arm64/cpufeature: detect pointer authentication

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.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
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>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index a89f587..803f388 100644 (file)
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -56,7 +56,13 @@
 #define ARM64_WORKAROUND_1188873               35
 #define ARM64_HAS_SB                           36
 #define ARM64_WORKAROUND_1165522               37
+#define ARM64_HAS_ADDRESS_AUTH_ARCH            38
+#define ARM64_HAS_ADDRESS_AUTH_IMP_DEF         39
+#define ARM64_HAS_ADDRESS_AUTH                 40
+#define ARM64_HAS_GENERIC_AUTH_ARCH            41
+#define ARM64_HAS_GENERIC_AUTH_IMP_DEF         42
+#define ARM64_HAS_GENERIC_AUTH                 43
 
-#define ARM64_NCAPS                            38
+#define ARM64_NCAPS                            44
 
 #endif /* __ASM_CPUCAPS_H */

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 38e674f..daec4b5 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -565,6 +565,18 @@ 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 7b6f26f..c82ebd8 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -143,9 +143,17 @@ static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
 
 static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_SB_SHIFT, 4, 0),
+       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,
 };
@@ -1182,6 +1190,36 @@ 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",
@@ -1415,6 +1453,58 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
                .sign = FTR_UNSIGNED,
                .min_field_value = 1,
        },
+#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 */
        {},
 };