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);
+}
+