Linux Kernel Selftest development
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From: Mark Brown <broonie@kernel.org>
To: Yifan Wu <wuyifan50@huawei.com>
Cc: catalin.marinas@arm.com, will@kernel.org, shuah@kernel.org,
	yeoreum.yun@arm.com, jonathan.cameron@huawei.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kselftest@vger.kernel.org, linuxarm@huawei.com,
	xiaqinxin@huawei.com, prime.zeng@hisilicon.com,
	wangyushan12@huawei.com, xuwei5@huawei.com, fanghao11@huawei.com,
	wangzhou1@hisilicon.com
Subject: Re: [PATCH 1/2] selftests/arm64: Implement cmpbr_sigill() to hwcap test
Date: Sat, 28 Feb 2026 13:23:31 +0000	[thread overview]
Message-ID: <aaLsU2sBQh3nW9c6@sirena.co.uk> (raw)
In-Reply-To: <20260227031933.4103333-2-wuyifan50@huawei.com>

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On Fri, Feb 27, 2026 at 11:19:32AM +0800, Yifan Wu wrote:

>  static void cmpbr_sigill(void)
>  {
> -	/* Not implemented, too complicated and unreliable anyway */
> +	/* CBEQ x0, x0, +8 */
> +	asm volatile(".inst 0x74C00040" : : : "x0");
> +	/* UDF #0 */
> +	asm volatile("udf #0" : : : );
>  }

I don't expect it to make a difference but it'd be nice if these were a
single asm volatile statement, just to make it absolutely clear that no
instrumentation or anything is supposed to go between the two.

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  reply	other threads:[~2026-02-28 13:23 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-27  3:19 [PATCH 0/2] selftests/arm64: Add cmpbr_sigill() and fix sve2p1_sigill() for hwcap test Yifan Wu
2026-02-27  3:19 ` [PATCH 1/2] selftests/arm64: Implement cmpbr_sigill() to " Yifan Wu
2026-02-28 13:23   ` Mark Brown [this message]
2026-03-02  3:50     ` wuyifan
2026-02-27  3:19 ` [PATCH 2/2] selftest/arm64: Fix sve2p1_sigill() " Yifan Wu
2026-02-28 13:39   ` Mark Brown
2026-03-02  3:40     ` wuyifan

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