[PATCH 3.10 28/85] ARM: 7811/1: locks: use early clobber in arch_spin_trylock

Greg Kroah-Hartman
2014-03-21T00:39:07Z

From: Will Deacon <will.deacon@arm.com>

commit afa31d8eb86fc2f25083e675d57ac8173a98f999 upstream.

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>
Cc: Wang Weidong <wangweidong1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm/include/asm/spinlock.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- 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
" 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);