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authorMasahiro Yamada <yamada.masahiro@socionext.com>2019-07-17 02:26:57 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-17 05:23:22 +0300
commit95b980d62d52c4c1768ee719e8db3efe27ef52b2 (patch)
treef358ac87dee827a037aa8fd538b328b347490108 /include/linux/bits.h
parent65f50f255349959f15f2761abd17ead8530b2f33 (diff)
downloadlinux-95b980d62d52c4c1768ee719e8db3efe27ef52b2.tar.xz
linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
BIT(), GENMASK(), etc. are useful to define register bits of hardware. However, low-level code is often written in assembly, where they are not available due to the hard-coded 1UL, 0UL. In fact, in-kernel headers such as arch/arm64/include/asm/sysreg.h use _BITUL() instead of BIT() so that the register bit macros are available in assembly. Using macros in include/uapi/linux/const.h have two reasons: [1] For use in uapi headers We should use underscore-prefixed variants for user-space. [2] For use in assembly code Since _BITUL() uses UL(1) instead of 1UL, it can be used as an alternative of BIT(). For [2], it is pretty easy to change BIT() etc. for use in assembly. This allows to replace _BUTUL() in kernel-space headers with BIT(). Link: http://lkml.kernel.org/r/20190609153941.17249-1-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/bits.h')
-rw-r--r--include/linux/bits.h17
1 files changed, 10 insertions, 7 deletions
diff --git a/include/linux/bits.h b/include/linux/bits.h
index 2b7b532c1d51..669d69441a62 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -1,13 +1,15 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_BITS_H
#define __LINUX_BITS_H
+
+#include <linux/const.h>
#include <asm/bitsperlong.h>
-#define BIT(nr) (1UL << (nr))
-#define BIT_ULL(nr) (1ULL << (nr))
-#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
+#define BIT(nr) (UL(1) << (nr))
+#define BIT_ULL(nr) (ULL(1) << (nr))
+#define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG))
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
-#define BIT_ULL_MASK(nr) (1ULL << ((nr) % BITS_PER_LONG_LONG))
+#define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG))
#define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG)
#define BITS_PER_BYTE 8
@@ -17,10 +19,11 @@
* GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
*/
#define GENMASK(h, l) \
- (((~0UL) - (1UL << (l)) + 1) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
+ (((~UL(0)) - (UL(1) << (l)) + 1) & \
+ (~UL(0) >> (BITS_PER_LONG - 1 - (h))))
#define GENMASK_ULL(h, l) \
- (((~0ULL) - (1ULL << (l)) + 1) & \
- (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
+ (((~ULL(0)) - (ULL(1) << (l)) + 1) & \
+ (~ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
#endif /* __LINUX_BITS_H */