/* 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 <dvhart@linux.intel.com> * * HISTORY * 2009-Nov-6: Initial version by Darren Hart <dvhart@linux.intel.com> * *****************************************************************************/ #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 /* * SYS_futex is expected from system C library, in glibc some 32-bit * architectures (e.g. RV32) are using 64-bit time_t, therefore it doesn't have * SYS_futex defined but just SYS_futex_time64. Define SYS_futex as * SYS_futex_time64 in this situation to ensure the compilation and the * compatibility. */ #if !defined(SYS_futex) && defined(SYS_futex_time64) #define SYS_futex SYS_futex_time64 #endif /* * On 32bit systems if we use "-D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64" or if * we are using a newer compiler then the size of the timestamps will be 64bit, * however, the SYS_futex will still point to the 32bit futex system call. */ #if __SIZEOF_POINTER__ == 4 && defined(SYS_futex_time64) && \ defined(_TIME_BITS) && _TIME_BITS == 64 # undef SYS_futex # define SYS_futex SYS_futex_time64 #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
