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- /*
- * Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
- *
- * Licensed under the Apache License 2.0 (the "License"). You may not use
- * this file except in compliance with the License. You can obtain a copy
- * in the file LICENSE in the source distribution or at
- * https://www.openssl.org/source/license.html
- */
- #include "internal/cryptlib.h"
- #include <openssl/opensslconf.h>
- #include "crypto/rand_pool.h"
- #include "prov/seeding.h"
- #ifdef OPENSSL_RAND_SEED_RDCPU
- #include "crypto/arm_arch.h"
- size_t OPENSSL_rndrrs_bytes(unsigned char *buf, size_t len);
- static size_t get_hardware_random_value(unsigned char *buf, size_t len);
- /*
- * Acquire entropy using Arm-specific cpu instructions
- *
- * Uses the RNDRRS instruction. RNDR is never needed since
- * RNDRRS will always be available if RNDR is an available
- * instruction.
- *
- * Returns the total entropy count, if it exceeds the requested
- * entropy count. Otherwise, returns an entropy count of 0.
- */
- size_t ossl_prov_acquire_entropy_from_cpu(RAND_POOL *pool)
- {
- size_t bytes_needed;
- unsigned char *buffer;
- bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
- if (bytes_needed > 0) {
- buffer = ossl_rand_pool_add_begin(pool, bytes_needed);
- if (buffer != NULL) {
- if (get_hardware_random_value(buffer, bytes_needed) == bytes_needed)
- ossl_rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
- else
- ossl_rand_pool_add_end(pool, 0, 0);
- }
- }
- return ossl_rand_pool_entropy_available(pool);
- }
- static size_t get_hardware_random_value(unsigned char *buf, size_t len)
- {
- /* Always use RNDRRS or nothing */
- if (OPENSSL_armcap_P & ARMV8_RNG) {
- if (OPENSSL_rndrrs_bytes(buf, len) != len)
- return 0;
- } else {
- return 0;
- }
- return len;
- }
- #else
- NON_EMPTY_TRANSLATION_UNIT
- #endif /* OPENSSL_RAND_SEED_RDCPU */
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