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authorPaul Mackerras <paulus@samba.org>2009-04-13 14:09:09 +0000
committerPaul Mackerras <paulus@samba.org>2009-04-15 15:23:53 +1000
commit306a82881b14d950d59e0b59a55093a07d82aa9a (patch)
tree73add71069ebf9572f898c0cc9ea6b889f1a7905
parentc58dc575f3c8bdc69fb868ec51e1c80ee7cae5e7 (diff)
powerpc: Fix data-corrupting bug in __futex_atomic_op
Richard Henderson pointed out that the powerpc __futex_atomic_op has a bug: it will write the wrong value if the stwcx. fails and it has to retry the lwarx/stwcx. loop, since 'oparg' will have been overwritten by the result from the first time around the loop. This happens because it uses the same register for 'oparg' (an input) as it uses for the result. This fixes it by using separate registers for 'oparg' and 'ret'. Cc: stable@kernel.org Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/include/asm/futex.h12
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h
index 6d406c5c5de4..9696cc36d2dc 100644
--- a/arch/powerpc/include/asm/futex.h
+++ b/arch/powerpc/include/asm/futex.h
@@ -27,7 +27,7 @@
PPC_LONG "1b,4b,2b,4b\n" \
".previous" \
: "=&r" (oldval), "=&r" (ret) \
- : "b" (uaddr), "i" (-EFAULT), "1" (oparg) \
+ : "b" (uaddr), "i" (-EFAULT), "r" (oparg) \
: "cr0", "memory")
static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
@@ -47,19 +47,19 @@ static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
switch (op) {
case FUTEX_OP_SET:
- __futex_atomic_op("", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("mr %1,%4\n", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
- __futex_atomic_op("add %1,%0,%1\n", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("add %1,%0,%4\n", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_OR:
- __futex_atomic_op("or %1,%0,%1\n", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("or %1,%0,%4\n", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ANDN:
- __futex_atomic_op("andc %1,%0,%1\n", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("andc %1,%0,%4\n", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_XOR:
- __futex_atomic_op("xor %1,%0,%1\n", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("xor %1,%0,%4\n", ret, oldval, uaddr, oparg);
break;
default:
ret = -ENOSYS;