Commit 87590ce6 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

sysfs/cpu: Add vulnerability folder 



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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarKonrad 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
parent 99c6fa25

Documentation/ABI/testing/sysfs-devices-system-cpu

+16 −0
Original line number Diff line number Diff line
@@ -373,3 +373,19 @@ Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 
Description:	information about CPUs heterogeneity.



		cpu_capacity: capacity of 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

drivers/base/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -235,6 +235,9 @@ config GENERIC_CPU_DEVICES 
config GENERIC_CPU_AUTOPROBE

	bool



config GENERIC_CPU_VULNERABILITIES

	bool



config SOC_BUS

	bool

	select GLOB

drivers/base/cpu.c

+48 −0
Original line number Diff line number Diff line
@@ -501,10 +501,58 @@ 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();

}

include/linux/cpu.h

+7 −0
Original line number Diff line number Diff line
@@ -47,6 +47,13 @@ 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,

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