Subject: [PATCH 7/8] mm: use vm_unmapped_area() on powerpc architecture

From: Michel Lespinasse <[email-masked]>
Date: Tue, 8 Jan 2013 17:28:14 -0800

Update the powerpc slice_get_unmapped_area function to make use of
vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <[email-masked]>

---
 arch/powerpc/mm/slice.c |  128 +++++++++++++++++++++++++++++-----------------
 1 files changed, 81 insertions(+), 47 deletions(-)

diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 999a74f25ebe..048346b7eed5 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -242,31 +242,51 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 					      struct slice_mask available,
 					      int psize)
 {
-	struct vm_area_struct *vma;
-	unsigned long addr;
-	struct slice_mask mask;
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
+	unsigned long addr, found, slice;
+	struct vm_unmapped_area_info info;
 
-	addr = TASK_UNMAPPED_BASE;
+	info.flags = 0;
+	info.length = len;
+	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
+	info.align_offset = 0;
 
-	for (;;) {
-		addr = _ALIGN_UP(addr, 1ul << pshift);
-		if ((TASK_SIZE - len) < addr)
-			break;
-		vma = find_vma(mm, addr);
-		BUG_ON(vma && (addr >= vma->vm_end));
+	addr = TASK_UNMAPPED_BASE;
+	while (addr < TASK_SIZE) {
+		info.low_limit = addr;
+		if (addr < SLICE_LOW_TOP) {
+			slice = GET_LOW_SLICE_INDEX(addr);
+			addr = (slice + 1) << SLICE_LOW_SHIFT;
+			if (!(available.low_slices & (1u << slice)))
+				continue;
+		} else {
+			slice = GET_HIGH_SLICE_INDEX(addr);
+			addr = (slice + 1) << SLICE_HIGH_SHIFT;
+			if (!(available.high_slices & (1u << slice)))
+				continue;
+		}
 
-		mask = slice_range_to_mask(addr, len);
-		if (!slice_check_fit(mask, available)) {
-			if (addr < SLICE_LOW_TOP)
-				addr = _ALIGN_UP(addr + 1,  1ul << SLICE_LOW_SHIFT);
-			else
-				addr = _ALIGN_UP(addr + 1,  1ul << SLICE_HIGH_SHIFT);
-			continue;
+ next_slice:
+		if (addr >= TASK_SIZE)
+			addr = TASK_SIZE;
+		else if (addr < SLICE_LOW_TOP) {
+			slice = GET_LOW_SLICE_INDEX(addr);
+			if (available.low_slices & (1u << slice)) {
+				addr = (slice + 1) << SLICE_LOW_SHIFT;
+				goto next_slice;
+			}
+		} else {
+			slice = GET_HIGH_SLICE_INDEX(addr);
+			if (available.high_slices & (1u << slice)) {
+				addr = (slice + 1) << SLICE_HIGH_SHIFT;
+				goto next_slice;
+			}
 		}
-		if (!vma || addr + len <= vma->vm_start)
-			return addr;
-		addr = vma->vm_end;
+		info.high_limit = addr;
+
+		found = vm_unmapped_area(&info);
+		if (!(found & ~PAGE_MASK))
+			return found;
 	}
 
 	return -ENOMEM;
@@ -277,39 +297,53 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 					     struct slice_mask available,
 					     int psize)
 {
-	struct vm_area_struct *vma;
-	unsigned long addr;
-	struct slice_mask mask;
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
+	unsigned long addr, found, slice;
+	struct vm_unmapped_area_info info;
 
-	addr = mm->mmap_base;
-	while (addr > len) {
-		/* Go down by chunk size */
-		addr = _ALIGN_DOWN(addr - len, 1ul << pshift);
+	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+	info.length = len;
+	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
+	info.align_offset = 0;
 
-		/* Check for hit with different page size */
-		mask = slice_range_to_mask(addr, len);
-		if (!slice_check_fit(mask, available)) {
-			if (addr < SLICE_LOW_TOP)
-				addr = _ALIGN_DOWN(addr, 1ul << SLICE_LOW_SHIFT);
-			else if (addr < (1ul << SLICE_HIGH_SHIFT))
-				addr = SLICE_LOW_TOP;
-			else
-				addr = _ALIGN_DOWN(addr, 1ul << SLICE_HIGH_SHIFT);
-			continue;
+	addr = mm->mmap_base;
+	while (addr > PAGE_SIZE) {
+		info.high_limit = addr;
+                if (addr < SLICE_LOW_TOP) {
+			slice = GET_LOW_SLICE_INDEX(addr - 1);
+			addr = slice << SLICE_LOW_SHIFT;
+			if (!(available.low_slices & (1u << slice)))
+				continue;
+		} else {
+			slice = GET_HIGH_SLICE_INDEX(addr - 1);
+			addr = slice ? (slice << SLICE_HIGH_SHIFT) :
+								SLICE_LOW_TOP;
+			if (!(available.high_slices & (1u << slice)))
+				continue;
 		}
 
-		/*
-		 * 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 (!vma || (addr + len) <= vma->vm_start)
-			return addr;
+ next_slice:
+		if (addr < PAGE_SIZE)
+			addr = PAGE_SIZE;
+		else if (addr < SLICE_LOW_TOP) {
+			slice = GET_LOW_SLICE_INDEX(addr - 1);
+			if (available.low_slices & (1u << slice)) {
+				addr = slice << SLICE_LOW_SHIFT;
+				goto next_slice;
+			}
+		} else {
+			slice = GET_HIGH_SLICE_INDEX(addr - 1);
+			if (available.high_slices & (1u << slice)) {
+				addr = slice ? (slice << SLICE_HIGH_SHIFT) :
+								SLICE_LOW_TOP;
+				goto next_slice;
+			}
+		}
+		info.low_limit = addr;
 
-		/* try just below the current vma->vm_start */
-		addr = vma->vm_start;
+		found = vm_unmapped_area(&info);
+		if (!(found & ~PAGE_MASK))
+			return found;
 	}
 
 	/*
-- 
1.7.7.3