/* $OpenBSD: crypto_cpu_caps.c,v 1.2 2024/11/12 13:52:31 jsing Exp $ */
/*
 * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/sysctl.h>

#include <machine/cpu.h>

#include <stddef.h>
#include <stdio.h>

#include "crypto_arch.h"

/* Machine dependent CPU capabilities. */
uint64_t crypto_cpu_caps_aarch64;

static inline uint64_t
extract_bits(uint64_t val, int start, int end)
{
        return (val >> end) & (1ULL << (1 + start - end)) - 1;
}

static uint64_t
parse_isar0(uint64_t isar0)
{
        uint64_t caps = 0;
        uint64_t feature;

        /* AES - bits [7:4] */
        feature = extract_bits(isar0, 7, 4);
        if (feature >= 1)
                caps |= CRYPTO_CPU_CAPS_AARCH64_AES;
        if (feature >= 2)
                caps |= CRYPTO_CPU_CAPS_AARCH64_PMULL;

        /* SHA1 - bits [11:8] */
        feature = extract_bits(isar0, 11, 8);
        if (feature >= 1)
                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA1;

        /* SHA2 - bits [15:12] */
        feature = extract_bits(isar0, 15, 12);
        if (feature >= 1)
                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA2;
        if (feature >= 2)
                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA512;

        /* SHA3 - bits [35:32] */
        feature = extract_bits(isar0, 35, 32);
        if (feature >= 1)
                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA3;

        return caps;
}

static int
read_isar0(uint64_t *isar0)
{
        uint64_t isar;
        int mib[2];
        size_t len;

        mib[0] = CTL_MACHDEP;
        mib[1] = CPU_ID_AA64ISAR0;
        len = sizeof(isar);
        if (sysctl(mib, 2, &isar, &len, NULL, 0) == -1)
                return 0;

        *isar0 = isar;

        return 1;
}

void
crypto_cpu_caps_init(void)
{
        uint64_t isar = 0;

        if (!read_isar0(&isar))
                return;

        crypto_cpu_caps_aarch64 = parse_isar0(isar);
}