1 files changed, 138 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/highmem.h b/arch/powerpc/include/asm/highmem.h
new file mode 100644
index 000000000000..5d99b6489d56
--- /dev/null
+++ b/arch/powerpc/include/asm/highmem.h
@@ -0,0 +1,138 @@
+/*
+ * highmem.h: 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>
+ */
+
+#ifndef _ASM_HIGHMEM_H
+#define _ASM_HIGHMEM_H
+
+#ifdef __KERNEL__
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <asm/kmap_types.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+#include <asm/fixmap.h>
+
+extern pte_t *kmap_pte;
+extern pgprot_t kmap_prot;
+extern pte_t *pkmap_page_table;
+
+/*
+ * Right now we initialize only a single pte table. It can be extended
+ * easily, subsequent pte tables have to be allocated in one physical
+ * chunk of RAM.
+ */
+#define LAST_PKMAP      (1 << PTE_SHIFT)
+#define LAST_PKMAP_MASK (LAST_PKMAP-1)
+#define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
+#define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
+#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
+
+extern void *kmap_high(struct page *page);
+extern void kunmap_high(struct page *page);
+
+static inline void *kmap(struct page *page)
+{
+        might_sleep();
+        if (!PageHighMem(page))
+                return page_address(page);
+        return kmap_high(page);
+}
+
+static inline void kunmap(struct page *page)
+{
+        BUG_ON(in_interrupt());
+        if (!PageHighMem(page))
+                return;
+        kunmap_high(page);
+}
+
+/*
+ * 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.
+ */
+static inline 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);
+
+        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));
+        flush_tlb_page(NULL, vaddr);
+
+        return (void*) vaddr;
+}
+
+static inline void *kmap_atomic(struct page *page, enum km_type type)
+{
+        return kmap_atomic_prot(page, type, kmap_prot);
+}
+
+static inline 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);
+        flush_tlb_page(NULL, vaddr);
+#endif
+        pagefault_enable();
+}
+
+static inline struct page *kmap_atomic_to_page(void *ptr)
+{
+        unsigned long idx, vaddr = (unsigned long) ptr;
+        pte_t *pte;
+
+        if (vaddr < FIXADDR_START)
+                return virt_to_page(ptr);
+
+        idx = virt_to_fix(vaddr);
+        pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
+        return pte_page(*pte);
+}
+
+#define flush_cache_kmaps()     flush_cache_all()
+
+#endif /* __KERNEL__ */
+
+#endif /* _ASM_HIGHMEM_H */