[PATCH 0/6] arm64: add support for generic cpu vulnerabilities

[PATCH 0/6] arm64: add support for generic cpu vulnerabilities

[Mian Yousaf Kaukab]

GENERIC_CPU_VULNERABILITIES provide a common way to figure out if a
system is affected by vulnerabilities like meltdown and other variants
of spectre. This small series adds support for it in arm64.

Thank you,

Best regards,
Yousaf

Mian Yousaf Kaukab (6):
  arm64: kpti: move check for non-vulnerable CPUs to a function
  arm64: add sysfs vulnerability show for meltdown
  arm64: add sysfs vulnerability show for spectre v1
  arm64: add sysfs vulnerability show for spectre v2
  arm64: add sysfs vulnerability show for speculative store bypass
  arm64: enable generic CPU vulnerabilites support

 arch/arm64/Kconfig                  |  1 +
 arch/arm64/include/asm/cpufeature.h | 16 +++++++
 arch/arm64/kernel/cpu_errata.c      | 84 ++++++++++++++++++++++++++++++++++++-
 arch/arm64/kernel/cpufeature.c      |  9 +---
 4 files changed, 101 insertions(+), 9 deletions(-)

-- 
2.11.0

[PATCH 1/6] arm64: kpti: move check for non-vulnerable CPUs to a function

[Mian Yousaf Kaukab]

Prepare to call it in generic cpu vulnerabilities support.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/include/asm/cpufeature.h | 16 ++++++++++++++++
 arch/arm64/kernel/cpufeature.c      |  9 +--------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 1717ba1db35d..0b0b5b3e36ba 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -530,6 +530,22 @@ void arm64_set_ssbd_mitigation(bool state);
 static inline void arm64_set_ssbd_mitigation(bool state) {}
 #endif
 
+static inline bool is_cpu_meltdown_safe(void)
+{
+	/* List of CPUs that are not vulnerable and don't need KPTI */
+	static const struct midr_range kpti_safe_list[] = {
+		MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
+		MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
+		{ /* sentinel */ }
+	};
+
+	/* Don't force KPTI for CPUs that are not vulnerable */
+	if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
+		return true;
+
+	return false;
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index e238b7932096..6a94f8bce35a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -865,12 +865,6 @@ static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */
 static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 				int scope)
 {
-	/* List of CPUs that are not vulnerable and don't need KPTI */
-	static const struct midr_range kpti_safe_list[] = {
-		MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
-		MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
-		{ /* sentinel */ }
-	};
 	char const *str = "command line option";
 
 	/*
@@ -894,8 +888,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
 		return true;
 
-	/* Don't force KPTI for CPUs that are not vulnerable */
-	if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
+	if (is_cpu_meltdown_safe())
 		return false;
 
 	/* Defer to CPU feature registers */
-- 
2.11.0

[PATCH 2/6] arm64: add sysfs vulnerability show for meltdown

[Mian Yousaf Kaukab]

Checking CSV3 support directly in case CONFIG_UNMAP_KERNEL_AT_EL0
is not enabled.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/kernel/cpu_errata.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index dec10898d688..996edb4e18ad 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -22,6 +22,7 @@
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 #include <asm/cpufeature.h>
+#include <asm/mmu.h>
 
 static bool __maybe_unused
 is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
@@ -683,3 +684,26 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 	{
 	}
 };
+
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
+
+ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	u64 pfr0;
+	u32 csv3;
+
+	if (arm64_kernel_unmapped_at_el0())
+		return sprintf(buf, "Mitigation: KPTI\n");
+
+	pfr0 = read_cpuid(ID_AA64PFR0_EL1);
+	csv3 = cpuid_feature_extract_unsigned_field(pfr0,
+			ID_AA64PFR0_CSV3_SHIFT);
+
+	if (csv3 || is_cpu_meltdown_safe())
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Vulnerable\n");
+}
+
+#endif
-- 
2.11.0

[PATCH 3/6] arm64: add sysfs vulnerability show for spectre v1

[Mian Yousaf Kaukab]

Hard-coded since patches are merged and there are no configuration
options.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/kernel/cpu_errata.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 996edb4e18ad..92616431ae4e 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -706,4 +706,10 @@ ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr,
 	return sprintf(buf, "Vulnerable\n");
 }
 
+ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+}
+
 #endif
-- 
2.11.0

[PATCH 4/6] arm64: add sysfs vulnerability show for spectre v2

[Mian Yousaf Kaukab]

Only report mitigation present if hardening callback has been
successfully installed.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/kernel/cpu_errata.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 92616431ae4e..8469d3be7b15 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -481,7 +481,8 @@ multi_entry_cap_cpu_enable(const struct arm64_cpu_capabilities *entry)
 			caps->cpu_enable(caps);
 }
 
-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+#if defined(CONFIG_HARDEN_BRANCH_PREDICTOR) || \
+	defined(CONFIG_GENERIC_CPU_VULNERABILITIES)
 
 /*
  * List of CPUs where we need to issue a psci call to
@@ -712,4 +713,35 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
 	return sprintf(buf, "Mitigation: __user pointer sanitization\n");
 }
 
+ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	u64 pfr0;
+	struct bp_hardening_data *data;
+
+	pfr0 = read_cpuid(ID_AA64PFR0_EL1);
+	if (cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_CSV2_SHIFT))
+		return sprintf(buf, "Not affected\n");
+
+	if (cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR)) {
+		/*
+		 * Hardware is vulnerable. Lets check if bp hardening callback
+		 * has been successfully installed
+		 */
+		data = arm64_get_bp_hardening_data();
+		if (data && data->fn)
+			return sprintf(buf,
+				"Mitigation: Branch predictor hardening");
+		else
+			/* For example SMCCC_VERSION_1_0 */
+			return sprintf(buf, "Vulnerable\n");
+	}
+
+	/* In case CONFIG_HARDEN_BRANCH_PREDICTOR is not enabled */
+	if (is_midr_in_range_list(read_cpuid_id(), arm64_bp_harden_smccc_cpus))
+		return sprintf(buf, "Vulnerable\n");
+
+	return sprintf(buf, "Not affected\n");
+}
+
 #endif
-- 
2.11.0

[PATCH 5/6] arm64: add sysfs vulnerability show for speculative store bypass

[Mian Yousaf Kaukab]

Return status based no ssbd_state. Return string "Unknown" in case
CONFIG_ARM64_SSBD is disabled or arch workaround2 is not available
in the firmware.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/kernel/cpu_errata.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 8469d3be7b15..8b60aa30a3fa 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -744,4 +744,24 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr,
 	return sprintf(buf, "Not affected\n");
 }
 
+ssize_t cpu_show_spec_store_bypass(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	switch (arm64_get_ssbd_state()) {
+	case ARM64_SSBD_MITIGATED:
+		return sprintf(buf, "Not affected\n");
+
+	case ARM64_SSBD_KERNEL:
+	case ARM64_SSBD_FORCE_ENABLE:
+		return sprintf(buf,
+			"Mitigation: Speculative Store Bypass disabled");
+
+	case ARM64_SSBD_FORCE_DISABLE:
+		return sprintf(buf, "Vulnerable\n");
+
+	default: /* ARM64_SSBD_UNKNOWN*/
+		return sprintf(buf, "Unknown\n");
+	}
+}
+
 #endif
-- 
2.11.0

[PATCH 6/6] arm64: enable generic CPU vulnerabilites support

[Mian Yousaf Kaukab]

Enable CPU vulnerabilty show functions for spectre_v1, spectre_v2,
meltdown and store-bypass.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 0dec01a0c81c..ffd97bc0f5d5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -84,6 +84,7 @@ config ARM64
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CLOCKEVENTS_BROADCAST
 	select GENERIC_CPU_AUTOPROBE
+	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_IRQ_MULTI_HANDLER
-- 
2.11.0

[PATCH 3/6] arm64: add sysfs vulnerability show for spectre v1

[Jeremy Linton]

From: Mian Yousaf Kaukab <ykaukab@suse.de>

spectre v1, has been mitigated, and the mitigation is
always active.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
---
 arch/arm64/kernel/cpu_errata.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 6ad715d67df8..559ecdee6fd2 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -757,3 +757,13 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 	{
 	}
 };
+
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
+
+ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+}
+
+#endif
-- 
2.17.2