Unverified Commit da215b08 authored by Eric Biggers's avatar Eric Biggers Committed by Palmer Dabbelt
Browse files

crypto: riscv - parallelize AES-CBC decryption 



Since CBC decryption is parallelizable, make the RISC-V implementation
of AES-CBC decryption process multiple blocks at a time, instead of
processing the blocks one by one.  This should improve performance.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20240208060851.154129-1-ebiggers@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 028d1aee

arch/riscv/crypto/aes-riscv64-zvkned.S

+15 −9
Original line number Diff line number Diff line
@@ -139,19 +139,25 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) 
.endm



.macro	aes_cbc_decrypt	keylen

	srli		LEN, LEN, 2	// Convert LEN from bytes to words

	vle32.v		v16, (IVP)	// Load IV

1:

	vle32.v		v17, (INP)	// Load ciphertext block

	vmv.v.v		v18, v17	// Save ciphertext block

	aes_decrypt	v17, \keylen	// Decrypt

	vxor.vv		v17, v17, v16	// XOR with IV or prev ciphertext block

	vse32.v		v17, (OUTP)	// Store plaintext block

	vmv.v.v		v16, v18	// Next "IV" is prev ciphertext block

	addi		INP, INP, 16

	addi		OUTP, OUTP, 16

	addi		LEN, LEN, -16

	vsetvli		t0, LEN, e32, m4, ta, ma

	vle32.v		v20, (INP)	// Load ciphertext blocks

	vslideup.vi	v16, v20, 4	// Setup prev ciphertext blocks

	addi		t1, t0, -4

	vslidedown.vx	v24, v20, t1	// Save last ciphertext block

	aes_decrypt	v20, \keylen	// Decrypt the blocks

	vxor.vv		v20, v20, v16	// XOR with prev ciphertext blocks

	vse32.v		v20, (OUTP)	// Store plaintext blocks

	vmv.v.v		v16, v24	// Next "IV" is last ciphertext block

	slli		t1, t0, 2	// Words to bytes

	add		INP, INP, t1

	add		OUTP, OUTP, t1

	sub		LEN, LEN, t0

	bnez		LEN, 1b



	vsetivli	zero, 4, e32, m1, ta, ma

	vse32.v		v16, (IVP)	// Store next IV

	ret

.endm