[PATCH v4 02/17] arm64: cpufeature: add pointer auth meta-capabilities

From: Amit Daniel Kachhap <amit.kachhap@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Kristina Martsenko <kristina.martsenko@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Mark Brown <broonie@kernel.org>,
	James Morse <james.morse@arm.com>,
	Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
	Amit Daniel Kachhap <amit.kachhap@arm.com>,
	Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
	Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH v4 02/17] arm64: cpufeature: add pointer auth meta-capabilities
Date: Thu, 23 Jan 2020 15:50:24 +0530	[thread overview]
Message-ID: <1579774839-19562-3-git-send-email-amit.kachhap@arm.com> (raw)
In-Reply-To: <1579774839-19562-1-git-send-email-amit.kachhap@arm.com>

From: Kristina Martsenko <kristina.martsenko@arm.com>

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>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit message and macro rebase, use system_has_cap]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since v3:
 * uses the new helper system_has_cap added earlier.

 arch/arm64/include/asm/cpucaps.h    |  4 +++-
 arch/arm64/include/asm/cpufeature.h |  6 ++----
 arch/arm64/kernel/cpufeature.c      | 25 ++++++++++++++++++++++++-
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index b926838..6674ad1 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -56,7 +56,9 @@
 #define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
 #define ARM64_WORKAROUND_1542419		47
 #define ARM64_WORKAROUND_1319367		48
+#define ARM64_HAS_ADDRESS_AUTH			49
+#define ARM64_HAS_GENERIC_AUTH			50
 
-#define ARM64_NCAPS				49
+#define ARM64_NCAPS				51
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 695e538..8579427 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -591,15 +591,13 @@ 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 74d6c13..378329d6 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1249,6 +1249,20 @@ 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_has_cap(ARM64_HAS_ADDRESS_AUTH_ARCH) ||
+	       system_has_cap(ARM64_HAS_ADDRESS_AUTH_IMP_DEF);
+}
+
+static bool has_generic_auth(const struct arm64_cpu_capabilities *entry,
+			     int __unused)
+{
+	return system_has_cap(ARM64_HAS_GENERIC_AUTH_ARCH) ||
+	       system_has_cap(ARM64_HAS_GENERIC_AUTH_IMP_DEF);
+}
 #endif /* CONFIG_ARM64_PTR_AUTH */
 
 #ifdef CONFIG_ARM64_PSEUDO_NMI
@@ -1518,7 +1532,6 @@ 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)",
@@ -1529,6 +1542,11 @@ 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,
 	},
 	{
@@ -1551,6 +1569,11 @@ 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
 	{
-- 
2.7.4


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