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 25 typedef 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 * futex() - SYS_futex syscall wrapper 63 * @uaddr: address of first futex 64 * @op: futex op code 65 * @val: typically expected value of uaddr, but varies by op 66 * @timeout: typically an absolute struct timespec (except where noted 67 * otherwise). Overloaded by some ops 68 * @uaddr2: address of second futex for some ops\ 69 * @val3: varies by op 70 * @opflags: flags to be bitwise OR'd with op, such as FUTEX_PRIVATE_FLAG 71 * 72 * futex() is used by all the following futex op wrappers. It can also be 73 * used for misuse and abuse testing. Generally, the specific op wrappers 74 * should be used instead. It is a macro instead of an static inline function as 75 * some of the types over overloaded (timeout is used for nr_requeue for 76 * example). 77 * 78 * These argument descriptions are the defaults for all 79 * like-named arguments in the following wrappers except where noted below. 80 */ 81 #define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \ 82 syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3) 83 84 /** 85 * futex_wait() - block on uaddr with optional timeout 86 * @timeout: relative timeout 87 */ 88 static inline int 89 futex_wait(futex_t *uaddr, futex_t val, struct timespec *timeout, int opflags) 90 { 91 return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags); 92 } 93 94 /** 95 * futex_wake() - wake one or more tasks blocked on uaddr 96 * @nr_wake: wake up to this many tasks 97 */ 98 static inline int 99 futex_wake(futex_t *uaddr, int nr_wake, int opflags) 100 { 101 return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags); 102 } 103 104 /** 105 * futex_wait_bitset() - block on uaddr with bitset 106 * @bitset: bitset to be used with futex_wake_bitset 107 */ 108 static inline int 109 futex_wait_bitset(futex_t *uaddr, futex_t val, struct timespec *timeout, 110 u_int32_t bitset, int opflags) 111 { 112 return futex(uaddr, FUTEX_WAIT_BITSET, val, timeout, NULL, bitset, 113 opflags); 114 } 115 116 /** 117 * futex_wake_bitset() - wake one or more tasks blocked on uaddr with bitset 118 * @bitset: bitset to compare with that used in futex_wait_bitset 119 */ 120 static inline int 121 futex_wake_bitset(futex_t *uaddr, int nr_wake, u_int32_t bitset, int opflags) 122 { 123 return futex(uaddr, FUTEX_WAKE_BITSET, nr_wake, NULL, NULL, bitset, 124 opflags); 125 } 126 127 /** 128 * futex_lock_pi() - block on uaddr as a PI mutex 129 * @detect: whether (1) or not (0) to perform deadlock detection 130 */ 131 static inline int 132 futex_lock_pi(futex_t *uaddr, struct timespec *timeout, int detect, 133 int opflags) 134 { 135 return futex(uaddr, FUTEX_LOCK_PI, detect, timeout, NULL, 0, opflags); 136 } 137 138 /** 139 * futex_unlock_pi() - release uaddr as a PI mutex, waking the top waiter 140 */ 141 static inline int 142 futex_unlock_pi(futex_t *uaddr, int opflags) 143 { 144 return futex(uaddr, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0, opflags); 145 } 146 147 /** 148 * futex_wake_op() - FIXME: COME UP WITH A GOOD ONE LINE DESCRIPTION 149 */ 150 static inline int 151 futex_wake_op(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_wake2, 152 int wake_op, int opflags) 153 { 154 return futex(uaddr, FUTEX_WAKE_OP, nr_wake, nr_wake2, uaddr2, wake_op, 155 opflags); 156 } 157 158 /** 159 * futex_requeue() - requeue without expected value comparison, deprecated 160 * @nr_wake: wake up to this many tasks 161 * @nr_requeue: requeue up to this many tasks 162 * 163 * Due to its inherently racy implementation, futex_requeue() is deprecated in 164 * favor of futex_cmp_requeue(). 165 */ 166 static inline int 167 futex_requeue(futex_t *uaddr, futex_t *uaddr2, int nr_wake, int nr_requeue, 168 int opflags) 169 { 170 return futex(uaddr, FUTEX_REQUEUE, nr_wake, nr_requeue, uaddr2, 0, 171 opflags); 172 } 173 174 /** 175 * futex_cmp_requeue() - requeue tasks from uaddr to uaddr2 176 * @nr_wake: wake up to this many tasks 177 * @nr_requeue: requeue up to this many tasks 178 */ 179 static inline int 180 futex_cmp_requeue(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake, 181 int nr_requeue, int opflags) 182 { 183 return futex(uaddr, FUTEX_CMP_REQUEUE, nr_wake, nr_requeue, uaddr2, 184 val, opflags); 185 } 186 187 /** 188 * futex_wait_requeue_pi() - block on uaddr and prepare to requeue to uaddr2 189 * @uaddr: non-PI futex source 190 * @uaddr2: PI futex target 191 * 192 * This is the first half of the requeue_pi mechanism. It shall always be 193 * paired with futex_cmp_requeue_pi(). 194 */ 195 static inline int 196 futex_wait_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2, 197 struct timespec *timeout, int opflags) 198 { 199 return futex(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0, 200 opflags); 201 } 202 203 /** 204 * futex_cmp_requeue_pi() - requeue tasks from uaddr to uaddr2 (PI aware) 205 * @uaddr: non-PI futex source 206 * @uaddr2: PI futex target 207 * @nr_wake: wake up to this many tasks 208 * @nr_requeue: requeue up to this many tasks 209 */ 210 static inline int 211 futex_cmp_requeue_pi(futex_t *uaddr, futex_t val, futex_t *uaddr2, int nr_wake, 212 int nr_requeue, int opflags) 213 { 214 return futex(uaddr, FUTEX_CMP_REQUEUE_PI, nr_wake, nr_requeue, uaddr2, 215 val, opflags); 216 } 217 218 /** 219 * futex_cmpxchg() - atomic compare and exchange 220 * @uaddr: The address of the futex to be modified 221 * @oldval: The expected value of the futex 222 * @newval: The new value to try and assign the futex 223 * 224 * Implement cmpxchg using gcc atomic builtins. 225 * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html 226 * 227 * Return the old futex value. 228 */ 229 static inline u_int32_t 230 futex_cmpxchg(futex_t *uaddr, u_int32_t oldval, u_int32_t newval) 231 { 232 return __sync_val_compare_and_swap(uaddr, oldval, newval); 233 } 234 235 /** 236 * futex_dec() - atomic decrement of the futex value 237 * @uaddr: The address of the futex to be modified 238 * 239 * Return the new futex value. 240 */ 241 static inline u_int32_t 242 futex_dec(futex_t *uaddr) 243 { 244 return __sync_sub_and_fetch(uaddr, 1); 245 } 246 247 /** 248 * futex_inc() - atomic increment of the futex value 249 * @uaddr: the address of the futex to be modified 250 * 251 * Return the new futex value. 252 */ 253 static inline u_int32_t 254 futex_inc(futex_t *uaddr) 255 { 256 return __sync_add_and_fetch(uaddr, 1); 257 } 258 259 /** 260 * futex_set() - atomic decrement of the futex value 261 * @uaddr: the address of the futex to be modified 262 * @newval: New value for the atomic_t 263 * 264 * Return the new futex value. 265 */ 266 static inline u_int32_t 267 futex_set(futex_t *uaddr, u_int32_t newval) 268 { 269 *uaddr = newval; 270 return newval; 271 } 272 273 #endif 274