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Message-ID: <20250718191900.42877-2-ebiggers@kernel.org> Date: Fri, 18 Jul 2025 12:18:59 -0700 From: Eric Biggers <ebiggers@...nel.org> To: linux-crypto@...r.kernel.org Cc: linux-kernel@...r.kernel.org, x86@...nel.org, Ard Biesheuvel <ardb@...nel.org>, "Jason A . Donenfeld" <Jason@...c4.com>, Eric Biggers <ebiggers@...nel.org> Subject: [PATCH 1/2] lib/crypto: x86/sha1-ni: Minor optimizations and cleanup - 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. Signed-off-by: Eric Biggers <ebiggers@...nel.org> --- lib/crypto/x86/sha1-ni-asm.S | 68 +++++++++++++----------------------- 1 file changed, 25 insertions(+), 43 deletions(-) diff --git a/lib/crypto/x86/sha1-ni-asm.S b/lib/crypto/x86/sha1-ni-asm.S index 3989b0642ff5f..1d08b2f364ce7 100644 --- a/lib/crypto/x86/sha1-ni-asm.S +++ b/lib/crypto/x86/sha1-ni-asm.S @@ -53,65 +53,56 @@ * */ #include <linux/linkage.h> -#define DIGEST_PTR %rdi /* 1st arg */ +#define STATE_PTR %rdi /* 1st arg */ #define DATA_PTR %rsi /* 2nd arg */ #define NUM_BLKS %rdx /* 3rd arg */ -/* gcc conversion */ -#define FRAME_SIZE 32 /* space for 2x16 bytes */ - #define ABCD %xmm0 #define E0 %xmm1 /* Need two E's b/c they ping pong */ #define E1 %xmm2 #define MSG0 %xmm3 #define MSG1 %xmm4 #define MSG2 %xmm5 #define MSG3 %xmm6 #define SHUF_MASK %xmm7 - +#define ABCD_SAVED %xmm8 +#define E0_SAVED %xmm9 /* * Intel SHA Extensions optimized implementation of a SHA-1 block function * * This function takes a pointer to the current SHA-1 state, a pointer to the - * input data, and the number of 64-byte blocks to process. Once all blocks - * have been processed, the state is updated with the new state. This function - * only processes complete blocks. State initialization, buffering of partial + * input data, and the number of 64-byte blocks to process. The number of + * blocks to process is assumed to be nonzero. Once all blocks have been + * processed, the state is updated with the new state. This function only + * processes complete blocks. State initialization, buffering of partial * blocks, and digest finalization are expected to be handled elsewhere. * * The indented lines in the loop are instructions related to rounds processing. * The non-indented lines are instructions related to the message schedule. * * void sha1_ni_transform(struct sha1_block_state *state, * const u8 *data, size_t nblocks) */ .text SYM_FUNC_START(sha1_ni_transform) - push %rbp - mov %rsp, %rbp - sub $FRAME_SIZE, %rsp - and $~0xF, %rsp - - shl $6, NUM_BLKS /* convert to bytes */ - jz .Ldone_hash - add DATA_PTR, NUM_BLKS /* pointer to end of data */ - - /* load initial hash values */ - pinsrd $3, 1*16(DIGEST_PTR), E0 - movdqu 0*16(DIGEST_PTR), ABCD - pand UPPER_WORD_MASK(%rip), E0 + + /* Load the initial state from STATE_PTR. */ + pxor E0, E0 + pinsrd $3, 16(STATE_PTR), E0 + movdqu (STATE_PTR), ABCD pshufd $0x1B, ABCD, ABCD movdqa PSHUFFLE_BYTE_FLIP_MASK(%rip), SHUF_MASK -.Lloop0: - /* Save hash values for addition after rounds */ - movdqa E0, (0*16)(%rsp) - movdqa ABCD, (1*16)(%rsp) +.Lnext_block: + /* Save the state for addition after the rounds. */ + movdqa E0, E0_SAVED + movdqa ABCD, ABCD_SAVED /* Rounds 0-3 */ movdqu 0*16(DATA_PTR), MSG0 pshufb SHUF_MASK, MSG0 paddd MSG0, E0 @@ -265,35 +256,26 @@ SYM_FUNC_START(sha1_ni_transform) /* Rounds 76-79 */ sha1nexte MSG3, E1 movdqa ABCD, E0 sha1rnds4 $3, E1, ABCD - /* Add current hash values with previously saved */ - sha1nexte (0*16)(%rsp), E0 - paddd (1*16)(%rsp), ABCD + /* Add the previous state (before the rounds) to the current state. */ + sha1nexte E0_SAVED, E0 + paddd ABCD_SAVED, ABCD - /* Increment data pointer and loop if more to process */ + /* Advance to the next block, or break if there are no more blocks. */ add $64, DATA_PTR - cmp NUM_BLKS, DATA_PTR - jne .Lloop0 + dec NUM_BLKS + jnz .Lnext_block - /* Write hash values back in the correct order */ + /* Store the new state to STATE_PTR. */ + pextrd $3, E0, 16(STATE_PTR) pshufd $0x1B, ABCD, ABCD - movdqu ABCD, 0*16(DIGEST_PTR) - pextrd $3, E0, 1*16(DIGEST_PTR) - -.Ldone_hash: - mov %rbp, %rsp - pop %rbp + movdqu ABCD, (STATE_PTR) RET SYM_FUNC_END(sha1_ni_transform) .section .rodata.cst16.PSHUFFLE_BYTE_FLIP_MASK, "aM", @progbits, 16 .align 16 PSHUFFLE_BYTE_FLIP_MASK: .octa 0x000102030405060708090a0b0c0d0e0f - -.section .rodata.cst16.UPPER_WORD_MASK, "aM", @progbits, 16 -.align 16 -UPPER_WORD_MASK: - .octa 0xFFFFFFFF000000000000000000000000 -- 2.50.1
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