linux-kernel - [PATCH v4 1/7] arm64/cpufeature: add MTE_STORE

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Message-Id: <20250507154654.1937588-2-yeoreum.yun@arm.com>
Date: Wed,  7 May 2025 16:46:48 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: catalin.marinas@....com,
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Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Yeoreum Yun <yeoreum.yun@....com>
Subject: [PATCH v4 1/7] arm64/cpufeature: add MTE_STORE_ONLY feature

Since ARMv8.9, FEAT_MTE_STORE_ONLY can be used to restrict raise of tag
check fault on store operation only.

add MTE_STORE_ONLY feature.

Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
---
 arch/arm64/kernel/cpufeature.c | 8 ++++++++
 arch/arm64/tools/cpucaps       | 1 +
 2 files changed, 9 insertions(+)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 183b4b7e3074..de42f890bcd7 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -313,6 +313,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
 static const struct arm64_ftr_bits ftr_id_aa64pfr2[] = {
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR2_EL1_FPMR_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR2_EL1_MTEFAR_SHIFT, 4, ID_AA64PFR2_EL1_MTEFAR_NI),
+	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR2_EL1_MTESTOREONLY_SHIFT, 4, ID_AA64PFR2_EL1_MTESTOREONLY_NI),
 	ARM64_FTR_END,
 };
 
@@ -2869,6 +2870,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.matches = has_cpuid_feature,
 		ARM64_CPUID_FIELDS(ID_AA64PFR2_EL1, MTEFAR, IMP)
 	},
+	{
+		.desc = "Store Only MTE Tag Check",
+		.capability = ARM64_MTE_STORE_ONLY,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		ARM64_CPUID_FIELDS(ID_AA64PFR2_EL1, MTESTOREONLY, IMP)
+	},
 #endif /* CONFIG_ARM64_MTE */
 	{
 		.desc = "RCpc load-acquire (LDAPR)",
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index ef62ea04ba37..282a1dbb8bc9 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -68,6 +68,7 @@ MPAM_HCR
 MTE
 MTE_ASYMM
 MTE_FAR
+MTE_STORE_ONLY
 SME
 SME_FA64
 SME2
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}