On Wed, May 11, 2022 at 5:05 AM Heiko Carstens <hca@xxxxxxxxxxxxx> wrote:
>
> A couple of patches which in result make it finally possible to build the
> kernel for s390 with llvm's integrated assembler. Several configs build
> without errors or warnings, and the kernel also works as expected.
>
> Note that patch 6 ("s390/boot: workaround llvm IAS bug") reveals a
> miscompile. This looks like a bug in the instruction definitions of the mvc
> and clc instructions(?). I'd like to ask people to look into this, since
> this silently generated broken code.
>
> This patch series is based on linux-next, which contains two additional
> required s390 specific patches to make llvm's IAS work.
I did a quick test of just a defconfig via:
$ ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- make CC=clang -j72 defconfig all
and this assembled then booted in qemu for me. Thanks for the work
that went into this!
Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Sounds like Nathan is doing additional testing as well.
>
> Thanks,
> Heiko
>
> Heiko Carstens (8):
> s390/alternatives: provide identical sized orginal/alternative sequences
> s390/alternatives: remove padding generation code
> s390/entry: shorten OUTSIDE macro
> s390/entry: workaround llvm's IAS limitations
> s390/purgatory: workaround llvm's IAS limitations
> s390/boot: workaround llvm IAS bug
> s390/boot: do not emit debug info for assembly with llvm's IAS
> scripts/min-tool-version.sh: raise minimum clang version to 14.0.0 for s390
>
> arch/s390/Makefile | 2 +
> arch/s390/boot/head.S | 34 +++++----
> arch/s390/include/asm/alternative-asm.h | 76 +++-----------------
> arch/s390/include/asm/alternative.h | 93 ++++++-------------------
> arch/s390/include/asm/spinlock.h | 2 +-
> arch/s390/kernel/alternative.c | 61 +---------------
> arch/s390/kernel/entry.S | 39 +++++++----
> arch/s390/lib/spinlock.c | 4 +-
> arch/s390/purgatory/head.S | 29 ++++++--
> scripts/min-tool-version.sh | 3 +-
> 10 files changed, 104 insertions(+), 239 deletions(-)
>
> --
> 2.32.0
>
--
Thanks,
~Nick Desaulniers
