From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Will Deacon <will@kernel.org>, Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] rcu: Fixup noinstr warnings
Date: Wed, 3 Jun 2020 10:48:18 +0200 [thread overview]
Message-ID: <20200603084818.GB2627@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200602193853.GF2604@hirez.programming.kicks-ass.net>
On Tue, Jun 02, 2020 at 09:38:53PM +0200, Peter Zijlstra wrote:
> That said; noinstr's __no_sanitize combined with atomic_t might be
> 'interesting', because the regular atomic things have explicit
> annotations in them. That should give validation warnings for the right
> .config, I'll have to go try -- so far I've made sure to never enable
> the *SAN stuff.
---
Subject: rcu: Fixup noinstr warnings
A KCSAN build revealed we have explicit annoations through atomic_t
usage, switch to arch_atomic_*() for the respective functions.
vmlinux.o: warning: objtool: rcu_nmi_exit()+0x4d: call to __kcsan_check_access() leaves .noinstr.text section
vmlinux.o: warning: objtool: rcu_dynticks_eqs_enter()+0x25: call to __kcsan_check_access() leaves .noinstr.text section
vmlinux.o: warning: objtool: rcu_nmi_enter()+0x4f: call to __kcsan_check_access() leaves .noinstr.text section
vmlinux.o: warning: objtool: rcu_dynticks_eqs_exit()+0x2a: call to __kcsan_check_access() leaves .noinstr.text section
vmlinux.o: warning: objtool: __rcu_is_watching()+0x25: call to __kcsan_check_access() leaves .noinstr.text section
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/rcu/tree.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c716eadc7617..162656b80db9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -250,7 +250,7 @@ static noinstr void rcu_dynticks_eqs_enter(void)
* next idle sojourn.
*/
rcu_dynticks_task_trace_enter(); // Before ->dynticks update!
- seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
+ seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
// RCU is no longer watching. Better be in extended quiescent state!
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
(seq & RCU_DYNTICK_CTRL_CTR));
@@ -274,13 +274,13 @@ static noinstr void rcu_dynticks_eqs_exit(void)
* and we also must force ordering with the next RCU read-side
* critical section.
*/
- seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
+ seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
// RCU is now watching. Better not be in an extended quiescent state!
rcu_dynticks_task_trace_exit(); // After ->dynticks update!
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!(seq & RCU_DYNTICK_CTRL_CTR));
if (seq & RCU_DYNTICK_CTRL_MASK) {
- atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks);
+ arch_atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks);
smp_mb__after_atomic(); /* _exit after clearing mask. */
}
}
@@ -313,7 +313,7 @@ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
{
struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
- return !(atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR);
+ return !(arch_atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR);
}
/*
@@ -692,6 +692,7 @@ noinstr void rcu_nmi_exit(void)
{
struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+ instrumentation_begin();
/*
* Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
* (We are exiting an NMI handler, so RCU better be paying attention
@@ -705,7 +706,6 @@ noinstr void rcu_nmi_exit(void)
* leave it in non-RCU-idle state.
*/
if (rdp->dynticks_nmi_nesting != 1) {
- instrumentation_begin();
trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2,
atomic_read(&rdp->dynticks));
WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
@@ -714,7 +714,6 @@ noinstr void rcu_nmi_exit(void)
return;
}
- instrumentation_begin();
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks));
WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
next prev parent reply other threads:[~2020-06-03 8:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 18:44 [PATCH -tip 1/2] Kconfig: Bump required compiler version of KASAN and UBSAN Marco Elver
2020-06-02 18:44 ` [PATCH -tip 2/2] compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr Marco Elver
2020-06-02 18:49 ` Nick Desaulniers
2020-06-02 18:55 ` Marco Elver
2020-06-03 14:06 ` Miguel Ojeda
2020-06-03 13:35 ` Andrey Konovalov
2020-06-02 18:53 ` [PATCH -tip 1/2] Kconfig: Bump required compiler version of KASAN and UBSAN Andrey Konovalov
2020-06-02 19:07 ` Marco Elver
2020-06-02 19:12 ` Andrey Konovalov
2020-06-02 18:57 ` Nick Desaulniers
2020-06-02 19:01 ` Marco Elver
2020-06-02 19:19 ` Peter Zijlstra
2020-06-02 19:25 ` Marco Elver
2020-06-02 19:38 ` Peter Zijlstra
2020-06-02 19:59 ` Nick Desaulniers
2020-06-03 8:48 ` Peter Zijlstra [this message]
2020-06-03 9:59 ` [PATCH] rcu: Fixup noinstr warnings Paul E. McKenney
2020-06-03 10:52 ` Peter Zijlstra
2020-06-03 16:29 ` Paul E. McKenney
2020-06-03 13:35 ` [PATCH -tip 1/2] Kconfig: Bump required compiler version of KASAN and UBSAN Andrey Konovalov
2020-06-04 5:59 ` Marco Elver
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