[PATCH] arm64/sme: Add hwcap for Scalable Matrix Extension
From: Tianjia Zhang
Date: Thu Apr 14 2022 - 07:55:53 EST
Allow userspace to detect support for SME (Scalable Matrix Extension)
by providing a hwcap for it, using the official feature name FEAT_SME,
declared in ARM DDI 0487H.a specification.
Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
---
Documentation/arm64/elf_hwcaps.rst | 4 ++++
arch/arm64/include/asm/hwcap.h | 1 +
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/include/uapi/asm/hwcap.h | 1 +
arch/arm64/kernel/cpufeature.c | 13 +++++++++++++
arch/arm64/kernel/cpuinfo.c | 1 +
arch/arm64/tools/cpucaps | 1 +
7 files changed, 22 insertions(+)
diff --git a/Documentation/arm64/elf_hwcaps.rst b/Documentation/arm64/elf_hwcaps.rst
index a8f30963e550..50d2309a60d5 100644
--- a/Documentation/arm64/elf_hwcaps.rst
+++ b/Documentation/arm64/elf_hwcaps.rst
@@ -264,6 +264,10 @@ HWCAP2_MTE3
Functionality implied by ID_AA64PFR1_EL1.MTE == 0b0011, as described
by Documentation/arm64/memory-tagging-extension.rst.
+HWCAP2_SME
+
+ Functionality implied by ID_AA64PFR1_EL1.SME == 0b0001.
+
4. Unused AT_HWCAP bits
-----------------------
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 8db5ec0089db..5299afc30fb0 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -109,6 +109,7 @@
#define KERNEL_HWCAP_AFP __khwcap2_feature(AFP)
#define KERNEL_HWCAP_RPRES __khwcap2_feature(RPRES)
#define KERNEL_HWCAP_MTE3 __khwcap2_feature(MTE3)
+#define KERNEL_HWCAP_SME __khwcap2_feature(SME)
/*
* This yields a mask that user programs can use to figure out what
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index fbf5f8bb9055..e66f9360cd93 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -836,6 +836,7 @@
#define ID_AA64PFR0_ELx_32BIT_64BIT 0x2
/* id_aa64pfr1 */
+#define ID_AA64PFR1_SME_SHIFT 24
#define ID_AA64PFR1_MPAMFRAC_SHIFT 16
#define ID_AA64PFR1_RASFRAC_SHIFT 12
#define ID_AA64PFR1_MTE_SHIFT 8
diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index 99cb5d383048..0371779c7ca2 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -79,5 +79,6 @@
#define HWCAP2_AFP (1 << 20)
#define HWCAP2_RPRES (1 << 21)
#define HWCAP2_MTE3 (1 << 22)
+#define HWCAP2_SME (1 << 23)
#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index d72c4b4d389c..55c5e4b9c50e 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -261,6 +261,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
};
static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
+ ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SME_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_MPAMFRAC_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_RASFRAC_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_MTE),
@@ -2442,6 +2443,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = has_cpuid_feature,
.min_field_value = 1,
},
+ {
+ .desc = "Scalable Matrix Extension",
+ .capability = ARM64_SME,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_cpuid_feature,
+ .sys_reg = SYS_ID_AA64PFR1_EL1,
+ .field_pos = ID_AA64PFR1_SME_SHIFT,
+ .field_width = 4,
+ .sign = FTR_UNSIGNED,
+ .min_field_value = 1,
+ },
{},
};
@@ -2572,6 +2584,7 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_MTE_SHIFT, 4, FTR_UNSIGNED, ID_AA64PFR1_MTE, CAP_HWCAP, KERNEL_HWCAP_MTE),
HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_MTE_SHIFT, 4, FTR_UNSIGNED, ID_AA64PFR1_MTE_ASYMM, CAP_HWCAP, KERNEL_HWCAP_MTE3),
#endif /* CONFIG_ARM64_MTE */
+ HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_SME_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SME),
HWCAP_CAP(SYS_ID_AA64MMFR0_EL1, ID_AA64MMFR0_ECV_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ECV),
HWCAP_CAP(SYS_ID_AA64MMFR1_EL1, ID_AA64MMFR1_AFP_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_AFP),
HWCAP_CAP(SYS_ID_AA64ISAR2_EL1, ID_AA64ISAR2_RPRES_SHIFT, 4, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_RPRES),
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 330b92ea863a..87be4ba601eb 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -98,6 +98,7 @@ static const char *const hwcap_str[] = {
[KERNEL_HWCAP_AFP] = "afp",
[KERNEL_HWCAP_RPRES] = "rpres",
[KERNEL_HWCAP_MTE3] = "mte3",
+ [KERNEL_HWCAP_SME] = "sme",
};
#ifdef CONFIG_COMPAT
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 3ed418f70e3b..c0c05399b24a 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -49,6 +49,7 @@ SPECTRE_V4
SPECTRE_BHB
SSBS
SVE
+SME
UNMAP_KERNEL_AT_EL0
WORKAROUND_834220
WORKAROUND_843419
--
2.24.3 (Apple Git-128)