4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Martin Schwidefsky schwidefsky@de.ibm.com
[ Upstream commit bc035599718412cfba9249aa713f90ef13f13ee9 ]
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: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/kernel/nospec-branch.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/arch/s390/kernel/nospec-branch.c +++ b/arch/s390/kernel/nospec-branch.c @@ -33,6 +33,16 @@ static int __init nospec_setup_early(cha } 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);