From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: [RFC PATCH] crypto: algapi - make crypto_xor() and crypto_inc() alignment agnostic Date: Mon, 30 Jan 2017 14:11:29 +0000 Message-ID: <1485785489-5116-1-git-send-email-ard.biesheuvel@linaro.org> Cc: Ard Biesheuvel To: linux-crypto@vger.kernel.org, herbert@gondor.apana.org.au Return-path: Received: from mail-wm0-f50.google.com ([74.125.82.50]:36524 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932109AbdA3OLp (ORCPT ); Mon, 30 Jan 2017 09:11:45 -0500 Received: by mail-wm0-f50.google.com with SMTP id c85so216232861wmi.1 for ; Mon, 30 Jan 2017 06:11:44 -0800 (PST) Sender: linux-crypto-owner@vger.kernel.org List-ID: Instead of unconditionally forcing 4 byte alignment for all generic chaining modes that rely on crypto_xor() or crypto_inc() (which may result in unnecessary copying of data when the underlying hardware can perform unaligned accesses efficiently), make those functions deal with unaligned input explicitly, but only if the Kconfig symbol HAVE_EFFICIENT_UNALIGNED_ACCESS is set. This will allow us to drop the alignmasks from the CBC, CMAC, CTR, CTS, PCBC and SEQIV drivers. For crypto_inc(), this simply involves making the 4-byte stride conditional on HAVE_EFFICIENT_UNALIGNED_ACCESS being set, given that it typically operates on 16 byte buffers. For crypto_xor(), an algorithm is implemented that simply runs through the input using the largest strides possible if unaligned accesses are allowed. If they are not, an optimal sequence of memory accesses is emitted that takes the relative alignment of the input buffers into account, e.g., if the relative misalignment of dst and src is 4 bytes, the entire xor operation will be completed using 4 byte loads and stores (modulo unaligned bits at the start and end). Note that all expressions involving startalign and misalign are simply eliminated by the compiler if HAVE_EFFICIENT_UNALIGNED_ACCESS is defined. Signed-off-by: Ard Biesheuvel --- crypto/algapi.c | 102 ++++++++++++++++---- crypto/cbc.c | 3 - crypto/cmac.c | 3 +- crypto/ctr.c | 2 +- crypto/cts.c | 3 - crypto/pcbc.c | 3 - crypto/seqiv.c | 2 - 7 files changed, 87 insertions(+), 31 deletions(-) diff --git a/crypto/algapi.c b/crypto/algapi.c index df939b54b09f..771284473a97 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -961,32 +961,100 @@ void crypto_inc(u8 *a, unsigned int size) __be32 *b = (__be32 *)(a + size); u32 c; - for (; size >= 4; size -= 4) { - c = be32_to_cpu(*--b) + 1; - *b = cpu_to_be32(c); - if (c) - return; - } + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) || + !((unsigned long)b & (__alignof__(*b) - 1))) + for (; size >= 4; size -= 4) { + c = be32_to_cpu(*--b) + 1; + *b = cpu_to_be32(c); + if (c) + return; + } crypto_inc_byte(a, size); } EXPORT_SYMBOL_GPL(crypto_inc); -static inline void crypto_xor_byte(u8 *a, const u8 *b, unsigned int size) +void crypto_xor(u8 *dst, const u8 *src, unsigned int len) { - for (; size; size--) - *a++ ^= *b++; -} + const int size = sizeof(unsigned long); + const int mask = size - 1; + int misalign = ((unsigned long)dst ^ (unsigned long)src) & mask; + int startalign = ((unsigned long)dst | (unsigned long)src) & mask; + + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) + misalign = startalign = 0; + + while (len > 0) { + /* + * Process as much data as we can using 4 or 8 byte strides + * (depending on the size of unsigned long) if + * a) we don't care about alignment, or + * b) we do care about alignment, but dst and src are both + * suitably aligned + */ + if (startalign == 0) { + unsigned long *a = (unsigned long *)dst; + const unsigned long *b = (const unsigned long *)src; + + dst += len & ~mask; + src += len & ~mask; + + for (; len >= size; len -= size) + *a++ ^= *b++; + } -void crypto_xor(u8 *dst, const u8 *src, unsigned int size) -{ - u32 *a = (u32 *)dst; - u32 *b = (u32 *)src; + if (IS_ENABLED(CONFIG_64BIT)) { + do { + u32 *a = (u32 *)dst; + const u32 *b = (u32 *)src; + + if (len < sizeof(u32) || + (startalign & (sizeof(u32) - 1)) != 0) + break; + + if (len >= size && misalign != sizeof(u32) && + (startalign & sizeof(u32)) == 0) + break; + + *a ^= *b; + dst += sizeof(u32); + src += sizeof(u32); + len -= sizeof(u32); + startalign &= ~sizeof(u32); + } while (misalign == sizeof(u32)); + } - for (; size >= 4; size -= 4) - *a++ ^= *b++; + do { + u16 *a = (u16 *)dst; + const u16 *b = (u16 *)src; + + if (len < sizeof(u16) || + (startalign & (sizeof(u16) - 1)) != 0) + break; - crypto_xor_byte((u8 *)a, (u8 *)b, size); + if (len >= size && (startalign & sizeof(u16)) == 0 && + (misalign % sizeof(u32)) != sizeof(u16)) + break; + + *a ^= *b; + dst += sizeof(u16); + src += sizeof(u16); + len -= sizeof(u16); + startalign &= ~sizeof(u16); + } while ((misalign % sizeof(u32)) == sizeof(u16)); + + do { + if (len < sizeof(u8)) + break; + + if (len >= size && !(startalign & 1) && !(misalign & 1)) + break; + + *dst++ ^= *src++; + len -= sizeof(u8); + startalign &= ~sizeof(u8); + } while (misalign & 1); + } } EXPORT_SYMBOL_GPL(crypto_xor); diff --git a/crypto/cbc.c b/crypto/cbc.c index 68f751a41a84..bc160a3186dc 100644 --- a/crypto/cbc.c +++ b/crypto/cbc.c @@ -145,9 +145,6 @@ static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb) inst->alg.base.cra_blocksize = alg->cra_blocksize; inst->alg.base.cra_alignmask = alg->cra_alignmask; - /* We access the data as u32s when xoring. */ - inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; - inst->alg.ivsize = alg->cra_blocksize; inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize; inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize; diff --git a/crypto/cmac.c b/crypto/cmac.c index 04080dca8f0c..16301f52858c 100644 --- a/crypto/cmac.c +++ b/crypto/cmac.c @@ -260,8 +260,7 @@ static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb) if (err) goto out_free_inst; - /* We access the data as u32s when xoring. */ - alignmask = alg->cra_alignmask | (__alignof__(u32) - 1); + alignmask = alg->cra_alignmask; inst->alg.base.cra_alignmask = alignmask; inst->alg.base.cra_priority = alg->cra_priority; inst->alg.base.cra_blocksize = alg->cra_blocksize; diff --git a/crypto/ctr.c b/crypto/ctr.c index a9a7a44f2783..a4f4a8983169 100644 --- a/crypto/ctr.c +++ b/crypto/ctr.c @@ -209,7 +209,7 @@ static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb) inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; inst->alg.cra_priority = alg->cra_priority; inst->alg.cra_blocksize = 1; - inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1); + inst->alg.cra_alignmask = alg->cra_alignmask; inst->alg.cra_type = &crypto_blkcipher_type; inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; diff --git a/crypto/cts.c b/crypto/cts.c index a1335d6c35fb..243f591dc409 100644 --- a/crypto/cts.c +++ b/crypto/cts.c @@ -374,9 +374,6 @@ static int crypto_cts_create(struct crypto_template *tmpl, struct rtattr **tb) inst->alg.base.cra_blocksize = alg->base.cra_blocksize; inst->alg.base.cra_alignmask = alg->base.cra_alignmask; - /* We access the data as u32s when xoring. */ - inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; - inst->alg.ivsize = alg->base.cra_blocksize; inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg); diff --git a/crypto/pcbc.c b/crypto/pcbc.c index 11d248673ad4..29dd2b4a3b85 100644 --- a/crypto/pcbc.c +++ b/crypto/pcbc.c @@ -260,9 +260,6 @@ static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) inst->alg.base.cra_blocksize = alg->cra_blocksize; inst->alg.base.cra_alignmask = alg->cra_alignmask; - /* We access the data as u32s when xoring. */ - inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; - inst->alg.ivsize = alg->cra_blocksize; inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize; inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize; diff --git a/crypto/seqiv.c b/crypto/seqiv.c index c7049231861f..570b7d1aa0ca 100644 --- a/crypto/seqiv.c +++ b/crypto/seqiv.c @@ -153,8 +153,6 @@ static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb) if (IS_ERR(inst)) return PTR_ERR(inst); - inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; - spawn = aead_instance_ctx(inst); alg = crypto_spawn_aead_alg(spawn); -- 2.7.4