/* SPDX-License-Identifier: GPL-2.0-or-later */
/******************************************************************************
*
* Copyright © International Business Machines Corp., 2009
*
* DESCRIPTION
* Glibc independent futex library for testing kernel functionality.
*
* AUTHOR
* Darren Hart <[email protected]>
*
* HISTORY
* 2009-Nov-6: Initial version by Darren Hart <[email protected]>
*
*****************************************************************************/
#ifndef _FUTEXTEST_H
#define _FUTEXTEST_H
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <linux/futex.h>
typedef volatile u_int32_t futex_t;
#define FUTEX_INITIALIZER 0
/* Define the newer op codes if the system header file is not up to date. */
#ifndef FUTEX_WAIT_BITSET
#define FUTEX_WAIT_BITSET 9
#endif
#ifndef FUTEX_WAKE_BITSET
#define FUTEX_WAKE_BITSET 10
#endif
#ifndef FUTEX_WAIT_REQUEUE_PI
#define FUTEX_WAIT_REQUEUE_PI 11
#endif
#ifndef FUTEX_CMP_REQUEUE_PI
#define FUTEX_CMP_REQUEUE_PI 12
#endif
#ifndef FUTEX_WAIT_REQUEUE_PI_PRIVATE
#define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \
FUTEX_PRIVATE_FLAG)
#endif
#ifndef FUTEX_REQUEUE_PI_PRIVATE
#define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \
FUTEX_PRIVATE_FLAG)
#endif
/**
* futex() - SYS_futex syscall wrapper
* @uaddr: address of first futex
* @op: futex op code
* @val: typically expected value of uaddr, but varies by op
* @timeout: typically an absolute struct timespec (except where noted
* otherwise). Overloaded by some ops
* @uaddr2: address of second futex for some ops\
* @val3: varies by op
* @opflags: flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
*
* futex() is used by all the following futex op wrappers. It can also be
* used for misuse and abuse testing. Generally, the specific op wrappers
* should be used instead. It is a macro instead of an static inline function as
* some of the types over overloaded (timeout is used for nr_requeue for
* example).
*
* These argument descriptions are the defaults for all
* like-named arguments in the following wrappers except where noted below.
*/
#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
/**
* futex_wait() - block on uaddr with optional timeout
* @timeout: relative timeout
*/
static inline int
futex_wait(futex_t *uaddr, futex_t val, struct timespec *timeout, int opflags)
{
return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
}
/**
* futex_wake() - wake one or more tasks blocked on uaddr
* @nr_wake: wake up to this many tasks
*/
static inline int
futex_wake(futex_t *uaddr, int nr_wake, int opflags)
{
return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags);
}
/**
* futex_wait_bitset() - block on uaddr with bitset
* @bitset: bitset to be used with futex_wake_bitset
*/
static inline int
futex_wait_bitset(futex_t *uaddr, futex_t val, struct timespec *timeout,
u_int32_t bitset, int opflags)
{
return futex(uaddr, FUTEX_WAIT_BITSET, val, timeout, NULL, bitset,
opflags);
}
/**
* futex_wake_bitset() - wake one or more tasks blocked on uaddr with bitset
* @bitset: bitset to compare with that used in futex_wait_bitset
*/
static inline int
futex_wake_bitset(futex_t *uaddr, int nr_wake, u_int32_t bitset, int opflags)
{
return futex(uaddr, FUTEX_WAKE_BITSET, nr_wake, NULL, NULL, bitset,
opflags);
}
/**
* futex_lock_pi() - block on uaddr as a PI mutex
* @detect: whether (1) or not (0) to perform deadlock detection
*/
static inline int
futex_lock_pi(futex_t *uaddr, struct timespec *timeout, int detect,
int opflags)
{
return futex(uaddr, FUTEX_LOCK_PI, detect, timeout, NULL, 0, opflags);
}
/**
* futex_unlock_pi() - release uaddr as a PI mutex, waking the top waiter
*/
static inline int
futex_unlock_pi(futex_t *uaddr, int opflags)
{
return futex(uaddr, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0, opflags);
}
/**
* futex_wake_op() - FIXME: COME UP WITH A GOOD ONE LINE DESCRIPTION
*/
static inline int
futex_wake_op(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_wake2,
int wake_op, int opflags)
{
return futex(uaddr, FUTEX_WAKE_OP, nr_wake, nr_wake2, uaddr2, wake_op,
opflags);
}
/**
* futex_requeue() - requeue without expected value comparison, deprecated
* @nr_wake: wake up to this many tasks
* @nr_requeue: requeue up to this many tasks
*
* Due to its inherently racy implementation, futex_requeue() is deprecated in
* favor of futex_cmp_requeue().
*/
static inline int
futex_requeue(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_requeue,
int opflags)
{
return futex(uaddr, FUTEX_REQUEUE, nr_wake, nr_requeue, uaddr2, 0,
opflags);
}
/**
* futex_cmp_requeue() - requeue tasks from uaddr to uaddr2
* @nr_wake: wake up to this many tasks
* @nr_requeue: requeue up to this many tasks
*/
static inline int
futex_cmp_requeue(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake,
int nr_requeue, int opflags)
{
return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2,
val, opflags);
}
/**
* futex_wait_requeue_pi() - block on uaddr and prepare to requeue to uaddr2
* @uaddr: non-PI futex source
* @uaddr2: PI futex target
*
* This is the first half of the requeue_pi mechanism. It shall always be
* paired with futex_cmp_requeue_pi().
*/
static inline int
futex_wait_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2,
struct timespec *timeout, int opflags)
{
return futex(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0,
opflags);
}
/**
* futex_cmp_requeue_pi() - requeue tasks from uaddr to uaddr2 (PI aware)
* @uaddr: non-PI futex source
* @uaddr2: PI futex target
* @nr_wake: wake up to this many tasks
* @nr_requeue: requeue up to this many tasks
*/
static inline int
futex_cmp_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake,
int nr_requeue, int opflags)
{
return futex(uaddr, FUTEX_CMP_REQUEUE_PI, nr_wake, nr_requeue, uaddr2,
val, opflags);
}
/**
* futex_cmpxchg() - atomic compare and exchange
* @uaddr: The address of the futex to be modified
* @oldval: The expected value of the futex
* @newval: The new value to try and assign the futex
*
* Implement cmpxchg using gcc atomic builtins.
* http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
*
* Return the old futex value.
*/
static inline u_int32_t
futex_cmpxchg(futex_t *uaddr, u_int32_t oldval, u_int32_t newval)
{
return __sync_val_compare_and_swap(uaddr, oldval, newval);
}
/**
* futex_dec() - atomic decrement of the futex value
* @uaddr: The address of the futex to be modified
*
* Return the new futex value.
*/
static inline u_int32_t
futex_dec(futex_t *uaddr)
{
return __sync_sub_and_fetch(uaddr, 1);
}
/**
* futex_inc() - atomic increment of the futex value
* @uaddr: the address of the futex to be modified
*
* Return the new futex value.
*/
static inline u_int32_t
futex_inc(futex_t *uaddr)
{
return __sync_add_and_fetch(uaddr, 1);
}
/**
* futex_set() - atomic decrement of the futex value
* @uaddr: the address of the futex to be modified
* @newval: New value for the atomic_t
*
* Return the new futex value.
*/
static inline u_int32_t
futex_set(futex_t *uaddr, u_int32_t newval)
{
*uaddr = newval;
return newval;
}
#endif
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