arch/tile: support 4KB page size as well as 64KB

The Tilera architecture traditionally supports 64KB page sizes
to improve TLB utilization and improve performance when the
hardware is being used primarily to run a single application.

For more generic server scenarios, it can be beneficial to run
with 4KB page sizes, so this commit allows that to be specified
(by modifying the arch/tile/include/hv/pagesize.h header).

As part of this change, we also re-worked the PTE management
slightly so that PTE writes all go through a __set_pte() function
where we can do some additional validation.  The set_pte_order()
function was eliminated since the "order" argument wasn't being used.

One bug uncovered was in the PCI DMA code, which wasn't properly
flushing the specified range.  This was benign with 64KB pages,
but with 4KB pages we were getting some larger flushes wrong.

The per-cpu memory reservation code also needed updating to
conform with the newer percpu stuff; before it always chose 64KB,
and that was always correct, but with 4KB granularity we now have
to pay closer attention and reserve the amount of memory that will
be requested when the percpu code starts allocating.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 19 insertions, 19 deletions

diff --git a/arch/tile/kernel/pci-dma.c b/arch/tile/kernel/pci-dma.c
index 5ad5e13b0fa..658752b2835 100644
--- a/arch/tile/kernel/pci-dma.c
+++ b/arch/tile/kernel/pci-dma.c
@@ -86,6 +86,21 @@ EXPORT_SYMBOL(dma_free_coherent);
  * can count on nothing having been touched.
  */
 
+/* Flush a PA range from cache page by page. */
+static void __dma_map_pa_range(dma_addr_t dma_addr, size_t size)
+{
+	struct page *page = pfn_to_page(PFN_DOWN(dma_addr));
+	size_t bytesleft = PAGE_SIZE - (dma_addr & (PAGE_SIZE - 1));
+
+	while ((ssize_t)size > 0) {
+		/* Flush the page. */
+		homecache_flush_cache(page++, 0);
+
+		/* Figure out if we need to continue on the next page. */
+		size -= bytesleft;
+		bytesleft = PAGE_SIZE;
+	}
+}
 
 /*
  * dma_map_single can be passed any memory address, and there appear
@@ -97,26 +112,12 @@ EXPORT_SYMBOL(dma_free_coherent);
 dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
 	       enum dma_data_direction direction)
 {
-	struct page *page;
-	dma_addr_t dma_addr;
-	int thispage;
+	dma_addr_t dma_addr = __pa(ptr);
 
 	BUG_ON(!valid_dma_direction(direction));
 	WARN_ON(size == 0);
 
-	dma_addr = __pa(ptr);
-
-	/* We might have been handed a buffer that wraps a page boundary */
-	while ((int)size > 0) {
-		/* The amount to flush that's on this page */
-		thispage = PAGE_SIZE - ((unsigned long)ptr & (PAGE_SIZE - 1));
-		thispage = min((int)thispage, (int)size);
-		/* Is this valid for any page we could be handed? */
-		page = pfn_to_page(kaddr_to_pfn(ptr));
-		homecache_flush_cache(page, 0);
-		ptr += thispage;
-		size -= thispage;
-	}
+	__dma_map_pa_range(dma_addr, size);
 
 	return dma_addr;
 }
@@ -140,10 +141,8 @@ int dma_map_sg(struct device *dev, struct scatterlist *sglist, int nents,
 	WARN_ON(nents == 0 || sglist->length == 0);
 
 	for_each_sg(sglist, sg, nents, i) {
-		struct page *page;
 		sg->dma_address = sg_phys(sg);
-		page = pfn_to_page(sg->dma_address >> PAGE_SHIFT);
-		homecache_flush_cache(page, 0);
+		__dma_map_pa_range(sg->dma_address, sg->length);
 	}
 
 	return nents;
@@ -163,6 +162,7 @@ dma_addr_t dma_map_page(struct device *dev, struct page *page,
 {
 	BUG_ON(!valid_dma_direction(direction));
 
+	BUG_ON(offset + size > PAGE_SIZE);
 	homecache_flush_cache(page, 0);
 
 	return page_to_pa(page) + offset;