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Now that kernel mode NEON no longer disables preemption, using FP/SIMD
in library code which is not obviously part of the crypto subsystem is
no longer problematic, as it will no longer incur unexpected latencies.
So accelerate the CRC-32 library code on arm64 to use a 4-way
interleave, using PMULL instructions to implement the folding.
On Apple M2, this results in a speedup of 2 - 2.8x when using input
sizes of 1k - 8k. For smaller sizes, the overhead of preserving and
restoring the FP/SIMD register file may not be worth it, so 1k is used
as a threshold for choosing this code path.
The coefficient tables were generated using code provided by Eric. [0]
[0] https://github.com/ebiggers/libdeflate/blob/master/scripts/gen_crc32_multipliers.c
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20241018075347.2821102-8-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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In preparation for a new user, reorganize the bit/byte ordering macros
that are used to parameterize the crc32 template code and instantiate
CRC-32, CRC-32c and 'big endian' CRC-32.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20241018075347.2821102-7-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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In preparation for adding another code path for performing CRC-32, move
the alternative patching for ARM64_HAS_CRC32 into C code. The logic for
deciding whether to use this new code path will be implemented in C too.
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20241018075347.2821102-6-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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It makes no sense to leave crc32_be using the generic code while we
only accelerate the little-endian ops.
Even though the big-endian form doesn't fit as smoothly into the arm64,
we can speed it up and avoid hitting the D cache.
Tested on Cortex-A53. Without acceleration:
crc32: CRC_LE_BITS = 64, CRC_BE BITS = 64
crc32: self tests passed, processed 225944 bytes in 192240 nsec
crc32c: CRC_LE_BITS = 64
crc32c: self tests passed, processed 112972 bytes in 21360 nsec
With acceleration:
crc32: CRC_LE_BITS = 64, CRC_BE BITS = 64
crc32: self tests passed, processed 225944 bytes in 53480 nsec
crc32c: CRC_LE_BITS = 64
crc32c: self tests passed, processed 112972 bytes in 21480 nsec
Signed-off-by: Kevin Bracey <kevin@bracey.fi>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Currently most of the assembly files that use architecture extensions
enable them using the .arch directive but crc32.S uses .cpu instead. Move
that over to .arch for consistency.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20200414182843.31664-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
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In an effort to clarify and simplify the annotation of assembly functions
in the kernel new macros have been introduced. These replace ENTRY and
ENDPROC and also add a new annotation for static functions which previously
had no ENTRY equivalent. Update the annotations in the library code to the
new macros.
Signed-off-by: Mark Brown <broonie@kernel.org>
[will: Use SYM_FUNC_START_WEAK_PI]
Signed-off-by: Will Deacon <will@kernel.org>
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Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Improve the performance of the crc32() asm routines by getting rid of
most of the branches and small sized loads on the common path.
Instead, use a branchless code path involving overlapping 16 byte
loads to process the first (length % 32) bytes, and process the
remainder using a loop that processes 32 bytes at a time.
Tested using the following test program:
#include <stdlib.h>
extern void crc32_le(unsigned short, char const*, int);
int main(void)
{
static const char buf[4096];
srand(20181126);
for (int i = 0; i < 100 * 1000 * 1000; i++)
crc32_le(0, buf, rand() % 1024);
return 0;
}
On Cortex-A53 and Cortex-A57, the performance regresses but only very
slightly. On Cortex-A72 however, the performance improves from
$ time ./crc32
real 0m10.149s
user 0m10.149s
sys 0m0.000s
to
$ time ./crc32
real 0m7.915s
user 0m7.915s
sys 0m0.000s
Cc: Rui Sun <sunrui26@huawei.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Unlike crc32c(), which is wired up to the crypto API internally so the
optimal driver is selected based on the platform's capabilities,
crc32_le() is implemented as a library function using a slice-by-8 table
based C implementation. Even though few of the call sites may be
bottlenecks, calling a time variant implementation with a non-negligible
D-cache footprint is a bit of a waste, given that ARMv8.1 and up mandates
support for the CRC32 instructions that were optional in ARMv8.0, but are
already widely available, even on the Cortex-A53 based Raspberry Pi.
So implement routines that use these instructions if available, and fall
back to the existing generic routines otherwise. The selection is based
on alternatives patching.
Note that this unconditionally selects CONFIG_CRC32 as a builtin. Since
CRC32 is relied upon by core functionality such as CONFIG_OF_FLATTREE,
this just codifies the status quo.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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