futex_wait
Implemented in Antinomie 0.7.0 · Syscall list
Synopsis
Section titled “Synopsis”long futex_wait(void *uaddr, unsigned long val, unsigned long mask, unsigned int flags, struct __kernel_timespec *timespec, clockid_t clockid);| Number (x86-64) | 455 |
| ABI | common |
| Kernel entry point | sys_futex_wait |
This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.
Description
Section titled “Description”Waits on a futex word until it is woken or a timeout, using the newer futex2 interface.
Arguments
Section titled “Arguments”| Name | Type | Meaning |
|---|---|---|
uaddr (arg0) |
void * |
Address of a 32-bit futex word. |
val (arg1) |
unsigned long |
A value. |
mask (arg2) |
unsigned long |
Bit mask. |
flags (arg3) |
unsigned int |
Option flags that change the behavior of the call. |
timespec (arg4) |
struct __kernel_timespec * |
Timeout. |
clockid (arg5) |
clockid_t |
Clock id. |
Return value
Section titled “Return value”On success: 0.
In an Antinomie trace the Return column and the ret filter field show the raw kernel return value. On failure that is the negative errno, for example -2 for ENOENT, not the -1 plus errno that the libc wrapper gives. syscall.errno holds the positive errno and syscall.success is false.
Common errors
Section titled “Common errors”| Raw return | Name | Meaning |
|---|---|---|
-11 |
EAGAIN |
The call would block, or a resource is temporarily unavailable. |
-4 |
EINTR |
The call was interrupted by a signal. |
-110 |
ETIMEDOUT |
The operation timed out. |
Man page
Section titled “Man page”Captured by Antinomie
Section titled “Captured by Antinomie”Coverage mark: Implemented. Every pointer argument has a capture rule in the pinned kernel patch and none of them records a “no decoder”, “address only” or “not observed” gap on any code path. Individual values can still be incomplete on a particular call; see the capture statuses.
Every call is recorded as an Entry record (the six argument words and the pointees copied at entry) and an Exit record (the return value and the pointees copied at exit).
Arguments
Section titled “Arguments”| Argument | When | How | Recorded field key | Condition |
|---|---|---|---|---|
uaddr (arg0) |
Entry | the pointer itself, as a raw word | args.0, args.raw[0] |
|
| ↳ pointee | Entry | the 32-bit futex word; “invalid extent” if the size flag is not 32 bits | arg0.futex.observed |
always |
val (arg1) |
Entry | raw scalar word | args.1, args.val |
|
mask (arg2) |
Entry | raw scalar word | args.2, args.mask |
|
flags (arg3) |
Entry | raw scalar word; Syscall Trace also decodes it into flag names (futex2 group), listing unknown bits separately |
args.3, args.flags |
|
timespec (arg4) |
Entry | the pointer itself, as a raw word | args.4, args.raw[4] |
|
| ↳ pointee | Entry | structure timespec |
arg4.timeout |
the pointer is not NULL |
clockid (arg5) |
Entry | raw scalar word | args.5, args.clockid |
Filter fields
Section titled “Filter fields”- Result:
ret,syscall.errno,syscall.success,syscall.duration_ns. - Argument words:
args.uaddr(arg0),args.val(arg1),args.mask(arg2),args.flags(arg3),args.timespec(arg4),args.clockid(arg5);args.0toargs.5by position. - Structure
timespec[2]behindtimespec(arg4):args.timespec.<member>fortv_nsec,tv_sec.
See Syscall Trace filter for the full syntax.
For what the capture statuses mean, see Capture statuses. For what is never recorded, see Known gaps.