linux/scripts/tools-support-relr.sh
Ilie Halip 65e1f38d9a scripts/tools-support-relr.sh: un-quote variables
When the CC variable contains quotes, e.g. when using
ccache (make CC="ccache <compiler>"), this script always
fails, so CONFIG_RELR is never enabled, even when the
toolchain supports this feature. Removing the /dev/null
redirect and invoking the script manually shows the issue:

    $ CC='/usr/bin/ccache clang' ./scripts/tools-support-relr.sh
    ./scripts/tools-support-relr.sh: 7: ./scripts/tools-support-relr.sh: /usr/bin/ccache clang: not found

Fix this by un-quoting the variables.

Before:
    $ make ARCH=arm64 CC='/usr/bin/ccache clang' LD=ld.lld \
        NM=llvm-nm OBJCOPY=llvm-objcopy defconfig
    $ grep RELR .config
    CONFIG_ARCH_HAS_RELR=y

With this change:
    $ make ARCH=arm64 CC='/usr/bin/ccache clang' LD=ld.lld \
        NM=llvm-nm OBJCOPY=llvm-objcopy defconfig
    $ grep RELR .config
    CONFIG_TOOLS_SUPPORT_RELR=y
    CONFIG_ARCH_HAS_RELR=y
    CONFIG_RELR=y

Fixes: 5cf896fb6b ("arm64: Add support for relocating the kernel with RELR relocations")
Reported-by: Dmitry Golovin <dima@golovin.in>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/769
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Will Deacon <will@kernel.org>
2019-11-13 10:52:05 +00:00

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#!/bin/sh -eu
# SPDX-License-Identifier: GPL-2.0
tmp_file=$(mktemp)
trap "rm -f $tmp_file.o $tmp_file $tmp_file.bin" EXIT
cat << "END" | $CC -c -x c - -o $tmp_file.o >/dev/null 2>&1
void *p = &p;
END
$LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr -o $tmp_file
# Despite printing an error message, GNU nm still exits with exit code 0 if it
# sees a relr section. So we need to check that nothing is printed to stderr.
test -z "$($NM $tmp_file 2>&1 >/dev/null)"
$OBJCOPY -O binary $tmp_file $tmp_file.bin