crypto: vmx - Adding GHASH routines for VMX module

This patch adds GHASH routines to VMX module in order to
make use of VMX cryptographic acceleration instructions
on Power 8 CPU.
Signed-off-by: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/vmx/ghash.c

+/**
+ * GHASH routines supporting VMX instructions on the Power 8
+ *
+ * Copyright (C) 2015 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>
+ */
+
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/crypto.h>
+#include <linux/delay.h>
+#include <linux/hardirq.h>
+#include <asm/switch_to.h>
+#include <crypto/aes.h>
+#include <crypto/scatterwalk.h>
+#include <crypto/internal/hash.h>
+#include <crypto/b128ops.h>
+
+#define IN_INTERRUPT in_interrupt()
+
+#define GHASH_BLOCK_SIZE (16)
+#define GHASH_DIGEST_SIZE (16)
+#define GHASH_KEY_LEN (16)
+
+void gcm_init_p8(u128 htable[16], const u64 Xi[2]);
+void gcm_gmult_p8(u64 Xi[2], const u128 htable[16]);
+void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],
+        const u8 *in,size_t len);
+
+struct p8_ghash_ctx {
+    u128 htable[16];
+    struct crypto_shash *fallback;
+};
+
+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;
+    struct crypto_shash *fallback;
+    struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);
+    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
+
+    if (!(alg = crypto_tfm_alg_name(tfm))) {
+        printk(KERN_ERR "Failed to get algorithm name.\n");
+        return -ENOENT;
+    }
+
+    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);
+    }
+    printk(KERN_INFO "Using '%s' as fallback implementation.\n",
+            crypto_tfm_alg_driver_name(crypto_shash_tfm(fallback)));
+
+    crypto_shash_set_flags(fallback,
+            crypto_shash_get_flags((struct crypto_shash *) tfm));
+    ctx->fallback = fallback;
+
+    shash_tfm->descsize = sizeof(struct p8_ghash_desc_ctx)
+        + crypto_shash_descsize(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;
+    dctx->fallback_desc.flags = desc->flags;
+    return crypto_shash_init(&dctx->fallback_desc);
+}
+
+static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
+    unsigned int keylen)
+{
+    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(tfm));
+
+    if (keylen != GHASH_KEY_LEN)
+        return -EINVAL;
+
+    pagefault_disable();
+    enable_kernel_altivec();
+    enable_kernel_fp();
+    gcm_init_p8(ctx->htable, (const u64 *) key);
+    pagefault_enable();
+    return crypto_shash_setkey(ctx->fallback, key, keylen);
+}
+
+static int p8_ghash_update(struct shash_desc *desc,
+        const u8 *src, unsigned int srclen)
+{
+    unsigned int len;
+    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
+    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+
+    if (IN_INTERRUPT) {
+        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, srclen);
+                dctx->bytes += srclen;
+                return 0;
+            }
+            memcpy(dctx->buffer + dctx->bytes, src,
+                    GHASH_DIGEST_SIZE - dctx->bytes);
+            pagefault_disable();
+            enable_kernel_altivec();
+            enable_kernel_fp();
+            gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,
+                    GHASH_DIGEST_SIZE);
+            pagefault_enable();
+            src += GHASH_DIGEST_SIZE - dctx->bytes;
+            srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
+            dctx->bytes = 0;
+        }
+        len = srclen & ~(GHASH_DIGEST_SIZE - 1);
+        if (len) {
+            pagefault_disable();
+            enable_kernel_altivec();
+            enable_kernel_fp();
+            gcm_ghash_p8(dctx->shash, ctx->htable, src, len);
+            pagefault_enable();
+            src += len;
+            srclen -= len;
+        }
+        if (srclen) {
+            memcpy(dctx->buffer, src, srclen);
+            dctx->bytes = srclen;
+        }
+        return 0;
+    }
+}
+
+static int p8_ghash_final(struct shash_desc *desc, u8 *out)
+{
+    int i;
+    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
+    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+
+    if (IN_INTERRUPT) {
+        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;
+            pagefault_disable();
+            enable_kernel_altivec();
+            enable_kernel_fp();
+            gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,
+                    GHASH_DIGEST_SIZE);
+            pagefault_enable();
+            dctx->bytes = 0;
+        }
+        memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
+        return 0;
+    }
+}
+
+struct shash_alg p8_ghash_alg = {
+    .digestsize = GHASH_DIGEST_SIZE,
+    .init       = p8_ghash_init,
+    .update     = p8_ghash_update,
+    .final      = p8_ghash_final,
+    .setkey     = p8_ghash_setkey,
+    .descsize   = sizeof(struct p8_ghash_desc_ctx),
+    .base       = {
+        .cra_name = "ghash",
+        .cra_driver_name = "p8_ghash",
+        .cra_priority = 1000,
+        .cra_flags = CRYPTO_ALG_TYPE_SHASH | 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,
+    },
+};