The only remaining user of the fallback implementation of 64x64
polynomial multiplication using 8x8 PMULL instructions is the final
reduction from a 16 byte vector to a 16-bit CRC.
The fallback code is complicated and messy, and this reduction has
little impact on the overall performance, so instead, let's calculate
the final CRC by passing the 16 byte vector to the generic CRC-T10DIF
implementation when running the fallback version.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The CRC-T10DIF implementation for arm64 has a version that uses 8x8
polynomial multiplication, for cores that lack the crypto extensions,
which cover the 64x64 polynomial multiplication instruction that the
algorithm was built around.
This fallback version rather naively adopted the 64x64 polynomial
multiplication algorithm that I ported from ARM for the GHASH driver,
which needs 8 PMULL8 instructions to implement one PMULL64. This is
reasonable, given that each 8-bit vector element needs to be multiplied
with each element in the other vector, producing 8 vectors with partial
results that need to be combined to yield the correct result.
However, most PMULL64 invocations in the CRC-T10DIF code involve
multiplication by a pair of 16-bit folding coefficients, and so all the
partial results from higher order bytes will be zero, and there is no
need to calculate them to begin with.
Then, the CRC-T10DIF algorithm always XORs the output values of the
PMULL64 instructions being issued in pairs, and so there is no need to
faithfully implement each individual PMULL64 instruction, as long as
XORing the results pairwise produces the expected result.
Implementing these improvements results in a speedup of 3.3x on low-end
platforms such as Raspberry Pi 4 (Cortex-A72)
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use the frame_push and frame_pop macros to set up the stack frame so
that return address protections will be enabled automically when
configured.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Instead of yielding from the bowels of the asm routine if a reschedule
is needed, divide up the input into 4 KB chunks in the C glue. This
simplifies the code substantially, and avoids scheduling out the task
with the asm routine on the call stack, which is undesirable from a
CFI/instrumentation point of view.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently most of the crypto files enable the crypto extension using the
.arch directive but crct10dif-ce-core.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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 crypto code to the
new macros.
There are a small number of files imported from OpenSSL where the assembly
is generated using perl programs, these are not currently annotated at all
and have not been modified.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The x86, arm, and arm64 asm implementations of crct10dif are very
difficult to understand partly because many of the comments, labels, and
macros are named incorrectly: the lengths mentioned are usually off by a
factor of two from the actual code. Many other things are unnecessarily
convoluted as well, e.g. there are many more fold constants than
actually needed and some aren't fully reduced.
This series therefore cleans up all these implementations to be much
more maintainable. I also made some small optimizations where I saw
opportunities, resulting in slightly better performance.
This patch cleans up the arm64 version.
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Remove some code that is no longer called now that we make sure never
to invoke the SIMD routine with less than 16 bytes of input.
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The arm64 implementation of the CRC-T10DIF algorithm uses the 64x64 bit
polynomial multiplication instructions, which are optional in the
architecture, and if these instructions are not available, we fall back
to the C routine which is slow and inefficient.
So let's reuse the 64x64 bit PMULL alternative from the GHASH driver that
uses a sequence of ~40 instructions involving 8x8 bit PMULL and some
shifting and masking. This is a lot slower than the original, but it is
still twice as fast as the current [unoptimized] C code on Cortex-A53,
and it is time invariant and much easier on the D-cache.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reorganize the CRC-T10DIF asm routine so we can easily instantiate an
alternative version based on 8x8 polynomial multiplication in a
subsequent patch.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Avoid excessive scheduling delays under a preemptible kernel by
yielding the NEON after every block of input.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Move the CRC-T10DIF literal data to the .rodata section where it is
safe from being exploited by speculative execution.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This is a transliteration of the Intel algorithm implemented
using SSE and PCLMULQDQ instructions that resides in the file
arch/x86/crypto/crct10dif-pcl-asm_64.S, but simplified to only
operate on buffers that are 16 byte aligned (but of any size)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
