Objtool now warns about it:

  vmlinux.o: warning: objtool: .altinstr_replacement+0x28e1: call to warn_thunk_thunk() leaves .noinstr.text section

Mark it noinstr.

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
---
 arch/x86/entry/entry.S     | 3 ++-
 arch/x86/kernel/cpu/bugs.c | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
index 6ba2b3adcef0f..e76560f86b332 100644
--- a/arch/x86/entry/entry.S
+++ b/arch/x86/entry/entry.S
@@ -40,6 +40,8 @@ SYM_FUNC_START(__WARN_trap)
 SYM_FUNC_END(__WARN_trap)
 EXPORT_SYMBOL(__WARN_trap)
 
+THUNK warn_thunk_thunk, __warn_thunk
+
 .popsection
 
 /*
@@ -60,7 +62,6 @@ EXPORT_SYMBOL_FOR_KVM(x86_verw_sel);
 
 .popsection
 
-THUNK warn_thunk_thunk, __warn_thunk
 
 /*
  * Clang's implementation of TLS stack cookies requires the variable in
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d0a2847a4bb05..1ddf9355a37af 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -3732,7 +3732,7 @@ ssize_t cpu_show_vmscape(struct device *dev, struct device_attribute *attr, char
 }
 #endif
 
-void __warn_thunk(void)
+void noinstr __warn_thunk(void)
 {
 	WARN_ONCE(1, "Unpatched return thunk in use. This should not happen!\n");
 }
-- 
2.52.0