2018-06-19 19:53:08 +07:00
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_BITS_H
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#define __LINUX_BITS_H
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linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
BIT(), GENMASK(), etc. are useful to define register bits of hardware.
However, low-level code is often written in assembly, where they are
not available due to the hard-coded 1UL, 0UL.
In fact, in-kernel headers such as arch/arm64/include/asm/sysreg.h
use _BITUL() instead of BIT() so that the register bit macros are
available in assembly.
Using macros in include/uapi/linux/const.h have two reasons:
[1] For use in uapi headers
We should use underscore-prefixed variants for user-space.
[2] For use in assembly code
Since _BITUL() uses UL(1) instead of 1UL, it can be used as an
alternative of BIT().
For [2], it is pretty easy to change BIT() etc. for use in assembly.
This allows to replace _BUTUL() in kernel-space headers with BIT().
Link: http://lkml.kernel.org/r/20190609153941.17249-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-17 06:26:57 +07:00
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#include <linux/const.h>
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2020-03-20 21:53:27 +07:00
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#include <vdso/bits.h>
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2018-06-19 19:53:08 +07:00
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#include <asm/bitsperlong.h>
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linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
BIT(), GENMASK(), etc. are useful to define register bits of hardware.
However, low-level code is often written in assembly, where they are
not available due to the hard-coded 1UL, 0UL.
In fact, in-kernel headers such as arch/arm64/include/asm/sysreg.h
use _BITUL() instead of BIT() so that the register bit macros are
available in assembly.
Using macros in include/uapi/linux/const.h have two reasons:
[1] For use in uapi headers
We should use underscore-prefixed variants for user-space.
[2] For use in assembly code
Since _BITUL() uses UL(1) instead of 1UL, it can be used as an
alternative of BIT().
For [2], it is pretty easy to change BIT() etc. for use in assembly.
This allows to replace _BUTUL() in kernel-space headers with BIT().
Link: http://lkml.kernel.org/r/20190609153941.17249-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-17 06:26:57 +07:00
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#define BIT_ULL(nr) (ULL(1) << (nr))
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#define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG))
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2018-06-19 19:53:08 +07:00
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#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
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linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
BIT(), GENMASK(), etc. are useful to define register bits of hardware.
However, low-level code is often written in assembly, where they are
not available due to the hard-coded 1UL, 0UL.
In fact, in-kernel headers such as arch/arm64/include/asm/sysreg.h
use _BITUL() instead of BIT() so that the register bit macros are
available in assembly.
Using macros in include/uapi/linux/const.h have two reasons:
[1] For use in uapi headers
We should use underscore-prefixed variants for user-space.
[2] For use in assembly code
Since _BITUL() uses UL(1) instead of 1UL, it can be used as an
alternative of BIT().
For [2], it is pretty easy to change BIT() etc. for use in assembly.
This allows to replace _BUTUL() in kernel-space headers with BIT().
Link: http://lkml.kernel.org/r/20190609153941.17249-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-17 06:26:57 +07:00
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#define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG))
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2018-06-19 19:53:08 +07:00
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#define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG)
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#define BITS_PER_BYTE 8
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/*
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* Create a contiguous bitmask starting at bit position @l and ending at
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* position @h. For example
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* GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
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*/
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linux/bits.h: add compile time sanity check of GENMASK inputs
GENMASK() and GENMASK_ULL() are supposed to be called with the high bit as
the first argument and the low bit as the second argument. Mixing them
will return a mask with zero bits set.
Recent commits show getting this wrong is not uncommon, see e.g. commit
aa4c0c9091b0 ("net: stmmac: Fix misuses of GENMASK macro") and commit
9bdd7bb3a844 ("clocksource/drivers/npcm: Fix misuse of GENMASK macro").
To prevent such mistakes from appearing again, add compile time sanity
checking to the arguments of GENMASK() and GENMASK_ULL(). If both
arguments are known at compile time, and the low bit is higher than the
high bit, break the build to detect the mistake immediately.
Since GENMASK() is used in declarations, BUILD_BUG_ON_ZERO() must be used
instead of BUILD_BUG_ON().
__builtin_constant_p does not evaluate is argument, it only checks if it
is a constant or not at compile time, and __builtin_choose_expr does not
evaluate the expression that is not chosen. Therefore, GENMASK(x++, 0)
does only evaluate x++ once.
Commit 95b980d62d52 ("linux/bits.h: make BIT(), GENMASK(), and friends
available in assembly") made the macros in linux/bits.h available in
assembly. Since BUILD_BUG_OR_ZERO() is not asm compatible, disable the
checks if the file is included in an asm file.
Due to bugs in GCC versions before 4.9 [0], disable the check if building
with a too old GCC compiler.
[0]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Haren Myneni <haren@us.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200308193954.2372399-1-rikard.falkeborn@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:10:38 +07:00
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#if !defined(__ASSEMBLY__) && \
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(!defined(CONFIG_CC_IS_GCC) || CONFIG_GCC_VERSION >= 49000)
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#include <linux/build_bug.h>
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#define GENMASK_INPUT_CHECK(h, l) \
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(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
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__builtin_constant_p((l) > (h)), (l) > (h), 0)))
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#else
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/*
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* BUILD_BUG_ON_ZERO is not available in h files included from asm files,
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* disable the input check if that is the case.
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*/
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#define GENMASK_INPUT_CHECK(h, l) 0
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#endif
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#define __GENMASK(h, l) \
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linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
BIT(), GENMASK(), etc. are useful to define register bits of hardware.
However, low-level code is often written in assembly, where they are
not available due to the hard-coded 1UL, 0UL.
In fact, in-kernel headers such as arch/arm64/include/asm/sysreg.h
use _BITUL() instead of BIT() so that the register bit macros are
available in assembly.
Using macros in include/uapi/linux/const.h have two reasons:
[1] For use in uapi headers
We should use underscore-prefixed variants for user-space.
[2] For use in assembly code
Since _BITUL() uses UL(1) instead of 1UL, it can be used as an
alternative of BIT().
For [2], it is pretty easy to change BIT() etc. for use in assembly.
This allows to replace _BUTUL() in kernel-space headers with BIT().
Link: http://lkml.kernel.org/r/20190609153941.17249-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-17 06:26:57 +07:00
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(((~UL(0)) - (UL(1) << (l)) + 1) & \
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(~UL(0) >> (BITS_PER_LONG - 1 - (h))))
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linux/bits.h: add compile time sanity check of GENMASK inputs
GENMASK() and GENMASK_ULL() are supposed to be called with the high bit as
the first argument and the low bit as the second argument. Mixing them
will return a mask with zero bits set.
Recent commits show getting this wrong is not uncommon, see e.g. commit
aa4c0c9091b0 ("net: stmmac: Fix misuses of GENMASK macro") and commit
9bdd7bb3a844 ("clocksource/drivers/npcm: Fix misuse of GENMASK macro").
To prevent such mistakes from appearing again, add compile time sanity
checking to the arguments of GENMASK() and GENMASK_ULL(). If both
arguments are known at compile time, and the low bit is higher than the
high bit, break the build to detect the mistake immediately.
Since GENMASK() is used in declarations, BUILD_BUG_ON_ZERO() must be used
instead of BUILD_BUG_ON().
__builtin_constant_p does not evaluate is argument, it only checks if it
is a constant or not at compile time, and __builtin_choose_expr does not
evaluate the expression that is not chosen. Therefore, GENMASK(x++, 0)
does only evaluate x++ once.
Commit 95b980d62d52 ("linux/bits.h: make BIT(), GENMASK(), and friends
available in assembly") made the macros in linux/bits.h available in
assembly. Since BUILD_BUG_OR_ZERO() is not asm compatible, disable the
checks if the file is included in an asm file.
Due to bugs in GCC versions before 4.9 [0], disable the check if building
with a too old GCC compiler.
[0]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Haren Myneni <haren@us.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200308193954.2372399-1-rikard.falkeborn@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:10:38 +07:00
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#define GENMASK(h, l) \
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(GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
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2018-06-19 19:53:08 +07:00
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linux/bits.h: add compile time sanity check of GENMASK inputs
GENMASK() and GENMASK_ULL() are supposed to be called with the high bit as
the first argument and the low bit as the second argument. Mixing them
will return a mask with zero bits set.
Recent commits show getting this wrong is not uncommon, see e.g. commit
aa4c0c9091b0 ("net: stmmac: Fix misuses of GENMASK macro") and commit
9bdd7bb3a844 ("clocksource/drivers/npcm: Fix misuse of GENMASK macro").
To prevent such mistakes from appearing again, add compile time sanity
checking to the arguments of GENMASK() and GENMASK_ULL(). If both
arguments are known at compile time, and the low bit is higher than the
high bit, break the build to detect the mistake immediately.
Since GENMASK() is used in declarations, BUILD_BUG_ON_ZERO() must be used
instead of BUILD_BUG_ON().
__builtin_constant_p does not evaluate is argument, it only checks if it
is a constant or not at compile time, and __builtin_choose_expr does not
evaluate the expression that is not chosen. Therefore, GENMASK(x++, 0)
does only evaluate x++ once.
Commit 95b980d62d52 ("linux/bits.h: make BIT(), GENMASK(), and friends
available in assembly") made the macros in linux/bits.h available in
assembly. Since BUILD_BUG_OR_ZERO() is not asm compatible, disable the
checks if the file is included in an asm file.
Due to bugs in GCC versions before 4.9 [0], disable the check if building
with a too old GCC compiler.
[0]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Haren Myneni <haren@us.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200308193954.2372399-1-rikard.falkeborn@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:10:38 +07:00
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#define __GENMASK_ULL(h, l) \
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linux/bits.h: make BIT(), GENMASK(), and friends available in assembly
BIT(), GENMASK(), etc. are useful to define register bits of hardware.
However, low-level code is often written in assembly, where they are
not available due to the hard-coded 1UL, 0UL.
In fact, in-kernel headers such as arch/arm64/include/asm/sysreg.h
use _BITUL() instead of BIT() so that the register bit macros are
available in assembly.
Using macros in include/uapi/linux/const.h have two reasons:
[1] For use in uapi headers
We should use underscore-prefixed variants for user-space.
[2] For use in assembly code
Since _BITUL() uses UL(1) instead of 1UL, it can be used as an
alternative of BIT().
For [2], it is pretty easy to change BIT() etc. for use in assembly.
This allows to replace _BUTUL() in kernel-space headers with BIT().
Link: http://lkml.kernel.org/r/20190609153941.17249-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-17 06:26:57 +07:00
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(((~ULL(0)) - (ULL(1) << (l)) + 1) & \
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(~ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
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linux/bits.h: add compile time sanity check of GENMASK inputs
GENMASK() and GENMASK_ULL() are supposed to be called with the high bit as
the first argument and the low bit as the second argument. Mixing them
will return a mask with zero bits set.
Recent commits show getting this wrong is not uncommon, see e.g. commit
aa4c0c9091b0 ("net: stmmac: Fix misuses of GENMASK macro") and commit
9bdd7bb3a844 ("clocksource/drivers/npcm: Fix misuse of GENMASK macro").
To prevent such mistakes from appearing again, add compile time sanity
checking to the arguments of GENMASK() and GENMASK_ULL(). If both
arguments are known at compile time, and the low bit is higher than the
high bit, break the build to detect the mistake immediately.
Since GENMASK() is used in declarations, BUILD_BUG_ON_ZERO() must be used
instead of BUILD_BUG_ON().
__builtin_constant_p does not evaluate is argument, it only checks if it
is a constant or not at compile time, and __builtin_choose_expr does not
evaluate the expression that is not chosen. Therefore, GENMASK(x++, 0)
does only evaluate x++ once.
Commit 95b980d62d52 ("linux/bits.h: make BIT(), GENMASK(), and friends
available in assembly") made the macros in linux/bits.h available in
assembly. Since BUILD_BUG_OR_ZERO() is not asm compatible, disable the
checks if the file is included in an asm file.
Due to bugs in GCC versions before 4.9 [0], disable the check if building
with a too old GCC compiler.
[0]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Haren Myneni <haren@us.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200308193954.2372399-1-rikard.falkeborn@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:10:38 +07:00
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#define GENMASK_ULL(h, l) \
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(GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
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2018-06-19 19:53:08 +07:00
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#endif /* __LINUX_BITS_H */
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