powerpc: New hugepage directory format

Change the hugepage directory format so that we can have leaf ptes directly
at page directory avoiding the allocation of hugepage directory.

With the new table format we have 3 cases for pgds and pmds:
(1) invalid (all zeroes)
(2) pointer to next table, as normal; bottom 6 bits == 0
(4) hugepd pointer, bottom two bits == 00, next 4 bits indicate size of table

Instead of storing shift value in hugepd pointer we use mmu_psize_def index
so that we can fit all the supported hugepage size in 4 bits

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index f072e974f8a2..652719ccd2e9 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -249,6 +249,7 @@ extern long long virt_phys_offset;
 #define is_kernel_addr(x)	((x) >= PAGE_OFFSET)
 #endif
 
+#ifndef CONFIG_PPC_BOOK3S_64
 /*
  * Use the top bit of the higher-level page table entries to indicate whether
  * the entries we point to contain hugepages.  This works because we know that
@@ -260,6 +261,7 @@ extern long long virt_phys_offset;
 #else
 #define PD_HUGE 0x80000000
 #endif
+#endif /* CONFIG_PPC_BOOK3S_64 */
 
 /*
  * Some number of bits at the level of the page table that points to
@@ -354,10 +356,21 @@ typedef unsigned long pgprot_t;
 typedef struct { signed long pd; } hugepd_t;
 
 #ifdef CONFIG_HUGETLB_PAGE
+#ifdef CONFIG_PPC_BOOK3S_64
+static inline int hugepd_ok(hugepd_t hpd)
+{
+	/*
+	 * hugepd pointer, bottom two bits == 00 and next 4 bits
+	 * indicate size of table
+	 */
+	return (((hpd.pd & 0x3) == 0x0) && ((hpd.pd & HUGEPD_SHIFT_MASK) != 0));
+}
+#else
 static inline int hugepd_ok(hugepd_t hpd)
 {
 	return (hpd.pd > 0);
 }
+#endif
 
 #define is_hugepd(pdep)               (hugepd_ok(*((hugepd_t *)(pdep))))
 #else /* CONFIG_HUGETLB_PAGE */