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Commit 68cb884e authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Greg Kroah-Hartman
Browse files

s390: report spectre mitigation via syslog 



[ Upstream commit bc035599 ]

Add a boot message if either of the spectre defenses is active.
The message is
    "Spectre V2 mitigation: execute trampolines."
or  "Spectre V2 mitigation: limited branch prediction."

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 719b84c9

arch/s390/kernel/nospec-branch.c

+10 −0
Original line number Diff line number Diff line
@@ -33,6 +33,16 @@ static int __init nospec_setup_early(char *str) 
}

early_param("nospec", nospec_setup_early);



static int __init nospec_report(void)

{

	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))

		pr_info("Spectre V2 mitigation: limited branch prediction.\n");

	return 0;

}

arch_initcall(nospec_report);



#ifdef CONFIG_EXPOLINE



int nospec_disable = IS_ENABLED(CONFIG_EXPOLINE_OFF);