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| author |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2018-05-08 15:14:48 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2018-07-18 08:32:17 +0200 |
| commit | aeaf7002a76c8da60c0f503badcbddc07650678c (patch) | |
| tree | 4a8bf8d1dd9ed365d8cdb4540062f81639833ba9 /arch/s390/kernel | |
| parent | s390/chsc: fix packed-not-aligned warnings (diff) | |
| download | linux-dev-aeaf7002a76c8da60c0f503badcbddc07650678c.tar.xz linux-dev-aeaf7002a76c8da60c0f503badcbddc07650678c.zip | |
s390: detect etoken facility
Detect and report the etoken facility. With spectre_v2=auto or
CONFIG_EXPOLINE_AUTO=y automatically disable expolines and use
the full branch prediction mode for the kernel.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel')
| -rw-r--r-- | arch/s390/kernel/nospec-branch.c | 12 | ||||
| -rw-r--r-- | arch/s390/kernel/nospec-sysfs.c | 2 |
2 files changed, 13 insertions, 1 deletions
diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c index 18ae7b9c71d6..bdddaae96559 100644 --- a/arch/s390/kernel/nospec-branch.c +++ b/arch/s390/kernel/nospec-branch.c @@ -35,6 +35,8 @@ early_param("nospec", nospec_setup_early); static int __init nospec_report(void) { + if (test_facility(156)) + pr_info("Spectre V2 mitigation: etokens\n"); if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable) pr_info("Spectre V2 mitigation: execute trampolines\n"); if (__test_facility(82, S390_lowcore.alt_stfle_fac_list)) @@ -56,7 +58,15 @@ early_param("nospectre_v2", nospectre_v2_setup_early); void __init nospec_auto_detect(void) { - if (IS_ENABLED(CC_USING_EXPOLINE)) { + if (test_facility(156)) { + /* + * The machine supports etokens. + * Disable expolines and disable nobp. + */ + if (IS_ENABLED(CC_USING_EXPOLINE)) + nospec_disable = 1; + __clear_facility(82, S390_lowcore.alt_stfle_fac_list); + } else if (IS_ENABLED(CC_USING_EXPOLINE)) { /* * The kernel has been compiled with expolines. * Keep expolines enabled and disable nobp. diff --git a/arch/s390/kernel/nospec-sysfs.c b/arch/s390/kernel/nospec-sysfs.c index 8affad5f18cb..e30e580ae362 100644 --- a/arch/s390/kernel/nospec-sysfs.c +++ b/arch/s390/kernel/nospec-sysfs.c @@ -13,6 +13,8 @@ ssize_t cpu_show_spectre_v1(struct device *dev, ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf) { + if (test_facility(156)) + return sprintf(buf, "Mitigation: etokens\n"); 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)) |