[SCM] glibc maintenance branch, t/pie-sbrk, updated. glibc-2.23-4065-g0bf9da2

[Samuel Thibault]

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- Log -----------------------------------------------------------------
commit 0bf9da2956ade2a7d3baccd920fcc1e23a425a07
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Wed Aug 5 23:48:58 2020 +0200

    hurd: Rework sbrk
    
    Making the brk start exactly at the end of the main application binary was
    requiring to get it through the _end symbol, which does not work any more
    with recent toolchains, and actually produces in libc.so a confusing
    external _end symbol that produces odd results, see
    https://sourceware.org/bugzilla/show_bug.cgi?id=23499
    
    Trying to do so is quite outdated anyway with the tendency for address
    randomization.
    
    Using _end was also allowing to include the main binary data within
    the RLIMIT_DATA, but this also seems outdated with dynamic library
    loading, and nowadays' memory consumption via malloc and mmap rather than
    statically-allocated data.
    
    This adds a BRK_START macro in <vm_param.h> that just tells where we
    want to start the brk, and thus removes the _end symbol.
    
    * sysdeps/mach/hurd/i386/vm_param.h: New file.
    * sysdeps/mach/hurd/brk.c: Use BRK_START as brk start instead of _end.
    Also ignore __data_start.
    * hurd/Versions: Remove _end symbol.
    * sysdeps/mach/hurd/i386/libc.abilist: Remove _end symbol.

-----------------------------------------------------------------------

Summary of changes:
 hurd/Versions                                           |  3 ---
 sysdeps/mach/hurd/brk.c                                 | 16 ++++++----------
 sysdeps/mach/hurd/i386/libc.abilist                     |  1 -
 .../mach/hurd/i386/vm_param.h                           | 17 ++++++++---------
 4 files changed, 14 insertions(+), 23 deletions(-)
 copy benchtests/pthread_once-source.c => sysdeps/mach/hurd/i386/vm_param.h 
(70%)


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