Implements futex op support and makes futex cmpxchg atomic.
Tested on 64-bit SMP kernel running on 2 x PA8700s.
Signed-off-by: Carlos O'Donell <carlos@xxxxxxxxxxxxxxxx>
---
futex.h | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 59 insertions(+), 5 deletions(-)
diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h
index 67a33cc..94f2f4d 100644
--- a/arch/parisc/include/asm/futex.h
+++ b/arch/parisc/include/asm/futex.h
@@ -5,11 +5,14 @@
#include <linux/futex.h>
#include <linux/uaccess.h>
+#include <asm/atomic.h>
#include <asm/errno.h>
static inline int
futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
{
+ unsigned long int flags;
+ u32 val;
int op = (encoded_op >> 28) & 7;
int cmp = (encoded_op >> 24) & 15;
int oparg = (encoded_op << 8) >> 20;
@@ -23,16 +26,53 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
pagefault_disable();
+ _atomic_spin_lock_irqsave (uaddr, flags);
+
switch (op) {
case FUTEX_OP_SET:
+ /* *(int *)UADDR2 = OPARG; */
+ ret = get_user (oldval, uaddr);
+ if (!ret)
+ ret = put_user (oparg, uaddr);
+ break;
case FUTEX_OP_ADD:
+ /* *(int *)UADDR2 += OPARG; */
+ ret = get_user (oldval, uaddr);
+ if (!ret) {
+ val = oldval + oparg;
+ ret = put_user (val, uaddr);
+ }
+ break;
case FUTEX_OP_OR:
+ /* *(int *)UADDR2 |= OPARG; */
+ ret = get_user (oldval, uaddr);
+ if (!ret) {
+ val = oldval | oparg;
+ ret = put_user (val, uaddr);
+ }
+ break;
case FUTEX_OP_ANDN:
+ /* *(int *)UADDR2 &= ~OPARG; */
+ ret = get_user (oldval, uaddr);
+ if (!ret) {
+ val = oldval & ~oparg;
+ ret = put_user (val, uaddr);
+ }
+ break;
case FUTEX_OP_XOR:
+ /* *(int *)UADDR2 ^= OPARG; */
+ ret = get_user (oldval, uaddr);
+ if (!ret) {
+ val = oldval ^ oparg;
+ ret = put_user (val, uaddr);
+ }
+ break;
default:
ret = -ENOSYS;
}
+ _atomic_spin_unlock_irqrestore (uaddr, flags);
+
pagefault_enable();
if (!ret) {
@@ -54,7 +94,9 @@ static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
+ int ret;
u32 val;
+ unsigned long flags;
/* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
* our gateway page, and causes no end of trouble...
@@ -65,12 +107,24 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
- if (get_user(val, uaddr))
- return -EFAULT;
- if (val == oldval && put_user(newval, uaddr))
- return -EFAULT;
+ /* HPPA has no cmpxchg in hardware and therefore the
+ * best we can do here is use an array of locks. The
+ * lock selected is based on a hash of the userspace
+ * address. This should scale to a couple of CPUs.
+ */
+
+ _atomic_spin_lock_irqsave (uaddr, flags);
+
+ ret = get_user(val, uaddr);
+
+ if (!ret && val == oldval)
+ ret = put_user (newval, uaddr);
+
*uval = val;
- return 0;
+
+ _atomic_spin_unlock_irqrestore (uaddr, flags);
+
+ return ret;
}
#endif /*__KERNEL__*/
--
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