Handling of alignment exceptions of load/store multiples

[Paul Mackerras]

Becky Bruce writes:

> I'm currently in the process of merging align.c into 
> arch/powerpc/kernel.  I noticed that there's a difference in the 
> handling of alignment exceptions involving ld/st string instructions 
> and ld/st multiple instructions between the 2 architectures right now.  
> The 32-bit code does some handling of these, while the 64-bit version 
> currently just bails out.
> 
> Should I try to adopt a handling model for these in the merged tree 
> like the 32-bit code, or is there a reason behind not attempting to 
> handle these on the 64-bit side that I'm not aware of?

I think we might as well include the code for handling them, since we
have it.  On the 64-bit side, I think they left that stuff out because
(AFAICT) all the 64-bit cpus handle misaligned ld/st string in
hardware, and misaligned ld/st multiple are deprecated by the
architecture (implementations are allowed to produce boundedly
undefined results).

Regards,
Paul.