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>

arch/sh/include/asm/futex-cas.h

+#ifndef __ASM_SH_FUTEX_CAS_H
+#define __ASM_SH_FUTEX_CAS_H
+
+static inline int atomic_futex_op_cmpxchg_inatomic(u32 *uval,
+						   u32 __user *uaddr,
+						   u32 oldval, u32 newval)
+{
+	int err = 0;
+	__asm__ __volatile__(
+		"1:\n\t"
+		"cas.l	%2, %1, @r0\n"
+		"2:\n\t"
+#ifdef CONFIG_MMU
+		".section	.fixup,\"ax\"\n"
+		"3:\n\t"
+		"mov.l	4f, %0\n\t"
+		"jmp	@%0\n\t"
+		" mov	%3, %0\n\t"
+		".balign	4\n"
+		"4:	.long	2b\n\t"
+		".previous\n"
+		".section	__ex_table,\"a\"\n\t"
+		".long	1b, 3b\n\t"
+		".previous"
+#endif
+		:"+r" (err), "+r" (newval)
+		:"r" (oldval), "i" (-EFAULT), "z" (uaddr)
+		:"t", "memory");
+	if (err) return err;
+	*uval = newval;
+	return 0;
+}
+
+#endif /* __ASM_SH_FUTEX_CAS_H */

arch/sh/include/asm/futex-irq.h

 #ifndef __ASM_SH_FUTEX_IRQ_H
 #define __ASM_SH_FUTEX_IRQ_H
 
-
-static inline int atomic_futex_op_xchg_set(int oparg, u32 __user *uaddr,
-					   int *oldval)
-{
-	unsigned long flags;
-	int ret;
-
-	local_irq_save(flags);
-
-	ret = get_user(*oldval, uaddr);
-	if (!ret)
-		ret = put_user(oparg, uaddr);
-
-	local_irq_restore(flags);
-
-	return ret;
-}
-
-static inline int atomic_futex_op_xchg_add(int oparg, u32 __user *uaddr,
-					   int *oldval)
-{
-	unsigned long flags;
-	int ret;
-
-	local_irq_save(flags);
-
-	ret = get_user(*oldval, uaddr);
-	if (!ret)
-		ret = put_user(*oldval + oparg, uaddr);
-
-	local_irq_restore(flags);
-
-	return ret;
-}
-
-static inline int atomic_futex_op_xchg_or(int oparg, u32 __user *uaddr,
-					  int *oldval)
-{
-	unsigned long flags;
-	int ret;
-
-	local_irq_save(flags);
-
-	ret = get_user(*oldval, uaddr);
-	if (!ret)
-		ret = put_user(*oldval | oparg, uaddr);
-
-	local_irq_restore(flags);
-
-	return ret;
-}
-
-static inline int atomic_futex_op_xchg_and(int oparg, u32 __user *uaddr,
-					   int *oldval)
-{
-	unsigned long flags;
-	int ret;
-
-	local_irq_save(flags);
-
-	ret = get_user(*oldval, uaddr);
-	if (!ret)
-		ret = put_user(*oldval & oparg, uaddr);
-
-	local_irq_restore(flags);
-
-	return ret;
-}
-
-static inline int atomic_futex_op_xchg_xor(int oparg, u32 __user *uaddr,
-					   int *oldval)
-{
-	unsigned long flags;
-	int ret;
-
-	local_irq_save(flags);
-
-	ret = get_user(*oldval, uaddr);
-	if (!ret)
-		ret = put_user(*oldval ^ oparg, uaddr);
-
-	local_irq_restore(flags);
-
-	return ret;
-}
-
 static inline int atomic_futex_op_cmpxchg_inatomic(u32 *uval,
 						   u32 __user *uaddr,
 						   u32 oldval, u32 newval)

arch/sh/include/asm/futex-llsc.h

+#ifndef __ASM_SH_FUTEX_LLSC_H
+#define __ASM_SH_FUTEX_LLSC_H
+
+static inline int atomic_futex_op_cmpxchg_inatomic(u32 *uval,
+						   u32 __user *uaddr,
+						   u32 oldval, u32 newval)
+{
+	int err = 0;
+	__asm__ __volatile__(
+		"synco\n"
+		"1:\n\t"
+		"movli.l	@%2, r0\n\t"
+		"mov	r0, %1\n\t"
+		"cmp/eq	%1, %4\n\t"
+		"bf	2f\n\t"
+		"mov	%5, r0\n\t"
+		"movco.l	r0, @%2\n\t"
+		"bf	1b\n"
+		"2:\n\t"
+		"synco\n\t"
+#ifdef CONFIG_MMU
+		".section	.fixup,\"ax\"\n"
+		"3:\n\t"
+		"mov.l	4f, %0\n\t"
+		"jmp	@%0\n\t"
+		" mov	%3, %0\n\t"
+		".balign	4\n"
+		"4:	.long	2b\n\t"
+		".previous\n"
+		".section	__ex_table,\"a\"\n\t"
+		".long	1b, 3b\n\t"
+		".previous"
+#endif
+		:"+r" (err), "=&r" (*uval)
+		:"r" (uaddr), "i" (-EFAULT), "r" (oldval), "r" (newval)
+		:"t", "memory", "r0");
+	if (err) return err;
+	return 0;
+}
+
+#endif /* __ASM_SH_FUTEX_LLSC_H */

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 */