arch/x86/crypto/poly1305_glue.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0 OR MIT
 /*
  * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  */

 #include <crypto/algapi.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/poly1305.h>
 #include <crypto/internal/simd.h>
 #include <linux/crypto.h>
 #include <linux/jump_label.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/sizes.h>
 #include <asm/intel-family.h>
 #include <asm/simd.h>

 asmlinkage void poly1305_init_x86_64(void *ctx,
 				     const u8 key[POLY1305_KEY_SIZE]);
 asmlinkage void poly1305_blocks_x86_64(void *ctx, const u8 *inp,
 				       const size_t len, const u32 padbit);
 asmlinkage void poly1305_emit_x86_64(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
 				     const u32 nonce[4]);
 asmlinkage void poly1305_emit_avx(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
 				  const u32 nonce[4]);
 asmlinkage void poly1305_blocks_avx(void *ctx, const u8 *inp, const size_t len,
 				    const u32 padbit);
 asmlinkage void poly1305_blocks_avx2(void *ctx, const u8 *inp, const size_t len,
 				     const u32 padbit);
 asmlinkage void poly1305_blocks_avx512(void *ctx, const u8 *inp,
 				       const size_t len, const u32 padbit);

 static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx);
 static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx2);
 static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx512);

 struct poly1305_arch_internal {
 	union {
 		struct {
 			u32 h[5];
 			u32 is_base2_26;
 		};
 		u64 hs[3];
 	};
 	u64 r[2];
 	u64 pad;
 	struct { u32 r2, r1, r4, r3; } rn[9];
 };

 /* The AVX code uses base 2^26, while the scalar code uses base 2^64. If we hit
  * the unfortunate situation of using AVX and then having to go back to scalar
  * -- because the user is silly and has called the update function from two
  * separate contexts -- then we need to convert back to the original base before
  * proceeding. It is possible to reason that the initial reduction below is
  * sufficient given the implementation invariants. However, for an avoidance of
  * doubt and because this is not performance critical, we do the full reduction
  * anyway. Z3 proof of below function: https://xn--4db.cc/ltPtHCKN/py
  */
 static void convert_to_base2_64(void *ctx)
 {
 	struct poly1305_arch_internal *state = ctx;
 	u32 cy;

 	if (!state->is_base2_26)
 		return;

 	cy = state->h[0] >> 26; state->h[0] &= 0x3ffffff; state->h[1] += cy;
 	cy = state->h[1] >> 26; state->h[1] &= 0x3ffffff; state->h[2] += cy;
 	cy = state->h[2] >> 26; state->h[2] &= 0x3ffffff; state->h[3] += cy;
 	cy = state->h[3] >> 26; state->h[3] &= 0x3ffffff; state->h[4] += cy;
 	state->hs[0] = ((u64)state->h[2] << 52) | ((u64)state->h[1] << 26) | state->h[0];
 	state->hs[1] = ((u64)state->h[4] << 40) | ((u64)state->h[3] << 14) | (state->h[2] >> 12);
 	state->hs[2] = state->h[4] >> 24;
 #define ULT(a, b) ((a ^ ((a ^ b) | ((a - b) ^ b))) >> (sizeof(a) * 8 - 1))
 	cy = (state->hs[2] >> 2) + (state->hs[2] & ~3ULL);
 	state->hs[2] &= 3;
 	state->hs[0] += cy;
 	state->hs[1] += (cy = ULT(state->hs[0], cy));
 	state->hs[2] += ULT(state->hs[1], cy);
 #undef ULT
 	state->is_base2_26 = 0;
 }

 static void poly1305_simd_init(void *ctx, const u8 key[POLY1305_KEY_SIZE])
 {
 	poly1305_init_x86_64(ctx, key);
 }

 static void poly1305_simd_blocks(void *ctx, const u8 *inp, size_t len,
 				 const u32 padbit)
 {
 	struct poly1305_arch_internal *state = ctx;

 	/* SIMD disables preemption, so relax after processing each page. */
 	BUILD_BUG_ON(SZ_4K < POLY1305_BLOCK_SIZE ||
 		     SZ_4K % POLY1305_BLOCK_SIZE);

 	if (!static_branch_likely(&poly1305_use_avx) ||
 	    (len < (POLY1305_BLOCK_SIZE * 18) && !state->is_base2_26) ||
 	    !crypto_simd_usable()) {
 		convert_to_base2_64(ctx);
 		poly1305_blocks_x86_64(ctx, inp, len, padbit);
 		return;
 	}

 	do {
 		const size_t bytes = min_t(size_t, len, SZ_4K);

 		kernel_fpu_begin();
 		if (IS_ENABLED(CONFIG_AS_AVX512) && static_branch_likely(&poly1305_use_avx512))
 			poly1305_blocks_avx512(ctx, inp, bytes, padbit);
 		else if (static_branch_likely(&poly1305_use_avx2))
 			poly1305_blocks_avx2(ctx, inp, bytes, padbit);
 		else
 			poly1305_blocks_avx(ctx, inp, bytes, padbit);
 		kernel_fpu_end();

 		len -= bytes;
 		inp += bytes;
 	} while (len);
 }

 static void poly1305_simd_emit(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
 			       const u32 nonce[4])
 {
 	if (!static_branch_likely(&poly1305_use_avx))
 		poly1305_emit_x86_64(ctx, mac, nonce);
 	else
 		poly1305_emit_avx(ctx, mac, nonce);
 }

 void poly1305_init_arch(struct poly1305_desc_ctx *dctx, const u8 *key)
 {
 	poly1305_simd_init(&dctx->h, key);
 	dctx->s[0] = get_unaligned_le32(&key[16]);
 	dctx->s[1] = get_unaligned_le32(&key[20]);
 	dctx->s[2] = get_unaligned_le32(&key[24]);
 	dctx->s[3] = get_unaligned_le32(&key[28]);
 	dctx->buflen = 0;
 	dctx->sset = true;
 }
 EXPORT_SYMBOL(poly1305_init_arch);

 static unsigned int crypto_poly1305_setdctxkey(struct poly1305_desc_ctx *dctx,
 					       const u8 *inp, unsigned int len)
 {
 	unsigned int acc = 0;
 	if (unlikely(!dctx->sset)) {
 		if (!dctx->rset && len >= POLY1305_BLOCK_SIZE) {
 			poly1305_simd_init(&dctx->h, inp);
 			inp += POLY1305_BLOCK_SIZE;
 			len -= POLY1305_BLOCK_SIZE;
 			acc += POLY1305_BLOCK_SIZE;
 			dctx->rset = 1;
 		}
 		if (len >= POLY1305_BLOCK_SIZE) {
 			dctx->s[0] = get_unaligned_le32(&inp[0]);
 			dctx->s[1] = get_unaligned_le32(&inp[4]);
 			dctx->s[2] = get_unaligned_le32(&inp[8]);
 			dctx->s[3] = get_unaligned_le32(&inp[12]);
 			dctx->sset = true;
 		}
 	}
 	return acc;
 }

 void poly1305_update_arch(struct poly1305_desc_ctx *dctx, const u8 *src,
 			  unsigned int srclen)
 {
 	unsigned int bytes, used;

 	if (unlikely(dctx->buflen)) {
 		bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
 		memcpy(dctx->buf + dctx->buflen, src, bytes);
 		src += bytes;
 		srclen -= bytes;
 		dctx->buflen += bytes;

 		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
 			if (likely(!crypto_poly1305_setdctxkey(dctx, dctx->buf, POLY1305_BLOCK_SIZE)))
 				poly1305_simd_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 1);
 			dctx->buflen = 0;
 		}
 	}

 	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
 		bytes = round_down(srclen, POLY1305_BLOCK_SIZE);
 		srclen -= bytes;
 		used = crypto_poly1305_setdctxkey(dctx, src, bytes);
 		if (likely(bytes - used))
 			poly1305_simd_blocks(&dctx->h, src + used, bytes - used, 1);
 		src += bytes;
 	}

 	if (unlikely(srclen)) {
 		dctx->buflen = srclen;
 		memcpy(dctx->buf, src, srclen);
 	}
 }
 EXPORT_SYMBOL(poly1305_update_arch);

 void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
 {
 	if (unlikely(dctx->buflen)) {
 		dctx->buf[dctx->buflen++] = 1;
 		memset(dctx->buf + dctx->buflen, 0,
 		       POLY1305_BLOCK_SIZE - dctx->buflen);
 		poly1305_simd_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
 	}

 	poly1305_simd_emit(&dctx->h, dst, dctx->s);
 	*dctx = (struct poly1305_desc_ctx){};
 }
 EXPORT_SYMBOL(poly1305_final_arch);

 static int crypto_poly1305_init(struct shash_desc *desc)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

 	*dctx = (struct poly1305_desc_ctx){};
 	return 0;
 }

 static int crypto_poly1305_update(struct shash_desc *desc,
 				  const u8 *src, unsigned int srclen)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

 	poly1305_update_arch(dctx, src, srclen);
 	return 0;
 }

 static int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

 	if (unlikely(!dctx->sset))
 		return -ENOKEY;

 	poly1305_final_arch(dctx, dst);
 	return 0;
 }

 static struct shash_alg alg = {
 	.digestsize	= POLY1305_DIGEST_SIZE,
 	.init		= crypto_poly1305_init,
 	.update		= crypto_poly1305_update,
 	.final		= crypto_poly1305_final,
 	.descsize	= sizeof(struct poly1305_desc_ctx),
 	.base		= {
 		.cra_name		= "poly1305",
 		.cra_driver_name	= "poly1305-simd",
 		.cra_priority		= 300,
 		.cra_blocksize		= POLY1305_BLOCK_SIZE,
 		.cra_module		= THIS_MODULE,
 	},
 };

 static int __init poly1305_simd_mod_init(void)
 {
 	if (boot_cpu_has(X86_FEATURE_AVX) &&
 	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
 		static_branch_enable(&poly1305_use_avx);
 	if (boot_cpu_has(X86_FEATURE_AVX) && boot_cpu_has(X86_FEATURE_AVX2) &&
 	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
 		static_branch_enable(&poly1305_use_avx2);
 	if (IS_ENABLED(CONFIG_AS_AVX512) && boot_cpu_has(X86_FEATURE_AVX) &&
 	    boot_cpu_has(X86_FEATURE_AVX2) && boot_cpu_has(X86_FEATURE_AVX512F) &&
 	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM | XFEATURE_MASK_AVX512, NULL) &&
 	    /* Skylake downclocks unacceptably much when using zmm, but later generations are fast. */
 	    boot_cpu_data.x86_model != INTEL_FAM6_SKYLAKE_X)
 		static_branch_enable(&poly1305_use_avx512);
 	return IS_REACHABLE(CONFIG_CRYPTO_HASH) ? crypto_register_shash(&alg) : 0;
 }

 static void __exit poly1305_simd_mod_exit(void)
 {
 	if (IS_REACHABLE(CONFIG_CRYPTO_HASH))
 		crypto_unregister_shash(&alg);
 }

 module_init(poly1305_simd_mod_init);
 module_exit(poly1305_simd_mod_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
 MODULE_DESCRIPTION("Poly1305 authenticator");
 MODULE_ALIAS_CRYPTO("poly1305");
 MODULE_ALIAS_CRYPTO("poly1305-simd");
	// SPDX-License-Identifier: GPL-2.0 OR MIT
	/*
	* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
	*/

	#include <crypto/algapi.h>
	#include <crypto/internal/hash.h>
	#include <crypto/internal/poly1305.h>
	#include <crypto/internal/simd.h>
	#include <linux/crypto.h>
	#include <linux/jump_label.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/sizes.h>
	#include <asm/intel-family.h>
	#include <asm/simd.h>

	asmlinkage void poly1305_init_x86_64(void *ctx,
	const u8 key[POLY1305_KEY_SIZE]);
	asmlinkage void poly1305_blocks_x86_64(void ctx, const u8 inp,
	const size_t len, const u32 padbit);
	asmlinkage void poly1305_emit_x86_64(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
	const u32 nonce[4]);
	asmlinkage void poly1305_emit_avx(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
	const u32 nonce[4]);
	asmlinkage void poly1305_blocks_avx(void ctx, const u8 inp, const size_t len,
	const u32 padbit);
	asmlinkage void poly1305_blocks_avx2(void ctx, const u8 inp, const size_t len,
	const u32 padbit);
	asmlinkage void poly1305_blocks_avx512(void ctx, const u8 inp,
	const size_t len, const u32 padbit);

	static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx);
	static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx2);
	static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx512);

	struct poly1305_arch_internal {
	union {
	struct {
	u32 h[5];
	u32 is_base2_26;
	};
	u64 hs[3];
	};
	u64 r[2];
	u64 pad;
	struct { u32 r2, r1, r4, r3; } rn[9];
	};

	/* The AVX code uses base 2^26, while the scalar code uses base 2^64. If we hit
	* the unfortunate situation of using AVX and then having to go back to scalar
	* -- because the user is silly and has called the update function from two
	* separate contexts -- then we need to convert back to the original base before
	* proceeding. It is possible to reason that the initial reduction below is
	* sufficient given the implementation invariants. However, for an avoidance of
	* doubt and because this is not performance critical, we do the full reduction
	* anyway. Z3 proof of below function: https://xn--4db.cc/ltPtHCKN/py
	*/
	static void convert_to_base2_64(void *ctx)
	{
	struct poly1305_arch_internal *state = ctx;
	u32 cy;

	if (!state->is_base2_26)
	return;

	cy = state->h[0] >> 26; state->h[0] &= 0x3ffffff; state->h[1] += cy;
	cy = state->h[1] >> 26; state->h[1] &= 0x3ffffff; state->h[2] += cy;
	cy = state->h[2] >> 26; state->h[2] &= 0x3ffffff; state->h[3] += cy;
	cy = state->h[3] >> 26; state->h[3] &= 0x3ffffff; state->h[4] += cy;
	state->hs[0] = ((u64)state->h[2] << 52) \| ((u64)state->h[1] << 26) \| state->h[0];
	state->hs[1] = ((u64)state->h[4] << 40) \| ((u64)state->h[3] << 14) \| (state->h[2] >> 12);
	state->hs[2] = state->h[4] >> 24;
	#define ULT(a, b) ((a ^ ((a ^ b) \| ((a - b) ^ b))) >> (sizeof(a) * 8 - 1))
	cy = (state->hs[2] >> 2) + (state->hs[2] & ~3ULL);
	state->hs[2] &= 3;
	state->hs[0] += cy;
	state->hs[1] += (cy = ULT(state->hs[0], cy));
	state->hs[2] += ULT(state->hs[1], cy);
	#undef ULT
	state->is_base2_26 = 0;
	}

	static void poly1305_simd_init(void *ctx, const u8 key[POLY1305_KEY_SIZE])
	{
	poly1305_init_x86_64(ctx, key);
	}

	static void poly1305_simd_blocks(void ctx, const u8 inp, size_t len,
	const u32 padbit)
	{
	struct poly1305_arch_internal *state = ctx;

	/* SIMD disables preemption, so relax after processing each page. */
	BUILD_BUG_ON(SZ_4K < POLY1305_BLOCK_SIZE \|\|
	SZ_4K % POLY1305_BLOCK_SIZE);

	if (!static_branch_likely(&poly1305_use_avx) \|\|
	(len < (POLY1305_BLOCK_SIZE * 18) && !state->is_base2_26) \|\|
	!crypto_simd_usable()) {
	convert_to_base2_64(ctx);
	poly1305_blocks_x86_64(ctx, inp, len, padbit);
	return;
	}

	do {
	const size_t bytes = min_t(size_t, len, SZ_4K);

	kernel_fpu_begin();
	if (IS_ENABLED(CONFIG_AS_AVX512) && static_branch_likely(&poly1305_use_avx512))
	poly1305_blocks_avx512(ctx, inp, bytes, padbit);
	else if (static_branch_likely(&poly1305_use_avx2))
	poly1305_blocks_avx2(ctx, inp, bytes, padbit);
	else
	poly1305_blocks_avx(ctx, inp, bytes, padbit);
	kernel_fpu_end();

	len -= bytes;
	inp += bytes;
	} while (len);
	}

	static void poly1305_simd_emit(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
	const u32 nonce[4])
	{
	if (!static_branch_likely(&poly1305_use_avx))
	poly1305_emit_x86_64(ctx, mac, nonce);
	else
	poly1305_emit_avx(ctx, mac, nonce);
	}

	void poly1305_init_arch(struct poly1305_desc_ctx dctx, const u8 key)
	{
	poly1305_simd_init(&dctx->h, key);
	dctx->s[0] = get_unaligned_le32(&key[16]);
	dctx->s[1] = get_unaligned_le32(&key[20]);
	dctx->s[2] = get_unaligned_le32(&key[24]);
	dctx->s[3] = get_unaligned_le32(&key[28]);
	dctx->buflen = 0;
	dctx->sset = true;
	}
	EXPORT_SYMBOL(poly1305_init_arch);

	static unsigned int crypto_poly1305_setdctxkey(struct poly1305_desc_ctx *dctx,
	const u8 *inp, unsigned int len)
	{
	unsigned int acc = 0;
	if (unlikely(!dctx->sset)) {
	if (!dctx->rset && len >= POLY1305_BLOCK_SIZE) {
	poly1305_simd_init(&dctx->h, inp);
	inp += POLY1305_BLOCK_SIZE;
	len -= POLY1305_BLOCK_SIZE;
	acc += POLY1305_BLOCK_SIZE;
	dctx->rset = 1;
	}
	if (len >= POLY1305_BLOCK_SIZE) {
	dctx->s[0] = get_unaligned_le32(&inp[0]);
	dctx->s[1] = get_unaligned_le32(&inp[4]);
	dctx->s[2] = get_unaligned_le32(&inp[8]);
	dctx->s[3] = get_unaligned_le32(&inp[12]);
	dctx->sset = true;
	}
	}
	return acc;
	}

	void poly1305_update_arch(struct poly1305_desc_ctx dctx, const u8 src,
	unsigned int srclen)
	{
	unsigned int bytes, used;

	if (unlikely(dctx->buflen)) {
	bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
	memcpy(dctx->buf + dctx->buflen, src, bytes);
	src += bytes;
	srclen -= bytes;
	dctx->buflen += bytes;

	if (dctx->buflen == POLY1305_BLOCK_SIZE) {
	if (likely(!crypto_poly1305_setdctxkey(dctx, dctx->buf, POLY1305_BLOCK_SIZE)))
	poly1305_simd_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 1);
	dctx->buflen = 0;
	}
	}

	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
	bytes = round_down(srclen, POLY1305_BLOCK_SIZE);
	srclen -= bytes;
	used = crypto_poly1305_setdctxkey(dctx, src, bytes);
	if (likely(bytes - used))
	poly1305_simd_blocks(&dctx->h, src + used, bytes - used, 1);
	src += bytes;
	}

	if (unlikely(srclen)) {
	dctx->buflen = srclen;
	memcpy(dctx->buf, src, srclen);
	}
	}
	EXPORT_SYMBOL(poly1305_update_arch);

	void poly1305_final_arch(struct poly1305_desc_ctx dctx, u8 dst)
	{
	if (unlikely(dctx->buflen)) {
	dctx->buf[dctx->buflen++] = 1;
	memset(dctx->buf + dctx->buflen, 0,
	POLY1305_BLOCK_SIZE - dctx->buflen);
	poly1305_simd_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
	}

	poly1305_simd_emit(&dctx->h, dst, dctx->s);
	*dctx = (struct poly1305_desc_ctx){};
	}
	EXPORT_SYMBOL(poly1305_final_arch);

	static int crypto_poly1305_init(struct shash_desc *desc)
	{
	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

	*dctx = (struct poly1305_desc_ctx){};
	return 0;
	}

	static int crypto_poly1305_update(struct shash_desc *desc,
	const u8 *src, unsigned int srclen)
	{
	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

	poly1305_update_arch(dctx, src, srclen);
	return 0;
	}

	static int crypto_poly1305_final(struct shash_desc desc, u8 dst)
	{
	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

	if (unlikely(!dctx->sset))
	return -ENOKEY;

	poly1305_final_arch(dctx, dst);
	return 0;
	}

	static struct shash_alg alg = {
	.digestsize = POLY1305_DIGEST_SIZE,
	.init = crypto_poly1305_init,
	.update = crypto_poly1305_update,
	.final = crypto_poly1305_final,
	.descsize = sizeof(struct poly1305_desc_ctx),
	.base = {
	.cra_name = "poly1305",
	.cra_driver_name = "poly1305-simd",
	.cra_priority = 300,
	.cra_blocksize = POLY1305_BLOCK_SIZE,
	.cra_module = THIS_MODULE,
	},
	};

	static int __init poly1305_simd_mod_init(void)
	{
	if (boot_cpu_has(X86_FEATURE_AVX) &&
	cpu_has_xfeatures(XFEATURE_MASK_SSE \| XFEATURE_MASK_YMM, NULL))
	static_branch_enable(&poly1305_use_avx);
	if (boot_cpu_has(X86_FEATURE_AVX) && boot_cpu_has(X86_FEATURE_AVX2) &&
	cpu_has_xfeatures(XFEATURE_MASK_SSE \| XFEATURE_MASK_YMM, NULL))
	static_branch_enable(&poly1305_use_avx2);
	if (IS_ENABLED(CONFIG_AS_AVX512) && boot_cpu_has(X86_FEATURE_AVX) &&
	boot_cpu_has(X86_FEATURE_AVX2) && boot_cpu_has(X86_FEATURE_AVX512F) &&
	cpu_has_xfeatures(XFEATURE_MASK_SSE \| XFEATURE_MASK_YMM \| XFEATURE_MASK_AVX512, NULL) &&
	/* Skylake downclocks unacceptably much when using zmm, but later generations are fast. */
	boot_cpu_data.x86_model != INTEL_FAM6_SKYLAKE_X)
	static_branch_enable(&poly1305_use_avx512);
	return IS_REACHABLE(CONFIG_CRYPTO_HASH) ? crypto_register_shash(&alg) : 0;
	}

	static void __exit poly1305_simd_mod_exit(void)
	{
	if (IS_REACHABLE(CONFIG_CRYPTO_HASH))
	crypto_unregister_shash(&alg);
	}

	module_init(poly1305_simd_mod_init);
	module_exit(poly1305_simd_mod_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
	MODULE_DESCRIPTION("Poly1305 authenticator");
	MODULE_ALIAS_CRYPTO("poly1305");
	MODULE_ALIAS_CRYPTO("poly1305-simd");