Re: [PATCH v4 0/1] riscv: Allow to downgrade paging mode from the command line

From: Conor Dooley <conor@kernel.org>
To: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v4 0/1] riscv: Allow to downgrade paging mode from the command line
Date: Tue, 31 Jan 2023 19:24:55 +0000	[thread overview]
Message-ID: <Y9lrB+RUBk1Njhaq@spud> (raw)
In-Reply-To: <20230131151115.1972740-1-alexghiti@rivosinc.com>

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Hey Alex,

On Tue, Jan 31, 2023 at 04:11:14PM +0100, Alexandre Ghiti wrote:
> This new version gets rid of the limitation that prevented KASAN kernels
> to use the newly introduced parameters.

What's the base commit for this version?
Fails to apply for me on top of for-next, fixes, rc1, and linux-next :/
I also tried it on top of your KASAN series, but no luck there either!

Thanks,
Conor.

> While looking into KASLR, I fell onto commit aacd149b6238 ("arm64: head:
> avoid relocating the kernel twice for KASLR"): it allows to use the fdt
> functions very early in the boot process with KASAN enabled by simply
> compiling a new version of those functions without instrumentation.
> 
> I had to change the handling of the command line parsing to make the
> code self-contained in kernel/pi/cmd_early.c to avoid calling too many
> __pi prefixed functions from outside this file.
> 
> I'll use this approach like arm64 to handle the extraction of the random
> seedi from the device tree for KASLR.
> 
> @Ard: I copied the "pi" name but I have to admit I don't know what it
> means.
> 
> Alexandre Ghiti (1):
>   riscv: Allow to downgrade paging mode from the command line
> 
>  .../admin-guide/kernel-parameters.txt         |  5 +-
>  arch/riscv/kernel/Makefile                    |  2 +
>  arch/riscv/kernel/pi/Makefile                 | 34 ++++++++++++
>  arch/riscv/kernel/pi/cmdline_early.c          | 52 +++++++++++++++++++
>  arch/riscv/lib/memcpy.S                       |  2 +
>  arch/riscv/lib/memmove.S                      |  2 +
>  arch/riscv/mm/init.c                          | 36 ++++++++++---
>  7 files changed, 126 insertions(+), 7 deletions(-)
>  create mode 100644 arch/riscv/kernel/pi/Makefile
>  create mode 100644 arch/riscv/kernel/pi/cmdline_early.c
> 
> -- 
> 2.37.2
> 

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