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, 18 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index c5517f463ec7..3facdd41709c 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -51,12 +51,20 @@ static inline void __local_flush_hugetlb_page(struct vm_area_struct *vma,
 static inline pte_t *hugepd_page(hugepd_t hpd)
 {
 	BUG_ON(!hugepd_ok(hpd));
+#ifdef CONFIG_PPC_8xx
+	return (pte_t *)__va(hpd.pd & ~(_PMD_PAGE_MASK | _PMD_PRESENT_MASK));
+#else
 	return (pte_t *)((hpd.pd & ~HUGEPD_SHIFT_MASK) | PD_HUGE);
+#endif
 }
 
 static inline unsigned int hugepd_shift(hugepd_t hpd)
 {
+#ifdef CONFIG_PPC_8xx
+	return ((hpd.pd & _PMD_PAGE_MASK) >> 1) + 17;
+#else
 	return hpd.pd & HUGEPD_SHIFT_MASK;
+#endif
 }
 
 #endif /* CONFIG_PPC_BOOK3S_64 */
@@ -99,7 +107,15 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 
 void book3e_hugetlb_preload(struct vm_area_struct *vma, unsigned long ea,
 			    pte_t pte);
+#ifdef CONFIG_PPC_8xx
+static inline void flush_hugetlb_page(struct vm_area_struct *vma,
+				      unsigned long vmaddr)
+{
+	flush_tlb_page(vma, vmaddr);
+}
+#else
 void flush_hugetlb_page(struct vm_area_struct *vma, unsigned long vmaddr);
+#endif
 
 void hugetlb_free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
 			    unsigned long end, unsigned long floor,
@@ -205,7 +221,8 @@ static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
  * are reserved early in the boot process by memblock instead of via
  * the .dts as on IBM platforms.
  */
-#if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_PPC_FSL_BOOK3E)
+#if defined(CONFIG_HUGETLB_PAGE) && (defined(CONFIG_PPC_FSL_BOOK3E) || \
+    defined(CONFIG_PPC_8xx))
 extern void __init reserve_hugetlb_gpages(void);
 #else
 static inline void reserve_hugetlb_gpages(void)