[PATCH v2 06/17] ARM: dma-mapping: fix for speculative accesses

[saeed bishara]

> +       if (dir == DMA_FROM_DEVICE) {
> +               outer_inv_range(paddr, paddr + size);
> +               dmac_inv_range(kaddr, kaddr + size);
it's not clear why outer cache invalidated before inner cache, and, I
think that it may be incorrect, how can you be sure that a dirty line
that is in inner cache can't be moved down to outer cache?
> +       } else {
> +               dmac_clean_range(kaddr, kaddr + size);
> +               outer_clean_range(paddr, paddr + size);
>        }
> +}
> +EXPORT_SYMBOL(___dma_single_cpu_to_dev);
>
> -       inner_op(start, start + size);
> -       outer_op(__pa(start), __pa(start) + size);
> +void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
> +       enum dma_data_direction dir)
> +{
> +       BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
> +
> +       /* don't bother invalidating if DMA to device */
> +       if (dir != DMA_TO_DEVICE) {
> +               unsigned long paddr = __pa(kaddr);
> +               outer_inv_range(paddr, paddr + size);
> +               dmac_inv_range(kaddr, kaddr + size);
> +       }
that code implies that cache invalidate will be applied also for CPU's
that doesn't suffer from speculative prefetch issue, right?
>  }
> -EXPORT_SYMBOL(dma_cache_maint);
> +EXPORT_SYMBOL(___dma_single_dev_to_cpu);
>
>  static void dma_cache_maint_contiguous(struct page *page, unsigned long offset,
> -                                      size_t size, int direction)
> +                      size_t size, void (*op)(const void *, const void *))
>  {
>        void *vaddr;
> -       unsigned long paddr;
> -       void (*inner_op)(const void *, const void *);
> -       void (*outer_op)(unsigned long, unsigned long);
> -
> -       switch (direction) {
> -       case DMA_FROM_DEVICE:           /* invalidate only */
> -               inner_op = dmac_inv_range;
> -               outer_op = outer_inv_range;
> -               break;
> -       case DMA_TO_DEVICE:             /* writeback only */
> -               inner_op = dmac_clean_range;
> -               outer_op = outer_clean_range;
> -               break;
> -       case DMA_BIDIRECTIONAL:         /* writeback and invalidate */
> -               inner_op = dmac_flush_range;
> -               outer_op = outer_flush_range;
> -               break;
> -       default:
> -               BUG();
> -       }
>
>        if (!PageHighMem(page)) {
>                vaddr = page_address(page) + offset;
> -               inner_op(vaddr, vaddr + size);
> +               op(vaddr, vaddr + size);
>        } else {
>                vaddr = kmap_high_get(page);
>                if (vaddr) {
>                        vaddr += offset;
> -                       inner_op(vaddr, vaddr + size);
> +                       op(vaddr, vaddr + size);
>                        kunmap_high(page);
>                }
>        }
> -
> -       paddr = page_to_phys(page) + offset;
> -       outer_op(paddr, paddr + size);
>  }
>
> -void dma_cache_maint_page(struct page *page, unsigned long offset,
> -                         size_t size, int dir)
> +void __dma_cache_maint_page(struct page *page, unsigned long offset,
> +       size_t size, void (*op)(const void *, const void *))
>  {
>        /*
>         * A single sg entry may refer to multiple physically contiguous
> @@ -628,13 +608,40 @@ void dma_cache_maint_page(struct page *page, unsigned long offset,
>                        }
>                        len = PAGE_SIZE - offset;
>                }
> -               dma_cache_maint_contiguous(page, offset, len, dir);
> +               dma_cache_maint_contiguous(page, offset, len, op);
>                offset = 0;
>                page++;
>                left -= len;
>        } while (left);
>  }
> -EXPORT_SYMBOL(dma_cache_maint_page);
> +
> +void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
> +       size_t size, enum dma_data_direction dir)
> +{
> +       unsigned long paddr = page_to_phys(page) + offset;
> +
> +       if (dir == DMA_FROM_DEVICE) {
> +               outer_inv_range(paddr, paddr + size);
> +               __dma_cache_maint_page(page, off, size, dmac_inv_range);
> +       } else {
> +               __dma_cache_maint_page(page, off, size, dmac_clean_range);
> +               outer_clean_range(paddr, paddr + size);
> +       }
> +}
> +EXPORT_SYMBOL(___dma_page_cpu_to_dev);
> +
> +void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
> +       size_t size, enum dma_data_direction dir)
> +{
> +       unsigned long paddr = page_to_phys(page) + offset;
> +
> +       /* don't bother invalidating if DMA to device */
> +       if (dir != DMA_TO_DEVICE) {
> +               outer_inv_range(paddr, paddr + size);
> +               __dma_cache_maint_page(page, off, size, dmac_inv_range);
> +       }
> +}
> +EXPORT_SYMBOL(___dma_page_dev_to_cpu);
>
>  /**
>  * dma_map_sg - map a set of SG buffers for streaming mode DMA
> --
> 1.6.2.5
>
>
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