lowRISC / lowRISC/ibex

[rtl] Dummy instruction enhancements

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#885 1 comment 0 reactions 1 assignee View on GitHub

@tomeroberts is already working on this.

Since May 21, 2020.

Type:Enhancement
Dominant language
SystemVerilog
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Avg merge
5d 23h
Merged PRs (30d)
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Description

  • Wider control of insertion frequency, all the way down every other instruction
  • Add dummy instructions when IF stage stalls to hide I$ timing side-channel
  • Add some scrambling to LFSR output
  • Replace NOPs with dummy instructions (idea from CG since algorithm writers sometimes add NOPs for obfuscation, but their power signature can be a bit obvious)
  • More software control over the types of instructions inserted and their weighting and/or
  • Bias instruction type towards recently executed actual instructions

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