linux-kernel - [PATCH 09/21] bits: generalize BITMAP_{FIRST,LAST}_WORD

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Message-ID: <20251025163305.306787-2-yury.norov@gmail.com>
Date: Sat, 25 Oct 2025 12:32:51 -0400
From: "Yury Norov (NVIDIA)" <yury.norov@...il.com>
To: Linus Walleij <linus.walleij@...aro.org>,
	Lee Jones <lee@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Yury Norov <yury.norov@...il.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH 09/21] bits: generalize BITMAP_{FIRST,LAST}_WORD_MASK

The macros are helpful in many non-bitmap places too. Move them from
bitmap.h to bits.h.

Signed-off-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
---
 include/linux/bitmap.h | 7 +++++--
 include/linux/bits.h   | 8 ++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 595217b7a6e7..fbe2d12bceab 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -223,8 +223,11 @@ void bitmap_onto(unsigned long *dst, const unsigned long *orig,
 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
 		unsigned int sz, unsigned int nbits);
 
-#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
-#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
+#define BITMAP_FIRST_WORD_MASK(start) LAST_BITS(start)
+#define BITMAP_LAST_WORD_MASK(nbits) FIRST_BITS(nbits)
+
+#define BITMAP_FIRST_WORD_MASK_ULL(start) LAST_BITS(start)
+#define BITMAP_LAST_WORD_MASK_ULL(nbits) FIRST_BITS(nbits)
 
 #define bitmap_size(nbits)	(ALIGN(nbits, BITS_PER_LONG) / BITS_PER_BYTE)
 
diff --git a/include/linux/bits.h b/include/linux/bits.h
index c7c587e90e2d..0d2950b80a3b 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -5,6 +5,14 @@
 #include <vdso/bits.h>
 #include <uapi/linux/bits.h>
 
+/* Mask with first nbist set */
+#define FIRST_BITS(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
+#define FIRST_BITS_ULL(nbits) (~0ULL >> (-(nbits) & (BITS_PER_LONG_LONG - 1)))
+
+/* Mask with all bits before start unset */
+#define LAST_BITS(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
+#define LAST_BITS_ULL(start) (~0ULL << ((start) & (BITS_PER_LONG_LONG - 1)))
+
 #define BIT_MASK(nr)		(UL(1) << ((nr) % BITS_PER_LONG))
 #define BIT_WORD(nr)		((nr) / BITS_PER_LONG)
 #define BIT_ULL_MASK(nr)	(ULL(1) << ((nr) % BITS_PER_LONG_LONG))
-- 
2.43.0