Again, With More Feeling: sparc64

• GOT is never changed after the library is loaded

• initial PLT stubs load index and jump to common stub, which does call to dynamic linker

• dynamic linker updates the PLT code sequence to jump to the final address

  • many possible sequences depending on the relative and absolute address

    • within 2^21 of the PLT entry? within 2^31 of address zero?

    • hard to exercise, ergo buggy: incorrect offset calculations, wrong ASM

  • PLT could be called by another thread while changing it

    • instruction sequence must always be safely executable

      • change it in two steps