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Subject[PATCH 08/16] sparc64: define untagged_addr()
Date
Add a helper to untag a user pointer.  This is needed for ADI support
in get_user_pages_fast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
---
arch/sparc/include/asm/pgtable_64.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index f0dcf991d27f..1904782dcd39 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1076,6 +1076,28 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
}
#define io_remap_pfn_range io_remap_pfn_range

+static inline unsigned long untagged_addr(unsigned long start)
+{
+ if (adi_capable()) {
+ long addr = start;
+
+ /* If userspace has passed a versioned address, kernel
+ * will not find it in the VMAs since it does not store
+ * the version tags in the list of VMAs. Storing version
+ * tags in list of VMAs is impractical since they can be
+ * changed any time from userspace without dropping into
+ * kernel. Any address search in VMAs will be done with
+ * non-versioned addresses. Ensure the ADI version bits
+ * are dropped here by sign extending the last bit before
+ * ADI bits. IOMMU does not implement version tags.
+ */
+ return (addr << (long)adi_nbits()) >> (long)adi_nbits();
+ }
+
+ return start;
+}
+#define untagged_addr untagged_addr
+
#include <asm/tlbflush.h>
#include <asm-generic/pgtable.h>

--
2.20.1
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