[Xen-changelog] [xen stable-4.6] xen/bitops: Introduce GENMASK to generate mask

[patchbot@xxxxxxx]

commit e7cb648d4db185f9fc69e7ca570f79e39180b11a
Author:     Julien Grall <julien.grall@xxxxxxx>
AuthorDate: Fri Apr 22 16:58:32 2016 +0100
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Tue May 17 11:17:16 2016 +0100

    xen/bitops: Introduce GENMASK to generate mask
    
    The code has been imported from the header include/linux/bitops.h in
    Linux v4.6-rc3.
    
    Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
    Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/include/xen/bitops.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h
index cb56f24..bd0883a 100644
--- a/xen/include/xen/bitops.h
+++ b/xen/include/xen/bitops.h
@@ -3,6 +3,14 @@
 #include <asm/types.h>
 
 /*
+ * Create a contiguous bitmask starting at bit position @l and ending at
+ * position @h. For example
+ * GENMASK(30, 21) gives us the 32bit vector 0x01fe00000.
+ */
+#define GENMASK(h, l) \
+    (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
+
+/*
  * ffs: find first bit set. This is defined the same way as
  * the libc and compiler builtin ffs routines, therefore
  * differs in spirit from the above ffz (man ffs).
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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