xref: /openbmc/qemu/target/riscv/op_helper.c (revision b0240336)
1 /*
2  * RISC-V Emulation Helpers for QEMU.
3  *
4  * Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
5  * Copyright (c) 2017-2018 SiFive, Inc.
6  *
7  * This program is free software; you can redistribute it and/or modify it
8  * under the terms and conditions of the GNU General Public License,
9  * version 2 or later, as published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
14  * more details.
15  *
16  * You should have received a copy of the GNU General Public License along with
17  * this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19 
20 #include "qemu/osdep.h"
21 #include "qemu/log.h"
22 #include "cpu.h"
23 #include "qemu/main-loop.h"
24 #include "exec/exec-all.h"
25 #include "exec/helper-proto.h"
26 
27 #ifndef CONFIG_USER_ONLY
28 
29 #if defined(TARGET_RISCV32)
30 static const char valid_vm_1_09[16] = {
31     [VM_1_09_MBARE] = 1,
32     [VM_1_09_SV32] = 1,
33 };
34 static const char valid_vm_1_10[16] = {
35     [VM_1_10_MBARE] = 1,
36     [VM_1_10_SV32] = 1
37 };
38 #elif defined(TARGET_RISCV64)
39 static const char valid_vm_1_09[16] = {
40     [VM_1_09_MBARE] = 1,
41     [VM_1_09_SV39] = 1,
42     [VM_1_09_SV48] = 1,
43 };
44 static const char valid_vm_1_10[16] = {
45     [VM_1_10_MBARE] = 1,
46     [VM_1_10_SV39] = 1,
47     [VM_1_10_SV48] = 1,
48     [VM_1_10_SV57] = 1
49 };
50 #endif
51 
52 static int validate_vm(CPURISCVState *env, target_ulong vm)
53 {
54     return (env->priv_ver >= PRIV_VERSION_1_10_0) ?
55         valid_vm_1_10[vm & 0xf] : valid_vm_1_09[vm & 0xf];
56 }
57 
58 #endif
59 
60 /* Exceptions processing helpers */
61 void QEMU_NORETURN do_raise_exception_err(CPURISCVState *env,
62                                           uint32_t exception, uintptr_t pc)
63 {
64     CPUState *cs = CPU(riscv_env_get_cpu(env));
65     qemu_log_mask(CPU_LOG_INT, "%s: %d\n", __func__, exception);
66     cs->exception_index = exception;
67     cpu_loop_exit_restore(cs, pc);
68 }
69 
70 void helper_raise_exception(CPURISCVState *env, uint32_t exception)
71 {
72     do_raise_exception_err(env, exception, 0);
73 }
74 
75 static void validate_mstatus_fs(CPURISCVState *env, uintptr_t ra)
76 {
77 #ifndef CONFIG_USER_ONLY
78     if (!(env->mstatus & MSTATUS_FS)) {
79         do_raise_exception_err(env, RISCV_EXCP_ILLEGAL_INST, ra);
80     }
81 #endif
82 }
83 
84 /*
85  * Handle writes to CSRs and any resulting special behavior
86  *
87  * Adapted from Spike's processor_t::set_csr
88  */
89 void csr_write_helper(CPURISCVState *env, target_ulong val_to_write,
90         target_ulong csrno)
91 {
92 #ifndef CONFIG_USER_ONLY
93     uint64_t delegable_ints = MIP_SSIP | MIP_STIP | MIP_SEIP | (1 << IRQ_X_COP);
94     uint64_t all_ints = delegable_ints | MIP_MSIP | MIP_MTIP;
95 #endif
96 
97     switch (csrno) {
98     case CSR_FFLAGS:
99         validate_mstatus_fs(env, GETPC());
100         cpu_riscv_set_fflags(env, val_to_write & (FSR_AEXC >> FSR_AEXC_SHIFT));
101         break;
102     case CSR_FRM:
103         validate_mstatus_fs(env, GETPC());
104         env->frm = val_to_write & (FSR_RD >> FSR_RD_SHIFT);
105         break;
106     case CSR_FCSR:
107         validate_mstatus_fs(env, GETPC());
108         env->frm = (val_to_write & FSR_RD) >> FSR_RD_SHIFT;
109         cpu_riscv_set_fflags(env, (val_to_write & FSR_AEXC) >> FSR_AEXC_SHIFT);
110         break;
111 #ifndef CONFIG_USER_ONLY
112     case CSR_MSTATUS: {
113         target_ulong mstatus = env->mstatus;
114         target_ulong mask = 0;
115         target_ulong mpp = get_field(val_to_write, MSTATUS_MPP);
116 
117         /* flush tlb on mstatus fields that affect VM */
118         if (env->priv_ver <= PRIV_VERSION_1_09_1) {
119             if ((val_to_write ^ mstatus) & (MSTATUS_MXR | MSTATUS_MPP |
120                     MSTATUS_MPRV | MSTATUS_SUM | MSTATUS_VM)) {
121                 helper_tlb_flush(env);
122             }
123             mask = MSTATUS_SIE | MSTATUS_SPIE | MSTATUS_MIE | MSTATUS_MPIE |
124                 MSTATUS_SPP | MSTATUS_FS | MSTATUS_MPRV | MSTATUS_SUM |
125                 MSTATUS_MPP | MSTATUS_MXR |
126                 (validate_vm(env, get_field(val_to_write, MSTATUS_VM)) ?
127                     MSTATUS_VM : 0);
128         }
129         if (env->priv_ver >= PRIV_VERSION_1_10_0) {
130             if ((val_to_write ^ mstatus) & (MSTATUS_MXR | MSTATUS_MPP |
131                     MSTATUS_MPRV | MSTATUS_SUM)) {
132                 helper_tlb_flush(env);
133             }
134             mask = MSTATUS_SIE | MSTATUS_SPIE | MSTATUS_MIE | MSTATUS_MPIE |
135                 MSTATUS_SPP | MSTATUS_FS | MSTATUS_MPRV | MSTATUS_SUM |
136                 MSTATUS_MPP | MSTATUS_MXR;
137         }
138 
139         /* silenty discard mstatus.mpp writes for unsupported modes */
140         if (mpp == PRV_H ||
141             (!riscv_has_ext(env, RVS) && mpp == PRV_S) ||
142             (!riscv_has_ext(env, RVU) && mpp == PRV_U)) {
143             mask &= ~MSTATUS_MPP;
144         }
145 
146         mstatus = (mstatus & ~mask) | (val_to_write & mask);
147 
148         /* Note: this is a workaround for an issue where mstatus.FS
149            does not report dirty after floating point operations
150            that modify floating point state. This workaround is
151            technically compliant with the RISC-V Privileged
152            specification as it is legal to return only off, or dirty.
153            at the expense of extra floating point save/restore. */
154 
155         /* FP is always dirty or off */
156         if (mstatus & MSTATUS_FS) {
157             mstatus |= MSTATUS_FS;
158         }
159 
160         int dirty = ((mstatus & MSTATUS_FS) == MSTATUS_FS) |
161                     ((mstatus & MSTATUS_XS) == MSTATUS_XS);
162         mstatus = set_field(mstatus, MSTATUS_SD, dirty);
163         env->mstatus = mstatus;
164         break;
165     }
166     case CSR_MIP: {
167         /*
168          * Since the writeable bits in MIP are not set asynchrously by the
169          * CLINT, no additional locking is needed for read-modifiy-write
170          * CSR operations
171          */
172         qemu_mutex_lock_iothread();
173         RISCVCPU *cpu = riscv_env_get_cpu(env);
174         riscv_set_local_interrupt(cpu, MIP_SSIP,
175                                   (val_to_write & MIP_SSIP) != 0);
176         riscv_set_local_interrupt(cpu, MIP_STIP,
177                                   (val_to_write & MIP_STIP) != 0);
178         /*
179          * csrs, csrc on mip.SEIP is not decomposable into separate read and
180          * write steps, so a different implementation is needed
181          */
182         qemu_mutex_unlock_iothread();
183         break;
184     }
185     case CSR_MIE: {
186         env->mie = (env->mie & ~all_ints) |
187             (val_to_write & all_ints);
188         break;
189     }
190     case CSR_MIDELEG:
191         env->mideleg = (env->mideleg & ~delegable_ints)
192                                 | (val_to_write & delegable_ints);
193         break;
194     case CSR_MEDELEG: {
195         target_ulong mask = 0;
196         mask |= 1ULL << (RISCV_EXCP_INST_ADDR_MIS);
197         mask |= 1ULL << (RISCV_EXCP_INST_ACCESS_FAULT);
198         mask |= 1ULL << (RISCV_EXCP_ILLEGAL_INST);
199         mask |= 1ULL << (RISCV_EXCP_BREAKPOINT);
200         mask |= 1ULL << (RISCV_EXCP_LOAD_ADDR_MIS);
201         mask |= 1ULL << (RISCV_EXCP_LOAD_ACCESS_FAULT);
202         mask |= 1ULL << (RISCV_EXCP_STORE_AMO_ADDR_MIS);
203         mask |= 1ULL << (RISCV_EXCP_STORE_AMO_ACCESS_FAULT);
204         mask |= 1ULL << (RISCV_EXCP_U_ECALL);
205         mask |= 1ULL << (RISCV_EXCP_S_ECALL);
206         mask |= 1ULL << (RISCV_EXCP_H_ECALL);
207         mask |= 1ULL << (RISCV_EXCP_M_ECALL);
208         mask |= 1ULL << (RISCV_EXCP_INST_PAGE_FAULT);
209         mask |= 1ULL << (RISCV_EXCP_LOAD_PAGE_FAULT);
210         mask |= 1ULL << (RISCV_EXCP_STORE_PAGE_FAULT);
211         env->medeleg = (env->medeleg & ~mask)
212                                 | (val_to_write & mask);
213         break;
214     }
215     case CSR_MINSTRET:
216         qemu_log_mask(LOG_UNIMP, "CSR_MINSTRET: write not implemented");
217         goto do_illegal;
218     case CSR_MCYCLE:
219         qemu_log_mask(LOG_UNIMP, "CSR_MCYCLE: write not implemented");
220         goto do_illegal;
221     case CSR_MINSTRETH:
222         qemu_log_mask(LOG_UNIMP, "CSR_MINSTRETH: write not implemented");
223         goto do_illegal;
224     case CSR_MCYCLEH:
225         qemu_log_mask(LOG_UNIMP, "CSR_MCYCLEH: write not implemented");
226         goto do_illegal;
227     case CSR_MUCOUNTEREN:
228         env->mucounteren = val_to_write;
229         break;
230     case CSR_MSCOUNTEREN:
231         env->mscounteren = val_to_write;
232         break;
233     case CSR_SSTATUS: {
234         target_ulong ms = env->mstatus;
235         target_ulong mask = SSTATUS_SIE | SSTATUS_SPIE | SSTATUS_UIE
236             | SSTATUS_UPIE | SSTATUS_SPP | SSTATUS_FS | SSTATUS_XS
237             | SSTATUS_SUM | SSTATUS_MXR | SSTATUS_SD;
238         ms = (ms & ~mask) | (val_to_write & mask);
239         csr_write_helper(env, ms, CSR_MSTATUS);
240         break;
241     }
242     case CSR_SIP: {
243         qemu_mutex_lock_iothread();
244         target_ulong next_mip = (env->mip & ~env->mideleg)
245                                 | (val_to_write & env->mideleg);
246         qemu_mutex_unlock_iothread();
247         csr_write_helper(env, next_mip, CSR_MIP);
248         break;
249     }
250     case CSR_SIE: {
251         target_ulong next_mie = (env->mie & ~env->mideleg)
252                                 | (val_to_write & env->mideleg);
253         csr_write_helper(env, next_mie, CSR_MIE);
254         break;
255     }
256     case CSR_SATP: /* CSR_SPTBR */ {
257         if (!riscv_feature(env, RISCV_FEATURE_MMU)) {
258             goto do_illegal;
259         }
260         if (env->priv_ver <= PRIV_VERSION_1_09_1 && (val_to_write ^ env->sptbr))
261         {
262             helper_tlb_flush(env);
263             env->sptbr = val_to_write & (((target_ulong)
264                 1 << (TARGET_PHYS_ADDR_SPACE_BITS - PGSHIFT)) - 1);
265         }
266         if (env->priv_ver >= PRIV_VERSION_1_10_0 &&
267             validate_vm(env, get_field(val_to_write, SATP_MODE)) &&
268             ((val_to_write ^ env->satp) & (SATP_MODE | SATP_ASID | SATP_PPN)))
269         {
270             helper_tlb_flush(env);
271             env->satp = val_to_write;
272         }
273         break;
274     }
275     case CSR_SEPC:
276         env->sepc = val_to_write;
277         break;
278     case CSR_STVEC:
279         if (val_to_write & 1) {
280             qemu_log_mask(LOG_UNIMP, "CSR_STVEC: vectored traps not supported");
281             goto do_illegal;
282         }
283         env->stvec = val_to_write >> 2 << 2;
284         break;
285     case CSR_SCOUNTEREN:
286         env->scounteren = val_to_write;
287         break;
288     case CSR_SSCRATCH:
289         env->sscratch = val_to_write;
290         break;
291     case CSR_SCAUSE:
292         env->scause = val_to_write;
293         break;
294     case CSR_SBADADDR:
295         env->sbadaddr = val_to_write;
296         break;
297     case CSR_MEPC:
298         env->mepc = val_to_write;
299         break;
300     case CSR_MTVEC:
301         if (val_to_write & 1) {
302             qemu_log_mask(LOG_UNIMP, "CSR_MTVEC: vectored traps not supported");
303             goto do_illegal;
304         }
305         env->mtvec = val_to_write >> 2 << 2;
306         break;
307     case CSR_MCOUNTEREN:
308         env->mcounteren = val_to_write;
309         break;
310     case CSR_MSCRATCH:
311         env->mscratch = val_to_write;
312         break;
313     case CSR_MCAUSE:
314         env->mcause = val_to_write;
315         break;
316     case CSR_MBADADDR:
317         env->mbadaddr = val_to_write;
318         break;
319     case CSR_MISA: {
320         qemu_log_mask(LOG_UNIMP, "CSR_MISA: misa writes not supported");
321         goto do_illegal;
322     }
323     case CSR_PMPCFG0:
324     case CSR_PMPCFG1:
325     case CSR_PMPCFG2:
326     case CSR_PMPCFG3:
327        pmpcfg_csr_write(env, csrno - CSR_PMPCFG0, val_to_write);
328        break;
329     case CSR_PMPADDR0:
330     case CSR_PMPADDR1:
331     case CSR_PMPADDR2:
332     case CSR_PMPADDR3:
333     case CSR_PMPADDR4:
334     case CSR_PMPADDR5:
335     case CSR_PMPADDR6:
336     case CSR_PMPADDR7:
337     case CSR_PMPADDR8:
338     case CSR_PMPADDR9:
339     case CSR_PMPADDR10:
340     case CSR_PMPADDR11:
341     case CSR_PMPADDR12:
342     case CSR_PMPADDR13:
343     case CSR_PMPADDR14:
344     case CSR_PMPADDR15:
345        pmpaddr_csr_write(env, csrno - CSR_PMPADDR0, val_to_write);
346        break;
347     do_illegal:
348 #endif
349     default:
350         do_raise_exception_err(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
351     }
352 }
353 
354 /*
355  * Handle reads to CSRs and any resulting special behavior
356  *
357  * Adapted from Spike's processor_t::get_csr
358  */
359 target_ulong csr_read_helper(CPURISCVState *env, target_ulong csrno)
360 {
361 #ifndef CONFIG_USER_ONLY
362     target_ulong ctr_en = env->priv == PRV_U ? env->mucounteren :
363                    env->priv == PRV_S ? env->mscounteren : -1U;
364 #else
365     target_ulong ctr_en = -1;
366 #endif
367     target_ulong ctr_ok = (ctr_en >> (csrno & 31)) & 1;
368 
369     if (csrno >= CSR_HPMCOUNTER3 && csrno <= CSR_HPMCOUNTER31) {
370         if (ctr_ok) {
371             return 0;
372         }
373     }
374 #if defined(TARGET_RISCV32)
375     if (csrno >= CSR_HPMCOUNTER3H && csrno <= CSR_HPMCOUNTER31H) {
376         if (ctr_ok) {
377             return 0;
378         }
379     }
380 #endif
381     if (csrno >= CSR_MHPMCOUNTER3 && csrno <= CSR_MHPMCOUNTER31) {
382         return 0;
383     }
384 #if defined(TARGET_RISCV32)
385     if (csrno >= CSR_MHPMCOUNTER3 && csrno <= CSR_MHPMCOUNTER31) {
386         return 0;
387     }
388 #endif
389     if (csrno >= CSR_MHPMEVENT3 && csrno <= CSR_MHPMEVENT31) {
390         return 0;
391     }
392 
393     switch (csrno) {
394     case CSR_FFLAGS:
395         validate_mstatus_fs(env, GETPC());
396         return cpu_riscv_get_fflags(env);
397     case CSR_FRM:
398         validate_mstatus_fs(env, GETPC());
399         return env->frm;
400     case CSR_FCSR:
401         validate_mstatus_fs(env, GETPC());
402         return (cpu_riscv_get_fflags(env) << FSR_AEXC_SHIFT)
403                 | (env->frm << FSR_RD_SHIFT);
404     /* rdtime/rdtimeh is trapped and emulated by bbl in system mode */
405 #ifdef CONFIG_USER_ONLY
406     case CSR_TIME:
407         return cpu_get_host_ticks();
408 #if defined(TARGET_RISCV32)
409     case CSR_TIMEH:
410         return cpu_get_host_ticks() >> 32;
411 #endif
412 #endif
413     case CSR_INSTRET:
414     case CSR_CYCLE:
415         if (ctr_ok) {
416             return cpu_get_host_ticks();
417         }
418         break;
419 #if defined(TARGET_RISCV32)
420     case CSR_INSTRETH:
421     case CSR_CYCLEH:
422         if (ctr_ok) {
423             return cpu_get_host_ticks() >> 32;
424         }
425         break;
426 #endif
427 #ifndef CONFIG_USER_ONLY
428     case CSR_MINSTRET:
429     case CSR_MCYCLE:
430         return cpu_get_host_ticks();
431     case CSR_MINSTRETH:
432     case CSR_MCYCLEH:
433 #if defined(TARGET_RISCV32)
434         return cpu_get_host_ticks() >> 32;
435 #endif
436         break;
437     case CSR_MUCOUNTEREN:
438         return env->mucounteren;
439     case CSR_MSCOUNTEREN:
440         return env->mscounteren;
441     case CSR_SSTATUS: {
442         target_ulong mask = SSTATUS_SIE | SSTATUS_SPIE | SSTATUS_UIE
443             | SSTATUS_UPIE | SSTATUS_SPP | SSTATUS_FS | SSTATUS_XS
444             | SSTATUS_SUM |  SSTATUS_SD;
445         if (env->priv_ver >= PRIV_VERSION_1_10_0) {
446             mask |= SSTATUS_MXR;
447         }
448         return env->mstatus & mask;
449     }
450     case CSR_SIP: {
451         qemu_mutex_lock_iothread();
452         target_ulong tmp = env->mip & env->mideleg;
453         qemu_mutex_unlock_iothread();
454         return tmp;
455     }
456     case CSR_SIE:
457         return env->mie & env->mideleg;
458     case CSR_SEPC:
459         return env->sepc;
460     case CSR_SBADADDR:
461         return env->sbadaddr;
462     case CSR_STVEC:
463         return env->stvec;
464     case CSR_SCOUNTEREN:
465         return env->scounteren;
466     case CSR_SCAUSE:
467         return env->scause;
468     case CSR_SPTBR:
469         if (env->priv_ver >= PRIV_VERSION_1_10_0) {
470             return env->satp;
471         } else {
472             return env->sptbr;
473         }
474     case CSR_SSCRATCH:
475         return env->sscratch;
476     case CSR_MSTATUS:
477         return env->mstatus;
478     case CSR_MIP: {
479         qemu_mutex_lock_iothread();
480         target_ulong tmp = env->mip;
481         qemu_mutex_unlock_iothread();
482         return tmp;
483     }
484     case CSR_MIE:
485         return env->mie;
486     case CSR_MEPC:
487         return env->mepc;
488     case CSR_MSCRATCH:
489         return env->mscratch;
490     case CSR_MCAUSE:
491         return env->mcause;
492     case CSR_MBADADDR:
493         return env->mbadaddr;
494     case CSR_MISA:
495         return env->misa;
496     case CSR_MARCHID:
497         return 0; /* as spike does */
498     case CSR_MIMPID:
499         return 0; /* as spike does */
500     case CSR_MVENDORID:
501         return 0; /* as spike does */
502     case CSR_MHARTID:
503         return env->mhartid;
504     case CSR_MTVEC:
505         return env->mtvec;
506     case CSR_MCOUNTEREN:
507         return env->mcounteren;
508     case CSR_MEDELEG:
509         return env->medeleg;
510     case CSR_MIDELEG:
511         return env->mideleg;
512     case CSR_PMPCFG0:
513     case CSR_PMPCFG1:
514     case CSR_PMPCFG2:
515     case CSR_PMPCFG3:
516        return pmpcfg_csr_read(env, csrno - CSR_PMPCFG0);
517     case CSR_PMPADDR0:
518     case CSR_PMPADDR1:
519     case CSR_PMPADDR2:
520     case CSR_PMPADDR3:
521     case CSR_PMPADDR4:
522     case CSR_PMPADDR5:
523     case CSR_PMPADDR6:
524     case CSR_PMPADDR7:
525     case CSR_PMPADDR8:
526     case CSR_PMPADDR9:
527     case CSR_PMPADDR10:
528     case CSR_PMPADDR11:
529     case CSR_PMPADDR12:
530     case CSR_PMPADDR13:
531     case CSR_PMPADDR14:
532     case CSR_PMPADDR15:
533        return pmpaddr_csr_read(env, csrno - CSR_PMPADDR0);
534 #endif
535     }
536     /* used by e.g. MTIME read */
537     do_raise_exception_err(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
538 }
539 
540 /*
541  * Check that CSR access is allowed.
542  *
543  * Adapted from Spike's decode.h:validate_csr
544  */
545 static void validate_csr(CPURISCVState *env, uint64_t which,
546                          uint64_t write, uintptr_t ra)
547 {
548 #ifndef CONFIG_USER_ONLY
549     unsigned csr_priv = get_field((which), 0x300);
550     unsigned csr_read_only = get_field((which), 0xC00) == 3;
551     if (((write) && csr_read_only) || (env->priv < csr_priv)) {
552         do_raise_exception_err(env, RISCV_EXCP_ILLEGAL_INST, ra);
553     }
554 #endif
555 }
556 
557 target_ulong helper_csrrw(CPURISCVState *env, target_ulong src,
558         target_ulong csr)
559 {
560     validate_csr(env, csr, 1, GETPC());
561     uint64_t csr_backup = csr_read_helper(env, csr);
562     csr_write_helper(env, src, csr);
563     return csr_backup;
564 }
565 
566 target_ulong helper_csrrs(CPURISCVState *env, target_ulong src,
567         target_ulong csr, target_ulong rs1_pass)
568 {
569     validate_csr(env, csr, rs1_pass != 0, GETPC());
570     uint64_t csr_backup = csr_read_helper(env, csr);
571     if (rs1_pass != 0) {
572         csr_write_helper(env, src | csr_backup, csr);
573     }
574     return csr_backup;
575 }
576 
577 target_ulong helper_csrrc(CPURISCVState *env, target_ulong src,
578         target_ulong csr, target_ulong rs1_pass)
579 {
580     validate_csr(env, csr, rs1_pass != 0, GETPC());
581     uint64_t csr_backup = csr_read_helper(env, csr);
582     if (rs1_pass != 0) {
583         csr_write_helper(env, (~src) & csr_backup, csr);
584     }
585     return csr_backup;
586 }
587 
588 #ifndef CONFIG_USER_ONLY
589 
590 /* iothread_mutex must be held */
591 void riscv_set_local_interrupt(RISCVCPU *cpu, target_ulong mask, int value)
592 {
593     target_ulong old_mip = cpu->env.mip;
594     cpu->env.mip = (old_mip & ~mask) | (value ? mask : 0);
595 
596     if (cpu->env.mip && !old_mip) {
597         cpu_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
598     } else if (!cpu->env.mip && old_mip) {
599         cpu_reset_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
600     }
601 }
602 
603 void riscv_set_mode(CPURISCVState *env, target_ulong newpriv)
604 {
605     if (newpriv > PRV_M) {
606         g_assert_not_reached();
607     }
608     if (newpriv == PRV_H) {
609         newpriv = PRV_U;
610     }
611     /* tlb_flush is unnecessary as mode is contained in mmu_idx */
612     env->priv = newpriv;
613 }
614 
615 target_ulong helper_sret(CPURISCVState *env, target_ulong cpu_pc_deb)
616 {
617     if (!(env->priv >= PRV_S)) {
618         do_raise_exception_err(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
619     }
620 
621     target_ulong retpc = env->sepc;
622     if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
623         do_raise_exception_err(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
624     }
625 
626     target_ulong mstatus = env->mstatus;
627     target_ulong prev_priv = get_field(mstatus, MSTATUS_SPP);
628     mstatus = set_field(mstatus,
629         env->priv_ver >= PRIV_VERSION_1_10_0 ?
630         MSTATUS_SIE : MSTATUS_UIE << prev_priv,
631         get_field(mstatus, MSTATUS_SPIE));
632     mstatus = set_field(mstatus, MSTATUS_SPIE, 0);
633     mstatus = set_field(mstatus, MSTATUS_SPP, PRV_U);
634     riscv_set_mode(env, prev_priv);
635     csr_write_helper(env, mstatus, CSR_MSTATUS);
636 
637     return retpc;
638 }
639 
640 target_ulong helper_mret(CPURISCVState *env, target_ulong cpu_pc_deb)
641 {
642     if (!(env->priv >= PRV_M)) {
643         do_raise_exception_err(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
644     }
645 
646     target_ulong retpc = env->mepc;
647     if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
648         do_raise_exception_err(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
649     }
650 
651     target_ulong mstatus = env->mstatus;
652     target_ulong prev_priv = get_field(mstatus, MSTATUS_MPP);
653     mstatus = set_field(mstatus,
654         env->priv_ver >= PRIV_VERSION_1_10_0 ?
655         MSTATUS_MIE : MSTATUS_UIE << prev_priv,
656         get_field(mstatus, MSTATUS_MPIE));
657     mstatus = set_field(mstatus, MSTATUS_MPIE, 0);
658     mstatus = set_field(mstatus, MSTATUS_MPP, PRV_U);
659     riscv_set_mode(env, prev_priv);
660     csr_write_helper(env, mstatus, CSR_MSTATUS);
661 
662     return retpc;
663 }
664 
665 
666 void helper_wfi(CPURISCVState *env)
667 {
668     CPUState *cs = CPU(riscv_env_get_cpu(env));
669 
670     cs->halted = 1;
671     cs->exception_index = EXCP_HLT;
672     cpu_loop_exit(cs);
673 }
674 
675 void helper_tlb_flush(CPURISCVState *env)
676 {
677     RISCVCPU *cpu = riscv_env_get_cpu(env);
678     CPUState *cs = CPU(cpu);
679     tlb_flush(cs);
680 }
681 
682 #endif /* !CONFIG_USER_ONLY */
683