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linux-next/scripts/tools-support-relr.sh

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arm64: Add support for relocating the kernel with RELR relocations RELR is a relocation packing format for relative relocations. The format is described in a generic-abi proposal: https://groups.google.com/d/topic/generic-abi/bX460iggiKg/discussion The LLD linker can be instructed to pack relocations in the RELR format by passing the flag --pack-dyn-relocs=relr. This patch adds a new config option, CONFIG_RELR. Enabling this option instructs the linker to pack vmlinux's relative relocations in the RELR format, and causes the kernel to apply the relocations at startup along with the RELA relocations. RELA relocations still need to be applied because the linker will emit RELA relative relocations if they are unrepresentable in the RELR format (i.e. address not a multiple of 2). Enabling CONFIG_RELR reduces the size of a defconfig kernel image with CONFIG_RANDOMIZE_BASE by 3.5MB/16% uncompressed, or 550KB/5% compressed (lz4). Signed-off-by: Peter Collingbourne <pcc@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-01 09:18:42 +08:00
#!/bin/sh -eu
# SPDX-License-Identifier: GPL-2.0
tmp_file=$(mktemp)
trap "rm -f $tmp_file.o $tmp_file $tmp_file.bin" EXIT
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: 5cf896fb6be3 ("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>
2019-11-12 21:45:20 +08:00
cat << "END" | $CC -c -x c - -o $tmp_file.o >/dev/null 2>&1
arm64: Add support for relocating the kernel with RELR relocations RELR is a relocation packing format for relative relocations. The format is described in a generic-abi proposal: https://groups.google.com/d/topic/generic-abi/bX460iggiKg/discussion The LLD linker can be instructed to pack relocations in the RELR format by passing the flag --pack-dyn-relocs=relr. This patch adds a new config option, CONFIG_RELR. Enabling this option instructs the linker to pack vmlinux's relative relocations in the RELR format, and causes the kernel to apply the relocations at startup along with the RELA relocations. RELA relocations still need to be applied because the linker will emit RELA relative relocations if they are unrepresentable in the RELR format (i.e. address not a multiple of 2). Enabling CONFIG_RELR reduces the size of a defconfig kernel image with CONFIG_RANDOMIZE_BASE by 3.5MB/16% uncompressed, or 550KB/5% compressed (lz4). Signed-off-by: Peter Collingbourne <pcc@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-01 09:18:42 +08:00
void *p = &p;
END
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: 5cf896fb6be3 ("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>
2019-11-12 21:45:20 +08:00
$LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr -o $tmp_file
arm64: Add support for relocating the kernel with RELR relocations RELR is a relocation packing format for relative relocations. The format is described in a generic-abi proposal: https://groups.google.com/d/topic/generic-abi/bX460iggiKg/discussion The LLD linker can be instructed to pack relocations in the RELR format by passing the flag --pack-dyn-relocs=relr. This patch adds a new config option, CONFIG_RELR. Enabling this option instructs the linker to pack vmlinux's relative relocations in the RELR format, and causes the kernel to apply the relocations at startup along with the RELA relocations. RELA relocations still need to be applied because the linker will emit RELA relative relocations if they are unrepresentable in the RELR format (i.e. address not a multiple of 2). Enabling CONFIG_RELR reduces the size of a defconfig kernel image with CONFIG_RANDOMIZE_BASE by 3.5MB/16% uncompressed, or 550KB/5% compressed (lz4). Signed-off-by: Peter Collingbourne <pcc@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-01 09:18:42 +08:00
# 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.
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: 5cf896fb6be3 ("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>
2019-11-12 21:45:20 +08:00
test -z "$($NM $tmp_file 2>&1 >/dev/null)"
arm64: Add support for relocating the kernel with RELR relocations RELR is a relocation packing format for relative relocations. The format is described in a generic-abi proposal: https://groups.google.com/d/topic/generic-abi/bX460iggiKg/discussion The LLD linker can be instructed to pack relocations in the RELR format by passing the flag --pack-dyn-relocs=relr. This patch adds a new config option, CONFIG_RELR. Enabling this option instructs the linker to pack vmlinux's relative relocations in the RELR format, and causes the kernel to apply the relocations at startup along with the RELA relocations. RELA relocations still need to be applied because the linker will emit RELA relative relocations if they are unrepresentable in the RELR format (i.e. address not a multiple of 2). Enabling CONFIG_RELR reduces the size of a defconfig kernel image with CONFIG_RANDOMIZE_BASE by 3.5MB/16% uncompressed, or 550KB/5% compressed (lz4). Signed-off-by: Peter Collingbourne <pcc@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-01 09:18:42 +08:00
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: 5cf896fb6be3 ("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>
2019-11-12 21:45:20 +08:00
$OBJCOPY -O binary $tmp_file $tmp_file.bin
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