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130 lines
2.6 KiB
130 lines
2.6 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _ASM_GENERIC_FUTEX_H |
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#define _ASM_GENERIC_FUTEX_H |
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#include <linux/futex.h> |
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#include <linux/uaccess.h> |
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#include <asm/errno.h> |
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#ifndef CONFIG_SMP |
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/* |
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* The following implementation only for uniprocessor machines. |
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* It relies on preempt_disable() ensuring mutual exclusion. |
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* |
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*/ |
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/** |
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* arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant |
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* argument and comparison of the previous |
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* futex value with another constant. |
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* |
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* @encoded_op: encoded operation to execute |
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* @uaddr: pointer to user space address |
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* |
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* Return: |
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* 0 - On success |
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* -EFAULT - User access resulted in a page fault |
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* -EAGAIN - Atomic operation was unable to complete due to contention |
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* -ENOSYS - Operation not supported |
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*/ |
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static inline int |
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arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) |
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{ |
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int oldval, ret; |
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u32 tmp; |
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preempt_disable(); |
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ret = -EFAULT; |
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if (unlikely(get_user(oldval, uaddr) != 0)) |
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goto out_pagefault_enable; |
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ret = 0; |
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tmp = oldval; |
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switch (op) { |
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case FUTEX_OP_SET: |
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tmp = oparg; |
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break; |
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case FUTEX_OP_ADD: |
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tmp += oparg; |
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break; |
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case FUTEX_OP_OR: |
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tmp |= oparg; |
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break; |
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case FUTEX_OP_ANDN: |
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tmp &= ~oparg; |
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break; |
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case FUTEX_OP_XOR: |
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tmp ^= 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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if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) |
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ret = -EFAULT; |
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out_pagefault_enable: |
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preempt_enable(); |
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if (ret == 0) |
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*oval = oldval; |
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return ret; |
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} |
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/** |
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* futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the |
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* uaddr with newval if the current value is |
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* oldval. |
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* @uval: pointer to store content of @uaddr |
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* @uaddr: pointer to user space address |
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* @oldval: old value |
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* @newval: new value to store to @uaddr |
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* |
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* Return: |
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* 0 - On success |
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* -EFAULT - User access resulted in a page fault |
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* -EAGAIN - Atomic operation was unable to complete due to contention |
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* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG) |
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*/ |
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static inline int |
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futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, |
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u32 oldval, u32 newval) |
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{ |
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u32 val; |
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preempt_disable(); |
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if (unlikely(get_user(val, uaddr) != 0)) { |
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preempt_enable(); |
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return -EFAULT; |
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} |
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if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { |
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preempt_enable(); |
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return -EFAULT; |
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} |
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*uval = val; |
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preempt_enable(); |
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return 0; |
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} |
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#else |
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static inline int |
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arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) |
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{ |
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return -ENOSYS; |
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} |
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static inline int |
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futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, |
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u32 oldval, u32 newval) |
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{ |
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return -ENOSYS; |
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} |
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#endif /* CONFIG_SMP */ |
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#endif
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