Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation

[Sandipan Das <sandipan@linux.ibm.com>]

On 03/02/21 3:19 pm, Naveen N. Rao wrote:
> [...]
> 
> Wouldn't it be easier to just do the below at the end? Or, am I missing something?
> 
> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
> index ede093e9623472..a2d726d2a5e9d1 100644
> --- a/arch/powerpc/lib/sstep.c
> +++ b/arch/powerpc/lib/sstep.c
> @@ -2980,6 +2980,10 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>         }
>  #endif /* CONFIG_VSX */
> 
> +       if (GETTYPE(op->type) == LOAD && (op->type & UPDATE) &&
> +                       (ra == 0 || ra == rd))
> +               goto unknown_opcode;
> +
>         return 0;
> 
>   logical_done:
> 

Thanks that's much cleaner! We might need something similar for
the FP load/store and update instructions where an instruction is
invalid if RA is 0. I'll send a new revision with these changes.

- Sandipan