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>

3 files changed, 136 insertions, 6 deletions

diff --git a/arch/sh/include/asm/cacheflush.h b/arch/sh/include/asm/cacheflush.h
index 09acbc32d6c7..4c5462daa74c 100644
--- a/arch/sh/include/asm/cacheflush.h
+++ b/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 */
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index b517ae08b9c0..2a011b18090b 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/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 */
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index 931f4d003fa0..1b5fdfb4e0c2 100644
--- a/arch/sh/mm/mmap.c
+++ b/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 @@ full_search:
                         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 */
 
 /*