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ARC: Futex support

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Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2013-01-18 15:12:22 +05:30
parent 547f112571
commit 01b812bcce
1 changed files with 151 additions and 0 deletions
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arch/arc/include/asm/futex.h Normal file
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/*
* 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