arm crypto .S_shipped files sometimes get rebuilt randomly
Masahiro Yamada
yamada.masahiro at socionext.com
Wed Mar 7 21:00:03 PST 2018
2018-03-08 4:25 GMT+09:00 Leonard Crestez <leonard.crestez at nxp.com>:
> Hello,
>
> I am using a toolchain with a broken/old version of perl which doesn't
> include integer.pm and I noticed it triggers occasional build failures
> on arch/arm64/crypto/sha512-core.S_shipped. Workarounds are easy, but
> if the purpose of the .S_shipped is to avoid the need to have all
> dependencies on the build machine then something went wrong?
>
> This was introduced by commit 7918ecef073f ("crypto: arm64/sha2 -
> integrate OpenSSL implementations of SHA256/SHA512"). The makefile
> rules are not terribly complicated:
>
> quiet_cmd_perlasm = PERLASM $@
> cmd_perlasm = $(PERL) $(<) void $(@)
>
> $(src)/sha512-core.S_shipped: $(src)/sha512-armv8.pl
> $(call cmd,perlasm)
>
> If a decision to rerun the rule is made based on their relative
> timestamps but both .S_shipped and sha512-armv8.pl are included in git
> then won't the result be essentially random, depending on file checkout
> order?
>
> I see random success/failure by just running something like the
> following multiple times:
> rm -rf arch/arm64/crypto
> git co -f arch/arm64/crypto
> make -- arch/arm64/crypto/
>
> A reasonable fix might be to simply drop .S_shipped and require a
> functional recent version of perl. Then if it fails it will fail
> reliably.
>
Indeed, this Makefile is weird.
We have two choices.
[1] If we intend to generate
sha{256,512}-core.S from the perl script during the build,
this should be:
$(obj)/sha512-core.S: $(src)/sha512-armv8.pl
$(call cmd,perlasm)
$(obj)/sha512-core.S: $(src)/sha512-armv8.pl
$(call cmd,perlasm)
[2] If we want to check-in _shipped files
and avoid running perl during the build,
we can surround unnecessary rules with if-conditional, like
if REGENERATE_ARM64_SHA
$(src)/sha256-core.S_shipped: $(src)/sha512-armv8.pl
$(call cmd,perlasm)
$(src)/sha512-core.S_shipped: $(src)/sha512-armv8.pl
$(call cmd,perlasm)
endif
Set REGENERATE_ARM64_SHA=1 from the command line
only when you need to update the _shipped files.
This is what commit 7373f4f83c71d50f0aece6d94309ab7fde42180f did.
Recently, Kconfig switched to [1].
So, flex and bison are required to build the kernel.
--
Best Regards
Masahiro Yamada
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