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-rw-r--r--arch/metag/mm/highmem.c133
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/metag/mm/highmem.c b/arch/metag/mm/highmem.c
new file mode 100644
index 000000000000..d71f621a2c0b
--- /dev/null
+++ b/arch/metag/mm/highmem.c
@@ -0,0 +1,133 @@
+#include <linux/export.h>
+#include <linux/highmem.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <asm/fixmap.h>
+#include <asm/tlbflush.h>
+
+static pte_t *kmap_pte;
+
+unsigned long highstart_pfn, highend_pfn;
+
+void *kmap(struct page *page)
+{
+ might_sleep();
+ if (!PageHighMem(page))
+ return page_address(page);
+ return kmap_high(page);
+}
+EXPORT_SYMBOL(kmap);
+
+void kunmap(struct page *page)
+{
+ BUG_ON(in_interrupt());
+ if (!PageHighMem(page))
+ return;
+ kunmap_high(page);
+}
+EXPORT_SYMBOL(kunmap);
+
+/*
+ * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
+ * no global lock is needed and because the kmap code must perform a global TLB
+ * invalidation when the kmap pool wraps.
+ *
+ * However when holding an atomic kmap is is not legal to sleep, so atomic
+ * kmaps are appropriate for short, tight code paths only.
+ */
+
+void *kmap_atomic(struct page *page)
+{
+ enum fixed_addresses idx;
+ unsigned long vaddr;
+ int type;
+
+ /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ 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));
+
+ return (void *)vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic);
+
+void __kunmap_atomic(void *kvaddr)
+{
+ unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+ int idx, type;
+
+ if (kvaddr >= (void *)FIXADDR_START) {
+ 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, vaddr, kmap_pte-idx);
+ flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
+
+ kmap_atomic_idx_pop();
+ }
+
+ pagefault_enable();
+}
+EXPORT_SYMBOL(__kunmap_atomic);
+
+/*
+ * This is the same as kmap_atomic() but can map memory that doesn't
+ * have a struct page associated with it.
+ */
+void *kmap_atomic_pfn(unsigned long pfn)
+{
+ enum fixed_addresses idx;
+ unsigned long vaddr;
+ int type;
+
+ pagefault_disable();
+
+ 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, pfn_pte(pfn, PAGE_KERNEL));
+ flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
+
+ return (void *)vaddr;
+}
+
+struct page *kmap_atomic_to_page(void *ptr)
+{
+ unsigned long vaddr = (unsigned long)ptr;
+ int idx;
+ 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);
+}
+
+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);
+}