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-rw-r--r--arch/i386/mm/highmem.c89
1 files changed, 89 insertions, 0 deletions
diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c
new file mode 100644
index 000000000000..fc4c4cad4e98
--- /dev/null
+++ b/arch/i386/mm/highmem.c
@@ -0,0 +1,89 @@
+#include <linux/highmem.h>
+
+void *kmap(struct page *page)
+{
+ might_sleep();
+ if (!PageHighMem(page))
+ return page_address(page);
+ return kmap_high(page);
+}
+
+void kunmap(struct page *page)
+{
+ if (in_interrupt())
+ BUG();
+ if (!PageHighMem(page))
+ return;
+ kunmap_high(page);
+}
+
+/*
+ * 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 km_type type)
+{
+ enum fixed_addresses idx;
+ unsigned long vaddr;
+
+ /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ inc_preempt_count();
+ 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
+ if (!pte_none(*(kmap_pte-idx)))
+ BUG();
+#endif
+ set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
+ __flush_tlb_one(vaddr);
+
+ return (void*) vaddr;
+}
+
+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 < FIXADDR_START) { // FIXME
+ dec_preempt_count();
+ preempt_check_resched();
+ return;
+ }
+
+ if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
+ BUG();
+
+ /*
+ * 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_one(vaddr);
+#endif
+
+ dec_preempt_count();
+ preempt_check_resched();
+}
+
+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);
+}
+