9.4 arch_prctl ¶

int arch_prctl(int code, uint64_t argument);

This syscall interacts with architecture-specific thread-local storage. For x86_64, these are the available codes:

ARCH_SET_FS (1)

Sets argument as the current thread’s FS.

ARCH_GET_FS (2)

Stores the current thread’s FS into the variable pointed to by argument.

ARCH_SET_GS (3)

Sets argument as the current thread’s FS.

ARCH_GET_GS (4)

Stores the current thread’s GS into the variable pointed to by argument.

This syscall returns 0 on success, and -1 on failure. errno is to be set to the following values on failure:

• EINVAL: code is not valid.
• EFAULT: argument is outside the available address space.