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Subject[PATCH v6 06/13] arm64/cpufeature: detect pointer authentication
Date
From: Mark Rutland <mark.rutland@arm.com>

So that we can dynamically handle the presence of pointer authentication
functionality, wire up probing code in cpufeature.c.

From ARMv8.3 onwards, ID_AA64ISAR1 is no longer entirely RES0, and now
has four fields describing the presence of pointer authentication
functionality:

* APA - address authentication present, using an architected algorithm
* API - address authentication present, using an IMP DEF algorithm
* GPA - generic authentication present, using an architected algorithm
* GPI - generic authentication present, using an IMP DEF algorithm

This patch checks for both address and generic authentication,
separately. It is assumed that if all CPUs support an IMP DEF algorithm,
the same algorithm is used across all CPUs.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/cpucaps.h | 8 +++-
arch/arm64/include/asm/cpufeature.h | 12 +++++
arch/arm64/kernel/cpufeature.c | 90 +++++++++++++++++++++++++++++++++++++
3 files changed, 109 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 6e2d254c09eb..62fc48604263 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -54,7 +54,13 @@
#define ARM64_HAS_CRC32 33
#define ARM64_SSBS 34
#define ARM64_WORKAROUND_1188873 35
+#define ARM64_HAS_ADDRESS_AUTH_ARCH 36
+#define ARM64_HAS_ADDRESS_AUTH_IMP_DEF 37
+#define ARM64_HAS_ADDRESS_AUTH 38
+#define ARM64_HAS_GENERIC_AUTH_ARCH 39
+#define ARM64_HAS_GENERIC_AUTH_IMP_DEF 40
+#define ARM64_HAS_GENERIC_AUTH 41

-#define ARM64_NCAPS 36
+#define ARM64_NCAPS 42

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 7e2ec64aa414..1c8393ffabff 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -514,6 +514,18 @@ static inline bool system_supports_cnp(void)
cpus_have_const_cap(ARM64_HAS_CNP);
}

+static inline bool system_supports_address_auth(void)
+{
+ return IS_ENABLED(CONFIG_ARM64_PTR_AUTH) &&
+ cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH);
+}
+
+static inline bool system_supports_generic_auth(void)
+{
+ return IS_ENABLED(CONFIG_ARM64_PTR_AUTH) &&
+ cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH);
+}
+
#define ARM64_SSBD_UNKNOWN -1
#define ARM64_SSBD_FORCE_DISABLE 0
#define ARM64_SSBD_KERNEL 1
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index aec5ecb85737..f8e3c3568a79 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -141,9 +141,17 @@ static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
};

static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
+ FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_GPI_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
+ FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_GPA_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_LRCPC_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_FCMA_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_JSCVT_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
+ FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_API_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
+ FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_APA_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_DPB_SHIFT, 4, 0),
ARM64_FTR_END,
};
@@ -1145,6 +1153,36 @@ static void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused)
}
#endif /* CONFIG_ARM64_RAS_EXTN */

+#ifdef CONFIG_ARM64_PTR_AUTH
+static bool has_address_auth(const struct arm64_cpu_capabilities *entry,
+ int __unused)
+{
+ u64 isar1 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR1_EL1);
+ bool api, apa;
+
+ apa = cpuid_feature_extract_unsigned_field(isar1,
+ ID_AA64ISAR1_APA_SHIFT) > 0;
+ api = cpuid_feature_extract_unsigned_field(isar1,
+ ID_AA64ISAR1_API_SHIFT) > 0;
+
+ return apa || api;
+}
+
+static bool has_generic_auth(const struct arm64_cpu_capabilities *entry,
+ int __unused)
+{
+ u64 isar1 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR1_EL1);
+ bool gpi, gpa;
+
+ gpa = cpuid_feature_extract_unsigned_field(isar1,
+ ID_AA64ISAR1_GPA_SHIFT) > 0;
+ gpi = cpuid_feature_extract_unsigned_field(isar1,
+ ID_AA64ISAR1_GPI_SHIFT) > 0;
+
+ return gpa || gpi;
+}
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "GIC system register CPU interface",
@@ -1368,6 +1406,58 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.cpu_enable = cpu_enable_cnp,
},
#endif
+#ifdef CONFIG_ARM64_PTR_AUTH
+ {
+ .desc = "Address authentication (architected algorithm)",
+ .capability = ARM64_HAS_ADDRESS_AUTH_ARCH,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .sys_reg = SYS_ID_AA64ISAR1_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64ISAR1_APA_SHIFT,
+ .min_field_value = ID_AA64ISAR1_APA_ARCHITECTED,
+ .matches = has_cpuid_feature,
+ },
+ {
+ .desc = "Address authentication (IMP DEF algorithm)",
+ .capability = ARM64_HAS_ADDRESS_AUTH_IMP_DEF,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .sys_reg = SYS_ID_AA64ISAR1_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64ISAR1_API_SHIFT,
+ .min_field_value = ID_AA64ISAR1_API_IMP_DEF,
+ .matches = has_cpuid_feature,
+ },
+ {
+ .capability = ARM64_HAS_ADDRESS_AUTH,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_address_auth,
+ },
+ {
+ .desc = "Generic authentication (architected algorithm)",
+ .capability = ARM64_HAS_GENERIC_AUTH_ARCH,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .sys_reg = SYS_ID_AA64ISAR1_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64ISAR1_GPA_SHIFT,
+ .min_field_value = ID_AA64ISAR1_GPA_ARCHITECTED,
+ .matches = has_cpuid_feature,
+ },
+ {
+ .desc = "Generic authentication (IMP DEF algorithm)",
+ .capability = ARM64_HAS_GENERIC_AUTH_IMP_DEF,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .sys_reg = SYS_ID_AA64ISAR1_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64ISAR1_GPI_SHIFT,
+ .min_field_value = ID_AA64ISAR1_GPI_IMP_DEF,
+ .matches = has_cpuid_feature,
+ },
+ {
+ .capability = ARM64_HAS_GENERIC_AUTH,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_generic_auth,
+ },
+#endif /* CONFIG_ARM64_PTR_AUTH */
{},
};

--
2.11.0
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