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    Subject[PATCH 4.14 58/80] s390: add sysfs attributes for spectre
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Martin Schwidefsky <schwidefsky@de.ibm.com>


    [ Upstream commit d424986f1d6b16079b3231db0314923f4f8deed1 ]

    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: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/s390/Kconfig | 1 +
    arch/s390/kernel/nospec-branch.c | 19 +++++++++++++++++++
    2 files changed, 20 insertions(+)

    --- a/arch/s390/Kconfig
    +++ b/arch/s390/Kconfig
    @@ -121,6 +121,7 @@ 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
    --- a/arch/s390/kernel/nospec-branch.c
    +++ b/arch/s390/kernel/nospec-branch.c
    @@ -1,5 +1,6 @@
    // SPDX-License-Identifier: GPL-2.0
    #include <linux/module.h>
    +#include <linux/device.h>
    #include <asm/facility.h>
    #include <asm/nospec-branch.h>

    @@ -43,6 +44,24 @@ 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);

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