powerpc: Hugetlb for BookE

Enable hugepages on Freescale BookE processors.  This allows the kernel to
use huge TLB entries to map pages, which can greatly reduce the number of
TLB misses and the amount of TLB thrashing experienced by applications with
large memory footprints.  Care should be taken when using this on FSL
processors, as the number of large TLB entries supported by the core is low
(16-64) on current processors.

The supported set of hugepage sizes include 4m, 16m, 64m, 256m, and 1g.
Page sizes larger than the max zone size are called "gigantic" pages and
must be allocated on the command line (and cannot be deallocated).

This is currently only fully implemented for Freescale 32-bit BookE
processors, but there is some infrastructure in the code for
64-bit BooKE.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 10 insertions, 8 deletions

diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 698b3063868..f0145522cfb 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -175,14 +175,16 @@ extern u64 ppc64_rma_size;
 #define MMU_PAGE_64K_AP	3	/* "Admixed pages" (hash64 only) */
 #define MMU_PAGE_256K	4
 #define MMU_PAGE_1M	5
-#define MMU_PAGE_8M	6
-#define MMU_PAGE_16M	7
-#define MMU_PAGE_256M	8
-#define MMU_PAGE_1G	9
-#define MMU_PAGE_16G	10
-#define MMU_PAGE_64G	11
-#define MMU_PAGE_COUNT	12
-
+#define MMU_PAGE_4M	6
+#define MMU_PAGE_8M	7
+#define MMU_PAGE_16M	8
+#define MMU_PAGE_64M	9
+#define MMU_PAGE_256M	10
+#define MMU_PAGE_1G	11
+#define MMU_PAGE_16G	12
+#define MMU_PAGE_64G	13
+
+#define MMU_PAGE_COUNT	14
 
 #if defined(CONFIG_PPC_STD_MMU_64)
 /* 64-bit classic hash table MMU */