1 files changed, 91 insertions, 38 deletions

diff --git a/mm/highmem.c b/mm/highmem.c
index 7da4a7b6af1..b32b70cdaed 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -17,7 +17,7 @@
  */
 
 #include <linux/mm.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/swap.h>
 #include <linux/bio.h>
 #include <linux/pagemap.h>
@@ -26,9 +26,14 @@
 #include <linux/init.h>
 #include <linux/hash.h>
 #include <linux/highmem.h>
-#include <linux/blktrace_api.h>
+#include <linux/kgdb.h>
 #include <asm/tlbflush.h>
 
+
+#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
+DEFINE_PER_CPU(int, __kmap_atomic_idx);
+#endif
+
 /*
  * Virtual_count is not a pure "count".
  *  0 means that it is not mapped, and has not been mapped
@@ -40,6 +45,10 @@
 #ifdef CONFIG_HIGHMEM
 
 unsigned long totalhigh_pages __read_mostly;
+EXPORT_SYMBOL(totalhigh_pages);
+
+
+EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
 
 unsigned int nr_free_highpages (void)
 {
@@ -66,9 +75,42 @@ pte_t * pkmap_page_table;
 
 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
 
+/*
+ * Most architectures have no use for kmap_high_get(), so let's abstract
+ * the disabling of IRQ out of the locking in that case to save on a
+ * potential useless overhead.
+ */
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+#define lock_kmap()             spin_lock_irq(&kmap_lock)
+#define unlock_kmap()           spin_unlock_irq(&kmap_lock)
+#define lock_kmap_any(flags)    spin_lock_irqsave(&kmap_lock, flags)
+#define unlock_kmap_any(flags)  spin_unlock_irqrestore(&kmap_lock, flags)
+#else
+#define lock_kmap()             spin_lock(&kmap_lock)
+#define unlock_kmap()           spin_unlock(&kmap_lock)
+#define lock_kmap_any(flags)    \
+		do { spin_lock(&kmap_lock); (void)(flags); } while (0)
+#define unlock_kmap_any(flags)  \
+		do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
+#endif
+
+struct page *kmap_to_page(void *vaddr)
+{
+	unsigned long addr = (unsigned long)vaddr;
+
+	if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
+		int i = PKMAP_NR(addr);
+		return pte_page(pkmap_page_table[i]);
+	}
+
+	return virt_to_page(addr);
+}
+EXPORT_SYMBOL(kmap_to_page);
+
 static void flush_all_zero_pkmaps(void)
 {
 	int i;
+	int need_flush = 0;
 
 	flush_cache_kmaps();
 
@@ -96,12 +138,13 @@ static void flush_all_zero_pkmaps(void)
 		 * So no dangers, even with speculative execution.
 		 */
 		page = pte_page(pkmap_page_table[i]);
-		pte_clear(&init_mm, (unsigned long)page_address(page),
-			  &pkmap_page_table[i]);
+		pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);
 
 		set_page_address(page, NULL);
+		need_flush = 1;
 	}
-	flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
+	if (need_flush)
+		flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
 }
 
 /**
@@ -109,9 +152,9 @@ static void flush_all_zero_pkmaps(void)
  */
 void kmap_flush_unused(void)
 {
-	spin_lock(&kmap_lock);
+	lock_kmap();
 	flush_all_zero_pkmaps();
-	spin_unlock(&kmap_lock);
+	unlock_kmap();
 }
 
 static inline unsigned long map_new_virtual(struct page *page)
@@ -141,10 +184,10 @@ start:
 
 			__set_current_state(TASK_UNINTERRUPTIBLE);
 			add_wait_queue(&pkmap_map_wait, &wait);
-			spin_unlock(&kmap_lock);
+			unlock_kmap();
 			schedule();
 			remove_wait_queue(&pkmap_map_wait, &wait);
-			spin_lock(&kmap_lock);
+			lock_kmap();
 
 			/* Somebody else might have mapped it while we slept */
 			if (page_address(page))
@@ -180,29 +223,59 @@ void *kmap_high(struct page *page)
 	 * For highmem pages, we can't trust "virtual" until
 	 * after we have the lock.
 	 */
-	spin_lock(&kmap_lock);
+	lock_kmap();
 	vaddr = (unsigned long)page_address(page);
 	if (!vaddr)
 		vaddr = map_new_virtual(page);
 	pkmap_count[PKMAP_NR(vaddr)]++;
 	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
-	spin_unlock(&kmap_lock);
+	unlock_kmap();
 	return (void*) vaddr;
 }
 
 EXPORT_SYMBOL(kmap_high);
 
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+/**
+ * kmap_high_get - pin a highmem page into memory
+ * @page: &struct page to pin
+ *
+ * Returns the page's current virtual memory address, or NULL if no mapping
+ * exists.  If and only if a non null address is returned then a
+ * matching call to kunmap_high() is necessary.
+ *
+ * This can be called from any context.
+ */
+void *kmap_high_get(struct page *page)
+{
+	unsigned long vaddr, flags;
+
+	lock_kmap_any(flags);
+	vaddr = (unsigned long)page_address(page);
+	if (vaddr) {
+		BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
+		pkmap_count[PKMAP_NR(vaddr)]++;
+	}
+	unlock_kmap_any(flags);
+	return (void*) vaddr;
+}
+#endif
+
 /**
- * kunmap_high - map a highmem page into memory
+ * kunmap_high - unmap a highmem page into memory
  * @page: &struct page to unmap
+ *
+ * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
+ * only from user context.
  */
 void kunmap_high(struct page *page)
 {
 	unsigned long vaddr;
 	unsigned long nr;
+	unsigned long flags;
 	int need_wakeup;
 
-	spin_lock(&kmap_lock);
+	lock_kmap_any(flags);
 	vaddr = (unsigned long)page_address(page);
 	BUG_ON(!vaddr);
 	nr = PKMAP_NR(vaddr);
@@ -228,7 +301,7 @@ void kunmap_high(struct page *page)
 		 */
 		need_wakeup = waitqueue_active(&pkmap_map_wait);
 	}
-	spin_unlock(&kmap_lock);
+	unlock_kmap_any(flags);
 
 	/* do wake-up, if needed, race-free outside of the spin lock */
 	if (need_wakeup)
@@ -251,11 +324,7 @@ struct page_address_map {
 	struct list_head list;
 };
 
-/*
- * page_address_map freelist, allocated from page_address_maps.
- */
-static struct list_head page_address_pool;	/* freelist */
-static spinlock_t pool_lock;			/* protects page_address_pool */
+static struct page_address_map page_address_maps[LAST_PKMAP];
 
 /*
  * Hash table bucket
@@ -265,7 +334,7 @@ static struct page_address_slot {
 	spinlock_t lock;			/* Protect this bucket's list */
 } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
 
-static struct page_address_slot *page_slot(struct page *page)
+static struct page_address_slot *page_slot(const struct page *page)
 {
 	return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
 }
@@ -276,7 +345,7 @@ static struct page_address_slot *page_slot(struct page *page)
  *
  * Returns the page's virtual address.
  */
-void *page_address(struct page *page)
+void *page_address(const struct page *page)
 {
 	unsigned long flags;
 	void *ret;
@@ -320,14 +389,7 @@ void set_page_address(struct page *page, void *virtual)
 
 	pas = page_slot(page);
 	if (virtual) {		/* Add */
-		BUG_ON(list_empty(&page_address_pool));
-
-		spin_lock_irqsave(&pool_lock, flags);
-		pam = list_entry(page_address_pool.next,
-				struct page_address_map, list);
-		list_del(&pam->list);
-		spin_unlock_irqrestore(&pool_lock, flags);
-
+		pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
 		pam->page = page;
 		pam->virtual = virtual;
 
@@ -340,9 +402,6 @@ void set_page_address(struct page *page, void *virtual)
 			if (pam->page == page) {
 				list_del(&pam->list);
 				spin_unlock_irqrestore(&pas->lock, flags);
-				spin_lock_irqsave(&pool_lock, flags);
-				list_add_tail(&pam->list, &page_address_pool);
-				spin_unlock_irqrestore(&pool_lock, flags);
 				goto done;
 			}
 		}
@@ -352,20 +411,14 @@ done:
 	return;
 }
 
-static struct page_address_map page_address_maps[LAST_PKMAP];
-
 void __init page_address_init(void)
 {
 	int i;
 
-	INIT_LIST_HEAD(&page_address_pool);
-	for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
-		list_add(&page_address_maps[i].list, &page_address_pool);
 	for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
 		INIT_LIST_HEAD(&page_address_htable[i].lh);
 		spin_lock_init(&page_address_htable[i].lock);
 	}
-	spin_lock_init(&pool_lock);
 }
 
 #endif	/* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */