RFC: ESR_I/DLK processing

[Jimi Xenidis]

arch/powerpc/kernel/head_fsl_booke.S has the following code:
> 	/* Data Storage Interrupt */
> 	START_EXCEPTION(DataStorage)
> 	NORMAL_EXCEPTION_PROLOG
> 	mfspr	r5,SPRN_ESR		/* Grab the ESR, save it, pass arg3 */
> 	stw	r5,_ESR(r11)
> 	mfspr	r4,SPRN_DEAR		/* Grab the DEAR, save it, pass arg2 */
> 	andis.	r10,r5,(ESR_ILK|ESR_DLK)@h
> 	bne	1f
> 	EXC_XFER_EE_LITE(0x0300, handle_page_fault)
> 1:
> 	addi	r3,r1,STACK_FRAME_OVERHEAD
> 	EXC_XFER_EE_LITE(0x0300, CacheLockingException)


I need something similar for A2 (and all book3e) and was wondering, why this isn't just:

> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 88abe70..8451822 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -159,6 +159,14 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
>  	}
>  #endif
>  
> +#ifdef CONFIG_PPC_BOOK3E
> +	if (error_code & (ESR_DLK|ESR_ILK)) {
> +		/* detect that this is a privileged op and SIGILL */
> +		_exception(SIGILL, regs, ILL_PRVOPC, regs->nip);
> +		return 0;
> +	}
> +#endif
> +
>  	if (notify_page_fault(regs))
>  		return 0;

Its not like this need to be fast or anything.
I'd be happy to submit a patch that adds to fault.c and removed the I/DLK processing from head_fsl_booke.S

Thoughts?
-jx