powerpc/mm: Add support for SPARSEMEM_VMEMMAP on 64-bit Book3E

The base TLB support didn't include support for SPARSEMEM_VMEMMAP, though
we did carve out some virtual space for it, the necessary support code
wasn't there. This implements it by using 16M pages for now, though the
page size could easily be changed at runtime if necessary.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 48 insertions, 7 deletions

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 68a821add28d..31582329cd67 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -205,6 +205,47 @@ static int __meminit vmemmap_populated(unsigned long start, int page_size)
         return 0;
 }
 
+/* On hash-based CPUs, the vmemmap is bolted in the hash table.
+ *
+ * On Book3E CPUs, the vmemmap is currently mapped in the top half of
+ * the vmalloc space using normal page tables, though the size of
+ * pages encoded in the PTEs can be different
+ */
+
+#ifdef CONFIG_PPC_BOOK3E
+static void __meminit vmemmap_create_mapping(unsigned long start,
+                                             unsigned long page_size,
+                                             unsigned long phys)
+{
+        /* Create a PTE encoding without page size */
+        unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
+                _PAGE_KERNEL_RW;
+
+        /* PTEs only contain page size encodings up to 32M */
+        BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);
+
+        /* Encode the size in the PTE */
+        flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;
+
+        /* For each PTE for that area, map things. Note that we don't
+         * increment phys because all PTEs are of the large size and
+         * thus must have the low bits clear
+         */
+        for (i = 0; i < page_size; i += PAGE_SIZE)
+                BUG_ON(map_kernel_page(start + i, phys, flags));
+}
+#else /* CONFIG_PPC_BOOK3E */
+static void __meminit vmemmap_create_mapping(unsigned long start,
+                                             unsigned long page_size,
+                                             unsigned long phys)
+{
+        int  mapped = htab_bolt_mapping(start, start + page_size, phys,
+                                        PAGE_KERNEL, mmu_vmemmap_psize,
+                                        mmu_kernel_ssize);
+        BUG_ON(mapped < 0);
+}
+#endif /* CONFIG_PPC_BOOK3E */
+
 int __meminit vmemmap_populate(struct page *start_page,
                                unsigned long nr_pages, int node)
 {
@@ -215,8 +256,11 @@ int __meminit vmemmap_populate(struct page *start_page,
         /* Align to the page size of the linear mapping. */
         start = _ALIGN_DOWN(start, page_size);
 
+        pr_debug("vmemmap_populate page %p, %ld pages, node %d\n",
+                 start_page, nr_pages, node);
+        pr_debug(" -> map %lx..%lx\n", start, end);
+
         for (; start < end; start += page_size) {
-                int mapped;
                 void *p;
 
                 if (vmemmap_populated(start, page_size))
@@ -226,13 +270,10 @@ int __meminit vmemmap_populate(struct page *start_page,
                 if (!p)
                         return -ENOMEM;
 
-                pr_debug("vmemmap %08lx allocated at %p, physical %08lx.\n",
-                        start, p, __pa(p));
+                pr_debug("      * %016lx..%016lx allocated at %p\n",
+                         start, start + page_size, p);
 
-                mapped = htab_bolt_mapping(start, start + page_size, __pa(p),
-                                           pgprot_val(PAGE_KERNEL),
-                                           mmu_vmemmap_psize, mmu_kernel_ssize);
-                BUG_ON(mapped < 0);
+                vmemmap_create_mapping(start, page_size, __pa(p));
         }
 
         return 0;