/sln is failed to link due to:

    libc.a(sched_yield.o): non-pic code with imm relocation against dynamic
symbol `_dl_sysinfo'

    This is caused by non-PIC version of DO_CALL macro in ia64 sysdep.h.  PIE
    libc.a should use PIC version of DO_CALL, except during startup in static
    PIE.  An ia64 startup.h, similar to i386 startup.h, is needed to handle
    this.

    FAIL: glibcs-mips64el-linux-gnu-n32 build
    FAIL: glibcs-mips64el-linux-gnu-n32-nan2008 build
    FAIL: glibcs-mips64el-linux-gnu-n32-nan2008-soft build
    FAIL: glibcs-mips64el-linux-gnu-n32-soft build
    FAIL: glibcs-mips64-linux-gnu-n32 build
    FAIL: glibcs-mips64-linux-gnu-n32-nan2008 build
    FAIL: glibcs-mips64-linux-gnu-n32-nan2008-soft build
    FAIL: glibcs-mips64-linux-gnu-n32-soft build
    FAIL: glibcs-mipsel-linux-gnu build
    FAIL: glibcs-mipsel-linux-gnu-nan2008 build
    FAIL: glibcs-mipsel-linux-gnu-nan2008-soft build
    FAIL: glibcs-mipsel-linux-gnu-soft build
    FAIL: glibcs-mips-linux-gnu build
    FAIL: glibcs-mips-linux-gnu-nan2008 build
    FAIL: glibcs-mips-linux-gnu-nan2008-soft build
    FAIL: glibcs-mips-linux-gnu-soft build

    elf/sln is failed to link due to:

    crt1.o: relocation R_MIPS_HI16 against `_gp' can not be used when making a
shared object; recompile with -fPIC

    This is caused by linker bug and/or non-PIC code in crt1.o.

    FAIL: glibcs-powerpc-linux-gnu build
    FAIL: glibcs-powerpc-linux-gnu-soft build
    FAIL: glibcs-powerpc-linux-gnuspe build
    FAIL: glibcs-powerpc-linux-gnuspe-e500v1 build

    elf/sln is failed to link due to:

    ld: read-only segment has dynamic relocations.

    This is caused by linker bug and/or non-PIC code in PIE libc.a.  See:

    https://sourceware.org/bugzilla/show_bug.cgi?id=22264

    FAIL: glibcs-powerpc-linux-gnu-power4 build

    elf/sln is failed to link due to:

    findlocale.c:96:(.text+0x22c): @local call to ifunc memchr

    This is caused by linker bug and/or non-PIC code in PIE libc.a.

    FAIL: glibcs-s390-linux-gnu build

    elf/sln is failed to link due to:

    collect2: fatal error: ld terminated with signal 11 [Segmentation fault],
core dumped

    assertion fail bfd/elflink.c:14242

    This is caused by linker bug and/or non-PIC code in PIE libc.a.

    FAIL: glibcs-sh3eb-linux-gnu build
    FAIL: glibcs-sh3-linux-gnu build
    FAIL: glibcs-sh4eb-linux-gnu build
    FAIL: glibcs-sh4eb-linux-gnu-soft build
    FAIL: glibcs-sh4-linux-gnu build
    FAIL: glibcs-sh4-linux-gnu-soft build

    elf/sln is failed to link due to:

    ld: read-only segment has dynamic relocations.

    This is caused by linker bug and/or non-PIC code in PIE libc.a.  See:

    https://sourceware.org/bugzilla/show_bug.cgi?id=22263

    Also TLS code sequence in SH assembly syscalls in glibc doesn't match TLS
    code sequence expected by ld:

    https://sourceware.org/bugzilla/show_bug.cgi?id=22270

    FAIL: glibcs-sparc64-linux-gnu build
    FAIL: glibcs-sparcv9-linux-gnu build
    FAIL: glibcs-tilegxbe-linux-gnu build
    FAIL: glibcs-tilegxbe-linux-gnu-32 build
    FAIL: glibcs-tilegx-linux-gnu build
    FAIL: glibcs-tilegx-linux-gnu-32 build
    FAIL: glibcs-tilepro-linux-gnu build

    elf/sln is failed to link due to:

    ld: read-only segment has dynamic relocations.

    This is caused by linker bug and/or non-PIC code in PIE libc.a.  See:

    https://sourceware.org/bugzilla/show_bug.cgi?id=22263

        [BZ #19574]
        * INSTALL: Regenerated.
        * Makeconfig (static-start-installed-name): Add the `r' prefix
        for --enable-static-pie.
        (pic-default): Updated for --enable-static-pie.
        (pie-default): New for --enable-static-pie.
        (default-pie-ldflag): Likewise.
        (+link-static-before-libc): Use the first of $(DEFAULT-LDFLAGS-$(@F))
        and $(default-pie-ldflag).
        (+prectorT): Updated for --enable-static-pie.
        (+postctorT): Likewise.
        (CFLAGS-.o): Add $(pie-default).
        (CFLAGS-.op): Likewise.
        * NEWS: Mention --enable-static-pie.
        * config.h.in (ENABLE_STATIC_PIE): New.
        * configure.ac (--enable-static-pie): New configure option.
        (have-no-dynamic-linker): New LIBC_CONFIG_VAR.
        (have-static-pie): Likewise.
        Enable static PIE if linker supports --no-dynamic-linker.
        (ENABLE_STATIC_PIE): New AC_DEFINE.
        (enable-static-pie): New LIBC_CONFIG_VAR.
        * configure: Regenerated.
        * csu/Makefile (omit-deps): Add r$(start-installed-name) for
        --enable-static-pie.
        (extra-objs): Likewise.
        (install-lib): Likewise.
        (extra-objs): Add static-reloc.o and static-reloc.os
        ($(objpfx)$(start-installed-name)): Also depend on
        $(objpfx)static-reloc.o.
        ($(objpfx)r$(start-installed-name)): New.
        ($(objpfx)g$(start-installed-name)): Also depend on
        $(objpfx)static-reloc.os.
        * csu/libc-start.c (LIBC_START_MAIN): Call _dl_relocate_static_pie
        in libc.a.
        * csu/libc-tls.c (__libc_setup_tls): Add main_map->l_addr to
        initimage.
        * csu/static-reloc.c: New file.
        * elf/Makefile (routines): Add dl-reloc-static-pie.
        (elide-routines.os): Likewise.
        * elf/dl-reloc-static-pie.c: New file.
        * elf/dl-support.c (_dl_get_dl_main_map): New function.
        * elf/dynamic-link.h (ELF_DURING_STARTUP): Also check
        STATIC_PIE_BOOTSTRAP.
        * elf/get-dynamic-info.h (elf_get_dynamic_info): Likewise.
        * gmon/Makefile (tests): Add tst-gmon-static-pie.
        (tests-static): Likewise.
        (CFLAGS-tst-gmon-static-pie.c): New.
        (CRT-tst-gmon-static-pie): Likewise.
        (tst-gmon-static-pie-ENV): Likewise.
        (tests-special): Likewise.
        ($(objpfx)tst-gmon-static-pie.out): Likewise.
        (clean-tst-gmon-static-pie-data): Likewise.
        ($(objpfx)tst-gmon-static-pie-gprof.out): Likewise.
        * gmon/tst-gmon-static-pie.c: New file.
        * manual/install.texi: Document --enable-static-pie.
        * sysdeps/generic/ldsodefs.h (_dl_relocate_static_pie): New.
        (_dl_get_dl_main_map): Likewise.
        * sysdeps/i386/configure.ac: Check if linker supports static PIE.
        * sysdeps/x86_64/configure.ac: Likewise.
        * sysdeps/i386/configure: Regenerated.
        * sysdeps/x86_64/configure: Likewise.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=3b08f0b7f94a40fd165b44a06346690f5691e77b

commit 3b08f0b7f94a40fd165b44a06346690f5691e77b
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Fri Nov 24 07:13:10 2017 -0800

    aarch64: fix start code for static pie

    with upcoming static pie patches there are three flavors of the crt startup
code:

    1) crt1.o used for non-pie static linking (executable has no relocs),
    2) Scrt1.o used for dynamic linking (dynamic linker relocates),
    3) rcrt1.o used for static pie linking (self relocation is needed)

    when crt1.o and rcrt1.o is built in the --enable-static-pie case -DPIC is
passed,
    when Scrt1.o is built then -DPIC -DSHARED is passed.

    (crt1.o gets a dummy _dl_relocate_static_pie that interposes the one in
    libc so no self-relocation is done in that case in __libc_start_main)

    the Scrt1.o code is position independent but it relies on GOT entries that
    need to be relocated which happens later and the static linker cannot relax
    the GOT loads, so rcrt1.o needs separate implementation.

    This implementation works with .text <= 4G files, which is fine, currently
    the toolchain does not support larger position independent executables.

    tests pass with ld/22269 and ld/22263 binutils bugs fixed.
    this patch is on top of master but assumes the static pie patches.

        * sysdeps/aarch64/start.S (_start): Handle PIC && !SHARED case.

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