效绵县 Discovering Useful Instruction Sequences in Libc The Galileo Algorithm: Algorithm GALILEO: create a node,root,representing the ret instruction; place root in the trie; for pos from 1 to textseg len do: if the byte at pos is c3,i.e.,a ret instruction,then: call BUILDFROM(pos,root). Procedure BUILDFROM(index pos,instruction parent_insn): for step from 1 to max insn_len do: if bytes [(pos-step)...(pos-1)decode as a valid instruction insn then: ensure insn is in the trie as a child of parent insn; if insn isn't boring then: call BUILDFROM(pos-step,insn). 2023/2/7 92023/2/7 9 Discovering Useful Instruction Sequences in Libc The Galileo Algorithm: