Commit d424986f authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390: add sysfs attributes for spectre 



Set CONFIG_GENERIC_CPU_VULNERABILITIES and provide the two functions
cpu_show_spectre_v1 and cpu_show_spectre_v2 to report the spectre
mitigations.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent bc035599

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -120,6 +120,7 @@ config S390 
	select GENERIC_CLOCKEVENTS

	select GENERIC_CPU_AUTOPROBE

	select GENERIC_CPU_DEVICES if !SMP

	select GENERIC_CPU_VULNERABILITIES

	select GENERIC_FIND_FIRST_BIT

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_TIME_VSYSCALL

arch/s390/kernel/nospec-branch.c

+19 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/module.h>

#include <linux/device.h>

#include <asm/nospec-branch.h>



static int __init nobp_setup_early(char *str)
@@ -42,6 +43,24 @@ static int __init nospec_report(void) 
}

arch_initcall(nospec_report);



#ifdef CONFIG_SYSFS

ssize_t cpu_show_spectre_v1(struct device *dev,

			    struct device_attribute *attr, char *buf)

{

	return sprintf(buf, "Mitigation: __user pointer sanitization\n");

}



ssize_t cpu_show_spectre_v2(struct device *dev,

			    struct device_attribute *attr, char *buf)

{

	if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable)

		return sprintf(buf, "Mitigation: execute trampolines\n");

	if (__test_facility(82, S390_lowcore.alt_stfle_fac_list))

		return sprintf(buf, "Mitigation: limited branch prediction.\n");

	return sprintf(buf, "Vulnerable\n");

}

#endif



#ifdef CONFIG_EXPOLINE



int nospec_disable = IS_ENABLED(CONFIG_EXPOLINE_OFF);