Re: [PATCH bpf-next v3 08/11] bpf: Fall back to nospec for Spectre v1

On Thu, 1 May 2025 at 04:00, Luis Gerhorst wrote: > > This implements the core of the series and causes the verifier to fall > back to mitigating Spectre v1 using speculation barriers. The approach > was presented at LPC'24 [1] and RAID'24 [2]. > > If we find any forbidden behavior on a speculativ

Re: [PATCH bpf-next v3 08/11] bpf: Fall back to nospec for Spectre v1

Kumar Kartikeya Dwivedi writes: > Back when all of this surfaced, compiler folks came up with another > solution, to rely on Intel's guarantee that conditional moves are not > predicted. > > if (condition) { >mask = !condition ? 0UL : ~0UL; // CMOVcc >ptr &= mask; >x = *ptr; > } > > I

Re: [PATCH bpf-next v3 08/11] bpf: Fall back to nospec for Spectre v1

On Thu, 1 May 2025 at 10:00, Luis Gerhorst wrote: > > This implements the core of the series and causes the verifier to fall > back to mitigating Spectre v1 using speculation barriers. The approach > was presented at LPC'24 [1] and RAID'24 [2]. > > If we find any forbidden behavior on a speculativ

[PATCH bpf-next v3 08/11] bpf: Fall back to nospec for Spectre v1

This implements the core of the series and causes the verifier to fall back to mitigating Spectre v1 using speculation barriers. The approach was presented at LPC'24 [1] and RAID'24 [2]. If we find any forbidden behavior on a speculative path, we insert a nospec (e.g., lfence speculation barrier o