xref: /openbmc/qemu/target/riscv/cpu_helper.c (revision 37207e12)
1 /*
2  * RISC-V CPU 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 "exec/exec-all.h"
24 #include "tcg-op.h"
25 #include "trace.h"
26 
27 int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
28 {
29 #ifdef CONFIG_USER_ONLY
30     return 0;
31 #else
32     return env->priv;
33 #endif
34 }
35 
36 #ifndef CONFIG_USER_ONLY
37 static int riscv_cpu_local_irq_pending(CPURISCVState *env)
38 {
39     target_ulong mstatus_mie = get_field(env->mstatus, MSTATUS_MIE);
40     target_ulong mstatus_sie = get_field(env->mstatus, MSTATUS_SIE);
41     target_ulong pending = atomic_read(&env->mip) & env->mie;
42     target_ulong mie = env->priv < PRV_M || (env->priv == PRV_M && mstatus_mie);
43     target_ulong sie = env->priv < PRV_S || (env->priv == PRV_S && mstatus_sie);
44     target_ulong irqs = (pending & ~env->mideleg & -mie) |
45                         (pending &  env->mideleg & -sie);
46 
47     if (irqs) {
48         return ctz64(irqs); /* since non-zero */
49     } else {
50         return EXCP_NONE; /* indicates no pending interrupt */
51     }
52 }
53 #endif
54 
55 bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
56 {
57 #if !defined(CONFIG_USER_ONLY)
58     if (interrupt_request & CPU_INTERRUPT_HARD) {
59         RISCVCPU *cpu = RISCV_CPU(cs);
60         CPURISCVState *env = &cpu->env;
61         int interruptno = riscv_cpu_local_irq_pending(env);
62         if (interruptno >= 0) {
63             cs->exception_index = RISCV_EXCP_INT_FLAG | interruptno;
64             riscv_cpu_do_interrupt(cs);
65             return true;
66         }
67     }
68 #endif
69     return false;
70 }
71 
72 #if !defined(CONFIG_USER_ONLY)
73 
74 /* Return true is floating point support is currently enabled */
75 bool riscv_cpu_fp_enabled(CPURISCVState *env)
76 {
77     if (env->mstatus & MSTATUS_FS) {
78         return true;
79     }
80 
81     return false;
82 }
83 
84 int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint32_t interrupts)
85 {
86     CPURISCVState *env = &cpu->env;
87     if (env->miclaim & interrupts) {
88         return -1;
89     } else {
90         env->miclaim |= interrupts;
91         return 0;
92     }
93 }
94 
95 struct CpuAsyncInfo {
96     uint32_t new_mip;
97 };
98 
99 static void riscv_cpu_update_mip_irqs_async(CPUState *target_cpu_state,
100                                             run_on_cpu_data data)
101 {
102     struct CpuAsyncInfo *info = (struct CpuAsyncInfo *) data.host_ptr;
103 
104     if (info->new_mip) {
105         cpu_interrupt(target_cpu_state, CPU_INTERRUPT_HARD);
106     } else {
107         cpu_reset_interrupt(target_cpu_state, CPU_INTERRUPT_HARD);
108     }
109 
110     g_free(info);
111 }
112 
113 uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value)
114 {
115     CPURISCVState *env = &cpu->env;
116     CPUState *cs = CPU(cpu);
117     struct CpuAsyncInfo *info;
118     uint32_t old, new, cmp = atomic_read(&env->mip);
119 
120     do {
121         old = cmp;
122         new = (old & ~mask) | (value & mask);
123         cmp = atomic_cmpxchg(&env->mip, old, new);
124     } while (old != cmp);
125 
126     info = g_new(struct CpuAsyncInfo, 1);
127     info->new_mip = new;
128 
129     async_run_on_cpu(cs, riscv_cpu_update_mip_irqs_async,
130                      RUN_ON_CPU_HOST_PTR(info));
131 
132     return old;
133 }
134 
135 void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv)
136 {
137     if (newpriv > PRV_M) {
138         g_assert_not_reached();
139     }
140     if (newpriv == PRV_H) {
141         newpriv = PRV_U;
142     }
143     /* tlb_flush is unnecessary as mode is contained in mmu_idx */
144     env->priv = newpriv;
145 
146     /*
147      * Clear the load reservation - otherwise a reservation placed in one
148      * context/process can be used by another, resulting in an SC succeeding
149      * incorrectly. Version 2.2 of the ISA specification explicitly requires
150      * this behaviour, while later revisions say that the kernel "should" use
151      * an SC instruction to force the yielding of a load reservation on a
152      * preemptive context switch. As a result, do both.
153      */
154     env->load_res = -1;
155 }
156 
157 /* get_physical_address - get the physical address for this virtual address
158  *
159  * Do a page table walk to obtain the physical address corresponding to a
160  * virtual address. Returns 0 if the translation was successful
161  *
162  * Adapted from Spike's mmu_t::translate and mmu_t::walk
163  *
164  */
165 static int get_physical_address(CPURISCVState *env, hwaddr *physical,
166                                 int *prot, target_ulong addr,
167                                 int access_type, int mmu_idx)
168 {
169     /* NOTE: the env->pc value visible here will not be
170      * correct, but the value visible to the exception handler
171      * (riscv_cpu_do_interrupt) is correct */
172     MemTxResult res;
173     MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
174     int mode = mmu_idx;
175 
176     if (mode == PRV_M && access_type != MMU_INST_FETCH) {
177         if (get_field(env->mstatus, MSTATUS_MPRV)) {
178             mode = get_field(env->mstatus, MSTATUS_MPP);
179         }
180     }
181 
182     if (mode == PRV_M || !riscv_feature(env, RISCV_FEATURE_MMU)) {
183         *physical = addr;
184         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
185         return TRANSLATE_SUCCESS;
186     }
187 
188     *prot = 0;
189 
190     hwaddr base;
191     int levels, ptidxbits, ptesize, vm, sum;
192     int mxr = get_field(env->mstatus, MSTATUS_MXR);
193 
194     if (env->priv_ver >= PRIV_VERSION_1_10_0) {
195         base = (hwaddr)get_field(env->satp, SATP_PPN) << PGSHIFT;
196         sum = get_field(env->mstatus, MSTATUS_SUM);
197         vm = get_field(env->satp, SATP_MODE);
198         switch (vm) {
199         case VM_1_10_SV32:
200           levels = 2; ptidxbits = 10; ptesize = 4; break;
201         case VM_1_10_SV39:
202           levels = 3; ptidxbits = 9; ptesize = 8; break;
203         case VM_1_10_SV48:
204           levels = 4; ptidxbits = 9; ptesize = 8; break;
205         case VM_1_10_SV57:
206           levels = 5; ptidxbits = 9; ptesize = 8; break;
207         case VM_1_10_MBARE:
208             *physical = addr;
209             *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
210             return TRANSLATE_SUCCESS;
211         default:
212           g_assert_not_reached();
213         }
214     } else {
215         base = (hwaddr)(env->sptbr) << PGSHIFT;
216         sum = !get_field(env->mstatus, MSTATUS_PUM);
217         vm = get_field(env->mstatus, MSTATUS_VM);
218         switch (vm) {
219         case VM_1_09_SV32:
220           levels = 2; ptidxbits = 10; ptesize = 4; break;
221         case VM_1_09_SV39:
222           levels = 3; ptidxbits = 9; ptesize = 8; break;
223         case VM_1_09_SV48:
224           levels = 4; ptidxbits = 9; ptesize = 8; break;
225         case VM_1_09_MBARE:
226             *physical = addr;
227             *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
228             return TRANSLATE_SUCCESS;
229         default:
230           g_assert_not_reached();
231         }
232     }
233 
234     CPUState *cs = env_cpu(env);
235     int va_bits = PGSHIFT + levels * ptidxbits;
236     target_ulong mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
237     target_ulong masked_msbs = (addr >> (va_bits - 1)) & mask;
238     if (masked_msbs != 0 && masked_msbs != mask) {
239         return TRANSLATE_FAIL;
240     }
241 
242     int ptshift = (levels - 1) * ptidxbits;
243     int i;
244 
245 #if !TCG_OVERSIZED_GUEST
246 restart:
247 #endif
248     for (i = 0; i < levels; i++, ptshift -= ptidxbits) {
249         target_ulong idx = (addr >> (PGSHIFT + ptshift)) &
250                            ((1 << ptidxbits) - 1);
251 
252         /* check that physical address of PTE is legal */
253         hwaddr pte_addr = base + idx * ptesize;
254 
255         if (riscv_feature(env, RISCV_FEATURE_PMP) &&
256             !pmp_hart_has_privs(env, pte_addr, sizeof(target_ulong),
257             1 << MMU_DATA_LOAD, PRV_S)) {
258             return TRANSLATE_PMP_FAIL;
259         }
260 
261 #if defined(TARGET_RISCV32)
262         target_ulong pte = address_space_ldl(cs->as, pte_addr, attrs, &res);
263 #elif defined(TARGET_RISCV64)
264         target_ulong pte = address_space_ldq(cs->as, pte_addr, attrs, &res);
265 #endif
266         if (res != MEMTX_OK) {
267             return TRANSLATE_FAIL;
268         }
269 
270         hwaddr ppn = pte >> PTE_PPN_SHIFT;
271 
272         if (!(pte & PTE_V)) {
273             /* Invalid PTE */
274             return TRANSLATE_FAIL;
275         } else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
276             /* Inner PTE, continue walking */
277             base = ppn << PGSHIFT;
278         } else if ((pte & (PTE_R | PTE_W | PTE_X)) == PTE_W) {
279             /* Reserved leaf PTE flags: PTE_W */
280             return TRANSLATE_FAIL;
281         } else if ((pte & (PTE_R | PTE_W | PTE_X)) == (PTE_W | PTE_X)) {
282             /* Reserved leaf PTE flags: PTE_W + PTE_X */
283             return TRANSLATE_FAIL;
284         } else if ((pte & PTE_U) && ((mode != PRV_U) &&
285                    (!sum || access_type == MMU_INST_FETCH))) {
286             /* User PTE flags when not U mode and mstatus.SUM is not set,
287                or the access type is an instruction fetch */
288             return TRANSLATE_FAIL;
289         } else if (!(pte & PTE_U) && (mode != PRV_S)) {
290             /* Supervisor PTE flags when not S mode */
291             return TRANSLATE_FAIL;
292         } else if (ppn & ((1ULL << ptshift) - 1)) {
293             /* Misaligned PPN */
294             return TRANSLATE_FAIL;
295         } else if (access_type == MMU_DATA_LOAD && !((pte & PTE_R) ||
296                    ((pte & PTE_X) && mxr))) {
297             /* Read access check failed */
298             return TRANSLATE_FAIL;
299         } else if (access_type == MMU_DATA_STORE && !(pte & PTE_W)) {
300             /* Write access check failed */
301             return TRANSLATE_FAIL;
302         } else if (access_type == MMU_INST_FETCH && !(pte & PTE_X)) {
303             /* Fetch access check failed */
304             return TRANSLATE_FAIL;
305         } else {
306             /* if necessary, set accessed and dirty bits. */
307             target_ulong updated_pte = pte | PTE_A |
308                 (access_type == MMU_DATA_STORE ? PTE_D : 0);
309 
310             /* Page table updates need to be atomic with MTTCG enabled */
311             if (updated_pte != pte) {
312                 /*
313                  * - if accessed or dirty bits need updating, and the PTE is
314                  *   in RAM, then we do so atomically with a compare and swap.
315                  * - if the PTE is in IO space or ROM, then it can't be updated
316                  *   and we return TRANSLATE_FAIL.
317                  * - if the PTE changed by the time we went to update it, then
318                  *   it is no longer valid and we must re-walk the page table.
319                  */
320                 MemoryRegion *mr;
321                 hwaddr l = sizeof(target_ulong), addr1;
322                 mr = address_space_translate(cs->as, pte_addr,
323                     &addr1, &l, false, MEMTXATTRS_UNSPECIFIED);
324                 if (memory_region_is_ram(mr)) {
325                     target_ulong *pte_pa =
326                         qemu_map_ram_ptr(mr->ram_block, addr1);
327 #if TCG_OVERSIZED_GUEST
328                     /* MTTCG is not enabled on oversized TCG guests so
329                      * page table updates do not need to be atomic */
330                     *pte_pa = pte = updated_pte;
331 #else
332                     target_ulong old_pte =
333                         atomic_cmpxchg(pte_pa, pte, updated_pte);
334                     if (old_pte != pte) {
335                         goto restart;
336                     } else {
337                         pte = updated_pte;
338                     }
339 #endif
340                 } else {
341                     /* misconfigured PTE in ROM (AD bits are not preset) or
342                      * PTE is in IO space and can't be updated atomically */
343                     return TRANSLATE_FAIL;
344                 }
345             }
346 
347             /* for superpage mappings, make a fake leaf PTE for the TLB's
348                benefit. */
349             target_ulong vpn = addr >> PGSHIFT;
350             *physical = (ppn | (vpn & ((1L << ptshift) - 1))) << PGSHIFT;
351 
352             /* set permissions on the TLB entry */
353             if ((pte & PTE_R) || ((pte & PTE_X) && mxr)) {
354                 *prot |= PAGE_READ;
355             }
356             if ((pte & PTE_X)) {
357                 *prot |= PAGE_EXEC;
358             }
359             /* add write permission on stores or if the page is already dirty,
360                so that we TLB miss on later writes to update the dirty bit */
361             if ((pte & PTE_W) &&
362                     (access_type == MMU_DATA_STORE || (pte & PTE_D))) {
363                 *prot |= PAGE_WRITE;
364             }
365             return TRANSLATE_SUCCESS;
366         }
367     }
368     return TRANSLATE_FAIL;
369 }
370 
371 static void raise_mmu_exception(CPURISCVState *env, target_ulong address,
372                                 MMUAccessType access_type, bool pmp_violation)
373 {
374     CPUState *cs = env_cpu(env);
375     int page_fault_exceptions =
376         (env->priv_ver >= PRIV_VERSION_1_10_0) &&
377         get_field(env->satp, SATP_MODE) != VM_1_10_MBARE &&
378         !pmp_violation;
379     switch (access_type) {
380     case MMU_INST_FETCH:
381         cs->exception_index = page_fault_exceptions ?
382             RISCV_EXCP_INST_PAGE_FAULT : RISCV_EXCP_INST_ACCESS_FAULT;
383         break;
384     case MMU_DATA_LOAD:
385         cs->exception_index = page_fault_exceptions ?
386             RISCV_EXCP_LOAD_PAGE_FAULT : RISCV_EXCP_LOAD_ACCESS_FAULT;
387         break;
388     case MMU_DATA_STORE:
389         cs->exception_index = page_fault_exceptions ?
390             RISCV_EXCP_STORE_PAGE_FAULT : RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
391         break;
392     default:
393         g_assert_not_reached();
394     }
395     env->badaddr = address;
396 }
397 
398 hwaddr riscv_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
399 {
400     RISCVCPU *cpu = RISCV_CPU(cs);
401     hwaddr phys_addr;
402     int prot;
403     int mmu_idx = cpu_mmu_index(&cpu->env, false);
404 
405     if (get_physical_address(&cpu->env, &phys_addr, &prot, addr, 0, mmu_idx)) {
406         return -1;
407     }
408     return phys_addr;
409 }
410 
411 void riscv_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
412                                      vaddr addr, unsigned size,
413                                      MMUAccessType access_type,
414                                      int mmu_idx, MemTxAttrs attrs,
415                                      MemTxResult response, uintptr_t retaddr)
416 {
417     RISCVCPU *cpu = RISCV_CPU(cs);
418     CPURISCVState *env = &cpu->env;
419 
420     if (access_type == MMU_DATA_STORE) {
421         cs->exception_index = RISCV_EXCP_STORE_AMO_ACCESS_FAULT;
422     } else {
423         cs->exception_index = RISCV_EXCP_LOAD_ACCESS_FAULT;
424     }
425 
426     env->badaddr = addr;
427     riscv_raise_exception(&cpu->env, cs->exception_index, retaddr);
428 }
429 
430 void riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
431                                    MMUAccessType access_type, int mmu_idx,
432                                    uintptr_t retaddr)
433 {
434     RISCVCPU *cpu = RISCV_CPU(cs);
435     CPURISCVState *env = &cpu->env;
436     switch (access_type) {
437     case MMU_INST_FETCH:
438         cs->exception_index = RISCV_EXCP_INST_ADDR_MIS;
439         break;
440     case MMU_DATA_LOAD:
441         cs->exception_index = RISCV_EXCP_LOAD_ADDR_MIS;
442         break;
443     case MMU_DATA_STORE:
444         cs->exception_index = RISCV_EXCP_STORE_AMO_ADDR_MIS;
445         break;
446     default:
447         g_assert_not_reached();
448     }
449     env->badaddr = addr;
450     riscv_raise_exception(env, cs->exception_index, retaddr);
451 }
452 #endif
453 
454 bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
455                         MMUAccessType access_type, int mmu_idx,
456                         bool probe, uintptr_t retaddr)
457 {
458 #ifndef CONFIG_USER_ONLY
459     RISCVCPU *cpu = RISCV_CPU(cs);
460     CPURISCVState *env = &cpu->env;
461     hwaddr pa = 0;
462     int prot;
463     bool pmp_violation = false;
464     int ret = TRANSLATE_FAIL;
465     int mode = mmu_idx;
466 
467     qemu_log_mask(CPU_LOG_MMU, "%s ad %" VADDR_PRIx " rw %d mmu_idx %d\n",
468                   __func__, address, access_type, mmu_idx);
469 
470     ret = get_physical_address(env, &pa, &prot, address, access_type, mmu_idx);
471 
472     if (mode == PRV_M && access_type != MMU_INST_FETCH) {
473         if (get_field(env->mstatus, MSTATUS_MPRV)) {
474             mode = get_field(env->mstatus, MSTATUS_MPP);
475         }
476     }
477 
478     qemu_log_mask(CPU_LOG_MMU,
479                   "%s address=%" VADDR_PRIx " ret %d physical " TARGET_FMT_plx
480                   " prot %d\n", __func__, address, ret, pa, prot);
481 
482     if (riscv_feature(env, RISCV_FEATURE_PMP) &&
483         (ret == TRANSLATE_SUCCESS) &&
484         !pmp_hart_has_privs(env, pa, size, 1 << access_type, mode)) {
485         ret = TRANSLATE_PMP_FAIL;
486     }
487     if (ret == TRANSLATE_PMP_FAIL) {
488         pmp_violation = true;
489     }
490     if (ret == TRANSLATE_SUCCESS) {
491         tlb_set_page(cs, address & TARGET_PAGE_MASK, pa & TARGET_PAGE_MASK,
492                      prot, mmu_idx, TARGET_PAGE_SIZE);
493         return true;
494     } else if (probe) {
495         return false;
496     } else {
497         raise_mmu_exception(env, address, access_type, pmp_violation);
498         riscv_raise_exception(env, cs->exception_index, retaddr);
499     }
500 #else
501     switch (access_type) {
502     case MMU_INST_FETCH:
503         cs->exception_index = RISCV_EXCP_INST_PAGE_FAULT;
504         break;
505     case MMU_DATA_LOAD:
506         cs->exception_index = RISCV_EXCP_LOAD_PAGE_FAULT;
507         break;
508     case MMU_DATA_STORE:
509         cs->exception_index = RISCV_EXCP_STORE_PAGE_FAULT;
510         break;
511     }
512     cpu_loop_exit_restore(cs, retaddr);
513 #endif
514 }
515 
516 /*
517  * Handle Traps
518  *
519  * Adapted from Spike's processor_t::take_trap.
520  *
521  */
522 void riscv_cpu_do_interrupt(CPUState *cs)
523 {
524 #if !defined(CONFIG_USER_ONLY)
525 
526     RISCVCPU *cpu = RISCV_CPU(cs);
527     CPURISCVState *env = &cpu->env;
528 
529     /* cs->exception is 32-bits wide unlike mcause which is XLEN-bits wide
530      * so we mask off the MSB and separate into trap type and cause.
531      */
532     bool async = !!(cs->exception_index & RISCV_EXCP_INT_FLAG);
533     target_ulong cause = cs->exception_index & RISCV_EXCP_INT_MASK;
534     target_ulong deleg = async ? env->mideleg : env->medeleg;
535     target_ulong tval = 0;
536 
537     static const int ecall_cause_map[] = {
538         [PRV_U] = RISCV_EXCP_U_ECALL,
539         [PRV_S] = RISCV_EXCP_S_ECALL,
540         [PRV_H] = RISCV_EXCP_H_ECALL,
541         [PRV_M] = RISCV_EXCP_M_ECALL
542     };
543 
544     if (!async) {
545         /* set tval to badaddr for traps with address information */
546         switch (cause) {
547         case RISCV_EXCP_INST_ADDR_MIS:
548         case RISCV_EXCP_INST_ACCESS_FAULT:
549         case RISCV_EXCP_LOAD_ADDR_MIS:
550         case RISCV_EXCP_STORE_AMO_ADDR_MIS:
551         case RISCV_EXCP_LOAD_ACCESS_FAULT:
552         case RISCV_EXCP_STORE_AMO_ACCESS_FAULT:
553         case RISCV_EXCP_INST_PAGE_FAULT:
554         case RISCV_EXCP_LOAD_PAGE_FAULT:
555         case RISCV_EXCP_STORE_PAGE_FAULT:
556             tval = env->badaddr;
557             break;
558         default:
559             break;
560         }
561         /* ecall is dispatched as one cause so translate based on mode */
562         if (cause == RISCV_EXCP_U_ECALL) {
563             assert(env->priv <= 3);
564             cause = ecall_cause_map[env->priv];
565         }
566     }
567 
568     trace_riscv_trap(env->mhartid, async, cause, env->pc, tval, cause < 16 ?
569         (async ? riscv_intr_names : riscv_excp_names)[cause] : "(unknown)");
570 
571     if (env->priv <= PRV_S &&
572             cause < TARGET_LONG_BITS && ((deleg >> cause) & 1)) {
573         /* handle the trap in S-mode */
574         target_ulong s = env->mstatus;
575         s = set_field(s, MSTATUS_SPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
576             get_field(s, MSTATUS_SIE) : get_field(s, MSTATUS_UIE << env->priv));
577         s = set_field(s, MSTATUS_SPP, env->priv);
578         s = set_field(s, MSTATUS_SIE, 0);
579         env->mstatus = s;
580         env->scause = cause | ((target_ulong)async << (TARGET_LONG_BITS - 1));
581         env->sepc = env->pc;
582         env->sbadaddr = tval;
583         env->pc = (env->stvec >> 2 << 2) +
584             ((async && (env->stvec & 3) == 1) ? cause * 4 : 0);
585         riscv_cpu_set_mode(env, PRV_S);
586     } else {
587         /* handle the trap in M-mode */
588         target_ulong s = env->mstatus;
589         s = set_field(s, MSTATUS_MPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
590             get_field(s, MSTATUS_MIE) : get_field(s, MSTATUS_UIE << env->priv));
591         s = set_field(s, MSTATUS_MPP, env->priv);
592         s = set_field(s, MSTATUS_MIE, 0);
593         env->mstatus = s;
594         env->mcause = cause | ~(((target_ulong)-1) >> async);
595         env->mepc = env->pc;
596         env->mbadaddr = tval;
597         env->pc = (env->mtvec >> 2 << 2) +
598             ((async && (env->mtvec & 3) == 1) ? cause * 4 : 0);
599         riscv_cpu_set_mode(env, PRV_M);
600     }
601 
602     /* NOTE: it is not necessary to yield load reservations here. It is only
603      * necessary for an SC from "another hart" to cause a load reservation
604      * to be yielded. Refer to the memory consistency model section of the
605      * RISC-V ISA Specification.
606      */
607 
608 #endif
609     cs->exception_index = EXCP_NONE; /* mark handled to qemu */
610 }
611