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