linux-kernel - Re: [PATCH] riscv: Fix SMP when shadow call stacks are enabled

Open Source and information security mailing list archives

Date:   Thu, 7 Dec 2023 20:50:05 -0500
From:   Guo Ren <guoren@...nel.org>
To:     Sami Tolvanen <samitolvanen@...gle.com>
Cc:     Samuel Holland <samuel.holland@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        linux-riscv@...ts.infradead.org, Albert Ou <aou@...s.berkeley.edu>,
        Andy Chiu <andy.chiu@...ive.com>,
        Clément Léger <cleger@...osinc.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Greentime Hu <greentime.hu@...ive.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nam Cao <namcaov@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: Fix SMP when shadow call stacks are enabled

On Fri, Dec 01, 2023 at 09:40:55AM -0800, Sami Tolvanen wrote:
> Hi Samuel,
> 
> On Tue, Nov 21, 2023 at 1:20 PM Samuel Holland
> <samuel.holland@...ive.com> wrote:
> >
> > This fixes two bugs in SCS initialization for secondary CPUs. First,
> > the SCS was not initialized at all in the spinwait boot path. Second,
> > the code for the SBI HSM path attempted to initialize the SCS before
> > enabling the MMU. However, that involves dereferencing the thread
> > pointer, which requires the MMU to be enabled.
> >
> > Fix both issues by setting up the SCS in the common secondary entry
> > path, after enabling the MMU.
> 
> Thanks for the patch! Looks like my qemu setup doesn't hit this issue,
> but nevertheless, the fix looks good to me.
Because there is no function call in relocate_enable_mmu :)

> 
> Reviewed-by: Sami Tolvanen <samitolvanen@...gle.com>
> 
> Sami
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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