| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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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 <linux/const.h> |
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| 6 | #include <vdso/bits.h> |
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| 7 | #include <uapi/linux/bits.h> |
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| 8 | #include <asm/bitsperlong.h> |
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| 9 | |
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| 10 | #define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG)) |
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| 11 | #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) |
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| 12 | #define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG)) |
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| 13 | #define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG) |
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| 14 | #define BITS_PER_BYTE 8 |
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| 15 | #define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) |
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| 16 | |
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| 17 | /* |
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| 18 | * Create a contiguous bitmask starting at bit position @l and ending at |
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| 19 | * position @h. For example |
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| 20 | * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000. |
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| 21 | */ |
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| 22 | #if !defined(__ASSEMBLY__) |
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| 23 | |
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| 24 | /* |
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| 25 | * Missing asm support |
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| 26 | * |
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| 27 | * GENMASK_U*() and BIT_U*() depend on BITS_PER_TYPE() which relies on sizeof(), |
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| 28 | * something not available in asm. Nevertheless, fixed width integers is a C |
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| 29 | * concept. Assembly code can rely on the long and long long versions instead. |
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| 30 | */ |
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| 31 | |
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| 32 | #include <linux/build_bug.h> |
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| 33 | #include <linux/compiler.h> |
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| 34 | #include <linux/overflow.h> |
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| 35 | |
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| 36 | #define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h))) |
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| 37 | |
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| 38 | /* |
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| 39 | * Generate a mask for the specified type @t. Additional checks are made to |
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| 40 | * guarantee the value returned fits in that type, relying on |
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| 41 | * -Wshift-count-overflow compiler check to detect incompatible arguments. |
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| 42 | * For example, all these create build errors or warnings: |
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| 43 | * |
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| 44 | * - GENMASK(15, 20): wrong argument order |
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| 45 | * - GENMASK(72, 15): doesn't fit unsigned long |
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| 46 | * - GENMASK_U32(33, 15): doesn't fit in a u32 |
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| 47 | */ |
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| 48 | #define GENMASK_TYPE(t, h, l) \ |
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| 49 | ((t)(GENMASK_INPUT_CHECK(h, l) + \ |
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| 50 | (type_max(t) << (l) & \ |
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| 51 | type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h))))) |
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| 52 | |
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| 53 | #define GENMASK_U8(h, l) GENMASK_TYPE(u8, h, l) |
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| 54 | #define GENMASK_U16(h, l) GENMASK_TYPE(u16, h, l) |
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| 55 | #define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l) |
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| 56 | #define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l) |
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| 57 | |
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| 58 | /* |
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| 59 | * Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE(). The |
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| 60 | * following examples generate compiler warnings due to -Wshift-count-overflow: |
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| 61 | * |
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| 62 | * - BIT_U8(8) |
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| 63 | * - BIT_U32(-1) |
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| 64 | * - BIT_U32(40) |
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| 65 | */ |
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| 66 | #define BIT_INPUT_CHECK(type, nr) \ |
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| 67 | BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type))) |
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| 68 | |
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| 69 | #define BIT_TYPE(type, nr) ((type)(BIT_INPUT_CHECK(type, nr) + BIT_ULL(nr))) |
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| 70 | |
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| 71 | #define BIT_U8(nr) BIT_TYPE(u8, nr) |
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| 72 | #define BIT_U16(nr) BIT_TYPE(u16, nr) |
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| 73 | #define BIT_U32(nr) BIT_TYPE(u32, nr) |
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| 74 | #define BIT_U64(nr) BIT_TYPE(u64, nr) |
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| 75 | |
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| 76 | #else /* defined(__ASSEMBLY__) */ |
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| 77 | |
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| 78 | /* |
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| 79 | * BUILD_BUG_ON_ZERO is not available in h files included from asm files, |
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| 80 | * disable the input check if that is the case. |
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| 81 | */ |
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| 82 | #define GENMASK_INPUT_CHECK(h, l) 0 |
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| 83 | |
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| 84 | #endif /* !defined(__ASSEMBLY__) */ |
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| 85 | |
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| 86 | #define GENMASK(h, l) \ |
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| 87 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l)) |
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| 88 | #define GENMASK_ULL(h, l) \ |
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| 89 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l)) |
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| 90 | |
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| 91 | #if !defined(__ASSEMBLY__) |
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| 92 | /* |
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| 93 | * Missing asm support |
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| 94 | * |
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| 95 | * __GENMASK_U128() depends on _BIT128() which would not work |
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| 96 | * in the asm code, as it shifts an 'unsigned __int128' data |
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| 97 | * type instead of direct representation of 128 bit constants |
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| 98 | * such as long and unsigned long. The fundamental problem is |
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| 99 | * that a 128 bit constant will get silently truncated by the |
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| 100 | * gcc compiler. |
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| 101 | */ |
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| 102 | #define GENMASK_U128(h, l) \ |
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| 103 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l)) |
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| 104 | #endif |
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| 105 | |
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| 106 | #endif /* __LINUX_BITS_H */ |
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| 107 | |
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