Messages in this thread | | | From | Guo Ren <> | Date | Fri, 28 Jul 2023 20:01:07 +0800 | Subject | Re: [PATCH v2] riscv: VMAP_STACK overflow detection thread-safe |
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On Tue, Jul 25, 2023 at 12:34 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > On Thu, Jul 20, 2023 at 8:06 AM Guo Ren <guoren@kernel.org> wrote: > > > > On Thu, Jul 20, 2023 at 8:19 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > > > > > Are you planning on resending this patch? I see it didn't gain much > > > traction last time, but this looks like a much cleaner solution for > > > selecting the overflow stack than having a `shadow_stack` and calling > > > to C to compute the per-CPU offset. The asm_per_cpu macro also would > > > come in handy when implementing CONFIG_SHADOW_CALL_STACK, which we'd > > > like to have on RISC-V too. > > I remember we ended up with an atomic lock mechanism instead of percpu > > offset, so what's the benefit of percpu style in overflow_stack path? > > The benefit is not needing a separate temporary stack and locks just Oh, you convinced me it could save another 1KB of memory.
Acked-by: Guo Ren <guoren@kernel.org>
> to compute the per-CPU offset. With CONFIG_SHADOW_CALL_STACK, we would > also need a "shadow" shadow call stack in this case before calling to > C code, at which point computing the offsets directly in assembly is > just significantly cleaner and without concurrency issues. > > Sami
-- Best Regards Guo Ren
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