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144 lines
3.4 KiB
144 lines
3.4 KiB
/*
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* Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <assert.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <arch_features.h>
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#include <lib/smccc.h>
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#include <services/trng_svc.h>
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#include <smccc_helpers.h>
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#include <plat/common/plat_trng.h>
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#include "trng_entropy_pool.h"
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static const uuid_t uuid_null;
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/* handle the RND call in SMC 32 bit mode */
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static uintptr_t trng_rnd32(uint32_t nbits, void *handle)
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{
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uint32_t mask = ~0U;
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uint64_t ent[2];
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if (nbits == 0U || nbits > 96U) {
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SMC_RET1(handle, TRNG_E_INVALID_PARAMS);
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}
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if (!trng_pack_entropy(nbits, &ent[0])) {
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SMC_RET1(handle, TRNG_E_NO_ENTROPY);
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}
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if ((nbits % 32U) != 0U) {
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mask >>= 32U - (nbits % 32U);
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}
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switch ((nbits - 1U) / 32U) {
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case 0:
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SMC_RET4(handle, TRNG_E_SUCCESS, 0, 0, ent[0] & mask);
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break; /* unreachable */
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case 1:
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SMC_RET4(handle, TRNG_E_SUCCESS, 0, (ent[0] >> 32) & mask,
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ent[0] & 0xFFFFFFFF);
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break; /* unreachable */
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case 2:
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SMC_RET4(handle, TRNG_E_SUCCESS, ent[1] & mask,
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(ent[0] >> 32) & 0xFFFFFFFF, ent[0] & 0xFFFFFFFF);
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break; /* unreachable */
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default:
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SMC_RET1(handle, TRNG_E_INVALID_PARAMS);
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break; /* unreachable */
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}
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}
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/* handle the RND call in SMC 64 bit mode */
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static uintptr_t trng_rnd64(uint32_t nbits, void *handle)
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{
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uint64_t mask = ~0ULL;
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uint64_t ent[3];
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if (nbits == 0U || nbits > 192U) {
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SMC_RET1(handle, TRNG_E_INVALID_PARAMS);
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}
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if (!trng_pack_entropy(nbits, &ent[0])) {
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SMC_RET1(handle, TRNG_E_NO_ENTROPY);
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}
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/* Mask off higher bits if only part of register requested */
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if ((nbits % 64U) != 0U) {
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mask >>= 64U - (nbits % 64U);
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}
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switch ((nbits - 1U) / 64U) {
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case 0:
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SMC_RET4(handle, TRNG_E_SUCCESS, 0, 0, ent[0] & mask);
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break; /* unreachable */
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case 1:
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SMC_RET4(handle, TRNG_E_SUCCESS, 0, ent[1] & mask, ent[0]);
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break; /* unreachable */
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case 2:
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SMC_RET4(handle, TRNG_E_SUCCESS, ent[2] & mask, ent[1], ent[0]);
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break; /* unreachable */
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default:
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SMC_RET1(handle, TRNG_E_INVALID_PARAMS);
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break; /* unreachable */
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}
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}
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void trng_setup(void)
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{
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trng_entropy_pool_setup();
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plat_entropy_setup();
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}
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/* Predicate indicating that a function id is part of TRNG */
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bool is_trng_fid(uint32_t smc_fid)
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{
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return ((smc_fid == ARM_TRNG_VERSION) ||
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(smc_fid == ARM_TRNG_FEATURES) ||
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(smc_fid == ARM_TRNG_GET_UUID) ||
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(smc_fid == ARM_TRNG_RND32) ||
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(smc_fid == ARM_TRNG_RND64));
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}
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uintptr_t trng_smc_handler(uint32_t smc_fid, u_register_t x1, u_register_t x2,
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u_register_t x3, u_register_t x4, void *cookie,
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void *handle, u_register_t flags)
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{
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if (!memcmp(&plat_trng_uuid, &uuid_null, sizeof(uuid_t))) {
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SMC_RET1(handle, TRNG_E_NOT_IMPLEMENTED);
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}
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switch (smc_fid) {
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case ARM_TRNG_VERSION:
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SMC_RET1(handle, MAKE_SMCCC_VERSION(
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TRNG_VERSION_MAJOR, TRNG_VERSION_MINOR
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));
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break; /* unreachable */
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case ARM_TRNG_FEATURES:
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if (is_trng_fid((uint32_t)x1)) {
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SMC_RET1(handle, TRNG_E_SUCCESS);
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} else {
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SMC_RET1(handle, TRNG_E_NOT_SUPPORTED);
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}
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break; /* unreachable */
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case ARM_TRNG_GET_UUID:
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SMC_UUID_RET(handle, plat_trng_uuid);
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break; /* unreachable */
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case ARM_TRNG_RND32:
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return trng_rnd32((uint32_t)x1, handle);
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case ARM_TRNG_RND64:
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return trng_rnd64((uint32_t)x1, handle);
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default:
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WARN("Unimplemented TRNG Service Call: 0x%x\n",
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smc_fid);
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SMC_RET1(handle, TRNG_E_NOT_IMPLEMENTED);
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break; /* unreachable */
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}
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}
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