[SPARC64]: Fix 2 bugs in huge page support.

1) huge_pte_offset() did not check the page table hierarchy
   elements as being empty correctly, resulting in an OOPS

2) Need platform specific hugetlb_get_unmapped_area() to handle
   the top-down vs. bottom-up address space allocation strategies.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/mm/hugetlbpage.c

 /*
  * SPARC64 Huge TLB page support.
  *
- * Copyright (C) 2002, 2003 David S. Miller (davem@redhat.com)
+ * Copyright (C) 2002, 2003, 2006 David S. Miller (davem@davemloft.net)
  */
 
 #include <linux/config.h>
@@ -22,6 +22,175 @@
 #include <asm/cacheflush.h>
 #include <asm/mmu_context.h>
 
+/* Slightly simplified from the non-hugepage variant because by
+ * definition we don't have to worry about any page coloring stuff
+ */
+#define VA_EXCLUDE_START (0x0000080000000000UL - (1UL << 32UL))
+#define VA_EXCLUDE_END   (0xfffff80000000000UL + (1UL << 32UL))
+
+static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
+							unsigned long addr,
+							unsigned long len,
+							unsigned long pgoff,
+							unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct * vma;
+	unsigned long task_size = TASK_SIZE;
+	unsigned long start_addr;
+
+	if (test_thread_flag(TIF_32BIT))
+		task_size = STACK_TOP32;
+	if (unlikely(len >= VA_EXCLUDE_START))
+		return -ENOMEM;
+
+	if (len > mm->cached_hole_size) {
+	        start_addr = addr = mm->free_area_cache;
+	} else {
+	        start_addr = addr = TASK_UNMAPPED_BASE;
+	        mm->cached_hole_size = 0;
+	}
+
+	task_size -= len;
+
+full_search:
+	addr = ALIGN(addr, HPAGE_SIZE);
+
+	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
+		/* At this point:  (!vma || addr < vma->vm_end). */
+		if (addr < VA_EXCLUDE_START &&
+		    (addr + len) >= VA_EXCLUDE_START) {
+			addr = VA_EXCLUDE_END;
+			vma = find_vma(mm, VA_EXCLUDE_END);
+		}
+		if (unlikely(task_size < addr)) {
+			if (start_addr != TASK_UNMAPPED_BASE) {
+				start_addr = addr = TASK_UNMAPPED_BASE;
+				mm->cached_hole_size = 0;
+				goto full_search;
+			}
+			return -ENOMEM;
+		}
+		if (likely(!vma || addr + len <= vma->vm_start)) {
+			/*
+			 * Remember the place where we stopped the search:
+			 */
+			mm->free_area_cache = addr + len;
+			return addr;
+		}
+		if (addr + mm->cached_hole_size < vma->vm_start)
+		        mm->cached_hole_size = vma->vm_start - addr;
+
+		addr = ALIGN(vma->vm_end, HPAGE_SIZE);
+	}
+}
+
+static unsigned long
+hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+				  const unsigned long len,
+				  const unsigned long pgoff,
+				  const unsigned long flags)
+{
+	struct vm_area_struct *vma;
+	struct mm_struct *mm = current->mm;
+	unsigned long addr = addr0;
+
+	/* This should only ever run for 32-bit processes.  */
+	BUG_ON(!test_thread_flag(TIF_32BIT));
+
+	/* check if free_area_cache is useful for us */
+	if (len <= mm->cached_hole_size) {
+ 	        mm->cached_hole_size = 0;
+ 		mm->free_area_cache = mm->mmap_base;
+ 	}
+
+	/* either no address requested or can't fit in requested address hole */
+	addr = mm->free_area_cache & HPAGE_MASK;
+
+	/* make sure it can fit in the remaining address space */
+	if (likely(addr > len)) {
+		vma = find_vma(mm, addr-len);
+		if (!vma || addr <= vma->vm_start) {
+			/* remember the address as a hint for next time */
+			return (mm->free_area_cache = addr-len);
+		}
+	}
+
+	if (unlikely(mm->mmap_base < len))
+		goto bottomup;
+
+	addr = (mm->mmap_base-len) & HPAGE_MASK;
+
+	do {
+		/*
+		 * Lookup failure means no vma is above this address,
+		 * else if new region fits below vma->vm_start,
+		 * return with success:
+		 */
+		vma = find_vma(mm, addr);
+		if (likely(!vma || addr+len <= vma->vm_start)) {
+			/* remember the address as a hint for next time */
+			return (mm->free_area_cache = addr);
+		}
+
+ 		/* remember the largest hole we saw so far */
+ 		if (addr + mm->cached_hole_size < vma->vm_start)
+ 		        mm->cached_hole_size = vma->vm_start - addr;
+
+		/* try just below the current vma->vm_start */
+		addr = (vma->vm_start-len) & HPAGE_MASK;
+	} while (likely(len < vma->vm_start));
+
+bottomup:
+	/*
+	 * A failed mmap() very likely causes application failure,
+	 * so fall back to the bottom-up function here. This scenario
+	 * can happen with large stack limits and large mmap()
+	 * allocations.
+	 */
+	mm->cached_hole_size = ~0UL;
+  	mm->free_area_cache = TASK_UNMAPPED_BASE;
+	addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
+	/*
+	 * Restore the topdown base:
+	 */
+	mm->free_area_cache = mm->mmap_base;
+	mm->cached_hole_size = ~0UL;
+
+	return addr;
+}
+
+unsigned long
+hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long task_size = TASK_SIZE;
+
+	if (test_thread_flag(TIF_32BIT))
+		task_size = STACK_TOP32;
+
+	if (len & ~HPAGE_MASK)
+		return -EINVAL;
+	if (len > task_size)
+		return -ENOMEM;
+
+	if (addr) {
+		addr = ALIGN(addr, HPAGE_SIZE);
+		vma = find_vma(mm, addr);
+		if (task_size - len >= addr &&
+		    (!vma || addr + len <= vma->vm_start))
+			return addr;
+	}
+	if (mm->get_unmapped_area == arch_get_unmapped_area)
+		return hugetlb_get_unmapped_area_bottomup(file, addr, len,
+				pgoff, flags);
+	else
+		return hugetlb_get_unmapped_area_topdown(file, addr, len,
+				pgoff, flags);
+}
+
 pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
 {
 	pgd_t *pgd;
@@ -48,12 +217,14 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 	pmd_t *pmd;
 	pte_t *pte = NULL;
 
+	addr &= HPAGE_MASK;
+
 	pgd = pgd_offset(mm, addr);
-	if (pgd) {
+	if (!pgd_none(*pgd)) {
 		pud = pud_offset(pgd, addr);
-		if (pud) {
+		if (!pud_none(*pud)) {
 			pmd = pmd_offset(pud, addr);
-			if (pmd)
+			if (!pmd_none(*pmd))
 				pte = pte_offset_map(pmd, addr);
 		}
 	}

include/asm-sparc64/page.h

@@ -104,6 +104,7 @@ typedef unsigned long pgprot_t;
 #define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)
 #define ARCH_HAS_SETCLEAR_HUGE_PTE
 #define ARCH_HAS_HUGETLB_PREFAULT_HOOK
+#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 #endif
 
 #define TASK_UNMAPPED_BASE	(test_thread_flag(TIF_32BIT) ? \