From: Yury Norov <yury.norov@xxxxxxxxx> Subject: tools: sync lib/find_bit implementation Add fast paths to find_*_bit() functions as per kernel implementation. Link: https://lkml.kernel.org/r/20210401003153.97325-12-yury.norov@xxxxxxxxx Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx> Acked-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Alexey Klimov <aklimov@xxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: David Sterba <dsterba@xxxxxxxx> Cc: Dennis Zhou <dennis@xxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: Jianpeng Ma <jianpeng.ma@xxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Rich Felker <dalias@xxxxxxxx> Cc: Stefano Brivio <sbrivio@xxxxxxxxxx> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> Cc: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/include/asm-generic/bitops/find.h | 58 ++++++++++++++++++++-- tools/lib/find_bit.c | 4 - 2 files changed, 57 insertions(+), 5 deletions(-) --- a/tools/include/asm-generic/bitops/find.h~tools-sync-lib-find_bit-implementation +++ a/tools/include/asm-generic/bitops/find.h @@ -5,6 +5,9 @@ extern unsigned long _find_next_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long nbits, unsigned long start, unsigned long invert, unsigned long le); +extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size); +extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size); +extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size); #ifndef find_next_bit /** @@ -20,6 +23,16 @@ static inline unsigned long find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { + if (small_const_nbits(size)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr, NULL, size, offset, 0UL, 0); } #endif @@ -40,6 +53,16 @@ unsigned long find_next_and_bit(const un const unsigned long *addr2, unsigned long size, unsigned long offset) { + if (small_const_nbits(size)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr1 & *addr2 & GENMASK(size - 1, offset); + return val ? __ffs(val) : size; + } + return _find_next_bit(addr1, addr2, size, offset, 0UL, 0); } #endif @@ -58,6 +81,16 @@ static inline unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { + if (small_const_nbits(size)) { + unsigned long val; + + if (unlikely(offset >= size)) + return size; + + val = *addr | ~GENMASK(size - 1, offset); + return val == ~0UL ? size : ffz(val); + } + return _find_next_bit(addr, NULL, size, offset, ~0UL, 0); } #endif @@ -72,8 +105,17 @@ unsigned long find_next_zero_bit(const u * Returns the bit number of the first set bit. * If no bits are set, returns @size. */ -extern unsigned long find_first_bit(const unsigned long *addr, - unsigned long size); +static inline +unsigned long find_first_bit(const unsigned long *addr, unsigned long size) +{ + if (small_const_nbits(size)) { + unsigned long val = *addr & GENMASK(size - 1, 0); + + return val ? __ffs(val) : size; + } + + return _find_first_bit(addr, size); +} #endif /* find_first_bit */ @@ -87,7 +129,17 @@ extern unsigned long find_first_bit(cons * Returns the bit number of the first cleared bit. * If no bits are zero, returns @size. */ -unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size); +static inline +unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) +{ + if (small_const_nbits(size)) { + unsigned long val = *addr | ~GENMASK(size - 1, 0); + + return val == ~0UL ? size : ffz(val); + } + + return _find_first_zero_bit(addr, size); +} #endif #endif /*_TOOLS_LINUX_ASM_GENERIC_BITOPS_FIND_H_ */ --- a/tools/lib/find_bit.c~tools-sync-lib-find_bit-implementation +++ a/tools/lib/find_bit.c @@ -83,7 +83,7 @@ unsigned long _find_next_bit(const unsig /* * Find the first set bit in a memory region. */ -unsigned long find_first_bit(const unsigned long *addr, unsigned long size) +unsigned long _find_first_bit(const unsigned long *addr, unsigned long size) { unsigned long idx; @@ -100,7 +100,7 @@ unsigned long find_first_bit(const unsig /* * Find the first cleared bit in a memory region. */ -unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) +unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size) { unsigned long idx; _
