[SPARC64]: Temporarily remove IOMMU merging code.

Changeset fde6a3c82d67f592eb587be4d12222b0ae6d4321 ("iommu sg merging:
sparc64: make iommu respect the segment size limits") broke sparc64
because whilst it added the segment limiting code to the first pass of
SG mapping (in prepare_sg()) it did not add matching code to the
second pass handling (in fill_sg())

As a result the two passes disagree where the segment boundaries
should be, resulting in OOPSes, DMA corruption, and corrupted
superblocks.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 116 deletions

diff --git a/arch/sparc64/kernel/iommu.c b/arch/sparc64/kernel/iommu.c
index 4b9115a4d92e..5623a4d59dff 100644
--- a/arch/sparc64/kernel/iommu.c
+++ b/arch/sparc64/kernel/iommu.c
@@ -472,94 +472,15 @@ static void dma_4u_unmap_single(struct device *dev, dma_addr_t bus_addr,
         spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
-#define SG_ENT_PHYS_ADDRESS(SG) (__pa(sg_virt((SG))))
-
-static void fill_sg(iopte_t *iopte, struct scatterlist *sg,
-                    int nused, int nelems,
-                    unsigned long iopte_protection)
-{
-        struct scatterlist *dma_sg = sg;
-        int i;
-
-        for (i = 0; i < nused; i++) {
-                unsigned long pteval = ~0UL;
-                u32 dma_npages;
-
-                dma_npages = ((dma_sg->dma_address & (IO_PAGE_SIZE - 1UL)) +
-                              dma_sg->dma_length +
-                              ((IO_PAGE_SIZE - 1UL))) >> IO_PAGE_SHIFT;
-                do {
-                        unsigned long offset;
-                        signed int len;
-
-                        /* If we are here, we know we have at least one
-                         * more page to map.  So walk forward until we
-                         * hit a page crossing, and begin creating new
-                         * mappings from that spot.
-                         */
-                        for (;;) {
-                                unsigned long tmp;
-
-                                tmp = SG_ENT_PHYS_ADDRESS(sg);
-                                len = sg->length;
-                                if (((tmp ^ pteval) >> IO_PAGE_SHIFT) != 0UL) {
-                                        pteval = tmp & IO_PAGE_MASK;
-                                        offset = tmp & (IO_PAGE_SIZE - 1UL);
-                                        break;
-                                }
-                                if (((tmp ^ (tmp + len - 1UL)) >> IO_PAGE_SHIFT) != 0UL) {
-                                        pteval = (tmp + IO_PAGE_SIZE) & IO_PAGE_MASK;
-                                        offset = 0UL;
-                                        len -= (IO_PAGE_SIZE - (tmp & (IO_PAGE_SIZE - 1UL)));
-                                        break;
-                                }
-                                sg = sg_next(sg);
-                                nelems--;
-                        }
-
-                        pteval = iopte_protection | (pteval & IOPTE_PAGE);
-                        while (len > 0) {
-                                *iopte++ = __iopte(pteval);
-                                pteval += IO_PAGE_SIZE;
-                                len -= (IO_PAGE_SIZE - offset);
-                                offset = 0;
-                                dma_npages--;
-                        }
-
-                        pteval = (pteval & IOPTE_PAGE) + len;
-                        sg = sg_next(sg);
-                        nelems--;
-
-                        /* Skip over any tail mappings we've fully mapped,
-                         * adjusting pteval along the way.  Stop when we
-                         * detect a page crossing event.
-                         */
-                        while (nelems &&
-                               (pteval << (64 - IO_PAGE_SHIFT)) != 0UL &&
-                               (pteval == SG_ENT_PHYS_ADDRESS(sg)) &&
-                               ((pteval ^
-                                 (SG_ENT_PHYS_ADDRESS(sg) + sg->length - 1UL)) >> IO_PAGE_SHIFT) == 0UL) {
-                                pteval += sg->length;
-                                sg = sg_next(sg);
-                                nelems--;
-                        }
-                        if ((pteval << (64 - IO_PAGE_SHIFT)) == 0UL)
-                                pteval = ~0UL;
-                } while (dma_npages != 0);
-                dma_sg = sg_next(dma_sg);
-        }
-}
-
 static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
                          int nelems, enum dma_data_direction direction)
 {
-        struct iommu *iommu;
+        unsigned long flags, ctx, i, npages, iopte_protection;
+        struct scatterlist *sg;
         struct strbuf *strbuf;
-        unsigned long flags, ctx, npages, iopte_protection;
+        struct iommu *iommu;
         iopte_t *base;
         u32 dma_base;
-        struct scatterlist *sgtmp;
-        int used;
 
         /* Fast path single entry scatterlists. */
         if (nelems == 1) {
@@ -578,11 +499,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
         if (unlikely(direction == DMA_NONE))
                 goto bad_no_ctx;
 
-        /* Step 1: Prepare scatter list. */
-
-        npages = prepare_sg(dev, sglist, nelems);
-
-        /* Step 2: Allocate a cluster and context, if necessary. */
+        npages = calc_npages(sglist, nelems);
 
         spin_lock_irqsave(&iommu->lock, flags);
 
@@ -599,18 +516,6 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
         dma_base = iommu->page_table_map_base +
                 ((base - iommu->page_table) << IO_PAGE_SHIFT);
 
-        /* Step 3: Normalize DMA addresses. */
-        used = nelems;
-
-        sgtmp = sglist;
-        while (used && sgtmp->dma_length) {
-                sgtmp->dma_address += dma_base;
-                sgtmp = sg_next(sgtmp);
-                used--;
-        }
-        used = nelems - used;
-
-        /* Step 4: Create the mappings. */
         if (strbuf->strbuf_enabled)
                 iopte_protection = IOPTE_STREAMING(ctx);
         else
@@ -618,13 +523,27 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
         if (direction != DMA_TO_DEVICE)
                 iopte_protection |= IOPTE_WRITE;
 
-        fill_sg(base, sglist, used, nelems, iopte_protection);
+        for_each_sg(sglist, sg, nelems, i) {
+                unsigned long paddr = SG_ENT_PHYS_ADDRESS(sg);
+                unsigned long slen = sg->length;
+                unsigned long this_npages;
 
-#ifdef VERIFY_SG
-        verify_sglist(sglist, nelems, base, npages);
-#endif
+                this_npages = iommu_num_pages(paddr, slen);
 
-        return used;
+                sg->dma_address = dma_base | (paddr & ~IO_PAGE_MASK);
+                sg->dma_length = slen;
+
+                paddr &= IO_PAGE_MASK;
+                while (this_npages--) {
+                        iopte_val(*base) = iopte_protection | paddr;
+
+                        base++;
+                        paddr += IO_PAGE_SIZE;
+                        dma_base += IO_PAGE_SIZE;
+                }
+        }
+
+        return nelems;
 
 bad:
         iommu_free_ctx(iommu, ctx);
@@ -637,11 +556,10 @@ bad_no_ctx:
 static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,
                             int nelems, enum dma_data_direction direction)
 {
-        struct iommu *iommu;
+        unsigned long flags, ctx, i, npages;
         struct strbuf *strbuf;
+        struct iommu *iommu;
         iopte_t *base;
-        unsigned long flags, ctx, i, npages;
-        struct scatterlist *sg, *sgprv;
         u32 bus_addr;
 
         if (unlikely(direction == DMA_NONE)) {
@@ -654,15 +572,7 @@ static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,
 
         bus_addr = sglist->dma_address & IO_PAGE_MASK;
 
-        sgprv = NULL;
-        for_each_sg(sglist, sg, nelems, i) {
-                if (sg->dma_length == 0)
-                        break;
-                sgprv = sg;
-        }
-
-        npages = (IO_PAGE_ALIGN(sgprv->dma_address + sgprv->dma_length) -
-                  bus_addr) >> IO_PAGE_SHIFT;
+        npages = calc_npages(sglist, nelems);
 
         base = iommu->page_table +
                 ((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);