From: Will Deacon <will.deacon@arm.com>
Date: Mon, 12 Aug 2013 17:03:26 +0000 (+0100)
Subject: ARM: 7811/1: locks: use early clobber in arch_spin_trylock
X-Git-Tag: accepted/tizen/common/20141203.182822~1657^2~5
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=afa31d8eb86fc2f25083e675d57ac8173a98f999;p=platform%2Fkernel%2Flinux-arm64.git

ARM: 7811/1: locks: use early clobber in arch_spin_trylock

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>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

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);