blob: ccdd3aa46e543e7f8ff9358f407af829ce563de4 [file] [log] [blame]
/*
* Copyright (c) 2018 Oticon A/S
*
* SPDX-License-Identifier: Apache-2.0
*
* Pseudo-random entropy generator for the ARCH_POSIX architecture:
* Following the principle of reproducibility of the native_posix board
* this entropy device will always generate the same random sequence when
* initialized with the same seed
*
* This entropy source should only be used for testing.
*/
#define DT_DRV_COMPAT zephyr_native_posix_rng
#include <zephyr/device.h>
#include <zephyr/drivers/entropy.h>
#include <zephyr/init.h>
#include <zephyr/sys/util.h>
#include <stdlib.h>
#include <string.h>
#include <zephyr/arch/posix/posix_trace.h>
#include "soc.h"
#include "cmdline.h" /* native_posix command line options header */
#include "nsi_host_trampolines.h"
#include "fake_entropy_native_bottom.h"
static unsigned int seed = 0x5678;
static bool seed_random;
static int entropy_native_posix_get_entropy(const struct device *dev,
uint8_t *buffer,
uint16_t length)
{
ARG_UNUSED(dev);
while (length) {
/*
* Note that only 1 thread (Zephyr thread or HW models), runs at
* a time, therefore there is no need to use random_r()
*/
long value = nsi_host_random();
size_t to_copy = MIN(length, sizeof(long int));
memcpy(buffer, &value, to_copy);
buffer += to_copy;
length -= to_copy;
}
return 0;
}
static int entropy_native_posix_get_entropy_isr(const struct device *dev,
uint8_t *buf,
uint16_t len, uint32_t flags)
{
ARG_UNUSED(flags);
/*
* entropy_native_posix_get_entropy() is also safe for ISRs
* and always produces data.
*/
entropy_native_posix_get_entropy(dev, buf, len);
return len;
}
static int entropy_native_posix_init(const struct device *dev)
{
ARG_UNUSED(dev);
entropy_native_seed(seed, seed_random);
posix_print_warning("WARNING: "
"Using a test - not safe - entropy source\n");
return 0;
}
static const struct entropy_driver_api entropy_native_posix_api_funcs = {
.get_entropy = entropy_native_posix_get_entropy,
.get_entropy_isr = entropy_native_posix_get_entropy_isr
};
DEVICE_DT_INST_DEFINE(0,
entropy_native_posix_init, NULL,
NULL, NULL,
PRE_KERNEL_1, CONFIG_ENTROPY_INIT_PRIORITY,
&entropy_native_posix_api_funcs);
static void add_fake_entropy_option(void)
{
static struct args_struct_t entropy_options[] = {
{
.option = "seed",
.name = "r_seed",
.type = 'u',
.dest = (void *)&seed,
.descript = "A 32-bit integer seed value for the entropy device, such as "
"97229 (decimal), 0x17BCD (hex), or 0275715 (octal)"
},
{
.is_switch = true,
.option = "seed-random",
.type = 'b',
.dest = (void *)&seed_random,
.descript = "Seed the random generator from /dev/urandom. "
"Note your test may not be reproducible if you set this option"
},
ARG_TABLE_ENDMARKER
};
native_add_command_line_opts(entropy_options);
}
NATIVE_TASK(add_fake_entropy_option, PRE_BOOT_1, 10);