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Fix build on old userspace

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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2025-09-17 12:27:30 -04:00
parent b6bb1e2a11
commit 1c64faafe7
1 changed files with 70 additions and 0 deletions
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include/linux/bits.h Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_BITS_H
#define __LINUX_BITS_H
//#include <vdso/bits.h>
//#include <uapi/linux/bits.h>
#define BIT_WORD(nr) ((nr) / BITS_PER_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
#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (__BITS_PER_LONG - 1 - (h))))
/*
* Create a contiguous bitmask starting at bit position @l and ending at
* position @h. For example
* GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
*/
#if !defined(__ASSEMBLY__)
/*
* Missing asm support
*
* GENMASK_U*() and BIT_U*() depend on BITS_PER_TYPE() which relies on sizeof(),
* something not available in asm. Nevertheless, fixed width integers is a C
* concept. Assembly code can rely on the long and long long versions instead.
*/
#include <linux/compiler.h>
#include <linux/overflow.h>
#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))
/*
* Generate a mask for the specified type @t. Additional checks are made to
* guarantee the value returned fits in that type, relying on
* -Wshift-count-overflow compiler check to detect incompatible arguments.
* For example, all these create build errors or warnings:
*
* - GENMASK(15, 20): wrong argument order
* - GENMASK(72, 15): doesn't fit unsigned long
* - GENMASK_U32(33, 15): doesn't fit in a u32
*/
#define GENMASK_TYPE(t, h, l) \
((t)(GENMASK_INPUT_CHECK(h, l) + \
(type_max(t) << (l) & \
type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h)))))
#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
#define GENMASK_ULL(h, l) GENMASK_TYPE(unsigned long long, h, l)
#define GENMASK_U8(h, l) GENMASK_TYPE(u8, h, l)
#define GENMASK_U16(h, l) GENMASK_TYPE(u16, h, l)
#define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l)
#define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l)
#define GENMASK_U128(h, l) GENMASK_TYPE(u128, h, l)
#else /* defined(__ASSEMBLY__) */
/*
* BUILD_BUG_ON_ZERO is not available in h files included from asm files,
* disable the input check if that is the case.
*/
#define GENMASK(h, l) __GENMASK(h, l)
#define GENMASK_ULL(h, l) __GENMASK_ULL(h, l)
#endif /* !defined(__ASSEMBLY__) */
#endif /* __LINUX_BITS_H */