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arm64: enable the Permission Overlay Extension for EL0

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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@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20240822151113.1479789-12-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Joey Gouly 2024-08-22 16:10:54 +01:00 committed by Will Deacon
parent 9f82f15ddf
commit bf83dae90f
5 changed files with 19 additions and 0 deletions
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2
Documentation/arch/arm64/elf_hwcaps.rst
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@ -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
-----------------------

1
arch/arm64/include/asm/hwcap.h
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@ -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

1
arch/arm64/include/uapi/asm/hwcap.h
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@ -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 */

14
arch/arm64/kernel/cpufeature.c
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@ -466,6 +466,8 @@ 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,
@ -2348,6 +2350,14 @@ 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)
@ -2876,6 +2886,7 @@ 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
@ -3043,6 +3054,9 @@ 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
{},
};

1
arch/arm64/kernel/cpuinfo.c
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@ -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