crypto: arm64/chacha - expose arm64 ChaCha routine as library function

Expose the accelerated NEON ChaCha routine directly as a symbol
export so that users of the ChaCha library API can use it directly.

Given that calls into the library API will always go through the
routines in this module if it is enabled, switch to static keys
to select the optimal implementation available (which may be none
at all, in which case we defer to the generic implementation for
all invocations).

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index 22c6642ae4648f58fc1f2bbee12afeb3b2fdb4cc..ffb827b84d6c4cfbb87abc4cfa6c69338353ae51 100644 (file)
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -104,6 +104,7 @@ config CRYPTO_CHACHA20_NEON
        depends on KERNEL_MODE_NEON
        select CRYPTO_SKCIPHER
        select CRYPTO_LIB_CHACHA_GENERIC
+       select CRYPTO_ARCH_HAVE_LIB_CHACHA
 
 config CRYPTO_NHPOLY1305_NEON
        tristate "NHPoly1305 hash function using NEON instructions (for Adiantum)"

diff --git a/arch/arm64/crypto/chacha-neon-glue.c b/arch/arm64/crypto/chacha-neon-glue.c
index cae2cb92eca86dab50082206f4e7c58e5fff228e..46cd4297761c1638e6e30675507a65a721e7798f 100644 (file)
--- a/arch/arm64/crypto/chacha-neon-glue.c
+++ b/arch/arm64/crypto/chacha-neon-glue.c
@@ -23,6 +23,7 @@
 #include <crypto/internal/chacha.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
+#include <linux/jump_label.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 
@@ -36,6 +37,8 @@ asmlinkage void chacha_4block_xor_neon(u32 *state, u8 *dst, const u8 *src,
                                       int nrounds, int bytes);
 asmlinkage void hchacha_block_neon(const u32 *state, u32 *out, int nrounds);
 
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
+
 static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
                          int bytes, int nrounds)
 {
@@ -59,6 +62,37 @@ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
        }
 }
 
+void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
+{
+       if (!static_branch_likely(&have_neon) || !crypto_simd_usable()) {
+               hchacha_block_generic(state, stream, nrounds);
+       } else {
+               kernel_neon_begin();
+               hchacha_block_neon(state, stream, nrounds);
+               kernel_neon_end();
+       }
+}
+EXPORT_SYMBOL(hchacha_block_arch);
+
+void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
+{
+       chacha_init_generic(state, key, iv);
+}
+EXPORT_SYMBOL(chacha_init_arch);
+
+void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, unsigned int bytes,
+                      int nrounds)
+{
+       if (!static_branch_likely(&have_neon) || bytes <= CHACHA_BLOCK_SIZE ||
+           !crypto_simd_usable())
+               return chacha_crypt_generic(state, dst, src, bytes, nrounds);
+
+       kernel_neon_begin();
+       chacha_doneon(state, dst, src, bytes, nrounds);
+       kernel_neon_end();
+}
+EXPORT_SYMBOL(chacha_crypt_arch);
+
 static int chacha_neon_stream_xor(struct skcipher_request *req,
                                  const struct chacha_ctx *ctx, const u8 *iv)
 {
@@ -76,7 +110,8 @@ static int chacha_neon_stream_xor(struct skcipher_request *req,
                if (nbytes < walk.total)
                        nbytes = rounddown(nbytes, walk.stride);
 
-               if (!crypto_simd_usable()) {
+               if (!static_branch_likely(&have_neon) ||
+                   !crypto_simd_usable()) {
                        chacha_crypt_generic(state, walk.dst.virt.addr,
                                             walk.src.virt.addr, nbytes,
                                             ctx->nrounds);
@@ -109,14 +144,7 @@ static int xchacha_neon(struct skcipher_request *req)
        u8 real_iv[16];
 
        chacha_init_generic(state, ctx->key, req->iv);
-
-       if (crypto_simd_usable()) {
-               kernel_neon_begin();
-               hchacha_block_neon(state, subctx.key, ctx->nrounds);
-               kernel_neon_end();
-       } else {
-               hchacha_block_generic(state, subctx.key, ctx->nrounds);
-       }
+       hchacha_block_arch(state, subctx.key, ctx->nrounds);
        subctx.nrounds = ctx->nrounds;
 
        memcpy(&real_iv[0], req->iv + 24, 8);
@@ -179,14 +207,17 @@ static struct skcipher_alg algs[] = {
 static int __init chacha_simd_mod_init(void)
 {
        if (!cpu_have_named_feature(ASIMD))
-               return -ENODEV;
+               return 0;
+
+       static_branch_enable(&have_neon);
 
        return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
 }
 
 static void __exit chacha_simd_mod_fini(void)
 {
-       crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
+       if (cpu_have_named_feature(ASIMD))
+               crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
 }
 
 module_init(chacha_simd_mod_init);