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-rw-r--r--mm/highmem.c86
1 files changed, 75 insertions, 11 deletions
diff --git a/mm/highmem.c b/mm/highmem.c
index b32b70cdaed6..123bcd3ed4f2 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -44,6 +44,66 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
*/
#ifdef CONFIG_HIGHMEM
+/*
+ * Architecture with aliasing data cache may define the following family of
+ * helper functions in its asm/highmem.h to control cache color of virtual
+ * addresses where physical memory pages are mapped by kmap.
+ */
+#ifndef get_pkmap_color
+
+/*
+ * Determine color of virtual address where the page should be mapped.
+ */
+static inline unsigned int get_pkmap_color(struct page *page)
+{
+ return 0;
+}
+#define get_pkmap_color get_pkmap_color
+
+/*
+ * Get next index for mapping inside PKMAP region for page with given color.
+ */
+static inline unsigned int get_next_pkmap_nr(unsigned int color)
+{
+ static unsigned int last_pkmap_nr;
+
+ last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
+ return last_pkmap_nr;
+}
+
+/*
+ * Determine if page index inside PKMAP region (pkmap_nr) of given color
+ * has wrapped around PKMAP region end. When this happens an attempt to
+ * flush all unused PKMAP slots is made.
+ */
+static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
+{
+ return pkmap_nr == 0;
+}
+
+/*
+ * Get the number of PKMAP entries of the given color. If no free slot is
+ * found after checking that many entries, kmap will sleep waiting for
+ * someone to call kunmap and free PKMAP slot.
+ */
+static inline int get_pkmap_entries_count(unsigned int color)
+{
+ return LAST_PKMAP;
+}
+
+/*
+ * Get head of a wait queue for PKMAP entries of the given color.
+ * Wait queues for different mapping colors should be independent to avoid
+ * unnecessary wakeups caused by freeing of slots of other colors.
+ */
+static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
+{
+ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
+
+ return &pkmap_map_wait;
+}
+#endif
+
unsigned long totalhigh_pages __read_mostly;
EXPORT_SYMBOL(totalhigh_pages);
@@ -68,13 +128,10 @@ unsigned int nr_free_highpages (void)
}
static int pkmap_count[LAST_PKMAP];
-static unsigned int last_pkmap_nr;
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
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
@@ -161,15 +218,17 @@ static inline unsigned long map_new_virtual(struct page *page)
{
unsigned long vaddr;
int count;
+ unsigned int last_pkmap_nr;
+ unsigned int color = get_pkmap_color(page);
start:
- count = LAST_PKMAP;
+ count = get_pkmap_entries_count(color);
/* Find an empty entry */
for (;;) {
- last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
- if (!last_pkmap_nr) {
+ last_pkmap_nr = get_next_pkmap_nr(color);
+ if (no_more_pkmaps(last_pkmap_nr, color)) {
flush_all_zero_pkmaps();
- count = LAST_PKMAP;
+ count = get_pkmap_entries_count(color);
}
if (!pkmap_count[last_pkmap_nr])
break; /* Found a usable entry */
@@ -181,12 +240,14 @@ start:
*/
{
DECLARE_WAITQUEUE(wait, current);
+ wait_queue_head_t *pkmap_map_wait =
+ get_pkmap_wait_queue_head(color);
__set_current_state(TASK_UNINTERRUPTIBLE);
- add_wait_queue(&pkmap_map_wait, &wait);
+ add_wait_queue(pkmap_map_wait, &wait);
unlock_kmap();
schedule();
- remove_wait_queue(&pkmap_map_wait, &wait);
+ remove_wait_queue(pkmap_map_wait, &wait);
lock_kmap();
/* Somebody else might have mapped it while we slept */
@@ -274,6 +335,8 @@ void kunmap_high(struct page *page)
unsigned long nr;
unsigned long flags;
int need_wakeup;
+ unsigned int color = get_pkmap_color(page);
+ wait_queue_head_t *pkmap_map_wait;
lock_kmap_any(flags);
vaddr = (unsigned long)page_address(page);
@@ -299,13 +362,14 @@ void kunmap_high(struct page *page)
* no need for the wait-queue-head's lock. Simply
* test if the queue is empty.
*/
- need_wakeup = waitqueue_active(&pkmap_map_wait);
+ pkmap_map_wait = get_pkmap_wait_queue_head(color);
+ need_wakeup = waitqueue_active(pkmap_map_wait);
}
unlock_kmap_any(flags);
/* do wake-up, if needed, race-free outside of the spin lock */
if (need_wakeup)
- wake_up(&pkmap_map_wait);
+ wake_up(pkmap_map_wait);
}
EXPORT_SYMBOL(kunmap_high);