futex.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Glibc independent futex library for testing kernel functionality.
  4 * Shamelessly stolen from Darren Hart <dvhltc@us.ibm.com>
  5 *    http://git.kernel.org/cgit/linux/kernel/git/dvhart/futextest.git/
  6 */
  7
  8#ifndef _FUTEX_H
  9#define _FUTEX_H
 10
 11#include <stdbool.h>
 12#include <unistd.h>
 13#include <sys/syscall.h>
 14#include <sys/types.h>
 15#include <linux/futex.h>
 16
 17struct bench_futex_parameters {
 18	bool silent;
 19	bool fshared;
 20	bool mlockall;
 21	bool multi; /* lock-pi */
 22	bool pi; /* requeue-pi */
 23	bool broadcast; /* requeue */
 24	unsigned int runtime; /* seconds*/
 25	unsigned int nthreads;
 26	unsigned int nfutexes;
 27	unsigned int nwakes;
 28	unsigned int nrequeue;
 29	int nbuckets;
 30};
 31
 32/**
 33 * futex_syscall() - SYS_futex syscall wrapper
 34 * @uaddr:	address of first futex
 35 * @op:		futex op code
 36 * @val:	typically expected value of uaddr, but varies by op
 37 * @timeout:	typically an absolute struct timespec (except where noted
 38 *		otherwise). Overloaded by some ops
 39 * @uaddr2:	address of second futex for some ops
 40 * @val3:	varies by op
 41 * @opflags:	flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
 42 *
 43 * futex_syscall() is used by all the following futex op wrappers. It can also be
 44 * used for misuse and abuse testing. Generally, the specific op wrappers
 45 * should be used instead.
 46 *
 47 * These argument descriptions are the defaults for all
 48 * like-named arguments in the following wrappers except where noted below.
 49 */
 50static inline int
 51futex_syscall(volatile u_int32_t *uaddr, int op, u_int32_t val, struct timespec *timeout,
 52	      volatile u_int32_t *uaddr2, int val3, int opflags)
 53{
 54	return syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3);
 55}
 56
 57static inline int
 58futex_syscall_nr_requeue(volatile u_int32_t *uaddr, int op, u_int32_t val, int nr_requeue,
 59			 volatile u_int32_t *uaddr2, int val3, int opflags)
 60{
 61	return syscall(SYS_futex, uaddr, op | opflags, val, nr_requeue, uaddr2, val3);
 62}
 63
 64/**
 65 * futex_wait() - block on uaddr with optional timeout
 66 * @timeout:	relative timeout
 67 */
 68static inline int
 69futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflags)
 70{
 71	return futex_syscall(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
 72}
 73
 74/**
 75 * futex_wake() - wake one or more tasks blocked on uaddr
 76 * @nr_wake:	wake up to this many tasks
 77 */
 78static inline int
 79futex_wake(u_int32_t *uaddr, int nr_wake, int opflags)
 80{
 81	return futex_syscall(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags);
 82}
 83
 84/**
 85 * futex_lock_pi() - block on uaddr as a PI mutex
 86 */
 87static inline int
 88futex_lock_pi(u_int32_t *uaddr, struct timespec *timeout, int opflags)
 89{
 90	return futex_syscall(uaddr, FUTEX_LOCK_PI, 0, timeout, NULL, 0, opflags);
 91}
 92
 93/**
 94 * futex_unlock_pi() - release uaddr as a PI mutex, waking the top waiter
 95 */
 96static inline int
 97futex_unlock_pi(u_int32_t *uaddr, int opflags)
 98{
 99	return futex_syscall(uaddr, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0, opflags);
100}
101
102/**
103* futex_cmp_requeue() - requeue tasks from uaddr to uaddr2
104* @nr_wake:        wake up to this many tasks
105* @nr_requeue:     requeue up to this many tasks
106*/
107static inline int
108futex_cmp_requeue(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, int nr_wake,
109		 int nr_requeue, int opflags)
110{
111	return futex_syscall_nr_requeue(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2,
112					val, opflags);
113}
114
115/**
116 * futex_wait_requeue_pi() - block on uaddr and prepare to requeue to uaddr2
117 * @uaddr:	non-PI futex source
118 * @uaddr2:	PI futex target
119 *
120 * This is the first half of the requeue_pi mechanism. It shall always be
121 * paired with futex_cmp_requeue_pi().
122 */
123static inline int
124futex_wait_requeue_pi(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2,
125		      struct timespec *timeout, int opflags)
126{
127	return futex_syscall(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0,
128			     opflags);
129}
130
131/**
132 * futex_cmp_requeue_pi() - requeue tasks from uaddr to uaddr2
133 * @uaddr:	non-PI futex source
134 * @uaddr2:	PI futex target
135 * @nr_requeue:	requeue up to this many tasks
136 *
137 * This is the second half of the requeue_pi mechanism. It shall always be
138 * paired with futex_wait_requeue_pi(). The first waker is always awoken.
139 */
140static inline int
141futex_cmp_requeue_pi(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2,
142		     int nr_requeue, int opflags)
143{
144	return futex_syscall_nr_requeue(uaddr, FUTEX_CMP_REQUEUE_PI, 1, nr_requeue, uaddr2,
145					val, opflags);
146}
147
148void futex_set_nbuckets_param(struct bench_futex_parameters *params);
149void futex_print_nbuckets(struct bench_futex_parameters *params);
150
151#endif /* _FUTEX_H */