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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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2.7 kB · 123 lines
C
at master
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124/* SPDX-License-Identifier: GPL-2.0 */#ifndef _ASM_GENERIC_FUTEX_H#define _ASM_GENERIC_FUTEX_H
#include <linux/futex.h>#include <linux/uaccess.h>#include <asm/errno.h>
#ifndef futex_atomic_cmpxchg_inatomic#ifndef CONFIG_SMP/* * The following implementation only for uniprocessor machines. * It relies on preempt_disable() ensuring mutual exclusion. * */#define futex_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval) \ futex_atomic_cmpxchg_inatomic_local(uval, uaddr, oldval, newval)#define arch_futex_atomic_op_inuser(op, oparg, oval, uaddr) \ futex_atomic_op_inuser_local(op, oparg, oval, uaddr)#endif /* CONFIG_SMP */#endif
/** * futex_atomic_op_inuser_local() - Atomic arithmetic operation with constant * argument and comparison of the previous * futex value with another constant. * * @op: operation to execute * @oparg: argument of the operation * @oval: previous value at @uaddr on successful return * @uaddr: pointer to user space address * * Return: * 0 - On success * -EFAULT - User access resulted in a page fault * -EAGAIN - Atomic operation was unable to complete due to contention * -ENOSYS - Operation not supported */static inline intfutex_atomic_op_inuser_local(int op, u32 oparg, int *oval, u32 __user *uaddr){ int oldval, ret; u32 tmp;
preempt_disable();
ret = -EFAULT; if (unlikely(get_user(oldval, uaddr) != 0)) goto out_pagefault_enable;
ret = 0; tmp = oldval;
switch (op) { case FUTEX_OP_SET: tmp = oparg; break; case FUTEX_OP_ADD: tmp += oparg; break; case FUTEX_OP_OR: tmp |= oparg; break; case FUTEX_OP_ANDN: tmp &= ~oparg; break; case FUTEX_OP_XOR: tmp ^= oparg; break; default: ret = -ENOSYS; }
if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) ret = -EFAULT;
out_pagefault_enable: preempt_enable();
if (ret == 0) *oval = oldval;
return ret;}
/** * futex_atomic_cmpxchg_inatomic_local() - Compare and exchange the content of the * uaddr with newval if the current value is * oldval. * @uval: pointer to store content of @uaddr * @uaddr: pointer to user space address * @oldval: old value * @newval: new value to store to @uaddr * * Return: * 0 - On success * -EFAULT - User access resulted in a page fault * -EAGAIN - Atomic operation was unable to complete due to contention */static inline intfutex_atomic_cmpxchg_inatomic_local(u32 *uval, u32 __user *uaddr, u32 oldval, u32 newval){ u32 val;
preempt_disable(); if (unlikely(get_user(val, uaddr) != 0)) { preempt_enable(); return -EFAULT; }
if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { preempt_enable(); return -EFAULT; }
*uval = val; preempt_enable();
return 0;}
#endif