Re: [PATCH RFC 1/2] m68k: Don't deliver signals except at instruction boundary

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Andreas, Finn,

On 3/05/23 04:51, Andreas Schwab wrote:
> On Mai 02 2023, Finn Thain wrote:
>
>> From: Andreas Schwab <schwab@linux-m68k.org>
>>
>> Signal delivery should only happen at insn boundaries, but due to the
>> way the 030 handles return from bus error exceptions (the insn is resumed,
>> not restarted like on the 040/060) the kernel may do it in the middle of
>> the faulting insn.
> I don't think this will work properly when the address cannot be
> resolved.  The bus error exception will just be raised again
> immediately.

Seems certain, even though we haven't observed that in testing yet 
(haven't designed the test case for that specifically, mind you).

The (slighty hairy) sole solution to this (that I can see) would be to 
only skip signal delivery on the condition that bus_error030 was able to 
correct the bus fault.

In any other case bus_error030 will raise SIGKILL or SIGSEGV which must 
be delivered right away.

Can we infer that from the state of the fault frame after bus_error030, 
or do we have to modify bus_error030 to return success/error codes?

Cheers,

     Michael