1 files changed, 72 insertions, 0 deletions

diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
new file mode 100644
index 000000000000..17a8c0d6fd17
--- /dev/null
+++ b/arch/xtensa/mm/highmem.c
@@ -0,0 +1,72 @@
+/*
+ * High memory support for Xtensa architecture
+ *
+ * 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 for more details.
+ *
+ * Copyright (C) 2014 Cadence Design Systems Inc.
+ */
+
+#include <linux/export.h>
+#include <linux/highmem.h>
+#include <asm/tlbflush.h>
+
+static pte_t *kmap_pte;
+
+void *kmap_atomic(struct page *page)
+{
+        enum fixed_addresses idx;
+        unsigned long vaddr;
+        int type;
+
+        pagefault_disable();
+        if (!PageHighMem(page))
+                return page_address(page);
+
+        type = kmap_atomic_idx_push();
+        idx = type + KM_TYPE_NR * smp_processor_id();
+        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+#ifdef CONFIG_DEBUG_HIGHMEM
+        BUG_ON(!pte_none(*(kmap_pte - idx)));
+#endif
+        set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL_EXEC));
+
+        return (void *)vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic);
+
+void __kunmap_atomic(void *kvaddr)
+{
+        int idx, type;
+
+        if (kvaddr >= (void *)FIXADDR_START &&
+            kvaddr < (void *)FIXADDR_TOP) {
+                type = kmap_atomic_idx();
+                idx = type + KM_TYPE_NR * smp_processor_id();
+
+                /*
+                 * Force other mappings to Oops if they'll try to access this
+                 * pte without first remap it.  Keeping stale mappings around
+                 * is a bad idea also, in case the page changes cacheability
+                 * attributes or becomes a protected page in a hypervisor.
+                 */
+                pte_clear(&init_mm, kvaddr, kmap_pte - idx);
+                local_flush_tlb_kernel_range((unsigned long)kvaddr,
+                                             (unsigned long)kvaddr + PAGE_SIZE);
+
+                kmap_atomic_idx_pop();
+        }
+
+        pagefault_enable();
+}
+EXPORT_SYMBOL(__kunmap_atomic);
+
+void __init kmap_init(void)
+{
+        unsigned long kmap_vstart;
+
+        /* cache the first kmap pte */
+        kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
+        kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
+}