summaryrefslogtreecommitdiff
path: root/lib
diff options
context:
space:
mode:
authorYury Norov <yury.norov@gmail.com>2022-04-28 13:51:13 -0700
committerYury Norov <yury.norov@gmail.com>2022-06-03 06:52:58 -0700
commit0a97953fd2210d0ac8eb5c76f8bd08fb53b6d3d6 (patch)
tree6e885d7e9e651c08d3db29539df803d48f7ae193 /lib
parente041e0ac53dd52d2d201aa87edc3adaca1085299 (diff)
lib: add bitmap_{from,to}_arr64
Manipulating 64-bit arrays with bitmap functions is potentially dangerous because on 32-bit BE machines the order of halfwords doesn't match. Another issue is that compiler may throw a warning about out-of-boundary access. This patch adds bitmap_{from,to}_arr64 functions in addition to existing bitmap_{from,to}_arr32. CC: Alexander Gordeev <agordeev@linux.ibm.com> CC: Andy Shevchenko <andriy.shevchenko@linux.intel.com> CC: Christian Borntraeger <borntraeger@linux.ibm.com> CC: Claudio Imbrenda <imbrenda@linux.ibm.com> CC: David Hildenbrand <david@redhat.com> CC: Heiko Carstens <hca@linux.ibm.com> CC: Janosch Frank <frankja@linux.ibm.com> CC: Rasmus Villemoes <linux@rasmusvillemoes.dk> CC: Sven Schnelle <svens@linux.ibm.com> CC: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Yury Norov <yury.norov@gmail.com>
Diffstat (limited to 'lib')
-rw-r--r--lib/bitmap.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 8ebe508580ea..4061a5dd2bc6 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -1512,5 +1512,59 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
}
EXPORT_SYMBOL(bitmap_to_arr32);
+#endif
+
+#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN)
+/**
+ * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap
+ * @bitmap: array of unsigned longs, the destination bitmap
+ * @buf: array of u64 (in host byte order), the source bitmap
+ * @nbits: number of bits in @bitmap
+ */
+void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits)
+{
+ int n;
+
+ for (n = nbits; n > 0; n -= 64) {
+ u64 val = *buf++;
+
+ *bitmap++ = val;
+ if (n > 32)
+ *bitmap++ = val >> 32;
+ }
+
+ /*
+ * Clear tail bits in the last word beyond nbits.
+ *
+ * Negative index is OK because here we point to the word next
+ * to the last word of the bitmap, except for nbits == 0, which
+ * is tested implicitly.
+ */
+ if (nbits % BITS_PER_LONG)
+ bitmap[-1] &= BITMAP_LAST_WORD_MASK(nbits);
+}
+EXPORT_SYMBOL(bitmap_from_arr64);
+
+/**
+ * bitmap_to_arr64 - copy the contents of bitmap to a u64 array of bits
+ * @buf: array of u64 (in host byte order), the dest bitmap
+ * @bitmap: array of unsigned longs, the source bitmap
+ * @nbits: number of bits in @bitmap
+ */
+void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits)
+{
+ const unsigned long *end = bitmap + BITS_TO_LONGS(nbits);
+ while (bitmap < end) {
+ *buf = *bitmap++;
+ if (bitmap < end)
+ *buf |= (u64)(*bitmap++) << 32;
+ buf++;
+ }
+
+ /* Clear tail bits in the last element of array beyond nbits. */
+ if (nbits % 64)
+ buf[-1] &= GENMASK_ULL(nbits % 64, 0);
+}
+EXPORT_SYMBOL(bitmap_to_arr64);
#endif