linux-kernel - Re: [RFC PATCH V4 1/6] riscv: pgtable: Add custom protection

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJF2gTQ0Nbb7QCFjKdY223eHQjeV3_05Ub3N3LM7hvY38gizsg@mail.gmail.com>
Date:   Thu, 16 Sep 2021 07:52:09 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Anup Patel <anup.patel@....com>, Atish Patra <atish.patra@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Christoph Müllner <christoph.muellner@...ll.eu>,
        Philipp Tomsich <philipp.tomsich@...ll.eu>,
        liush <liush@...winnertech.com>, wefu@...hat.com,
        Wei Wu (吴伟) <lazyparser@...il.com>,
        Drew Fustini <drew@...gleboard.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        taiten.peng@...onical.com, aniket.ponkshe@...onical.com,
        heinrich.schuchardt@...onical.com, gordan.markus@...onical.com,
        Guo Ren <guoren@...ux.alibaba.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Palmer Dabbelt <palmer@...belt.com>
Subject: Re: [RFC PATCH V4 1/6] riscv: pgtable: Add custom protection_map init

Hi Christoph,

On Wed, Sep 15, 2021 at 3:46 PM Christoph Hellwig <hch@....de> wrote:
>
> On Sat, Sep 11, 2021 at 05:21:34PM +0800, guoren@...nel.org wrote:
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > Some RISC-V CPU vendors have defined their own PTE attributes to
> > solve non-coherent DMA bus problems. That makes _P/SXXX definitions
> > contain global variables which could be initialized at the early
> > boot stage before setup_vm. The patch prevents compile errors.
>
> That sounds way to nice for someone who deliberatly ignores the
> specification and should definitively not go into the kernel
> commit log like this.
Okay. In the next version, I will optimize the wording.

>
> > This patch is similar to 316d097c4cd4  (x86/pti: Filter at
> > vma->vm_page_prot population) which give a choice for arch custom
> > implementation.
>
> How?  To me it looks like a bad duplication of such functionality in
> a way that totally breaks abstractions.  architectures really do not
> have any business changing protection_map.
D1's _P/SXXX definintion is different from riscv standard spec to get
non-coherency supported. It sets the highest bits and current spec
must keep zero. So we using a global variable struct in the _P/SXXX
definition to let vendors init their own _P/SXXX values during
bootstrap that is very early stage before setup_vm().


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/