[PATCH 12/16] mm: use vm_unmapped_area() on sh architecture

[Michel Lespinasse]

Update the sh arch_get_unmapped_area[_topdown] functions to make
use of vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <walken at google.com>

---
 arch/sh/mm/mmap.c |  126 ++++++++++-------------------------------------------
 1 files changed, 24 insertions(+), 102 deletions(-)

diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index afeb710ec5c3..acb3b8f71908 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -49,6 +49,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	struct vm_area_struct *vma;
 	unsigned long start_addr;
 	int do_colour_align;
+	struct vm_unmapped_area_info info;
 
 	if (flags & MAP_FIXED) {
 		/* We do not accept a shared mapping if it would violate
@@ -79,47 +80,13 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 			return addr;
 	}
 
-	if (len > mm->cached_hole_size) {
-		start_addr = addr = mm->free_area_cache;
-	} else {
-	        mm->cached_hole_size = 0;
-		start_addr = addr = TASK_UNMAPPED_BASE;
-	}
-
-full_search:
-	if (do_colour_align)
-		addr = COLOUR_ALIGN(addr, pgoff);
-	else
-		addr = PAGE_ALIGN(mm->free_area_cache);
-
-	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
-		/* At this point:  (!vma || addr < vma->vm_end). */
-		if (unlikely(TASK_SIZE - len < addr)) {
-			/*
-			 * Start a new search - just in case we missed
-			 * some holes.
-			 */
-			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 = vma->vm_end;
-		if (do_colour_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
-	}
+	info.flags = 0;
+	info.length = len;
+	info.low_limit = TASK_UNMAPPED_BASE;
+	info.high_limit = TASK_SIZE;
+	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0;
+	info.align_offset = pgoff << PAGE_SHIFT;
+	return vm_unmapped_area(&info);
 }
 
 unsigned long
@@ -131,6 +98,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
 	int do_colour_align;
+	struct vm_unmapped_area_info info;
 
 	if (flags & MAP_FIXED) {
 		/* We do not accept a shared mapping if it would violate
@@ -162,73 +130,27 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 			return addr;
 	}
 
-	/* 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;
-	if (do_colour_align) {
-		unsigned long base = COLOUR_ALIGN_DOWN(addr-len, pgoff);
-
-		addr = base + len;
-	}
-
-	/* 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;
-	if (do_colour_align)
-		addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-
-	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;
-		if (do_colour_align)
-			addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-	} while (likely(len < vma->vm_start));
-
-bottomup:
+	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+	info.length = len;
+	info.low_limit = PAGE_SIZE;
+	info.high_limit = mm->mmap_base;
+	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0;
+	info.align_offset = pgoff << PAGE_SHIFT;
+	addr = vm_unmapped_area(&info);
+	
 	/*
 	 * 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;
+	if (addr & ~PAGE_MASK) {
+		VM_BUG_ON(addr != -ENOMEM);
+		info.flags = 0;
+		info.low_limit = TASK_UNMAPPED_BASE;
+		info.high_limit = TASK_SIZE;
+		addr = vm_unmapped_area(&info);
+	}
 
 	return addr;
 }
-- 
1.7.7.3