diff options
Diffstat (limited to 'include/linux/bits.h')
| -rw-r--r-- | include/linux/bits.h | 80 |
1 files changed, 58 insertions, 22 deletions
diff --git a/include/linux/bits.h b/include/linux/bits.h index 14fd0ca9a6cd..a40cc861b3a7 100644 --- a/include/linux/bits.h +++ b/include/linux/bits.h @@ -2,16 +2,15 @@ #ifndef __LINUX_BITS_H #define __LINUX_BITS_H -#include <linux/const.h> #include <vdso/bits.h> #include <uapi/linux/bits.h> -#include <asm/bitsperlong.h> #define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG)) #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) /* * Create a contiguous bitmask starting at bit position @l and ending at @@ -19,35 +18,72 @@ * 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/build_bug.h> #include <linux/compiler.h> +#include <linux/overflow.h> + #define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h))) -#else + /* - * BUILD_BUG_ON_ZERO is not available in h files included from asm files, - * disable the input check if that is the case. + * 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_INPUT_CHECK(h, l) 0 -#endif +#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_INPUT_CHECK(h, l) + __GENMASK(h, l)) -#define GENMASK_ULL(h, l) \ - (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l)) +#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) -#if !defined(__ASSEMBLY__) /* - * Missing asm support + * Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE(). The + * following examples generate compiler warnings due to -Wshift-count-overflow: * - * __GENMASK_U128() depends on _BIT128() which would not work - * in the asm code, as it shifts an 'unsigned __int128' data - * type instead of direct representation of 128 bit constants - * such as long and unsigned long. The fundamental problem is - * that a 128 bit constant will get silently truncated by the - * gcc compiler. + * - BIT_U8(8) + * - BIT_U32(-1) + * - BIT_U32(40) */ -#define GENMASK_U128(h, l) \ - (GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l)) -#endif +#define BIT_INPUT_CHECK(type, nr) \ + BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type))) + +#define BIT_TYPE(type, nr) ((type)(BIT_INPUT_CHECK(type, nr) + BIT_ULL(nr))) + +#define BIT_U8(nr) BIT_TYPE(u8, nr) +#define BIT_U16(nr) BIT_TYPE(u16, nr) +#define BIT_U32(nr) BIT_TYPE(u32, nr) +#define BIT_U64(nr) BIT_TYPE(u64, nr) + +#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 */ |