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bitfield.h: Fix "type of reg too small for mask" test
[ Upstream commit bff8c3848e
]
The test: 'mask > (typeof(_reg))~0ull' only works correctly when both
sides are unsigned, consider:
- 0xff000000 vs (int)~0ull
- 0x000000ff vs (int)~0ull
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101324.950210584@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
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1 changed files with 18 additions and 1 deletions
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@ -41,6 +41,22 @@
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#define __bf_shf(x) (__builtin_ffsll(x) - 1)
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#define __scalar_type_to_unsigned_cases(type) \
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unsigned type: (unsigned type)0, \
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signed type: (unsigned type)0
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#define __unsigned_scalar_typeof(x) typeof( \
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_Generic((x), \
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char: (unsigned char)0, \
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__scalar_type_to_unsigned_cases(char), \
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__scalar_type_to_unsigned_cases(short), \
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__scalar_type_to_unsigned_cases(int), \
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__scalar_type_to_unsigned_cases(long), \
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__scalar_type_to_unsigned_cases(long long), \
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default: (x)))
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#define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
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#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
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({ \
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BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \
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@ -49,7 +65,8 @@
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BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \
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~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
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_pfx "value too large for the field"); \
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BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \
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BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
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__bf_cast_unsigned(_reg, ~0ull), \
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_pfx "type of reg too small for mask"); \
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__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
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(1ULL << __bf_shf(_mask))); \
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