sigaltstack

Implemented in Antinomie 0.7.0 · Syscall list

Synopsis

long sigaltstack(const struct sigaltstack *uss, struct sigaltstack *uoss);

Number (x86-64)	131
ABI	64
Kernel entry point	sys_sigaltstack

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

Description

Sets or reads the alternate stack used by signal handlers.

Arguments

Name	Type	Meaning
uss (arg0)	const struct sigaltstack *	Pointer to the new alternate stack.
uoss (arg1)	struct sigaltstack *	Pointer to a buffer for the old alternate stack.

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

Raw return	Name	Meaning
-14	EFAULT	A pointer argument points outside the accessible address space.
-1	EPERM	The operation is not permitted for this process.

Man page

sigaltstack(2) on man7.org

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

Argument	When	How	Recorded field key	Condition
uss (arg0)	Entry	the pointer itself, as a raw word	args.0, args.raw[0]
↳ pointee	Entry	structure stack_t (24 bytes), the new alternate stack	arg0.stack	the pointer is not NULL
uoss (arg1)	Entry	the pointer itself, as a raw word	args.1, args.raw[1]
↳ pointee	Exit	structure stack_t (24 bytes), the old alternate stack	arg1.stack	result is 0 and the pointer is not NULL

Filter fields

• Result: ret, syscall.errno, syscall.success, syscall.duration_ns.
• Argument words: args.uss (arg0), args.uoss (arg1); args.0 to args.5 by position.
• Structure stack_t behind uss (arg0): args.uss.<member> for ss_flags, ss_size, ss_sp.
• Structure stack_t behind uoss (arg1): args.uoss.<member> for ss_flags, ss_size, ss_sp.

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.