linux-kernel - Re: [PATCH v2] riscv: fix KUnit test_kprobes crash when building with Clang

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Message-ID: <5cad53b9-e6f7-d8c8-8c54-c4e5af035bbf@kernel.org>
Date: Tue, 30 Dec 2025 20:15:28 -0700 (MST)
From: Paul Walmsley <pjw@...nel.org>
To: Jiakai Xu <jiakaipeanut@...il.com>
cc: linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, 
    Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, 
    Albert Ou <aou@...s.berkeley.edu>, Nam Cao <namcao@...utronix.de>, 
    Alexandre Ghiti <alex@...ti.fr>, Jiakai Xu <xujiakai2025@...as.ac.cn>
Subject: Re: [PATCH v2] riscv: fix KUnit test_kprobes crash when building
 with Clang

Hi Jiakai Xu,

thanks for updating this patch -

On Fri, 26 Dec 2025, Jiakai Xu wrote:

> Clang misinterprets the placement of test_kprobes_addresses and 
> test_kprobes_functions arrays when they are not explicitly assigned 
> to a data section. This can lead to kmalloc_array() allocation 
> errors and KUnit failures.
> 
> When testing the Clang-compiled code in QEMU, this warning was emitted:
> 
> WARNING: CPU: 1 PID: 3000 at mm/page_alloc.c:5159 __alloc_frozen_pages_noprof+0xe6/0x2fc mm/page_alloc.c:5159
> 
> Further investigation revealed that the test_kprobes_addresses array
> appeared to have over 100,000 elements, including invalid addresses;
> whereas, according to test-kprobes-asm.S, test_kprobes_addresses
> should only have 25 elements.
> 
> When compiling the kernel with GCC, the kernel boots correctly.
> 
> This patch fixes the issue by adding .section .rodata to explicitly 
> place arrays in the read-only data segment.
> 
> For detailed debug and analysis, see:
> https://github.com/j1akai/temp/blob/main/20251113/readme.md
> 
> Signed-off-by: Jiakai Xu <xujiakai2025@...as.ac.cn>
> Signed-off-by: Jiakai Xu <jiakaiPeanut@...il.com>
> Link: https://patch.msgid.link/738dd4e2.ff73.19a7cd7b4d5.Coremail.xujiakai2025@iscas.ac.cn
> Link: https://github.com/llvm/llvm-project/issues/168308
> 
> v1 -> v2：
> - Drop changes to .align, and .globl.

This should go below the --- line (or above the Signed-off-by:, Link: 
lines).  There shouldn't be anything between the Signed-off-by:, Link: 
trailers and the ---.

I've fixed this up locally, and queued for v6.19-rc.

> 
> ---
>  arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
> index b951d0f12482..f16deee9e091 100644
> --- a/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
> +++ b/arch/riscv/kernel/tests/kprobes/test-kprobes-asm.S
> @@ -181,6 +181,7 @@ SYM_FUNC_END(test_kprobes_c_bnez)
>  
>  #endif /* CONFIG_RISCV_ISA_C */
>  
> +.section .rodata
>  SYM_DATA_START(test_kprobes_addresses)
>  	RISCV_PTR test_kprobes_add_addr1
>  	RISCV_PTR test_kprobes_add_addr2
> @@ -212,6 +213,7 @@ SYM_DATA_START(test_kprobes_addresses)
>  	RISCV_PTR 0
>  SYM_DATA_END(test_kprobes_addresses)
>  
> +.section .rodata
>  SYM_DATA_START(test_kprobes_functions)
>  	RISCV_PTR test_kprobes_add
>  	RISCV_PTR test_kprobes_jal
> -- 
> 2.34.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
> 

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