[Xen-devel] [PATCH v5 01/30] bitops: add GENMASK_ULL

[Andre Przywara <andre.przywara@xxxxxxx>]

To safely handle 64-bit registers even on 32-bit systems, introduce
a GENMASK_ULL variant (lifted from Linux).
This adds a BITS_PER_LONG_LONG define as well.
Also fix a bug in the comment for the existing GENMASK variant.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/include/asm-arm/config.h | 2 ++
 xen/include/xen/bitops.h     | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index b2edf95..1f730ce 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -19,6 +19,8 @@
 #define BITS_PER_LONG (BYTES_PER_LONG << 3)
 #define POINTER_ALIGN BYTES_PER_LONG
 
+#define BITS_PER_LONG_LONG (sizeof (long long) * BITS_PER_BYTE)
+
 /* xen_ulong_t is always 64 bits */
 #define BITS_PER_XEN_ULONG 64
 
diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h
index bd0883a..9261e06 100644
--- a/xen/include/xen/bitops.h
+++ b/xen/include/xen/bitops.h
@@ -5,11 +5,14 @@
 /*
  * 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.
+ * GENMASK(30, 21) gives us the 32bit vector 0x7fe00000.
  */
 #define GENMASK(h, l) \
     (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
 
+#define GENMASK_ULL(h, l) \
+    (((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
+
 /*
  * ffs: find first bit set. This is defined the same way as
  * the libc and compiler builtin ffs routines, therefore
-- 
2.8.2


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