[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 05 May 2020 15:49:28 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
Andy Lutomirski <luto@...nel.org>,
Alexandre Chartre <alexandre.chartre@...cle.com>,
Frederic Weisbecker <frederic@...nel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Joel Fernandes <joel@...lfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Brian Gerst <brgerst@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Will Deacon <will@...nel.org>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V4 part 4 02/24] x86/int3: Avoid atomic instrumentation
From: Peter Zijlstra <peterz@...radead.org>
Use arch_atomic_*() and READ_ONCE_NOCHECK() 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@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
arch/x86/kernel/alternative.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- 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_NOCHECK(*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(st
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)
Powered by blists - more mailing lists