/* * Exynos4210 Pseudo Random Number Generator Emulation * * Copyright (c) 2017 Krzysztof Kozlowski * * 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. * * You should have received a copy of the GNU General Public License along * with this program; if not, see . */ #include "qemu/osdep.h" #include "hw/sysbus.h" #include "migration/vmstate.h" #include "qapi/error.h" #include "qemu/log.h" #include "qemu/guest-random.h" #include "qemu/module.h" #include "qom/object.h" #define DEBUG_EXYNOS_RNG 0 #define DPRINTF(fmt, ...) \ do { \ if (DEBUG_EXYNOS_RNG) { \ printf("exynos4210_rng: " fmt, ## __VA_ARGS__); \ } \ } while (0) #define TYPE_EXYNOS4210_RNG "exynos4210.rng" OBJECT_DECLARE_SIMPLE_TYPE(Exynos4210RngState, EXYNOS4210_RNG) /* * Exynos4220, PRNG, only polling mode is supported. */ /* RNG_CONTROL_1 register bitfields, reset value: 0x0 */ #define EXYNOS4210_RNG_CONTROL_1_PRNG 0x8 #define EXYNOS4210_RNG_CONTROL_1_START_INIT BIT(4) /* RNG_STATUS register bitfields, reset value: 0x1 */ #define EXYNOS4210_RNG_STATUS_PRNG_ERROR BIT(7) #define EXYNOS4210_RNG_STATUS_PRNG_DONE BIT(5) #define EXYNOS4210_RNG_STATUS_MSG_DONE BIT(4) #define EXYNOS4210_RNG_STATUS_PARTIAL_DONE BIT(3) #define EXYNOS4210_RNG_STATUS_PRNG_BUSY BIT(2) #define EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE BIT(1) #define EXYNOS4210_RNG_STATUS_BUFFER_READY BIT(0) #define EXYNOS4210_RNG_STATUS_WRITE_MASK (EXYNOS4210_RNG_STATUS_PRNG_DONE \ | EXYNOS4210_RNG_STATUS_MSG_DONE \ | EXYNOS4210_RNG_STATUS_PARTIAL_DONE) #define EXYNOS4210_RNG_CONTROL_1 0x0 #define EXYNOS4210_RNG_STATUS 0x10 #define EXYNOS4210_RNG_SEED_IN 0x140 #define EXYNOS4210_RNG_SEED_IN_OFFSET(n) (EXYNOS4210_RNG_SEED_IN + (n * 0x4)) #define EXYNOS4210_RNG_PRNG 0x160 #define EXYNOS4210_RNG_PRNG_OFFSET(n) (EXYNOS4210_RNG_PRNG + (n * 0x4)) #define EXYNOS4210_RNG_PRNG_NUM 5 #define EXYNOS4210_RNG_REGS_MEM_SIZE 0x200 struct Exynos4210RngState { SysBusDevice parent_obj; MemoryRegion iomem; int32_t randr_value[EXYNOS4210_RNG_PRNG_NUM]; /* bits from 0 to EXYNOS4210_RNG_PRNG_NUM if given seed register was set */ uint32_t seed_set; /* Register values */ uint32_t reg_control; uint32_t reg_status; }; static bool exynos4210_rng_seed_ready(const Exynos4210RngState *s) { uint32_t mask = MAKE_64BIT_MASK(0, EXYNOS4210_RNG_PRNG_NUM); /* Return true if all the seed-set bits are set. */ return (s->seed_set & mask) == mask; } static void exynos4210_rng_set_seed(Exynos4210RngState *s, unsigned int i, uint64_t val) { /* * We actually ignore the seed and always generate true random numbers. * Theoretically this should not match the device as Exynos has * a Pseudo Random Number Generator but testing shown that it always * generates random numbers regardless of the seed value. */ s->seed_set |= BIT(i); /* If all seeds were written, update the status to reflect it */ if (exynos4210_rng_seed_ready(s)) { s->reg_status |= EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE; } else { s->reg_status &= ~EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE; } } static void exynos4210_rng_run_engine(Exynos4210RngState *s) { Error *err = NULL; /* Seed set? */ if ((s->reg_status & EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE) == 0) { goto out; } /* PRNG engine chosen? */ if ((s->reg_control & EXYNOS4210_RNG_CONTROL_1_PRNG) == 0) { goto out; } /* PRNG engine started? */ if ((s->reg_control & EXYNOS4210_RNG_CONTROL_1_START_INIT) == 0) { goto out; } /* Get randoms */ if (qemu_guest_getrandom(s->randr_value, sizeof(s->randr_value), &err)) { error_report_err(err); } else { /* Notify that PRNG is ready */ s->reg_status |= EXYNOS4210_RNG_STATUS_PRNG_DONE; } out: /* Always clear start engine bit */ s->reg_control &= ~EXYNOS4210_RNG_CONTROL_1_START_INIT; } static uint64_t exynos4210_rng_read(void *opaque, hwaddr offset, unsigned size) { Exynos4210RngState *s = (Exynos4210RngState *)opaque; uint32_t val = 0; assert(size == 4); switch (offset) { case EXYNOS4210_RNG_CONTROL_1: val = s->reg_control; break; case EXYNOS4210_RNG_STATUS: val = s->reg_status; break; case EXYNOS4210_RNG_PRNG_OFFSET(0): case EXYNOS4210_RNG_PRNG_OFFSET(1): case EXYNOS4210_RNG_PRNG_OFFSET(2): case EXYNOS4210_RNG_PRNG_OFFSET(3): case EXYNOS4210_RNG_PRNG_OFFSET(4): val = s->randr_value[(offset - EXYNOS4210_RNG_PRNG_OFFSET(0)) / 4]; DPRINTF("returning random @0x%" HWADDR_PRIx ": 0x%" PRIx32 "\n", offset, val); break; default: qemu_log_mask(LOG_GUEST_ERROR, "%s: bad read offset 0x%" HWADDR_PRIx "\n", __func__, offset); } return val; } static void exynos4210_rng_write(void *opaque, hwaddr offset, uint64_t val, unsigned size) { Exynos4210RngState *s = (Exynos4210RngState *)opaque; assert(size == 4); switch (offset) { case EXYNOS4210_RNG_CONTROL_1: DPRINTF("RNG_CONTROL_1 = 0x%" PRIx64 "\n", val); s->reg_control = val; exynos4210_rng_run_engine(s); break; case EXYNOS4210_RNG_STATUS: /* For clearing status fields */ s->reg_status &= ~EXYNOS4210_RNG_STATUS_WRITE_MASK; s->reg_status |= val & EXYNOS4210_RNG_STATUS_WRITE_MASK; break; case EXYNOS4210_RNG_SEED_IN_OFFSET(0): case EXYNOS4210_RNG_SEED_IN_OFFSET(1): case EXYNOS4210_RNG_SEED_IN_OFFSET(2): case EXYNOS4210_RNG_SEED_IN_OFFSET(3): case EXYNOS4210_RNG_SEED_IN_OFFSET(4): exynos4210_rng_set_seed(s, (offset - EXYNOS4210_RNG_SEED_IN_OFFSET(0)) / 4, val); break; default: qemu_log_mask(LOG_GUEST_ERROR, "%s: bad write offset 0x%" HWADDR_PRIx "\n", __func__, offset); } } static const MemoryRegionOps exynos4210_rng_ops = { .read = exynos4210_rng_read, .write = exynos4210_rng_write, .endianness = DEVICE_NATIVE_ENDIAN, .valid.min_access_size = 4, .valid.max_access_size = 4, }; static void exynos4210_rng_reset(DeviceState *dev) { Exynos4210RngState *s = EXYNOS4210_RNG(dev); s->reg_control = 0; s->reg_status = EXYNOS4210_RNG_STATUS_BUFFER_READY; memset(s->randr_value, 0, sizeof(s->randr_value)); s->seed_set = 0; } static void exynos4210_rng_init(Object *obj) { Exynos4210RngState *s = EXYNOS4210_RNG(obj); SysBusDevice *dev = SYS_BUS_DEVICE(obj); memory_region_init_io(&s->iomem, obj, &exynos4210_rng_ops, s, TYPE_EXYNOS4210_RNG, EXYNOS4210_RNG_REGS_MEM_SIZE); sysbus_init_mmio(dev, &s->iomem); } static const VMStateDescription exynos4210_rng_vmstate = { .name = TYPE_EXYNOS4210_RNG, .version_id = 1, .minimum_version_id = 1, .fields = (const VMStateField[]) { VMSTATE_INT32_ARRAY(randr_value, Exynos4210RngState, EXYNOS4210_RNG_PRNG_NUM), VMSTATE_UINT32(seed_set, Exynos4210RngState), VMSTATE_UINT32(reg_status, Exynos4210RngState), VMSTATE_UINT32(reg_control, Exynos4210RngState), VMSTATE_END_OF_LIST() } }; static void exynos4210_rng_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); device_class_set_legacy_reset(dc, exynos4210_rng_reset); dc->vmsd = &exynos4210_rng_vmstate; } static const TypeInfo exynos4210_rng_info = { .name = TYPE_EXYNOS4210_RNG, .parent = TYPE_SYS_BUS_DEVICE, .instance_size = sizeof(Exynos4210RngState), .instance_init = exynos4210_rng_init, .class_init = exynos4210_rng_class_init, }; static void exynos4210_rng_register(void) { type_register_static(&exynos4210_rng_info); } type_init(exynos4210_rng_register)