target/riscv/op_helper.c - third_party/qemu - Git at Google

 /*
  * RISC-V Emulation Helpers for QEMU.
  *
  * Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
  * Copyright (c) 2017-2018 SiFive, Inc.
  * Copyright (c) 2022      VRULL GmbH
  *
  * 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 "cpu.h"
 #include "internals.h"
 #include "exec/exec-all.h"
 #include "exec/cpu_ldst.h"
 #include "exec/helper-proto.h"

 /* Exceptions processing helpers */
 G_NORETURN void riscv_raise_exception(CPURISCVState *env,
                                       uint32_t exception, uintptr_t pc)
 {
     CPUState *cs = env_cpu(env);
     cs->exception_index = exception;
     cpu_loop_exit_restore(cs, pc);
 }

 void helper_raise_exception(CPURISCVState *env, uint32_t exception)
 {
     riscv_raise_exception(env, exception, 0);
 }

 target_ulong helper_csrr(CPURISCVState *env, int csr)
 {
     /*
      * The seed CSR must be accessed with a read-write instruction. A
      * read-only instruction such as CSRRS/CSRRC with rs1=x0 or CSRRSI/
      * CSRRCI with uimm=0 will raise an illegal instruction exception.
      */
     if (csr == CSR_SEED) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     }

     target_ulong val = 0;
     RISCVException ret = riscv_csrrw(env, csr, &val, 0, 0);

     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }
     return val;
 }

 void helper_csrw(CPURISCVState *env, int csr, target_ulong src)
 {
     target_ulong mask = env->xl == MXL_RV32 ? UINT32_MAX : (target_ulong)-1;
     RISCVException ret = riscv_csrrw(env, csr, NULL, src, mask);

     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }
 }

 target_ulong helper_csrrw(CPURISCVState *env, int csr,
                           target_ulong src, target_ulong write_mask)
 {
     target_ulong val = 0;
     RISCVException ret = riscv_csrrw(env, csr, &val, src, write_mask);

     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }
     return val;
 }

 target_ulong helper_csrr_i128(CPURISCVState *env, int csr)
 {
     Int128 rv = int128_zero();
     RISCVException ret = riscv_csrrw_i128(env, csr, &rv,
                                           int128_zero(),
                                           int128_zero());

     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }

     env->retxh = int128_gethi(rv);
     return int128_getlo(rv);
 }

 void helper_csrw_i128(CPURISCVState *env, int csr,
                       target_ulong srcl, target_ulong srch)
 {
     RISCVException ret = riscv_csrrw_i128(env, csr, NULL,
                                           int128_make128(srcl, srch),
                                           UINT128_MAX);

     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }
 }

 target_ulong helper_csrrw_i128(CPURISCVState *env, int csr,
                        target_ulong srcl, target_ulong srch,
                        target_ulong maskl, target_ulong maskh)
 {
     Int128 rv = int128_zero();
     RISCVException ret = riscv_csrrw_i128(env, csr, &rv,
                                           int128_make128(srcl, srch),
                                           int128_make128(maskl, maskh));

     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
     }

     env->retxh = int128_gethi(rv);
     return int128_getlo(rv);
 }


 /*
  * check_zicbo_envcfg
  *
  * Raise virtual exceptions and illegal instruction exceptions for
  * Zicbo[mz] instructions based on the settings of [mhs]envcfg as
  * specified in section 2.5.1 of the CMO specification.
  */
 static void check_zicbo_envcfg(CPURISCVState *env, target_ulong envbits,
                                 uintptr_t ra)
 {
 #ifndef CONFIG_USER_ONLY
     if ((env->priv < PRV_M) && !get_field(env->menvcfg, envbits)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra);
     }

     if (env->virt_enabled &&
         (((env->priv <= PRV_S) && !get_field(env->henvcfg, envbits)) ||
          ((env->priv < PRV_S) && !get_field(env->senvcfg, envbits)))) {
         riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, ra);
     }

     if ((env->priv < PRV_S) && !get_field(env->senvcfg, envbits)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra);
     }
 #endif
 }

 void helper_cbo_zero(CPURISCVState *env, target_ulong address)
 {
     RISCVCPU *cpu = env_archcpu(env);
     uint16_t cbozlen = cpu->cfg.cboz_blocksize;
     int mmu_idx = riscv_env_mmu_index(env, false);
     uintptr_t ra = GETPC();
     void *mem;

     check_zicbo_envcfg(env, MENVCFG_CBZE, ra);

     /* Mask off low-bits to align-down to the cache-block. */
     address &= ~(cbozlen - 1);

     /*
      * cbo.zero requires MMU_DATA_STORE access. Do a probe_write()
      * to raise any exceptions, including PMP.
      */
     mem = probe_write(env, address, cbozlen, mmu_idx, ra);

     if (likely(mem)) {
         memset(mem, 0, cbozlen);
     } else {
         /*
          * This means that we're dealing with an I/O page. Section 4.2
          * of cmobase v1.0.1 says:
          *
          * "Cache-block zero instructions store zeros independently
          * of whether data from the underlying memory locations are
          * cacheable."
          *
          * Write zeros in address + cbozlen regardless of not being
          * a RAM page.
          */
         for (int i = 0; i < cbozlen; i++) {
             cpu_stb_mmuidx_ra(env, address + i, 0, mmu_idx, ra);
         }
     }
 }

 /*
  * check_zicbom_access
  *
  * Check access permissions (LOAD, STORE or FETCH as specified in
  * section 2.5.2 of the CMO specification) for Zicbom, raising
  * either store page-fault (non-virtualized) or store guest-page
  * fault (virtualized).
  */
 static void check_zicbom_access(CPURISCVState *env,
                                 target_ulong address,
                                 uintptr_t ra)
 {
     RISCVCPU *cpu = env_archcpu(env);
     int mmu_idx = riscv_env_mmu_index(env, false);
     uint16_t cbomlen = cpu->cfg.cbom_blocksize;
     void *phost;
     int ret;

     /* Mask off low-bits to align-down to the cache-block. */
     address &= ~(cbomlen - 1);

     /*
      * Section 2.5.2 of cmobase v1.0.1:
      *
      * "A cache-block management instruction is permitted to
      * access the specified cache block whenever a load instruction
      * or store instruction is permitted to access the corresponding
      * physical addresses. If neither a load instruction nor store
      * instruction is permitted to access the physical addresses,
      * but an instruction fetch is permitted to access the physical
      * addresses, whether a cache-block management instruction is
      * permitted to access the cache block is UNSPECIFIED."
      */
     ret = probe_access_flags(env, address, cbomlen, MMU_DATA_LOAD,
                              mmu_idx, true, &phost, ra);
     if (ret != TLB_INVALID_MASK) {
         /* Success: readable */
         return;
     }

     /*
      * Since not readable, must be writable. On failure, store
      * fault/store guest amo fault will be raised by
      * riscv_cpu_tlb_fill(). PMP exceptions will be caught
      * there as well.
      */
     probe_write(env, address, cbomlen, mmu_idx, ra);
 }

 void helper_cbo_clean_flush(CPURISCVState *env, target_ulong address)
 {
     uintptr_t ra = GETPC();
     check_zicbo_envcfg(env, MENVCFG_CBCFE, ra);
     check_zicbom_access(env, address, ra);

     /* We don't emulate the cache-hierarchy, so we're done. */
 }

 void helper_cbo_inval(CPURISCVState *env, target_ulong address)
 {
     uintptr_t ra = GETPC();
     check_zicbo_envcfg(env, MENVCFG_CBIE, ra);
     check_zicbom_access(env, address, ra);

     /* We don't emulate the cache-hierarchy, so we're done. */
 }

 #ifndef CONFIG_USER_ONLY

 target_ulong helper_sret(CPURISCVState *env)
 {
     uint64_t mstatus;
     target_ulong prev_priv, prev_virt;

     if (!(env->priv >= PRV_S)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     }

     target_ulong retpc = env->sepc;
     if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
         riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
     }

     if (get_field(env->mstatus, MSTATUS_TSR) && !(env->priv >= PRV_M)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     }

     if (env->virt_enabled && get_field(env->hstatus, HSTATUS_VTSR)) {
         riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
     }

     mstatus = env->mstatus;
     prev_priv = get_field(mstatus, MSTATUS_SPP);
     mstatus = set_field(mstatus, MSTATUS_SIE,
                         get_field(mstatus, MSTATUS_SPIE));
     mstatus = set_field(mstatus, MSTATUS_SPIE, 1);
     mstatus = set_field(mstatus, MSTATUS_SPP, PRV_U);
     if (env->priv_ver >= PRIV_VERSION_1_12_0) {
         mstatus = set_field(mstatus, MSTATUS_MPRV, 0);
     }
     env->mstatus = mstatus;

     if (riscv_has_ext(env, RVH) && !env->virt_enabled) {
         /* We support Hypervisor extensions and virtulisation is disabled */
         target_ulong hstatus = env->hstatus;

         prev_virt = get_field(hstatus, HSTATUS_SPV);

         hstatus = set_field(hstatus, HSTATUS_SPV, 0);

         env->hstatus = hstatus;

         if (prev_virt) {
             riscv_cpu_swap_hypervisor_regs(env);
         }

         riscv_cpu_set_virt_enabled(env, prev_virt);
     }

     riscv_cpu_set_mode(env, prev_priv);

     return retpc;
 }

 target_ulong helper_mret(CPURISCVState *env)
 {
     if (!(env->priv >= PRV_M)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     }

     target_ulong retpc = env->mepc;
     if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
         riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
     }

     uint64_t mstatus = env->mstatus;
     target_ulong prev_priv = get_field(mstatus, MSTATUS_MPP);

     if (riscv_cpu_cfg(env)->pmp &&
         !pmp_get_num_rules(env) && (prev_priv != PRV_M)) {
         riscv_raise_exception(env, RISCV_EXCP_INST_ACCESS_FAULT, GETPC());
     }

     target_ulong prev_virt = get_field(env->mstatus, MSTATUS_MPV) &&
                              (prev_priv != PRV_M);
     mstatus = set_field(mstatus, MSTATUS_MIE,
                         get_field(mstatus, MSTATUS_MPIE));
     mstatus = set_field(mstatus, MSTATUS_MPIE, 1);
     mstatus = set_field(mstatus, MSTATUS_MPP,
                         riscv_has_ext(env, RVU) ? PRV_U : PRV_M);
     mstatus = set_field(mstatus, MSTATUS_MPV, 0);
     if ((env->priv_ver >= PRIV_VERSION_1_12_0) && (prev_priv != PRV_M)) {
         mstatus = set_field(mstatus, MSTATUS_MPRV, 0);
     }
     env->mstatus = mstatus;
     riscv_cpu_set_mode(env, prev_priv);

     if (riscv_has_ext(env, RVH)) {
         if (prev_virt) {
             riscv_cpu_swap_hypervisor_regs(env);
         }

         riscv_cpu_set_virt_enabled(env, prev_virt);
     }

     return retpc;
 }

 void helper_wfi(CPURISCVState *env)
 {
     CPUState *cs = env_cpu(env);
     bool rvs = riscv_has_ext(env, RVS);
     bool prv_u = env->priv == PRV_U;
     bool prv_s = env->priv == PRV_S;

     if (((prv_s || (!rvs && prv_u)) && get_field(env->mstatus, MSTATUS_TW)) ||
         (rvs && prv_u && !env->virt_enabled)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     } else if (env->virt_enabled &&
                (prv_u || (prv_s && get_field(env->hstatus, HSTATUS_VTW)))) {
         riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
     } else {
         cs->halted = 1;
         cs->exception_index = EXCP_HLT;
         cpu_loop_exit(cs);
     }
 }

 void helper_tlb_flush(CPURISCVState *env)
 {
     CPUState *cs = env_cpu(env);
     if (!env->virt_enabled &&
         (env->priv == PRV_U ||
          (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_TVM)))) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     } else if (env->virt_enabled &&
                (env->priv == PRV_U || get_field(env->hstatus, HSTATUS_VTVM))) {
         riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
     } else {
         tlb_flush(cs);
     }
 }

 void helper_tlb_flush_all(CPURISCVState *env)
 {
     CPUState *cs = env_cpu(env);
     tlb_flush_all_cpus_synced(cs);
 }

 void helper_hyp_tlb_flush(CPURISCVState *env)
 {
     CPUState *cs = env_cpu(env);

     if (env->virt_enabled) {
         riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
     }

     if (env->priv == PRV_M ||
         (env->priv == PRV_S && !env->virt_enabled)) {
         tlb_flush(cs);
         return;
     }

     riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
 }

 void helper_hyp_gvma_tlb_flush(CPURISCVState *env)
 {
     if (env->priv == PRV_S && !env->virt_enabled &&
         get_field(env->mstatus, MSTATUS_TVM)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     }

     helper_hyp_tlb_flush(env);
 }

 static int check_access_hlsv(CPURISCVState *env, bool x, uintptr_t ra)
 {
     if (env->priv == PRV_M) {
         /* always allowed */
     } else if (env->virt_enabled) {
         riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, ra);
     } else if (env->priv == PRV_U && !get_field(env->hstatus, HSTATUS_HU)) {
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra);
     }

     int mode = get_field(env->hstatus, HSTATUS_SPVP);
     if (!x && mode == PRV_S && get_field(env->vsstatus, MSTATUS_SUM)) {
         mode = MMUIdx_S_SUM;
     }
     return mode | MMU_2STAGE_BIT;
 }

 target_ulong helper_hyp_hlv_bu(CPURISCVState *env, target_ulong addr)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);

     return cpu_ldb_mmu(env, addr, oi, ra);
 }

 target_ulong helper_hyp_hlv_hu(CPURISCVState *env, target_ulong addr)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUW, mmu_idx);

     return cpu_ldw_mmu(env, addr, oi, ra);
 }

 target_ulong helper_hyp_hlv_wu(CPURISCVState *env, target_ulong addr)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUL, mmu_idx);

     return cpu_ldl_mmu(env, addr, oi, ra);
 }

 target_ulong helper_hyp_hlv_d(CPURISCVState *env, target_ulong addr)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUQ, mmu_idx);

     return cpu_ldq_mmu(env, addr, oi, ra);
 }

 void helper_hyp_hsv_b(CPURISCVState *env, target_ulong addr, target_ulong val)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);

     cpu_stb_mmu(env, addr, val, oi, ra);
 }

 void helper_hyp_hsv_h(CPURISCVState *env, target_ulong addr, target_ulong val)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUW, mmu_idx);

     cpu_stw_mmu(env, addr, val, oi, ra);
 }

 void helper_hyp_hsv_w(CPURISCVState *env, target_ulong addr, target_ulong val)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUL, mmu_idx);

     cpu_stl_mmu(env, addr, val, oi, ra);
 }

 void helper_hyp_hsv_d(CPURISCVState *env, target_ulong addr, target_ulong val)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, false, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUQ, mmu_idx);

     cpu_stq_mmu(env, addr, val, oi, ra);
 }

 /*
  * TODO: These implementations are not quite correct.  They perform the
  * access using execute permission just fine, but the final PMP check
  * is supposed to have read permission as well.  Without replicating
  * a fair fraction of cputlb.c, fixing this requires adding new mmu_idx
  * which would imply that exact check in tlb_fill.
  */
 target_ulong helper_hyp_hlvx_hu(CPURISCVState *env, target_ulong addr)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, true, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUW, mmu_idx);

     return cpu_ldw_code_mmu(env, addr, oi, GETPC());
 }

 target_ulong helper_hyp_hlvx_wu(CPURISCVState *env, target_ulong addr)
 {
     uintptr_t ra = GETPC();
     int mmu_idx = check_access_hlsv(env, true, ra);
     MemOpIdx oi = make_memop_idx(MO_TEUL, mmu_idx);

     return cpu_ldl_code_mmu(env, addr, oi, ra);
 }

 #endif /* !CONFIG_USER_ONLY */
	/*
	* RISC-V Emulation Helpers for QEMU.
	*
	* Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
	* Copyright (c) 2017-2018 SiFive, Inc.
	* Copyright (c) 2022 VRULL GmbH
	*
	* 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 "cpu.h"
	#include "internals.h"
	#include "exec/exec-all.h"
	#include "exec/cpu_ldst.h"
	#include "exec/helper-proto.h"

	/* Exceptions processing helpers */
	G_NORETURN void riscv_raise_exception(CPURISCVState *env,
	uint32_t exception, uintptr_t pc)
	{
	CPUState *cs = env_cpu(env);
	cs->exception_index = exception;
	cpu_loop_exit_restore(cs, pc);
	}

	void helper_raise_exception(CPURISCVState *env, uint32_t exception)
	{
	riscv_raise_exception(env, exception, 0);
	}

	target_ulong helper_csrr(CPURISCVState *env, int csr)
	{
	/*
	* The seed CSR must be accessed with a read-write instruction. A
	* read-only instruction such as CSRRS/CSRRC with rs1=x0 or CSRRSI/
	* CSRRCI with uimm=0 will raise an illegal instruction exception.
	*/
	if (csr == CSR_SEED) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	}

	target_ulong val = 0;
	RISCVException ret = riscv_csrrw(env, csr, &val, 0, 0);

	if (ret != RISCV_EXCP_NONE) {
	riscv_raise_exception(env, ret, GETPC());
	}
	return val;
	}

	void helper_csrw(CPURISCVState *env, int csr, target_ulong src)
	{
	target_ulong mask = env->xl == MXL_RV32 ? UINT32_MAX : (target_ulong)-1;
	RISCVException ret = riscv_csrrw(env, csr, NULL, src, mask);

	if (ret != RISCV_EXCP_NONE) {
	riscv_raise_exception(env, ret, GETPC());
	}
	}

	target_ulong helper_csrrw(CPURISCVState *env, int csr,
	target_ulong src, target_ulong write_mask)
	{
	target_ulong val = 0;
	RISCVException ret = riscv_csrrw(env, csr, &val, src, write_mask);

	if (ret != RISCV_EXCP_NONE) {
	riscv_raise_exception(env, ret, GETPC());
	}
	return val;
	}

	target_ulong helper_csrr_i128(CPURISCVState *env, int csr)
	{
	Int128 rv = int128_zero();
	RISCVException ret = riscv_csrrw_i128(env, csr, &rv,
	int128_zero(),
	int128_zero());

	if (ret != RISCV_EXCP_NONE) {
	riscv_raise_exception(env, ret, GETPC());
	}

	env->retxh = int128_gethi(rv);
	return int128_getlo(rv);
	}

	void helper_csrw_i128(CPURISCVState *env, int csr,
	target_ulong srcl, target_ulong srch)
	{
	RISCVException ret = riscv_csrrw_i128(env, csr, NULL,
	int128_make128(srcl, srch),
	UINT128_MAX);

	if (ret != RISCV_EXCP_NONE) {
	riscv_raise_exception(env, ret, GETPC());
	}
	}

	target_ulong helper_csrrw_i128(CPURISCVState *env, int csr,
	target_ulong srcl, target_ulong srch,
	target_ulong maskl, target_ulong maskh)
	{
	Int128 rv = int128_zero();
	RISCVException ret = riscv_csrrw_i128(env, csr, &rv,
	int128_make128(srcl, srch),
	int128_make128(maskl, maskh));

	if (ret != RISCV_EXCP_NONE) {
	riscv_raise_exception(env, ret, GETPC());
	}

	env->retxh = int128_gethi(rv);
	return int128_getlo(rv);
	}


	/*
	* check_zicbo_envcfg
	*
	* Raise virtual exceptions and illegal instruction exceptions for
	* Zicbo[mz] instructions based on the settings of [mhs]envcfg as
	* specified in section 2.5.1 of the CMO specification.
	*/
	static void check_zicbo_envcfg(CPURISCVState *env, target_ulong envbits,
	uintptr_t ra)
	{
	#ifndef CONFIG_USER_ONLY
	if ((env->priv < PRV_M) && !get_field(env->menvcfg, envbits)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra);
	}

	if (env->virt_enabled &&
	(((env->priv <= PRV_S) && !get_field(env->henvcfg, envbits)) \|\|
	((env->priv < PRV_S) && !get_field(env->senvcfg, envbits)))) {
	riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, ra);
	}

	if ((env->priv < PRV_S) && !get_field(env->senvcfg, envbits)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra);
	}
	#endif
	}

	void helper_cbo_zero(CPURISCVState *env, target_ulong address)
	{
	RISCVCPU *cpu = env_archcpu(env);
	uint16_t cbozlen = cpu->cfg.cboz_blocksize;
	int mmu_idx = riscv_env_mmu_index(env, false);
	uintptr_t ra = GETPC();
	void *mem;

	check_zicbo_envcfg(env, MENVCFG_CBZE, ra);

	/* Mask off low-bits to align-down to the cache-block. */
	address &= ~(cbozlen - 1);

	/*
	* cbo.zero requires MMU_DATA_STORE access. Do a probe_write()
	* to raise any exceptions, including PMP.
	*/
	mem = probe_write(env, address, cbozlen, mmu_idx, ra);

	if (likely(mem)) {
	memset(mem, 0, cbozlen);
	} else {
	/*
	* This means that we're dealing with an I/O page. Section 4.2
	* of cmobase v1.0.1 says:
	*
	* "Cache-block zero instructions store zeros independently
	* of whether data from the underlying memory locations are
	* cacheable."
	*
	* Write zeros in address + cbozlen regardless of not being
	* a RAM page.
	*/
	for (int i = 0; i < cbozlen; i++) {
	cpu_stb_mmuidx_ra(env, address + i, 0, mmu_idx, ra);
	}
	}
	}

	/*
	* check_zicbom_access
	*
	* Check access permissions (LOAD, STORE or FETCH as specified in
	* section 2.5.2 of the CMO specification) for Zicbom, raising
	* either store page-fault (non-virtualized) or store guest-page
	* fault (virtualized).
	*/
	static void check_zicbom_access(CPURISCVState *env,
	target_ulong address,
	uintptr_t ra)
	{
	RISCVCPU *cpu = env_archcpu(env);
	int mmu_idx = riscv_env_mmu_index(env, false);
	uint16_t cbomlen = cpu->cfg.cbom_blocksize;
	void *phost;
	int ret;

	/* Mask off low-bits to align-down to the cache-block. */
	address &= ~(cbomlen - 1);

	/*
	* Section 2.5.2 of cmobase v1.0.1:
	*
	* "A cache-block management instruction is permitted to
	* access the specified cache block whenever a load instruction
	* or store instruction is permitted to access the corresponding
	* physical addresses. If neither a load instruction nor store
	* instruction is permitted to access the physical addresses,
	* but an instruction fetch is permitted to access the physical
	* addresses, whether a cache-block management instruction is
	* permitted to access the cache block is UNSPECIFIED."
	*/
	ret = probe_access_flags(env, address, cbomlen, MMU_DATA_LOAD,
	mmu_idx, true, &phost, ra);
	if (ret != TLB_INVALID_MASK) {
	/* Success: readable */
	return;
	}

	/*
	* Since not readable, must be writable. On failure, store
	* fault/store guest amo fault will be raised by
	* riscv_cpu_tlb_fill(). PMP exceptions will be caught
	* there as well.
	*/
	probe_write(env, address, cbomlen, mmu_idx, ra);
	}

	void helper_cbo_clean_flush(CPURISCVState *env, target_ulong address)
	{
	uintptr_t ra = GETPC();
	check_zicbo_envcfg(env, MENVCFG_CBCFE, ra);
	check_zicbom_access(env, address, ra);

	/* We don't emulate the cache-hierarchy, so we're done. */
	}

	void helper_cbo_inval(CPURISCVState *env, target_ulong address)
	{
	uintptr_t ra = GETPC();
	check_zicbo_envcfg(env, MENVCFG_CBIE, ra);
	check_zicbom_access(env, address, ra);

	/* We don't emulate the cache-hierarchy, so we're done. */
	}

	#ifndef CONFIG_USER_ONLY

	target_ulong helper_sret(CPURISCVState *env)
	{
	uint64_t mstatus;
	target_ulong prev_priv, prev_virt;

	if (!(env->priv >= PRV_S)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	}

	target_ulong retpc = env->sepc;
	if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
	riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
	}

	if (get_field(env->mstatus, MSTATUS_TSR) && !(env->priv >= PRV_M)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	}

	if (env->virt_enabled && get_field(env->hstatus, HSTATUS_VTSR)) {
	riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
	}

	mstatus = env->mstatus;
	prev_priv = get_field(mstatus, MSTATUS_SPP);
	mstatus = set_field(mstatus, MSTATUS_SIE,
	get_field(mstatus, MSTATUS_SPIE));
	mstatus = set_field(mstatus, MSTATUS_SPIE, 1);
	mstatus = set_field(mstatus, MSTATUS_SPP, PRV_U);
	if (env->priv_ver >= PRIV_VERSION_1_12_0) {
	mstatus = set_field(mstatus, MSTATUS_MPRV, 0);
	}
	env->mstatus = mstatus;

	if (riscv_has_ext(env, RVH) && !env->virt_enabled) {
	/* We support Hypervisor extensions and virtulisation is disabled */
	target_ulong hstatus = env->hstatus;

	prev_virt = get_field(hstatus, HSTATUS_SPV);

	hstatus = set_field(hstatus, HSTATUS_SPV, 0);

	env->hstatus = hstatus;

	if (prev_virt) {
	riscv_cpu_swap_hypervisor_regs(env);
	}

	riscv_cpu_set_virt_enabled(env, prev_virt);
	}

	riscv_cpu_set_mode(env, prev_priv);

	return retpc;
	}

	target_ulong helper_mret(CPURISCVState *env)
	{
	if (!(env->priv >= PRV_M)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	}

	target_ulong retpc = env->mepc;
	if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
	riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
	}

	uint64_t mstatus = env->mstatus;
	target_ulong prev_priv = get_field(mstatus, MSTATUS_MPP);

	if (riscv_cpu_cfg(env)->pmp &&
	!pmp_get_num_rules(env) && (prev_priv != PRV_M)) {
	riscv_raise_exception(env, RISCV_EXCP_INST_ACCESS_FAULT, GETPC());
	}

	target_ulong prev_virt = get_field(env->mstatus, MSTATUS_MPV) &&
	(prev_priv != PRV_M);
	mstatus = set_field(mstatus, MSTATUS_MIE,
	get_field(mstatus, MSTATUS_MPIE));
	mstatus = set_field(mstatus, MSTATUS_MPIE, 1);
	mstatus = set_field(mstatus, MSTATUS_MPP,
	riscv_has_ext(env, RVU) ? PRV_U : PRV_M);
	mstatus = set_field(mstatus, MSTATUS_MPV, 0);
	if ((env->priv_ver >= PRIV_VERSION_1_12_0) && (prev_priv != PRV_M)) {
	mstatus = set_field(mstatus, MSTATUS_MPRV, 0);
	}
	env->mstatus = mstatus;
	riscv_cpu_set_mode(env, prev_priv);

	if (riscv_has_ext(env, RVH)) {
	if (prev_virt) {
	riscv_cpu_swap_hypervisor_regs(env);
	}

	riscv_cpu_set_virt_enabled(env, prev_virt);
	}

	return retpc;
	}

	void helper_wfi(CPURISCVState *env)
	{
	CPUState *cs = env_cpu(env);
	bool rvs = riscv_has_ext(env, RVS);
	bool prv_u = env->priv == PRV_U;
	bool prv_s = env->priv == PRV_S;

	if (((prv_s \|\| (!rvs && prv_u)) && get_field(env->mstatus, MSTATUS_TW)) \|\|
	(rvs && prv_u && !env->virt_enabled)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	} else if (env->virt_enabled &&
	(prv_u \|\| (prv_s && get_field(env->hstatus, HSTATUS_VTW)))) {
	riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
	} else {
	cs->halted = 1;
	cs->exception_index = EXCP_HLT;
	cpu_loop_exit(cs);
	}
	}

	void helper_tlb_flush(CPURISCVState *env)
	{
	CPUState *cs = env_cpu(env);
	if (!env->virt_enabled &&
	(env->priv == PRV_U \|\|
	(env->priv == PRV_S && get_field(env->mstatus, MSTATUS_TVM)))) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	} else if (env->virt_enabled &&
	(env->priv == PRV_U \|\| get_field(env->hstatus, HSTATUS_VTVM))) {
	riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
	} else {
	tlb_flush(cs);
	}
	}

	void helper_tlb_flush_all(CPURISCVState *env)
	{
	CPUState *cs = env_cpu(env);
	tlb_flush_all_cpus_synced(cs);
	}

	void helper_hyp_tlb_flush(CPURISCVState *env)
	{
	CPUState *cs = env_cpu(env);

	if (env->virt_enabled) {
	riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC());
	}

	if (env->priv == PRV_M \|\|
	(env->priv == PRV_S && !env->virt_enabled)) {
	tlb_flush(cs);
	return;
	}

	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	}

	void helper_hyp_gvma_tlb_flush(CPURISCVState *env)
	{
	if (env->priv == PRV_S && !env->virt_enabled &&
	get_field(env->mstatus, MSTATUS_TVM)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
	}

	helper_hyp_tlb_flush(env);
	}

	static int check_access_hlsv(CPURISCVState *env, bool x, uintptr_t ra)
	{
	if (env->priv == PRV_M) {
	/* always allowed */
	} else if (env->virt_enabled) {
	riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, ra);
	} else if (env->priv == PRV_U && !get_field(env->hstatus, HSTATUS_HU)) {
	riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra);
	}

	int mode = get_field(env->hstatus, HSTATUS_SPVP);
	if (!x && mode == PRV_S && get_field(env->vsstatus, MSTATUS_SUM)) {
	mode = MMUIdx_S_SUM;
	}
	return mode \| MMU_2STAGE_BIT;
	}

	target_ulong helper_hyp_hlv_bu(CPURISCVState *env, target_ulong addr)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);

	return cpu_ldb_mmu(env, addr, oi, ra);
	}

	target_ulong helper_hyp_hlv_hu(CPURISCVState *env, target_ulong addr)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUW, mmu_idx);

	return cpu_ldw_mmu(env, addr, oi, ra);
	}

	target_ulong helper_hyp_hlv_wu(CPURISCVState *env, target_ulong addr)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUL, mmu_idx);

	return cpu_ldl_mmu(env, addr, oi, ra);
	}

	target_ulong helper_hyp_hlv_d(CPURISCVState *env, target_ulong addr)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUQ, mmu_idx);

	return cpu_ldq_mmu(env, addr, oi, ra);
	}

	void helper_hyp_hsv_b(CPURISCVState *env, target_ulong addr, target_ulong val)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);

	cpu_stb_mmu(env, addr, val, oi, ra);
	}

	void helper_hyp_hsv_h(CPURISCVState *env, target_ulong addr, target_ulong val)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUW, mmu_idx);

	cpu_stw_mmu(env, addr, val, oi, ra);
	}

	void helper_hyp_hsv_w(CPURISCVState *env, target_ulong addr, target_ulong val)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUL, mmu_idx);

	cpu_stl_mmu(env, addr, val, oi, ra);
	}

	void helper_hyp_hsv_d(CPURISCVState *env, target_ulong addr, target_ulong val)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, false, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUQ, mmu_idx);

	cpu_stq_mmu(env, addr, val, oi, ra);
	}

	/*
	* TODO: These implementations are not quite correct. They perform the
	* access using execute permission just fine, but the final PMP check
	* is supposed to have read permission as well. Without replicating
	* a fair fraction of cputlb.c, fixing this requires adding new mmu_idx
	* which would imply that exact check in tlb_fill.
	*/
	target_ulong helper_hyp_hlvx_hu(CPURISCVState *env, target_ulong addr)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, true, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUW, mmu_idx);

	return cpu_ldw_code_mmu(env, addr, oi, GETPC());
	}

	target_ulong helper_hyp_hlvx_wu(CPURISCVState *env, target_ulong addr)
	{
	uintptr_t ra = GETPC();
	int mmu_idx = check_access_hlsv(env, true, ra);
	MemOpIdx oi = make_memop_idx(MO_TEUL, mmu_idx);

	return cpu_ldl_code_mmu(env, addr, oi, ra);
	}

	#endif /* !CONFIG_USER_ONLY */