@@ -6,7 +6,7 @@ obj-y := dma-mapping.o extable.o fault.o init.o \
iomap.o
obj-$(CONFIG_MMU) += fault-armv.o flush.o idmap.o ioremap.o \
- mmap.o pgd.o mmu.o
+ mmap.o pgd.o mmu.o gup.o
ifneq ($(CONFIG_MMU),y)
obj-y += nommu.o
new file mode 100644
@@ -0,0 +1,204 @@
+/*
+ * linux/arch/arm/mm/gup.c - Lockless get_user_pages_fast for arm
+ *
+ * Copyright (c) 2013 Samsung Electronics Co., Ltd.
+ * http://www.samsung.com
+ * Author : Chanho Park <chanho61.park@samsung.com>
+ *
+ * This code is written on reference from the x86 and PowerPC versions, by:
+ *
+ * Copyright (C) 2008 Nick Piggin
+ * Copyright (C) 2008 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/rwsem.h>
+#include <asm/pgtable.h>
+
+/*
+ * The performance critical leaf functions are made noinline otherwise gcc
+ * inlines everything into a single function which results in too much
+ * register pressure.
+ */
+static noinline int gup_pte_range(pmd_t *pmdp, unsigned long addr,
+ unsigned long end, int write, struct page **pages, int *nr)
+{
+ pte_t *ptep, pte;
+
+ ptep = pte_offset_kernel(pmdp, addr);
+ do {
+ struct page *page;
+
+ pte = *ptep;
+
+ if (!pte_present_user(pte) || (write && !pte_write(pte)))
+ return 0;
+
+ VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+ page = pte_page(pte);
+
+ if (!page_cache_get_speculative(page))
+ return 0;
+
+ pages[*nr] = page;
+ (*nr)++;
+
+ } while (ptep++, addr += PAGE_SIZE, addr != end);
+
+ return 1;
+}
+
+static int gup_pmd_range(pud_t *pudp, unsigned long addr, unsigned long end,
+ int write, struct page **pages, int *nr)
+{
+ unsigned long next;
+ pmd_t *pmdp;
+
+ pmdp = pmd_offset(pudp, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none(*pmdp) || pmd_bad(*pmdp))
+ return 0;
+ else if (!gup_pte_range(pmdp, addr, next, write, pages, nr))
+ return 0;
+ } while (pmdp++, addr = next, addr != end);
+
+ return 1;
+}
+
+static int gup_pud_range(pgd_t *pgdp, unsigned long addr, unsigned long end,
+ int write, struct page **pages, int *nr)
+{
+ unsigned long next;
+ pud_t *pudp;
+
+ pudp = pud_offset(pgdp, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none(*pudp))
+ return 0;
+ else if (!gup_pmd_range(pudp, addr, next, write, pages, nr))
+ return 0;
+ } while (pudp++, addr = next, addr != end);
+
+ return 1;
+}
+
+/*
+ * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
+ * back to the regular GUP.
+ */
+int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
+ struct page **pages)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long addr, len, end;
+ unsigned long next, flags;
+ pgd_t *pgdp;
+ int nr = 0;
+
+ start &= PAGE_MASK;
+ addr = start;
+ len = (unsigned long) nr_pages << PAGE_SHIFT;
+ end = start + len;
+
+ if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
+ start, len)))
+ return 0;
+
+ /*
+ * This doesn't prevent pagetable teardown, but does prevent
+ * the pagetables from being freed on arm.
+ *
+ * So long as we atomically load page table pointers versus teardown,
+ * we can follow the address down to the the page and take a ref on it.
+ */
+ local_irq_save(flags);
+
+ pgdp = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none(*pgdp))
+ break;
+ else if (!gup_pud_range(pgdp, addr, next, write, pages, &nr))
+ break;
+ } while (pgdp++, addr = next, addr != end);
+
+ local_irq_restore(flags);
+
+ return nr;
+}
+
+int get_user_pages_fast(unsigned long start, int nr_pages, int write,
+ struct page **pages)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long addr, len, end;
+ unsigned long next;
+ pgd_t *pgdp;
+ int nr = 0;
+
+ start &= PAGE_MASK;
+ addr = start;
+ len = (unsigned long) nr_pages << PAGE_SHIFT;
+ end = start + len;
+
+ if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
+ start, len)))
+ goto slow_irqon;
+
+ /*
+ * This doesn't prevent pagetable teardown, but does prevent
+ * the pagetables from being freed on arm.
+ *
+ * So long as we atomically load page table pointers versus teardown,
+ * we can follow the address down to the the page and take a ref on it.
+ */
+ local_irq_disable();
+
+ pgdp = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none(*pgdp))
+ goto slow;
+ else if (!gup_pud_range(pgdp, addr, next, write, pages, &nr))
+ goto slow;
+ } while (pgdp++, addr = next, addr != end);
+
+ local_irq_enable();
+
+ VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
+ return nr;
+
+ {
+ int ret;
+
+slow:
+ local_irq_enable();
+slow_irqon:
+ /* Try to get the remaining pages with get_user_pages */
+ start += nr << PAGE_SHIFT;
+ pages += nr;
+
+ down_read(&mm->mmap_sem);
+ ret = get_user_pages(current, mm, start,
+ (end - start) >> PAGE_SHIFT, write, 0, pages, NULL);
+ up_read(&mm->mmap_sem);
+
+ /* Have to be a bit careful with return values */
+ if (nr > 0) {
+ if (ret < 0)
+ ret = nr;
+ else
+ ret += nr;
+ }
+
+ return ret;
+ }
+}