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From:   Heiko Carstens <hca@linux.ibm.com>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Ulrich Weigand <Ulrich.Weigand@de.ibm.com>,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] s390/decompresser: fix misaligned symbol build error
Date:   Thu, 22 Jun 2023 14:55:08 +0200
Message-Id: <20230622125508.1068457-1-hca@linux.ibm.com>
Content-Transfer-Encoding: 8bit
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Nathan Chancellor reported a kernel build error on Fedora 39:

$ clang --version | head -1
clang version 16.0.5 (Fedora 16.0.5-1.fc39)

$ s390x-linux-gnu-ld --version | head -1
GNU ld version 2.40-1.fc39

$ make -skj"$(nproc)" ARCH=s390 CC=clang CROSS_COMPILE=s390x-linux-gnu- olddefconfig all
s390x-linux-gnu-ld: arch/s390/boot/startup.o(.text+0x5b4): misaligned symbol `_decompressor_end' (0x35b0f) for relocation R_390_PC32DBL
make[3]: *** [.../arch/s390/boot/Makefile:78: arch/s390/boot/vmlinux] Error 1

It turned out that the problem with misaligned symbols on s390 was fixed
with commit 80ddf5ce1c92 ("s390: always build relocatable kernel") for the
kernel image, but did not take into account that the decompressor uses its
own set of CFLAGS, which come without -fPIE.

Add the -fPIE flag also to the decompresser CFLAGS to fix this.

Reported-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1747
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index ed646c583e4f..5ed242897b0d 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -27,6 +27,7 @@ KBUILD_CFLAGS_DECOMPRESSOR += -fno-delete-null-pointer-checks -msoft-float -mbac
 KBUILD_CFLAGS_DECOMPRESSOR += -fno-asynchronous-unwind-tables
 KBUILD_CFLAGS_DECOMPRESSOR += -ffreestanding
 KBUILD_CFLAGS_DECOMPRESSOR += -fno-stack-protector
+KBUILD_CFLAGS_DECOMPRESSOR += -fPIE
 KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
-- 
2.39.2