From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] ARM: locks: use early clobber in arch_spin_trylock
Date: Tue, 30 Jul 2013 18:57:14 +0100 [thread overview]
Message-ID: <1375207035-8072-1-git-send-email-will.deacon@arm.com> (raw)
The res variable is written before we've finished with the input
operands (namely the lock address), so ensure that we mark it as `early
clobber' to avoid unintended register sharing.
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/include/asm/spinlock.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index f8b8965..7ed43f68 100644
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -107,7 +107,7 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
" subs %1, %0, %0, ror #16\n"
" addeq %0, %0, %4\n"
" strexeq %2, %0, [%3]"
- : "=&r" (slock), "=&r" (contended), "=r" (res)
+ : "=&r" (slock), "=&r" (contended), "=&r" (res)
: "r" (&lock->slock), "I" (1 << TICKET_SHIFT)
: "cc");
} while (res);
--
1.8.2.2
next reply other threads:[~2013-07-30 17:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-30 17:57 Will Deacon [this message]
2013-07-30 17:57 ` [PATCH 2/2] ARM: rwlocks: retry trylock operation if strex fails on free lock Will Deacon
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