[ Upstream commit f3304ecd7f ]
Since commit 7b4537199a ("kbuild: link symbol CRCs at final link,
removing CONFIG_MODULE_REL_CRCS"), the module versioning on the
(non-upstreamed-yet) kvx Linux port is broken due to unexpected padding
for __crc_* symbols. The kvx GCC adds padding so u32 gets 8-byte
alignment instead of 4.
I do not know if this happens for upstream architectures in general,
but any compiler has the freedom to insert padding for faster access.
Use the inline assembler to directly specify the wanted data layout.
This is how we previously did before the breakage.
Link: https://lore.kernel.org/lkml/20220817161438.32039-1-ysionneau@kalray.eu/
Link: https://lore.kernel.org/linux-kbuild/31ce5305-a76b-13d7-ea55-afca82c46cf2@kalray.eu/
Fixes: 7b4537199a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS")
Reported-by: Yann Sionneau <ysionneau@kalray.eu>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Yann Sionneau <ysionneau@kalray.eu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
include/{linux,asm-generic}/export.h defines a weak symbol, __crc_*
as a placeholder.
Genksyms writes the version CRCs into the linker script, which will be
used for filling the __crc_* symbols. The linker script format depends
on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset
to the reference of CRC.
It is time to get rid of this complexity.
Now that modpost parses text files (.*.cmd) to collect all the CRCs,
it can generate C code that will be linked to the vmlinux or modules.
Generate a new C file, .vmlinux.export.c, which contains the CRCs of
symbols exported by vmlinux. It is compiled and linked to vmlinux in
scripts/link-vmlinux.sh.
Put the CRCs of symbols exported by modules into the existing *.mod.c
files. No additional build step is needed for modules. As before,
*.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal.
No linker magic is used here. The new C implementation works in the
same way, whether CONFIG_RELOCATABLE is enabled or not.
CONFIG_MODULE_REL_CRCS is no longer needed.
Previously, Kbuild invoked additional $(LD) to update the CRCs in
objects, but this step is unneeded too.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)