xref: /openbmc/qemu/accel/tcg/user-exec.c (revision 135b03cb)
1 /*
2  *  User emulator execution
3  *
4  *  Copyright (c) 2003-2005 Fabrice Bellard
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18  */
19 #include "qemu/osdep.h"
20 #include "cpu.h"
21 #include "disas/disas.h"
22 #include "exec/exec-all.h"
23 #include "tcg.h"
24 #include "qemu/bitops.h"
25 #include "exec/cpu_ldst.h"
26 #include "translate-all.h"
27 #include "exec/helper-proto.h"
28 #include "qemu/atomic128.h"
29 
30 #undef EAX
31 #undef ECX
32 #undef EDX
33 #undef EBX
34 #undef ESP
35 #undef EBP
36 #undef ESI
37 #undef EDI
38 #undef EIP
39 #ifdef __linux__
40 #include <sys/ucontext.h>
41 #endif
42 
43 __thread uintptr_t helper_retaddr;
44 
45 //#define DEBUG_SIGNAL
46 
47 /* exit the current TB from a signal handler. The host registers are
48    restored in a state compatible with the CPU emulator
49  */
50 static void cpu_exit_tb_from_sighandler(CPUState *cpu, sigset_t *old_set)
51 {
52     /* XXX: use siglongjmp ? */
53     sigprocmask(SIG_SETMASK, old_set, NULL);
54     cpu_loop_exit_noexc(cpu);
55 }
56 
57 /* 'pc' is the host PC at which the exception was raised. 'address' is
58    the effective address of the memory exception. 'is_write' is 1 if a
59    write caused the exception and otherwise 0'. 'old_set' is the
60    signal set which should be restored */
61 static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
62                                     int is_write, sigset_t *old_set)
63 {
64     CPUState *cpu = current_cpu;
65     CPUClass *cc;
66     unsigned long address = (unsigned long)info->si_addr;
67     MMUAccessType access_type = is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
68 
69     switch (helper_retaddr) {
70     default:
71         /*
72          * Fault during host memory operation within a helper function.
73          * The helper's host return address, saved here, gives us a
74          * pointer into the generated code that will unwind to the
75          * correct guest pc.
76          */
77         pc = helper_retaddr;
78         break;
79 
80     case 0:
81         /*
82          * Fault during host memory operation within generated code.
83          * (Or, a unrelated bug within qemu, but we can't tell from here).
84          *
85          * We take the host pc from the signal frame.  However, we cannot
86          * use that value directly.  Within cpu_restore_state_from_tb, we
87          * assume PC comes from GETPC(), as used by the helper functions,
88          * so we adjust the address by -GETPC_ADJ to form an address that
89          * is within the call insn, so that the address does not accidentially
90          * match the beginning of the next guest insn.  However, when the
91          * pc comes from the signal frame it points to the actual faulting
92          * host memory insn and not the return from a call insn.
93          *
94          * Therefore, adjust to compensate for what will be done later
95          * by cpu_restore_state_from_tb.
96          */
97         pc += GETPC_ADJ;
98         break;
99 
100     case 1:
101         /*
102          * Fault during host read for translation, or loosely, "execution".
103          *
104          * The guest pc is already pointing to the start of the TB for which
105          * code is being generated.  If the guest translator manages the
106          * page crossings correctly, this is exactly the correct address
107          * (and if the translator doesn't handle page boundaries correctly
108          * there's little we can do about that here).  Therefore, do not
109          * trigger the unwinder.
110          *
111          * Like tb_gen_code, release the memory lock before cpu_loop_exit.
112          */
113         pc = 0;
114         access_type = MMU_INST_FETCH;
115         mmap_unlock();
116         break;
117     }
118 
119     /* For synchronous signals we expect to be coming from the vCPU
120      * thread (so current_cpu should be valid) and either from running
121      * code or during translation which can fault as we cross pages.
122      *
123      * If neither is true then something has gone wrong and we should
124      * abort rather than try and restart the vCPU execution.
125      */
126     if (!cpu || !cpu->running) {
127         printf("qemu:%s received signal outside vCPU context @ pc=0x%"
128                PRIxPTR "\n",  __func__, pc);
129         abort();
130     }
131 
132 #if defined(DEBUG_SIGNAL)
133     printf("qemu: SIGSEGV pc=0x%08lx address=%08lx w=%d oldset=0x%08lx\n",
134            pc, address, is_write, *(unsigned long *)old_set);
135 #endif
136     /* XXX: locking issue */
137     /* Note that it is important that we don't call page_unprotect() unless
138      * this is really a "write to nonwriteable page" fault, because
139      * page_unprotect() assumes that if it is called for an access to
140      * a page that's writeable this means we had two threads racing and
141      * another thread got there first and already made the page writeable;
142      * so we will retry the access. If we were to call page_unprotect()
143      * for some other kind of fault that should really be passed to the
144      * guest, we'd end up in an infinite loop of retrying the faulting
145      * access.
146      */
147     if (is_write && info->si_signo == SIGSEGV && info->si_code == SEGV_ACCERR &&
148         h2g_valid(address)) {
149         switch (page_unprotect(h2g(address), pc)) {
150         case 0:
151             /* Fault not caused by a page marked unwritable to protect
152              * cached translations, must be the guest binary's problem.
153              */
154             break;
155         case 1:
156             /* Fault caused by protection of cached translation; TBs
157              * invalidated, so resume execution.  Retain helper_retaddr
158              * for a possible second fault.
159              */
160             return 1;
161         case 2:
162             /* Fault caused by protection of cached translation, and the
163              * currently executing TB was modified and must be exited
164              * immediately.  Clear helper_retaddr for next execution.
165              */
166             clear_helper_retaddr();
167             cpu_exit_tb_from_sighandler(cpu, old_set);
168             /* NORETURN */
169 
170         default:
171             g_assert_not_reached();
172         }
173     }
174 
175     /* Convert forcefully to guest address space, invalid addresses
176        are still valid segv ones */
177     address = h2g_nocheck(address);
178 
179     /*
180      * There is no way the target can handle this other than raising
181      * an exception.  Undo signal and retaddr state prior to longjmp.
182      */
183     sigprocmask(SIG_SETMASK, old_set, NULL);
184     clear_helper_retaddr();
185 
186     cc = CPU_GET_CLASS(cpu);
187     cc->tlb_fill(cpu, address, 0, access_type, MMU_USER_IDX, false, pc);
188     g_assert_not_reached();
189 }
190 
191 #if defined(__i386__)
192 
193 #if defined(__NetBSD__)
194 #include <ucontext.h>
195 
196 #define EIP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_EIP])
197 #define TRAP_sig(context)    ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
198 #define ERROR_sig(context)   ((context)->uc_mcontext.__gregs[_REG_ERR])
199 #define MASK_sig(context)    ((context)->uc_sigmask)
200 #elif defined(__FreeBSD__) || defined(__DragonFly__)
201 #include <ucontext.h>
202 
203 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_eip))
204 #define TRAP_sig(context)    ((context)->uc_mcontext.mc_trapno)
205 #define ERROR_sig(context)   ((context)->uc_mcontext.mc_err)
206 #define MASK_sig(context)    ((context)->uc_sigmask)
207 #elif defined(__OpenBSD__)
208 #define EIP_sig(context)     ((context)->sc_eip)
209 #define TRAP_sig(context)    ((context)->sc_trapno)
210 #define ERROR_sig(context)   ((context)->sc_err)
211 #define MASK_sig(context)    ((context)->sc_mask)
212 #else
213 #define EIP_sig(context)     ((context)->uc_mcontext.gregs[REG_EIP])
214 #define TRAP_sig(context)    ((context)->uc_mcontext.gregs[REG_TRAPNO])
215 #define ERROR_sig(context)   ((context)->uc_mcontext.gregs[REG_ERR])
216 #define MASK_sig(context)    ((context)->uc_sigmask)
217 #endif
218 
219 int cpu_signal_handler(int host_signum, void *pinfo,
220                        void *puc)
221 {
222     siginfo_t *info = pinfo;
223 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
224     ucontext_t *uc = puc;
225 #elif defined(__OpenBSD__)
226     struct sigcontext *uc = puc;
227 #else
228     ucontext_t *uc = puc;
229 #endif
230     unsigned long pc;
231     int trapno;
232 
233 #ifndef REG_EIP
234 /* for glibc 2.1 */
235 #define REG_EIP    EIP
236 #define REG_ERR    ERR
237 #define REG_TRAPNO TRAPNO
238 #endif
239     pc = EIP_sig(uc);
240     trapno = TRAP_sig(uc);
241     return handle_cpu_signal(pc, info,
242                              trapno == 0xe ? (ERROR_sig(uc) >> 1) & 1 : 0,
243                              &MASK_sig(uc));
244 }
245 
246 #elif defined(__x86_64__)
247 
248 #ifdef __NetBSD__
249 #define PC_sig(context)       _UC_MACHINE_PC(context)
250 #define TRAP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
251 #define ERROR_sig(context)    ((context)->uc_mcontext.__gregs[_REG_ERR])
252 #define MASK_sig(context)     ((context)->uc_sigmask)
253 #elif defined(__OpenBSD__)
254 #define PC_sig(context)       ((context)->sc_rip)
255 #define TRAP_sig(context)     ((context)->sc_trapno)
256 #define ERROR_sig(context)    ((context)->sc_err)
257 #define MASK_sig(context)     ((context)->sc_mask)
258 #elif defined(__FreeBSD__) || defined(__DragonFly__)
259 #include <ucontext.h>
260 
261 #define PC_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_rip))
262 #define TRAP_sig(context)     ((context)->uc_mcontext.mc_trapno)
263 #define ERROR_sig(context)    ((context)->uc_mcontext.mc_err)
264 #define MASK_sig(context)     ((context)->uc_sigmask)
265 #else
266 #define PC_sig(context)       ((context)->uc_mcontext.gregs[REG_RIP])
267 #define TRAP_sig(context)     ((context)->uc_mcontext.gregs[REG_TRAPNO])
268 #define ERROR_sig(context)    ((context)->uc_mcontext.gregs[REG_ERR])
269 #define MASK_sig(context)     ((context)->uc_sigmask)
270 #endif
271 
272 int cpu_signal_handler(int host_signum, void *pinfo,
273                        void *puc)
274 {
275     siginfo_t *info = pinfo;
276     unsigned long pc;
277 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
278     ucontext_t *uc = puc;
279 #elif defined(__OpenBSD__)
280     struct sigcontext *uc = puc;
281 #else
282     ucontext_t *uc = puc;
283 #endif
284 
285     pc = PC_sig(uc);
286     return handle_cpu_signal(pc, info,
287                              TRAP_sig(uc) == 0xe ? (ERROR_sig(uc) >> 1) & 1 : 0,
288                              &MASK_sig(uc));
289 }
290 
291 #elif defined(_ARCH_PPC)
292 
293 /***********************************************************************
294  * signal context platform-specific definitions
295  * From Wine
296  */
297 #ifdef linux
298 /* All Registers access - only for local access */
299 #define REG_sig(reg_name, context)              \
300     ((context)->uc_mcontext.regs->reg_name)
301 /* Gpr Registers access  */
302 #define GPR_sig(reg_num, context)              REG_sig(gpr[reg_num], context)
303 /* Program counter */
304 #define IAR_sig(context)                       REG_sig(nip, context)
305 /* Machine State Register (Supervisor) */
306 #define MSR_sig(context)                       REG_sig(msr, context)
307 /* Count register */
308 #define CTR_sig(context)                       REG_sig(ctr, context)
309 /* User's integer exception register */
310 #define XER_sig(context)                       REG_sig(xer, context)
311 /* Link register */
312 #define LR_sig(context)                        REG_sig(link, context)
313 /* Condition register */
314 #define CR_sig(context)                        REG_sig(ccr, context)
315 
316 /* Float Registers access  */
317 #define FLOAT_sig(reg_num, context)                                     \
318     (((double *)((char *)((context)->uc_mcontext.regs + 48 * 4)))[reg_num])
319 #define FPSCR_sig(context) \
320     (*(int *)((char *)((context)->uc_mcontext.regs + (48 + 32 * 2) * 4)))
321 /* Exception Registers access */
322 #define DAR_sig(context)                       REG_sig(dar, context)
323 #define DSISR_sig(context)                     REG_sig(dsisr, context)
324 #define TRAP_sig(context)                      REG_sig(trap, context)
325 #endif /* linux */
326 
327 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
328 #include <ucontext.h>
329 #define IAR_sig(context)               ((context)->uc_mcontext.mc_srr0)
330 #define MSR_sig(context)               ((context)->uc_mcontext.mc_srr1)
331 #define CTR_sig(context)               ((context)->uc_mcontext.mc_ctr)
332 #define XER_sig(context)               ((context)->uc_mcontext.mc_xer)
333 #define LR_sig(context)                ((context)->uc_mcontext.mc_lr)
334 #define CR_sig(context)                ((context)->uc_mcontext.mc_cr)
335 /* Exception Registers access */
336 #define DAR_sig(context)               ((context)->uc_mcontext.mc_dar)
337 #define DSISR_sig(context)             ((context)->uc_mcontext.mc_dsisr)
338 #define TRAP_sig(context)              ((context)->uc_mcontext.mc_exc)
339 #endif /* __FreeBSD__|| __FreeBSD_kernel__ */
340 
341 int cpu_signal_handler(int host_signum, void *pinfo,
342                        void *puc)
343 {
344     siginfo_t *info = pinfo;
345 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
346     ucontext_t *uc = puc;
347 #else
348     ucontext_t *uc = puc;
349 #endif
350     unsigned long pc;
351     int is_write;
352 
353     pc = IAR_sig(uc);
354     is_write = 0;
355 #if 0
356     /* ppc 4xx case */
357     if (DSISR_sig(uc) & 0x00800000) {
358         is_write = 1;
359     }
360 #else
361     if (TRAP_sig(uc) != 0x400 && (DSISR_sig(uc) & 0x02000000)) {
362         is_write = 1;
363     }
364 #endif
365     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
366 }
367 
368 #elif defined(__alpha__)
369 
370 int cpu_signal_handler(int host_signum, void *pinfo,
371                            void *puc)
372 {
373     siginfo_t *info = pinfo;
374     ucontext_t *uc = puc;
375     uint32_t *pc = uc->uc_mcontext.sc_pc;
376     uint32_t insn = *pc;
377     int is_write = 0;
378 
379     /* XXX: need kernel patch to get write flag faster */
380     switch (insn >> 26) {
381     case 0x0d: /* stw */
382     case 0x0e: /* stb */
383     case 0x0f: /* stq_u */
384     case 0x24: /* stf */
385     case 0x25: /* stg */
386     case 0x26: /* sts */
387     case 0x27: /* stt */
388     case 0x2c: /* stl */
389     case 0x2d: /* stq */
390     case 0x2e: /* stl_c */
391     case 0x2f: /* stq_c */
392         is_write = 1;
393     }
394 
395     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
396 }
397 #elif defined(__sparc__)
398 
399 int cpu_signal_handler(int host_signum, void *pinfo,
400                        void *puc)
401 {
402     siginfo_t *info = pinfo;
403     int is_write;
404     uint32_t insn;
405 #if !defined(__arch64__) || defined(CONFIG_SOLARIS)
406     uint32_t *regs = (uint32_t *)(info + 1);
407     void *sigmask = (regs + 20);
408     /* XXX: is there a standard glibc define ? */
409     unsigned long pc = regs[1];
410 #else
411 #ifdef __linux__
412     struct sigcontext *sc = puc;
413     unsigned long pc = sc->sigc_regs.tpc;
414     void *sigmask = (void *)sc->sigc_mask;
415 #elif defined(__OpenBSD__)
416     struct sigcontext *uc = puc;
417     unsigned long pc = uc->sc_pc;
418     void *sigmask = (void *)(long)uc->sc_mask;
419 #elif defined(__NetBSD__)
420     ucontext_t *uc = puc;
421     unsigned long pc = _UC_MACHINE_PC(uc);
422     void *sigmask = (void *)&uc->uc_sigmask;
423 #endif
424 #endif
425 
426     /* XXX: need kernel patch to get write flag faster */
427     is_write = 0;
428     insn = *(uint32_t *)pc;
429     if ((insn >> 30) == 3) {
430         switch ((insn >> 19) & 0x3f) {
431         case 0x05: /* stb */
432         case 0x15: /* stba */
433         case 0x06: /* sth */
434         case 0x16: /* stha */
435         case 0x04: /* st */
436         case 0x14: /* sta */
437         case 0x07: /* std */
438         case 0x17: /* stda */
439         case 0x0e: /* stx */
440         case 0x1e: /* stxa */
441         case 0x24: /* stf */
442         case 0x34: /* stfa */
443         case 0x27: /* stdf */
444         case 0x37: /* stdfa */
445         case 0x26: /* stqf */
446         case 0x36: /* stqfa */
447         case 0x25: /* stfsr */
448         case 0x3c: /* casa */
449         case 0x3e: /* casxa */
450             is_write = 1;
451             break;
452         }
453     }
454     return handle_cpu_signal(pc, info, is_write, sigmask);
455 }
456 
457 #elif defined(__arm__)
458 
459 #if defined(__NetBSD__)
460 #include <ucontext.h>
461 #endif
462 
463 int cpu_signal_handler(int host_signum, void *pinfo,
464                        void *puc)
465 {
466     siginfo_t *info = pinfo;
467 #if defined(__NetBSD__)
468     ucontext_t *uc = puc;
469 #else
470     ucontext_t *uc = puc;
471 #endif
472     unsigned long pc;
473     int is_write;
474 
475 #if defined(__NetBSD__)
476     pc = uc->uc_mcontext.__gregs[_REG_R15];
477 #elif defined(__GLIBC__) && (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
478     pc = uc->uc_mcontext.gregs[R15];
479 #else
480     pc = uc->uc_mcontext.arm_pc;
481 #endif
482 
483     /* error_code is the FSR value, in which bit 11 is WnR (assuming a v6 or
484      * later processor; on v5 we will always report this as a read).
485      */
486     is_write = extract32(uc->uc_mcontext.error_code, 11, 1);
487     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
488 }
489 
490 #elif defined(__aarch64__)
491 
492 #ifndef ESR_MAGIC
493 /* Pre-3.16 kernel headers don't have these, so provide fallback definitions */
494 #define ESR_MAGIC 0x45535201
495 struct esr_context {
496     struct _aarch64_ctx head;
497     uint64_t esr;
498 };
499 #endif
500 
501 static inline struct _aarch64_ctx *first_ctx(ucontext_t *uc)
502 {
503     return (struct _aarch64_ctx *)&uc->uc_mcontext.__reserved;
504 }
505 
506 static inline struct _aarch64_ctx *next_ctx(struct _aarch64_ctx *hdr)
507 {
508     return (struct _aarch64_ctx *)((char *)hdr + hdr->size);
509 }
510 
511 int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
512 {
513     siginfo_t *info = pinfo;
514     ucontext_t *uc = puc;
515     uintptr_t pc = uc->uc_mcontext.pc;
516     bool is_write;
517     struct _aarch64_ctx *hdr;
518     struct esr_context const *esrctx = NULL;
519 
520     /* Find the esr_context, which has the WnR bit in it */
521     for (hdr = first_ctx(uc); hdr->magic; hdr = next_ctx(hdr)) {
522         if (hdr->magic == ESR_MAGIC) {
523             esrctx = (struct esr_context const *)hdr;
524             break;
525         }
526     }
527 
528     if (esrctx) {
529         /* For data aborts ESR.EC is 0b10010x: then bit 6 is the WnR bit */
530         uint64_t esr = esrctx->esr;
531         is_write = extract32(esr, 27, 5) == 0x12 && extract32(esr, 6, 1) == 1;
532     } else {
533         /*
534          * Fall back to parsing instructions; will only be needed
535          * for really ancient (pre-3.16) kernels.
536          */
537         uint32_t insn = *(uint32_t *)pc;
538 
539         is_write = ((insn & 0xbfff0000) == 0x0c000000   /* C3.3.1 */
540                     || (insn & 0xbfe00000) == 0x0c800000   /* C3.3.2 */
541                     || (insn & 0xbfdf0000) == 0x0d000000   /* C3.3.3 */
542                     || (insn & 0xbfc00000) == 0x0d800000   /* C3.3.4 */
543                     || (insn & 0x3f400000) == 0x08000000   /* C3.3.6 */
544                     || (insn & 0x3bc00000) == 0x39000000   /* C3.3.13 */
545                     || (insn & 0x3fc00000) == 0x3d800000   /* ... 128bit */
546                     /* Ignore bits 10, 11 & 21, controlling indexing.  */
547                     || (insn & 0x3bc00000) == 0x38000000   /* C3.3.8-12 */
548                     || (insn & 0x3fe00000) == 0x3c800000   /* ... 128bit */
549                     /* Ignore bits 23 & 24, controlling indexing.  */
550                     || (insn & 0x3a400000) == 0x28000000); /* C3.3.7,14-16 */
551     }
552     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
553 }
554 
555 #elif defined(__s390__)
556 
557 int cpu_signal_handler(int host_signum, void *pinfo,
558                        void *puc)
559 {
560     siginfo_t *info = pinfo;
561     ucontext_t *uc = puc;
562     unsigned long pc;
563     uint16_t *pinsn;
564     int is_write = 0;
565 
566     pc = uc->uc_mcontext.psw.addr;
567 
568     /* ??? On linux, the non-rt signal handler has 4 (!) arguments instead
569        of the normal 2 arguments.  The 3rd argument contains the "int_code"
570        from the hardware which does in fact contain the is_write value.
571        The rt signal handler, as far as I can tell, does not give this value
572        at all.  Not that we could get to it from here even if it were.  */
573     /* ??? This is not even close to complete, since it ignores all
574        of the read-modify-write instructions.  */
575     pinsn = (uint16_t *)pc;
576     switch (pinsn[0] >> 8) {
577     case 0x50: /* ST */
578     case 0x42: /* STC */
579     case 0x40: /* STH */
580         is_write = 1;
581         break;
582     case 0xc4: /* RIL format insns */
583         switch (pinsn[0] & 0xf) {
584         case 0xf: /* STRL */
585         case 0xb: /* STGRL */
586         case 0x7: /* STHRL */
587             is_write = 1;
588         }
589         break;
590     case 0xe3: /* RXY format insns */
591         switch (pinsn[2] & 0xff) {
592         case 0x50: /* STY */
593         case 0x24: /* STG */
594         case 0x72: /* STCY */
595         case 0x70: /* STHY */
596         case 0x8e: /* STPQ */
597         case 0x3f: /* STRVH */
598         case 0x3e: /* STRV */
599         case 0x2f: /* STRVG */
600             is_write = 1;
601         }
602         break;
603     }
604     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
605 }
606 
607 #elif defined(__mips__)
608 
609 int cpu_signal_handler(int host_signum, void *pinfo,
610                        void *puc)
611 {
612     siginfo_t *info = pinfo;
613     ucontext_t *uc = puc;
614     greg_t pc = uc->uc_mcontext.pc;
615     int is_write;
616 
617     /* XXX: compute is_write */
618     is_write = 0;
619     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
620 }
621 
622 #elif defined(__riscv)
623 
624 int cpu_signal_handler(int host_signum, void *pinfo,
625                        void *puc)
626 {
627     siginfo_t *info = pinfo;
628     ucontext_t *uc = puc;
629     greg_t pc = uc->uc_mcontext.__gregs[REG_PC];
630     uint32_t insn = *(uint32_t *)pc;
631     int is_write = 0;
632 
633     /* Detect store by reading the instruction at the program
634        counter. Note: we currently only generate 32-bit
635        instructions so we thus only detect 32-bit stores */
636     switch (((insn >> 0) & 0b11)) {
637     case 3:
638         switch (((insn >> 2) & 0b11111)) {
639         case 8:
640             switch (((insn >> 12) & 0b111)) {
641             case 0: /* sb */
642             case 1: /* sh */
643             case 2: /* sw */
644             case 3: /* sd */
645             case 4: /* sq */
646                 is_write = 1;
647                 break;
648             default:
649                 break;
650             }
651             break;
652         case 9:
653             switch (((insn >> 12) & 0b111)) {
654             case 2: /* fsw */
655             case 3: /* fsd */
656             case 4: /* fsq */
657                 is_write = 1;
658                 break;
659             default:
660                 break;
661             }
662             break;
663         default:
664             break;
665         }
666     }
667 
668     /* Check for compressed instructions */
669     switch (((insn >> 13) & 0b111)) {
670     case 7:
671         switch (insn & 0b11) {
672         case 0: /*c.sd */
673         case 2: /* c.sdsp */
674             is_write = 1;
675             break;
676         default:
677             break;
678         }
679         break;
680     case 6:
681         switch (insn & 0b11) {
682         case 0: /* c.sw */
683         case 3: /* c.swsp */
684             is_write = 1;
685             break;
686         default:
687             break;
688         }
689         break;
690     default:
691         break;
692     }
693 
694     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
695 }
696 
697 #else
698 
699 #error host CPU specific signal handler needed
700 
701 #endif
702 
703 /* The softmmu versions of these helpers are in cputlb.c.  */
704 
705 /* Do not allow unaligned operations to proceed.  Return the host address.  */
706 static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
707                                int size, uintptr_t retaddr)
708 {
709     /* Enforce qemu required alignment.  */
710     if (unlikely(addr & (size - 1))) {
711         cpu_loop_exit_atomic(env_cpu(env), retaddr);
712     }
713     void *ret = g2h(addr);
714     set_helper_retaddr(retaddr);
715     return ret;
716 }
717 
718 /* Macro to call the above, with local variables from the use context.  */
719 #define ATOMIC_MMU_DECLS do {} while (0)
720 #define ATOMIC_MMU_LOOKUP  atomic_mmu_lookup(env, addr, DATA_SIZE, GETPC())
721 #define ATOMIC_MMU_CLEANUP do { clear_helper_retaddr(); } while (0)
722 
723 #define ATOMIC_NAME(X)   HELPER(glue(glue(atomic_ ## X, SUFFIX), END))
724 #define EXTRA_ARGS
725 
726 #define DATA_SIZE 1
727 #include "atomic_template.h"
728 
729 #define DATA_SIZE 2
730 #include "atomic_template.h"
731 
732 #define DATA_SIZE 4
733 #include "atomic_template.h"
734 
735 #ifdef CONFIG_ATOMIC64
736 #define DATA_SIZE 8
737 #include "atomic_template.h"
738 #endif
739 
740 /* The following is only callable from other helpers, and matches up
741    with the softmmu version.  */
742 
743 #if HAVE_ATOMIC128 || HAVE_CMPXCHG128
744 
745 #undef EXTRA_ARGS
746 #undef ATOMIC_NAME
747 #undef ATOMIC_MMU_LOOKUP
748 
749 #define EXTRA_ARGS     , TCGMemOpIdx oi, uintptr_t retaddr
750 #define ATOMIC_NAME(X) \
751     HELPER(glue(glue(glue(atomic_ ## X, SUFFIX), END), _mmu))
752 #define ATOMIC_MMU_LOOKUP  atomic_mmu_lookup(env, addr, DATA_SIZE, retaddr)
753 
754 #define DATA_SIZE 16
755 #include "atomic_template.h"
756 #endif
757