| Date | Tue, 19 May 2020 19:58:27 -0000 | From | "tip-bot2 for Peter Zijlstra" <> | Subject | [tip: x86/entry] x86/int3: Avoid atomic instrumentation |
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The following commit has been merged into the x86/entry branch of tip:
Commit-ID: a53a1d0435cdc2b66f41f75fa1cee31e8fe6d99e Gitweb: https://git.kernel.org/tip/a53a1d0435cdc2b66f41f75fa1cee31e8fe6d99e Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Fri, 24 Jan 2020 22:08:45 +01:00 Committer: Thomas Gleixner <tglx@linutronix.de> CommitterDate: Tue, 19 May 2020 16:04:05 +02:00
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 <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135313.517429268@linutronix.de
--- arch/x86/kernel/alternative.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 1f4cb2c..686c8ac 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -960,9 +960,9 @@ 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; @@ -971,7 +971,7 @@ 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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