On 2025-02-10 12:49:45 [+0000], Mark Rutland wrote:

Hi,

Hi,

I don't have an immediate suggestion; I'll need to go think about this
for a bit. Unfortunatealy, there are several nested cans of worms here.
:/

In theory, we can go split out the EL0 "debug exceptions" into separate
handlers, and wouldn't generally need to disable preemption for things
like BRK or single-step.

However, it's not immediately clear to me how we could handle
watchpoints or breakpoints, since for those preemption/interruption
could change the HW state under our feet, and we rely on single-step to
skip past the watchpoint/breakpoint after it is handled.

Couldn't you delay sending signals until after the preempt-disable
section? 

That, and last I looked reworking this we'd need to do a larger rework
to split out those "debug exceptions" because of that way that currently
bounces through the fault handling ligic in arch/arm64/mm/.

Mark.

Sebastian