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arch: remove GENERIC_FIND_FIRST_BIT entirely 

In 5.12 cycle we enabled GENERIC_FIND_FIRST_BIT config option for ARM64
and MIPS. It increased performance and shrunk .text size; and so far
I didn't receive any negative feedback on the change.

https://lore.kernel.org/linux-arch/20210225135700.1381396-1-yury.norov@gmail.com/

Now I think it's a good time to switch all architectures to use
find_{first,last}_bit() unconditionally, and so remove corresponding
config option.

The patch does't introduce functioal changes for arc, arm, arm64, mips,
m68k, s390 and x86, for other architectures I expect improvement both in
performance and .text size.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Alexander Lobakin <alobakin@pm.me> (mips)
Reviewed-by: Alexander Lobakin <alobakin@pm.me> (mips)
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
This commit is contained in:
Yury Norov 2021-08-14 14:17:00 -07:00
parent 47d8c15615
commit c126a53c27
8 changed files with 0 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arc/Kconfig
View File

@ -20,7 +20,6 @@ config ARC
select COMMON_CLK
select DMA_DIRECT_REMAP
select GENERIC_ATOMIC64 if !ISA_ARCV2 || !(ARC_HAS_LL64 && ARC_HAS_LLSC)
select GENERIC_FIND_FIRST_BIT
# for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP
select GENERIC_IRQ_SHOW
select GENERIC_PCI_IOMAP

1
arch/arm64/Kconfig
View File

@ -120,7 +120,6 @@ config ARM64
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_VULNERABILITIES
select GENERIC_EARLY_IOREMAP
select GENERIC_FIND_FIRST_BIT
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_IPI
select GENERIC_IRQ_PROBE

1
arch/mips/Kconfig
View File

@ -32,7 +32,6 @@ config MIPS
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_CMOS_UPDATE
select GENERIC_CPU_AUTOPROBE
select GENERIC_FIND_FIRST_BIT
select GENERIC_GETTIMEOFDAY
select GENERIC_IOMAP
select GENERIC_IRQ_PROBE

1
arch/s390/Kconfig
View File

@ -127,7 +127,6 @@ config S390
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_VULNERABILITIES
select GENERIC_ENTRY
select GENERIC_FIND_FIRST_BIT
select GENERIC_GETTIMEOFDAY
select GENERIC_PTDUMP
select GENERIC_SMP_IDLE_THREAD

1
arch/x86/Kconfig
View File

@ -136,7 +136,6 @@ config X86
select GENERIC_CPU_VULNERABILITIES
select GENERIC_EARLY_IOREMAP
select GENERIC_ENTRY
select GENERIC_FIND_FIRST_BIT
select GENERIC_IOMAP
select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC

1
arch/x86/um/Kconfig
View File

@ -8,7 +8,6 @@ endmenu
config UML_X86
def_bool y
select GENERIC_FIND_FIRST_BIT
config 64BIT
bool "64-bit kernel" if "$(SUBARCH)" = "x86"

13
include/linux/find.h
View File

@ -101,8 +101,6 @@ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
}
#endif
#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
#ifndef find_first_bit
/**
* find_first_bit - find the first set bit in a memory region
@ -147,17 +145,6 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
}
#endif
#else /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifndef find_first_bit
#define find_first_bit(addr, size) find_next_bit((addr), (size), 0)
#endif
#ifndef find_first_zero_bit
#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0)
#endif
#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifndef find_last_bit
/**
* find_last_bit - find the last set bit in a memory region

3
lib/Kconfig
View File

@ -65,9 +65,6 @@ config GENERIC_STRNLEN_USER
config GENERIC_NET_UTILS
bool
config GENERIC_FIND_FIRST_BIT
bool
source "lib/math/Kconfig"
config NO_GENERIC_PCI_IOPORT_MAP