/* futex helper functions for glibc-internal use.
Copyright (C) 2020-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <sysdep.h>
#include <time.h>
#include <futex-internal.h>
#include <kernel-features.h>
#ifndef __ASSUME_TIME64_SYSCALLS
static int
__futex_abstimed_wait_common32 (unsigned int* futex_word,
unsigned int expected, int op,
const struct __timespec64* abstime,
int private, bool cancel)
{
struct timespec ts32, *pts32 = NULL;
if (abstime != NULL)
{
ts32 = valid_timespec64_to_timespec (*abstime);
pts32 = &ts32;
}
if (cancel)
return INTERNAL_SYSCALL_CANCEL (futex, futex_word, op, expected,
pts32, NULL /* Unused. */,
FUTEX_BITSET_MATCH_ANY);
else
return INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
pts32, NULL /* Unused. */,
FUTEX_BITSET_MATCH_ANY);
}
#endif /* ! __ASSUME_TIME64_SYSCALLS */
static int
__futex_abstimed_wait_common64 (unsigned int* futex_word,
unsigned int expected, int op,
const struct __timespec64* abstime,
int private, bool cancel)
{
if (cancel)
return INTERNAL_SYSCALL_CANCEL (futex_time64, futex_word, op, expected,
abstime, NULL /* Unused. */,
FUTEX_BITSET_MATCH_ANY);
else
return INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op, expected,
abstime, NULL /* Ununsed. */,
FUTEX_BITSET_MATCH_ANY);
}
static int
__futex_abstimed_wait_common (unsigned int* futex_word,
unsigned int expected, clockid_t clockid,
const struct __timespec64* abstime,
int private, bool cancel)
{
int err;
unsigned int clockbit;
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
return ETIMEDOUT;
if (! lll_futex_supported_clockid (clockid))
return EINVAL;
clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
#ifdef __ASSUME_TIME64_SYSCALLS
err = __futex_abstimed_wait_common64 (futex_word, expected, op, abstime,
private, cancel);
#else
bool need_time64 = abstime != NULL && !in_int32_t_range (abstime->tv_sec);
if (need_time64)
{
err = __futex_abstimed_wait_common64 (futex_word, expected, op, abstime,
private, cancel);
if (err == -ENOSYS)
err = -EOVERFLOW;
}
else
err = __futex_abstimed_wait_common32 (futex_word, expected, op, abstime,
private, cancel);
#endif
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
case -EINVAL:
case -EOVERFLOW: /* Passed absolute timeout uses 64 bit time_t type, but
underlying kernel does not support 64 bit time_t futex
syscalls. */
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
int
__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
clockid_t clockid,
const struct __timespec64* abstime, int private)
{
return __futex_abstimed_wait_common (futex_word, expected, clockid,
abstime, private, false);
}
libc_hidden_def (__futex_abstimed_wait64)
int
__futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
unsigned int expected, clockid_t clockid,
const struct __timespec64* abstime,
int private)
{
return __futex_abstimed_wait_common (futex_word, expected, clockid,
abstime, private, true);
}
libc_hidden_def (__futex_abstimed_wait_cancelable64)
int
__futex_lock_pi64 (int *futex_word, clockid_t clockid,
const struct __timespec64 *abstime, int private)
{
int err;
unsigned int clockbit = clockid == CLOCK_REALTIME
? FUTEX_CLOCK_REALTIME : 0;
int op_pi2 = __lll_private_flag (FUTEX_LOCK_PI2 | clockbit, private);
#if __ASSUME_FUTEX_LOCK_PI2
/* Assume __ASSUME_TIME64_SYSCALLS since FUTEX_LOCK_PI2 was added later. */
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op_pi2, 0, abstime);
#else
/* FUTEX_LOCK_PI does not support clock selection, so for CLOCK_MONOTONIC
the only option is to use FUTEX_LOCK_PI2. */
int op_pi1 = __lll_private_flag (FUTEX_LOCK_PI, private);
int op_pi = abstime != NULL && clockid != CLOCK_REALTIME ? op_pi2 : op_pi1;
# ifdef __ASSUME_TIME64_SYSCALLS
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op_pi, 0, abstime);
# else
bool need_time64 = abstime != NULL && !in_int32_t_range (abstime->tv_sec);
if (need_time64)
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op_pi, 0, abstime);
else
{
struct timespec ts32, *pts32 = NULL;
if (abstime != NULL)
{
ts32 = valid_timespec64_to_timespec (*abstime);
pts32 = &ts32;
}
err = INTERNAL_SYSCALL_CALL (futex, futex_word, op_pi, 0, pts32);
}
# endif /* __ASSUME_TIME64_SYSCALLS */
/* FUTEX_LOCK_PI2 is not available on this kernel. */
if (err == -ENOSYS)
err = -EINVAL;
#endif /* __ASSUME_FUTEX_LOCK_PI2 */
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
case -ESRCH:
case -EDEADLK:
case -EINVAL: /* This indicates either state corruption or that the kernel
found a waiter on futex address which is waiting via
FUTEX_WAIT or FUTEX_WAIT_BITSET. This is reported on
some futex_lock_pi usage (pthread_mutex_timedlock for
instance). */
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}