| 1 |
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| 2 | #ifndef _ASM_GENERIC_FUTEX_H
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| 3 | #define _ASM_GENERIC_FUTEX_H
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| 4 |
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| 5 | #include <linux/futex.h>
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| 6 | #include <linux/uaccess.h>
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| 7 | #include <asm/errno.h>
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| 8 |
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| 9 | #ifndef futex_atomic_cmpxchg_inatomic
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| 10 | #ifndef CONFIG_SMP
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| 11 | |
| 12 | * The following implementation only for uniprocessor machines.
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| 13 | * It relies on preempt_disable() ensuring mutual exclusion.
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| 14 | *
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| 15 |
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| 16 | #define futex_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval) \
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| 17 | futex_atomic_cmpxchg_inatomic_local(uval, uaddr, oldval, newval)
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| 18 | #define arch_futex_atomic_op_inuser(op, oparg, oval, uaddr) \
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| 19 | futex_atomic_op_inuser_local(op, oparg, oval, uaddr)
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| 20 | #endif
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| 21 | #endif
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| 22 |
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| 23 | |
| 24 | * futex_atomic_op_inuser_local() - Atomic arithmetic operation with constant
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| 25 | * argument and comparison of the previous
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| 26 | * futex value with another constant.
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| 27 | *
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| 28 | * @op: operation to execute
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| 29 | * @oparg: argument of the operation
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| 30 | * @oval: previous value at @uaddr on successful return
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| 31 | * @uaddr: pointer to user space address
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| 32 | *
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| 33 | * Return:
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| 34 | * 0 - On success
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| 35 | * -EFAULT - User access resulted in a page fault
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| 36 | * -EAGAIN - Atomic operation was unable to complete due to contention
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| 37 | * -ENOSYS - Operation not supported
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| 38 |
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| 39 | static inline int
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| 40 | futex_atomic_op_inuser_local(int op, u32 oparg, int *oval, u32 __user *uaddr)
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| 41 | {
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| 42 | int oldval, ret;
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| 43 | u32 tmp;
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| 44 |
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| 45 | preempt_disable();
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| 46 |
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| 47 | ret = -EFAULT;
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| 48 | if (unlikely(get_user(oldval, uaddr) != 0))
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| 49 | goto out_pagefault_enable;
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| 50 |
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| 51 | ret = 0;
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| 52 | tmp = oldval;
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| 53 |
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| 54 | switch (op) {
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| 55 | case FUTEX_OP_SET:
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| 56 | tmp = oparg;
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| 57 | break;
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| 58 | case FUTEX_OP_ADD:
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| 59 | tmp += oparg;
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| 60 | break;
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| 61 | case FUTEX_OP_OR:
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| 62 | tmp |= oparg;
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| 63 | break;
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| 64 | case FUTEX_OP_ANDN:
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| 65 | tmp &= ~oparg;
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| 66 | break;
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| 67 | case FUTEX_OP_XOR:
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| 68 | tmp ^= oparg;
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| 69 | break;
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| 70 | default:
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| 71 | ret = -ENOSYS;
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| 72 | }
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| 73 |
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| 74 | if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
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| 75 | ret = -EFAULT;
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| 76 |
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| 77 | out_pagefault_enable:
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| 78 | preempt_enable();
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| 79 |
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| 80 | if (ret == 0)
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| 81 | *oval = oldval;
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| 82 |
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| 83 | return ret;
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| 84 | }
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| 85 |
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| 86 | |
| 87 | * futex_atomic_cmpxchg_inatomic_local() - Compare and exchange the content of the
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| 88 | * uaddr with newval if the current value is
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| 89 | * oldval.
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| 90 | * @uval: pointer to store content of @uaddr
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| 91 | * @uaddr: pointer to user space address
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| 92 | * @oldval: old value
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| 93 | * @newval: new value to store to @uaddr
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| 94 | *
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| 95 | * Return:
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| 96 | * 0 - On success
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| 97 | * -EFAULT - User access resulted in a page fault
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| 98 | * -EAGAIN - Atomic operation was unable to complete due to contention
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| 99 |
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| 100 | static inline int
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| 101 | futex_atomic_cmpxchg_inatomic_local(u32 *uval, u32 __user *uaddr,
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| 102 | u32 oldval, u32 newval)
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| 103 | {
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| 104 | u32 val;
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| 105 |
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| 106 | preempt_disable();
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| 107 | if (unlikely(get_user(val, uaddr) != 0)) {
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| 108 | preempt_enable();
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| 109 | return -EFAULT;
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| 110 | }
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| 111 |
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| 112 | if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) {
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| 113 | preempt_enable();
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| 114 | return -EFAULT;
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| 115 | }
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| 116 |
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| 117 | *uval = val;
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| 118 | preempt_enable();
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| 119 |
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| 120 | return 0;
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| 121 | }
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| 122 |
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| 123 | #endif
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