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From:   Alexandre Ghiti <alexghiti@rivosinc.com>
Date:   Thu, 2 Feb 2023 16:13:35 +0100
Message-ID: <CAHVXubjeSMvfTPnvrnYRupOGx6+vUvUGfRS3piTeo=TH2cHKNg@mail.gmail.com>
Subject: Re: [PATCH v4 0/1] riscv: Allow to downgrade paging mode from the
 command line
To:     Conor Dooley <conor@kernel.org>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Ard Biesheuvel <ardb@kernel.org>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
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On Thu, Feb 2, 2023 at 4:07 PM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
>
> Hi Conor,
>
> On Tue, Jan 31, 2023 at 8:25 PM Conor Dooley <conor@kernel.org> wrote:
> >
> > Hey Alex,
> >
> > On Tue, Jan 31, 2023 at 04:11:14PM +0100, Alexandre Ghiti wrote:
> > > This new version gets rid of the limitation that prevented KASAN kernels
> > > to use the newly introduced parameters.
> >
> > What's the base commit for this version?

And to answer your question: this patch applies nicely on top of
v6.2-rc6 + my KASAN patchset
(https://patchwork.kernel.org/project/linux-riscv/list/?series=715388)

> > Fails to apply for me on top of for-next, fixes, rc1, and linux-next :/
> > I also tried it on top of your KASAN series, but no luck there either!
>
> Really sorry about that, that's the second time it happens, I'll
> improve my workflow: I'll include the base-commit sha1/tag + a link to
> all needed-but-not-yet-upstreamed patches.
>
> Thanks for your time,
>
> Alex
>
> >
> > Thanks,
> > Conor.
> >
> > > While looking into KASLR, I fell onto commit aacd149b6238 ("arm64: head:
> > > avoid relocating the kernel twice for KASLR"): it allows to use the fdt
> > > functions very early in the boot process with KASAN enabled by simply
> > > compiling a new version of those functions without instrumentation.
> > >
> > > I had to change the handling of the command line parsing to make the
> > > code self-contained in kernel/pi/cmd_early.c to avoid calling too many
> > > __pi prefixed functions from outside this file.
> > >
> > > I'll use this approach like arm64 to handle the extraction of the random
> > > seedi from the device tree for KASLR.
> > >
> > > @Ard: I copied the "pi" name but I have to admit I don't know what it
> > > means.
> > >
> > > Alexandre Ghiti (1):
> > >   riscv: Allow to downgrade paging mode from the command line
> > >
> > >  .../admin-guide/kernel-parameters.txt         |  5 +-
> > >  arch/riscv/kernel/Makefile                    |  2 +
> > >  arch/riscv/kernel/pi/Makefile                 | 34 ++++++++++++
> > >  arch/riscv/kernel/pi/cmdline_early.c          | 52 +++++++++++++++++++
> > >  arch/riscv/lib/memcpy.S                       |  2 +
> > >  arch/riscv/lib/memmove.S                      |  2 +
> > >  arch/riscv/mm/init.c                          | 36 ++++++++++---
> > >  7 files changed, 126 insertions(+), 7 deletions(-)
> > >  create mode 100644 arch/riscv/kernel/pi/Makefile
> > >  create mode 100644 arch/riscv/kernel/pi/cmdline_early.c
> > >
> > > --
> > > 2.37.2
> > >