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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2012-09-04 15:37:55 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2012-09-26 15:45:08 +0200
commit34cda99260247873df53ae00885fb0f426b149a5 (patch)
treeaf5b82520a729e3c68493b247ebb99a7ae65ca1a
parent25502f0015a8d6dd4bb34336ddb3eac6b1a55317 (diff)
downloadop-kernel-dev-34cda99260247873df53ae00885fb0f426b149a5.zip
op-kernel-dev-34cda99260247873df53ae00885fb0f426b149a5.tar.gz
s390/mm: implement __get_user_pages_fast()
This patch introduces the __get_user_pages_fast() function on s390, which will be needed with CONFIG_TRANSPARENT_HUGEPAGE and futex. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
-rw-r--r--arch/s390/mm/gup.c37
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index 65cb06e..eeaf802 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -154,6 +154,43 @@ static inline int gup_pud_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
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, pgd;
+ 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,
+ (void __user *)start, len)))
+ return 0;
+
+ local_irq_save(flags);
+ pgdp = pgd_offset(mm, addr);
+ do {
+ pgd = *pgdp;
+ barrier();
+ next = pgd_addr_end(addr, end);
+ if (pgd_none(pgd))
+ break;
+ if (!gup_pud_range(pgdp, pgd, addr, next, write, pages, &nr))
+ break;
+ } while (pgdp++, addr = next, addr != end);
+ local_irq_restore(flags);
+
+ return nr;
+}
+
/**
* get_user_pages_fast() - pin user pages in memory
* @start: starting user address
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