diff options
| -rw-r--r-- | include/linux/bitmap.h | 32 | ||||
| -rw-r--r-- | lib/test_bitmap.c | 47 |
2 files changed, 64 insertions, 15 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 5797ca6fdfe2..700cf5f67118 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -361,6 +361,38 @@ static inline int bitmap_parse(const char *buf, unsigned int buflen, } /* + * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap. + * + * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit + * integers in 32-bit environment, and 64-bit integers in 64-bit one. + * + * There are four combinations of endianness and length of the word in linux + * ABIs: LE64, BE64, LE32 and BE32. + * + * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in + * bitmaps and therefore don't require any special handling. + * + * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory + * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the + * other hand is represented as an array of 32-bit words and the position of + * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that + * word. For example, bit #42 is located at 10th position of 2nd word. + * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit + * values in memory as it usually does. But for BE we need to swap hi and lo + * words manually. + * + * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and + * lo parts of u64. For LE32 it does nothing, and for BE environment it swaps + * hi and lo words, as is expected by bitmap. + */ +#if __BITS_PER_LONG == 64 +#define BITMAP_FROM_U64(n) (n) +#else +#define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \ + ((unsigned long) ((u64)(n) >> 32)) +#endif + +/* * bitmap_from_u64 - Check and swap words within u64. * @mask: source bitmap * @dst: destination bitmap diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c index 431c97fb1aa0..599c6713f2a2 100644 --- a/lib/test_bitmap.c +++ b/lib/test_bitmap.c @@ -175,24 +175,41 @@ struct test_bitmap_parselist{ const int flags; }; -static const unsigned long exp[] = {1, 2, 0x0000ffff, 0xffff0000, 0x55555555, - 0xaaaaaaaa, 0x11111111, 0x22222222, 0xffffffff, - 0xfffffffe, 0x3333333311111111, 0xffffffff77777777}; -static const unsigned long exp2[] = {0x3333333311111111, 0xffffffff77777777}; +static const unsigned long exp[] __initconst = { + BITMAP_FROM_U64(1), + BITMAP_FROM_U64(2), + BITMAP_FROM_U64(0x0000ffff), + BITMAP_FROM_U64(0xffff0000), + BITMAP_FROM_U64(0x55555555), + BITMAP_FROM_U64(0xaaaaaaaa), + BITMAP_FROM_U64(0x11111111), + BITMAP_FROM_U64(0x22222222), + BITMAP_FROM_U64(0xffffffff), + BITMAP_FROM_U64(0xfffffffe), + BITMAP_FROM_U64(0x3333333311111111), + BITMAP_FROM_U64(0xffffffff77777777) +}; + +static const unsigned long exp2[] __initconst = { + BITMAP_FROM_U64(0x3333333311111111), + BITMAP_FROM_U64(0xffffffff77777777) +}; static const struct test_bitmap_parselist parselist_tests[] __initconst = { +#define step (sizeof(u64) / sizeof(unsigned long)) + {0, "0", &exp[0], 8, 0}, - {0, "1", &exp[1], 8, 0}, - {0, "0-15", &exp[2], 32, 0}, - {0, "16-31", &exp[3], 32, 0}, - {0, "0-31:1/2", &exp[4], 32, 0}, - {0, "1-31:1/2", &exp[5], 32, 0}, - {0, "0-31:1/4", &exp[6], 32, 0}, - {0, "1-31:1/4", &exp[7], 32, 0}, - {0, "0-31:4/4", &exp[8], 32, 0}, - {0, "1-31:4/4", &exp[9], 32, 0}, - {0, "0-31:1/4,32-63:2/4", &exp[10], 64, 0}, - {0, "0-31:3/4,32-63:4/4", &exp[11], 64, 0}, + {0, "1", &exp[1 * step], 8, 0}, + {0, "0-15", &exp[2 * step], 32, 0}, + {0, "16-31", &exp[3 * step], 32, 0}, + {0, "0-31:1/2", &exp[4 * step], 32, 0}, + {0, "1-31:1/2", &exp[5 * step], 32, 0}, + {0, "0-31:1/4", &exp[6 * step], 32, 0}, + {0, "1-31:1/4", &exp[7 * step], 32, 0}, + {0, "0-31:4/4", &exp[8 * step], 32, 0}, + {0, "1-31:4/4", &exp[9 * step], 32, 0}, + {0, "0-31:1/4,32-63:2/4", &exp[10 * step], 64, 0}, + {0, "0-31:3/4,32-63:4/4", &exp[11 * step], 64, 0}, {0, "0-31:1/4,32-63:2/4,64-95:3/4,96-127:4/4", exp2, 128, 0}, |