Subject: Re: [PATCH V5] powerpc/85xx: Add machine check handler to fix PCIe erratum on mpc85xx

From: Scott Wood <[email-masked]>
Date: Wed, 10 Apr 2013 16:51:43 -0500

On 04/08/2013 03:26:54 AM, Jia Hongtao wrote:
> @@ -826,6 +829,124 @@ u64 fsl_pci_immrbar_base(struct pci_controller =20
> *hose)
>  	return 0;
>  }
>=20
> +#ifdef CONFIG_E500
> +
> +#define OP_LWZ  32
> +#define OP_LWZU 33
> +#define OP_LBZ  34
> +#define OP_LBZU 35
> +#define OP_LHZ  40
> +#define OP_LHZU 41
> +#define OP_LHA  42
> +#define OP_LHAU 43

Can you move these to asm/ppc-opcode.h (or possibly =20
asm/ppc-disassemble.h if we don't want to mix the two methods of =20
describing instructions)?

> +static int mcheck_handle_load(struct pt_regs *regs, u32 inst)
> +{
> +	unsigned int rd, ra, d;
> +
> +	rd =3D get_rt(inst);
> +	ra =3D get_ra(inst);
> +	d =3D get_d(inst);
> +
> +	switch (get_op(inst)) {
> +	case OP_LWZ:
> +		regs->gpr[rd] =3D 0xffffffff;
> +		break;
> +
> +	case OP_LWZU:
> +		regs->gpr[rd] =3D 0xffffffff;
> +		regs->gpr[ra] +=3D (s16)d;
> +		break;
> +
> +	case OP_LBZ:
> +		regs->gpr[rd] =3D 0xff;
> +		break;
> +
> +	case OP_LBZU:
> +		regs->gpr[rd] =3D 0xff;
> +		regs->gpr[ra] +=3D (s16)d;
> +		break;
> +
> +	case OP_LHZ:
> +		regs->gpr[rd] =3D 0xffff;
> +		break;
> +
> +	case OP_LHZU:
> +		regs->gpr[rd] =3D 0xffff;
> +		regs->gpr[ra] +=3D (s16)d;
> +		break;
> +
> +	case OP_LHA:
> +		regs->gpr[rd] =3D 0xffff;
> +		break;
> +
> +	case OP_LHAU:
> +		regs->gpr[rd] =3D 0xffff;
> +		regs->gpr[ra] +=3D (s16)d;
> +		break;

The X and (especially for PCI) BRX versions are important -- probably =20
more so than the U versions.  I doubt we need the A variant.

If you do support the A variant, why are you not sign-extending the =20
value?

Is this erratum present on any 64-bit chips?

-Scott=