[PATCH v6 17/29] x86/speculation/mds: Mark cpu_buf_idle_clear key as allowed in .noinstr

[Valentin Schneider]

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.

cpu_buf_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 at redhat.com>
---
 arch/x86/kernel/cpu/bugs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 36dcfc5105be9..3aca329a853b5 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -182,7 +182,7 @@ DEFINE_STATIC_KEY_FALSE(switch_vcpu_ibpb);
 EXPORT_SYMBOL_GPL(switch_vcpu_ibpb);
 
 /* Control CPU buffer clear before idling (halt, mwait) */
-DEFINE_STATIC_KEY_FALSE(cpu_buf_idle_clear);
+DEFINE_STATIC_KEY_FALSE_NOINSTR(cpu_buf_idle_clear);
 EXPORT_SYMBOL_GPL(cpu_buf_idle_clear);
 
 /*
-- 
2.51.0