futextest.h

  1/* SPDX-License-Identifier: GPL-2.0-or-later */
  2/******************************************************************************
  3 *
  4 *   Copyright © International Business Machines  Corp., 2009
  5 *
  6 * DESCRIPTION
  7 *      Glibc independent futex library for testing kernel functionality.
  8 *
  9 * AUTHOR
 10 *      Darren Hart <dvhart@linux.intel.com>
 11 *
 12 * HISTORY
 13 *      2009-Nov-6: Initial version by Darren Hart <dvhart@linux.intel.com>
 14 *
 15 *****************************************************************************/
 16
 17#ifndef _FUTEXTEST_H
 18#define _FUTEXTEST_H
 19
 20#include <unistd.h>
 21#include <sys/syscall.h>
 22#include <sys/types.h>
 23#include <linux/futex.h>
 24
 25typedef volatile u_int32_t futex_t;
 26#define FUTEX_INITIALIZER 0
 27
 28/* Define the newer op codes if the system header file is not up to date. */
 29#ifndef FUTEX_WAIT_BITSET
 30#define FUTEX_WAIT_BITSET		9
 31#endif
 32#ifndef FUTEX_WAKE_BITSET
 33#define FUTEX_WAKE_BITSET		10
 34#endif
 35#ifndef FUTEX_WAIT_REQUEUE_PI
 36#define FUTEX_WAIT_REQUEUE_PI		11
 37#endif
 38#ifndef FUTEX_CMP_REQUEUE_PI
 39#define FUTEX_CMP_REQUEUE_PI		12
 40#endif
 41#ifndef FUTEX_WAIT_REQUEUE_PI_PRIVATE
 42#define FUTEX_WAIT_REQUEUE_PI_PRIVATE	(FUTEX_WAIT_REQUEUE_PI | \
 43					 FUTEX_PRIVATE_FLAG)
 44#endif
 45#ifndef FUTEX_REQUEUE_PI_PRIVATE
 46#define FUTEX_CMP_REQUEUE_PI_PRIVATE	(FUTEX_CMP_REQUEUE_PI | \
 47					 FUTEX_PRIVATE_FLAG)
 48#endif
 49
 50/*
 51 * SYS_futex is expected from system C library, in glibc some 32-bit
 52 * architectures (e.g. RV32) are using 64-bit time_t, therefore it doesn't have
 53 * SYS_futex defined but just SYS_futex_time64. Define SYS_futex as
 54 * SYS_futex_time64 in this situation to ensure the compilation and the
 55 * compatibility.
 56 */
 57#if !defined(SYS_futex) && defined(SYS_futex_time64)
 58#define SYS_futex SYS_futex_time64
 59#endif
 60
 61/*
 62 * On 32bit systems if we use "-D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64" or if
 63 * we are using a newer compiler then the size of the timestamps will be 64bit,
 64 * however, the SYS_futex will still point to the 32bit futex system call.
 65 */
 66#if __SIZEOF_POINTER__ == 4 && defined(SYS_futex_time64) && \
 67	defined(_TIME_BITS) && _TIME_BITS == 64
 68# undef SYS_futex
 69# define SYS_futex SYS_futex_time64
 70#endif
 71
 72/**
 73 * futex() - SYS_futex syscall wrapper
 74 * @uaddr:	address of first futex
 75 * @op:		futex op code
 76 * @val:	typically expected value of uaddr, but varies by op
 77 * @timeout:	typically an absolute struct timespec (except where noted
 78 *              otherwise). Overloaded by some ops
 79 * @uaddr2:	address of second futex for some ops\
 80 * @val3:	varies by op
 81 * @opflags:	flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG
 82 *
 83 * futex() is used by all the following futex op wrappers. It can also be
 84 * used for misuse and abuse testing. Generally, the specific op wrappers
 85 * should be used instead. It is a macro instead of an static inline function as
 86 * some of the types over overloaded (timeout is used for nr_requeue for
 87 * example).
 88 *
 89 * These argument descriptions are the defaults for all
 90 * like-named arguments in the following wrappers except where noted below.
 91 */
 92#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
 93	syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
 94
 95/**
 96 * futex_wait() - block on uaddr with optional timeout
 97 * @timeout:	relative timeout
 98 */
 99static inline int
100futex_wait(futex_t *uaddr, futex_t val, struct timespec *timeout, int opflags)
101{
102	return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
103}
104
105/**
106 * futex_wake() - wake one or more tasks blocked on uaddr
107 * @nr_wake:	wake up to this many tasks
108 */
109static inline int
110futex_wake(futex_t *uaddr, int nr_wake, int opflags)
111{
112	return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags);
113}
114
115/**
116 * futex_wait_bitset() - block on uaddr with bitset
117 * @bitset:	bitset to be used with futex_wake_bitset
118 */
119static inline int
120futex_wait_bitset(futex_t *uaddr, futex_t val, struct timespec *timeout,
121		  u_int32_t bitset, int opflags)
122{
123	return futex(uaddr, FUTEX_WAIT_BITSET, val, timeout, NULL, bitset,
124		     opflags);
125}
126
127/**
128 * futex_wake_bitset() - wake one or more tasks blocked on uaddr with bitset
129 * @bitset:	bitset to compare with that used in futex_wait_bitset
130 */
131static inline int
132futex_wake_bitset(futex_t *uaddr, int nr_wake, u_int32_t bitset, int opflags)
133{
134	return futex(uaddr, FUTEX_WAKE_BITSET, nr_wake, NULL, NULL, bitset,
135		     opflags);
136}
137
138/**
139 * futex_lock_pi() - block on uaddr as a PI mutex
140 * @detect:	whether (1) or not (0) to perform deadlock detection
141 */
142static inline int
143futex_lock_pi(futex_t *uaddr, struct timespec *timeout, int detect,
144	      int opflags)
145{
146	return futex(uaddr, FUTEX_LOCK_PI, detect, timeout, NULL, 0, opflags);
147}
148
149/**
150 * futex_unlock_pi() - release uaddr as a PI mutex, waking the top waiter
151 */
152static inline int
153futex_unlock_pi(futex_t *uaddr, int opflags)
154{
155	return futex(uaddr, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0, opflags);
156}
157
158/**
159 * futex_wake_op() - FIXME: COME UP WITH A GOOD ONE LINE DESCRIPTION
160 */
161static inline int
162futex_wake_op(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_wake2,
163	      int wake_op, int opflags)
164{
165	return futex(uaddr, FUTEX_WAKE_OP, nr_wake, nr_wake2, uaddr2, wake_op,
166		     opflags);
167}
168
169/**
170 * futex_requeue() - requeue without expected value comparison, deprecated
171 * @nr_wake:	wake up to this many tasks
172 * @nr_requeue:	requeue up to this many tasks
173 *
174 * Due to its inherently racy implementation, futex_requeue() is deprecated in
175 * favor of futex_cmp_requeue().
176 */
177static inline int
178futex_requeue(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_requeue,
179	      int opflags)
180{
181	return futex(uaddr, FUTEX_REQUEUE, nr_wake, nr_requeue, uaddr2, 0,
182		     opflags);
183}
184
185/**
186 * futex_cmp_requeue() - requeue tasks from uaddr to uaddr2
187 * @nr_wake:	wake up to this many tasks
188 * @nr_requeue:	requeue up to this many tasks
189 */
190static inline int
191futex_cmp_requeue(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake,
192		  int nr_requeue, int opflags)
193{
194	return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2,
195		     val, opflags);
196}
197
198/**
199 * futex_wait_requeue_pi() - block on uaddr and prepare to requeue to uaddr2
200 * @uaddr:	non-PI futex source
201 * @uaddr2:	PI futex target
202 *
203 * This is the first half of the requeue_pi mechanism. It shall always be
204 * paired with futex_cmp_requeue_pi().
205 */
206static inline int
207futex_wait_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2,
208		      struct timespec *timeout, int opflags)
209{
210	return futex(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0,
211		     opflags);
212}
213
214/**
215 * futex_cmp_requeue_pi() - requeue tasks from uaddr to uaddr2 (PI aware)
216 * @uaddr:	non-PI futex source
217 * @uaddr2:	PI futex target
218 * @nr_wake:	wake up to this many tasks
219 * @nr_requeue:	requeue up to this many tasks
220 */
221static inline int
222futex_cmp_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake,
223		     int nr_requeue, int opflags)
224{
225	return futex(uaddr, FUTEX_CMP_REQUEUE_PI, nr_wake, nr_requeue, uaddr2,
226		     val, opflags);
227}
228
229/**
230 * futex_cmpxchg() - atomic compare and exchange
231 * @uaddr:	The address of the futex to be modified
232 * @oldval:	The expected value of the futex
233 * @newval:	The new value to try and assign the futex
234 *
235 * Implement cmpxchg using gcc atomic builtins.
236 * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
237 *
238 * Return the old futex value.
239 */
240static inline u_int32_t
241futex_cmpxchg(futex_t *uaddr, u_int32_t oldval, u_int32_t newval)
242{
243	return __sync_val_compare_and_swap(uaddr, oldval, newval);
244}
245
246/**
247 * futex_dec() - atomic decrement of the futex value
248 * @uaddr:	The address of the futex to be modified
249 *
250 * Return the new futex value.
251 */
252static inline u_int32_t
253futex_dec(futex_t *uaddr)
254{
255	return __sync_sub_and_fetch(uaddr, 1);
256}
257
258/**
259 * futex_inc() - atomic increment of the futex value
260 * @uaddr:	the address of the futex to be modified
261 *
262 * Return the new futex value.
263 */
264static inline u_int32_t
265futex_inc(futex_t *uaddr)
266{
267	return __sync_add_and_fetch(uaddr, 1);
268}
269
270/**
271 * futex_set() - atomic decrement of the futex value
272 * @uaddr:	the address of the futex to be modified
273 * @newval:	New value for the atomic_t
274 *
275 * Return the new futex value.
276 */
277static inline u_int32_t
278futex_set(futex_t *uaddr, u_int32_t newval)
279{
280	*uaddr = newval;
281	return newval;
282}
283
284#endif