linux-kernel - [PATCH v4 07/19] ARC: rwlock: disable interrupts in !LLSC variant

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1450228238-4499-8-git-send-email-noamc@ezchip.com>
Date:	Wed, 16 Dec 2015 03:10:26 +0200
From:	Noam Camus <noamc@...hip.com>
To:	<linux-snps-arc@...ts.infradead.org>
CC:	<linux-kernel@...r.kernel.org>, <cmetcalf@...hip.com>,
	<daniel.lezcano@...aro.org>, Noam Camus <noamc@...hip.com>
Subject: [PATCH v4 07/19] ARC: rwlock: disable interrupts in !LLSC variant

From: Noam Camus <noamc@...hip.com>

If we hold rwlock and interrupt occures we may
end up spinning on it for ever during softirq.
Note that this lock is an internal lock
and since the lock is free to be used from any context,
the lock needs to be IRQ-safe.

Below you may see an example for interrupt we get while
nl_table_lock is holding its rw->lock_mutex and we spinned
on it for ever.

The concept for the fix was taken from SPARC.

[2015-05-12 19:16:12] Stack Trace:
[2015-05-12 19:16:12]   arc_unwind_core+0xb8/0x11c
[2015-05-12 19:16:12]   dump_stack+0x68/0xac
[2015-05-12 19:16:12]   _raw_read_lock+0xa8/0xac
[2015-05-12 19:16:12]   netlink_broadcast_filtered+0x56/0x35c
[2015-05-12 19:16:12]   nlmsg_notify+0x42/0xa4
[2015-05-12 19:16:13]   neigh_update+0x1fe/0x44c
[2015-05-12 19:16:13]   neigh_event_ns+0x40/0xa4
[2015-05-12 19:16:13]   arp_process+0x46e/0x5a8
[2015-05-12 19:16:13]   __netif_receive_skb_core+0x358/0x500
[2015-05-12 19:16:13]   process_backlog+0x92/0x154
[2015-05-12 19:16:13]   net_rx_action+0xb8/0x188
[2015-05-12 19:16:13]   __do_softirq+0xda/0x1d8
[2015-05-12 19:16:14]   irq_exit+0x8a/0x8c
[2015-05-12 19:16:14]   arch_do_IRQ+0x6c/0xa8
[2015-05-12 19:16:14]   handle_interrupt_level1+0xe4/0xf0

Signed-off-by: Noam Camus <noamc@...hip.com>
Acked-by: Peter Zijlstra <peterz@...radead.org>
---
 arch/arc/include/asm/spinlock.h |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h
index db8c59d..800e7c4 100644
--- a/arch/arc/include/asm/spinlock.h
+++ b/arch/arc/include/asm/spinlock.h
@@ -610,7 +610,9 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
 static inline int arch_read_trylock(arch_rwlock_t *rw)
 {
 	int ret = 0;
+	unsigned long flags;
 
+	local_irq_save(flags);
 	arch_spin_lock(&(rw->lock_mutex));
 
 	/*
@@ -623,6 +625,7 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
 	}
 
 	arch_spin_unlock(&(rw->lock_mutex));
+	local_irq_restore(flags);
 
 	smp_mb();
 	return ret;
@@ -632,7 +635,9 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
 static inline int arch_write_trylock(arch_rwlock_t *rw)
 {
 	int ret = 0;
+	unsigned long flags;
 
+	local_irq_save(flags);
 	arch_spin_lock(&(rw->lock_mutex));
 
 	/*
@@ -646,6 +651,7 @@ static inline int arch_write_trylock(arch_rwlock_t *rw)
 		ret = 1;
 	}
 	arch_spin_unlock(&(rw->lock_mutex));
+	local_irq_restore(flags);
 
 	return ret;
 }
@@ -664,16 +670,24 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
 
 static inline void arch_read_unlock(arch_rwlock_t *rw)
 {
+	unsigned long flags;
+
+	local_irq_save(flags);
 	arch_spin_lock(&(rw->lock_mutex));
 	rw->counter++;
 	arch_spin_unlock(&(rw->lock_mutex));
+	local_irq_restore(flags);
 }
 
 static inline void arch_write_unlock(arch_rwlock_t *rw)
 {
+	unsigned long flags;
+
+	local_irq_save(flags);
 	arch_spin_lock(&(rw->lock_mutex));
 	rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
 	arch_spin_unlock(&(rw->lock_mutex));
+	local_irq_restore(flags);
 }
 
 #endif
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/