// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * SHA-256 optimized for x86_64
 *
 * Copyright 2025 Google LLC
 */
#include <asm/fpu/api.h>
#include <crypto/internal/sha2.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/static_call.h>

asmlinkage void sha256_transform_ssse3(u32 state[SHA256_STATE_WORDS],
				       const u8 *data, size_t nblocks);
asmlinkage void sha256_transform_avx(u32 state[SHA256_STATE_WORDS],
				     const u8 *data, size_t nblocks);
asmlinkage void sha256_transform_rorx(u32 state[SHA256_STATE_WORDS],
				      const u8 *data, size_t nblocks);
asmlinkage void sha256_ni_transform(u32 state[SHA256_STATE_WORDS],
				    const u8 *data, size_t nblocks);

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_sha256_x86);

DEFINE_STATIC_CALL(sha256_blocks_x86, sha256_transform_ssse3);

void sha256_blocks_simd(u32 state[SHA256_STATE_WORDS],
			const u8 *data, size_t nblocks)
{
	if (static_branch_likely(&have_sha256_x86)) {
		kernel_fpu_begin();
		static_call(sha256_blocks_x86)(state, data, nblocks);
		kernel_fpu_end();
	} else {
		sha256_blocks_generic(state, data, nblocks);
	}
}
EXPORT_SYMBOL_GPL(sha256_blocks_simd);

void sha256_blocks_arch(u32 state[SHA256_STATE_WORDS],
			const u8 *data, size_t nblocks)
{
	sha256_blocks_generic(state, data, nblocks);
}
EXPORT_SYMBOL_GPL(sha256_blocks_arch);

bool sha256_is_arch_optimized(void)
{
	return static_key_enabled(&have_sha256_x86);
}
EXPORT_SYMBOL_GPL(sha256_is_arch_optimized);

static int __init sha256_x86_mod_init(void)
{
	if (boot_cpu_has(X86_FEATURE_SHA_NI)) {
		static_call_update(sha256_blocks_x86, sha256_ni_transform);
	} else if (cpu_has_xfeatures(XFEATURE_MASK_SSE |
				     XFEATURE_MASK_YMM, NULL) &&
		   boot_cpu_has(X86_FEATURE_AVX)) {
		if (boot_cpu_has(X86_FEATURE_AVX2) &&
		    boot_cpu_has(X86_FEATURE_BMI2))
			static_call_update(sha256_blocks_x86,
					   sha256_transform_rorx);
		else
			static_call_update(sha256_blocks_x86,
					   sha256_transform_avx);
	} else if (!boot_cpu_has(X86_FEATURE_SSSE3)) {
		return 0;
	}
	static_branch_enable(&have_sha256_x86);
	return 0;
}
subsys_initcall(sha256_x86_mod_init);

static void __exit sha256_x86_mod_exit(void)
{
}
module_exit(sha256_x86_mod_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SHA-256 optimized for x86_64");