user-exec.c

   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 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 "config.h"
  20 #include "cpu.h"
  21 #include "disas/disas.h"
  22 #include "tcg.h"
  23 #include "qemu/bitops.h"
  24 #include "exec/cpu_ldst.h"
  25 #include "translate-all.h"
  26
  27 #undef EAX
  28 #undef ECX
  29 #undef EDX
  30 #undef EBX
  31 #undef ESP
  32 #undef EBP
  33 #undef ESI
  34 #undef EDI
  35 #undef EIP
  36 #include <signal.h>
  37 #ifdef __linux__
  38 #include <sys/ucontext.h>
  39 #endif
  40
  41 //#define DEBUG_SIGNAL
  42
  43 static void exception_action(CPUState *cpu)
  44 {
  45 #if defined(TARGET_I386)
  46     X86CPU *x86_cpu = X86_CPU(cpu);
  47     CPUX86State *env1 = &x86_cpu->env;
  48
  49     raise_exception_err(env1, cpu->exception_index, env1->error_code);
  50 #else
  51     cpu_loop_exit(cpu);
  52 #endif
  53 }
  54
  55 /* exit the current TB from a signal handler. The host registers are
  56    restored in a state compatible with the CPU emulator
  57  */
  58 void cpu_resume_from_signal(CPUState *cpu, void *puc)
  59 {
  60 #ifdef __linux__
  61     struct ucontext *uc = puc;
  62 #elif defined(__OpenBSD__)
  63     struct sigcontext *uc = puc;
  64 #endif
  65
  66     if (puc) {
  67         /* XXX: use siglongjmp ? */
  68 #ifdef __linux__
  69 #ifdef __ia64
  70         sigprocmask(SIG_SETMASK, (sigset_t *)&uc->uc_sigmask, NULL);
  71 #else
  72         sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
  73 #endif
  74 #elif defined(__OpenBSD__)
  75         sigprocmask(SIG_SETMASK, &uc->sc_mask, NULL);
  76 #endif
  77     }
  78     cpu->exception_index = -1;
  79     siglongjmp(cpu->jmp_env, 1);
  80 }
  81
  82 /* 'pc' is the host PC at which the exception was raised. 'address' is
  83    the effective address of the memory exception. 'is_write' is 1 if a
  84    write caused the exception and otherwise 0'. 'old_set' is the
  85    signal set which should be restored */
  86 static inline int handle_cpu_signal(uintptr_t pc, unsigned long address,
  87                                     int is_write, sigset_t *old_set,
  88                                     void *puc)
  89 {
  90     CPUState *cpu;
  91     CPUClass *cc;
  92     int ret;
  93
  94 #if defined(DEBUG_SIGNAL)
  95     printf("qemu: SIGSEGV pc=0x%08lx address=%08lx w=%d oldset=0x%08lx\n",
  96            pc, address, is_write, *(unsigned long *)old_set);
  97 #endif
  98     /* XXX: locking issue */
  99     if (is_write && h2g_valid(address)
 100         && page_unprotect(h2g(address), pc, puc)) {
 101         return 1;
 102     }
 103
 104     /* Convert forcefully to guest address space, invalid addresses
 105        are still valid segv ones */
 106     address = h2g_nocheck(address);
 107
 108     cpu = current_cpu;
 109     cc = CPU_GET_CLASS(cpu);
 110     /* see if it is an MMU fault */
 111     g_assert(cc->handle_mmu_fault);
 112     ret = cc->handle_mmu_fault(cpu, address, is_write, MMU_USER_IDX);
 113     if (ret < 0) {
 114         return 0; /* not an MMU fault */
 115     }
 116     if (ret == 0) {
 117         return 1; /* the MMU fault was handled without causing real CPU fault */
 118     }
 119     /* now we have a real cpu fault */
 120     cpu_restore_state(cpu, pc);
 121
 122     /* we restore the process signal mask as the sigreturn should
 123        do it (XXX: use sigsetjmp) */
 124     sigprocmask(SIG_SETMASK, old_set, NULL);
 125     exception_action(cpu);
 126
 127     /* never comes here */
 128     return 1;
 129 }
 130
 131 #if defined(__i386__)
 132
 133 #if defined(__APPLE__)
 134 #include <sys/ucontext.h>
 135
 136 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext->ss.eip))
 137 #define TRAP_sig(context)    ((context)->uc_mcontext->es.trapno)
 138 #define ERROR_sig(context)   ((context)->uc_mcontext->es.err)
 139 #define MASK_sig(context)    ((context)->uc_sigmask)
 140 #elif defined(__NetBSD__)
 141 #include <ucontext.h>
 142
 143 #define EIP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_EIP])
 144 #define TRAP_sig(context)    ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
 145 #define ERROR_sig(context)   ((context)->uc_mcontext.__gregs[_REG_ERR])
 146 #define MASK_sig(context)    ((context)->uc_sigmask)
 147 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 148 #include <ucontext.h>
 149
 150 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_eip))
 151 #define TRAP_sig(context)    ((context)->uc_mcontext.mc_trapno)
 152 #define ERROR_sig(context)   ((context)->uc_mcontext.mc_err)
 153 #define MASK_sig(context)    ((context)->uc_sigmask)
 154 #elif defined(__OpenBSD__)
 155 #define EIP_sig(context)     ((context)->sc_eip)
 156 #define TRAP_sig(context)    ((context)->sc_trapno)
 157 #define ERROR_sig(context)   ((context)->sc_err)
 158 #define MASK_sig(context)    ((context)->sc_mask)
 159 #else
 160 #define EIP_sig(context)     ((context)->uc_mcontext.gregs[REG_EIP])
 161 #define TRAP_sig(context)    ((context)->uc_mcontext.gregs[REG_TRAPNO])
 162 #define ERROR_sig(context)   ((context)->uc_mcontext.gregs[REG_ERR])
 163 #define MASK_sig(context)    ((context)->uc_sigmask)
 164 #endif
 165
 166 int cpu_signal_handler(int host_signum, void *pinfo,
 167                        void *puc)
 168 {
 169     siginfo_t *info = pinfo;
 170 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
 171     ucontext_t *uc = puc;
 172 #elif defined(__OpenBSD__)
 173     struct sigcontext *uc = puc;
 174 #else
 175     struct ucontext *uc = puc;
 176 #endif
 177     unsigned long pc;
 178     int trapno;
 179
 180 #ifndef REG_EIP
 181 /* for glibc 2.1 */
 182 #define REG_EIP    EIP
 183 #define REG_ERR    ERR
 184 #define REG_TRAPNO TRAPNO
 185 #endif
 186     pc = EIP_sig(uc);
 187     trapno = TRAP_sig(uc);
 188     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 189                              trapno == 0xe ?
 190                              (ERROR_sig(uc) >> 1) & 1 : 0,
 191                              &MASK_sig(uc), puc);
 192 }
 193
 194 #elif defined(__x86_64__)
 195
 196 #ifdef __NetBSD__
 197 #define PC_sig(context)       _UC_MACHINE_PC(context)
 198 #define TRAP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
 199 #define ERROR_sig(context)    ((context)->uc_mcontext.__gregs[_REG_ERR])
 200 #define MASK_sig(context)     ((context)->uc_sigmask)
 201 #elif defined(__OpenBSD__)
 202 #define PC_sig(context)       ((context)->sc_rip)
 203 #define TRAP_sig(context)     ((context)->sc_trapno)
 204 #define ERROR_sig(context)    ((context)->sc_err)
 205 #define MASK_sig(context)     ((context)->sc_mask)
 206 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 207 #include <ucontext.h>
 208
 209 #define PC_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_rip))
 210 #define TRAP_sig(context)     ((context)->uc_mcontext.mc_trapno)
 211 #define ERROR_sig(context)    ((context)->uc_mcontext.mc_err)
 212 #define MASK_sig(context)     ((context)->uc_sigmask)
 213 #else
 214 #define PC_sig(context)       ((context)->uc_mcontext.gregs[REG_RIP])
 215 #define TRAP_sig(context)     ((context)->uc_mcontext.gregs[REG_TRAPNO])
 216 #define ERROR_sig(context)    ((context)->uc_mcontext.gregs[REG_ERR])
 217 #define MASK_sig(context)     ((context)->uc_sigmask)
 218 #endif
 219
 220 int cpu_signal_handler(int host_signum, void *pinfo,
 221                        void *puc)
 222 {
 223     siginfo_t *info = pinfo;
 224     unsigned long pc;
 225 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
 226     ucontext_t *uc = puc;
 227 #elif defined(__OpenBSD__)
 228     struct sigcontext *uc = puc;
 229 #else
 230     struct ucontext *uc = puc;
 231 #endif
 232
 233     pc = PC_sig(uc);
 234     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 235                              TRAP_sig(uc) == 0xe ?
 236                              (ERROR_sig(uc) >> 1) & 1 : 0,
 237                              &MASK_sig(uc), puc);
 238 }
 239
 240 #elif defined(_ARCH_PPC)
 241
 242 /***********************************************************************
 243  * signal context platform-specific definitions
 244  * From Wine
 245  */
 246 #ifdef linux
 247 /* All Registers access - only for local access */
 248 #define REG_sig(reg_name, context)              \
 249     ((context)->uc_mcontext.regs->reg_name)
 250 /* Gpr Registers access  */
 251 #define GPR_sig(reg_num, context)              REG_sig(gpr[reg_num], context)
 252 /* Program counter */
 253 #define IAR_sig(context)                       REG_sig(nip, context)
 254 /* Machine State Register (Supervisor) */
 255 #define MSR_sig(context)                       REG_sig(msr, context)
 256 /* Count register */
 257 #define CTR_sig(context)                       REG_sig(ctr, context)
 258 /* User's integer exception register */
 259 #define XER_sig(context)                       REG_sig(xer, context)
 260 /* Link register */
 261 #define LR_sig(context)                        REG_sig(link, context)
 262 /* Condition register */
 263 #define CR_sig(context)                        REG_sig(ccr, context)
 264
 265 /* Float Registers access  */
 266 #define FLOAT_sig(reg_num, context)                                     \
 267     (((double *)((char *)((context)->uc_mcontext.regs + 48 * 4)))[reg_num])
 268 #define FPSCR_sig(context) \
 269     (*(int *)((char *)((context)->uc_mcontext.regs + (48 + 32 * 2) * 4)))
 270 /* Exception Registers access */
 271 #define DAR_sig(context)                       REG_sig(dar, context)
 272 #define DSISR_sig(context)                     REG_sig(dsisr, context)
 273 #define TRAP_sig(context)                      REG_sig(trap, context)
 274 #endif /* linux */
 275
 276 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 277 #include <ucontext.h>
 278 #define IAR_sig(context)               ((context)->uc_mcontext.mc_srr0)
 279 #define MSR_sig(context)               ((context)->uc_mcontext.mc_srr1)
 280 #define CTR_sig(context)               ((context)->uc_mcontext.mc_ctr)
 281 #define XER_sig(context)               ((context)->uc_mcontext.mc_xer)
 282 #define LR_sig(context)                ((context)->uc_mcontext.mc_lr)
 283 #define CR_sig(context)                ((context)->uc_mcontext.mc_cr)
 284 /* Exception Registers access */
 285 #define DAR_sig(context)               ((context)->uc_mcontext.mc_dar)
 286 #define DSISR_sig(context)             ((context)->uc_mcontext.mc_dsisr)
 287 #define TRAP_sig(context)              ((context)->uc_mcontext.mc_exc)
 288 #endif /* __FreeBSD__|| __FreeBSD_kernel__ */
 289
 290 #ifdef __APPLE__
 291 #include <sys/ucontext.h>
 292 typedef struct ucontext SIGCONTEXT;
 293 /* All Registers access - only for local access */
 294 #define REG_sig(reg_name, context)              \
 295     ((context)->uc_mcontext->ss.reg_name)
 296 #define FLOATREG_sig(reg_name, context)         \
 297     ((context)->uc_mcontext->fs.reg_name)
 298 #define EXCEPREG_sig(reg_name, context)         \
 299     ((context)->uc_mcontext->es.reg_name)
 300 #define VECREG_sig(reg_name, context)           \
 301     ((context)->uc_mcontext->vs.reg_name)
 302 /* Gpr Registers access */
 303 #define GPR_sig(reg_num, context)              REG_sig(r##reg_num, context)
 304 /* Program counter */
 305 #define IAR_sig(context)                       REG_sig(srr0, context)
 306 /* Machine State Register (Supervisor) */
 307 #define MSR_sig(context)                       REG_sig(srr1, context)
 308 #define CTR_sig(context)                       REG_sig(ctr, context)
 309 /* Link register */
 310 #define XER_sig(context)                       REG_sig(xer, context)
 311 /* User's integer exception register */
 312 #define LR_sig(context)                        REG_sig(lr, context)
 313 /* Condition register */
 314 #define CR_sig(context)                        REG_sig(cr, context)
 315 /* Float Registers access */
 316 #define FLOAT_sig(reg_num, context)             \
 317     FLOATREG_sig(fpregs[reg_num], context)
 318 #define FPSCR_sig(context)                      \
 319     ((double)FLOATREG_sig(fpscr, context))
 320 /* Exception Registers access */
 321 /* Fault registers for coredump */
 322 #define DAR_sig(context)                       EXCEPREG_sig(dar, context)
 323 #define DSISR_sig(context)                     EXCEPREG_sig(dsisr, context)
 324 /* number of powerpc exception taken */
 325 #define TRAP_sig(context)                      EXCEPREG_sig(exception, context)
 326 #endif /* __APPLE__ */
 327
 328 int cpu_signal_handler(int host_signum, void *pinfo,
 329                        void *puc)
 330 {
 331     siginfo_t *info = pinfo;
 332 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 333     ucontext_t *uc = puc;
 334 #else
 335     struct ucontext *uc = puc;
 336 #endif
 337     unsigned long pc;
 338     int is_write;
 339
 340     pc = IAR_sig(uc);
 341     is_write = 0;
 342 #if 0
 343     /* ppc 4xx case */
 344     if (DSISR_sig(uc) & 0x00800000) {
 345         is_write = 1;
 346     }
 347 #else
 348     if (TRAP_sig(uc) != 0x400 && (DSISR_sig(uc) & 0x02000000)) {
 349         is_write = 1;
 350     }
 351 #endif
 352     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 353                              is_write, &uc->uc_sigmask, puc);
 354 }
 355
 356 #elif defined(__alpha__)
 357
 358 int cpu_signal_handler(int host_signum, void *pinfo,
 359                            void *puc)
 360 {
 361     siginfo_t *info = pinfo;
 362     struct ucontext *uc = puc;
 363     uint32_t *pc = uc->uc_mcontext.sc_pc;
 364     uint32_t insn = *pc;
 365     int is_write = 0;
 366
 367     /* XXX: need kernel patch to get write flag faster */
 368     switch (insn >> 26) {
 369     case 0x0d: /* stw */
 370     case 0x0e: /* stb */
 371     case 0x0f: /* stq_u */
 372     case 0x24: /* stf */
 373     case 0x25: /* stg */
 374     case 0x26: /* sts */
 375     case 0x27: /* stt */
 376     case 0x2c: /* stl */
 377     case 0x2d: /* stq */
 378     case 0x2e: /* stl_c */
 379     case 0x2f: /* stq_c */
 380         is_write = 1;
 381     }
 382
 383     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 384                              is_write, &uc->uc_sigmask, puc);
 385 }
 386 #elif defined(__sparc__)
 387
 388 int cpu_signal_handler(int host_signum, void *pinfo,
 389                        void *puc)
 390 {
 391     siginfo_t *info = pinfo;
 392     int is_write;
 393     uint32_t insn;
 394 #if !defined(__arch64__) || defined(CONFIG_SOLARIS)
 395     uint32_t *regs = (uint32_t *)(info + 1);
 396     void *sigmask = (regs + 20);
 397     /* XXX: is there a standard glibc define ? */
 398     unsigned long pc = regs[1];
 399 #else
 400 #ifdef __linux__
 401     struct sigcontext *sc = puc;
 402     unsigned long pc = sc->sigc_regs.tpc;
 403     void *sigmask = (void *)sc->sigc_mask;
 404 #elif defined(__OpenBSD__)
 405     struct sigcontext *uc = puc;
 406     unsigned long pc = uc->sc_pc;
 407     void *sigmask = (void *)(long)uc->sc_mask;
 408 #elif defined(__NetBSD__)
 409     ucontext_t *uc = puc;
 410     unsigned long pc = _UC_MACHINE_PC(uc);
 411     void *sigmask = (void *)&uc->uc_sigmask;
 412 #endif
 413 #endif
 414
 415     /* XXX: need kernel patch to get write flag faster */
 416     is_write = 0;
 417     insn = *(uint32_t *)pc;
 418     if ((insn >> 30) == 3) {
 419         switch ((insn >> 19) & 0x3f) {
 420         case 0x05: /* stb */
 421         case 0x15: /* stba */
 422         case 0x06: /* sth */
 423         case 0x16: /* stha */
 424         case 0x04: /* st */
 425         case 0x14: /* sta */
 426         case 0x07: /* std */
 427         case 0x17: /* stda */
 428         case 0x0e: /* stx */
 429         case 0x1e: /* stxa */
 430         case 0x24: /* stf */
 431         case 0x34: /* stfa */
 432         case 0x27: /* stdf */
 433         case 0x37: /* stdfa */
 434         case 0x26: /* stqf */
 435         case 0x36: /* stqfa */
 436         case 0x25: /* stfsr */
 437         case 0x3c: /* casa */
 438         case 0x3e: /* casxa */
 439             is_write = 1;
 440             break;
 441         }
 442     }
 443     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 444                              is_write, sigmask, NULL);
 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     struct ucontext *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, (unsigned long)info->si_addr,
 478                              is_write,
 479                              &uc->uc_sigmask, puc);
 480 }
 481
 482 #elif defined(__aarch64__)
 483
 484 int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
 485 {
 486     siginfo_t *info = pinfo;
 487     struct ucontext *uc = puc;
 488     uintptr_t pc = uc->uc_mcontext.pc;
 489     uint32_t insn = *(uint32_t *)pc;
 490     bool is_write;
 491
 492     /* XXX: need kernel patch to get write flag faster.  */
 493     is_write = (   (insn & 0xbfff0000) == 0x0c000000   /* C3.3.1 */
 494                 || (insn & 0xbfe00000) == 0x0c800000   /* C3.3.2 */
 495                 || (insn & 0xbfdf0000) == 0x0d000000   /* C3.3.3 */
 496                 || (insn & 0xbfc00000) == 0x0d800000   /* C3.3.4 */
 497                 || (insn & 0x3f400000) == 0x08000000   /* C3.3.6 */
 498                 || (insn & 0x3bc00000) == 0x39000000   /* C3.3.13 */
 499                 || (insn & 0x3fc00000) == 0x3d800000   /* ... 128bit */
 500                 /* Ingore bits 10, 11 & 21, controlling indexing.  */
 501                 || (insn & 0x3bc00000) == 0x38000000   /* C3.3.8-12 */
 502                 || (insn & 0x3fe00000) == 0x3c800000   /* ... 128bit */
 503                 /* Ignore bits 23 & 24, controlling indexing.  */
 504                 || (insn & 0x3a400000) == 0x28000000); /* C3.3.7,14-16 */
 505
 506     return handle_cpu_signal(pc, (uintptr_t)info->si_addr,
 507                              is_write, &uc->uc_sigmask, puc);
 508 }
 509
 510 #elif defined(__mc68000)
 511
 512 int cpu_signal_handler(int host_signum, void *pinfo,
 513                        void *puc)
 514 {
 515     siginfo_t *info = pinfo;
 516     struct ucontext *uc = puc;
 517     unsigned long pc;
 518     int is_write;
 519
 520     pc = uc->uc_mcontext.gregs[16];
 521     /* XXX: compute is_write */
 522     is_write = 0;
 523     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 524                              is_write,
 525                              &uc->uc_sigmask, puc);
 526 }
 527
 528 #elif defined(__ia64)
 529
 530 #ifndef __ISR_VALID
 531   /* This ought to be in <bits/siginfo.h>... */
 532 # define __ISR_VALID    1
 533 #endif
 534
 535 int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
 536 {
 537     siginfo_t *info = pinfo;
 538     struct ucontext *uc = puc;
 539     unsigned long ip;
 540     int is_write = 0;
 541
 542     ip = uc->uc_mcontext.sc_ip;
 543     switch (host_signum) {
 544     case SIGILL:
 545     case SIGFPE:
 546     case SIGSEGV:
 547     case SIGBUS:
 548     case SIGTRAP:
 549         if (info->si_code && (info->si_segvflags & __ISR_VALID)) {
 550             /* ISR.W (write-access) is bit 33:  */
 551             is_write = (info->si_isr >> 33) & 1;
 552         }
 553         break;
 554
 555     default:
 556         break;
 557     }
 558     return handle_cpu_signal(ip, (unsigned long)info->si_addr,
 559                              is_write,
 560                              (sigset_t *)&uc->uc_sigmask, puc);
 561 }
 562
 563 #elif defined(__s390__)
 564
 565 int cpu_signal_handler(int host_signum, void *pinfo,
 566                        void *puc)
 567 {
 568     siginfo_t *info = pinfo;
 569     struct ucontext *uc = puc;
 570     unsigned long pc;
 571     uint16_t *pinsn;
 572     int is_write = 0;
 573
 574     pc = uc->uc_mcontext.psw.addr;
 575
 576     /* ??? On linux, the non-rt signal handler has 4 (!) arguments instead
 577        of the normal 2 arguments.  The 3rd argument contains the "int_code"
 578        from the hardware which does in fact contain the is_write value.
 579        The rt signal handler, as far as I can tell, does not give this value
 580        at all.  Not that we could get to it from here even if it were.  */
 581     /* ??? This is not even close to complete, since it ignores all
 582        of the read-modify-write instructions.  */
 583     pinsn = (uint16_t *)pc;
 584     switch (pinsn[0] >> 8) {
 585     case 0x50: /* ST */
 586     case 0x42: /* STC */
 587     case 0x40: /* STH */
 588         is_write = 1;
 589         break;
 590     case 0xc4: /* RIL format insns */
 591         switch (pinsn[0] & 0xf) {
 592         case 0xf: /* STRL */
 593         case 0xb: /* STGRL */
 594         case 0x7: /* STHRL */
 595             is_write = 1;
 596         }
 597         break;
 598     case 0xe3: /* RXY format insns */
 599         switch (pinsn[2] & 0xff) {
 600         case 0x50: /* STY */
 601         case 0x24: /* STG */
 602         case 0x72: /* STCY */
 603         case 0x70: /* STHY */
 604         case 0x8e: /* STPQ */
 605         case 0x3f: /* STRVH */
 606         case 0x3e: /* STRV */
 607         case 0x2f: /* STRVG */
 608             is_write = 1;
 609         }
 610         break;
 611     }
 612     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 613                              is_write, &uc->uc_sigmask, puc);
 614 }
 615
 616 #elif defined(__mips__)
 617
 618 int cpu_signal_handler(int host_signum, void *pinfo,
 619                        void *puc)
 620 {
 621     siginfo_t *info = pinfo;
 622     struct ucontext *uc = puc;
 623     greg_t pc = uc->uc_mcontext.pc;
 624     int is_write;
 625
 626     /* XXX: compute is_write */
 627     is_write = 0;
 628     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 629                              is_write, &uc->uc_sigmask, puc);
 630 }
 631
 632 #elif defined(__hppa__)
 633
 634 int cpu_signal_handler(int host_signum, void *pinfo,
 635                        void *puc)
 636 {
 637     siginfo_t *info = pinfo;
 638     struct ucontext *uc = puc;
 639     unsigned long pc = uc->uc_mcontext.sc_iaoq[0];
 640     uint32_t insn = *(uint32_t *)pc;
 641     int is_write = 0;
 642
 643     /* XXX: need kernel patch to get write flag faster.  */
 644     switch (insn >> 26) {
 645     case 0x1a: /* STW */
 646     case 0x19: /* STH */
 647     case 0x18: /* STB */
 648     case 0x1b: /* STWM */
 649         is_write = 1;
 650         break;
 651
 652     case 0x09: /* CSTWX, FSTWX, FSTWS */
 653     case 0x0b: /* CSTDX, FSTDX, FSTDS */
 654         /* Distinguish from coprocessor load ... */
 655         is_write = (insn >> 9) & 1;
 656         break;
 657
 658     case 0x03:
 659         switch ((insn >> 6) & 15) {
 660         case 0xa: /* STWS */
 661         case 0x9: /* STHS */
 662         case 0x8: /* STBS */
 663         case 0xe: /* STWAS */
 664         case 0xc: /* STBYS */
 665             is_write = 1;
 666         }
 667         break;
 668     }
 669
 670     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 671                              is_write, &uc->uc_sigmask, puc);
 672 }
 673
 674 #else
 675
 676 #error host CPU specific signal handler needed
 677
 678 #endif