kernel/linux.git/arch/mips/include/asm/bitops.h, branch v6.19.11

mips: Add __attribute_const__ to ffs()-family implementations

2025-09-08T21:58:51+00:00

While tracking down a problem where constant expressions used by BUILD_BUG_ON() suddenly stopped working[1], we found that an added static initializer was convincing the compiler that it couldn't track the state of the prior statically initialized value. Tracing this down found that ffs() was used in the initializer macro, but since it wasn't marked with __attribute__const__, the compiler had to assume the function might change variable states as a side-effect (which is not true for ffs(), which provides deterministic math results). Add missing __attribute_const__ annotations to MIPS's implementations of ffs(), __ffs(), fls(), and __fls() functions. These are pure mathematical functions that always return the same result for the same input with no side effects, making them eligible for compiler optimization. Build tested ARCH=mips defconfig with GCC mipsel-linux-gnu 14.2.0. Link: https://github.com/KSPP/linux/issues/364 [1] Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250804164417.1612371-12-kees@kernel.org Signed-off-by: Kees Cook

mm: delete checks for xor_unlock_is_negative_byte()

2023-10-18T21:34:17+00:00

Architectures which don't define their own use the one in asm-generic/bitops/lock.h. Get rid of all the ifdefs around "maybe we don't have it". Link: https://lkml.kernel.org/r/20231004165317.1061855-15-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Geert Uytterhoeven Cc: Albert Ou Cc: Alexander Gordeev Cc: Andreas Dilger Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Heiko Carstens Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Sven Schnelle Cc: "Theodore Ts'o" Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Signed-off-by: Andrew Morton

mips: implement xor_unlock_is_negative_byte

2023-10-18T21:34:17+00:00

Inspired by the mips test_and_change_bit(), this will surely be more efficient than the generic one defined in filemap.c Link: https://lkml.kernel.org/r/20231004165317.1061855-11-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Albert Ou Cc: Alexander Gordeev Cc: Andreas Dilger Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Geert Uytterhoeven Cc: Heiko Carstens Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Sven Schnelle Cc: "Theodore Ts'o" Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Signed-off-by: Andrew Morton

Merge tag 'bitmap-5.17-rc1' of git://github.com/norov/linux

2022-01-23T04:20:44+00:00

Pull bitmap updates from Yury Norov: - introduce for_each_set_bitrange() - use find_first_*_bit() instead of find_next_*_bit() where possible - unify for_each_bit() macros * tag 'bitmap-5.17-rc1' of git://github.com/norov/linux: vsprintf: rework bitmap_list_string lib: bitmap: add performance test for bitmap_print_to_pagebuf bitmap: unify find_bit operations mm/percpu: micro-optimize pcpu_is_populated() Replace for_each_*_bit_from() with for_each_*_bit() where appropriate find: micro-optimize for_each_{set,clear}_bit() include/linux: move for_each_bit() macros from bitops.h to find.h cpumask: replace cpumask_next_* with cpumask_first_* where appropriate tools: sync tools/bitmap with mother linux all: replace find_next{,_zero}_bit with find_first{,_zero}_bit where appropriate cpumask: use find_first_and_bit() lib: add find_first_and_bit() arch: remove GENERIC_FIND_FIRST_BIT entirely include: move find.h from asm_generic to linux bitops: move find_bit_*_le functions from le.h to find.h bitops: protect find_first_{,zero}_bit properly

include: move find.h from asm_generic to linux

2022-01-15T16:47:31+00:00

find_bit API and bitmap API are closely related, but inclusion paths are different - include/asm-generic and include/linux, correspondingly. In the past it made a lot of troubles due to circular dependencies and/or undefined symbols. Fix this by moving find.h under include/linux. Signed-off-by: Yury Norov Tested-by: Wolfram Sang Acked-by: Geert Uytterhoeven

MIPS: retire "asm/llsc.h"

2022-01-05T10:16:35+00:00

all that "asm/llsc.h" does is just to help inline asm, which can be stringifyed from "asm/asm.h" +. Since "asm/asm.h" has all we need, retire "asm/llsc.h" +. remove unused header file Inspired-by: Maciej W. Rozycki Signed-off-by: Huang Pei Signed-off-by: Thomas Bogendoerfer

MIPS: bitops: fix -Wshadow in asm/bitops.h

2021-01-15T14:28:56+00:00

Solves the following repetitive warning when building with -Wshadow: In file included from ./include/linux/bitops.h:32, from ./include/linux/kernel.h:11, from ./include/linux/skbuff.h:13, from ./include/linux/if_ether.h:19, from ./include/linux/etherdevice.h:20: ./arch/mips/include/asm/bitops.h: In function ‘test_and_set_bit_lock’: ./arch/mips/include/asm/bitops.h:46:16: warning: declaration of ‘orig’ shadows a previous local [-Wshadow] 46 | unsigned long orig, temp; \ | ^~~~ ./arch/mips/include/asm/bitops.h:190:10: note: in expansion of macro ‘__test_bit_op’ 190 | orig = __test_bit_op(*m, "%0", | ^~~~~~~~~~~~~ ./arch/mips/include/asm/bitops.h:185:21: note: shadowed declaration is here 185 | unsigned long res, orig; | ^~~~ ./arch/mips/include/asm/bitops.h: In function ‘test_and_clear_bit’: ./arch/mips/include/asm/bitops.h:46:16: warning: declaration of ‘orig’ shadows a previous local [-Wshadow] 46 | unsigned long orig, temp; \ | ^~~~ ./arch/mips/include/asm/bitops.h:236:9: note: in expansion of macro ‘__test_bit_op’ 236 | res = __test_bit_op(*m, "%1", | ^~~~~~~~~~~~~ ./arch/mips/include/asm/bitops.h:229:21: note: shadowed declaration is here 229 | unsigned long res, orig; | ^~~~ ./arch/mips/include/asm/bitops.h:46:16: warning: declaration of ‘orig’ shadows a previous local [-Wshadow] 46 | unsigned long orig, temp; \ | ^~~~ ./arch/mips/include/asm/bitops.h:241:10: note: in expansion of macro ‘__test_bit_op’ 241 | orig = __test_bit_op(*m, "%0", | ^~~~~~~~~~~~~ ./arch/mips/include/asm/bitops.h:229:21: note: shadowed declaration is here 229 | unsigned long res, orig; | ^~~~ ./arch/mips/include/asm/bitops.h: In function ‘test_and_change_bit’: ./arch/mips/include/asm/bitops.h:46:16: warning: declaration of ‘orig’ shadows a previous local [-Wshadow] 46 | unsigned long orig, temp; \ | ^~~~ ./arch/mips/include/asm/bitops.h:273:10: note: in expansion of macro ‘__test_bit_op’ 273 | orig = __test_bit_op(*m, "%0", | ^~~~~~~~~~~~~ ./arch/mips/include/asm/bitops.h:266:21: note: shadowed declaration is here 266 | unsigned long res, orig; | ^~~~ Signed-off-by: Alexander Lobakin Signed-off-by: Thomas Bogendoerfer

MIPS: bitops: Fix reference to ffz location

2021-01-09T11:04:03+00:00

Unlike most other architectures, MIPS defines ffz() below ffs(). Signed-off-by: Geert Uytterhoeven Signed-off-by: Thomas Bogendoerfer

MIPS: bitops: Use smp_mb__before_atomic in test_* ops

2019-10-07T16:42:58+00:00

Use smp_mb__before_atomic() rather than smp_mb__before_llsc() in test_and_set_bit(), test_and_clear_bit() & test_and_change_bit(). The _atomic() versions make semantic sense in these cases, and will allow a later patch to omit redundant barriers for Loongson3 systems that already include a barrier within __test_bit_op(). Signed-off-by: Paul Burton Cc: linux-mips@vger.kernel.org Cc: Huacai Chen Cc: Jiaxun Yang Cc: linux-kernel@vger.kernel.org

MIPS: bitops: Emit Loongson3 sync workarounds within asm

2019-10-07T16:42:57+00:00

Generate the sync instructions required to workaround Loongson3 LL/SC errata within inline asm blocks, which feels a little safer than doing it from C where strictly speaking the compiler would be well within its rights to insert a memory access between the separate asm statements we previously had, containing sync & ll instructions respectively. Signed-off-by: Paul Burton Cc: linux-mips@vger.kernel.org Cc: Huacai Chen Cc: Jiaxun Yang Cc: linux-kernel@vger.kernel.org