Re: reliable reproducer, was Re: core dump analysis

Michael Schmitz
2023-04-21T09:18:22Z

Hi Finn,

Am 21.04.2023 um 20:30 schrieb Finn Thain:
> On Fri, 21 Apr 2023, Michael Schmitz wrote:
>
>>
>> How often did a page fault happen when executing moveml, in other
>> programs?
>>
>
> The printk() I placed in bus_error030() was conditional on the short word
> at the instruction pointer. It didn't consider all forms of movem, just
> 0x48e7 which is the start of "moveml X,%sp@-". This matched page faults in
> many of the programs that executed while booting to single user mode. I
> suppose most of them don't use signal handlers in the same way dash does
> otherwise they would probably be unreliable too.

OK; so too much noise unless filtered on the command name...

I'll try first to get register state at the time of signal delivery from
the sa_sigaction handler's ucontext parameter to see where the signal
stack falls in relation to the call frames from your rec() function on
the stack (and what the register contents were). Hope that won't be too
noisy ... Then see how that changes with bus error handling forcing
signal delivery.

Shame we don't have similar code to find the MMU descriptors on 040.

Cheers,

Michael