From 08debaa5cb31da50725a8cb2f06d3f617a9caa98 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Wed, 18 Oct 2023 15:34:55 -0700
Subject: [PATCH] crypto: shash - eliminate indirect call for default import
and export
Most shash algorithms don't have custom ->import and ->export functions,
resulting in the memcpy() based default being used. Yet,
crypto_shash_import() and crypto_shash_export() still make an indirect
call, which is expensive. Therefore, change how the default import and
export are called to make it so that crypto_shash_import() and
crypto_shash_export() don't do an indirect call in this case.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
crypto/shash.c | 41 +++++++++++++++++++++++++++++++++--------
include/crypto/hash.h | 15 ++-------------
2 files changed, 35 insertions(+), 21 deletions(-)
diff --git a/crypto/shash.c b/crypto/shash.c
index 15fee57cca8ef..52420c41db44a 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -277,17 +277,34 @@ int crypto_shash_tfm_digest(struct crypto_shash *tfm, const u8 *data,
}
EXPORT_SYMBOL_GPL(crypto_shash_tfm_digest);
-static int shash_default_export(struct shash_desc *desc, void *out)
+int crypto_shash_export(struct shash_desc *desc, void *out)
{
- memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm));
+ struct crypto_shash *tfm = desc->tfm;
+ struct shash_alg *shash = crypto_shash_alg(tfm);
+
+ if (shash->export)
+ return shash->export(desc, out);
+
+ memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(tfm));
return 0;
}
+EXPORT_SYMBOL_GPL(crypto_shash_export);
-static int shash_default_import(struct shash_desc *desc, const void *in)
+int crypto_shash_import(struct shash_desc *desc, const void *in)
{
- memcpy(shash_desc_ctx(desc), in, crypto_shash_descsize(desc->tfm));
+ struct crypto_shash *tfm = desc->tfm;
+ struct shash_alg *shash = crypto_shash_alg(tfm);
+
+ if (crypto_shash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
+ return -ENOKEY;
+
+ if (shash->import)
+ return shash->import(desc, in);
+
+ memcpy(shash_desc_ctx(desc), in, crypto_shash_descsize(tfm));
return 0;
}
+EXPORT_SYMBOL_GPL(crypto_shash_import);
static int shash_async_setkey(struct crypto_ahash *tfm, const u8 *key,
unsigned int keylen)
@@ -666,15 +683,23 @@ static int shash_prepare_alg(struct shash_alg *alg)
base->cra_type = &crypto_shash_type;
base->cra_flags |= CRYPTO_ALG_TYPE_SHASH;
+ /*
+ * Handle missing optional functions. For each one we can either
+ * install a default here, or we can leave the pointer as NULL and check
+ * the pointer for NULL in crypto_shash_*(), avoiding an indirect call
+ * when the default behavior is desired. For ->finup and ->digest we
+ * install defaults, since for optimal performance algorithms should
+ * implement these anyway. On the other hand, for ->import and
+ * ->export the common case and best performance comes from the simple
+ * memcpy of the shash_desc_ctx, so when those pointers are NULL we
+ * leave them NULL and provide the memcpy with no indirect call.
+ */
if (!alg->finup)
alg->finup = shash_default_finup;
if (!alg->digest)
alg->digest = shash_default_digest;
- if (!alg->export) {
- alg->export = shash_default_export;
- alg->import = shash_default_import;
+ if (!alg->export)
alg->halg.statesize = alg->descsize;
- }
if (!alg->setkey)
alg->setkey = shash_no_setkey;
diff --git a/include/crypto/hash.h b/include/crypto/hash.h
index f7c2a22cd776d..52e57e93b2f59 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h
@@ -952,10 +952,7 @@ int crypto_shash_tfm_digest(struct crypto_shash *tfm, const u8 *data,
* Context: Any context.
* Return: 0 if the export creation was successful; < 0 if an error occurred
*/
-static inline int crypto_shash_export(struct shash_desc *desc, void *out)
-{
- return crypto_shash_alg(desc->tfm)->export(desc, out);
-}
+int crypto_shash_export(struct shash_desc *desc, void *out);
/**
* crypto_shash_import() - import operational state
@@ -969,15 +966,7 @@ static inline int crypto_shash_export(struct shash_desc *desc, void *out)
* Context: Any context.
* Return: 0 if the import was successful; < 0 if an error occurred
*/
-static inline int crypto_shash_import(struct shash_desc *desc, const void *in)
-{
- struct crypto_shash *tfm = desc->tfm;
-
- if (crypto_shash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
- return -ENOKEY;
-
- return crypto_shash_alg(tfm)->import(desc, in);
-}
+int crypto_shash_import(struct shash_desc *desc, const void *in);
/**
* crypto_shash_init() - (re)initialize message digest
--
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