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qemu/target/riscv/helper.c

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/*
* RISC-V emulation 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
/*
* Return RISC-V IRQ number if an interrupt should be taken, else -1.
* Used in cpu-exec.c
*
* Adapted from Spike's processor_t::take_interrupt()
*/
static int riscv_cpu_hw_interrupts_pending(CPURISCVState *env)
{
target_ulong pending_interrupts = atomic_read(&env->mip) & env->mie;
target_ulong mie = get_field(env->mstatus, MSTATUS_MIE);
target_ulong m_enabled = env->priv < PRV_M || (env->priv == PRV_M && mie);
target_ulong enabled_interrupts = pending_interrupts &
~env->mideleg & -m_enabled;
target_ulong sie = get_field(env->mstatus, MSTATUS_SIE);
target_ulong s_enabled = env->priv < PRV_S || (env->priv == PRV_S && sie);
enabled_interrupts |= pending_interrupts & env->mideleg &
-s_enabled;
if (enabled_interrupts) {
return ctz64(enabled_interrupts); /* 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);
CPURISCVState *env = &cpu->env;
int interruptno = riscv_cpu_hw_interrupts_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)
/* 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 = CPU(riscv_env_get_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 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_TABLE(pte)) { /* next level of page table */
base = ppn << PGSHIFT;
} else if ((pte & PTE_U) ? (mode == PRV_S) && !sum : !(mode == PRV_S)) {
break;
} else if (!(pte & PTE_V) || (!(pte & PTE_R) && (pte & PTE_W))) {
break;
} else if (access_type == MMU_INST_FETCH ? !(pte & PTE_X) :
access_type == MMU_DATA_LOAD ? !(pte & PTE_R) &&
!(mxr && (pte & PTE_X)) : !((pte & PTE_R) && (pte & PTE_W))) {
break;
} 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, then it can't be updated.
* if the PTE changed, then we must re-walk the page table
as the PTE is no longer valid */
MemoryRegion *mr;
hwaddr l = sizeof(target_ulong), addr1;
mr = address_space_translate(cs->as, pte_addr,
&addr1, &l, false, MEMTXATTRS_UNSPECIFIED);
if (memory_access_is_direct(mr, true)) {
target_ulong *pte_pa =
qemu_map_ram_ptr(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;
if ((pte & PTE_R)) {
*prot |= PAGE_READ;
}
if ((pte & PTE_X)) {
*prot |= PAGE_EXEC;
}
/* only add write permission on stores or if the page
is already dirty, so that we don't miss further
page table walks 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)
{
CPUState *cs = CPU(riscv_env_get_cpu(env));
int page_fault_exceptions =
(env->priv_ver >= PRIV_VERSION_1_10_0) &&
get_field(env->satp, SATP_MODE) != VM_1_10_MBARE;
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);
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_do_unaligned_access(CPUState *cs, vaddr addr,
MMUAccessType access_type, int mmu_idx,
uintptr_t retaddr)
{
RISCVCPU *cpu = RISCV_CPU(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;
do_raise_exception_err(env, cs->exception_index, retaddr);
}
/* called by qemu's softmmu to fill the qemu tlb */
void tlb_fill(CPUState *cs, target_ulong addr, int size,
MMUAccessType access_type, int mmu_idx, uintptr_t retaddr)
{
int ret;
ret = riscv_cpu_handle_mmu_fault(cs, addr, size, access_type, mmu_idx);
if (ret == TRANSLATE_FAIL) {
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
do_raise_exception_err(env, cs->exception_index, retaddr);
}
}
#endif
int riscv_cpu_handle_mmu_fault(CPUState *cs, vaddr address, int size,
int rw, int mmu_idx)
{
RISCVCPU *cpu = RISCV_CPU(cs);
CPURISCVState *env = &cpu->env;
#if !defined(CONFIG_USER_ONLY)
hwaddr pa = 0;
int prot;
#endif
int ret = TRANSLATE_FAIL;
qemu_log_mask(CPU_LOG_MMU,
"%s pc " TARGET_FMT_lx " ad %" VADDR_PRIx " rw %d mmu_idx \
%d\n", __func__, env->pc, address, rw, mmu_idx);
#if !defined(CONFIG_USER_ONLY)
ret = get_physical_address(env, &pa, &prot, address, rw, mmu_idx);
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 (!pmp_hart_has_privs(env, pa, TARGET_PAGE_SIZE, 1 << rw)) {
ret = TRANSLATE_FAIL;
}
if (ret == TRANSLATE_SUCCESS) {
tlb_set_page(cs, address & TARGET_PAGE_MASK, pa & TARGET_PAGE_MASK,
prot, mmu_idx, TARGET_PAGE_SIZE);
} else if (ret == TRANSLATE_FAIL) {
raise_mmu_exception(env, address, rw);
}
#else
switch (rw) {
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;
}
#endif
return ret;
}
/*
* 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);
CPURISCVState *env = &cpu->env;
if (RISCV_DEBUG_INTERRUPT) {
int log_cause = cs->exception_index & RISCV_EXCP_INT_MASK;
if (cs->exception_index & RISCV_EXCP_INT_FLAG) {
qemu_log_mask(LOG_TRACE, "core 0: trap %s, epc 0x" TARGET_FMT_lx,
riscv_intr_names[log_cause], env->pc);
} else {
qemu_log_mask(LOG_TRACE, "core 0: intr %s, epc 0x" TARGET_FMT_lx,
riscv_excp_names[log_cause], env->pc);
}
}
target_ulong fixed_cause = 0;
if (cs->exception_index & (RISCV_EXCP_INT_FLAG)) {
/* hacky for now. the MSB (bit 63) indicates interrupt but cs->exception
index is only 32 bits wide */
fixed_cause = cs->exception_index & RISCV_EXCP_INT_MASK;
fixed_cause |= ((target_ulong)1) << (TARGET_LONG_BITS - 1);
} else {
/* fixup User ECALL -> correct priv ECALL */
if (cs->exception_index == RISCV_EXCP_U_ECALL) {
switch (env->priv) {
case PRV_U:
fixed_cause = RISCV_EXCP_U_ECALL;
break;
case PRV_S:
fixed_cause = RISCV_EXCP_S_ECALL;
break;
case PRV_H:
fixed_cause = RISCV_EXCP_H_ECALL;
break;
case PRV_M:
fixed_cause = RISCV_EXCP_M_ECALL;
break;
}
} else {
fixed_cause = cs->exception_index;
}
}
target_ulong backup_epc = env->pc;
target_ulong bit = fixed_cause;
target_ulong deleg = env->medeleg;
int hasbadaddr =
(fixed_cause == RISCV_EXCP_INST_ADDR_MIS) ||
(fixed_cause == RISCV_EXCP_INST_ACCESS_FAULT) ||
(fixed_cause == RISCV_EXCP_LOAD_ADDR_MIS) ||
(fixed_cause == RISCV_EXCP_STORE_AMO_ADDR_MIS) ||
(fixed_cause == RISCV_EXCP_LOAD_ACCESS_FAULT) ||
(fixed_cause == RISCV_EXCP_STORE_AMO_ACCESS_FAULT) ||
(fixed_cause == RISCV_EXCP_INST_PAGE_FAULT) ||
(fixed_cause == RISCV_EXCP_LOAD_PAGE_FAULT) ||
(fixed_cause == RISCV_EXCP_STORE_PAGE_FAULT);
if (bit & ((target_ulong)1 << (TARGET_LONG_BITS - 1))) {
deleg = env->mideleg;
bit &= ~((target_ulong)1 << (TARGET_LONG_BITS - 1));
}
if (env->priv <= PRV_S && bit < 64 && ((deleg >> bit) & 1)) {
/* handle the trap in S-mode */
/* No need to check STVEC for misaligned - lower 2 bits cannot be set */
env->pc = env->stvec;
env->scause = fixed_cause;
env->sepc = backup_epc;
if (hasbadaddr) {
if (RISCV_DEBUG_INTERRUPT) {
qemu_log_mask(LOG_TRACE, "core " TARGET_FMT_ld
": badaddr 0x" TARGET_FMT_lx, env->mhartid, env->badaddr);
}
env->sbadaddr = env->badaddr;
} else {
/* otherwise we must clear sbadaddr/stval
* todo: support populating stval on illegal instructions */
env->sbadaddr = 0;
}
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);
csr_write_helper(env, s, CSR_MSTATUS);
riscv_set_mode(env, PRV_S);
} else {
/* No need to check MTVEC for misaligned - lower 2 bits cannot be set */
env->pc = env->mtvec;
env->mepc = backup_epc;
env->mcause = fixed_cause;
if (hasbadaddr) {
if (RISCV_DEBUG_INTERRUPT) {
qemu_log_mask(LOG_TRACE, "core " TARGET_FMT_ld
": badaddr 0x" TARGET_FMT_lx, env->mhartid, env->badaddr);
}
env->mbadaddr = env->badaddr;
} else {
/* otherwise we must clear mbadaddr/mtval
* todo: support populating mtval on illegal instructions */
env->mbadaddr = 0;
}
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);
csr_write_helper(env, s, CSR_MSTATUS);
riscv_set_mode(env, PRV_M);
}
/* TODO yield load reservation */
#endif
cs->exception_index = EXCP_NONE; /* mark handled to qemu */
}
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