| 1 |
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| 2 | #ifndef __LINUX_BITS_H
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| 3 | #define __LINUX_BITS_H
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| 4 |
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| 5 | #include <vdso/bits.h>
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| 6 | #include <uapi/linux/bits.h>
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| 7 |
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| 8 | #define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG))
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| 9 | #define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
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| 10 | #define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG))
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| 11 | #define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG)
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| 12 | #define BITS_PER_BYTE 8
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| 13 | #define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
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| 14 |
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| 15 | |
| 16 | * Create a contiguous bitmask starting at bit position @l and ending at
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| 17 | * position @h. For example
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| 18 | * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
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| 19 |
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| 20 | #if !defined(__ASSEMBLER__)
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| 21 |
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| 22 | |
| 23 | * Missing asm support
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| 24 | *
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| 25 | * GENMASK_U*() and BIT_U*() depend on BITS_PER_TYPE() which relies on sizeof(),
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| 26 | * something not available in asm. Nevertheless, fixed width integers is a C
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| 27 | * concept. Assembly code can rely on the long and long long versions instead.
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| 28 |
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| 29 |
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| 30 | #include <linux/build_bug.h>
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| 31 | #include <linux/compiler.h>
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| 32 | #include <linux/overflow.h>
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| 33 |
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| 34 | #define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))
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| 35 |
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| 36 | |
| 37 | * Generate a mask for the specified type @t. Additional checks are made to
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| 38 | * guarantee the value returned fits in that type, relying on
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| 39 | * -Wshift-count-overflow compiler check to detect incompatible arguments.
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| 40 | * For example, all these create build errors or warnings:
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| 41 | *
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| 42 | * - GENMASK(15, 20): wrong argument order
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| 43 | * - GENMASK(72, 15): doesn't fit unsigned long
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| 44 | * - GENMASK_U32(33, 15): doesn't fit in a u32
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| 45 |
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| 46 | #define GENMASK_TYPE(t, h, l) \
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| 47 | ((t)(GENMASK_INPUT_CHECK(h, l) + \
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| 48 | (type_max(t) << (l) & \
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| 49 | type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h)))))
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| 50 |
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| 51 | #define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l)
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| 52 | #define GENMASK_ULL(h, l) GENMASK_TYPE(unsigned long long, h, l)
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| 53 |
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| 54 | #define GENMASK_U8(h, l) GENMASK_TYPE(u8, h, l)
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| 55 | #define GENMASK_U16(h, l) GENMASK_TYPE(u16, h, l)
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| 56 | #define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l)
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| 57 | #define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l)
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| 58 | #define GENMASK_U128(h, l) GENMASK_TYPE(u128, h, l)
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| 59 |
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| 60 | |
| 61 | * Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE(). The
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| 62 | * following examples generate compiler warnings due to -Wshift-count-overflow:
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| 63 | *
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| 64 | * - BIT_U8(8)
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| 65 | * - BIT_U32(-1)
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| 66 | * - BIT_U32(40)
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| 67 |
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| 68 | #define BIT_INPUT_CHECK(type, nr) \
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| 69 | BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type)))
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| 70 |
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| 71 | #define BIT_TYPE(type, nr) ((type)(BIT_INPUT_CHECK(type, nr) + BIT_ULL(nr)))
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| 72 |
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| 73 | #define BIT_U8(nr) BIT_TYPE(u8, nr)
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| 74 | #define BIT_U16(nr) BIT_TYPE(u16, nr)
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| 75 | #define BIT_U32(nr) BIT_TYPE(u32, nr)
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| 76 | #define BIT_U64(nr) BIT_TYPE(u64, nr)
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| 77 |
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| 78 | #else
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| 79 |
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| 80 | |
| 81 | * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
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| 82 | * disable the input check if that is the case.
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| 83 |
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| 84 | #define GENMASK(h, l) __GENMASK(h, l)
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| 85 | #define GENMASK_ULL(h, l) __GENMASK_ULL(h, l)
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| 86 |
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| 87 | #endif
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| 88 |
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| 89 | #endif
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