ARC: [mm] Aliasing VIPT dcache support 4/4

Enforce congruency of userspace shared mappings

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

2 files changed, 79 insertions, 1 deletions

diff --git a/arch/arc/mm/Makefile b/arch/arc/mm/Makefile
index 168dc146a8f6..ac95cc239c1e 100644
--- a/arch/arc/mm/Makefile
+++ b/arch/arc/mm/Makefile
@@ -7,4 +7,4 @@
 #
 
 obj-y   := extable.o ioremap.o dma.o fault.o init.o
-obj-y   += tlb.o tlbex.o cache_arc700.o
+obj-y   += tlb.o tlbex.o cache_arc700.o mmap.o
diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c
new file mode 100644
index 000000000000..2e06d56e987b
--- /dev/null
+++ b/arch/arc/mm/mmap.c
@@ -0,0 +1,78 @@
+/*
+ * ARC700 mmap
+ *
+ * (started from arm version - for VIPT alias handling)
+ *
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/sched.h>
+#include <asm/cacheflush.h>
+
+#define COLOUR_ALIGN(addr, pgoff)                       \
+        ((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) +      \
+         (((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
+
+/*
+ * Ensure that shared mappings are correctly aligned to
+ * avoid aliasing issues with VIPT caches.
+ * We need to ensure that
+ * a specific page of an object is always mapped at a multiple of
+ * SHMLBA bytes.
+ */
+unsigned long
+arch_get_unmapped_area(struct file *filp, unsigned long addr,
+                unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+        struct mm_struct *mm = current->mm;
+        struct vm_area_struct *vma;
+        int do_align = 0;
+        int aliasing = cache_is_vipt_aliasing();
+        struct vm_unmapped_area_info info;
+
+        /*
+         * We only need to do colour alignment if D cache aliases.
+         */
+        if (aliasing)
+                do_align = filp || (flags & MAP_SHARED);
+
+        /*
+         * We enforce the MAP_FIXED case.
+         */
+        if (flags & MAP_FIXED) {
+                if (aliasing && flags & MAP_SHARED &&
+                    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
+                        return -EINVAL;
+                return addr;
+        }
+
+        if (len > TASK_SIZE)
+                return -ENOMEM;
+
+        if (addr) {
+                if (do_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;
+        }
+
+        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);
+}