Re: [PATCH 02/15] powerpc/cell: Move data segment faulting code out of cell platform

Jeremy Kerr
2014-09-18T10:27:27Z

Hi Mikey & Ian,

> __spu_trap_data_seg() currently contains code to determine the VSID and ESID
> required for a particular EA and mm struct.
>
> This code is generically useful for other co-processors. This moves the code
> of the cell platform so it can be used by other powerpc code.

OK, nice.

> +
> +int copro_data_segment(struct mm_struct *mm, u64 ea, u64 *esid, u64 *vsid)
> +{
> + int psize, ssize;
> +
> + *esid = (ea & ESID_MASK) | SLB_ESID_V;
> +
> + switch (REGION_ID(ea)) {
> + case USER_REGION_ID:
> + pr_devel("copro_data_segment: 0x%llx -- USER_REGION_ID\n", ea);
> +#ifdef CONFIG_PPC_MM_SLICES
> + psize = get_slice_psize(mm, ea);
> +#else
> + psize = mm->context.user_psize;
> +#endif
> + ssize = user_segment_size(ea);
> + *vsid = (get_vsid(mm->context.id, ea, ssize)
> + << slb_vsid_shift(ssize)) | SLB_VSID_USER
> + | (ssize == MMU_SEGSIZE_1T ? SLB_VSID_B_1T : 0);
> + break;
> + case VMALLOC_REGION_ID:
> + pr_devel("copro_data_segment: 0x%llx -- VMALLOC_REGION_ID\n", ea);
> + if (ea < VMALLOC_END)
> + psize = mmu_vmalloc_psize;
> + else
> + psize = mmu_io_psize;
> + *vsid = (get_kernel_vsid(ea, mmu_kernel_ssize)
> + << SLB_VSID_SHIFT) | SLB_VSID_KERNEL
> + | (mmu_kernel_ssize == MMU_SEGSIZE_1T ? SLB_VSID_B_1T : 0);
> + break;
> + case KERNEL_REGION_ID:
> + pr_devel("copro_data_segment: 0x%llx -- KERNEL_REGION_ID\n", ea);
> + psize = mmu_linear_psize;
> + *vsid = (get_kernel_vsid(ea, mmu_kernel_ssize)
> + << SLB_VSID_SHIFT) | SLB_VSID_KERNEL
> + | (mmu_kernel_ssize == MMU_SEGSIZE_1T ? SLB_VSID_B_1T : 0);
> + break;
> + default:
> + /* Future: support kernel segments so that drivers can use the
> + * CoProcessors */
> + pr_debug("invalid region access at %016llx\n", ea);
> + return 1;
> + }
> + *vsid |= mmu_psize_defs[psize].sllp;

A bit of a nitpick, but how about you remove the repeated:

| (<size> == MMU_SEGSIZE_1T ? SLB_VSID_B_1T : 0)

then set ssize in each of the switch cases (like we do with psize), and
or-in the VSID_B_1T bit at the end:

*vsid |= mmu_psize_defs[psize].sllp
| (ssize == MMU_SEGSIZE_1T ? SLB_VSID_B_1T : 0);

Otherwise, looks good to me.

Cheers,

Jeremy