+unsigned long
+arch_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 task_size = STACK_TOP32;
+ unsigned long addr = addr0;
+ int do_color_align;
+
+ /* This should only ever run for 32-bit processes. */
+ BUG_ON(!test_thread_flag(TIF_32BIT));
+
+ if (flags & MAP_FIXED) {
+ /* We do not accept a shared mapping if it would violate
+ * cache aliasing constraints.
+ */
+ if ((flags & MAP_SHARED) &&
+ ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
+ return -EINVAL;
+ return addr;
+ }
+
+ if (unlikely(len > task_size))
+ return -ENOMEM;
+
+ do_color_align = 0;
+ if (filp || (flags & MAP_SHARED))
+ do_color_align = 1;
+
+ /* requesting a specific address */
+ if (addr) {
+ if (do_color_align)
+ addr = COLOUR_ALIGN(addr, pgoff);
+ else
+ addr = PAGE_ALIGN(addr);
+
+ vma = find_vma(mm, addr);
+ if (task_size - len >= addr &&
+ (!vma || addr + len <= vma->vm_start))
+ 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_color_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_color_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_color_align)
+ addr = COLOUR_ALIGN_DOWN(addr, pgoff);
+ } 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;
+}
+