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Diffstat (limited to 'arch/x86/mm/highmem_32.c')
-rw-r--r--arch/x86/mm/highmem_32.c113
1 files changed, 113 insertions, 0 deletions
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
new file mode 100644
index 00000000000..1c3bf95f735
--- /dev/null
+++ b/arch/x86/mm/highmem_32.c
@@ -0,0 +1,113 @@
+#include <linux/highmem.h>
+#include <linux/module.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_prot(struct page *page, enum km_type type, pgprot_t prot)
+{
+ enum fixed_addresses 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);
+ BUG_ON(!pte_none(*(kmap_pte-idx)));
+ set_pte(kmap_pte-idx, mk_pte(page, prot));
+ arch_flush_lazy_mmu_mode();
+
+ return (void *)vaddr;
+}
+
+void *kmap_atomic(struct page *page, enum km_type type)
+{
+ return kmap_atomic_prot(page, type, kmap_prot);
+}
+
+void kunmap_atomic(void *kvaddr, enum km_type type)
+{
+ unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+ enum fixed_addresses 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.
+ */
+ if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
+ kpte_clear_flush(kmap_pte-idx, vaddr);
+ else {
+#ifdef CONFIG_DEBUG_HIGHMEM
+ BUG_ON(vaddr < PAGE_OFFSET);
+ BUG_ON(vaddr >= (unsigned long)high_memory);
+#endif
+ }
+
+ arch_flush_lazy_mmu_mode();
+ pagefault_enable();
+}
+
+/* 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 km_type type)
+{
+ enum fixed_addresses idx;
+ unsigned long vaddr;
+
+ pagefault_disable();
+
+ idx = type + KM_TYPE_NR*smp_processor_id();
+ vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+ set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
+ arch_flush_lazy_mmu_mode();
+
+ return (void*) vaddr;
+}
+
+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);
+}
+
+EXPORT_SYMBOL(kmap);
+EXPORT_SYMBOL(kunmap);
+EXPORT_SYMBOL(kmap_atomic);
+EXPORT_SYMBOL(kunmap_atomic);
+EXPORT_SYMBOL(kmap_atomic_to_page);