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Date:   Mon, 24 Jul 2023 15:31:01 +0100
From:   Conor Dooley <conor.dooley@microchip.com>
To:     Alexandre Ghiti <alexghiti@rivosinc.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>
Subject: Re: [PATCH v6 0/5] riscv: Introduce KASLR
Message-ID: <20230724-sanded-dental-c9125c76ad74@wendy>
References: <20230722123850.634544-1-alexghiti@rivosinc.com>
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Hey Alex,

On Sat, Jul 22, 2023 at 02:38:45PM +0200, Alexandre Ghiti wrote:
> The following KASLR implementation allows to randomize the kernel mapping:
>=20
> - virtually: we expect the bootloader to provide a seed in the device-tree
> - physically: only implemented in the EFI stub, it relies on the firmware=
 to
>   provide a seed using EFI_RNG_PROTOCOL. arm64 has a similar implementati=
on
>   hence the patch 3 factorizes KASLR related functions for riscv to take
>   advantage.
>=20
> The new virtual kernel location is limited by the early page table that o=
nly
> has one PUD and with the PMD alignment constraint, the kernel can only ta=
ke
> < 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>

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

Cheers,
Conor.


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