Re: [PATCH] riscv: fix KUnit test_kprobes crash when building with Clang

From: Paul Walmsley <pjw@kernel.org>
To: 许佳凯 <xujiakai2025@iscas.ac.cn>, "Nathan Chancellor" <nathan@kernel.org>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	 Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	 Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	 namcao@linutronix.de
Subject: Re: [PATCH] riscv: fix KUnit test_kprobes crash when building with Clang
Date: Sat, 15 Nov 2025 22:15:19 -0700 (MST)	[thread overview]
Message-ID: <621798fc-68bc-504c-755f-0a2f1f83d1c2@kernel.org> (raw)
In-Reply-To: <738dd4e2.ff73.19a7cd7b4d5.Coremail.xujiakai2025@iscas.ac.cn>

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+ Nam Cao, Nathan Chancellor 

On Thu, 13 Nov 2025, 许佳凯 wrote:

> Clang misaligns the test_kprobes_addresses and test_kprobes_functions
> arrays, or does not export local labels by default. Both can cause
> kmalloc_array() allocation errors and KUnit failures.
> 
> This patch fixes the issue by:
> - Adding .section .rodata to explicitly place arrays in the read-only data segment.
> - Adding .align 3 to align arrays to 8 bytes.
> - Adding .globl to probe labels to ensure symbols are visible.
> 
> For detailed debug and analysis, see:
> https://github.com/j1akai/temp/blob/main/20251113/readme.md
> 
> Signed-off-by: Jiakai Xu <xujiakai2025@iscas.ac.cn>

Hello Jiakai Xu,

Thanks for the patch.  Have you reported this difference in behavior to 
the Clang/LLVM folks so they can render an opinion on it?  We can consider 
this as a short term workaround if it's indeed a toolchain issue, but I'd 
like to hear from the LLVM folks.

Also: could you please include the narrative from your page 

    https://github.com/j1akai/temp/blob/main/20251113/readme.md 

in the patch description, just in case that URL eventually becomes 
unavailable?

thanks,

- Paul

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