In preparation of extending the x86 ChaCha driver to also expose the ChaCha
library interface, drop the dependency on the chacha_generic crypto driver
as a non-SIMD fallback, and depend on the generic ChaCha library directly.
This way, we only pull in the code we actually need, without registering
a set of ChaCha skciphers that we will never use.
Since turning the FPU on and off is cheap these days, simplify the SIMD
routine by dropping the per-page yield, which makes for a cleaner switch
to the library API as well. This also allows use to invoke the skcipher
walk routines in non-atomic mode.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/x86/crypto/chacha_glue.c | 90 ++++++++------------
crypto/Kconfig | 2 +-
2 files changed, 36 insertions(+), 56 deletions(-)
diff --git a/arch/x86/crypto/chacha_glue.c b/arch/x86/crypto/chacha_glue.c
index bc62daa8dafd..0aabb382edce 100644
--- a/arch/x86/crypto/chacha_glue.c
+++ b/arch/x86/crypto/chacha_glue.c
@@ -123,37 +123,38 @@ static void chacha_dosimd(u32 *state, u8 *dst, const u8 *src,
}
}
-static int chacha_simd_stream_xor(struct skcipher_walk *walk,
+static int chacha_simd_stream_xor(struct skcipher_request *req,
const struct chacha_ctx *ctx, const u8 *iv)
{
u32 *state, state_buf[16 + 2] __aligned(8);
- int next_yield = 4096; /* bytes until next FPU yield */
- int err = 0;
+ struct skcipher_walk walk;
+ int err;
+
+ err = skcipher_walk_virt(&walk, req, false);
BUILD_BUG_ON(CHACHA_STATE_ALIGN != 16);
state = PTR_ALIGN(state_buf + 0, CHACHA_STATE_ALIGN);
- crypto_chacha_init(state, ctx, iv);
+ chacha_init_generic(state, ctx->key, iv);
- while (walk->nbytes > 0) {
- unsigned int nbytes = walk->nbytes;
+ while (walk.nbytes > 0) {
+ unsigned int nbytes = walk.nbytes;
- if (nbytes < walk->total) {
- nbytes = round_down(nbytes, walk->stride);
- next_yield -= nbytes;
- }
+ if (nbytes < walk.total)
+ nbytes = round_down(nbytes, walk.stride);
- chacha_dosimd(state, walk->dst.virt.addr, walk->src.virt.addr,
- nbytes, ctx->nrounds);
-
- if (next_yield <= 0) {
- /* temporarily allow preemption */
- kernel_fpu_end();
+ if (!crypto_simd_usable()) {
+ chacha_crypt_generic(state, walk.dst.virt.addr,
+ walk.src.virt.addr, nbytes,
+ ctx->nrounds);
+ } else {
kernel_fpu_begin();
- next_yield = 4096;
+ chacha_dosimd(state, walk.dst.virt.addr,
+ walk.src.virt.addr, nbytes,
+ ctx->nrounds);
+ kernel_fpu_end();
}
-
- err = skcipher_walk_done(walk, walk->nbytes - nbytes);
+ err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}
return err;
@@ -163,55 +164,34 @@ static int chacha_simd(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
- struct skcipher_walk walk;
- int err;
- if (req->cryptlen <= CHACHA_BLOCK_SIZE || !crypto_simd_usable())
- return crypto_chacha_crypt(req);
-
- err = skcipher_walk_virt(&walk, req, true);
- if (err)
- return err;
-
- kernel_fpu_begin();
- err = chacha_simd_stream_xor(&walk, ctx, req->iv);
- kernel_fpu_end();
- return err;
+ return chacha_simd_stream_xor(req, ctx, req->iv);
}
static int xchacha_simd(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
- struct skcipher_walk walk;
- struct chacha_ctx subctx;
u32 *state, state_buf[16 + 2] __aligned(8);
+ struct chacha_ctx subctx;
u8 real_iv[16];
- int err;
-
- if (req->cryptlen <= CHACHA_BLOCK_SIZE || !crypto_simd_usable())
- return crypto_xchacha_crypt(req);
-
- err = skcipher_walk_virt(&walk, req, true);
- if (err)
- return err;
BUILD_BUG_ON(CHACHA_STATE_ALIGN != 16);
state = PTR_ALIGN(state_buf + 0, CHACHA_STATE_ALIGN);
- crypto_chacha_init(state, ctx, req->iv);
-
- kernel_fpu_begin();
-
- hchacha_block_ssse3(state, subctx.key, ctx->nrounds);
+ chacha_init_generic(state, ctx->key, req->iv);
+
+ if (req->cryptlen > CHACHA_BLOCK_SIZE && crypto_simd_usable()) {
+ kernel_fpu_begin();
+ hchacha_block_ssse3(state, subctx.key, ctx->nrounds);
+ kernel_fpu_end();
+ } else {
+ hchacha_block_generic(state, subctx.key, ctx->nrounds);
+ }
subctx.nrounds = ctx->nrounds;
memcpy(&real_iv[0], req->iv + 24, 8);
memcpy(&real_iv[8], req->iv + 16, 8);
- err = chacha_simd_stream_xor(&walk, &subctx, real_iv);
-
- kernel_fpu_end();
-
- return err;
+ return chacha_simd_stream_xor(req, &subctx, real_iv);
}
static struct skcipher_alg algs[] = {
@@ -227,7 +207,7 @@ static struct skcipher_alg algs[] = {
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = CHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
- .setkey = crypto_chacha20_setkey,
+ .setkey = chacha20_setkey,
.encrypt = chacha_simd,
.decrypt = chacha_simd,
}, {
@@ -242,7 +222,7 @@ static struct skcipher_alg algs[] = {
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = XCHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
- .setkey = crypto_chacha20_setkey,
+ .setkey = chacha20_setkey,
.encrypt = xchacha_simd,
.decrypt = xchacha_simd,
}, {
@@ -257,7 +237,7 @@ static struct skcipher_alg algs[] = {
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = XCHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
- .setkey = crypto_chacha12_setkey,
+ .setkey = chacha12_setkey,
.encrypt = xchacha_simd,
.decrypt = xchacha_simd,
},
diff --git a/crypto/Kconfig b/crypto/Kconfig
index ae4495ae003f..1abca30ed6ae 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1436,7 +1436,7 @@ config CRYPTO_CHACHA20_X86_64
tristate "ChaCha stream cipher algorithms (x86_64/SSSE3/AVX2/AVX-512VL)"
depends on X86 && 64BIT
select CRYPTO_SKCIPHER
- select CRYPTO_CHACHA20
+ select CRYPTO_LIB_CHACHA_GENERIC
help
SSSE3, AVX2, and AVX-512VL optimized implementations of the ChaCha20,
XChaCha20, and XChaCha12 stream ciphers.
--
2.20.1
