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Subject[RFC Patch v1 34/55] ARC: futex
Date
From: Vineet Gupta <vgupta@synopsys.com>

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/include/asm/futex.h | 151 ++++++++++++++++++++++++++++++++++++++++++
1 files changed, 151 insertions(+), 0 deletions(-)
create mode 100644 arch/arc/include/asm/futex.h

diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
new file mode 100644
index 0000000..4dc64dd
--- /dev/null
+++ b/arch/arc/include/asm/futex.h
@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Vineetg: August 2010: From Android kernel work
+ */
+
+#ifndef _ASM_FUTEX_H
+#define _ASM_FUTEX_H
+
+#include <linux/futex.h>
+#include <linux/preempt.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
+ \
+ __asm__ __volatile__( \
+ "1: ld %1, [%2] \n" \
+ insn "\n" \
+ "2: st %0, [%2] \n" \
+ " mov %0, 0 \n" \
+ "3: \n" \
+ " .section .fixup,\"ax\" \n" \
+ " .align 4 \n" \
+ "4: mov %0, %4 \n" \
+ " b 3b \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " .align 4 \n" \
+ " .word 1b, 4b \n" \
+ " .word 2b, 4b \n" \
+ " .previous \n" \
+ \
+ : "=&r" (ret), "=&r" (oldval) \
+ : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
+ : "cc", "memory")
+
+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;
+
+ if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+ oparg = 1 << oparg;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ return -EFAULT;
+
+ pagefault_disable(); /* implies preempt_disable() */
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ pagefault_enable(); /* subsumes preempt_enable() */
+
+ 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;
+}
+
+/* Compare-xchg with preemption disabled.
+ * Notes:
+ * -Best-Effort: Exchg happens only if compare succeeds.
+ * If compare fails, returns; leaving retry/looping to upper layers
+ * -successful cmp-xchg: return orig value in @addr (same as cmp val)
+ * -Compare fails: return orig value in @addr
+ * -user access r/w fails: return -EFAULT
+ */
+static inline int
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
+ u32 newval)
+{
+ u32 val;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ return -EFAULT;
+
+ pagefault_disable(); /* implies preempt_disable() */
+
+ /* TBD : can use llock/scond */
+ __asm__ __volatile__(
+ "1: ld %0, [%3] \n"
+ " brne %0, %1, 3f \n"
+ "2: st %2, [%3] \n"
+ "3: \n"
+ " .section .fixup,\"ax\" \n"
+ "4: mov %0, %4 \n"
+ " b 3b \n"
+ " .previous \n"
+ " .section __ex_table,\"a\" \n"
+ " .align 4 \n"
+ " .word 1b, 4b \n"
+ " .word 2b, 4b \n"
+ " .previous\n"
+ : "=&r"(val)
+ : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
+ : "cc", "memory");
+
+ pagefault_enable(); /* subsumes preempt_enable() */
+
+ *uval = val;
+ return val;
+}
+
+#endif
--
1.7.4.1


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