[PATCH] FRV: Implement futex operations for FRV

The attached patch implements futex operations for the FRV architecture. The
operations are applicable to both MMU and no-MMU modes; though the EFAULT
handling will be a little bit of wasted space on the latter.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 243 insertions, 0 deletions

diff --git a/arch/frv/kernel/Makefile b/arch/frv/kernel/Makefile
index 981c2c7..422f30e 100644
--- a/arch/frv/kernel/Makefile
+++ b/arch/frv/kernel/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_FUJITSU_MB93493)	+= irq-mb93493.o
 obj-$(CONFIG_PM)		+= pm.o cmode.o
 obj-$(CONFIG_MB93093_PDK)	+= pm-mb93093.o
 obj-$(CONFIG_SYSCTL)		+= sysctl.o
+obj-$(CONFIG_FUTEX)		+= futex.o
diff --git a/arch/frv/kernel/futex.c b/arch/frv/kernel/futex.c
new file mode 100644
index 0000000..eae874a
--- /dev/null
+++ b/arch/frv/kernel/futex.c
@@ -0,0 +1,242 @@
+/* futex.c: futex operations
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/futex.h>
+#include <asm/futex.h>
+#include <asm/errno.h>
+#include <asm/uaccess.h>
+
+/*
+ * the various futex operations; MMU fault checking is ignored under no-MMU
+ * conditions
+ */
+static inline int atomic_futex_op_xchg_set(int oparg, int __user *uaddr, int *_oldval)
+{
+	int oldval, ret;
+
+	asm("0:						\n"
+	    "	orcc		gr0,gr0,gr0,icc3	\n"	/* set ICC3.Z */
+	    "	ckeq		icc3,cc7		\n"
+	    "1:	ld.p		%M0,%1			\n"	/* LD.P/ORCR must be atomic */
+	    "	orcr		cc7,cc7,cc3		\n"	/* set CC3 to true */
+	    "2:	cst.p		%3,%M0		,cc3,#1	\n"
+	    "	corcc		gr29,gr29,gr0	,cc3,#1	\n"	/* clear ICC3.Z if store happens */
+	    "	beq		icc3,#0,0b		\n"
+	    "	setlos		0,%2			\n"
+	    "3:						\n"
+	    ".subsection 2				\n"
+	    "4:	setlos		%5,%2			\n"
+	    "	bra		3b			\n"
+	    ".previous					\n"
+	    ".section __ex_table,\"a\"			\n"
+	    "	.balign		8			\n"
+	    "	.long		1b,4b			\n"
+	    "	.long		2b,4b			\n"
+	    ".previous"
+	    : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
+	    : "3"(oparg), "i"(-EFAULT)
+	    : "memory", "cc7", "cc3", "icc3"
+	    );
+
+	*_oldval = oldval;
+	return ret;
+}
+
+static inline int atomic_futex_op_xchg_add(int oparg, int __user *uaddr, int *_oldval)
+{
+	int oldval, ret;
+
+	asm("0:						\n"
+	    "	orcc		gr0,gr0,gr0,icc3	\n"	/* set ICC3.Z */
+	    "	ckeq		icc3,cc7		\n"
+	    "1:	ld.p		%M0,%1			\n"	/* LD.P/ORCR must be atomic */
+	    "	orcr		cc7,cc7,cc3		\n"	/* set CC3 to true */
+	    "	add		%1,%3,%3		\n"
+	    "2:	cst.p		%3,%M0		,cc3,#1	\n"
+	    "	corcc		gr29,gr29,gr0	,cc3,#1	\n"	/* clear ICC3.Z if store happens */
+	    "	beq		icc3,#0,0b		\n"
+	    "	setlos		0,%2			\n"
+	    "3:						\n"
+	    ".subsection 2				\n"
+	    "4:	setlos		%5,%2			\n"
+	    "	bra		3b			\n"
+	    ".previous					\n"
+	    ".section __ex_table,\"a\"			\n"
+	    "	.balign		8			\n"
+	    "	.long		1b,4b			\n"
+	    "	.long		2b,4b			\n"
+	    ".previous"
+	    : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
+	    : "3"(oparg), "i"(-EFAULT)
+	    : "memory", "cc7", "cc3", "icc3"
+	    );
+
+	*_oldval = oldval;
+	return ret;
+}
+
+static inline int atomic_futex_op_xchg_or(int oparg, int __user *uaddr, int *_oldval)
+{
+	int oldval, ret;
+
+	asm("0:						\n"
+	    "	orcc		gr0,gr0,gr0,icc3	\n"	/* set ICC3.Z */
+	    "	ckeq		icc3,cc7		\n"
+	    "1:	ld.p		%M0,%1			\n"	/* LD.P/ORCR must be atomic */
+	    "	orcr		cc7,cc7,cc3		\n"	/* set CC3 to true */
+	    "	or		%1,%3,%3		\n"
+	    "2:	cst.p		%3,%M0		,cc3,#1	\n"
+	    "	corcc		gr29,gr29,gr0	,cc3,#1	\n"	/* clear ICC3.Z if store happens */
+	    "	beq		icc3,#0,0b		\n"
+	    "	setlos		0,%2			\n"
+	    "3:						\n"
+	    ".subsection 2				\n"
+	    "4:	setlos		%5,%2			\n"
+	    "	bra		3b			\n"
+	    ".previous					\n"
+	    ".section __ex_table,\"a\"			\n"
+	    "	.balign		8			\n"
+	    "	.long		1b,4b			\n"
+	    "	.long		2b,4b			\n"
+	    ".previous"
+	    : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
+	    : "3"(oparg), "i"(-EFAULT)
+	    : "memory", "cc7", "cc3", "icc3"
+	    );
+
+	*_oldval = oldval;
+	return ret;
+}
+
+static inline int atomic_futex_op_xchg_and(int oparg, int __user *uaddr, int *_oldval)
+{
+	int oldval, ret;
+
+	asm("0:						\n"
+	    "	orcc		gr0,gr0,gr0,icc3	\n"	/* set ICC3.Z */
+	    "	ckeq		icc3,cc7		\n"
+	    "1:	ld.p		%M0,%1			\n"	/* LD.P/ORCR must be atomic */
+	    "	orcr		cc7,cc7,cc3		\n"	/* set CC3 to true */
+	    "	and		%1,%3,%3		\n"
+	    "2:	cst.p		%3,%M0		,cc3,#1	\n"
+	    "	corcc		gr29,gr29,gr0	,cc3,#1	\n"	/* clear ICC3.Z if store happens */
+	    "	beq		icc3,#0,0b		\n"
+	    "	setlos		0,%2			\n"
+	    "3:						\n"
+	    ".subsection 2				\n"
+	    "4:	setlos		%5,%2			\n"
+	    "	bra		3b			\n"
+	    ".previous					\n"
+	    ".section __ex_table,\"a\"			\n"
+	    "	.balign		8			\n"
+	    "	.long		1b,4b			\n"
+	    "	.long		2b,4b			\n"
+	    ".previous"
+	    : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
+	    : "3"(oparg), "i"(-EFAULT)
+	    : "memory", "cc7", "cc3", "icc3"
+	    );
+
+	*_oldval = oldval;
+	return ret;
+}
+
+static inline int atomic_futex_op_xchg_xor(int oparg, int __user *uaddr, int *_oldval)
+{
+	int oldval, ret;
+
+	asm("0:						\n"
+	    "	orcc		gr0,gr0,gr0,icc3	\n"	/* set ICC3.Z */
+	    "	ckeq		icc3,cc7		\n"
+	    "1:	ld.p		%M0,%1			\n"	/* LD.P/ORCR must be atomic */
+	    "	orcr		cc7,cc7,cc3		\n"	/* set CC3 to true */
+	    "	xor		%1,%3,%3		\n"
+	    "2:	cst.p		%3,%M0		,cc3,#1	\n"
+	    "	corcc		gr29,gr29,gr0	,cc3,#1	\n"	/* clear ICC3.Z if store happens */
+	    "	beq		icc3,#0,0b		\n"
+	    "	setlos		0,%2			\n"
+	    "3:						\n"
+	    ".subsection 2				\n"
+	    "4:	setlos		%5,%2			\n"
+	    "	bra		3b			\n"
+	    ".previous					\n"
+	    ".section __ex_table,\"a\"			\n"
+	    "	.balign		8			\n"
+	    "	.long		1b,4b			\n"
+	    "	.long		2b,4b			\n"
+	    ".previous"
+	    : "+U"(*uaddr), "=&r"(oldval), "=&r"(ret), "=r"(oparg)
+	    : "3"(oparg), "i"(-EFAULT)
+	    : "memory", "cc7", "cc3", "icc3"
+	    );
+
+	*_oldval = oldval;
+	return ret;
+}
+
+/*****************************************************************************/
+/*
+ * do the futex operations
+ */
+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, 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:
+		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;
+	}
+
+	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; break;
+		}
+	}
+
+	return ret;
+
+} /* end futex_atomic_op_inuser() */