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From:   Greentime Hu <green.hu@gmail.com>
Date:   Wed, 11 Dec 2019 16:42:33 +0800
Message-ID: <CAEbi=3e4dzDex=zU2Bwvi+b=Jwz2NsT4fZPcT_o8umnJaub3Mg@mail.gmail.com>
Subject: Re: RISC-V nommu support v6
To:     Paul Walmsley <paul.walmsley@sifive.com>
Cc:     Christoph Hellwig <hch@lst.de>, Palmer Dabbelt <palmer@sifive.com>,
        Damien Le Moal <damien.lemoal@wdc.com>,
        linux-riscv@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Paul Walmsley <paul.walmsley@sifive.com> =E6=96=BC 2019=E5=B9=B411=E6=9C=88=
23=E6=97=A5 =E9=80=B1=E5=85=AD =E4=B8=8A=E5=8D=8810:24=E5=AF=AB=E9=81=93=EF=
=BC=9A
>
> On Thu, 31 Oct 2019, Christoph Hellwig wrote:
>
> > On Wed, Oct 30, 2019 at 01:21:21PM -0700, Paul Walmsley wrote:
> > > I tried building this series from your git branch mentioned above, an=
d
> > > booted it with a buildroot userspace built from your custom buildroot
> > > tree.  Am seeing some segmentation faults from userspace (below).
> > >
> > > Am still planning to merge your patches.
> > >
> > > But I'm wondering whether you are seeing these segmentation faults al=
so?
> > > Or is it something that might be specific to my test setup?
> >
> > I just built a fresh image using make -j4 with that report and it works
> > perfectly fine with my tree.
>
> Another colleague just gave this a quick test, following your instruction=
s
> as I did.  He encountered the same segmentation faulting issue.  Might be
> worth taking a look at this once v5.5-rc1 is released.  Could be a
> userspace issue, though.

Hi Christoph,

I think it should be replaced with this macro for cores without S-mode.

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 9bca97ffb67a..5c8b24bf4e4e 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -248,7 +248,7 @@ ENTRY(reset_regs)
        li      t4, 0
        li      t5, 0
        li      t6, 0
-       csrw    sscratch, 0
+       csrw    CSR_SCRATCH, 0

 #ifdef CONFIG_FPU
        csrr    t0, CSR_MISA