878ec29b9c
Record/replay feature of icount allows deterministic running of execution scenarios. Some CPUs and peripheral devices read random numbers from external sources making deterministic execution impossible. This patch adds recording and replaying of random read operations into guest-random module, which is used by the virtual hardware. Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru> Message-Id: <157675984852.14505.15709141760677102489.stgit@pasha-Precision-3630-Tower> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
102 lines
2.5 KiB
C
102 lines
2.5 KiB
C
/*
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* QEMU guest-visible random functions
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*
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* Copyright 2019 Linaro, Ltd.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "qapi/error.h"
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#include "qemu/guest-random.h"
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#include "crypto/random.h"
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#include "sysemu/replay.h"
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static __thread GRand *thread_rand;
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static bool deterministic;
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static int glib_random_bytes(void *buf, size_t len)
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{
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GRand *rand = thread_rand;
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size_t i;
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uint32_t x;
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if (unlikely(rand == NULL)) {
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/* Thread not initialized for a cpu, or main w/o -seed. */
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thread_rand = rand = g_rand_new();
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}
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for (i = 0; i + 4 <= len; i += 4) {
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x = g_rand_int(rand);
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__builtin_memcpy(buf + i, &x, 4);
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}
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if (i < len) {
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x = g_rand_int(rand);
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__builtin_memcpy(buf + i, &x, i - len);
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}
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return 0;
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}
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int qemu_guest_getrandom(void *buf, size_t len, Error **errp)
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{
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int ret;
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if (replay_mode == REPLAY_MODE_PLAY) {
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return replay_read_random(buf, len);
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}
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if (unlikely(deterministic)) {
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/* Deterministic implementation using Glib's Mersenne Twister. */
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ret = glib_random_bytes(buf, len);
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} else {
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/* Non-deterministic implementation using crypto routines. */
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ret = qcrypto_random_bytes(buf, len, errp);
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}
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if (replay_mode == REPLAY_MODE_RECORD) {
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replay_save_random(ret, buf, len);
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}
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return ret;
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}
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void qemu_guest_getrandom_nofail(void *buf, size_t len)
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{
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(void)qemu_guest_getrandom(buf, len, &error_fatal);
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}
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uint64_t qemu_guest_random_seed_thread_part1(void)
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{
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if (deterministic) {
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uint64_t ret;
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glib_random_bytes(&ret, sizeof(ret));
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return ret;
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}
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return 0;
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}
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void qemu_guest_random_seed_thread_part2(uint64_t seed)
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{
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g_assert(thread_rand == NULL);
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if (deterministic) {
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thread_rand =
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g_rand_new_with_seed_array((const guint32 *)&seed,
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sizeof(seed) / sizeof(guint32));
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}
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}
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int qemu_guest_random_seed_main(const char *optarg, Error **errp)
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{
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unsigned long long seed;
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if (parse_uint_full(optarg, &seed, 0)) {
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error_setg(errp, "Invalid seed number: %s", optarg);
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return -1;
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} else {
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deterministic = true;
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qemu_guest_random_seed_thread_part2(seed);
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return 0;
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}
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}
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