[PATCH RFC] riscv: Do not handle break traps from kernel as nmi

[Peter Zijlstra]

On Wed, Sep 03, 2025 at 07:54:29PM +0000, Alexandre Ghiti wrote:
> kprobe has been broken on riscv for quite some time. There is an attempt
> [1] to fix that which actually works. This patch works because it enables
> ARCH_HAVE_NMI_SAFE_CMPXCHG and that makes the ring buffer allocation
> succeed when handling a kprobe because we handle *all* kprobes in nmi
> context. We do so because Peter advised us to treat all kernel traps as
> nmi [2].
> 
> But that does not seem right for kprobe handling, so instead, treat
> break traps from kernel as non-nmi.

You can put a kprobe inside: local_irq_disable(), no? Inside any random
spinlock region in fact. How is the probe then not NMI like?