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152 lines
3.5 KiB
C
152 lines
3.5 KiB
C
/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Vineetg: August 2010: From Android kernel work
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*/
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#ifndef _ASM_FUTEX_H
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#define _ASM_FUTEX_H
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#include <linux/futex.h>
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#include <linux/preempt.h>
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#include <linux/uaccess.h>
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#include <asm/errno.h>
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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
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\
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__asm__ __volatile__( \
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"1: ld %1, [%2] \n" \
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insn "\n" \
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"2: st %0, [%2] \n" \
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" mov %0, 0 \n" \
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"3: \n" \
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" .section .fixup,\"ax\" \n" \
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" .align 4 \n" \
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"4: mov %0, %4 \n" \
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" b 3b \n" \
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" .previous \n" \
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" .section __ex_table,\"a\" \n" \
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" .align 4 \n" \
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" .word 1b, 4b \n" \
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" .word 2b, 4b \n" \
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" .previous \n" \
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\
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: "=&r" (ret), "=&r" (oldval) \
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: "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
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: "cc", "memory")
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static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
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{
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int op = (encoded_op >> 28) & 7;
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int cmp = (encoded_op >> 24) & 15;
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int oparg = (encoded_op << 8) >> 20;
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int cmparg = (encoded_op << 20) >> 20;
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int oldval = 0, ret;
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if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
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oparg = 1 << oparg;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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pagefault_disable(); /* implies preempt_disable() */
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switch (op) {
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case FUTEX_OP_SET:
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__futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ADD:
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__futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_OR:
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__futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ANDN:
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__futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_XOR:
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__futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
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break;
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default:
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ret = -ENOSYS;
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}
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pagefault_enable(); /* subsumes preempt_enable() */
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if (!ret) {
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switch (cmp) {
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case FUTEX_OP_CMP_EQ:
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ret = (oldval == cmparg);
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break;
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case FUTEX_OP_CMP_NE:
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ret = (oldval != cmparg);
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break;
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case FUTEX_OP_CMP_LT:
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ret = (oldval < cmparg);
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break;
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case FUTEX_OP_CMP_GE:
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ret = (oldval >= cmparg);
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break;
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case FUTEX_OP_CMP_LE:
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ret = (oldval <= cmparg);
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break;
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case FUTEX_OP_CMP_GT:
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ret = (oldval > cmparg);
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break;
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default:
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ret = -ENOSYS;
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}
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}
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return ret;
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}
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/* Compare-xchg with preemption disabled.
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* Notes:
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* -Best-Effort: Exchg happens only if compare succeeds.
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* If compare fails, returns; leaving retry/looping to upper layers
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* -successful cmp-xchg: return orig value in @addr (same as cmp val)
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* -Compare fails: return orig value in @addr
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* -user access r/w fails: return -EFAULT
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*/
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static inline int
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futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
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u32 newval)
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{
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u32 val;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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pagefault_disable(); /* implies preempt_disable() */
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/* TBD : can use llock/scond */
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__asm__ __volatile__(
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"1: ld %0, [%3] \n"
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" brne %0, %1, 3f \n"
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"2: st %2, [%3] \n"
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"3: \n"
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" .section .fixup,\"ax\" \n"
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"4: mov %0, %4 \n"
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" b 3b \n"
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" .previous \n"
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" .section __ex_table,\"a\" \n"
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" .align 4 \n"
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" .word 1b, 4b \n"
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" .word 2b, 4b \n"
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" .previous\n"
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: "=&r"(val)
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: "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
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: "cc", "memory");
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pagefault_enable(); /* subsumes preempt_enable() */
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*uval = val;
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return val;
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}
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#endif
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