crypto: vmx - ghash: do nosimd fallback manually

VMX ghash was using a fallback that did not support interleaving simd
and nosimd operations, leading to failures in the extended test suite.

If I understood correctly, Eric's suggestion was to use the same
data format that the generic code uses, allowing us to call into it
with the same contexts. I wasn't able to get that to work - I think
there's a very different key structure and data layout being used.

So instead steal the arm64 approach and perform the fallback
operations directly if required.

Fixes: cc333cd68d ("crypto: vmx - Adding GHASH routines for VMX module")
Cc: stable@vger.kernel.org # v4.1+
Reported-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/vmx/ghash.c

@@ -1,22 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
 /**
  * GHASH routines supporting VMX instructions on the Power 8
  *
- * Copyright (C) 2015 International Business Machines Inc.
+ * Copyright (C) 2015, 2019 International Business Machines Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 only.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  *
  * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>
+ *
+ * Extended by Daniel Axtens <dja@axtens.net> to replace the fallback
+ * mechanism. The new approach is based on arm64 code, which is:
+ *   Copyright (C) 2014 - 2018 Linaro Ltd. <ard.biesheuvel@linaro.org>
  */
 
 #include <linux/types.h>
@@ -38,70 +30,25 @@ void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],
 		  const u8 *in, size_t len);
 
 struct p8_ghash_ctx {
+	/* key used by vector asm */
 	u128 htable[16];
-	struct crypto_shash *fallback;
+	/* key used by software fallback */
+	be128 key;
 };
 
 struct p8_ghash_desc_ctx {
 	u64 shash[2];
 	u8 buffer[GHASH_DIGEST_SIZE];
 	int bytes;
-	struct shash_desc fallback_desc;
 };
 
-static int p8_ghash_init_tfm(struct crypto_tfm *tfm)
-{
-	const char *alg = "ghash-generic";
-	struct crypto_shash *fallback;
-	struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);
-	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
-
-	fallback = crypto_alloc_shash(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
-	if (IS_ERR(fallback)) {
-		printk(KERN_ERR
-		       "Failed to allocate transformation for '%s': %ld\n",
-		       alg, PTR_ERR(fallback));
-		return PTR_ERR(fallback);
-	}
-
-	crypto_shash_set_flags(fallback,
-			       crypto_shash_get_flags((struct crypto_shash
-						       *) tfm));
-
-	/* Check if the descsize defined in the algorithm is still enough. */
-	if (shash_tfm->descsize < sizeof(struct p8_ghash_desc_ctx)
-	    + crypto_shash_descsize(fallback)) {
-		printk(KERN_ERR
-		       "Desc size of the fallback implementation (%s) does not match the expected value: %lu vs %u\n",
-		       alg,
-		       shash_tfm->descsize - sizeof(struct p8_ghash_desc_ctx),
-		       crypto_shash_descsize(fallback));
-		return -EINVAL;
-	}
-	ctx->fallback = fallback;
-
-	return 0;
-}
-
-static void p8_ghash_exit_tfm(struct crypto_tfm *tfm)
-{
-	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
-
-	if (ctx->fallback) {
-		crypto_free_shash(ctx->fallback);
-		ctx->fallback = NULL;
-	}
-}
-
 static int p8_ghash_init(struct shash_desc *desc)
 {
-	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
 	struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 
 	dctx->bytes = 0;
 	memset(dctx->shash, 0, GHASH_DIGEST_SIZE);
-	dctx->fallback_desc.tfm = ctx->fallback;
+	return 0;
-	return crypto_shash_init(&dctx->fallback_desc);
 }
 
 static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
@@ -119,7 +66,51 @@ static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
 	disable_kernel_vsx();
 	pagefault_enable();
 	preempt_enable();
-	return crypto_shash_setkey(ctx->fallback, key, keylen);
+
+	memcpy(&ctx->key, key, GHASH_BLOCK_SIZE);
+
+	return 0;
+}
+
+static inline void __ghash_block(struct p8_ghash_ctx *ctx,
+				 struct p8_ghash_desc_ctx *dctx)
+{
+	if (crypto_simd_usable()) {
+		preempt_disable();
+		pagefault_disable();
+		enable_kernel_vsx();
+		gcm_ghash_p8(dctx->shash, ctx->htable,
+				dctx->buffer, GHASH_DIGEST_SIZE);
+		disable_kernel_vsx();
+		pagefault_enable();
+		preempt_enable();
+	} else {
+		crypto_xor((u8 *)dctx->shash, dctx->buffer, GHASH_BLOCK_SIZE);
+		gf128mul_lle((be128 *)dctx->shash, &ctx->key);
+	}
+}
+
+static inline void __ghash_blocks(struct p8_ghash_ctx *ctx,
+				  struct p8_ghash_desc_ctx *dctx,
+				  const u8 *src, unsigned int srclen)
+{
+	if (crypto_simd_usable()) {
+		preempt_disable();
+		pagefault_disable();
+		enable_kernel_vsx();
+		gcm_ghash_p8(dctx->shash, ctx->htable,
+				src, srclen);
+		disable_kernel_vsx();
+		pagefault_enable();
+		preempt_enable();
+	} else {
+		while (srclen >= GHASH_BLOCK_SIZE) {
+			crypto_xor((u8 *)dctx->shash, src, GHASH_BLOCK_SIZE);
+			gf128mul_lle((be128 *)dctx->shash, &ctx->key);
+			srclen -= GHASH_BLOCK_SIZE;
+			src += GHASH_BLOCK_SIZE;
+		}
+	}
 }
 
 static int p8_ghash_update(struct shash_desc *desc,
@@ -129,10 +120,6 @@ static int p8_ghash_update(struct shash_desc *desc,
 	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
 	struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 
-	if (!crypto_simd_usable()) {
-		return crypto_shash_update(&dctx->fallback_desc, src,
-					   srclen);
-	} else {
 	if (dctx->bytes) {
 		if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {
 			memcpy(dctx->buffer + dctx->bytes, src,
@@ -142,27 +129,16 @@ static int p8_ghash_update(struct shash_desc *desc,
 		}
 		memcpy(dctx->buffer + dctx->bytes, src,
 			GHASH_DIGEST_SIZE - dctx->bytes);
-			preempt_disable();
+
-			pagefault_disable();
+		__ghash_block(ctx, dctx);
-			enable_kernel_vsx();
+
-			gcm_ghash_p8(dctx->shash, ctx->htable,
-				     dctx->buffer, GHASH_DIGEST_SIZE);
-			disable_kernel_vsx();
-			pagefault_enable();
-			preempt_enable();
 		src += GHASH_DIGEST_SIZE - dctx->bytes;
 		srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
 		dctx->bytes = 0;
 	}
 	len = srclen & ~(GHASH_DIGEST_SIZE - 1);
 	if (len) {
-			preempt_disable();
+		__ghash_blocks(ctx, dctx, src, len);
-			pagefault_disable();
-			enable_kernel_vsx();
-			gcm_ghash_p8(dctx->shash, ctx->htable, src, len);
-			disable_kernel_vsx();
-			pagefault_enable();
-			preempt_enable();
 		src += len;
 		srclen -= len;
 	}
@@ -171,7 +147,6 @@ static int p8_ghash_update(struct shash_desc *desc,
 		dctx->bytes = srclen;
 	}
 	return 0;
-	}
 }
 
 static int p8_ghash_final(struct shash_desc *desc, u8 *out)
@@ -180,25 +155,14 @@ static int p8_ghash_final(struct shash_desc *desc, u8 *out)
 	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
 	struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 
-	if (!crypto_simd_usable()) {
-		return crypto_shash_final(&dctx->fallback_desc, out);
-	} else {
 	if (dctx->bytes) {
 		for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
 			dctx->buffer[i] = 0;
-			preempt_disable();
+		__ghash_block(ctx, dctx);
-			pagefault_disable();
-			enable_kernel_vsx();
-			gcm_ghash_p8(dctx->shash, ctx->htable,
-				     dctx->buffer, GHASH_DIGEST_SIZE);
-			disable_kernel_vsx();
-			pagefault_enable();
-			preempt_enable();
 		dctx->bytes = 0;
 	}
 	memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
 	return 0;
-	}
 }
 
 struct shash_alg p8_ghash_alg = {
@@ -213,11 +177,8 @@ struct shash_alg p8_ghash_alg = {
 		 .cra_name = "ghash",
 		 .cra_driver_name = "p8_ghash",
 		 .cra_priority = 1000,
-		 .cra_flags = CRYPTO_ALG_NEED_FALLBACK,
 		 .cra_blocksize = GHASH_BLOCK_SIZE,
 		 .cra_ctxsize = sizeof(struct p8_ghash_ctx),
 		 .cra_module = THIS_MODULE,
-		 .cra_init = p8_ghash_init_tfm,
-		 .cra_exit = p8_ghash_exit_tfm,
 	},
 };