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The assembly code that does all 80 rounds of SHA-1 is highly repetitive.
Replace it with 20 expansions of a macro that does 4 rounds, using the
macro arguments and .if directives to handle the slight variations
between rounds. This reduces the length of sha1-ni-asm.S by 129 lines
while still producing the exact same object file. This mirrors
sha256-ni-asm.S which uses this same strategy.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250718191900.42877-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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- Store the previous state in %xmm8-%xmm9 instead of spilling it to the
stack. There are plenty of unused XMM registers here, so there is no
reason to spill to the stack. (While 32-bit code is limited to
%xmm0-%xmm7, this is 64-bit code, so it's free to use %xmm8-%xmm15.)
- Remove the unnecessary check for nblocks == 0. sha1_ni_transform() is
always passed a positive nblocks.
- To get an XMM register with 'e' in the high dword and the rest zeroes,
just zeroize the register using pxor, then load 'e'. Previously the
code loaded 'e', then zeroized the lower dwords by AND-ing with a
constant, which was slightly less efficient.
- Instead of computing &DATA_PTR[NBLOCKS << 6] and stopping when
DATA_PTR reaches that value, instead just decrement NBLOCKS on each
iteration and stop when it reaches 0. This is fewer instructions.
- Rename DIGEST_PTR to STATE_PTR. It points to the SHA-1 internal
state, not a SHA-1 digest value.
This commit shrinks the code size of sha1_ni_transform() from 624 bytes
to 589 bytes and also shrinks rodata by 16 bytes.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250718191900.42877-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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Instead of exposing the x86-optimized SHA-1 code via x86-specific
crypto_shash algorithms, instead just implement the sha1_blocks()
library function. This is much simpler, it makes the SHA-1 library
functions be x86-optimized, and it fixes the longstanding issue where
the x86-optimized SHA-1 code was disabled by default. SHA-1 still
remains available through crypto_shash, but individual architectures no
longer need to handle it.
To match sha1_blocks(), change the type of the nblocks parameter of the
assembly functions from int to size_t. The assembly functions actually
already treated it as size_t.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250712232329.818226-14-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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