1 files changed, 77 insertions, 0 deletions

diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c
new file mode 100644
index 000000000000..c2186c74c85a
--- /dev/null
+++ b/arch/powerpc/mm/highmem.c
@@ -0,0 +1,77 @@
+/*
+ * highmem.c: virtual kernel memory mappings for high memory
+ *
+ * PowerPC version, stolen from the i386 version.
+ *
+ * Used in CONFIG_HIGHMEM systems for memory pages which
+ * are not addressable by direct kernel virtual addresses.
+ *
+ * Copyright (C) 1999 Gerhard Wichert, Siemens AG
+ *                    Gerhard.Wichert@pdb.siemens.de
+ *
+ *
+ * Redesigned the x86 32-bit VM architecture to deal with
+ * up to 16 Terrabyte physical memory. With current x86 CPUs
+ * we now support up to 64 Gigabytes physical RAM.
+ *
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ *
+ * Reworked for PowerPC by various contributors. Moved from
+ * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
+ */
+
+#include <linux/highmem.h>
+#include <linux/module.h>
+
+/*
+ * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
+ * gives a more generic (and caching) interface. But kmap_atomic can
+ * be used in IRQ contexts, so in some (very limited) cases we need
+ * it.
+ */
+void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
+{
+        unsigned int idx;
+        unsigned long vaddr;
+
+        /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+        pagefault_disable();
+        if (!PageHighMem(page))
+                return page_address(page);
+
+        debug_kmap_atomic(type);
+        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_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
+        local_flush_tlb_page(NULL, vaddr);
+
+        return (void*) vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic_prot);
+
+void kunmap_atomic(void *kvaddr, enum km_type type)
+{
+#ifdef CONFIG_DEBUG_HIGHMEM
+        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+        enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
+
+        if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
+                pagefault_enable();
+                return;
+        }
+
+        BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
+
+        /*
+         * force other mappings to Oops if they'll try to access
+         * this pte without first remap it
+         */
+        pte_clear(&init_mm, vaddr, kmap_pte-idx);
+        local_flush_tlb_page(NULL, vaddr);
+#endif
+        pagefault_enable();
+}
+EXPORT_SYMBOL(kunmap_atomic);