arm64: cpufeature: add pointer auth meta-capabilities

To enable pointer auth for the kernel, we're going to need to check for
the presence of address auth and generic auth using alternative_if. We
currently have two cpucaps for each, but alternative_if needs to check a
single cpucap. So define meta-capabilities that are present when either
of the current two capabilities is present.

Leave the existing four cpucaps in place, as they are still needed to
check for mismatched systems where one CPU has the architected algorithm
but another has the IMP DEF algorithm.

Note, the meta-capabilities were present before but were removed in
commit a56005d32105 ("arm64: cpufeature: Reduce number of pointer auth
CPU caps from 6 to 4") and commit 1e013d06120c ("arm64: cpufeature: Rework
ptr auth hwcaps using multi_entry_cap_matches"), as they were not needed
then. Note, unlike before, the current patch checks the cpucap values
directly, instead of reading the CPU ID register value.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit message and macro rebase, use __system_matches_cap]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 865e0253fc1ef3c12e496ef8724aececd7677632..72e4e0580ddbdb1d3a98528ced45b6984a879b9f 100644 (file)
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -58,7 +58,9 @@
 #define ARM64_WORKAROUND_SPECULATIVE_AT_NVHE   48
 #define ARM64_HAS_E0PD                         49
 #define ARM64_HAS_RNG                          50
+#define ARM64_HAS_ADDRESS_AUTH                 51
+#define ARM64_HAS_GENERIC_AUTH                 52
 
-#define ARM64_NCAPS                            51
+#define ARM64_NCAPS                            53
 
 #endif /* __ASM_CPUCAPS_H */

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 92ef9539874a663b3bd693c4e834a5cf134a21d6..8c8048372c8e551b9adf4cd7b6dd58f70bb477bd 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -590,15 +590,13 @@ static inline bool system_supports_cnp(void)
 static inline bool system_supports_address_auth(void)
 {
        return IS_ENABLED(CONFIG_ARM64_PTR_AUTH) &&
-               (cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH_ARCH) ||
-                cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH_IMP_DEF));
+               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_ARCH) ||
-                cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH_IMP_DEF));
+               cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH);
 }
 
 static inline bool system_uses_irq_prio_masking(void)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4f2e95e6ecd182ff83f91fe863635cb98ae4e3e4..01f50f0438317a887f8a311b582f9486c7a611c3 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1323,6 +1323,20 @@ static void cpu_enable_address_auth(struct arm64_cpu_capabilities const *cap)
        sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
                                       SCTLR_ELx_ENDA | SCTLR_ELx_ENDB);
 }
+
+static bool has_address_auth(const struct arm64_cpu_capabilities *entry,
+                            int __unused)
+{
+       return __system_matches_cap(ARM64_HAS_ADDRESS_AUTH_ARCH) ||
+              __system_matches_cap(ARM64_HAS_ADDRESS_AUTH_IMP_DEF);
+}
+
+static bool has_generic_auth(const struct arm64_cpu_capabilities *entry,
+                            int __unused)
+{
+       return __system_matches_cap(ARM64_HAS_GENERIC_AUTH_ARCH) ||
+              __system_matches_cap(ARM64_HAS_GENERIC_AUTH_IMP_DEF);
+}
 #endif /* CONFIG_ARM64_PTR_AUTH */
 
 #ifdef CONFIG_ARM64_E0PD
@@ -1600,7 +1614,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
                .field_pos = ID_AA64ISAR1_APA_SHIFT,
                .min_field_value = ID_AA64ISAR1_APA_ARCHITECTED,
                .matches = has_cpuid_feature,
-               .cpu_enable = cpu_enable_address_auth,
        },
        {
                .desc = "Address authentication (IMP DEF algorithm)",
@@ -1611,6 +1624,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
                .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,
                .cpu_enable = cpu_enable_address_auth,
        },
        {
@@ -1633,6 +1651,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
                .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 */
 #ifdef CONFIG_ARM64_PSEUDO_NMI
        {