This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / arch / i386 / mm / highmem-xen.c

diff --git a/arch/i386/mm/highmem-xen.c b/arch/i386/mm/highmem-xen.c
new file mode 100644 (file)
index 0000000..23f0e1b
--- /dev/null
+++ b/arch/i386/mm/highmem-xen.c
@@ -0,0 +1,133 @@
+#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.
+ */
+static void *__kmap_atomic(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 */
+       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_at_sync(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
+
+       return (void*) vaddr;
+}
+
+void *kmap_atomic(struct page *page, enum km_type type)
+{
+       return __kmap_atomic(page, type, kmap_prot);
+}
+
+/* Same as kmap_atomic but with PAGE_KERNEL_RO page protection. */
+void *kmap_atomic_pte(struct page *page, enum km_type type)
+{
+       return __kmap_atomic(page, type, PAGE_KERNEL_RO);
+}
+
+void kunmap_atomic(void *kvaddr, enum km_type type)
+{
+#if defined(CONFIG_DEBUG_HIGHMEM) || defined(CONFIG_XEN)
+       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;
+       }
+#endif
+
+#if defined(CONFIG_DEBUG_HIGHMEM)
+       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);
+#elif defined(CONFIG_XEN)
+       /*
+        * We must ensure there are no dangling pagetable references when
+        * returning memory to Xen (decrease_reservation).
+        * XXX TODO: We could make this faster by only zapping when
+        * kmap_flush_unused is called but that is trickier and more invasive.
+        */
+       pte_clear(&init_mm, vaddr, kmap_pte-idx);
+#endif
+
+       dec_preempt_count();
+       preempt_check_resched();
+}
+
+/* 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;
+
+       inc_preempt_count();
+
+       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));
+       __flush_tlb_one(vaddr);
+
+       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);