xref: /openbmc/qemu/accel/tcg/user-exec.c (revision e7bbc9b1)
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     int ret;
67     unsigned long address = (unsigned long)info->si_addr;
68 
69     /* We must handle PC addresses from two different sources:
70      * a call return address and a signal frame address.
71      *
72      * Within cpu_restore_state_from_tb we assume the former and adjust
73      * the address by -GETPC_ADJ so that the address is within the call
74      * insn so that addr does not accidentally match the beginning of the
75      * next guest insn.
76      *
77      * However, when the PC comes from the signal frame, it points to
78      * the actual faulting host insn and not a call insn.  Subtracting
79      * GETPC_ADJ in that case may accidentally match the previous guest insn.
80      *
81      * So for the later case, adjust forward to compensate for what
82      * will be done later by cpu_restore_state_from_tb.
83      */
84     if (helper_retaddr) {
85         pc = helper_retaddr;
86     } else {
87         pc += GETPC_ADJ;
88     }
89 
90     /* For synchronous signals we expect to be coming from the vCPU
91      * thread (so current_cpu should be valid) and either from running
92      * code or during translation which can fault as we cross pages.
93      *
94      * If neither is true then something has gone wrong and we should
95      * abort rather than try and restart the vCPU execution.
96      */
97     if (!cpu || !cpu->running) {
98         printf("qemu:%s received signal outside vCPU context @ pc=0x%"
99                PRIxPTR "\n",  __func__, pc);
100         abort();
101     }
102 
103 #if defined(DEBUG_SIGNAL)
104     printf("qemu: SIGSEGV pc=0x%08lx address=%08lx w=%d oldset=0x%08lx\n",
105            pc, address, is_write, *(unsigned long *)old_set);
106 #endif
107     /* XXX: locking issue */
108     /* Note that it is important that we don't call page_unprotect() unless
109      * this is really a "write to nonwriteable page" fault, because
110      * page_unprotect() assumes that if it is called for an access to
111      * a page that's writeable this means we had two threads racing and
112      * another thread got there first and already made the page writeable;
113      * so we will retry the access. If we were to call page_unprotect()
114      * for some other kind of fault that should really be passed to the
115      * guest, we'd end up in an infinite loop of retrying the faulting
116      * access.
117      */
118     if (is_write && info->si_signo == SIGSEGV && info->si_code == SEGV_ACCERR &&
119         h2g_valid(address)) {
120         switch (page_unprotect(h2g(address), pc)) {
121         case 0:
122             /* Fault not caused by a page marked unwritable to protect
123              * cached translations, must be the guest binary's problem.
124              */
125             break;
126         case 1:
127             /* Fault caused by protection of cached translation; TBs
128              * invalidated, so resume execution.  Retain helper_retaddr
129              * for a possible second fault.
130              */
131             return 1;
132         case 2:
133             /* Fault caused by protection of cached translation, and the
134              * currently executing TB was modified and must be exited
135              * immediately.  Clear helper_retaddr for next execution.
136              */
137             helper_retaddr = 0;
138             cpu_exit_tb_from_sighandler(cpu, old_set);
139             /* NORETURN */
140 
141         default:
142             g_assert_not_reached();
143         }
144     }
145 
146     /* Convert forcefully to guest address space, invalid addresses
147        are still valid segv ones */
148     address = h2g_nocheck(address);
149 
150     cc = CPU_GET_CLASS(cpu);
151     /* see if it is an MMU fault */
152     g_assert(cc->handle_mmu_fault);
153     ret = cc->handle_mmu_fault(cpu, address, 0, is_write, MMU_USER_IDX);
154 
155     if (ret == 0) {
156         /* The MMU fault was handled without causing real CPU fault.
157          *  Retain helper_retaddr for a possible second fault.
158          */
159         return 1;
160     }
161 
162     /* All other paths lead to cpu_exit; clear helper_retaddr
163      * for next execution.
164      */
165     helper_retaddr = 0;
166 
167     if (ret < 0) {
168         return 0; /* not an MMU fault */
169     }
170 
171     /* Now we have a real cpu fault.  */
172     cpu_restore_state(cpu, pc, true);
173 
174     sigprocmask(SIG_SETMASK, old_set, NULL);
175     cpu_loop_exit(cpu);
176 
177     /* never comes here */
178     return 1;
179 }
180 
181 #if defined(__i386__)
182 
183 #if defined(__NetBSD__)
184 #include <ucontext.h>
185 
186 #define EIP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_EIP])
187 #define TRAP_sig(context)    ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
188 #define ERROR_sig(context)   ((context)->uc_mcontext.__gregs[_REG_ERR])
189 #define MASK_sig(context)    ((context)->uc_sigmask)
190 #elif defined(__FreeBSD__) || defined(__DragonFly__)
191 #include <ucontext.h>
192 
193 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_eip))
194 #define TRAP_sig(context)    ((context)->uc_mcontext.mc_trapno)
195 #define ERROR_sig(context)   ((context)->uc_mcontext.mc_err)
196 #define MASK_sig(context)    ((context)->uc_sigmask)
197 #elif defined(__OpenBSD__)
198 #define EIP_sig(context)     ((context)->sc_eip)
199 #define TRAP_sig(context)    ((context)->sc_trapno)
200 #define ERROR_sig(context)   ((context)->sc_err)
201 #define MASK_sig(context)    ((context)->sc_mask)
202 #else
203 #define EIP_sig(context)     ((context)->uc_mcontext.gregs[REG_EIP])
204 #define TRAP_sig(context)    ((context)->uc_mcontext.gregs[REG_TRAPNO])
205 #define ERROR_sig(context)   ((context)->uc_mcontext.gregs[REG_ERR])
206 #define MASK_sig(context)    ((context)->uc_sigmask)
207 #endif
208 
209 int cpu_signal_handler(int host_signum, void *pinfo,
210                        void *puc)
211 {
212     siginfo_t *info = pinfo;
213 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
214     ucontext_t *uc = puc;
215 #elif defined(__OpenBSD__)
216     struct sigcontext *uc = puc;
217 #else
218     ucontext_t *uc = puc;
219 #endif
220     unsigned long pc;
221     int trapno;
222 
223 #ifndef REG_EIP
224 /* for glibc 2.1 */
225 #define REG_EIP    EIP
226 #define REG_ERR    ERR
227 #define REG_TRAPNO TRAPNO
228 #endif
229     pc = EIP_sig(uc);
230     trapno = TRAP_sig(uc);
231     return handle_cpu_signal(pc, info,
232                              trapno == 0xe ? (ERROR_sig(uc) >> 1) & 1 : 0,
233                              &MASK_sig(uc));
234 }
235 
236 #elif defined(__x86_64__)
237 
238 #ifdef __NetBSD__
239 #define PC_sig(context)       _UC_MACHINE_PC(context)
240 #define TRAP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
241 #define ERROR_sig(context)    ((context)->uc_mcontext.__gregs[_REG_ERR])
242 #define MASK_sig(context)     ((context)->uc_sigmask)
243 #elif defined(__OpenBSD__)
244 #define PC_sig(context)       ((context)->sc_rip)
245 #define TRAP_sig(context)     ((context)->sc_trapno)
246 #define ERROR_sig(context)    ((context)->sc_err)
247 #define MASK_sig(context)     ((context)->sc_mask)
248 #elif defined(__FreeBSD__) || defined(__DragonFly__)
249 #include <ucontext.h>
250 
251 #define PC_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_rip))
252 #define TRAP_sig(context)     ((context)->uc_mcontext.mc_trapno)
253 #define ERROR_sig(context)    ((context)->uc_mcontext.mc_err)
254 #define MASK_sig(context)     ((context)->uc_sigmask)
255 #else
256 #define PC_sig(context)       ((context)->uc_mcontext.gregs[REG_RIP])
257 #define TRAP_sig(context)     ((context)->uc_mcontext.gregs[REG_TRAPNO])
258 #define ERROR_sig(context)    ((context)->uc_mcontext.gregs[REG_ERR])
259 #define MASK_sig(context)     ((context)->uc_sigmask)
260 #endif
261 
262 int cpu_signal_handler(int host_signum, void *pinfo,
263                        void *puc)
264 {
265     siginfo_t *info = pinfo;
266     unsigned long pc;
267 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
268     ucontext_t *uc = puc;
269 #elif defined(__OpenBSD__)
270     struct sigcontext *uc = puc;
271 #else
272     ucontext_t *uc = puc;
273 #endif
274 
275     pc = PC_sig(uc);
276     return handle_cpu_signal(pc, info,
277                              TRAP_sig(uc) == 0xe ? (ERROR_sig(uc) >> 1) & 1 : 0,
278                              &MASK_sig(uc));
279 }
280 
281 #elif defined(_ARCH_PPC)
282 
283 /***********************************************************************
284  * signal context platform-specific definitions
285  * From Wine
286  */
287 #ifdef linux
288 /* All Registers access - only for local access */
289 #define REG_sig(reg_name, context)              \
290     ((context)->uc_mcontext.regs->reg_name)
291 /* Gpr Registers access  */
292 #define GPR_sig(reg_num, context)              REG_sig(gpr[reg_num], context)
293 /* Program counter */
294 #define IAR_sig(context)                       REG_sig(nip, context)
295 /* Machine State Register (Supervisor) */
296 #define MSR_sig(context)                       REG_sig(msr, context)
297 /* Count register */
298 #define CTR_sig(context)                       REG_sig(ctr, context)
299 /* User's integer exception register */
300 #define XER_sig(context)                       REG_sig(xer, context)
301 /* Link register */
302 #define LR_sig(context)                        REG_sig(link, context)
303 /* Condition register */
304 #define CR_sig(context)                        REG_sig(ccr, context)
305 
306 /* Float Registers access  */
307 #define FLOAT_sig(reg_num, context)                                     \
308     (((double *)((char *)((context)->uc_mcontext.regs + 48 * 4)))[reg_num])
309 #define FPSCR_sig(context) \
310     (*(int *)((char *)((context)->uc_mcontext.regs + (48 + 32 * 2) * 4)))
311 /* Exception Registers access */
312 #define DAR_sig(context)                       REG_sig(dar, context)
313 #define DSISR_sig(context)                     REG_sig(dsisr, context)
314 #define TRAP_sig(context)                      REG_sig(trap, context)
315 #endif /* linux */
316 
317 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
318 #include <ucontext.h>
319 #define IAR_sig(context)               ((context)->uc_mcontext.mc_srr0)
320 #define MSR_sig(context)               ((context)->uc_mcontext.mc_srr1)
321 #define CTR_sig(context)               ((context)->uc_mcontext.mc_ctr)
322 #define XER_sig(context)               ((context)->uc_mcontext.mc_xer)
323 #define LR_sig(context)                ((context)->uc_mcontext.mc_lr)
324 #define CR_sig(context)                ((context)->uc_mcontext.mc_cr)
325 /* Exception Registers access */
326 #define DAR_sig(context)               ((context)->uc_mcontext.mc_dar)
327 #define DSISR_sig(context)             ((context)->uc_mcontext.mc_dsisr)
328 #define TRAP_sig(context)              ((context)->uc_mcontext.mc_exc)
329 #endif /* __FreeBSD__|| __FreeBSD_kernel__ */
330 
331 int cpu_signal_handler(int host_signum, void *pinfo,
332                        void *puc)
333 {
334     siginfo_t *info = pinfo;
335 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
336     ucontext_t *uc = puc;
337 #else
338     ucontext_t *uc = puc;
339 #endif
340     unsigned long pc;
341     int is_write;
342 
343     pc = IAR_sig(uc);
344     is_write = 0;
345 #if 0
346     /* ppc 4xx case */
347     if (DSISR_sig(uc) & 0x00800000) {
348         is_write = 1;
349     }
350 #else
351     if (TRAP_sig(uc) != 0x400 && (DSISR_sig(uc) & 0x02000000)) {
352         is_write = 1;
353     }
354 #endif
355     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
356 }
357 
358 #elif defined(__alpha__)
359 
360 int cpu_signal_handler(int host_signum, void *pinfo,
361                            void *puc)
362 {
363     siginfo_t *info = pinfo;
364     ucontext_t *uc = puc;
365     uint32_t *pc = uc->uc_mcontext.sc_pc;
366     uint32_t insn = *pc;
367     int is_write = 0;
368 
369     /* XXX: need kernel patch to get write flag faster */
370     switch (insn >> 26) {
371     case 0x0d: /* stw */
372     case 0x0e: /* stb */
373     case 0x0f: /* stq_u */
374     case 0x24: /* stf */
375     case 0x25: /* stg */
376     case 0x26: /* sts */
377     case 0x27: /* stt */
378     case 0x2c: /* stl */
379     case 0x2d: /* stq */
380     case 0x2e: /* stl_c */
381     case 0x2f: /* stq_c */
382         is_write = 1;
383     }
384 
385     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
386 }
387 #elif defined(__sparc__)
388 
389 int cpu_signal_handler(int host_signum, void *pinfo,
390                        void *puc)
391 {
392     siginfo_t *info = pinfo;
393     int is_write;
394     uint32_t insn;
395 #if !defined(__arch64__) || defined(CONFIG_SOLARIS)
396     uint32_t *regs = (uint32_t *)(info + 1);
397     void *sigmask = (regs + 20);
398     /* XXX: is there a standard glibc define ? */
399     unsigned long pc = regs[1];
400 #else
401 #ifdef __linux__
402     struct sigcontext *sc = puc;
403     unsigned long pc = sc->sigc_regs.tpc;
404     void *sigmask = (void *)sc->sigc_mask;
405 #elif defined(__OpenBSD__)
406     struct sigcontext *uc = puc;
407     unsigned long pc = uc->sc_pc;
408     void *sigmask = (void *)(long)uc->sc_mask;
409 #elif defined(__NetBSD__)
410     ucontext_t *uc = puc;
411     unsigned long pc = _UC_MACHINE_PC(uc);
412     void *sigmask = (void *)&uc->uc_sigmask;
413 #endif
414 #endif
415 
416     /* XXX: need kernel patch to get write flag faster */
417     is_write = 0;
418     insn = *(uint32_t *)pc;
419     if ((insn >> 30) == 3) {
420         switch ((insn >> 19) & 0x3f) {
421         case 0x05: /* stb */
422         case 0x15: /* stba */
423         case 0x06: /* sth */
424         case 0x16: /* stha */
425         case 0x04: /* st */
426         case 0x14: /* sta */
427         case 0x07: /* std */
428         case 0x17: /* stda */
429         case 0x0e: /* stx */
430         case 0x1e: /* stxa */
431         case 0x24: /* stf */
432         case 0x34: /* stfa */
433         case 0x27: /* stdf */
434         case 0x37: /* stdfa */
435         case 0x26: /* stqf */
436         case 0x36: /* stqfa */
437         case 0x25: /* stfsr */
438         case 0x3c: /* casa */
439         case 0x3e: /* casxa */
440             is_write = 1;
441             break;
442         }
443     }
444     return handle_cpu_signal(pc, info, is_write, sigmask);
445 }
446 
447 #elif defined(__arm__)
448 
449 #if defined(__NetBSD__)
450 #include <ucontext.h>
451 #endif
452 
453 int cpu_signal_handler(int host_signum, void *pinfo,
454                        void *puc)
455 {
456     siginfo_t *info = pinfo;
457 #if defined(__NetBSD__)
458     ucontext_t *uc = puc;
459 #else
460     ucontext_t *uc = puc;
461 #endif
462     unsigned long pc;
463     int is_write;
464 
465 #if defined(__NetBSD__)
466     pc = uc->uc_mcontext.__gregs[_REG_R15];
467 #elif defined(__GLIBC__) && (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
468     pc = uc->uc_mcontext.gregs[R15];
469 #else
470     pc = uc->uc_mcontext.arm_pc;
471 #endif
472 
473     /* error_code is the FSR value, in which bit 11 is WnR (assuming a v6 or
474      * later processor; on v5 we will always report this as a read).
475      */
476     is_write = extract32(uc->uc_mcontext.error_code, 11, 1);
477     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
478 }
479 
480 #elif defined(__aarch64__)
481 
482 #ifndef ESR_MAGIC
483 /* Pre-3.16 kernel headers don't have these, so provide fallback definitions */
484 #define ESR_MAGIC 0x45535201
485 struct esr_context {
486     struct _aarch64_ctx head;
487     uint64_t esr;
488 };
489 #endif
490 
491 static inline struct _aarch64_ctx *first_ctx(ucontext_t *uc)
492 {
493     return (struct _aarch64_ctx *)&uc->uc_mcontext.__reserved;
494 }
495 
496 static inline struct _aarch64_ctx *next_ctx(struct _aarch64_ctx *hdr)
497 {
498     return (struct _aarch64_ctx *)((char *)hdr + hdr->size);
499 }
500 
501 int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
502 {
503     siginfo_t *info = pinfo;
504     ucontext_t *uc = puc;
505     uintptr_t pc = uc->uc_mcontext.pc;
506     bool is_write;
507     struct _aarch64_ctx *hdr;
508     struct esr_context const *esrctx = NULL;
509 
510     /* Find the esr_context, which has the WnR bit in it */
511     for (hdr = first_ctx(uc); hdr->magic; hdr = next_ctx(hdr)) {
512         if (hdr->magic == ESR_MAGIC) {
513             esrctx = (struct esr_context const *)hdr;
514             break;
515         }
516     }
517 
518     if (esrctx) {
519         /* For data aborts ESR.EC is 0b10010x: then bit 6 is the WnR bit */
520         uint64_t esr = esrctx->esr;
521         is_write = extract32(esr, 27, 5) == 0x12 && extract32(esr, 6, 1) == 1;
522     } else {
523         /*
524          * Fall back to parsing instructions; will only be needed
525          * for really ancient (pre-3.16) kernels.
526          */
527         uint32_t insn = *(uint32_t *)pc;
528 
529         is_write = ((insn & 0xbfff0000) == 0x0c000000   /* C3.3.1 */
530                     || (insn & 0xbfe00000) == 0x0c800000   /* C3.3.2 */
531                     || (insn & 0xbfdf0000) == 0x0d000000   /* C3.3.3 */
532                     || (insn & 0xbfc00000) == 0x0d800000   /* C3.3.4 */
533                     || (insn & 0x3f400000) == 0x08000000   /* C3.3.6 */
534                     || (insn & 0x3bc00000) == 0x39000000   /* C3.3.13 */
535                     || (insn & 0x3fc00000) == 0x3d800000   /* ... 128bit */
536                     /* Ignore bits 10, 11 & 21, controlling indexing.  */
537                     || (insn & 0x3bc00000) == 0x38000000   /* C3.3.8-12 */
538                     || (insn & 0x3fe00000) == 0x3c800000   /* ... 128bit */
539                     /* Ignore bits 23 & 24, controlling indexing.  */
540                     || (insn & 0x3a400000) == 0x28000000); /* C3.3.7,14-16 */
541     }
542     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
543 }
544 
545 #elif defined(__s390__)
546 
547 int cpu_signal_handler(int host_signum, void *pinfo,
548                        void *puc)
549 {
550     siginfo_t *info = pinfo;
551     ucontext_t *uc = puc;
552     unsigned long pc;
553     uint16_t *pinsn;
554     int is_write = 0;
555 
556     pc = uc->uc_mcontext.psw.addr;
557 
558     /* ??? On linux, the non-rt signal handler has 4 (!) arguments instead
559        of the normal 2 arguments.  The 3rd argument contains the "int_code"
560        from the hardware which does in fact contain the is_write value.
561        The rt signal handler, as far as I can tell, does not give this value
562        at all.  Not that we could get to it from here even if it were.  */
563     /* ??? This is not even close to complete, since it ignores all
564        of the read-modify-write instructions.  */
565     pinsn = (uint16_t *)pc;
566     switch (pinsn[0] >> 8) {
567     case 0x50: /* ST */
568     case 0x42: /* STC */
569     case 0x40: /* STH */
570         is_write = 1;
571         break;
572     case 0xc4: /* RIL format insns */
573         switch (pinsn[0] & 0xf) {
574         case 0xf: /* STRL */
575         case 0xb: /* STGRL */
576         case 0x7: /* STHRL */
577             is_write = 1;
578         }
579         break;
580     case 0xe3: /* RXY format insns */
581         switch (pinsn[2] & 0xff) {
582         case 0x50: /* STY */
583         case 0x24: /* STG */
584         case 0x72: /* STCY */
585         case 0x70: /* STHY */
586         case 0x8e: /* STPQ */
587         case 0x3f: /* STRVH */
588         case 0x3e: /* STRV */
589         case 0x2f: /* STRVG */
590             is_write = 1;
591         }
592         break;
593     }
594     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
595 }
596 
597 #elif defined(__mips__)
598 
599 int cpu_signal_handler(int host_signum, void *pinfo,
600                        void *puc)
601 {
602     siginfo_t *info = pinfo;
603     ucontext_t *uc = puc;
604     greg_t pc = uc->uc_mcontext.pc;
605     int is_write;
606 
607     /* XXX: compute is_write */
608     is_write = 0;
609     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
610 }
611 
612 #elif defined(__riscv)
613 
614 int cpu_signal_handler(int host_signum, void *pinfo,
615                        void *puc)
616 {
617     siginfo_t *info = pinfo;
618     ucontext_t *uc = puc;
619     greg_t pc = uc->uc_mcontext.__gregs[REG_PC];
620     uint32_t insn = *(uint32_t *)pc;
621     int is_write = 0;
622 
623     /* Detect store by reading the instruction at the program
624        counter. Note: we currently only generate 32-bit
625        instructions so we thus only detect 32-bit stores */
626     switch (((insn >> 0) & 0b11)) {
627     case 3:
628         switch (((insn >> 2) & 0b11111)) {
629         case 8:
630             switch (((insn >> 12) & 0b111)) {
631             case 0: /* sb */
632             case 1: /* sh */
633             case 2: /* sw */
634             case 3: /* sd */
635             case 4: /* sq */
636                 is_write = 1;
637                 break;
638             default:
639                 break;
640             }
641             break;
642         case 9:
643             switch (((insn >> 12) & 0b111)) {
644             case 2: /* fsw */
645             case 3: /* fsd */
646             case 4: /* fsq */
647                 is_write = 1;
648                 break;
649             default:
650                 break;
651             }
652             break;
653         default:
654             break;
655         }
656     }
657 
658     /* Check for compressed instructions */
659     switch (((insn >> 13) & 0b111)) {
660     case 7:
661         switch (insn & 0b11) {
662         case 0: /*c.sd */
663         case 2: /* c.sdsp */
664             is_write = 1;
665             break;
666         default:
667             break;
668         }
669         break;
670     case 6:
671         switch (insn & 0b11) {
672         case 0: /* c.sw */
673         case 3: /* c.swsp */
674             is_write = 1;
675             break;
676         default:
677             break;
678         }
679         break;
680     default:
681         break;
682     }
683 
684     return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
685 }
686 
687 #else
688 
689 #error host CPU specific signal handler needed
690 
691 #endif
692 
693 /* The softmmu versions of these helpers are in cputlb.c.  */
694 
695 /* Do not allow unaligned operations to proceed.  Return the host address.  */
696 static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
697                                int size, uintptr_t retaddr)
698 {
699     /* Enforce qemu required alignment.  */
700     if (unlikely(addr & (size - 1))) {
701         cpu_loop_exit_atomic(ENV_GET_CPU(env), retaddr);
702     }
703     helper_retaddr = retaddr;
704     return g2h(addr);
705 }
706 
707 /* Macro to call the above, with local variables from the use context.  */
708 #define ATOMIC_MMU_DECLS do {} while (0)
709 #define ATOMIC_MMU_LOOKUP  atomic_mmu_lookup(env, addr, DATA_SIZE, GETPC())
710 #define ATOMIC_MMU_CLEANUP do { helper_retaddr = 0; } while (0)
711 
712 #define ATOMIC_NAME(X)   HELPER(glue(glue(atomic_ ## X, SUFFIX), END))
713 #define EXTRA_ARGS
714 
715 #define DATA_SIZE 1
716 #include "atomic_template.h"
717 
718 #define DATA_SIZE 2
719 #include "atomic_template.h"
720 
721 #define DATA_SIZE 4
722 #include "atomic_template.h"
723 
724 #ifdef CONFIG_ATOMIC64
725 #define DATA_SIZE 8
726 #include "atomic_template.h"
727 #endif
728 
729 /* The following is only callable from other helpers, and matches up
730    with the softmmu version.  */
731 
732 #if HAVE_ATOMIC128 || HAVE_CMPXCHG128
733 
734 #undef EXTRA_ARGS
735 #undef ATOMIC_NAME
736 #undef ATOMIC_MMU_LOOKUP
737 
738 #define EXTRA_ARGS     , TCGMemOpIdx oi, uintptr_t retaddr
739 #define ATOMIC_NAME(X) \
740     HELPER(glue(glue(glue(atomic_ ## X, SUFFIX), END), _mmu))
741 #define ATOMIC_MMU_LOOKUP  atomic_mmu_lookup(env, addr, DATA_SIZE, retaddr)
742 
743 #define DATA_SIZE 16
744 #include "atomic_template.h"
745 #endif
746