treewide: fix typo 'unsigned __init128' -> 'unsigned __int128'

"int" was misspelled as "init" the code comments in the bits.h and
const.h files. Fix the typo.

CC: Andy Shevchenko <andriy.shevchenko

treewide: fix typo 'unsigned __init128' -> 'unsigned __int128'

"int" was misspelled as "init" the code comments in the bits.h and
const.h files. Fix the typo.

CC: Andy Shevchenko <[email protected]>
Signed-off-by: Vincent Mailhol <[email protected]>
Signed-off-by: Yury Norov <[email protected]>

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linux/bits.h: simplify GENMASK_INPUT_CHECK()

In GENMASK_INPUT_CHECK(),

__builtin_choose_expr(__is_constexpr((l) > (h)), (l) > (h), 0)

is the exact expansion of:

const_true((l) > (h))

Apply c

linux/bits.h: simplify GENMASK_INPUT_CHECK()

In GENMASK_INPUT_CHECK(),

__builtin_choose_expr(__is_constexpr((l) > (h)), (l) > (h), 0)

is the exact expansion of:

const_true((l) > (h))

Apply const_true() to simplify GENMASK_INPUT_CHECK().

CC: Linus Torvalds <[email protected]>
CC: Rasmus Villemoes <[email protected]>
CC: Luc Van Oostenryck <[email protected]>
Reviewed-by: Yury Norov <[email protected]>,
Signed-off-by: Vincent Mailhol <[email protected]>
Signed-off-by: Yury Norov <[email protected]>

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uapi: Define GENMASK_U128

This adds GENMASK_U128() and __GENMASK_U128() macros using __BITS_PER_U128
and __int128 data types. These macros will be used in providing support for
generating 128 bit ma

uapi: Define GENMASK_U128

This adds GENMASK_U128() and __GENMASK_U128() macros using __BITS_PER_U128
and __int128 data types. These macros will be used in providing support for
generating 128 bit masks.

The macros wouldn't work in all assembler flavors for reasons described
in the comments on top of declarations. Enforce it for more by adding
!__ASSEMBLY__ guard.

Cc: Yury Norov <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Arnd Bergmann <[email protected]>>
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Arnd Bergmann <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Signed-off-by: Yury Norov <[email protected]>

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uapi: introduce uapi-friendly macros for GENMASK

Move __GENMASK and __GENMASK_ULL from include/ to include/uapi/ so that they can
be used to define masks in userspace API headers. Compared to what

uapi: introduce uapi-friendly macros for GENMASK

Move __GENMASK and __GENMASK_ULL from include/ to include/uapi/ so that they can
be used to define masks in userspace API headers. Compared to what is already
in include/linux/bits.h, the definitions need to use the uglified versions of
UL(), ULL(), BITS_PER_LONG and BITS_PER_LONG_LONG (which did not even exist),
but otherwise expand to the same content.

Signed-off-by: Paolo Bonzini <[email protected]>

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vdso/bits.h: Add BIT_ULL() for the sake of consistency

The minimization done in 3945ff37d2f4 ("linux/bits.h: Extract common header
for vDSO") was required to isolate the VDSO build from the larger k

vdso/bits.h: Add BIT_ULL() for the sake of consistency

The minimization done in 3945ff37d2f4 ("linux/bits.h: Extract common header
for vDSO") was required to isolate the VDSO build from the larger kernel
header impact.

The split added some inconsistency since BIT() and BIT_ULL() are now
defined in the different files which confuses unprepared reader.

Move BIT_ULL() to vdso/bits.h. No functional change.

Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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linux/bits.h: fix compilation error with GENMASK

GENMASK() has an input check which uses __builtin_choose_expr() to
enable a compile time sanity check of its inputs if they are known at
compile time

linux/bits.h: fix compilation error with GENMASK

GENMASK() has an input check which uses __builtin_choose_expr() to
enable a compile time sanity check of its inputs if they are known at
compile time.

However, it turns out that __builtin_constant_p() does not always return
a compile time constant [0]. It was thought this problem was fixed with
gcc 4.9 [1], but apparently this is not the case [2].

Switch to use __is_constexpr() instead which always returns a compile time
constant, regardless of its inputs.

Link: https://lore.kernel.org/lkml/[email protected] [0]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449 [1]
Link: https://lore.kernel.org/lkml/[email protected] [2]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Rikard Falkeborn <[email protected]>
Reported-by: Tetsuo Handa <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Yury Norov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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Raise gcc version requirement to 4.9

I realize that we fairly recently raised it to 4.8, but the fact is, 4.9
is a much better minimum version to target.

We have a number of workarounds for actual

Raise gcc version requirement to 4.9

I realize that we fairly recently raised it to 4.8, but the fact is, 4.9
is a much better minimum version to target.

We have a number of workarounds for actual bugs in pre-4.9 gcc versions
(including things like internal compiler errors on ARM), but we also
have some syntactic workarounds for lacking features.

In particular, raising the minimum to 4.9 means that we can now just
assume _Generic() exists, which is likely the much better replacement
for a lot of very convoluted built-time magic with conditionals on
sizeof and/or __builtin_choose_expr() with same_type() etc.

Using _Generic also means that you will need to have a very recent
version of 'sparse', but thats easy to build yourself, and much less of
a hassle than some old gcc version can be.

The latest (in a long string) of reasons for minimum compiler version
upgrades was commit 5435f73d5c4a ("efi/x86: Fix build with gcc 4").

Ard points out that RHEL 7 uses gcc-4.8, but the people who stay back on
old RHEL versions persumably also don't build their own kernels anyway.
And maybe they should cross-built or just have a little side affair with
a newer compiler?

Acked-by: Ard Biesheuvel <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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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. M

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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Masahiro Yamada <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Haren Myneni <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: lkml <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

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linux/bits.h: Extract common header for vDSO

The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this poss

linux/bits.h: Extract common header for vDSO

The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split bits.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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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, w

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/[email protected]
Signed-off-by: Masahiro Yamada <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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locking/atomics, asm-generic: Move some macros from <linux/bitops.h> to a new <linux/bits.h> file

In preparation for implementing the asm-generic atomic bitops in terms
of atomic_long_*(), we need t

locking/atomics, asm-generic: Move some macros from <linux/bitops.h> to a new <linux/bits.h> file

In preparation for implementing the asm-generic atomic bitops in terms
of atomic_long_*(), we need to prevent <asm/atomic.h> implementations from
pulling in <linux/bitops.h>. A common reason for this include is for the
BITS_PER_BYTE definition, so move this and some other BIT() and masking
macros into a new header file, <linux/bits.h>.

Signed-off-by: Will Deacon <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/lkml/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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