Later commits will cause objtool to warn about static keys being used in .noinstr sections in order to safely defer instruction patching IPIs targeted at NOHZ_FULL CPUs.
mds_idle_clear is used in .noinstr code, and can be modified at runtime (SMT hotplug). Suppressing the text_poke_sync() IPI has little benefits for this key, as hotplug implies eventually going through takedown_cpu() -> stop_machine_cpuslocked() which is going to cause interference on all online CPUs anyway.
Mark it to let objtool know not to warn about it.
Signed-off-by: Valentin Schneider vschneid@redhat.com --- arch/x86/kernel/cpu/bugs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 47a01d4028f60..acad84dcfc3cd 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -113,8 +113,13 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb); /* Control unconditional IBPB in switch_mm() */ DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
-/* Control MDS CPU buffer clear before idling (halt, mwait) */ -DEFINE_STATIC_KEY_FALSE(mds_idle_clear); +/* + * Control MDS CPU buffer clear before idling (halt, mwait) + * + * Allowed in .noinstr as this key is updated during hotplug which comes with + * more interference than just the text patching IPI. + */ +DEFINE_STATIC_KEY_FALSE_NOINSTR(mds_idle_clear); EXPORT_SYMBOL_GPL(mds_idle_clear);
/*