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Message-Id: <20210510233421.18684-1-yury.norov@gmail.com>
Date: Mon, 10 May 2021 16:34:21 -0700
From: Yury Norov <yury.norov@...il.com>
To: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Cc: Yury Norov <yury.norov@...il.com>,
Alexander Lobakin <alobakin@...me>,
Alexey Klimov <aklimov@...hat.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
Catalin Marinas <catalin.marinas@....com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Dan Williams <dan.j.williams@...el.com>,
"H. Peter Anvin" <hpa@...or.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Ingo Molnar <mingo@...hat.com>,
Jacob Keller <jacob.e.keller@...el.com>,
Jarkko Sakkinen <jarkko@...nel.org>,
Jeff Dike <jdike@...toit.com>,
Kees Cook <keescook@...omium.org>,
Mark Brown <broonie@...nel.org>,
Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
Nick Terrell <terrelln@...com>,
Palmer Dabbelt <palmerdabbelt@...gle.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Richard Weinberger <richard@....at>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Thomas Gleixner <tglx@...utronix.de>,
Vasily Gorbik <gor@...ux.ibm.com>,
Vijayanand Jitta <vjitta@...eaurora.org>,
Vineet Gupta <vgupta@...opsys.com>,
Will Deacon <will@...nel.org>, Yogesh Lal <ylal@...eaurora.org>
Subject: [PATCH] all: remove GENERIC_FIND_FIRST_BIT
In the 5.12 cycle we enabled the 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/
I think it's time to make all architectures use find_{first,last}_bit()
unconditionally and remove the corresponding config option.
This patch doesn't introduce functional changes for arc, arm64, mips,
s390 and x86 because they already enable GENERIC_FIND_FIRST_BIT. There
will be no changes for arm because it implements find_{first,last}_bit
in arch code. For other architectures I expect improvement both in
performance and .text size.
It would be great if people with an access to real hardware would share
the output of bloat-o-meter and lib/find_bit_benchmark.
Signed-off-by: Yury Norov <yury.norov@...il.com>
---
arch/arc/Kconfig | 1 -
arch/arm64/Kconfig | 1 -
arch/mips/Kconfig | 1 -
arch/s390/Kconfig | 1 -
arch/x86/Kconfig | 1 -
arch/x86/um/Kconfig | 1 -
include/asm-generic/bitops/find.h | 12 ------------
lib/Kconfig | 3 ---
8 files changed, 21 deletions(-)
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index bc8d6aecfbbd..9c991ba50db3 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -19,7 +19,6 @@ 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
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e09a9591af45..9d5b36f7d981 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -108,7 +108,6 @@ 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
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b72458215d20..3ddae7918386 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -27,7 +27,6 @@ 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
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c1ff874e6c2e..3a10ceb8a097 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -125,7 +125,6 @@ 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
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b83364a15d34..6a7d8305365e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -123,7 +123,6 @@ 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
diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index 95d26a69088b..40d6a06e41c8 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -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"
diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 0d132ee2a291..8a7b70c79e15 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -95,8 +95,6 @@ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
}
#endif
-#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
-
/**
* find_first_bit - find the first set bit in a memory region
* @addr: The address to start the search at
@@ -136,16 +134,6 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
return _find_first_zero_bit(addr, size);
}
-#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
/**
diff --git a/lib/Kconfig b/lib/Kconfig
index a38cc61256f1..8346b3181214 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -59,9 +59,6 @@ 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
--
2.25.1
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