Messages in this thread | | | From | Sami Tolvanen <> | Date | Mon, 24 Jul 2023 10:03:14 -0700 | Subject | Re: [PATCH v2] riscv: VMAP_STACK overflow detection thread-safe |
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On Thu, Jul 20, 2023 at 8:10 AM Guo Ren <guoren@kernel.org> wrote: > > On Thu, Nov 24, 2022 at 5:48 PM Deepak Gupta <debug@rivosinc.com> wrote: > > +.macro asm_per_cpu dst sym tmp > > + REG_L \tmp, TASK_TI_CPU_NUM(tp) > > + slli \tmp, \tmp, PER_CPU_OFFSET_SHIFT > > + la \dst, __per_cpu_offset > > + add \dst, \dst, \tmp > > + REG_L \tmp, 0(\dst) > > + la \dst, \sym > > + add \dst, \dst, \tmp > > +.endm > It's a tricky implementation, and we can't maintain it here because it > depends on percpu design.
I can certainly understand this concern, but AFAICT this part of the percpu code hasn't changed in ~14 years, so adding an assembly macro for the computation shouldn't be a huge maintenance burden. arm64 also performs a similar computation in assembly (starting with commit 3d8c1a013d78) and I don't see their implementation needing constant maintenance since then.
Sami
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