This is one of the ELF section stack manipulation directives. The others are
.section (see Section),
.subsection (see SubSection),
.pushsection (see PushSection), and
This directive swaps the current section (and subsection) with most recently
referenced section (and subsection) prior to this one. Multiple
.previous directives in a row will flip between two sections (and their
In terms of the section stack, this directive swaps the current section with the top section on the section stack.