Rather than accessing 'alg' directly to avoid the aliasing issue
which leads to unnecessary reloads, use the __restrict keyword
to explicitly tell the compiler that there is no aliasing.
This generates equivalent if not superior code on x86 with gcc 12.
Note that in skcipher_walk_virt the alg assignment is moved after
might_sleep_if because that function is a compiler barrier and
forces a reload.
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index cdf0f11c7eaa..561aa5cc4ffa 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -306,14 +306,16 @@ static int skcipher_walk_first(struct skcipher_walk *walk)
return skcipher_walk_next(walk);
}
-int skcipher_walk_virt(struct skcipher_walk *walk,
- struct skcipher_request *req, bool atomic)
+int skcipher_walk_virt(struct skcipher_walk *__restrict walk,
+ struct skcipher_request *__restrict req, bool atomic)
{
- const struct skcipher_alg *alg =
- crypto_skcipher_alg(crypto_skcipher_reqtfm(req));
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct skcipher_alg *alg;
might_sleep_if(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
+ alg = crypto_skcipher_alg(tfm);
+
walk->total = req->cryptlen;
walk->nbytes = 0;
walk->iv = req->iv;
@@ -329,14 +331,9 @@ int skcipher_walk_virt(struct skcipher_walk *walk,
scatterwalk_start(&walk->in, req->src);
scatterwalk_start(&walk->out, req->dst);
- /*
- * Accessing 'alg' directly generates better code than using the
- * crypto_skcipher_blocksize() and similar helper functions here, as it
- * prevents the algorithm pointer from being repeatedly reloaded.
- */
- walk->blocksize = alg->base.cra_blocksize;
- walk->ivsize = alg->co.ivsize;
- walk->alignmask = alg->base.cra_alignmask;
+ walk->blocksize = crypto_skcipher_blocksize(tfm);
+ walk->ivsize = crypto_skcipher_ivsize(tfm);
+ walk->alignmask = crypto_skcipher_alignmask(tfm);
if (alg->co.base.cra_type != &crypto_skcipher_type)
walk->stride = alg->co.chunksize;
@@ -347,10 +344,11 @@ int skcipher_walk_virt(struct skcipher_walk *walk,
}
EXPORT_SYMBOL_GPL(skcipher_walk_virt);
-static int skcipher_walk_aead_common(struct skcipher_walk *walk,
- struct aead_request *req, bool atomic)
+static int skcipher_walk_aead_common(struct skcipher_walk *__restrict walk,
+ struct aead_request *__restrict req,
+ bool atomic)
{
- const struct aead_alg *alg = crypto_aead_alg(crypto_aead_reqtfm(req));
+ struct crypto_aead *tfm = crypto_aead_reqtfm(req);
walk->nbytes = 0;
walk->iv = req->iv;
@@ -372,21 +370,17 @@ static int skcipher_walk_aead_common(struct skcipher_walk *walk,
scatterwalk_done(&walk->in, 0, walk->total);
scatterwalk_done(&walk->out, 0, walk->total);
- /*
- * Accessing 'alg' directly generates better code than using the
- * crypto_aead_blocksize() and similar helper functions here, as it
- * prevents the algorithm pointer from being repeatedly reloaded.
- */
- walk->blocksize = alg->base.cra_blocksize;
- walk->stride = alg->chunksize;
- walk->ivsize = alg->ivsize;
- walk->alignmask = alg->base.cra_alignmask;
+ walk->blocksize = crypto_aead_blocksize(tfm);
+ walk->stride = crypto_aead_chunksize(tfm);
+ walk->ivsize = crypto_aead_ivsize(tfm);
+ walk->alignmask = crypto_aead_alignmask(tfm);
return skcipher_walk_first(walk);
}
-int skcipher_walk_aead_encrypt(struct skcipher_walk *walk,
- struct aead_request *req, bool atomic)
+int skcipher_walk_aead_encrypt(struct skcipher_walk *__restrict walk,
+ struct aead_request *__restrict req,
+ bool atomic)
{
walk->total = req->cryptlen;
@@ -394,8 +388,9 @@ int skcipher_walk_aead_encrypt(struct skcipher_walk *walk,
}
EXPORT_SYMBOL_GPL(skcipher_walk_aead_encrypt);
-int skcipher_walk_aead_decrypt(struct skcipher_walk *walk,
- struct aead_request *req, bool atomic)
+int skcipher_walk_aead_decrypt(struct skcipher_walk *__restrict walk,
+ struct aead_request *__restrict req,
+ bool atomic)
{
struct crypto_aead *tfm = crypto_aead_reqtfm(req);
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
index 4f49621d3eb6..d6ae7a86fed2 100644
--- a/include/crypto/internal/skcipher.h
+++ b/include/crypto/internal/skcipher.h
@@ -197,13 +197,15 @@ int lskcipher_register_instance(struct crypto_template *tmpl,
struct lskcipher_instance *inst);
int skcipher_walk_done(struct skcipher_walk *walk, int res);
-int skcipher_walk_virt(struct skcipher_walk *walk,
- struct skcipher_request *req,
+int skcipher_walk_virt(struct skcipher_walk *__restrict walk,
+ struct skcipher_request *__restrict req,
bool atomic);
-int skcipher_walk_aead_encrypt(struct skcipher_walk *walk,
- struct aead_request *req, bool atomic);
-int skcipher_walk_aead_decrypt(struct skcipher_walk *walk,
- struct aead_request *req, bool atomic);
+int skcipher_walk_aead_encrypt(struct skcipher_walk *__restrict walk,
+ struct aead_request *__restrict req,
+ bool atomic);
+int skcipher_walk_aead_decrypt(struct skcipher_walk *__restrict walk,
+ struct aead_request *__restrict req,
+ bool atomic);
static inline void skcipher_walk_abort(struct skcipher_walk *walk)
{
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
