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

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Message-ID: <875xax5eq8.fsf@yellow.woof>
Date: Wed, 26 Nov 2025 10:23:59 +0100
From: Nam Cao <namcao@...utronix.de>
To: 许佳凯 <xujiakai2025@...as.ac.cn>,
 linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Cc: Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>,
 Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>
Subject: Re: [PATCH] riscv: fix KUnit test_kprobes crash when building with
 Clang

许佳凯 <xujiakai2025@...as.ac.cn> writes:
> 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.

We do not have to make it exactly the same as building with GCC, right?
Only moving the arrays to .rodata seems sufficient to fix the issue, but
I cannot explain why yet.

What I observed is that with CONFIG_RELOCATABLE=y, the kernel's
.rela.dyn section, which holds the relocation entries for the two
arrays, have incorrect addresses (they are all incorrectly offset by 6
bytes for my build). The kernel uses these relocation information to
fill the arrays during boot, and fill them at wrong addresses.

I smell a linker problem, but more investigation needed...

Nam