set_tid_address

Partial in Antinomie 0.7.0 · Syscall list

Synopsis

long set_tid_address(int *tidptr);

Number (x86-64)	218
ABI	common
Kernel entry point	sys_set_tid_address

This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.

Description

Sets the address the kernel clears, and wakes a futex on, when the thread exits.

Arguments

Name	Type	Meaning
tidptr (arg0)	int *	Pointer to a thread id word.

Return value

On success: the caller’s thread id.

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.

Man page

set_tid_address(2) on man7.org

Captured by Antinomie

Coverage mark: Partial. The thread id word is zeroed and futex-woken by the kernel when the thread exits, so it is recorded with the “not observed asynchronously” status.

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

Argument	When	How	Recorded field key	Condition
tidptr (arg0)	Entry	the pointer itself, as a raw word	args.0, args.raw[0]
↳ pointee	Entry	pid_t (4 bytes), status “not observed asynchronously”	arg0.clear_child_tid	always

Filter fields

• Result: ret, syscall.errno, syscall.success, syscall.duration_ns.
• Argument words: args.tidptr (arg0); args.0 to args.5 by position.
• Structure wait_status behind tidptr (arg0): args.tidptr.<member> for value.

See Syscall Trace filter for the full syntax.

Known gaps

• The kernel zeroes this word and wakes a futex on it when the thread exits, which Antinomie does not see.
• See the coverage mark above for the code paths that record a gap.

For what the capture statuses mean, see Capture statuses. For what is never recorded, see Known gaps.