x86/int3: Avoid atomic instrumentation

Use arch_atomic_*() and __READ_ONCE() to ensure nothing untoward creeps in and ruins things. That is; this is the INT3 text poke handler, strictly limit the code that runs in it, lest it inadvertenly hits yet another INT3. Reported-by: Thomas Gleixner <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Masami Hiramatsu <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Andy Lutomirski <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
ashr · Jun 11, 2020 · ef882bf · ef882bf
1 parent 4979fb5
commit ef882bf
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
@@ -1014,9 +1014,9 @@ static struct bp_patching_desc *bp_desc;
 static __always_inline
 struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp)
 {
-	struct bp_patching_desc *desc = READ_ONCE(*descp); /* rcu_dereference */
+	struct bp_patching_desc *desc = __READ_ONCE(*descp); /* rcu_dereference */
 
-	if (!desc || !atomic_inc_not_zero(&desc->refs))
+	if (!desc || !arch_atomic_inc_not_zero(&desc->refs))
 		return NULL;
 
 	return desc;
@@ -1025,7 +1025,7 @@ struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp)
 static __always_inline void put_desc(struct bp_patching_desc *desc)
 {
 	smp_mb__before_atomic();
-	atomic_dec(&desc->refs);
+	arch_atomic_dec(&desc->refs);
 }
 
 static __always_inline void *text_poke_addr(struct text_poke_loc *tp)