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Date: Mon, 30 Jun 2025 11:08:15 +0100
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Subject: Re: [PATCH 3/3] kselftest/arm64: Add lsfe to the hwcaps test
To: Mark Brown <broonie@kernel.org>, Catalin Marinas
 <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>,
 Jonathan Corbet <corbet@lwn.net>, Marc Zyngier <maz@kernel.org>,
 Oliver Upton <oliver.upton@linux.dev>, Joey Gouly <joey.gouly@arm.com>,
 Suzuki K Poulose <suzuki.poulose@arm.com>, Shuah Khan <shuah@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
 linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev,
 linux-kselftest@vger.kernel.org
References: <20250627-arm64-lsfe-v1-0-68351c4bf741@kernel.org>
 <20250627-arm64-lsfe-v1-3-68351c4bf741@kernel.org>
Content-Language: en-US
From: Ben Horgan <ben.horgan@arm.com>
In-Reply-To: <20250627-arm64-lsfe-v1-3-68351c4bf741@kernel.org>
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Hi Mark,

On 6/27/25 18:20, Mark Brown wrote:
> This feature has no traps associated with it so the SIGILL is not reliable.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>   tools/testing/selftests/arm64/abi/hwcap.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
> 
> diff --git a/tools/testing/selftests/arm64/abi/hwcap.c b/tools/testing/selftests/arm64/abi/hwcap.c
> index 35f521e5f41c..9dfca2eb7c41 100644
> --- a/tools/testing/selftests/arm64/abi/hwcap.c
> +++ b/tools/testing/selftests/arm64/abi/hwcap.c
> @@ -17,6 +17,8 @@
>   #include <asm/sigcontext.h>
>   #include <asm/unistd.h>
>   
> +#include <linux/auxvec.h>
> +
>   #include "../../kselftest.h"
>   
>   #define TESTS_PER_HWCAP 3
> @@ -165,6 +167,18 @@ static void lse128_sigill(void)
>   		     : "cc", "memory");
>   }
>   
> +static void lsfe_sigill(void)
> +{
> +	float __attribute__ ((aligned (16))) mem = 0;
> +	register float *memp asm ("x0") = &mem;
> +
> +	/* LDFADD H0, H0, [X0] */
> +	asm volatile(".inst 0x7c600000"
Same effect, but isn't this the release variant, LDFADDL?
> +		     : "+r" (memp)
> +		     :
> +		     : "cc", "memory");
> +}
> +
>   static void lut_sigill(void)
>   {
>   	/* LUTI2 V0.16B, { V0.16B }, V[0] */
> @@ -758,6 +772,13 @@ static const struct hwcap_data {
>   		.cpuinfo = "lse128",
>   		.sigill_fn = lse128_sigill,
>   	},
> +	{
> +		.name = "LSFE",
> +		.at_hwcap = AT_HWCAP3,
> +		.hwcap_bit = HWCAP3_LSFE,
> +		.cpuinfo = "lsfe",
> +		.sigill_fn = lsfe_sigill,
> +	},
>   	{
>   		.name = "LUT",
>   		.at_hwcap = AT_HWCAP2,
> 

Thanks,

Ben