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hw/misc: Add npcm7xx random number generator

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The RNG module returns a byte of randomness when the Data Valid bit is
set.

This implementation ignores the prescaler setting, and loads a new value
into RNGD every time RNGCS is read while the RNG is enabled and random
data is available.

A qtest featuring some simple randomness tests is included.

Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Havard Skinnemoen 2020-10-23 14:06:35 -07:00 committed by Peter Maydell
parent 7d378ed6e3
commit 326ccfe240
9 changed files with 510 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
docs/system/arm/nuvoton.rst
View File

@ -38,6 +38,7 @@ Supported devices
* DDR4 memory controller (dummy interface indicating memory training is done)
* OTP controllers (no protection features)
* Flash Interface Unit (FIU; no protection features)
* Random Number Generator (RNG)
Missing devices
---------------
@ -59,7 +60,6 @@ Missing devices
* Peripheral SPI controller (PSPI)
* Analog to Digital Converter (ADC)
* SD/MMC host
* Random Number Generator (RNG)
* PECI interface
* Pulse Width Modulation (PWM)
* Tachometer

7
hw/arm/npcm7xx.c
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@ -44,6 +44,7 @@
#define NPCM7XX_GCR_BA (0xf0800000)
#define NPCM7XX_CLK_BA (0xf0801000)
#define NPCM7XX_MC_BA (0xf0824000)
#define NPCM7XX_RNG_BA (0xf000b000)
/* Internal AHB SRAM */
#define NPCM7XX_RAM3_BA (0xc0008000)
@ -256,6 +257,7 @@ static void npcm7xx_init(Object *obj)
object_initialize_child(obj, "otp2", &s->fuse_array,
TYPE_NPCM7XX_FUSE_ARRAY);
object_initialize_child(obj, "mc", &s->mc, TYPE_NPCM7XX_MC);
object_initialize_child(obj, "rng", &s->rng, TYPE_NPCM7XX_RNG);
for (i = 0; i < ARRAY_SIZE(s->tim); i++) {
object_initialize_child(obj, "tim[*]", &s->tim[i], TYPE_NPCM7XX_TIMER);
@ -374,6 +376,10 @@ static void npcm7xx_realize(DeviceState *dev, Error **errp)
serial_hd(i), DEVICE_LITTLE_ENDIAN);
}
/* Random Number Generator. Cannot fail. */
sysbus_realize(SYS_BUS_DEVICE(&s->rng), &error_abort);
sysbus_mmio_map(SYS_BUS_DEVICE(&s->rng), 0, NPCM7XX_RNG_BA);
/*
* Flash Interface Unit (FIU). Can fail if incorrect number of chip selects
* specified, but this is a programming error.
@ -412,7 +418,6 @@ static void npcm7xx_realize(DeviceState *dev, Error **errp)
create_unimplemented_device("npcm7xx.vdmx", 0xe0800000, 4 * KiB);
create_unimplemented_device("npcm7xx.pcierc", 0xe1000000, 64 * KiB);
create_unimplemented_device("npcm7xx.kcs", 0xf0007000, 4 * KiB);
create_unimplemented_device("npcm7xx.rng", 0xf000b000, 4 * KiB);
create_unimplemented_device("npcm7xx.adc", 0xf000c000, 4 * KiB);
create_unimplemented_device("npcm7xx.gfxi", 0xf000e000, 4 * KiB);
create_unimplemented_device("npcm7xx.gpio[0]", 0xf0010000, 4 * KiB);

1
hw/misc/meson.build
View File

@ -59,6 +59,7 @@ softmmu_ss.add(when: 'CONFIG_MAINSTONE', if_true: files('mst_fpga.c'))
softmmu_ss.add(when: 'CONFIG_NPCM7XX', if_true: files(
'npcm7xx_clk.c',
'npcm7xx_gcr.c',
'npcm7xx_rng.c',
))
softmmu_ss.add(when: 'CONFIG_OMAP', if_true: files(
'omap_clk.c',

180
hw/misc/npcm7xx_rng.c Normal file
View File

@ -0,0 +1,180 @@
/*
* Nuvoton NPCM7xx Random Number Generator.
*
* Copyright 2020 Google LLC
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "qemu/osdep.h"
#include "hw/misc/npcm7xx_rng.h"
#include "migration/vmstate.h"
#include "qemu/bitops.h"
#include "qemu/guest-random.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "qemu/units.h"
#include "trace.h"
#define NPCM7XX_RNG_REGS_SIZE (4 * KiB)
#define NPCM7XX_RNGCS (0x00)
#define NPCM7XX_RNGCS_CLKP(rv) extract32(rv, 2, 4)
#define NPCM7XX_RNGCS_DVALID BIT(1)
#define NPCM7XX_RNGCS_RNGE BIT(0)
#define NPCM7XX_RNGD (0x04)
#define NPCM7XX_RNGMODE (0x08)
#define NPCM7XX_RNGMODE_NORMAL (0x02)
static bool npcm7xx_rng_is_enabled(NPCM7xxRNGState *s)
{
return (s->rngcs & NPCM7XX_RNGCS_RNGE) &&
(s->rngmode == NPCM7XX_RNGMODE_NORMAL);
}
static uint64_t npcm7xx_rng_read(void *opaque, hwaddr offset, unsigned size)
{
NPCM7xxRNGState *s = opaque;
uint64_t value = 0;
switch (offset) {
case NPCM7XX_RNGCS:
/*
* If the RNG is enabled, but we don't have any valid random data, try
* obtaining some and update the DVALID bit accordingly.
*/
if (!npcm7xx_rng_is_enabled(s)) {
s->rngcs &= ~NPCM7XX_RNGCS_DVALID;
} else if (!(s->rngcs & NPCM7XX_RNGCS_DVALID)) {
uint8_t byte = 0;
if (qemu_guest_getrandom(&byte, sizeof(byte), NULL) == 0) {
s->rngd = byte;
s->rngcs |= NPCM7XX_RNGCS_DVALID;
}
}
value = s->rngcs;
break;
case NPCM7XX_RNGD:
if (npcm7xx_rng_is_enabled(s) && s->rngcs & NPCM7XX_RNGCS_DVALID) {
s->rngcs &= ~NPCM7XX_RNGCS_DVALID;
value = s->rngd;
s->rngd = 0;
}
break;
case NPCM7XX_RNGMODE:
value = s->rngmode;
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: read from invalid offset 0x%" HWADDR_PRIx "\n",
DEVICE(s)->canonical_path, offset);
break;
}
trace_npcm7xx_rng_read(offset, value, size);
return value;
}
static void npcm7xx_rng_write(void *opaque, hwaddr offset, uint64_t value,
unsigned size)
{
NPCM7xxRNGState *s = opaque;
trace_npcm7xx_rng_write(offset, value, size);
switch (offset) {
case NPCM7XX_RNGCS:
s->rngcs &= NPCM7XX_RNGCS_DVALID;
s->rngcs |= value & ~NPCM7XX_RNGCS_DVALID;
break;
case NPCM7XX_RNGD:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: write to read-only register @ 0x%" HWADDR_PRIx "\n",
DEVICE(s)->canonical_path, offset);
break;
case NPCM7XX_RNGMODE:
s->rngmode = value;
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"%s: write to invalid offset 0x%" HWADDR_PRIx "\n",
DEVICE(s)->canonical_path, offset);
break;
}
}
static const MemoryRegionOps npcm7xx_rng_ops = {
.read = npcm7xx_rng_read,
.write = npcm7xx_rng_write,
.endianness = DEVICE_LITTLE_ENDIAN,
.valid = {
.min_access_size = 1,
.max_access_size = 4,
.unaligned = false,
},
};
static void npcm7xx_rng_enter_reset(Object *obj, ResetType type)
{
NPCM7xxRNGState *s = NPCM7XX_RNG(obj);
s->rngcs = 0;
s->rngd = 0;
s->rngmode = 0;
}
static void npcm7xx_rng_init(Object *obj)
{
NPCM7xxRNGState *s = NPCM7XX_RNG(obj);
memory_region_init_io(&s->iomem, obj, &npcm7xx_rng_ops, s, "regs",
NPCM7XX_RNG_REGS_SIZE);
sysbus_init_mmio(&s->parent, &s->iomem);
}
static const VMStateDescription vmstate_npcm7xx_rng = {
.name = "npcm7xx-rng",
.version_id = 0,
.minimum_version_id = 0,
.fields = (VMStateField[]) {
VMSTATE_UINT8(rngcs, NPCM7xxRNGState),
VMSTATE_UINT8(rngd, NPCM7xxRNGState),
VMSTATE_UINT8(rngmode, NPCM7xxRNGState),
VMSTATE_END_OF_LIST(),
},
};
static void npcm7xx_rng_class_init(ObjectClass *klass, void *data)
{
ResettableClass *rc = RESETTABLE_CLASS(klass);
DeviceClass *dc = DEVICE_CLASS(klass);
dc->desc = "NPCM7xx Random Number Generator";
dc->vmsd = &vmstate_npcm7xx_rng;
rc->phases.enter = npcm7xx_rng_enter_reset;
}
static const TypeInfo npcm7xx_rng_types[] = {
{
.name = TYPE_NPCM7XX_RNG,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(NPCM7xxRNGState),
.class_init = npcm7xx_rng_class_init,
.instance_init = npcm7xx_rng_init,
},
};
DEFINE_TYPES(npcm7xx_rng_types);

4
hw/misc/trace-events
View File

@ -118,6 +118,10 @@ npcm7xx_clk_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 " valu
npcm7xx_gcr_read(uint64_t offset, uint32_t value) " offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
npcm7xx_gcr_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
# npcm7xx_rng.c
npcm7xx_rng_read(uint64_t offset, uint64_t value, unsigned size) "offset: 0x%04" PRIx64 " value: 0x%02" PRIx64 " size: %u"
npcm7xx_rng_write(uint64_t offset, uint64_t value, unsigned size) "offset: 0x%04" PRIx64 " value: 0x%02" PRIx64 " size: %u"
# stm32f4xx_syscfg.c
stm32f4xx_syscfg_set_irq(int gpio, int line, int level) "Interupt: GPIO: %d, Line: %d; Level: %d"
stm32f4xx_pulse_exti(int irq) "Pulse EXTI: %d"

2
include/hw/arm/npcm7xx.h
View File

@ -21,6 +21,7 @@
#include "hw/mem/npcm7xx_mc.h"
#include "hw/misc/npcm7xx_clk.h"
#include "hw/misc/npcm7xx_gcr.h"
#include "hw/misc/npcm7xx_rng.h"
#include "hw/nvram/npcm7xx_otp.h"
#include "hw/timer/npcm7xx_timer.h"
#include "hw/ssi/npcm7xx_fiu.h"
@ -75,6 +76,7 @@ typedef struct NPCM7xxState {
NPCM7xxOTPState key_storage;
NPCM7xxOTPState fuse_array;
NPCM7xxMCState mc;
NPCM7xxRNGState rng;
NPCM7xxFIUState fiu[2];
} NPCM7xxState;

34
include/hw/misc/npcm7xx_rng.h Normal file
View File

@ -0,0 +1,34 @@
/*
* Nuvoton NPCM7xx Random Number Generator.
*
* Copyright 2020 Google LLC
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#ifndef NPCM7XX_RNG_H
#define NPCM7XX_RNG_H
#include "hw/sysbus.h"
typedef struct NPCM7xxRNGState {
SysBusDevice parent;
MemoryRegion iomem;
uint8_t rngcs;
uint8_t rngd;
uint8_t rngmode;
} NPCM7xxRNGState;
#define TYPE_NPCM7XX_RNG "npcm7xx-rng"
#define NPCM7XX_RNG(obj) OBJECT_CHECK(NPCM7xxRNGState, (obj), TYPE_NPCM7XX_RNG)
#endif /* NPCM7XX_RNG_H */

5
tests/qtest/meson.build
View File

@ -133,7 +133,10 @@ qtests_sparc64 = \
(config_all_devices.has_key('CONFIG_ISA_TESTDEV') ? ['endianness-test'] : []) + \
['prom-env-test', 'boot-serial-test']
qtests_npcm7xx = ['npcm7xx_timer-test', 'npcm7xx_watchdog_timer-test']
qtests_npcm7xx = \
['npcm7xx_rng-test',
'npcm7xx_timer-test',
'npcm7xx_watchdog_timer-test']
qtests_arm = \
(config_all_devices.has_key('CONFIG_PFLASH_CFI02') ? ['pflash-cfi02-test'] : []) + \
(config_all_devices.has_key('CONFIG_NPCM7XX') ? qtests_npcm7xx : []) + \

278
tests/qtest/npcm7xx_rng-test.c Normal file
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@ -0,0 +1,278 @@
/*
* QTest testcase for the Nuvoton NPCM7xx Random Number Generator
*
* Copyright 2020 Google LLC
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "qemu/osdep.h"
#include <math.h>
#include "libqtest-single.h"
#include "qemu/bitops.h"
#define RNG_BASE_ADDR 0xf000b000
/* Control and Status Register */
#define RNGCS 0x00
# define DVALID BIT(1) /* Data Valid */
# define RNGE BIT(0) /* RNG Enable */
/* Data Register */
#define RNGD 0x04
/* Mode Register */
#define RNGMODE 0x08
# define ROSEL_NORMAL (2) /* RNG only works in this mode */
/* Number of bits to collect for randomness tests. */
#define TEST_INPUT_BITS (128)
static void rng_writeb(unsigned int offset, uint8_t value)
{
writeb(RNG_BASE_ADDR + offset, value);
}
static uint8_t rng_readb(unsigned int offset)
{
return readb(RNG_BASE_ADDR + offset);
}
/* Disable RNG and set normal ring oscillator mode. */
static void rng_reset(void)
{
rng_writeb(RNGCS, 0);
rng_writeb(RNGMODE, ROSEL_NORMAL);
}
/* Reset RNG and then enable it. */
static void rng_reset_enable(void)
{
rng_reset();
rng_writeb(RNGCS, RNGE);
}
/* Wait until Data Valid bit is set. */
static bool rng_wait_ready(void)
{
/* qemu_guest_getrandom may fail. Assume it won't fail 10 times in a row. */
int retries = 10;
while (retries-- > 0) {
if (rng_readb(RNGCS) & DVALID) {
return true;
}
}
return false;
}
/*
* Perform a frequency (monobit) test, as defined by NIST SP 800-22, on the
* sequence in buf and return the P-value. This represents the probability of a
* truly random sequence having the same proportion of zeros and ones as the
* sequence in buf.
*
* An RNG which always returns 0x00 or 0xff, or has some bits stuck at 0 or 1,
* will fail this test. However, an RNG which always returns 0x55, 0xf0 or some
* other value with an equal number of zeroes and ones will pass.
*/
static double calc_monobit_p(const uint8_t *buf, unsigned int len)
{
unsigned int i;
double s_obs;
int sn = 0;
for (i = 0; i < len; i++) {
/*
* Each 1 counts as 1, each 0 counts as -1.
* s = cp - (8 - cp) = 2 * cp - 8
*/
sn += 2 * ctpop8(buf[i]) - 8;
}
s_obs = abs(sn) / sqrt(len * BITS_PER_BYTE);
return erfc(s_obs / sqrt(2));
}
/*
* Perform a runs test, as defined by NIST SP 800-22, and return the P-value.
* This represents the probability of a truly random sequence having the same
* number of runs (i.e. uninterrupted sequences of identical bits) as the
* sequence in buf.
*/
static double calc_runs_p(const unsigned long *buf, unsigned int nr_bits)
{
unsigned int j;
unsigned int k;
int nr_ones = 0;
int vn_obs = 0;
double pi;
g_assert(nr_bits % BITS_PER_LONG == 0);
for (j = 0; j < nr_bits / BITS_PER_LONG; j++) {
nr_ones += __builtin_popcountl(buf[j]);
}
pi = (double)nr_ones / nr_bits;
for (k = 0; k < nr_bits - 1; k++) {
vn_obs += !(test_bit(k, buf) ^ test_bit(k + 1, buf));
}
vn_obs += 1;
return erfc(fabs(vn_obs - 2 * nr_bits * pi * (1.0 - pi))
/ (2 * sqrt(2 * nr_bits) * pi * (1.0 - pi)));
}
/*
* Verifies that DVALID is clear, and RNGD reads zero, when RNGE is cleared,
* and DVALID eventually becomes set when RNGE is set.
*/
static void test_enable_disable(void)
{
/* Disable: DVALID should not be set, and RNGD should read zero */
rng_reset();
g_assert_cmphex(rng_readb(RNGCS), ==, 0);
g_assert_cmphex(rng_readb(RNGD), ==, 0);
/* Enable: DVALID should be set, but we can't make assumptions about RNGD */
rng_writeb(RNGCS, RNGE);
g_assert_true(rng_wait_ready());
g_assert_cmphex(rng_readb(RNGCS), ==, DVALID | RNGE);
/* Disable: DVALID should not be set, and RNGD should read zero */
rng_writeb(RNGCS, 0);
g_assert_cmphex(rng_readb(RNGCS), ==, 0);
g_assert_cmphex(rng_readb(RNGD), ==, 0);
}
/*
* Verifies that the RNG only produces data when RNGMODE is set to 'normal'
* ring oscillator mode.
*/
static void test_rosel(void)
{
rng_reset_enable();
g_assert_true(rng_wait_ready());
rng_writeb(RNGMODE, 0);
g_assert_false(rng_wait_ready());
rng_writeb(RNGMODE, ROSEL_NORMAL);
g_assert_true(rng_wait_ready());
rng_writeb(RNGMODE, 0);
g_assert_false(rng_wait_ready());
}
/*
* Verifies that a continuous sequence of bits collected after enabling the RNG
* satisfies a monobit test.
*/
static void test_continuous_monobit(void)
{
uint8_t buf[TEST_INPUT_BITS / BITS_PER_BYTE];
unsigned int i;
rng_reset_enable();
for (i = 0; i < sizeof(buf); i++) {
g_assert_true(rng_wait_ready());
buf[i] = rng_readb(RNGD);
}
g_assert_cmpfloat(calc_monobit_p(buf, sizeof(buf)), >, 0.01);
}
/*
* Verifies that a continuous sequence of bits collected after enabling the RNG
* satisfies a runs test.
*/
static void test_continuous_runs(void)
{
union {
unsigned long l[TEST_INPUT_BITS / BITS_PER_LONG];
uint8_t c[TEST_INPUT_BITS / BITS_PER_BYTE];
} buf;
unsigned int i;
rng_reset_enable();
for (i = 0; i < sizeof(buf); i++) {
g_assert_true(rng_wait_ready());
buf.c[i] = rng_readb(RNGD);
}
g_assert_cmpfloat(calc_runs_p(buf.l, sizeof(buf) * BITS_PER_BYTE), >, 0.01);
}
/*
* Verifies that the first data byte collected after enabling the RNG satisfies
* a monobit test.
*/
static void test_first_byte_monobit(void)
{
/* Enable, collect one byte, disable. Repeat until we have 100 bits. */
uint8_t buf[TEST_INPUT_BITS / BITS_PER_BYTE];
unsigned int i;
rng_reset();
for (i = 0; i < sizeof(buf); i++) {
rng_writeb(RNGCS, RNGE);
g_assert_true(rng_wait_ready());
buf[i] = rng_readb(RNGD);
rng_writeb(RNGCS, 0);
}
g_assert_cmpfloat(calc_monobit_p(buf, sizeof(buf)), >, 0.01);
}
/*
* Verifies that the first data byte collected after enabling the RNG satisfies
* a runs test.
*/
static void test_first_byte_runs(void)
{
/* Enable, collect one byte, disable. Repeat until we have 100 bits. */
union {
unsigned long l[TEST_INPUT_BITS / BITS_PER_LONG];
uint8_t c[TEST_INPUT_BITS / BITS_PER_BYTE];
} buf;
unsigned int i;
rng_reset();
for (i = 0; i < sizeof(buf); i++) {
rng_writeb(RNGCS, RNGE);
g_assert_true(rng_wait_ready());
buf.c[i] = rng_readb(RNGD);
rng_writeb(RNGCS, 0);
}
g_assert_cmpfloat(calc_runs_p(buf.l, sizeof(buf) * BITS_PER_BYTE), >, 0.01);
}
int main(int argc, char **argv)
{
int ret;
g_test_init(&argc, &argv, NULL);
g_test_set_nonfatal_assertions();
qtest_add_func("npcm7xx_rng/enable_disable", test_enable_disable);
qtest_add_func("npcm7xx_rng/rosel", test_rosel);
qtest_add_func("npcm7xx_rng/continuous/monobit", test_continuous_monobit);
qtest_add_func("npcm7xx_rng/continuous/runs", test_continuous_runs);
qtest_add_func("npcm7xx_rng/first_byte/monobit", test_first_byte_monobit);
qtest_add_func("npcm7xx_rng/first_byte/runs", test_first_byte_runs);
qtest_start("-machine npcm750-evb");
ret = g_test_run();
qtest_end();
return ret;
}