powerpc/8xx: Implement support of hugepages

8xx uses a two level page table with two different linux page size
support (4k and 16k). 8xx also support two different hugepage sizes
512k and 8M. In order to support them on linux we define two different
page table layout.

The size of pages is in the PGD entry, using PS field (bits 28-29):
00 : Small pages (4k or 16k)
01 : 512k pages
10 : reserved
11 : 8M pages

For 512K hugepage size a pgd entry have the below format
[<hugepte address >0101] . The hugepte table allocated will contain 8
entries pointing to 512K huge pte in 4k pages mode and 64 entries in
16k pages mode.

For 8M in 16k mode, a pgd entry have the below format
[<hugepte address >1101] . The hugepte table allocated will contain 8
entries pointing to 8M huge pte.

For 8M in 4k mode, multiple pgd entries point to the same hugepte
address and pgd entry will have the below format
[<hugepte address>1101]. The hugepte table allocated will only have one
entry.

For the time being, we do not support CPU15 ERRATA when HUGETLB is
selected

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> (v3, for the generic bits)
Signed-off-by: Scott Wood <oss@buserror.net>

1 files changed, 19 insertions, 10 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 53245aa00e22..289df38fb7e0 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -26,6 +26,8 @@
 #ifdef CONFIG_HUGETLB_PAGE
 
 #define PAGE_SHIFT_64K	16
+#define PAGE_SHIFT_512K	19
+#define PAGE_SHIFT_8M	23
 #define PAGE_SHIFT_16M	24
 #define PAGE_SHIFT_16G	34
 
@@ -38,7 +40,7 @@ unsigned int HPAGE_SHIFT;
  * implementations may have more than one gpage size, so we need multiple
  * arrays
  */
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 #define MAX_NUMBER_GPAGES	128
 struct psize_gpages {
 	u64 gpage_list[MAX_NUMBER_GPAGES];
@@ -105,6 +107,11 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
 #ifdef CONFIG_PPC_BOOK3S_64
 			hpdp->pd = __pa(new) |
 				   (shift_to_mmu_psize(pshift) << 2);
+#elif defined(CONFIG_PPC_8xx)
+			hpdp->pd = __pa(new) |
+				   (pshift == PAGE_SHIFT_8M ? _PMD_PAGE_8M :
+							      _PMD_PAGE_512K) |
+				   _PMD_PRESENT;
 #else
 			/* We use the old format for PPC_FSL_BOOK3E */
 			hpdp->pd = ((unsigned long)new & ~PD_HUGE) | pshift;
@@ -124,7 +131,7 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
  * These macros define how to determine which level of the page table holds
  * the hpdp.
  */
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 #define HUGEPD_PGD_SHIFT PGDIR_SHIFT
 #define HUGEPD_PUD_SHIFT PUD_SHIFT
 #else
@@ -200,7 +207,7 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
 	return hugepte_offset(*hpdp, addr, pdshift);
 }
 
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 /* Build list of addresses of gigantic pages.  This function is used in early
  * boot before the buddy allocator is setup.
  */
@@ -366,7 +373,7 @@ int alloc_bootmem_huge_page(struct hstate *hstate)
 }
 #endif
 
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 #define HUGEPD_FREELIST_SIZE \
 	((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
 
@@ -735,10 +742,10 @@ static int __init add_huge_page_size(unsigned long long size)
 	 * that it fits within pagetable and slice limits. */
 	if (size <= PAGE_SIZE)
 		return -EINVAL;
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E)
 	if (!is_power_of_4(size))
 		return -EINVAL;
-#else
+#elif !defined(CONFIG_PPC_8xx)
 	if (!is_power_of_2(size) || (shift > SLICE_HIGH_SHIFT))
 		return -EINVAL;
 #endif
@@ -777,7 +784,7 @@ static int __init hugetlbpage_init(void)
 {
 	int psize;
 
-#if !defined(CONFIG_PPC_FSL_BOOK3E)
+#if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
 	if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
 		return -ENODEV;
 #endif
@@ -809,7 +816,7 @@ static int __init hugetlbpage_init(void)
 				panic("hugetlbpage_init(): could not create "
 				      "pgtable cache for %d bit pagesize\n", shift);
 		}
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 		else if (!hugepte_cache) {
 			/*
 			 * Create a kmem cache for hugeptes.  The bottom bits in
@@ -828,10 +835,12 @@ static int __init hugetlbpage_init(void)
 #endif
 	}
 
-#ifdef CONFIG_PPC_FSL_BOOK3E
-	/* Default hpage size = 4M */
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
+	/* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
 	if (mmu_psize_defs[MMU_PAGE_4M].shift)
 		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
+	else if (mmu_psize_defs[MMU_PAGE_512K].shift)
+		HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
 #else
 	/* Set default large page size. Currently, we pick 16M or 1M
 	 * depending on what is available