zstd decompression uses __builtin_clz() which fails back to __clzdi2() when the kernel is built for older hardware like z900. This leads to build failures like the following: s390x-11.1.0-ld: /devel/src/kernel/arch/s390/boot/compressed/../../../../lib/zstd/bitstream.h:148: undefined reference to `__clzdi2' Fix that by optionally including lib/clz_ctz.c into the decompressor. Reported-by: kernel test robot Fixes: 7b034d9c1b08 ("s390/boot: add zstd support") Signed-off-by: Vasily Gorbik --- arch/s390/boot/compressed/Makefile | 1 + arch/s390/boot/compressed/clz_ctz.c | 2 ++ 2 files changed, 3 insertions(+) create mode 100644 arch/s390/boot/compressed/clz_ctz.c diff --git a/arch/s390/boot/compressed/Makefile b/arch/s390/boot/compressed/Makefile index 660c799d875d..e30d3fdbbc78 100644 --- a/arch/s390/boot/compressed/Makefile +++ b/arch/s390/boot/compressed/Makefile @@ -11,6 +11,7 @@ UBSAN_SANITIZE := n KASAN_SANITIZE := n obj-y := $(if $(CONFIG_KERNEL_UNCOMPRESSED),,decompressor.o) info.o +obj-$(CONFIG_KERNEL_ZSTD) += clz_ctz.o obj-all := $(obj-y) piggy.o syms.o targets := vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 targets += vmlinux.bin.xz vmlinux.bin.lzma vmlinux.bin.lzo vmlinux.bin.lz4 diff --git a/arch/s390/boot/compressed/clz_ctz.c b/arch/s390/boot/compressed/clz_ctz.c new file mode 100644 index 000000000000..c3ebf248596b --- /dev/null +++ b/arch/s390/boot/compressed/clz_ctz.c @@ -0,0 +1,2 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "../../../../lib/clz_ctz.c" -- 2.25.4