@@ -6,7 +6,7 @@ obj-y := dma-mapping.o extable.o fault.o init.o \
iomap.o
obj-$(CONFIG_MMU) += fault-armv.o flush.o idmap.o ioremap.o \
- mmap.o pgd.o mmu.o pageattr.o
+ mmap.o pgd.o mmu.o pageattr.o gup.o
ifneq ($(CONFIG_MMU),y)
obj-y += nommu.o
new file mode 100644
@@ -0,0 +1,90 @@
+/*
+ * Lockless get_user_pages_fast for ARM
+ *
+ * Copyright (C) 2014 Lytro, Inc.
+ */
+
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/vmstat.h>
+#include <linux/highmem.h>
+#include <linux/swap.h>
+
+#include <asm/pgtable.h>
+
+struct gup_private_data {
+ int nr;
+ struct page **pages;
+ int write;
+};
+
+static int gup_pte_entry(pte_t *ptep, unsigned long start,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct gup_private_data *private_data =
+ (struct gup_private_data *)walk->private;
+ struct page * page;
+ pte_t pte = *ptep;
+ if (!pte_present(pte) ||
+ pte_special(pte) ||
+ (private_data->write && !pte_write(pte)))
+ {
+ return private_data->nr;
+ }
+ page = pte_page(pte);
+ get_page(page);
+ private_data->pages[private_data->nr++] = page;
+ return 0;
+}
+
+static int gup_pte_hole_entry(unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct gup_private_data *private_data =
+ (struct gup_private_data *)walk->private;
+ return private_data->nr;
+}
+
+
+int get_user_pages_fast(unsigned long start, int nr_pages, int write,
+ struct page **pages)
+{
+ struct mm_struct *mm = current->mm;
+ int ret;
+ unsigned long page_addr = (start & PAGE_MASK);
+ int nr = 0;
+
+ struct gup_private_data private_data = {
+ .nr = 0,
+ .pages = pages,
+ .write = write
+ };
+
+ struct mm_walk gup_walk = {
+ .pte_entry = gup_pte_entry,
+ .pte_hole = gup_pte_hole_entry,
+ .mm = mm,
+ .private = (void *)&private_data
+ };
+
+ ret = walk_page_range(page_addr,
+ page_addr + nr_pages * PAGE_SIZE,
+ &gup_walk);
+ nr = ret ? ret : nr_pages;
+
+ if (nr == nr_pages)
+ {
+ return nr;
+ }
+ else
+ {
+ page_addr += (nr << PAGE_SHIFT);
+ }
+
+ down_read(&mm->mmap_sem);
+ ret = get_user_pages(current, mm, page_addr,
+ nr_pages - nr, write, 0, pages + nr, NULL);
+ up_read(&mm->mmap_sem);
+
+ return (ret < 0) ? nr : (ret + nr);
+}
\ No newline at end of file