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crypto: riscv/chacha - implement library instead of skcipher

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Currently the RISC-V optimized ChaCha20 is only wired up to the
crypto_skcipher API, which makes it unavailable to users of the library
API.  The crypto_skcipher API for ChaCha20 is going to change to be
implemented on top of the library API, so the library API needs to be
supported.  And of course it's needed anyway to serve the library users.

Therefore, change the RISC-V ChaCha20 code to implement the library API
instead of the crypto_skcipher API.

The library functions take the ChaCha state matrix directly (instead of
key and IV) and support both ChaCha20 and ChaCha12.  To make the RISC-V
code work properly for that, change the assembly code to take the state
matrix directly and add a nrounds parameter.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2025-04-05 11:26:01 -07:00 • committed by Herbert Xu
parent 570ef50a15
commit ceba0eda83
3 changed files with 78 additions and 116 deletions
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11
arch/riscv/crypto/Kconfig
View file

@ -19,14 +19,11 @@ config CRYPTO_AES_RISCV64
- Zvkg vector crypto extension (XTS) - Zvkg vector crypto extension (XTS)
config CRYPTO_CHACHA_RISCV64 config CRYPTO_CHACHA_RISCV64
tristate "Ciphers: ChaCha" tristate
depends on 64BIT && RISCV_ISA_V && TOOLCHAIN_HAS_VECTOR_CRYPTO depends on 64BIT && RISCV_ISA_V && TOOLCHAIN_HAS_VECTOR_CRYPTO
select CRYPTO_SKCIPHER select CRYPTO_ARCH_HAVE_LIB_CHACHA
help select CRYPTO_LIB_CHACHA_GENERIC
Length-preserving ciphers: ChaCha20 stream cipher algorithm default CRYPTO_LIB_CHACHA_INTERNAL
Architecture: riscv64 using:
- Zvkb vector crypto extension
config CRYPTO_GHASH_RISCV64 config CRYPTO_GHASH_RISCV64
tristate "Hash functions: GHASH" tristate "Hash functions: GHASH"

112
arch/riscv/crypto/chacha-riscv64-glue.c
View file

@ -1,6 +1,6 @@
// SPDX-License-Identifier: GPL-2.0-only // SPDX-License-Identifier: GPL-2.0-only
/* /*
* ChaCha20 using the RISC-V vector crypto extensions * ChaCha stream cipher (RISC-V optimized)
* *
* Copyright (C) 2023 SiFive, Inc. * Copyright (C) 2023 SiFive, Inc.
* Author: Jerry Shih <jerry.shih@sifive.com> * Author: Jerry Shih <jerry.shih@sifive.com>
@ -8,94 +8,56 @@
#include <asm/simd.h> #include <asm/simd.h>
#include <asm/vector.h> #include <asm/vector.h>
#include <crypto/internal/chacha.h> #include <crypto/chacha.h>
#include <crypto/internal/skcipher.h> #include <crypto/internal/simd.h>
#include <linux/linkage.h> #include <linux/linkage.h>
#include <linux/module.h> #include <linux/module.h>
asmlinkage void chacha20_zvkb(const u32 key[8], const u8 *in, u8 *out, static __ro_after_init DEFINE_STATIC_KEY_FALSE(use_zvkb);
size_t len, const u32 iv[4]);
static int riscv64_chacha20_crypt(struct skcipher_request *req) asmlinkage void chacha_zvkb(u32 state[16], const u8 *in, u8 *out,
size_t nblocks, int nrounds);
void hchacha_block_arch(const u32 *state, u32 *out, int nrounds)
{ {
u32 iv[CHACHA_IV_SIZE / sizeof(u32)]; hchacha_block_generic(state, out, nrounds);
u8 block_buffer[CHACHA_BLOCK_SIZE];
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
const struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
struct skcipher_walk walk;
unsigned int nbytes;
unsigned int tail_bytes;
int err;
iv[0] = get_unaligned_le32(req->iv);
iv[1] = get_unaligned_le32(req->iv + 4);
iv[2] = get_unaligned_le32(req->iv + 8);
iv[3] = get_unaligned_le32(req->iv + 12);
err = skcipher_walk_virt(&walk, req, false);
while (walk.nbytes) {
nbytes = walk.nbytes & ~(CHACHA_BLOCK_SIZE - 1);
tail_bytes = walk.nbytes & (CHACHA_BLOCK_SIZE - 1);
kernel_vector_begin();
if (nbytes) {
chacha20_zvkb(ctx->key, walk.src.virt.addr,
walk.dst.virt.addr, nbytes, iv);
iv[0] += nbytes / CHACHA_BLOCK_SIZE;
}
if (walk.nbytes == walk.total && tail_bytes > 0) {
memcpy(block_buffer, walk.src.virt.addr + nbytes,
tail_bytes);
chacha20_zvkb(ctx->key, block_buffer, block_buffer,
CHACHA_BLOCK_SIZE, iv);
memcpy(walk.dst.virt.addr + nbytes, block_buffer,
tail_bytes);
tail_bytes = 0;
}
kernel_vector_end();
err = skcipher_walk_done(&walk, tail_bytes);
}
return err;
} }
EXPORT_SYMBOL(hchacha_block_arch);
static struct skcipher_alg riscv64_chacha_alg = { void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, unsigned int bytes,
.setkey = chacha20_setkey, int nrounds)
.encrypt = riscv64_chacha20_crypt, {
.decrypt = riscv64_chacha20_crypt, u8 block_buffer[CHACHA_BLOCK_SIZE];
.min_keysize = CHACHA_KEY_SIZE, unsigned int full_blocks = bytes / CHACHA_BLOCK_SIZE;
.max_keysize = CHACHA_KEY_SIZE, unsigned int tail_bytes = bytes % CHACHA_BLOCK_SIZE;
.ivsize = CHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE, if (!static_branch_likely(&use_zvkb) || !crypto_simd_usable())
.walksize = 4 * CHACHA_BLOCK_SIZE, return chacha_crypt_generic(state, dst, src, bytes, nrounds);
.base = {
.cra_blocksize = 1, kernel_vector_begin();
.cra_ctxsize = sizeof(struct chacha_ctx), if (full_blocks) {
.cra_priority = 300, chacha_zvkb(state, src, dst, full_blocks, nrounds);
.cra_name = "chacha20", src += full_blocks * CHACHA_BLOCK_SIZE;
.cra_driver_name = "chacha20-riscv64-zvkb", dst += full_blocks * CHACHA_BLOCK_SIZE;
.cra_module = THIS_MODULE, }
}, if (tail_bytes) {
}; memcpy(block_buffer, src, tail_bytes);
chacha_zvkb(state, block_buffer, block_buffer, 1, nrounds);
memcpy(dst, block_buffer, tail_bytes);
}
kernel_vector_end();
}
EXPORT_SYMBOL(chacha_crypt_arch);
static int __init riscv64_chacha_mod_init(void) static int __init riscv64_chacha_mod_init(void)
{ {
if (riscv_isa_extension_available(NULL, ZVKB) && if (riscv_isa_extension_available(NULL, ZVKB) &&
riscv_vector_vlen() >= 128) riscv_vector_vlen() >= 128)
return crypto_register_skcipher(&riscv64_chacha_alg); static_branch_enable(&use_zvkb);
return 0;
return -ENODEV;
} }
static void __exit riscv64_chacha_mod_exit(void)
{
crypto_unregister_skcipher(&riscv64_chacha_alg);
}
module_init(riscv64_chacha_mod_init); module_init(riscv64_chacha_mod_init);
module_exit(riscv64_chacha_mod_exit);
MODULE_DESCRIPTION("ChaCha20 (RISC-V accelerated)"); MODULE_DESCRIPTION("ChaCha stream cipher (RISC-V optimized)");
MODULE_AUTHOR("Jerry Shih <jerry.shih@sifive.com>"); MODULE_AUTHOR("Jerry Shih <jerry.shih@sifive.com>");
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("chacha20");

71
arch/riscv/crypto/chacha-riscv64-zvkb.S
View file

@ -46,11 +46,11 @@
.text .text
.option arch, +zvkb .option arch, +zvkb
#define KEYP a0 #define STATEP a0
#define INP a1 #define INP a1
#define OUTP a2 #define OUTP a2
#define LEN a3 #define NBLOCKS a3
#define IVP a4 #define NROUNDS a4
#define CONSTS0 a5 #define CONSTS0 a5
#define CONSTS1 a6 #define CONSTS1 a6
@ -59,7 +59,7 @@
#define TMP t1 #define TMP t1
#define VL t2 #define VL t2
#define STRIDE t3 #define STRIDE t3
#define NROUNDS t4 #define ROUND_CTR t4
#define KEY0 s0 #define KEY0 s0
#define KEY1 s1 #define KEY1 s1
#define KEY2 s2 #define KEY2 s2
@ -132,14 +132,16 @@
vror.vi \b3, \b3, 32 - 7 vror.vi \b3, \b3, 32 - 7
.endm .endm
// void chacha20_zvkb(const u32 key[8], const u8 *in, u8 *out, size_t len, // void chacha_zvkb(u32 state[16], const u8 *in, u8 *out, size_t nblocks,
// const u32 iv[4]); // int nrounds);
// //
// |len| must be nonzero and a multiple of 64 (CHACHA_BLOCK_SIZE). // |nblocks| is the number of 64-byte blocks to process, and must be nonzero.
// The counter is treated as 32-bit, following the RFC7539 convention. //
SYM_FUNC_START(chacha20_zvkb) // |state| gives the ChaCha state matrix, including the 32-bit counter in
srli LEN, LEN, 6 // Bytes to blocks // state[12] following the RFC7539 convention; note that this differs from the
// original Salsa20 paper which uses a 64-bit counter in state[12..13]. The
// updated 32-bit counter is written back to state[12] before returning.
SYM_FUNC_START(chacha_zvkb)
addi sp, sp, -96 addi sp, sp, -96
sd s0, 0(sp) sd s0, 0(sp)
sd s1, 8(sp) sd s1, 8(sp)
@ -157,26 +159,26 @@ SYM_FUNC_START(chacha20_zvkb)
li STRIDE, 64 li STRIDE, 64
// Set up the initial state matrix in scalar registers. // Set up the initial state matrix in scalar registers.
li CONSTS0, 0x61707865 // "expa" little endian lw CONSTS0, 0(STATEP)
li CONSTS1, 0x3320646e // "nd 3" little endian lw CONSTS1, 4(STATEP)
li CONSTS2, 0x79622d32 // "2-by" little endian lw CONSTS2, 8(STATEP)
li CONSTS3, 0x6b206574 // "te k" little endian lw CONSTS3, 12(STATEP)
lw KEY0, 0(KEYP) lw KEY0, 16(STATEP)
lw KEY1, 4(KEYP) lw KEY1, 20(STATEP)
lw KEY2, 8(KEYP) lw KEY2, 24(STATEP)
lw KEY3, 12(KEYP) lw KEY3, 28(STATEP)
lw KEY4, 16(KEYP) lw KEY4, 32(STATEP)
lw KEY5, 20(KEYP) lw KEY5, 36(STATEP)
lw KEY6, 24(KEYP) lw KEY6, 40(STATEP)
lw KEY7, 28(KEYP) lw KEY7, 44(STATEP)
lw COUNTER, 0(IVP) lw COUNTER, 48(STATEP)
lw NONCE0, 4(IVP) lw NONCE0, 52(STATEP)
lw NONCE1, 8(IVP) lw NONCE1, 56(STATEP)
lw NONCE2, 12(IVP) lw NONCE2, 60(STATEP)
.Lblock_loop: .Lblock_loop:
// Set vl to the number of blocks to process in this iteration. // Set vl to the number of blocks to process in this iteration.
vsetvli VL, LEN, e32, m1, ta, ma vsetvli VL, NBLOCKS, e32, m1, ta, ma
// Set up the initial state matrix for the next VL blocks in v0-v15. // Set up the initial state matrix for the next VL blocks in v0-v15.
// v{i} holds the i'th 32-bit word of the state matrix for all blocks. // v{i} holds the i'th 32-bit word of the state matrix for all blocks.
@ -203,16 +205,16 @@ SYM_FUNC_START(chacha20_zvkb)
// v{16+i} holds the i'th 32-bit word for all blocks. // v{16+i} holds the i'th 32-bit word for all blocks.
vlsseg8e32.v v16, (INP), STRIDE vlsseg8e32.v v16, (INP), STRIDE
li NROUNDS, 20 mv ROUND_CTR, NROUNDS
.Lnext_doubleround: .Lnext_doubleround:
addi NROUNDS, NROUNDS, -2 addi ROUND_CTR, ROUND_CTR, -2
// column round // column round
chacha_round v0, v4, v8, v12, v1, v5, v9, v13, \ chacha_round v0, v4, v8, v12, v1, v5, v9, v13, \
v2, v6, v10, v14, v3, v7, v11, v15 v2, v6, v10, v14, v3, v7, v11, v15
// diagonal round // diagonal round
chacha_round v0, v5, v10, v15, v1, v6, v11, v12, \ chacha_round v0, v5, v10, v15, v1, v6, v11, v12, \
v2, v7, v8, v13, v3, v4, v9, v14 v2, v7, v8, v13, v3, v4, v9, v14
bnez NROUNDS, .Lnext_doubleround bnez ROUND_CTR, .Lnext_doubleround
// Load the second half of the input data for each block into v24-v31. // Load the second half of the input data for each block into v24-v31.
// v{24+i} holds the {8+i}'th 32-bit word for all blocks. // v{24+i} holds the {8+i}'th 32-bit word for all blocks.
@ -271,12 +273,13 @@ SYM_FUNC_START(chacha20_zvkb)
// Update the counter, the remaining number of blocks, and the input and // Update the counter, the remaining number of blocks, and the input and
// output pointers according to the number of blocks processed (VL). // output pointers according to the number of blocks processed (VL).
add COUNTER, COUNTER, VL add COUNTER, COUNTER, VL
sub LEN, LEN, VL sub NBLOCKS, NBLOCKS, VL
slli TMP, VL, 6 slli TMP, VL, 6
add OUTP, OUTP, TMP add OUTP, OUTP, TMP
add INP, INP, TMP add INP, INP, TMP
bnez LEN, .Lblock_loop bnez NBLOCKS, .Lblock_loop
sw COUNTER, 48(STATEP)
ld s0, 0(sp) ld s0, 0(sp)
ld s1, 8(sp) ld s1, 8(sp)
ld s2, 16(sp) ld s2, 16(sp)
@ -291,4 +294,4 @@ SYM_FUNC_START(chacha20_zvkb)
ld s11, 88(sp) ld s11, 88(sp)
addi sp, sp, 96 addi sp, sp, 96
ret ret
SYM_FUNC_END(chacha20_zvkb) SYM_FUNC_END(chacha_zvkb)