7.75 .previous

This is one of the ELF section stack manipulation directives. The others are .section (see .section name), .subsection (see .subsection name), .pushsection (see .pushsection name [, subsection] [, "flags"[, @type[,arguments]]]), and .popsection (see .popsection).

This directive swaps the current section (and subsection) with most recently referenced section/subsection pair prior to this one. Multiple .previous directives in a row will flip between two sections (and their subsections). For example:

.section A
 .subsection 1
  .word 0x1234
 .subsection 2
  .word 0x5678
.previous
 .word 0x9abc

Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of section A. Whilst:

.section A
.subsection 1
  # Now in section A subsection 1
  .word 0x1234
.section B
.subsection 0
  # Now in section B subsection 0
  .word 0x5678
.subsection 1
  # Now in section B subsection 1
  .word 0x9abc
.previous
  # Now in section B subsection 0
  .word 0xdef0

Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of section B and 0x9abc into subsection 1 of section B.

In terms of the section stack, this directive swaps the current section with the top section on the section stack.