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Commit cf862cbc authored by Stephan Mueller's avatar Stephan Mueller Committed by Herbert Xu
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crypto: drbg - eliminate constant reinitialization of SGL 



The CTR DRBG requires two SGLs pointing to input/output buffers for the
CTR AES operation. The used SGLs always have only one entry. Thus, the
SGL can be initialized during allocation time, preventing a
re-initialization of the SGLs during each call.

The performance is increased by about 1 to 3 percent depending on the
size of the requested buffer size.

Signed-off-by: default avatarStephan Mueller <smueller@chronox.de>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 3fd8093b

crypto/drbg.c

+7 −4
Original line number Diff line number Diff line
@@ -1715,6 +1715,9 @@ static int drbg_init_sym_kernel(struct drbg_state *drbg) 
	drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,

					      alignmask + 1);



	sg_init_table(&drbg->sg_in, 1);

	sg_init_table(&drbg->sg_out, 1);



	return alignmask;

}
@@ -1743,17 +1746,17 @@ static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, 
			      u8 *inbuf, u32 inlen,

			      u8 *outbuf, u32 outlen)

{

	struct scatterlist sg_in, sg_out;

	struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;

	int ret;



	sg_init_one(&sg_in, inbuf, inlen);

	sg_init_one(&sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);

	sg_set_buf(sg_in, inbuf, inlen);

	sg_set_buf(sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);



	while (outlen) {

		u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);



		/* Output buffer may not be valid for SGL, use scratchpad */

		skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,

		skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,

					   cryptlen, drbg->V);

		ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),

					&drbg->ctr_wait);

include/crypto/drbg.h

+1 −0
Original line number Diff line number Diff line
@@ -127,6 +127,7 @@ struct drbg_state { 
	__u8 *outscratchpadbuf;			/* CTR mode output scratchpad */

        __u8 *outscratchpad;			/* CTR mode aligned outbuf */

	struct crypto_wait ctr_wait;		/* CTR mode async wait obj */

	struct scatterlist sg_in, sg_out;	/* CTR mode SGLs */



	bool seeded;		/* DRBG fully seeded? */

	bool pr;		/* Prediction resistance enabled? */