linux/bits.h: make BIT(), GENMASK(), and friends available in assembly

2019-07-17T02:23:22Z

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 Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

locking/atomics, asm-generic: Move some macros from to a new file

2018-06-21T10:52:11Z

In preparation for implementing the asm-generic atomic bitops in terms of atomic_long_*(), we need to prevent implementations from pulling in . A common reason for this include is for the BITS_PER_BYTE definition, so move this and some other BIT() and masking macros into a new header file, . Signed-off-by: Will Deacon Acked-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-arm-kernel@lists.infradead.org Cc: yamada.masahiro@socionext.com Link: https://lore.kernel.org/lkml/1529412794-17720-4-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar

kernel/include/linux/bits.h, branch linux-5.4.y

linux/bits.h: make BIT(), GENMASK(), and friends available in assembly

locking/atomics, asm-generic: Move some macros from to a new file