Expose a HWCAP and ID_AA64MMFR3_EL1_S1POE to userspace, so they can be used to
check if the CPU supports the feature.
Signed-off-by: Joey Gouly <joey.gouly@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
---
This takes the last bit of HWCAP2, is this fine? What can we do about more features in the future?
Documentation/arch/arm64/elf_hwcaps.rst | 2 ++
arch/arm64/include/asm/hwcap.h | 1 +
arch/arm64/include/uapi/asm/hwcap.h | 1 +
arch/arm64/kernel/cpufeature.c | 14 ++++++++++++++
arch/arm64/kernel/cpuinfo.c | 1 +
5 files changed, 19 insertions(+)
diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
index 448c1664879b..694f67fa07d1 100644
--- a/Documentation/arch/arm64/elf_hwcaps.rst
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -365,6 +365,8 @@ HWCAP2_SME_SF8DP2
HWCAP2_SME_SF8DP4
Functionality implied by ID_AA64SMFR0_EL1.SF8DP4 == 0b1.
+HWCAP2_POE
+ Functionality implied by ID_AA64MMFR3_EL1.S1POE == 0b0001.
4. Unused AT_HWCAP bits
-----------------------
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 4edd3b61df11..a775adddecf2 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -157,6 +157,7 @@
#define KERNEL_HWCAP_SME_SF8FMA __khwcap2_feature(SME_SF8FMA)
#define KERNEL_HWCAP_SME_SF8DP4 __khwcap2_feature(SME_SF8DP4)
#define KERNEL_HWCAP_SME_SF8DP2 __khwcap2_feature(SME_SF8DP2)
+#define KERNEL_HWCAP_POE __khwcap2_feature(POE)
/*
* This yields a mask that user programs can use to figure out what
diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index 285610e626f5..055381b2c615 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -122,5 +122,6 @@
#define HWCAP2_SME_SF8FMA (1UL << 60)
#define HWCAP2_SME_SF8DP4 (1UL << 61)
#define HWCAP2_SME_SF8DP2 (1UL << 62)
+#define HWCAP2_POE (1UL << 63)
#endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 2f3c2346e156..8c02aae9db11 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -465,6 +465,8 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
};
static const struct arm64_ftr_bits ftr_id_aa64mmfr3[] = {
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_POE),
+ FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR3_EL1_S1POE_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR3_EL1_S1PIE_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR3_EL1_TCRX_SHIFT, 4, 0),
ARM64_FTR_END,
@@ -2339,6 +2341,14 @@ static void cpu_enable_mops(const struct arm64_cpu_capabilities *__unused)
sysreg_clear_set(sctlr_el1, 0, SCTLR_EL1_MSCEn);
}
+#ifdef CONFIG_ARM64_POE
+static void cpu_enable_poe(const struct arm64_cpu_capabilities *__unused)
+{
+ sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1x_E0POE);
+ sysreg_clear_set(CPACR_EL1, 0, CPACR_ELx_E0POE);
+}
+#endif
+
/* Internal helper functions to match cpu capability type */
static bool
cpucap_late_cpu_optional(const struct arm64_cpu_capabilities *cap)
@@ -2867,6 +2877,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.capability = ARM64_HAS_S1POE,
.type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
.matches = has_cpuid_feature,
+ .cpu_enable = cpu_enable_poe,
ARM64_CPUID_FIELDS(ID_AA64MMFR3_EL1, S1POE, IMP)
},
#endif
@@ -3034,6 +3045,9 @@ 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, F8E4M3, IMP, CAP_HWCAP, KERNEL_HWCAP_F8E4M3),
HWCAP_CAP(ID_AA64FPFR0_EL1, F8E5M2, IMP, CAP_HWCAP, KERNEL_HWCAP_F8E5M2),
+#ifdef CONFIG_ARM64_POE
+ HWCAP_CAP(ID_AA64MMFR3_EL1, S1POE, IMP, CAP_HWCAP, KERNEL_HWCAP_POE),
+#endif
{},
};
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 09eeaa24d456..b9db812082b3 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -143,6 +143,7 @@ static const char *const hwcap_str[] = {
[KERNEL_HWCAP_SME_SF8FMA] = "smesf8fma",
[KERNEL_HWCAP_SME_SF8DP4] = "smesf8dp4",
[KERNEL_HWCAP_SME_SF8DP2] = "smesf8dp2",
+ [KERNEL_HWCAP_POE] = "poe",
};
#ifdef CONFIG_COMPAT
--
2.25.1
