[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>

2 files changed, 176 insertions, 4 deletions

diff --git a/arch/sparc64/mm/hugetlbpage.c b/arch/sparc64/mm/hugetlbpage.c
index 625cbb336a23..a7a24869d045 100644
--- a/arch/sparc64/mm/hugetlbpage.c
+++ b/arch/sparc64/mm/hugetlbpage.c
@@ -1,7 +1,7 @@
 /*
  * 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);
                 }
         }
diff --git a/include/asm-sparc64/page.h b/include/asm-sparc64/page.h
index f6b49256fe2b..fcb2812265f4 100644
--- a/include/asm-sparc64/page.h
+++ b/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) ? \