From: Mark Rutland <mark.rutland@arm.com>
To: linux-kernel@vger.kernel.org
Cc: benh@kernel.crashing.org, boqun.feng@gmail.com, bp@alien8.de,
catalin.marinas@arm.com, dvyukov@google.com, elver@google.com,
ink@jurassic.park.msu.ru, jonas@southpole.se,
juri.lelli@redhat.com, linux@armlinux.org.uk, luto@kernel.org,
mark.rutland@arm.com, mattst88@gmail.com, mingo@redhat.com,
monstr@monstr.eu, mpe@ellerman.id.au, paulmck@kernel.org,
paulus@samba.org, peterz@infradead.org, rth@twiddle.net,
shorne@gmail.com, stefan.kristiansson@saunalahti.fi,
tglx@linutronix.de, vincent.guittot@linaro.org, will@kernel.org
Subject: [RFC PATCH 02/10] entry: snapshot thread flags
Date: Wed, 9 Jun 2021 13:19:53 +0100 [thread overview]
Message-ID: <20210609122001.18277-3-mark.rutland@arm.com> (raw)
In-Reply-To: <20210609122001.18277-1-mark.rutland@arm.com>
Some thread flags can be set remotely, and so even when IRQs are
disabled, the flags can change under our feet. Generally this is
unlikely to cause a problem in practice, but it is somewhat unsound, and
KCSAN will legitimately warn that there is a data race.
To avoid such issues, we should snapshot the flags prior to using them.
Let's use the new helpers to do so in the common entry code.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/entry-kvm.h | 2 +-
kernel/entry/common.c | 4 ++--
kernel/entry/kvm.c | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/entry-kvm.h b/include/linux/entry-kvm.h
index 8b2b1d68b954..bc487dffb803 100644
--- a/include/linux/entry-kvm.h
+++ b/include/linux/entry-kvm.h
@@ -70,7 +70,7 @@ static inline void xfer_to_guest_mode_prepare(void)
*/
static inline bool __xfer_to_guest_mode_work_pending(void)
{
- unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
+ unsigned long ti_work = read_thread_flags();
return !!(ti_work & XFER_TO_GUEST_MODE_WORK);
}
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index a0b3b04fb596..3147a1f2ed74 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -188,7 +188,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
/* Check if any of the above work has queued a deferred wakeup */
rcu_nocb_flush_deferred_wakeup();
- ti_work = READ_ONCE(current_thread_info()->flags);
+ ti_work = read_thread_flags();
}
/* Return the latest work state for arch_exit_to_user_mode() */
@@ -197,7 +197,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
static void exit_to_user_mode_prepare(struct pt_regs *regs)
{
- unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
+ unsigned long ti_work = read_thread_flags();
lockdep_assert_irqs_disabled();
diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c
index 49972ee99aff..96d476e06c77 100644
--- a/kernel/entry/kvm.c
+++ b/kernel/entry/kvm.c
@@ -26,7 +26,7 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
if (ret)
return ret;
- ti_work = READ_ONCE(current_thread_info()->flags);
+ ti_work = read_thread_flags();
} while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched());
return 0;
}
@@ -43,7 +43,7 @@ int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu)
* disabled in the inner loop before going into guest mode. No need
* to disable interrupts here.
*/
- ti_work = READ_ONCE(current_thread_info()->flags);
+ ti_work = read_thread_flags();
if (!(ti_work & XFER_TO_GUEST_MODE_WORK))
return 0;
--
2.11.0
next prev parent reply other threads:[~2021-06-09 12:20 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 12:19 [RFC PATCH 00/10] thread_info: use helpers to snapshot thread flags Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 01/10] thread_info: add " Mark Rutland
2021-06-10 9:01 ` Marco Elver
2021-06-11 9:17 ` Mark Rutland
2021-06-19 22:28 ` Thomas Gleixner
2021-06-21 8:29 ` Mark Rutland
2021-06-09 12:19 ` Mark Rutland [this message]
2021-06-09 12:19 ` [RFC PATCH 03/10] sched: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 04/10] alpha: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 05/10] arm: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 06/10] arm64: read " Mark Rutland
2021-06-16 22:07 ` kernel test robot
2021-06-09 12:19 ` [RFC PATCH 07/10] microblaze: snapshot " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 08/10] openrisc: " Mark Rutland
2021-06-10 19:14 ` Stafford Horne
2021-06-09 12:20 ` [RFC PATCH 09/10] powerpc: " Mark Rutland
2021-06-15 13:18 ` Michael Ellerman
2021-06-21 8:46 ` Mark Rutland
2021-06-09 12:20 ` [RFC PATCH 10/10] x86: " Mark Rutland
2021-06-19 22:30 ` Thomas Gleixner
2021-06-21 8:35 ` Mark Rutland
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