From: Ard Biesheuvel <ardb@kernel.org>
To: Guillaume Tucker <guillaume.tucker@collabora.com>
Cc: "kernelci-results@groups.io" <kernelci-results@groups.io>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Nicolas Pitre <nico@fluxnic.net>,
Linus Walleij <linus.walleij@linaro.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Russell King - ARM Linux admin <linux@armlinux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: next/master bisection: baseline.login on rk3288-rock2-square
Date: Fri, 5 Feb 2021 13:05:54 +0100 [thread overview]
Message-ID: <CAMj1kXGrABn7KxSPxTo3pWJEk3fNsN-zBBHZkbVfg7gTavL_pQ@mail.gmail.com> (raw)
In-Reply-To: <CAMj1kXFKzEPqG5j2bn5n_3imc9aFyOEHX7CVDdwe2=ugTq=bZQ@mail.gmail.com>
On Fri, 5 Feb 2021 at 09:21, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Thu, 4 Feb 2021 at 22:31, Guillaume Tucker
> <guillaume.tucker@collabora.com> wrote:
> >
> > On 04/02/2021 18:23, Nick Desaulniers wrote:
> > > On Thu, Feb 4, 2021 at 10:12 AM Nathan Chancellor <nathan@kernel.org> wrote:
> > >>
> > >> On Thu, Feb 04, 2021 at 10:06:08AM -0800, 'Nick Desaulniers' via Clang Built Linux wrote:
> > >>> On Thu, Feb 4, 2021 at 8:02 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> > >>>>
> > >>>> On Thu, 4 Feb 2021 at 16:53, Guillaume Tucker
> > >>>> <guillaume.tucker@collabora.com> wrote:
> > >>>>>
> > >>>>> On 04/02/2021 15:42, Ard Biesheuvel wrote:
> > >>>>>> On Thu, 4 Feb 2021 at 12:32, Guillaume Tucker
> > >>>>>> <guillaume.tucker@collabora.com> wrote:
> > >>>>>>>
> > >>>>>>> Essentially:
> > >>>>>>>
> > >>>>>>> make -j18 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- LLVM=1 CC="ccache clang" zImage
> > >>>
> > >>> This command should link with BFD (and assemble with GAS; it's only
> > >>> using clang as the compiler.
> > >>
> > >> I think you missed the 'LLVM=1' before CC="ccache clang". That should
> > >> use all of the LLVM utilities minus the integrated assembler while
> > >> wrapping clang with ccache.
> > >
> > > You're right, I missed `LLVM=1`. Adding `LD=ld.bfd` I think should
> > > permit fallback to BFD.
> >
> > That was close, except we're cross-compiling with GCC for arm.
> > So I've now built a plain next-20210203 (without Ard's fix) using
> > this command line:
> >
> > make LD=arm-linux-gnueabihf-ld.bfd -j18 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- LLVM=1 CC="ccache clang" zImage
> >
> > I'm using a modified Docker image gtucker/kernelci-build-clang-11
> > with the very latest LLVM 11 and gcc-8-arm-linux-gnueabihf
> > packages added to be able to use the GNU linker. BTW I guess we
> > should enable this kind of hybrid build setup on kernelci.org as
> > well.
> >
> > Full build log + kernel binaries can be found here:
> >
> > https://storage.staging.kernelci.org/gtucker/next-20210203-ard-fix/v5.10-rc4-24722-g58b6c0e507b7-gtucker_single-staging-41/arm/multi_v7_defconfig/clang-11/
> >
> > And this booted fine, which confirms it's really down to how
> > ld.lld puts together the kernel image. Does it actually solve
> > the debate whether this is an issue to fix in the assembly code
> > or at link time?
> >
> > Full test job details for the record:
> >
> > https://lava.collabora.co.uk/scheduler/job/3176004
> >
>
>
> So the issue appears to be in the way the linker generates the
> _kernel_bss_size symbol, which obviously has an impact, given that the
> queued fix takes it into account in the cache_clean operation.
>
> On GNU ld, I see
>
> 479: 00065e14 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size
>
> whereas n LLVM ld.lld, I see
>
> 433: c1c86e98 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size
>
> and adding this value may cause the cache clean to operate on unmapped
> addresses, or cause the addition to wrap and not perform a cache clean
> at all.
>
> AFAICT, this also breaks the appended DTB case in LLVM, so this needs
> a separate fix in any case.
I pushed a combined branch of torvalds/master, rmk/fixes (still
containing my 9052/1 fix) and this patch to my for-kernelci branch
https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/
Guillaume,
It seems there is no Clang-11 coverage there, right? Mind giving this
branch a spin? If this fixes the regressions, we can get these queued
up.
Thanks,
Ard.
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next prev parent reply other threads:[~2021-02-05 12:07 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <601b773a.1c69fb81.9f381.a32a@mx.google.com>
2021-02-04 8:43 ` next/master bisection: baseline.login on rk3288-rock2-square Guillaume Tucker
2021-02-04 9:07 ` Ard Biesheuvel
2021-02-04 10:06 ` Russell King - ARM Linux admin
2021-02-04 10:27 ` Ard Biesheuvel
2021-02-04 10:33 ` Guillaume Tucker
2021-02-04 11:32 ` Guillaume Tucker
2021-02-04 11:44 ` Russell King - ARM Linux admin
2021-02-04 12:09 ` Ard Biesheuvel
2021-02-04 15:42 ` Ard Biesheuvel
2021-02-04 15:53 ` Guillaume Tucker
2021-02-04 16:01 ` Ard Biesheuvel
2021-02-04 18:06 ` Nick Desaulniers
2021-02-04 18:12 ` Nathan Chancellor
2021-02-04 18:23 ` Nick Desaulniers
2021-02-04 21:31 ` Guillaume Tucker
2021-02-04 21:50 ` Russell King - ARM Linux admin
2021-02-05 8:21 ` Ard Biesheuvel
2021-02-05 12:05 ` Ard Biesheuvel [this message]
2021-02-06 13:10 ` Guillaume Tucker
2021-02-06 13:12 ` Ard Biesheuvel
2021-02-04 21:09 ` Guillaume Tucker
2021-02-04 10:47 ` Russell King - ARM Linux admin
2021-02-04 10:55 ` Ard Biesheuvel
2021-02-04 12:26 ` Marc Zyngier
2021-02-04 14:09 ` Russell King - ARM Linux admin
2021-02-04 14:25 ` Ard Biesheuvel
2021-02-04 14:36 ` Russell King - ARM Linux admin
2021-02-04 15:52 ` Ard Biesheuvel
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