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, 5 insertions, 2 deletions

diff --git a/arch/tile/include/asm/pgalloc.h b/arch/tile/include/asm/pgalloc.h
index cf52791a550..e919c0bdc22 100644
--- a/arch/tile/include/asm/pgalloc.h
+++ b/arch/tile/include/asm/pgalloc.h
@@ -41,9 +41,9 @@
 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
 #ifdef CONFIG_64BIT
-	set_pte_order(pmdp, pmd, L2_USER_PGTABLE_ORDER);
+	set_pte(pmdp, pmd);
 #else
-	set_pte_order(&pmdp->pud.pgd, pmd.pud.pgd, L2_USER_PGTABLE_ORDER);
+	set_pte(&pmdp->pud.pgd, pmd.pud.pgd);
 #endif
 }
 
@@ -100,6 +100,9 @@ pte_t *get_prealloc_pte(unsigned long pfn);
 /* During init, we can shatter kernel huge pages if needed. */
 void shatter_pmd(pmd_t *pmd);
 
+/* After init, a more complex technique is required. */
+void shatter_huge_page(unsigned long addr);
+
 #ifdef __tilegx__
 /* We share a single page allocator for both L1 and L2 page tables. */
 #if HV_L1_SIZE != HV_L2_SIZE