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futex: Add sys_futex_wait()

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To complement sys_futex_waitv()/wake(), add sys_futex_wait(). This
syscall implements what was previously known as FUTEX_WAIT_BITSET
except it uses 'unsigned long' for the value and bitmask arguments,
takes timespec and clockid_t arguments for the absolute timeout and
uses FUTEX2 flags.

The 'unsigned long' allows FUTEX2_SIZE_U64 on 64bit platforms.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230921105248.164324363@noisy.programming.kicks-ass.net
This commit is contained in:
peterz@infradead.org 2023-09-21 12:45:12 +02:00 committed by Peter Zijlstra
parent 43adf84495
commit cb8c4312af
24 changed files with 156 additions and 57 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/alpha/kernel/syscalls/syscall.tbl
View File

@ -493,3 +493,4 @@
561 common cachestat sys_cachestat
562 common fchmodat2 sys_fchmodat2
563 common futex_wake sys_futex_wake
564 common futex_wait sys_futex_wait

1
arch/arm/tools/syscall.tbl
View File

@ -467,3 +467,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

2
arch/arm64/include/asm/unistd.h
View File

@ -39,7 +39,7 @@
#define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5)
#define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800)
#define __NR_compat_syscalls 455
#define __NR_compat_syscalls 456
#endif
#define __ARCH_WANT_SYS_CLONE

2
arch/arm64/include/asm/unistd32.h
View File

@ -913,6 +913,8 @@ __SYSCALL(__NR_cachestat, sys_cachestat)
__SYSCALL(__NR_fchmodat2, sys_fchmodat2)
#define __NR_futex_wake 454
__SYSCALL(__NR_futex_wake, sys_futex_wake)
#define __NR_futex_wait 455
__SYSCALL(__NR_futex_wait, sys_futex_wait)
/*
* Please add new compat syscalls above this comment and update

1
arch/ia64/kernel/syscalls/syscall.tbl
View File

@ -374,3 +374,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/m68k/kernel/syscalls/syscall.tbl
View File

@ -453,3 +453,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/microblaze/kernel/syscalls/syscall.tbl
View File

@ -459,3 +459,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/mips/kernel/syscalls/syscall_n32.tbl
View File

@ -392,3 +392,4 @@
451 n32 cachestat sys_cachestat
452 n32 fchmodat2 sys_fchmodat2
454 n32 futex_wake sys_futex_wake
455 n32 futex_wait sys_futex_wait

1
arch/mips/kernel/syscalls/syscall_n64.tbl
View File

@ -368,3 +368,4 @@
451 n64 cachestat sys_cachestat
452 n64 fchmodat2 sys_fchmodat2
454 n64 futex_wake sys_futex_wake
455 n64 futex_wait sys_futex_wait

1
arch/mips/kernel/syscalls/syscall_o32.tbl
View File

@ -441,3 +441,4 @@
451 o32 cachestat sys_cachestat
452 o32 fchmodat2 sys_fchmodat2
454 o32 futex_wake sys_futex_wake
455 o32 futex_wait sys_futex_wait

1
arch/parisc/kernel/syscalls/syscall.tbl
View File

@ -452,3 +452,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/powerpc/kernel/syscalls/syscall.tbl
View File

@ -540,3 +540,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/s390/kernel/syscalls/syscall.tbl
View File

@ -456,3 +456,4 @@
451 common cachestat sys_cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait sys_futex_wait

1
arch/sh/kernel/syscalls/syscall.tbl
View File

@ -456,3 +456,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/sparc/kernel/syscalls/syscall.tbl
View File

@ -499,3 +499,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

1
arch/x86/entry/syscalls/syscall_32.tbl
View File

@ -458,3 +458,4 @@
451 i386 cachestat sys_cachestat
452 i386 fchmodat2 sys_fchmodat2
454 i386 futex_wake sys_futex_wake
455 i386 futex_wait sys_futex_wait

1
arch/x86/entry/syscalls/syscall_64.tbl
View File

@ -376,6 +376,7 @@
452 common fchmodat2 sys_fchmodat2
453 64 map_shadow_stack sys_map_shadow_stack
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
#
# Due to a historical design error, certain syscalls are numbered differently

1
arch/xtensa/kernel/syscalls/syscall.tbl
View File

@ -424,3 +424,4 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait

4
include/linux/syscalls.h
View File

@ -552,6 +552,10 @@ asmlinkage long sys_futex_waitv(struct futex_waitv *waiters,
asmlinkage long sys_futex_wake(void __user *uaddr, unsigned long mask, int nr, unsigned int flags);
asmlinkage long sys_futex_wait(void __user *uaddr, unsigned long val, unsigned long mask,
unsigned int flags, struct __kernel_timespec __user *timespec,
clockid_t clockid);
asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp,
struct __kernel_timespec __user *rmtp);
asmlinkage long sys_nanosleep_time32(struct old_timespec32 __user *rqtp,

4
include/uapi/asm-generic/unistd.h
View File

@ -824,9 +824,11 @@ __SYSCALL(__NR_cachestat, sys_cachestat)
__SYSCALL(__NR_fchmodat2, sys_fchmodat2)
#define __NR_futex_wake 454
__SYSCALL(__NR_futex_wake, sys_futex_wake)
#define __NR_futex_wait 455
__SYSCALL(__NR_futex_wait, sys_futex_wait)
#undef __NR_syscalls
#define __NR_syscalls 455
#define __NR_syscalls 456
/*
* 32 bit systems traditionally used different

3
kernel/futex/futex.h
View File

@ -332,6 +332,9 @@ extern int futex_requeue(u32 __user *uaddr1, unsigned int flags,
u32 __user *uaddr2, int nr_wake, int nr_requeue,
u32 *cmpval, int requeue_pi);
extern int __futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
struct hrtimer_sleeper *to, u32 bitset);
extern int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
ktime_t *abs_time, u32 bitset);

120
kernel/futex/syscalls.c
View File

@ -221,6 +221,46 @@ static int futex_parse_waitv(struct futex_vector *futexv,
return 0;
}
static int futex2_setup_timeout(struct __kernel_timespec __user *timeout,
clockid_t clockid, struct hrtimer_sleeper *to)
{
int flag_clkid = 0, flag_init = 0;
struct timespec64 ts;
ktime_t time;
int ret;
if (!timeout)
return 0;
if (clockid == CLOCK_REALTIME) {
flag_clkid = FLAGS_CLOCKRT;
flag_init = FUTEX_CLOCK_REALTIME;
}
if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC)
return -EINVAL;
if (get_timespec64(&ts, timeout))
return -EFAULT;
/*
* Since there's no opcode for futex_waitv, use
* FUTEX_WAIT_BITSET that uses absolute timeout as well
*/
ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time);
if (ret)
return ret;
futex_setup_timer(&time, to, flag_clkid, 0);
return 0;
}
static inline void futex2_destroy_timeout(struct hrtimer_sleeper *to)
{
hrtimer_cancel(&to->timer);
destroy_hrtimer_on_stack(&to->timer);
}
/**
* sys_futex_waitv - Wait on a list of futexes
* @waiters: List of futexes to wait on
@ -250,8 +290,6 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters,
{
struct hrtimer_sleeper to;
struct futex_vector *futexv;
struct timespec64 ts;
ktime_t time;
int ret;
/* This syscall supports no flags for now */
@ -261,30 +299,8 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters,
if (!nr_futexes || nr_futexes > FUTEX_WAITV_MAX || !waiters)
return -EINVAL;
if (timeout) {
int flag_clkid = 0, flag_init = 0;
if (clockid == CLOCK_REALTIME) {
flag_clkid = FLAGS_CLOCKRT;
flag_init = FUTEX_CLOCK_REALTIME;
}
if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC)
return -EINVAL;
if (get_timespec64(&ts, timeout))
return -EFAULT;
/*
* Since there's no opcode for futex_waitv, use
* FUTEX_WAIT_BITSET that uses absolute timeout as well
*/
ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time);
if (ret)
return ret;
futex_setup_timer(&time, &to, flag_clkid, 0);
}
if (timeout && (ret = futex2_setup_timeout(timeout, clockid, &to)))
return ret;
futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL);
if (!futexv) {
@ -299,10 +315,8 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters,
kfree(futexv);
destroy_timer:
if (timeout) {
hrtimer_cancel(&to.timer);
destroy_hrtimer_on_stack(&to.timer);
}
if (timeout)
futex2_destroy_timeout(&to);
return ret;
}
@ -336,6 +350,52 @@ SYSCALL_DEFINE4(futex_wake,
return futex_wake(uaddr, FLAGS_STRICT | flags, nr, mask);
}
/*
* sys_futex_wait - Wait on a futex
* @uaddr: Address of the futex to wait on
* @val: Value of @uaddr
* @mask: bitmask
* @flags: FUTEX2 flags
* @timeout: Optional absolute timeout
* @clockid: Clock to be used for the timeout, realtime or monotonic
*
* Identical to the traditional FUTEX_WAIT_BITSET op, except it is part of the
* futex2 familiy of calls.
*/
SYSCALL_DEFINE6(futex_wait,
void __user *, uaddr,
unsigned long, val,
unsigned long, mask,
unsigned int, flags,
struct __kernel_timespec __user *, timeout,
clockid_t, clockid)
{
struct hrtimer_sleeper to;
int ret;
if (flags & ~FUTEX2_VALID_MASK)
return -EINVAL;
flags = futex2_to_flags(flags);
if (!futex_flags_valid(flags))
return -EINVAL;
if (!futex_validate_input(flags, val) ||
!futex_validate_input(flags, mask))
return -EINVAL;
if (timeout && (ret = futex2_setup_timeout(timeout, clockid, &to)))
return ret;
ret = __futex_wait(uaddr, flags, val, timeout ? &to : NULL, mask);
if (timeout)
futex2_destroy_timeout(&to);
return ret;
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(set_robust_list,
struct compat_robust_list_head __user *, head,

61
kernel/futex/waitwake.c
View File

@ -632,20 +632,18 @@ int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
return ret;
}
int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset)
int __futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
struct hrtimer_sleeper *to, u32 bitset)
{
struct hrtimer_sleeper timeout, *to;
struct restart_block *restart;
struct futex_hash_bucket *hb;
struct futex_q q = futex_q_init;
struct futex_hash_bucket *hb;
int ret;
if (!bitset)
return -EINVAL;
q.bitset = bitset;
to = futex_setup_timer(abs_time, &timeout, flags,
current->timer_slack_ns);
retry:
/*
* Prepare to wait on uaddr. On success, it holds hb->lock and q
@ -653,18 +651,17 @@ int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time
*/
ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
if (ret)
goto out;
return ret;
/* futex_queue and wait for wakeup, timeout, or a signal. */
futex_wait_queue(hb, &q, to);
/* If we were woken (and unqueued), we succeeded, whatever. */
ret = 0;
if (!futex_unqueue(&q))
goto out;
ret = -ETIMEDOUT;
return 0;
if (to && !to->task)
goto out;
return -ETIMEDOUT;
/*
* We expect signal_pending(current), but we might be the
@ -673,24 +670,38 @@ int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time
if (!signal_pending(current))
goto retry;
ret = -ERESTARTSYS;
if (!abs_time)
goto out;
return -ERESTARTSYS;
}
restart = &current->restart_block;
restart->futex.uaddr = uaddr;
restart->futex.val = val;
restart->futex.time = *abs_time;
restart->futex.bitset = bitset;
restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset)
{
struct hrtimer_sleeper timeout, *to;
struct restart_block *restart;
int ret;
ret = set_restart_fn(restart, futex_wait_restart);
to = futex_setup_timer(abs_time, &timeout, flags,
current->timer_slack_ns);
out:
if (to) {
hrtimer_cancel(&to->timer);
destroy_hrtimer_on_stack(&to->timer);
ret = __futex_wait(uaddr, flags, val, to, bitset);
/* No timeout, nothing to clean up. */
if (!to)
return ret;
hrtimer_cancel(&to->timer);
destroy_hrtimer_on_stack(&to->timer);
if (ret == -ERESTARTSYS) {
restart = &current->restart_block;
restart->futex.uaddr = uaddr;
restart->futex.val = val;
restart->futex.time = *abs_time;
restart->futex.bitset = bitset;
restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
return set_restart_fn(restart, futex_wait_restart);
}
return ret;
}

1
kernel/sys_ni.c
View File

@ -88,6 +88,7 @@ COND_SYSCALL(get_robust_list);
COND_SYSCALL_COMPAT(get_robust_list);
COND_SYSCALL(futex_waitv);
COND_SYSCALL(futex_wake);
COND_SYSCALL(futex_wait);
COND_SYSCALL(kexec_load);
COND_SYSCALL_COMPAT(kexec_load);
COND_SYSCALL(init_module);