mm: use vm_unmapped_area() on arm architecture

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

[akpm@linux-foundation.org: remove now-unused COLOUR_ALIGN_DOWN()]
Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 109 deletions

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index ce8cb1970d7a..2065b603763c 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -11,18 +11,6 @@
 #include <linux/random.h>
 #include <asm/cachetype.h>
 
-static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
-                                              unsigned long pgoff)
-{
-        unsigned long base = addr & ~(SHMLBA-1);
-        unsigned long off = (pgoff << PAGE_SHIFT) & (SHMLBA-1);
-
-        if (base + off <= addr)
-                return base + off;
-
-        return base - off;
-}
-
 #define COLOUR_ALIGN(addr,pgoff)                \
         ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
          (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
@@ -69,9 +57,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
-        unsigned long start_addr;
         int do_align = 0;
         int aliasing = cache_is_vipt_aliasing();
+        struct vm_unmapped_area_info info;
 
         /*
          * We only need to do colour alignment if either the I or D
@@ -104,46 +92,14 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
                     (!vma || addr + len <= vma->vm_start))
                         return addr;
         }
-        if (len > mm->cached_hole_size) {
-                start_addr = addr = mm->free_area_cache;
-        } else {
-                start_addr = addr = mm->mmap_base;
-                mm->cached_hole_size = 0;
-        }
 
-full_search:
-        if (do_align)
-                addr = COLOUR_ALIGN(addr, pgoff);
-        else
-                addr = PAGE_ALIGN(addr);
-
-        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
-                /* At this point:  (!vma || addr < vma->vm_end). */
-                if (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 (!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_align)
-                        addr = COLOUR_ALIGN(addr, pgoff);
-        }
+        info.flags = 0;
+        info.length = len;
+        info.low_limit = mm->mmap_base;
+        info.high_limit = TASK_SIZE;
+        info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
+        info.align_offset = pgoff << PAGE_SHIFT;
+        return vm_unmapped_area(&info);
 }
 
 unsigned long
@@ -156,6 +112,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
         unsigned long addr = addr0;
         int do_align = 0;
         int aliasing = cache_is_vipt_aliasing();
+        struct vm_unmapped_area_info info;
 
         /*
          * We only need to do colour alignment if either the I or D
@@ -187,70 +144,27 @@ 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_align) {
-                unsigned long base = COLOUR_ALIGN_DOWN(addr - len, pgoff);
-                addr = base + len;
-        }
-
-        /* make sure it can fit in the remaining address space */
-        if (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 (mm->mmap_base < len)
-                goto bottomup;
-
-        addr = mm->mmap_base - len;
-        if (do_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 (!vma || addr+len <= vma->vm_start)
-                        /* remember the address as a hint for next time */
-                        return (mm->free_area_cache = addr);
+        info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+        info.length = len;
+        info.low_limit = PAGE_SIZE;
+        info.high_limit = mm->mmap_base;
+        info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
+        info.align_offset = pgoff << PAGE_SHIFT;
+        addr = vm_unmapped_area(&info);
 
-                /* 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_align)
-                        addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-        } while (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;
+        if (addr & ~PAGE_MASK) {
+                VM_BUG_ON(addr != -ENOMEM);
+                info.flags = 0;
+                info.low_limit = mm->mmap_base;
+                info.high_limit = TASK_SIZE;
+                addr = vm_unmapped_area(&info);
+        }
 
         return addr;
 }