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62357a5888
The value of __BITS_PER_LONG from architecture-specific logic should
always match the generic one if that is available. It should also match
the actual C type 'long'.
Mismatches can happen for example when building the compat vDSO. Either
during the compilation, see commit 9a6d3ff10f ("arm64: uapi: Provide
correct __BITS_PER_LONG for the compat vDSO"), or when running sparse
when mismatched CHECKFLAGS are inherited from the kernel build.
Add some consistency checks which detect such issues early and clearly.
The kernel-internal BITS_PER_LONG is not checked as it is derived from
CONFIG_64BIT and therefore breaks for the compat vDSO. See the similar,
deactivated check above.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260302-vdso-compat-checkflags-v2-5-78e55baa58ba@linutronix.de
48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_GENERIC_BITS_PER_LONG
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#define __ASM_GENERIC_BITS_PER_LONG
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#include <uapi/asm-generic/bitsperlong.h>
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#ifdef CONFIG_64BIT
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#define BITS_PER_LONG 64
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#else
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#define BITS_PER_LONG 32
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#endif /* CONFIG_64BIT */
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/*
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* FIXME: The check currently breaks x86-64 build, so it's
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* temporarily disabled. Please fix x86-64 and reenable
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*/
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#if 0 && BITS_PER_LONG != __BITS_PER_LONG
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#error Inconsistent word size. Check asm/bitsperlong.h
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#endif
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#if __CHAR_BIT__ * __SIZEOF_LONG__ != __BITS_PER_LONG
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#error Inconsistent word size. Check asm/bitsperlong.h
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#endif
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#ifndef __ASSEMBLER__
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_Static_assert(sizeof(long) * 8 == __BITS_PER_LONG,
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"Inconsistent word size. Check asm/bitsperlong.h");
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#endif
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#ifndef BITS_PER_LONG_LONG
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#define BITS_PER_LONG_LONG 64
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#endif
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/*
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* small_const_nbits(n) is true precisely when it is known at compile-time
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* that BITMAP_SIZE(n) is 1, i.e. 1 <= n <= BITS_PER_LONG. This allows
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* various bit/bitmap APIs to provide a fast inline implementation. Bitmaps
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* of size 0 are very rare, and a compile-time-known-size 0 is most likely
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* a sign of error. They will be handled correctly by the bit/bitmap APIs,
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* but using the out-of-line functions, so that the inline implementations
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* can unconditionally dereference the pointer(s).
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*/
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#define small_const_nbits(nbits) \
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(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
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#endif /* __ASM_GENERIC_BITS_PER_LONG */
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