FreeBSD/Linux Kernel Cross Reference
sys/tools/amd64_vdso.sh

     #!/bin/sh
     # SPDX-License-Identifier: BSD-2-Clause-FreeBSD
     #
     # Copyright (c) 2021 The FreeBSD Foundation
     # All rights reserved.
     #
     # This software was developed by Konstantin Belousov <kib@FreeBSD.org>
     # under sponsorship from the FreeBSD Foundation.
     #
    # Redistribution and use in source and binary forms, with or without
    # modification, are permitted provided that the following conditions
    # are met:
    # 1. Redistributions of source code must retain the above copyright
    #    notice, this list of conditions and the following disclaimer.
    # 2. Redistributions in binary form must reproduce the above copyright
    #    notice, this list of conditions and the following disclaimer in the
    #    documentation and/or other materials provided with the distribution.
    #
    # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
    # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
    # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
    # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
    # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    # SUCH DAMAGE.
    
    set -e
    
    ${CC} -x assembler-with-cpp -DLOCORE -fPIC -nostdinc -c \
       -o sigtramp.pico -I. -I"${S}" -include opt_global.h \
       "${S}"/amd64/amd64/sigtramp.S
    
    # We need to make vdso as compact as possible, for it to leave space
    # for other things in the shared page.  For this, we pack everything
    # into single loadable segment.
    #
    # -z rodynamic is undocumented lld-specific option, seemingly required
    # for lld to avoid putting dynamic into dedicated writeable segment,
    # despite ldscript placement.  It is ignored by ld.bfd but ldscript
    # alone is enough there.
    #
    ${LD} --shared -Bsymbolic -soname="elf-vdso.so.1" \
       -T "${S}"/conf/vdso_amd64.ldscript \
       --eh-frame-hdr --no-undefined -z rodynamic -z norelro -nmagic \
       --hash-style=sysv --fatal-warnings --strip-all \
       -o elf-vdso.so.1 sigtramp.pico
    
    if [ "$(wc -c elf-vdso.so.1 | ${AWK} '{print $1}')" -gt 2048 ]
    then
        echo "elf-vdso.so.1 too large" 1>&2
        exit 1
    fi
    
    if [ -n "$(${ELFDUMP} -d elf-vdso.so.1 | \
      ${AWK} '/DT_REL.*SZ/{print "RELOCS"}')" ]
    then
        echo "elf-vdso.so.1 contains runtime relocations" 1>&2
        exit 1
    fi
    
    ${CC} ${DEBUG} -x assembler-with-cpp -DLOCORE -fPIC -nostdinc -c \
       -o elf-vdso.so.o -I. -I"${S}" -include opt_global.h \
       -DVDSO_NAME=elf_vdso_so_1 -DVDSO_FILE=elf-vdso.so.1 \
       "${S}"/tools/vdso_wrap.S
    
    ${NM} -D elf-vdso.so.1 | \
       ${AWK} '/__vdso_sigcode/{printf "#define VDSO_SIGCODE_OFFSET 0x%s\n",$1}' \
       >vdso_offsets.h

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