getting crashes when I press a lot of keys. processes with weird stacks too (e.g. a userspace process with sp set to an empty kernel stack), so I suspect either stack overflows or bad returns from kernel mode
from the debug output, a crash always seems to happen right after an interrupt in kernel mode (this can happen when allocating memory and it needs to swap in more pages)
... why did this never break before?
(because the kernel typically allocates blocks of about 32 bytes long, and swapping happens once every 4096 bytes. so each allocation has less than 1% chance of triggering a nested exception, and perhaps not all of those cause issues. and most kernel allocation happens before userspace code runs so there are no exception registers to mess up.)
... why is it still broken?
oh i am a silly goose. nested interrupts will use the same object stack, overwriting the outer interrupt's object stack
yes! it works!!!! yesssssss!!!!
a nested interrupt will overwrite the saved registers, so I should probably stash those somewhere when there may be nested interrupts!