/* SPDX-License-Identifier: GPL-2.0 */
/*
 * ChaCha and HChaCha functions (ARM optimized)
 *
 * Copyright (C) 2016-2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
 * Copyright (C) 2015 Martin Willi
 */

#include <crypto/internal/simd.h>
#include <linux/jump_label.h>
#include <linux/kernel.h>

#include <asm/cputype.h>
#include <asm/hwcap.h>
#include <asm/simd.h>

asmlinkage void chacha_block_xor_neon(const struct chacha_state *state,
                                      u8 *dst, const u8 *src, int nrounds);
asmlinkage void chacha_4block_xor_neon(const struct chacha_state *state,
                                       u8 *dst, const u8 *src,
                                       int nrounds, unsigned int nbytes);
asmlinkage void hchacha_block_arm(const struct chacha_state *state,
                                  u32 out[HCHACHA_OUT_WORDS], int nrounds);
asmlinkage void hchacha_block_neon(const struct chacha_state *state,
                                   u32 out[HCHACHA_OUT_WORDS], int nrounds);

asmlinkage void chacha_doarm(u8 *dst, const u8 *src, unsigned int bytes,
                             const struct chacha_state *state, int nrounds);

static __ro_after_init DEFINE_STATIC_KEY_FALSE(use_neon);

static inline bool neon_usable(void)
{
        return static_branch_likely(&use_neon) && crypto_simd_usable();
}

static void chacha_doneon(struct chacha_state *state, u8 *dst, const u8 *src,
                          unsigned int bytes, int nrounds)
{
        u8 buf[CHACHA_BLOCK_SIZE];

        while (bytes > CHACHA_BLOCK_SIZE) {
                unsigned int l = min(bytes, CHACHA_BLOCK_SIZE * 4U);

                chacha_4block_xor_neon(state, dst, src, nrounds, l);
                bytes -= l;
                src += l;
                dst += l;
                state->x[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);
        }
        if (bytes) {
                const u8 *s = src;
                u8 *d = dst;

                if (bytes != CHACHA_BLOCK_SIZE)
                        s = d = memcpy(buf, src, bytes);
                chacha_block_xor_neon(state, d, s, nrounds);
                if (d != dst)
                        memcpy(dst, buf, bytes);
                state->x[12]++;
        }
}

static void hchacha_block_arch(const struct chacha_state *state,
                               u32 out[HCHACHA_OUT_WORDS], int nrounds)
{
        if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon_usable()) {
                hchacha_block_arm(state, out, nrounds);
        } else {
                scoped_ksimd()
                        hchacha_block_neon(state, out, nrounds);
        }
}

static void chacha_crypt_arch(struct chacha_state *state, u8 *dst,
                              const u8 *src, unsigned int bytes, int nrounds)
{
        if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon_usable() ||
            bytes <= CHACHA_BLOCK_SIZE) {
                chacha_doarm(dst, src, bytes, state, nrounds);
                state->x[12] += DIV_ROUND_UP(bytes, CHACHA_BLOCK_SIZE);
                return;
        }

        do {
                unsigned int todo = min_t(unsigned int, bytes, SZ_4K);

                scoped_ksimd()
                        chacha_doneon(state, dst, src, todo, nrounds);

                bytes -= todo;
                src += todo;
                dst += todo;
        } while (bytes);
}

#define chacha_mod_init_arch chacha_mod_init_arch
static void chacha_mod_init_arch(void)
{
        if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && (elf_hwcap & HWCAP_NEON)) {
                switch (read_cpuid_part()) {
                case ARM_CPU_PART_CORTEX_A7:
                case ARM_CPU_PART_CORTEX_A5:
                        /*
                         * The Cortex-A7 and Cortex-A5 do not perform well with
                         * the NEON implementation but do incredibly with the
                         * scalar one and use less power.
                         */
                        break;
                default:
                        static_branch_enable(&use_neon);
                }
        }
}