[Bug dynamic-link/21598] i386 _dl_runtime_resolve/_dl_runtime_profile is incompatible with shadow stack

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

https://sourceware.org/bugzilla/show_bug.cgi?id=21598

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=63f003ec3d687be1425f859e44104719b3df6b5e

commit 63f003ec3d687be1425f859e44104719b3df6b5e
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Dec 6 12:59:01 2017 -0800

    Replace xorq with xorl

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0be1e91808872b93a5e7cb3b46cc5f316012b141

commit 0be1e91808872b93a5e7cb3b46cc5f316012b141
Author: Igor Tsimbalist <igor.v.tsimbalist@intel.com>
Date:   Wed Dec 6 16:36:48 2017 +0300

    Add shadow stack pointer processing for Intel CET.

        * i386/____longjmp_chk.S: Add ssp adjustment.
        * i386/__longjmp.S: Likewise.
        * i386/setjmp.S: Add spp saving.
        * x86_64/____longjmp_chk.S: Add ssp adjustment.
        * x86_64/__longjmp.S: Likewise.
        * x86_64/setjmp.S: Add spp saving.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=59f53f3dc799b43faffe8f4d541c1c1eb9447e7f

commit 59f53f3dc799b43faffe8f4d541c1c1eb9447e7f
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Tue Dec 5 11:58:23 2017 -0800

    Linux/x86: Copy setjmp/longjmp for SHSTK

    TODO: Add SHSTK support to

    sysdeps/unix/sysv/linux/i386/____longjmp_chk.S
    sysdeps/unix/sysv/linux/i386/__longjmp.S
    sysdeps/unix/sysv/linux/i386/bsd-_setjmp.S
    sysdeps/unix/sysv/linux/i386/bsd-setjmp.S
    sysdeps/unix/sysv/linux/i386/setjmp.S
    sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S
    sysdeps/unix/sysv/linux/x86_64/__longjmp.S
    sysdeps/unix/sysv/linux/x86_64/setjmp.S

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=58a87a71a877b173667f5e9b5960303db031807a

commit 58a87a71a877b173667f5e9b5960303db031807a
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Jun 22 04:15:39 2017 -0700

    x86: Support IBT and SHSTK in Intel CET [BZ #21598]

    Intel Control-flow Enforcement Technology (CET) instructions:

   
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-en
    forcement-technology-preview.pdf

    includes Indirect Branch Tracking (IBT) and Shadow Stack (SHSTK).

    GNU_PROPERTY_X86_FEATURE_1_IBT is added to GNU program property to
    indicate that all executable sections are compatible with IBT when
    ENDBR instruction starts each valid target where an indirect branch
    instruction can land.  Linker sets GNU_PROPERTY_X86_FEATURE_1_IBT on
    output only if it is set on all relocatable inputs.

    On an IBT capable processor, the following steps should be taken:

    1. When loading an executable without an interpreter, enable IBT and
    lock IBT if GNU_PROPERTY_X86_FEATURE_1_IBT is set on the executable.
    2. When loading an executable with an interpreter, enable IBT if
    GNU_PROPERTY_X86_FEATURE_1_IBT is set on the interpreter.
      a. If GNU_PROPERTY_X86_FEATURE_1_IBT isn't set on the executable,
         disable IBT.
      b. Lock IBT.
    3. If IBT is enabled, when loading a shared object without
    GNU_PROPERTY_X86_FEATURE_1_IBT:
      a. If legacy interwork is allowed, then mark all pages in executable
         PT_LOAD segments in legacy code page bitmap.  Failure of legacy code
         page bitmap allocation causes an error.
      b. If legacy interwork isn't allowed, it causes an error.

    GNU_PROPERTY_X86_FEATURE_1_SHSTK is added to GNU program property to
    indicate that all executable sections are compatible with SHSTK where
    return address popped from shadow stack always matches return address
    popped from normal stack.  Linker sets GNU_PROPERTY_X86_FEATURE_1_SHSTK
    on output only if it is set on all relocatable inputs.

    On a SHSTK capable processor, the following steps should be taken:

    1. When loading an executable without an interpreter, enable SHSTK if
    GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on the executable.
    2. When loading an executable with an interpreter, enable SHSTK if
    GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on interpreter.
      a. If GNU_PROPERTY_X86_FEATURE_1_SHSTK isn't set on the executable
         or any shared objects loaded via the DT_NEEDED tag, disable SHSTK.
      b. Otherwise lock SHSTK.
    3. After SHSTK is enabled, it is an error to load a shared object
    without GNU_PROPERTY_X86_FEATURE_1_SHSTK.

    When glibc is built with a CET-enabled compiler, CET is enabled by
    default, unless --disable-cet is used to configure glibc.  When CET is
    enabled, both compiler and assembler must support CET.  Otherwise, it
    is a configure-time error.

    To support CET run-time control,

    1. _dl_x86_feature_1 is added to the writable ld.so namespace to indicate
    if IBT or SHSTK are enabled at run-time.  It should be initialized by
    init_cpu_features.
    2. For dynamic executables:
       a. A l_cet field is added to struct link_map to indicate if IBT or
          SHSTK is enabled in an ELF module.  The optional DL_PROCESS_PT_NOTE
          is called to process PT_NOTE segment for GNU program property and
          set l_cet.
       b. _dl_start_user calls _dl_cet_init, instead of _dl_init, which sets
          up IBT and SHSTK.
       c. DL_OPEN_CHECK is added to check IBT and SHSTK compatibilty when
          dlopening a shared object.
    3. Replace i386 _dl_runtime_resolve and _dl_runtime_profile with
    _dl_runtime_resolve_shstk and _dl_runtime_profile_shstk, respectively if
    SHSTK is enabled.

    <cet.h> from CET-enabled GCC is automatically included by assembly codes
    to add GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK
    to GNU program property.  _CET_ENDBR is added at the entrance of all
    assembly functions whose address may be taken.

         [BZ #21598]
        * config.h.in (ENABLE_CET): New #undef.
        * configure.ac: Add --enable-cet.
        * configure: Regenerated.
        * elf/dl-load.c (filebuf): Moved before "dynamic-link.h".
        (_dl_map_object_from_fd): Call DL_PROCESS_PT_NOTE on PT_NOTE
        segment if DL_PROCESS_PT_NOTE is defined.
        * elf/rtld.c (dl_main): Likewise.
        * elf/dl-open.c (dl_open_worker): Call DL_OPEN_CHECK if it is
        defined.
        * elf/dl-support.c: Include <dl-procruntime.c>.
        * include/link.h: Include <link_map.h>.
        * sysdeps/generic/dl-procruntime.c: New file.
        * sysdeps/generic/link_map.h: Likewise.
        * sysdeps/unix/sysv/linux/i386/dl-cet.c: Likewise.
        * sysdeps/unix/sysv/linux/i386/dl-machine.h: Likewise.
        * sysdeps/unix/sysv/linux/x86/check-cet.awk: Likewise.
        * sysdeps/unix/sysv/linux/x86/configure: Likewise.
        * sysdeps/unix/sysv/linux/x86/configure.ac: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-cet.c: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-cet.h: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-procruntime.c: Likewise.
        * sysdeps/unix/sysv/linux/x86/link_map.h: Likewise.
        * sysdeps/unix/sysv/linux/x86_64/dl-machine.h: Likewise.
        * sysdeps/generic/ldsodefs.h: Include <dl-procruntime.c> in
        the writable ld.so namespace.
        * sysdeps/i386/dl-machine.h (DL_INIT): New.
        (_dl_start_user): Replace _dl_init with DL_INIT.
        * sysdeps/i386/dl-trampoline.S (_dl_runtime_resolve): Add
        _CET_ENDBR.
        (_dl_runtime_profile): Likewise.
        (_dl_runtime_resolve_shstk): New.
        (_dl_runtime_profile_shstk): Likewise.
        * sysdeps/unix/sysv/linux/x86/Makefile (sysdep_routines): Add
        dl-cet-nonshared if CET is enabled.
        (sysdep-dl-routines): Add dl-cet if CET is enabled.
        (CFLAGS-.o): Add -fcf-protection -mcet if CET is enabled.
        (CFLAGS-.os): Likewise.
        (CFLAGS-.op): Likewise.
        (CFLAGS-.oS): Likewise.
        (asm-CPPFLAGS): Add -fcf-protection -mcet -include cet.h if CET
        is enabled.
        (tests-special): Add $(objpfx)check-cet.out.
        (cet-built-dso): New.
        (+$(cet-built-dso:=.note)): Likewise.
        (common-generated): Add $(cet-built-dso:$(common-objpfx)%=%.note).
        ($(objpfx)check-cet.out): New.
        (generated): Add check-cet.out.
        * sysdeps/x86/sysdep.h (_CET_ENDBR): Define if not defined.
        (ENTRY): Add _CET_ENDBR.
        * sysdeps/x86_64/dl-machine.h (DL_INIT): New.
        (_dl_start_user): Replace _dl_init with DL_INIT.
        * sysdeps/x86_64/x32/dl-machine.h (_dl_start_user): Likewise.
        * sysdeps/x86_64/dl-trampoline.h (_dl_runtime_resolve): Add
        _CET_ENDBR.
        (_dl_runtime_profile): Likewise.

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