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OoO risc-v processors are also vulnerable to spectre...
by deepnotderp 8y ago
OoO risc-v processors are also vulnerable to spectre...
- snvzz 8y agoWhich RISC-V processors?
- deepnotderp 8y agoAny of them unless they have specific modifications for mitigation.
- deepnotderp 8y agoAny of them that uses speculative execution to be clear, if it wasn't apparent.
- snvzz 8y agoPotentially.
- wlesieutre 8y agoRISC-V foundation says not: >No announced RISC-V silicon is susceptible, and the popular open-source RISC-V Rocket processor is unaffected as it does not perform memory accesses speculatively. https://www.techpowerup.com/240310/risc-v-foundation-issues-statement-on-spectre-meltdown-exploits https://www.techpowerup.com/240310/risc-v-foundation-issues-... Do you have a source?
- deepnotderp 8y agoThe rocket core isn't OoO, they even say so...
- wlesieutre 8y agoIt says right there "No announced RISC-V silicon is susceptible." Does someone actually make a RISC-V processor with out of order execution? Or is this a "They're going to make one eventually, so they'll have to address Spectre attacks before that happens" problem?
- deepnotderp 8y agoYeah, no shit, because there's no major RISC-V silicon that's OoO. If you solely look at ARM cores that don't speculate, then ARM cores aren't vulnerable either. Also pretty sure BOOMv2 has been taped out: https://content.riscv.org/wp-content/uploads/2017/12/Wed0936-BOOM-v2-An-Open-Source-Out-of-Order-RISC-V-Core-Celio.pdf https://content.riscv.org/wp-content/uploads/2017/12/Wed0936...
- Symmetry 8y agoWell, the A8 was vulnerable despite being in order but it was a mediocre design with an unusually long pipeline for a core of its class. Of course even in order core speculate a little based on predicting branches and their pipeline lengths but there's a very limited window for things to go wrong without going OoO and almost all in order cores can't execute enough dependent instructions to leak data without realizing they took the wrong branch.
- deepnotderp 8y agoYes, to be more precise, anything doing anything speculative with memory.