Re: [PATCH 3/3] powerpc: Correctly context switch DSCR on POWER8

[Stephen Rothwell <sfr@canb.auug.org.au>]

[-- Attachment #1: Type: text/plain, Size: 2032 bytes --]

[This time from a good email address :-)]

Hi Mikey,

On Mon,  5 Aug 2013 17:28:06 +1000 Michael Neuling
<mikey@neuling.org> wrote:
>
> +++ b/arch/powerpc/kernel/traps.c
> @@ -1296,43 +1294,56 @@ void vsx_unavailable_exception(struct pt_regs *regs)
>  	die("Unrecoverable VSX Unavailable Exception", regs, SIGABRT);
>  }
>  
> +#ifdef CONFIG_PPC64
>  void facility_unavailable_exception(struct pt_regs *regs)
>  {
>  	static char *facility_strings[] = {
> -		"FPU",
> -		"VMX/VSX",
> -		"DSCR",
> -		"PMU SPRs",
> -		"BHRB",
> -		"TM",
> -		"AT",
> -		"EBB",
> -		"TAR",
> +		[FSCR_FP_LG] = "FPU",
> +		[FSCR_VECVSX_LG] = "VMX/VSX",
> +		[FSCR_DSCR_LG] = "DSCR",
> +		[FSCR_PM_LG] = "PMU SPRs",
> +		[FSCR_BHRB_LG] = "BHRB",
> +		[FSCR_TM_LG] = "TM",
> +		[FSCR_EBB_LG] = "EBB",
> +		[FSCR_TAR_LG] = "TAR",

I assume that you intentionally dropped "AT".

>  	};
> -	char *facility, *prefix;
> +	char *facility;
>  	u64 value;
> +	u8 status;
> +	bool hv;
>  
>  	if (regs->trap == 0xf60) {
>  		value = mfspr(SPRN_FSCR);
> -		prefix = "";
> +		hv = false;
>  	} else {
>  		value = mfspr(SPRN_HFSCR);
> -		prefix = "Hypervisor ";
> +		hv = true;
>  	}

Maybe:
	hv = regs->trap == 0xf60;
	if (hv)
		value = mfspr(SPRN_HFSCR);
	else
		value = mfspr(SPRN_HFSCR);
or
	value = mfspr(hv ? SPRN_HFSCR : SPRN_HFSCR);

> -	value = value >> 56;
> +	status = value >> 56;
> +
> +	if (status < ARRAY_SIZE(facility_strings))
> +		facility = facility_strings[status];
> +	else
> +		facility = "unknown";

For entries in the array that are not set, this will give facility ==
NULL.  Is that what you intended?

>  	pr_err("%sFacility '%s' unavailable, exception at 0x%lx, MSR=%lx\n",
> -		prefix, facility, regs->nip, regs->msr);
> +	       hv ? "Hypervisor ":"", facility, regs->nip, regs->msr);

... and this may attempt to print a NULL pointer with %s.  Also please
put spaces around the : .

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

[-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]