[PATCH] arm64/sme: Fix tests for 0b1111 value ID registers

[PATCH] arm64/sme: Fix tests for 0b1111 value ID registers

[Mark Brown]

For both ID_AA64SMFR0_EL1.I16I64 and ID_AA64SMFR0_EL1.I8I32 we check for
the presence of the feature by looking for a specific ID value of 0x4 but
should instead be checking for the value 0xf defined by the architecture.

This had no practical effect since we are looking for values >= our define
and the only valid values in the architecture are 0b0000 and 0b1111 so we
would detect things appropriately with the architecture as it stands even
with the incorrect defines.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/include/asm/sysreg.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 084bacc16fa3..6d4f5683ba24 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -775,9 +775,9 @@
 #define ID_AA64SMFR0_F32F32_SHIFT	32
 
 #define ID_AA64SMFR0_FA64		0x1
-#define ID_AA64SMFR0_I16I64		0x4
+#define ID_AA64SMFR0_I16I64		0xf
 #define ID_AA64SMFR0_F64F64		0x1
-#define ID_AA64SMFR0_I8I32		0x4
+#define ID_AA64SMFR0_I8I32		0xf
 #define ID_AA64SMFR0_F16F32		0x1
 #define ID_AA64SMFR0_B16F32		0x1
 #define ID_AA64SMFR0_F32F32		0x1
-- 
2.30.2


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Re: [PATCH] arm64/sme: Fix tests for 0b1111 value ID registers

[Catalin Marinas]

On Tue, 7 Jun 2022 17:51:28 +0100, Mark Brown wrote:
> For both ID_AA64SMFR0_EL1.I16I64 and ID_AA64SMFR0_EL1.I8I32 we check for
> the presence of the feature by looking for a specific ID value of 0x4 but
> should instead be checking for the value 0xf defined by the architecture.
> 
> This had no practical effect since we are looking for values >= our define
> and the only valid values in the architecture are 0b0000 and 0b1111 so we
> would detect things appropriately with the architecture as it stands even
> with the incorrect defines.

The risk is that the architects start making use of the intermiediate
values. So better to have this fixed.

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64/sme: Fix tests for 0b1111 value ID registers
      https://git.kernel.org/arm64/c/a3d52ac77500

-- 
Catalin


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