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From e288c57f82b662d0bc2d8fcf64e78e23c4c77919 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 7 Jan 2018 22:48:00 +0100
Subject: [PATCH 053/102] sysfs/cpu: Add vulnerability folder
commit 87590ce6e373d1a5401f6539f0c59ef92dd924a9 upstream.
As the meltdown/spectre problem affects several CPU architectures, it makes
sense to have common way to express whether a system is affected by a
particular vulnerability or not. If affected the way to express the
mitigation should be common as well.
Create /sys/devices/system/cpu/vulnerabilities folder and files for
meltdown, spectre_v1 and spectre_v2.
Allow architectures to override the show function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lkml.kernel.org/r/20180107214913.096657732@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/ABI/testing/sysfs-devices-system-cpu | 16 ++++++++
drivers/base/Kconfig | 3 ++
drivers/base/cpu.c | 48 ++++++++++++++++++++++
include/linux/cpu.h | 7 ++++
4 files changed, 74 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 4987417..8b30a48 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -350,3 +350,19 @@ Contact: Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
Description: AArch64 CPU registers
'identification' directory exposes the CPU ID registers for
identifying model and revision of the CPU.
+
+What: /sys/devices/system/cpu/vulnerabilities
+ /sys/devices/system/cpu/vulnerabilities/meltdown
+ /sys/devices/system/cpu/vulnerabilities/spectre_v1
+ /sys/devices/system/cpu/vulnerabilities/spectre_v2
+Date: Januar 2018
+Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description: Information about CPU vulnerabilities
+
+ The files are named after the code names of CPU
+ vulnerabilities. The output of those files reflects the
+ state of the CPUs in the system. Possible output values:
+
+ "Not affected" CPU is not affected by the vulnerability
+ "Vulnerable" CPU is affected and no mitigation in effect
+ "Mitigation: $M" CPU is affetcted and mitigation $M is in effect
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index d02e7c0..0651010 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -235,6 +235,9 @@ config GENERIC_CPU_DEVICES
config GENERIC_CPU_AUTOPROBE
bool
+config GENERIC_CPU_VULNERABILITIES
+ bool
+
config SOC_BUS
bool
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 4c28e1a..56b6c85 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -499,10 +499,58 @@ static void __init cpu_dev_register_generic(void)
#endif
}
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
+
+ssize_t __weak cpu_show_meltdown(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "Not affected\n");
+}
+
+ssize_t __weak cpu_show_spectre_v1(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "Not affected\n");
+}
+
+ssize_t __weak cpu_show_spectre_v2(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "Not affected\n");
+}
+
+static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
+static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
+static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
+
+static struct attribute *cpu_root_vulnerabilities_attrs[] = {
+ &dev_attr_meltdown.attr,
+ &dev_attr_spectre_v1.attr,
+ &dev_attr_spectre_v2.attr,
+ NULL
+};
+
+static const struct attribute_group cpu_root_vulnerabilities_group = {
+ .name = "vulnerabilities",
+ .attrs = cpu_root_vulnerabilities_attrs,
+};
+
+static void __init cpu_register_vulnerabilities(void)
+{
+ if (sysfs_create_group(&cpu_subsys.dev_root->kobj,
+ &cpu_root_vulnerabilities_group))
+ pr_err("Unable to register CPU vulnerabilities\n");
+}
+
+#else
+static inline void cpu_register_vulnerabilities(void) { }
+#endif
+
void __init cpu_dev_init(void)
{
if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
panic("Failed to register CPU subsystem");
cpu_dev_register_generic();
+ cpu_register_vulnerabilities();
}
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index e571128..2f475ad 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -44,6 +44,13 @@ extern void cpu_remove_dev_attr(struct device_attribute *attr);
extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);
+extern ssize_t cpu_show_meltdown(struct device *dev,
+ struct device_attribute *attr, char *buf);
+extern ssize_t cpu_show_spectre_v1(struct device *dev,
+ struct device_attribute *attr, char *buf);
+extern ssize_t cpu_show_spectre_v2(struct device *dev,
+ struct device_attribute *attr, char *buf);
+
extern __printf(4, 5)
struct device *cpu_device_create(struct device *parent, void *drvdata,
const struct attribute_group **groups,
--
2.7.4
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