ppc64: SPARSEMEM_VMEMMAP support

Enable virtual memmap support for SPARSEMEM on PPC64 systems.  Slice a 16th
off the end of the linear mapping space and use that to hold the vmemmap.
Uses the same size mapping as uses in the linear 1:1 kernel mapping.

[pbadari@gmail.com: fix warning]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 037664d496d7dffb72c78f54c47be83d130bb628..5e001ad588a7d385ea5f916ccd32b72c92ed93fe 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -295,6 +295,7 @@ config ARCH_FLATMEM_ENABLE
 config ARCH_SPARSEMEM_ENABLE
        def_bool y
        depends on PPC64
+       select SPARSEMEM_VMEMMAP_ENABLE
 
 config ARCH_SPARSEMEM_DEFAULT
        def_bool y

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index fa90f6561b9f8fcce44f6f0377c66e02228810db..29ed495444f5e109e477defddd0dee704397506e 100644 (file)
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -183,3 +183,70 @@ void pgtable_cache_init(void)
                                                     zero_ctor);
        }
 }
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+/*
+ * Given an address within the vmemmap, determine the pfn of the page that
+ * represents the start of the section it is within.  Note that we have to
+ * do this by hand as the proffered address may not be correctly aligned.
+ * Subtraction of non-aligned pointers produces undefined results.
+ */
+unsigned long __meminit vmemmap_section_start(unsigned long page)
+{
+       unsigned long offset = page - ((unsigned long)(vmemmap));
+
+       /* Return the pfn of the start of the section. */
+       return (offset / sizeof(struct page)) & PAGE_SECTION_MASK;
+}
+
+/*
+ * Check if this vmemmap page is already initialised.  If any section
+ * which overlaps this vmemmap page is initialised then this page is
+ * initialised already.
+ */
+int __meminit vmemmap_populated(unsigned long start, int page_size)
+{
+       unsigned long end = start + page_size;
+
+       for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
+               if (pfn_valid(vmemmap_section_start(start)))
+                       return 1;
+
+       return 0;
+}
+
+int __meminit vmemmap_populate(struct page *start_page,
+                                       unsigned long nr_pages, int node)
+{
+       unsigned long mode_rw;
+       unsigned long start = (unsigned long)start_page;
+       unsigned long end = (unsigned long)(start_page + nr_pages);
+       unsigned long page_size = 1 << mmu_psize_defs[mmu_linear_psize].shift;
+
+       mode_rw = _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_COHERENT | PP_RWXX;
+
+       /* Align to the page size of the linear mapping. */
+       start = _ALIGN_DOWN(start, page_size);
+
+       for (; start < end; start += page_size) {
+               int mapped;
+               void *p;
+
+               if (vmemmap_populated(start, page_size))
+                       continue;
+
+               p = vmemmap_alloc_block(page_size, node);
+               if (!p)
+                       return -ENOMEM;
+
+               printk(KERN_WARNING "vmemmap %08lx allocated at %p, "
+                                       "physical %p.\n", start, p, __pa(p));
+
+               mapped = htab_bolt_mapping(start, start + page_size,
+                                       __pa(p), mode_rw, mmu_linear_psize);
+               BUG_ON(mapped < 0);
+       }
+
+       return 0;
+}
+#endif

diff --git a/include/asm-powerpc/pgtable-ppc64.h b/include/asm-powerpc/pgtable-ppc64.h
index 300f9a199bf29d95e147569e354e740bd6f43d58..dd4c26dc57d2727d533c19fef3f9ad4224ccf737 100644 (file)
--- a/include/asm-powerpc/pgtable-ppc64.h
+++ b/include/asm-powerpc/pgtable-ppc64.h
@@ -67,6 +67,14 @@
 #define KERNEL_REGION_ID       (REGION_ID(PAGE_OFFSET))
 #define USER_REGION_ID         (0UL)
 
+/*
+ * Defines the address of the vmemap area, in the top 16th of the
+ * kernel region.
+ */
+#define VMEMMAP_BASE (ASM_CONST(CONFIG_KERNEL_START) + \
+                                       (0xfUL << (REGION_SHIFT - 4)))
+#define vmemmap ((struct page *)VMEMMAP_BASE)
+
 /*
  * Common bits in a linux-style PTE.  These match the bits in the
  * (hardware-defined) PowerPC PTE as closely as possible. Additional