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authorJames Morris <jmorris@namei.org>2009-06-30 09:10:35 +1000
committerJames Morris <jmorris@namei.org>2009-06-30 09:10:35 +1000
commitac7242142b03421c96b0a2f8d99f146d075614c2 (patch)
treeb0b2ead65858c7a343d38affed86fe815e37e7e9 /arch/powerpc/mm/highmem.c
parent89c86576ecde504da1eeb4f4882b2189ac2f9c4a (diff)
parent2bfdd79eaa0043346e773ba5f6cfd811ea31b73d (diff)
Merge branch 'master' into next
Diffstat (limited to 'arch/powerpc/mm/highmem.c')
-rw-r--r--arch/powerpc/mm/highmem.c77
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 00000000000..c2186c74c85
--- /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);