sh: Handle shm_align_mask also for HAVE_ARCH_UNMAPPED_AREA_TOPDOWN.

Presently shm_align_mask is only looked at for the bottom up case, but we
still want this for proper colouring constraints in the topdown case.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/cacheflush.h

@@ -75,7 +75,5 @@ extern void copy_from_user_page(struct vm_area_struct *vma,
 #define flush_cache_vmap(start, end)		flush_cache_all()
 #define flush_cache_vunmap(start, end)		flush_cache_all()
 
-#define HAVE_ARCH_UNMAPPED_AREA
-
 #endif /* __KERNEL__ */
 #endif /* __ASM_SH_CACHEFLUSH_H */

arch/sh/include/asm/pgtable.h

@@ -154,6 +154,10 @@ extern void kmap_coherent_init(void);
 #define kmap_coherent_init()	do { } while (0)
 #endif
 
+/* arch/sh/mm/mmap.c */
+#define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+
 #include <asm-generic/pgtable.h>
 
 #endif /* __ASM_SH_PGTABLE_H */

arch/sh/mm/mmap.c

@@ -1,7 +1,7 @@
 /*
  * arch/sh/mm/mmap.c
  *
- * Copyright (C) 2008  Paul Mundt
+ * Copyright (C) 2008 - 2009  Paul Mundt
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
@@ -21,9 +21,26 @@ EXPORT_SYMBOL(shm_align_mask);
 /*
  * To avoid cache aliases, we map the shared page with same color.
  */
-#define COLOUR_ALIGN(addr, pgoff)				\
-	((((addr) + shm_align_mask) & ~shm_align_mask) +	\
-	 (((pgoff) << PAGE_SHIFT) & shm_align_mask))
+static inline unsigned long COLOUR_ALIGN(unsigned long addr,
+					 unsigned long pgoff)
+{
+	unsigned long base = (addr + shm_align_mask) & ~shm_align_mask;
+	unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
+
+	return base + off;
+}
+
+static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
+					      unsigned long pgoff)
+{
+	unsigned long base = addr & ~shm_align_mask;
+	unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
+
+	if (base + off <= addr)
+		return base + off;
+
+	return base - off;
+}
 
 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	unsigned long len, unsigned long pgoff, unsigned long flags)
@@ -103,6 +120,117 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 			addr = COLOUR_ALIGN(addr, pgoff);
 	}
 }
+
+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 addr = addr0;
+	int do_colour_align;
+
+	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)) & shm_align_mask))
+			return -EINVAL;
+		return addr;
+	}
+
+	if (unlikely(len > TASK_SIZE))
+		return -ENOMEM;
+
+	do_colour_align = 0;
+	if (filp || (flags & MAP_SHARED))
+		do_colour_align = 1;
+
+	/* requesting a specific address */
+	if (addr) {
+		if (do_colour_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_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:
+	/*
+	 * 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;
+}
 #endif /* CONFIG_MMU */
 
 /*