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References: <20230722123850.634544-1-alexghiti@rivosinc.com> <20230724-sanded-dental-c9125c76ad74@wendy>
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From:   Alexandre Ghiti <alexghiti@rivosinc.com>
Date:   Tue, 25 Jul 2023 09:08:01 +0200
Message-ID: <CAHVXubhiYT07L2ve2iEB5AZZdOgA0Sux8vDP4tMfdR6UTWuMgg@mail.gmail.com>
Subject: Re: [PATCH v6 0/5] riscv: Introduce KASLR
To:     Conor Dooley <conor.dooley@microchip.com>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Ard Biesheuvel <ardb@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org
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On Mon, Jul 24, 2023 at 4:32=E2=80=AFPM Conor Dooley <conor.dooley@microchi=
p.com> wrote:
>
> Hey Alex,
>
> On Sat, Jul 22, 2023 at 02:38:45PM +0200, Alexandre Ghiti wrote:
> > The following KASLR implementation allows to randomize the kernel mappi=
ng:
> >
> > - virtually: we expect the bootloader to provide a seed in the device-t=
ree
> > - physically: only implemented in the EFI stub, it relies on the firmwa=
re to
> >   provide a seed using EFI_RNG_PROTOCOL. arm64 has a similar implementa=
tion
> >   hence the patch 3 factorizes KASLR related functions for riscv to tak=
e
> >   advantage.
> >
> > The new virtual kernel location is limited by the early page table that=
 only
> > has one PUD and with the PMD alignment constraint, the kernel can only =
take
> > < 512 positions.
>
> I gave this all a go today, it seems to do what it it says on the tin,
> and crashing my kernel does dump out an offset etc.
>
> Tested-by: Conor Dooley <conor.dooley@microchip.com>

Great, thanks for testing!

>
> I'll hopefully get some time later in the week to go through the code.

I will be on holiday in 3 weeks, you have some time, no worries :)

Thanks again,

Alex

>
> Cheers,
> Conor.
>