unicorn/qemu/target/riscv/cpu_helper.c
Alistair Francis ebc7b9371f target/riscv: Add virtual register swapping function
Backports commit 66e594f2800ddc55f908830bf9e8dc4cda1304fe from qemu
2020-03-22 01:30:22 -04:00

679 lines
22 KiB
C

/*
* RISC-V CPU helpers for qemu.
*
* Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
* Copyright (c) 2017-2018 SiFive, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2 or later, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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 <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "tcg-op.h"
#define RISCV_DEBUG_INTERRUPT 0
int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
{
#ifdef CONFIG_USER_ONLY
return 0;
#else
return env->priv;
#endif
}
#ifndef CONFIG_USER_ONLY
static int riscv_cpu_local_irq_pending(CPURISCVState *env)
{
target_ulong mstatus_mie = get_field(env->mstatus, MSTATUS_MIE);
target_ulong mstatus_sie = get_field(env->mstatus, MSTATUS_SIE);
target_ulong pending = atomic_read(&env->mip) & env->mie;
target_ulong mie = env->priv < PRV_M || (env->priv == PRV_M && mstatus_mie);
target_ulong sie = env->priv < PRV_S || (env->priv == PRV_S && mstatus_sie);
target_ulong irqs = (pending & ~env->mideleg & -mie) |
(pending & env->mideleg & -sie);
if (irqs) {
return ctz64(irqs); /* since non-zero */
} else {
return EXCP_NONE; /* indicates no pending interrupt */
}
}
#endif
bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
{
#if !defined(CONFIG_USER_ONLY)
if (interrupt_request & CPU_INTERRUPT_HARD) {
RISCVCPU *cpu = RISCV_CPU(cs->uc, cs);
CPURISCVState *env = &cpu->env;
int interruptno = riscv_cpu_local_irq_pending(env);
if (interruptno >= 0) {
cs->exception_index = RISCV_EXCP_INT_FLAG | interruptno;
riscv_cpu_do_interrupt(cs);
return true;
}
}
#endif
return false;
}
#if !defined(CONFIG_USER_ONLY)
void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env)
{
target_ulong mstatus_mask = MSTATUS_MXR | MSTATUS_SUM | MSTATUS_FS |
MSTATUS_SPP | MSTATUS_SPIE | MSTATUS_SIE;
bool current_virt = riscv_cpu_virt_enabled(env);
g_assert(riscv_has_ext(env, RVH));
#if defined(TARGET_RISCV64)
mstatus_mask |= MSTATUS64_UXL;
#endif
if (current_virt) {
/* Current V=1 and we are about to change to V=0 */
env->vsstatus = env->mstatus & mstatus_mask;
env->mstatus &= ~mstatus_mask;
env->mstatus |= env->mstatus_hs;
env->vstvec = env->stvec;
env->stvec = env->stvec_hs;
env->vsscratch = env->sscratch;
env->sscratch = env->sscratch_hs;
env->vsepc = env->sepc;
env->sepc = env->sepc_hs;
env->vscause = env->scause;
env->scause = env->scause_hs;
env->vstval = env->sbadaddr;
env->sbadaddr = env->stval_hs;
env->vsatp = env->satp;
env->satp = env->satp_hs;
} else {
/* Current V=0 and we are about to change to V=1 */
env->mstatus_hs = env->mstatus & mstatus_mask;
env->mstatus &= ~mstatus_mask;
env->mstatus |= env->vsstatus;
env->stvec_hs = env->stvec;
env->stvec = env->vstvec;
env->sscratch_hs = env->sscratch;
env->sscratch = env->vsscratch;
env->sepc_hs = env->sepc;
env->sepc = env->vsepc;
env->scause_hs = env->scause;
env->scause = env->vscause;
env->stval_hs = env->sbadaddr;
env->sbadaddr = env->vstval;
env->satp_hs = env->satp;
env->satp = env->vsatp;
}
}
bool riscv_cpu_virt_enabled(CPURISCVState *env)
{
if (!riscv_has_ext(env, RVH)) {
return false;
}
return get_field(env->virt, VIRT_ONOFF);
}
void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable)
{
if (!riscv_has_ext(env, RVH)) {
return;
}
env->virt = set_field(env->virt, VIRT_ONOFF, enable);
}
bool riscv_cpu_force_hs_excep_enabled(CPURISCVState *env)
{
if (!riscv_has_ext(env, RVH)) {
return false;
}
return get_field(env->virt, FORCE_HS_EXCEP);
}
void riscv_cpu_set_force_hs_excep(CPURISCVState *env, bool enable)
{
if (!riscv_has_ext(env, RVH)) {
return;
}
env->virt = set_field(env->virt, FORCE_HS_EXCEP, enable);
}
int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint32_t interrupts)
{
CPURISCVState *env = &cpu->env;
if (env->miclaim & interrupts) {
return -1;
} else {
env->miclaim |= interrupts;
return 0;
}
}
/* iothread_mutex must be held */
uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value)
{
CPURISCVState *env = &cpu->env;
uint32_t old, new, cmp = atomic_read(&env->mip);
do {
old = cmp;
new = (old & ~mask) | (value & mask);
cmp = atomic_cmpxchg(&env->mip, old, new);
} while (old != cmp);
if (new) {
cpu_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
} else {
cpu_reset_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
}
return old;
}
void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv)
{
if (newpriv > PRV_M) {
g_assert_not_reached();
}
if (newpriv == PRV_H) {
newpriv = PRV_U;
}
/* tlb_flush is unnecessary as mode is contained in mmu_idx */
env->priv = newpriv;
/*
* Clear the load reservation - otherwise a reservation placed in one
* context/process can be used by another, resulting in an SC succeeding
* incorrectly. Version 2.2 of the ISA specification explicitly requires
* this behaviour, while later revisions say that the kernel "should" use
* an SC instruction to force the yielding of a load reservation on a
* preemptive context switch. As a result, do both.
*/
env->load_res = -1;
}
/* get_physical_address - get the physical address for this virtual address
*
* Do a page table walk to obtain the physical address corresponding to a
* virtual address. Returns 0 if the translation was successful
*
* Adapted from Spike's mmu_t::translate and mmu_t::walk
*
*/
static int get_physical_address(CPURISCVState *env, hwaddr *physical,
int *prot, target_ulong addr,
int access_type, int mmu_idx)
{
/* NOTE: the env->pc value visible here will not be
* correct, but the value visible to the exception handler
* (riscv_cpu_do_interrupt) is correct */
int mode = mmu_idx;
if (mode == PRV_M && access_type != MMU_INST_FETCH) {
if (get_field(env->mstatus, MSTATUS_MPRV)) {
mode = get_field(env->mstatus, MSTATUS_MPP);
}
}
if (mode == PRV_M || !riscv_feature(env, RISCV_FEATURE_MMU)) {
*physical = addr;
*prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
return TRANSLATE_SUCCESS;
}
*prot = 0;
target_ulong base;
int levels, ptidxbits, ptesize, vm, sum;
int mxr = get_field(env->mstatus, MSTATUS_MXR);
if (env->priv_ver >= PRIV_VERSION_1_10_0) {
base = get_field(env->satp, SATP_PPN) << PGSHIFT;
sum = get_field(env->mstatus, MSTATUS_SUM);
vm = get_field(env->satp, SATP_MODE);
switch (vm) {
case VM_1_10_SV32:
levels = 2; ptidxbits = 10; ptesize = 4; break;
case VM_1_10_SV39:
levels = 3; ptidxbits = 9; ptesize = 8; break;
case VM_1_10_SV48:
levels = 4; ptidxbits = 9; ptesize = 8; break;
case VM_1_10_SV57:
levels = 5; ptidxbits = 9; ptesize = 8; break;
case VM_1_10_MBARE:
*physical = addr;
*prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
return TRANSLATE_SUCCESS;
default:
g_assert_not_reached();
}
} else {
base = env->sptbr << PGSHIFT;
sum = !get_field(env->mstatus, MSTATUS_PUM);
vm = get_field(env->mstatus, MSTATUS_VM);
switch (vm) {
case VM_1_09_SV32:
levels = 2; ptidxbits = 10; ptesize = 4; break;
case VM_1_09_SV39:
levels = 3; ptidxbits = 9; ptesize = 8; break;
case VM_1_09_SV48:
levels = 4; ptidxbits = 9; ptesize = 8; break;
case VM_1_09_MBARE:
*physical = addr;
*prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
return TRANSLATE_SUCCESS;
default:
g_assert_not_reached();
}
}
CPUState *cs = env_cpu(env);
int va_bits = PGSHIFT + levels * ptidxbits;
target_ulong mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
target_ulong masked_msbs = (addr >> (va_bits - 1)) & mask;
if (masked_msbs != 0 && masked_msbs != mask) {
return TRANSLATE_FAIL;
}
int ptshift = (levels - 1) * ptidxbits;
int i;
#if !TCG_OVERSIZED_GUEST
restart:
#endif
for (i = 0; i < levels; i++, ptshift -= ptidxbits) {
target_ulong idx = (addr >> (PGSHIFT + ptshift)) &
((1 << ptidxbits) - 1);
/* check that physical address of PTE is legal */
target_ulong pte_addr = base + idx * ptesize;
if (riscv_feature(env, RISCV_FEATURE_PMP) &&
!pmp_hart_has_privs(env, pte_addr, sizeof(target_ulong),
1 << MMU_DATA_LOAD, PRV_S)) {
return TRANSLATE_PMP_FAIL;
}
#if defined(TARGET_RISCV32)
target_ulong pte = ldl_phys(cs->as, pte_addr);
#elif defined(TARGET_RISCV64)
target_ulong pte = ldq_phys(cs->as, pte_addr);
#endif
target_ulong ppn = pte >> PTE_PPN_SHIFT;
if (!(pte & PTE_V)) {
/* Invalid PTE */
return TRANSLATE_FAIL;
} else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
/* Inner PTE, continue walking */
base = ppn << PGSHIFT;
} else if ((pte & (PTE_R | PTE_W | PTE_X)) == PTE_W) {
/* Reserved leaf PTE flags: PTE_W */
return TRANSLATE_FAIL;
} else if ((pte & (PTE_R | PTE_W | PTE_X)) == (PTE_W | PTE_X)) {
/* Reserved leaf PTE flags: PTE_W + PTE_X */
return TRANSLATE_FAIL;
} else if ((pte & PTE_U) && ((mode != PRV_U) &&
(!sum || access_type == MMU_INST_FETCH))) {
/* User PTE flags when not U mode and mstatus.SUM is not set,
or the access type is an instruction fetch */
return TRANSLATE_FAIL;
} else if (!(pte & PTE_U) && (mode != PRV_S)) {
/* Supervisor PTE flags when not S mode */
return TRANSLATE_FAIL;
} else if (ppn & ((1ULL << ptshift) - 1)) {
/* Misaligned PPN */
return TRANSLATE_FAIL;
} else if (access_type == MMU_DATA_LOAD && !((pte & PTE_R) ||
((pte & PTE_X) && mxr))) {
/* Read access check failed */
return TRANSLATE_FAIL;
} else if (access_type == MMU_DATA_STORE && !(pte & PTE_W)) {
/* Write access check failed */
return TRANSLATE_FAIL;
} else if (access_type == MMU_INST_FETCH && !(pte & PTE_X)) {
/* Fetch access check failed */
return TRANSLATE_FAIL;
} else {
/* if necessary, set accessed and dirty bits. */
target_ulong updated_pte = pte | PTE_A |
(access_type == MMU_DATA_STORE ? PTE_D : 0);
/* Page table updates need to be atomic with MTTCG enabled */
if (updated_pte != pte) {
/*
* - if accessed or dirty bits need updating, and the PTE is
* in RAM, then we do so atomically with a compare and swap.
* - if the PTE is in IO space or ROM, then it can't be updated
* and we return TRANSLATE_FAIL.
* - if the PTE changed by the time we went to update it, then
* it is no longer valid and we must re-walk the page table.
*/
MemoryRegion *mr;
hwaddr l = sizeof(target_ulong), addr1;
mr = address_space_translate(cs->as, pte_addr,
&addr1, &l, false);
if (memory_region_is_ram(mr)) {
target_ulong *pte_pa =
qemu_map_ram_ptr(env->uc, mr->ram_block, addr1);
#if TCG_OVERSIZED_GUEST
/* MTTCG is not enabled on oversized TCG guests so
* page table updates do not need to be atomic */
*pte_pa = pte = updated_pte;
#else
target_ulong old_pte =
atomic_cmpxchg(pte_pa, pte, updated_pte);
if (old_pte != pte) {
goto restart;
} else {
pte = updated_pte;
}
#endif
} else {
/* misconfigured PTE in ROM (AD bits are not preset) or
* PTE is in IO space and can't be updated atomically */
return TRANSLATE_FAIL;
}
}
/* for superpage mappings, make a fake leaf PTE for the TLB's
benefit. */
target_ulong vpn = addr >> PGSHIFT;
*physical = (ppn | (vpn & ((1L << ptshift) - 1))) << PGSHIFT;
/* set permissions on the TLB entry */
if ((pte & PTE_R) || ((pte & PTE_X) && mxr)) {
*prot |= PAGE_READ;
}
if ((pte & PTE_X)) {
*prot |= PAGE_EXEC;
}
/* add write permission on stores or if the page is already dirty,
so that we TLB miss on later writes to update the dirty bit */
if ((pte & PTE_W) &&
(access_type == MMU_DATA_STORE || (pte & PTE_D))) {
*prot |= PAGE_WRITE;
}
return TRANSLATE_SUCCESS;
}
}
return TRANSLATE_FAIL;
}
static void raise_mmu_exception(CPURISCVState *env, target_ulong address,
MMUAccessType access_type, bool pmp_violation)
{
CPUState *cs = env_cpu(env);
int page_fault_exceptions =
(env->priv_ver >= PRIV_VERSION_1_10_0) &&
get_field(env->satp, SATP_MODE) != VM_1_10_MBARE &&
!pmp_violation;
switch (access_type) {
case MMU_INST_FETCH:
cs->exception_index = page_fault_exceptions ?
RISCV_EXCP_INST_PAGE_FAULT : RISCV_EXCP_INST_ACCESS_FAULT;
break;
case MMU_DATA_LOAD:
cs->exception_index = page_fault_exceptions ?
RISCV_EXCP_LOAD_PAGE_FAULT : RISCV_EXCP_LOAD_ACCESS_FAULT;
break;
case MMU_DATA_STORE:
cs->exception_index = page_fault_exceptions ?
RISCV_EXCP_STORE_PAGE_FAULT : RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
break;
default:
g_assert_not_reached();
}
env->badaddr = address;
}
hwaddr riscv_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
{
RISCVCPU *cpu = RISCV_CPU(cs->uc, cs);
hwaddr phys_addr;
int prot;
int mmu_idx = cpu_mmu_index(&cpu->env, false);
if (get_physical_address(&cpu->env, &phys_addr, &prot, addr, 0, mmu_idx)) {
return -1;
}
return phys_addr;
}
void riscv_cpu_unassigned_access(CPUState *cs, hwaddr addr, bool is_write,
bool is_exec, int unused, unsigned size)
{
RISCVCPU *cpu = RISCV_CPU(cs->uc, cs);
CPURISCVState *env = &cpu->env;
if (is_write) {
cs->exception_index = RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
} else {
cs->exception_index = RISCV_EXCP_LOAD_ACCESS_FAULT;
}
env->badaddr = addr;
riscv_raise_exception(&cpu->env, cs->exception_index, GETPC());
}
void riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
MMUAccessType access_type, int mmu_idx,
uintptr_t retaddr)
{
RISCVCPU *cpu = RISCV_CPU(cs->uc, cs);
CPURISCVState *env = &cpu->env;
switch (access_type) {
case MMU_INST_FETCH:
cs->exception_index = RISCV_EXCP_INST_ADDR_MIS;
break;
case MMU_DATA_LOAD:
cs->exception_index = RISCV_EXCP_LOAD_ADDR_MIS;
break;
case MMU_DATA_STORE:
cs->exception_index = RISCV_EXCP_STORE_AMO_ADDR_MIS;
break;
default:
g_assert_not_reached();
}
env->badaddr = addr;
riscv_raise_exception(env, cs->exception_index, retaddr);
}
#endif
bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
MMUAccessType access_type, int mmu_idx,
bool probe, uintptr_t retaddr)
{
#ifndef CONFIG_USER_ONLY
RISCVCPU *cpu = RISCV_CPU(cs->uc, cs);
CPURISCVState *env = &cpu->env;
hwaddr pa = 0;
int prot;
bool pmp_violation = false;
int ret = TRANSLATE_FAIL;
int mode = mmu_idx;
qemu_log_mask(CPU_LOG_MMU, "%s ad %" VADDR_PRIx " rw %d mmu_idx %d\n",
__func__, address, access_type, mmu_idx);
ret = get_physical_address(env, &pa, &prot, address, access_type, mmu_idx);
if (mode == PRV_M && access_type != MMU_INST_FETCH) {
if (get_field(env->mstatus, MSTATUS_MPRV)) {
mode = get_field(env->mstatus, MSTATUS_MPP);
}
}
qemu_log_mask(CPU_LOG_MMU,
"%s address=%" VADDR_PRIx " ret %d physical " TARGET_FMT_plx
" prot %d\n", __func__, address, ret, pa, prot);
if (riscv_feature(env, RISCV_FEATURE_PMP) &&
(ret == TRANSLATE_SUCCESS) &&
!pmp_hart_has_privs(env, pa, size, 1 << access_type, mode)) {
ret = TRANSLATE_PMP_FAIL;
}
if (ret == TRANSLATE_PMP_FAIL) {
pmp_violation = true;
}
if (ret == TRANSLATE_SUCCESS) {
tlb_set_page(cs, address & TARGET_PAGE_MASK, pa & TARGET_PAGE_MASK,
prot, mmu_idx, TARGET_PAGE_SIZE);
return true;
} else if (probe) {
return false;
} else {
raise_mmu_exception(env, address, access_type, pmp_violation);
riscv_raise_exception(env, cs->exception_index, retaddr);
}
#else
switch (access_type) {
case MMU_INST_FETCH:
cs->exception_index = RISCV_EXCP_INST_PAGE_FAULT;
break;
case MMU_DATA_LOAD:
cs->exception_index = RISCV_EXCP_LOAD_PAGE_FAULT;
break;
case MMU_DATA_STORE:
cs->exception_index = RISCV_EXCP_STORE_PAGE_FAULT;
break;
}
cpu_loop_exit_restore(cs, retaddr);
#endif
}
/*
* Handle Traps
*
* Adapted from Spike's processor_t::take_trap.
*
*/
void riscv_cpu_do_interrupt(CPUState *cs)
{
#if !defined(CONFIG_USER_ONLY)
RISCVCPU *cpu = RISCV_CPU(cs->uc, cs);
CPURISCVState *env = &cpu->env;
/* cs->exception is 32-bits wide unlike mcause which is XLEN-bits wide
* so we mask off the MSB and separate into trap type and cause.
*/
bool async = !!(cs->exception_index & RISCV_EXCP_INT_FLAG);
target_ulong cause = cs->exception_index & RISCV_EXCP_INT_MASK;
target_ulong deleg = async ? env->mideleg : env->medeleg;
target_ulong tval = 0;
static const int ecall_cause_map[] = {
[PRV_U] = RISCV_EXCP_U_ECALL,
[PRV_S] = RISCV_EXCP_S_ECALL,
[PRV_H] = RISCV_EXCP_VS_ECALL,
[PRV_M] = RISCV_EXCP_M_ECALL
};
if (!async) {
/* set tval to badaddr for traps with address information */
switch (cause) {
case RISCV_EXCP_INST_GUEST_PAGE_FAULT:
case RISCV_EXCP_LOAD_GUEST_ACCESS_FAULT:
case RISCV_EXCP_STORE_GUEST_AMO_ACCESS_FAULT:
case RISCV_EXCP_INST_ADDR_MIS:
case RISCV_EXCP_INST_ACCESS_FAULT:
case RISCV_EXCP_LOAD_ADDR_MIS:
case RISCV_EXCP_STORE_AMO_ADDR_MIS:
case RISCV_EXCP_LOAD_ACCESS_FAULT:
case RISCV_EXCP_STORE_AMO_ACCESS_FAULT:
case RISCV_EXCP_INST_PAGE_FAULT:
case RISCV_EXCP_LOAD_PAGE_FAULT:
case RISCV_EXCP_STORE_PAGE_FAULT:
tval = env->badaddr;
break;
default:
break;
}
/* ecall is dispatched as one cause so translate based on mode */
if (cause == RISCV_EXCP_U_ECALL) {
assert(env->priv <= 3);
cause = ecall_cause_map[env->priv];
}
}
if (RISCV_DEBUG_INTERRUPT) {
qemu_log_mask(LOG_TRACE, "core " TARGET_FMT_ld ": %s %s, "
"epc 0x" TARGET_FMT_lx ": tval 0x" TARGET_FMT_lx "\n",
env->mhartid, async ? "intr" : "trap",
(async ? riscv_intr_names : riscv_excp_names)[cause],
env->pc, tval);
}
if (env->priv <= PRV_S &&
cause < TARGET_LONG_BITS && ((deleg >> cause) & 1)) {
/* handle the trap in S-mode */
target_ulong s = env->mstatus;
s = set_field(s, MSTATUS_SPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
get_field(s, MSTATUS_SIE) : get_field(s, MSTATUS_UIE << env->priv));
s = set_field(s, MSTATUS_SPP, env->priv);
s = set_field(s, MSTATUS_SIE, 0);
env->mstatus = s;
env->scause = cause | ((target_ulong)async << (TARGET_LONG_BITS - 1));
env->sepc = env->pc;
env->sbadaddr = tval;
env->pc = (env->stvec >> 2 << 2) +
((async && (env->stvec & 3) == 1) ? cause * 4 : 0);
riscv_cpu_set_mode(env, PRV_S);
} else {
/* handle the trap in M-mode */
target_ulong s = env->mstatus;
s = set_field(s, MSTATUS_MPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
get_field(s, MSTATUS_MIE) : get_field(s, MSTATUS_UIE << env->priv));
s = set_field(s, MSTATUS_MPP, env->priv);
s = set_field(s, MSTATUS_MIE, 0);
env->mstatus = s;
env->mcause = cause | ~(((target_ulong)-1) >> async);
env->mepc = env->pc;
env->mbadaddr = tval;
env->pc = (env->mtvec >> 2 << 2) +
((async && (env->mtvec & 3) == 1) ? cause * 4 : 0);
riscv_cpu_set_mode(env, PRV_M);
}
/* NOTE: it is not necessary to yield load reservations here. It is only
* necessary for an SC from "another hart" to cause a load reservation
* to be yielded. Refer to the memory consistency model section of the
* RISC-V ISA Specification.
*/
#endif
cs->exception_index = EXCP_NONE; /* mark handled to qemu */
}