[PATCH 5.15 88/89] um: Add missing apply_returns()

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

commit 564d998106397394b6aad260f219b882b3347e62 upstream.

Implement apply_returns() stub for UM, just like all the other patching
routines.

Fixes: 15e67227c49a ("x86: Undo return-thunk damage")
Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx)
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/Ys%2Ft45l%2FgarIrD0u@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/um/kernel/um_arch.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -425,6 +425,10 @@ void apply_retpolines(s32 *start, s32 *e
 {
 }
 
+void apply_returns(s32 *start, s32 *end)
+{
+}
+
 void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
 {
 }