[PATCH 7/8] arm64/cpufeature: Define hwcaps for 2025 dpISA features

Mark Brown
2026-03-02T22:59:49Z

The features added by the 2025 dpISA are all straightforward instruction
only features so there is no state to manage, we can just expose hwcaps to
let userspace know they are available.

F16MM is slightly odd in that the feature is FEAT_F16MM but it is discovered
via ID_AA64FPFR0_EL1.F16MM2. We follow the feature name.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
Documentation/arch/arm64/elf_hwcaps.rst | 24 ++++++++++++++++++++++++
arch/arm64/include/uapi/asm/hwcap.h | 8 ++++++++
arch/arm64/kernel/cpufeature.c | 11 +++++++++++
arch/arm64/kernel/cpuinfo.c | 8 ++++++++
4 files changed, 51 insertions(+)

diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
index 97315ae6c0da..ea9215d65481 100644
--- a/Documentation/arch/arm64/elf_hwcaps.rst
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -451,6 +451,30 @@ HWCAP3_LS64
of CPU. User should only use ld64b/st64b on supported target (device)
memory location, otherwise fallback to the non-atomic alternatives.

+HWCAP3_SVE_B16MM
+ Functionality implied by ID_AA64ZFR0_EL1.B16B16 == 0b0011
+
+HWCAP3_SVE2P3
+ Functionality implied by ID_AA64ZFR0_EL1.SVEver == 0b0100
+
+HWCAP3_SME_LUT6
+ Functionality implied by ID_AA64SMFR0_EL1.LUT6 == 0b1
+
+HWCAP3_SME2P3
+ Functionality implied by ID_AA64SMFR0_EL1.SMEver == 0b0100
+
+HWCAP3_F16MM
+ Functionality implied by ID_AA64FPFR0_EL1.F16MM2 == 0b1
+
+HWCAP3_F16F32DOT
+ Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0010
+
+HWCAP3_F16F32MM
+ Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0011
+
+HWCAP3_LUT6
+ Functionality implied by ID_AA64ISAR2_EL1.LUT == 0b0010
+

4. Unused AT_HWCAP bits
-----------------------
diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index 06f83ca8de56..a48aee07a54a 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -147,5 +147,13 @@
#define HWCAP3_MTE_STORE_ONLY (1UL << 1)
#define HWCAP3_LSFE (1UL << 2)
#define HWCAP3_LS64 (1UL << 3)
+#define HWCAP3_SVE_B16MM (1UL << 4)
+#define HWCAP3_SVE2P3 (1UL << 5)
+#define HWCAP3_SME_LUT6 (1UL << 6)
+#define HWCAP3_SME2P3 (1UL << 7)
+#define HWCAP3_F16MM (1UL << 8)
+#define HWCAP3_F16F32DOT (1UL << 9)
+#define HWCAP3_F16F32MM (1UL << 10)
+#define HWCAP3_LUT6 (1UL << 11)

#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c31f8e17732a..a26cef210b08 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -361,6 +361,8 @@ static const struct arm64_ftr_bits ftr_id_aa64zfr0[] = {
static const struct arm64_ftr_bits ftr_id_aa64smfr0[] = {
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SME),
FTR_STRICT, FTR_EXACT, ID_AA64SMFR0_EL1_FA64_SHIFT, 1, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SME),
+ FTR_STRICT, FTR_EXACT, ID_AA64SMFR0_EL1_LUT6_SHIFT, 1, 0),
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SME),
FTR_STRICT, FTR_EXACT, ID_AA64SMFR0_EL1_LUTv2_SHIFT, 1, 0),
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SME),
@@ -415,6 +417,7 @@ static const struct arm64_ftr_bits ftr_id_aa64fpfr0[] = {
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, ID_AA64FPFR0_EL1_F8DP2_SHIFT, 1, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, ID_AA64FPFR0_EL1_F8MM8_SHIFT, 1, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, ID_AA64FPFR0_EL1_F8MM4_SHIFT, 1, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, ID_AA64FPFR0_EL1_F16MM2_SHIFT, 1, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, ID_AA64FPFR0_EL1_F8E4M3_SHIFT, 1, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, ID_AA64FPFR0_EL1_F8E5M2_SHIFT, 1, 0),
ARM64_FTR_END,
@@ -3265,6 +3268,8 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(ID_AA64ISAR0_EL1, SM4, IMP, CAP_HWCAP, KERNEL_HWCAP_SM4),
HWCAP_CAP(ID_AA64ISAR0_EL1, DP, IMP, CAP_HWCAP, KERNEL_HWCAP_ASIMDDP),
HWCAP_CAP(ID_AA64ISAR0_EL1, FHM, IMP, CAP_HWCAP, KERNEL_HWCAP_ASIMDFHM),
+ HWCAP_CAP(ID_AA64ISAR0_EL1, FHM, F16F32DOT, CAP_HWCAP, KERNEL_HWCAP_F16F32DOT),
+ HWCAP_CAP(ID_AA64ISAR0_EL1, FHM, F16F32MM, CAP_HWCAP, KERNEL_HWCAP_F16F32MM),
HWCAP_CAP(ID_AA64ISAR0_EL1, TS, FLAGM, CAP_HWCAP, KERNEL_HWCAP_FLAGM),
HWCAP_CAP(ID_AA64ISAR0_EL1, TS, FLAGM2, CAP_HWCAP, KERNEL_HWCAP_FLAGM2),
HWCAP_CAP(ID_AA64ISAR0_EL1, RNDR, IMP, CAP_HWCAP, KERNEL_HWCAP_RNG),
@@ -3290,11 +3295,13 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(ID_AA64ISAR1_EL1, I8MM, IMP, CAP_HWCAP, KERNEL_HWCAP_I8MM),
HWCAP_CAP(ID_AA64ISAR1_EL1, LS64, LS64, CAP_HWCAP, KERNEL_HWCAP_LS64),
HWCAP_CAP(ID_AA64ISAR2_EL1, LUT, IMP, CAP_HWCAP, KERNEL_HWCAP_LUT),
+ HWCAP_CAP(ID_AA64ISAR2_EL1, LUT, LUT6, CAP_HWCAP, KERNEL_HWCAP_LUT6),
HWCAP_CAP(ID_AA64ISAR3_EL1, FAMINMAX, IMP, CAP_HWCAP, KERNEL_HWCAP_FAMINMAX),
HWCAP_CAP(ID_AA64ISAR3_EL1, LSFE, IMP, CAP_HWCAP, KERNEL_HWCAP_LSFE),
HWCAP_CAP(ID_AA64MMFR2_EL1, AT, IMP, CAP_HWCAP, KERNEL_HWCAP_USCAT),
#ifdef CONFIG_ARM64_SVE
HWCAP_CAP(ID_AA64PFR0_EL1, SVE, IMP, CAP_HWCAP, KERNEL_HWCAP_SVE),
+ HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, SVEver, SVE2p3, CAP_HWCAP, KERNEL_HWCAP_SVE2P3),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, SVEver, SVE2p2, CAP_HWCAP, KERNEL_HWCAP_SVE2P2),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, SVEver, SVE2p1, CAP_HWCAP, KERNEL_HWCAP_SVE2P1),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, SVEver, SVE2, CAP_HWCAP, KERNEL_HWCAP_SVE2),
@@ -3304,6 +3311,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, BitPerm, IMP, CAP_HWCAP, KERNEL_HWCAP_SVEBITPERM),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, B16B16, IMP, CAP_HWCAP, KERNEL_HWCAP_SVE_B16B16),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, B16B16, BFSCALE, CAP_HWCAP, KERNEL_HWCAP_SVE_BFSCALE),
+ HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, B16B16, B16MM, CAP_HWCAP, KERNEL_HWCAP_SVE_B16MM),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, BF16, IMP, CAP_HWCAP, KERNEL_HWCAP_SVEBF16),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, BF16, EBF16, CAP_HWCAP, KERNEL_HWCAP_SVE_EBF16),
HWCAP_CAP_MATCH_ID(has_sve_feature, ID_AA64ZFR0_EL1, SHA3, IMP, CAP_HWCAP, KERNEL_HWCAP_SVESHA3),
@@ -3343,7 +3351,9 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
#ifdef CONFIG_ARM64_SME
HWCAP_CAP(ID_AA64PFR1_EL1, SME, IMP, CAP_HWCAP, KERNEL_HWCAP_SME),
HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, FA64, IMP, CAP_HWCAP, KERNEL_HWCAP_SME_FA64),
+ HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, LUT6, IMP, CAP_HWCAP, KERNEL_HWCAP_SME_LUT6),
HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, LUTv2, IMP, CAP_HWCAP, KERNEL_HWCAP_SME_LUTV2),
+ HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, SMEver, SME2p3, CAP_HWCAP, KERNEL_HWCAP_SME2P3),
HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, SMEver, SME2p2, CAP_HWCAP, KERNEL_HWCAP_SME2P2),
HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, SMEver, SME2p1, CAP_HWCAP, KERNEL_HWCAP_SME2P1),
HWCAP_CAP_MATCH_ID(has_sme_feature, ID_AA64SMFR0_EL1, SMEver, SME2, CAP_HWCAP, KERNEL_HWCAP_SME2),
@@ -3374,6 +3384,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(ID_AA64FPFR0_EL1, F8DP2, IMP, CAP_HWCAP, KERNEL_HWCAP_F8DP2),
HWCAP_CAP(ID_AA64FPFR0_EL1, F8MM8, IMP, CAP_HWCAP, KERNEL_HWCAP_F8MM8),
HWCAP_CAP(ID_AA64FPFR0_EL1, F8MM4, IMP, CAP_HWCAP, KERNEL_HWCAP_F8MM4),
+ HWCAP_CAP(ID_AA64FPFR0_EL1, F16MM2, IMP, CAP_HWCAP, KERNEL_HWCAP_F16MM),
HWCAP_CAP(ID_AA64FPFR0_EL1, F8E4M3, IMP, CAP_HWCAP, KERNEL_HWCAP_F8E4M3),
HWCAP_CAP(ID_AA64FPFR0_EL1, F8E5M2, IMP, CAP_HWCAP, KERNEL_HWCAP_F8E5M2),
#ifdef CONFIG_ARM64_POE
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 6149bc91251d..1967ef4e25c8 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -164,6 +164,14 @@ static const char *const hwcap_str[] = {
[KERNEL_HWCAP_MTE_FAR] = "mtefar",
[KERNEL_HWCAP_MTE_STORE_ONLY] = "mtestoreonly",
[KERNEL_HWCAP_LSFE] = "lsfe",
+ [KERNEL_HWCAP_SVE_B16MM] = "sveb16mm",
+ [KERNEL_HWCAP_SVE2P3] = "sve2p3",
+ [KERNEL_HWCAP_SME_LUT6] = "smelut6",
+ [KERNEL_HWCAP_SME2P3] = "sme2p3",
+ [KERNEL_HWCAP_F16MM] = "f16mm",
+ [KERNEL_HWCAP_F16F32DOT] = "f16f32dot",
+ [KERNEL_HWCAP_F16F32MM] = "f16f32mm",
+ [KERNEL_HWCAP_LUT6] = "lut6",
};

#ifdef CONFIG_COMPAT

--
2.47.3