From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Add support for atomic futex operations.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 include/asm-s390/futex.h |   96 +++++++++++++++++++++++++++++++++++--
 1 files changed, 92 insertions(+), 4 deletions(-)

diff -puN include/asm-s390/futex.h~s390-futex-atomic-operations include/asm-s390/futex.h
--- 25/include/asm-s390/futex.h~s390-futex-atomic-operations	Mon Apr 24 16:46:04 2006
+++ 25-akpm/include/asm-s390/futex.h	Mon Apr 24 16:46:04 2006
@@ -1,6 +1,94 @@
-#ifndef _ASM_FUTEX_H
-#define _ASM_FUTEX_H
+#ifndef _ASM_S390_FUTEX_H
+#define _ASM_S390_FUTEX_H
 
-#include <asm-generic/futex.h>
+#ifdef __KERNEL__
 
-#endif
+#include <linux/futex.h>
+#include <asm/errno.h>
+#include <asm/uaccess.h>
+
+#ifndef __s390x__
+#define __futex_atomic_fixup \
+		     ".section __ex_table,\"a\"\n"			\
+		     "   .align 4\n"					\
+		     "   .long  0b,2b,1b,2b\n"				\
+		     ".previous"
+#else /* __s390x__ */
+#define __futex_atomic_fixup \
+		     ".section __ex_table,\"a\"\n"			\
+		     "   .align 8\n"					\
+		     "   .quad  0b,2b,1b,2b\n"				\
+		     ".previous"
+#endif /* __s390x__ */
+
+#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)	\
+	asm volatile("   l   %1,0(%6)\n"				\
+		     "0: " insn						\
+		     "   cs  %1,%2,0(%6)\n"				\
+		     "1: jl  0b\n"					\
+		     "   lhi %0,0\n"					\
+		     "2:\n"						\
+		     __futex_atomic_fixup				\
+		     : "=d" (ret), "=&d" (oldval), "=&d" (newval),	\
+		       "=m" (*(unsigned long __user *) uaddr)		\
+		     : "0" (-EFAULT), "d" (oparg), "a" (uaddr),		\
+		       "m" (*(unsigned long __user *) uaddr) : "cc" );
+
+static inline int futex_atomic_op_inuser (int encoded_op, int __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, newval, ret;
+	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+		oparg = 1 << oparg;
+
+	if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
+		return -EFAULT;
+
+	inc_preempt_count();
+
+	switch (op) {
+	case FUTEX_OP_SET:
+		__futex_atomic_op("lr %2,%5\n",
+				  ret, oldval, newval, uaddr, oparg);
+		break;
+	case FUTEX_OP_ADD:
+		__futex_atomic_op("lr %2,%1\nar %2,%5\n",
+				  ret, oldval, newval, uaddr, oparg);
+		break;
+	case FUTEX_OP_OR:
+		__futex_atomic_op("lr %2,%1\nor %2,%5\n",
+				  ret, oldval, newval, uaddr, oparg);
+		break;
+	case FUTEX_OP_ANDN:
+		__futex_atomic_op("lr %2,%1\nnr %2,%5\n",
+				  ret, oldval, newval, uaddr, oparg);
+		break;
+	case FUTEX_OP_XOR:
+		__futex_atomic_op("lr %2,%1\nxr %2,%5\n",
+				  ret, oldval, newval, uaddr, oparg);
+		break;
+	default:
+		ret = -ENOSYS;
+	}
+
+	dec_preempt_count();
+
+	if (!ret) {
+		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;
+		default: ret = -ENOSYS;
+		}
+	}
+	return ret;
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_S390_FUTEX_H */
_