Commit ef882bfe authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505135313.517429268@linutronix.de


parent 4979fb53
......@@ -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)
......
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