getcpu

Implemented in Antinomie 0.7.0 · Syscall list

Synopsis

long getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *cache);

Number (x86-64)	309
ABI	common
Kernel entry point	sys_getcpu

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

Description

Reports the CPU and NUMA node on which the thread is running.

Arguments

Name	Type	Meaning
cpu (arg0)	unsigned int *	CPU number.
node (arg1)	unsigned int *	NUMA node number.
cache (arg2)	struct getcpu_cache *	Unused cache pointer, must be NULL.

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.

Man page

getcpu(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
cpu (arg0)	Entry	the pointer itself, as a raw word	args.0, args.raw[0]
↳ pointee	Exit	u32 CPU number	arg0.cpu	result is 0 and the pointer is not NULL
↳ pointee	Exit	structure unsigned_int (fixed size)	arg0.data	result is 0
node (arg1)	Entry	the pointer itself, as a raw word	args.1, args.raw[1]
↳ pointee	Exit	u32 NUMA node	arg1.node	result is 0 and the pointer is not NULL
↳ pointee	Exit	structure unsigned_int (fixed size)	arg1.data	result is 0
cache (arg2)	Entry	the pointer itself, as a raw word	args.2, args.raw[2]
↳ pointee	Entry	address only, status “not written”	arg2.ignored_cache	the pointer is not NULL

Filter fields

• Result: ret, syscall.errno, syscall.success, syscall.duration_ns.
• Argument words: args.cpu (arg0), args.node (arg1), args.cache (arg2); args.0 to args.5 by position.
• Structure wait_status behind cpu (arg0): args.cpu.<member> for value.
• Structure wait_status behind node (arg1): args.node.<member> for value.

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.