On Mon, Oct 13, 2008 at 04:18:04PM +0100, Maciej W. Rozycki wrote:
> /*
> + * To avoid the BCM1250 M3 erratum check whether EntryHi is consistent
> + * with BadVAddr and return for the exception to retrigger if not.
> + */
> +static void __cpuinit build_bcm1250_m3_war(u32 **p, struct uasm_reloc **r)
> +{
> + uasm_i_dmfc0(p, K0, C0_BADVADDR);
> + uasm_i_dmfc0(p, K1, C0_ENTRYHI);
> + uasm_i_xor(p, K0, K0, K1);
> + uasm_i_dsll(p, K1, K0, 24);
> + uasm_i_dsrl32(p, K1, K1, (24 + PAGE_SHIFT + 1) - 32);
> + uasm_i_dsrl32(p, K0, K0, 30);
> + uasm_i_or(p, K0, K0, K1);
> + uasm_il_bnez(p, r, K0, label_leave);
The workaround is beginning to be relativly expensive. We're investing 8
instructions extra only to verify that the content of c0_entryhi is
correct. I haven't tried yet but me seems by avoiding the use of c0_context
entirely relying only on badvaddr we may be able to get away cheaper.
Btw, adding linux-mips to the cc list. This really should be public.
Ralf
