sh: add working futex atomic ops on userspace addresses for smp

The version of futex.h in asm-generic should really be adapted to do
the same thing so that this hideous code does not have to be
duplicated per-arch.

Signed-off-by: Rich Felker <dalias@libc.org>

1 files changed, 59 insertions, 38 deletions

diff --git a/arch/sh/include/asm/futex.h b/arch/sh/include/asm/futex.h
index 7be39a6..d007874 100644
--- a/arch/sh/include/asm/futex.h
+++ b/arch/sh/include/asm/futex.h
@@ -7,16 +7,34 @@
 #include <linux/uaccess.h>
 #include <asm/errno.h>
 
-/* XXX: UP variants, fix for SH-4A and SMP.. */
+#if !defined(CONFIG_SMP)
 #include <asm/futex-irq.h>
+#elif defined(CONFIG_CPU_J2)
+#include <asm/futex-cas.h>
+#elif defined(CONFIG_CPU_SH4A)
+#include <asm/futex-llsc.h>
+#else
+#error SMP not supported on this configuration.
+#endif
+
+static inline int
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
+			      u32 oldval, u32 newval)
+{
+	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+		return -EFAULT;
+
+	return atomic_futex_op_cmpxchg_inatomic(uval, uaddr, oldval, newval);
+}
 
 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
 {
 	int op = (encoded_op >> 28) & 7;
 	int cmp = (encoded_op >> 24) & 15;
-	int oparg = (encoded_op << 8) >> 20;
-	int cmparg = (encoded_op << 20) >> 20;
-	int oldval = 0, ret;
+	u32 oparg = (encoded_op << 8) >> 20;
+	u32 cmparg = (encoded_op << 20) >> 20;
+	u32 oldval, newval, prev;
+	int ret;
 
 	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 		oparg = 1 << oparg;
@@ -26,26 +44,39 @@ static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
 
 	pagefault_disable();
 
-	switch (op) {
-	case FUTEX_OP_SET:
-		ret = atomic_futex_op_xchg_set(oparg, uaddr, &oldval);
-		break;
-	case FUTEX_OP_ADD:
-		ret = atomic_futex_op_xchg_add(oparg, uaddr, &oldval);
-		break;
-	case FUTEX_OP_OR:
-		ret = atomic_futex_op_xchg_or(oparg, uaddr, &oldval);
-		break;
-	case FUTEX_OP_ANDN:
-		ret = atomic_futex_op_xchg_and(~oparg, uaddr, &oldval);
-		break;
-	case FUTEX_OP_XOR:
-		ret = atomic_futex_op_xchg_xor(oparg, uaddr, &oldval);
-		break;
-	default:
-		ret = -ENOSYS;
-		break;
-	}
+	do {
+		if (op == FUTEX_OP_SET)
+			ret = oldval = 0;
+		else
+			ret = get_user(oldval, uaddr);
+
+		if (ret) break;
+
+		switch (op) {
+		case FUTEX_OP_SET:
+			newval = oparg;
+			break;
+		case FUTEX_OP_ADD:
+			newval = oldval + oparg;
+			break;
+		case FUTEX_OP_OR:
+			newval = oldval | oparg;
+			break;
+		case FUTEX_OP_ANDN:
+			newval = oldval & ~oparg;
+			break;
+		case FUTEX_OP_XOR:
+			newval = oldval ^ oparg;
+			break;
+		default:
+			ret = -ENOSYS;
+			break;
+		}
+
+		if (ret) break;
+
+		ret = futex_atomic_cmpxchg_inatomic(&prev, uaddr, oldval, newval);
+	} while (!ret && prev != oldval);
 
 	pagefault_enable();
 
@@ -53,10 +84,10 @@ static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
 		switch (cmp) {
 		case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 		case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
-		case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
-		case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
-		case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
-		case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
+		case FUTEX_OP_CMP_LT: ret = ((int)oldval < (int)cmparg); break;
+		case FUTEX_OP_CMP_GE: ret = ((int)oldval >= (int)cmparg); break;
+		case FUTEX_OP_CMP_LE: ret = ((int)oldval <= (int)cmparg); break;
+		case FUTEX_OP_CMP_GT: ret = ((int)oldval > (int)cmparg); break;
 		default: ret = -ENOSYS;
 		}
 	}
@@ -64,15 +95,5 @@ static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
 	return ret;
 }
 
-static inline int
-futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
-			      u32 oldval, u32 newval)
-{
-	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
-		return -EFAULT;
-
-	return atomic_futex_op_cmpxchg_inatomic(uval, uaddr, oldval, newval);
-}
-
 #endif /* __KERNEL__ */
 #endif /* __ASM_SH_FUTEX_H */