[PATCH 5.18 153/158] x86/alternative: Report missing return thunk details
From: Greg Kroah-Hartman
Date: Wed Jul 27 2022 - 13:46:17 EST
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit 65cdf0d623bedf0e069bb64ed52e8bb20105e2ba upstream.
Debugging missing return thunks is easier if we can see where they're
happening.
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/Ys66hwtFcGbYmoiZ@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/alternative.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -555,7 +555,9 @@ void __init_or_module noinline apply_ret
dest = addr + insn.length + insn.immediate.value;
if (__static_call_fixup(addr, op, dest) ||
- WARN_ON_ONCE(dest != &__x86_return_thunk))
+ WARN_ONCE(dest != &__x86_return_thunk,
+ "missing return thunk: %pS-%pS: %*ph",
+ addr, dest, 5, addr))
continue;
DPRINTK("return thunk at: %pS (%px) len: %d to: %pS",