From: Kees Cook <keescook@chromium.org>
Date: Wed, 13 Jul 2022 14:38:19 -0700
Subject: x86/alternative: Report missing return thunk details
Git-commit: 65cdf0d623bedf0e069bb64ed52e8bb20105e2ba
Patch-mainline: v5.19-rc8
References: git-fixes
Debugging missing return thunks is easier if we can see where they're
happening.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/Ys66hwtFcGbYmoiZ@hirez.programming.kicks-ass.net/
Acked-by: Nikolay Borisov <nik.borisov@suse.com>
---
arch/x86/kernel/alternative.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index d6858533e6e5..62f6b8b7c4a5 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -555,7 +555,9 @@ void __init_or_module noinline apply_returns(s32 *start, s32 *end)
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",