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 "qemu/osdep.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 #ifdef __linux__
  37 #include <sys/ucontext.h>
  38 #endif
  39
  40 //#define DEBUG_SIGNAL
  41
  42 static void exception_action(CPUState *cpu)
  43 {
  44 #if defined(TARGET_I386)
  45     X86CPU *x86_cpu = X86_CPU(cpu);
  46     CPUX86State *env1 = &x86_cpu->env;
  47
  48     raise_exception_err(env1, cpu->exception_index, env1->error_code);
  49 #else
  50     cpu_loop_exit(cpu);
  51 #endif
  52 }
  53
  54 /* exit the current TB from a signal handler. The host registers are
  55    restored in a state compatible with the CPU emulator
  56  */
  57 void cpu_resume_from_signal(CPUState *cpu, void *puc)
  58 {
  59 #ifdef __linux__
  60     struct ucontext *uc = puc;
  61 #elif defined(__OpenBSD__)
  62     struct sigcontext *uc = puc;
  63 #endif
  64
  65     if (puc) {
  66         /* XXX: use siglongjmp ? */
  67 #ifdef __linux__
  68 #ifdef __ia64
  69         sigprocmask(SIG_SETMASK, (sigset_t *)&uc->uc_sigmask, NULL);
  70 #else
  71         sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
  72 #endif
  73 #elif defined(__OpenBSD__)
  74         sigprocmask(SIG_SETMASK, &uc->sc_mask, NULL);
  75 #endif
  76     }
  77     cpu->exception_index = -1;
  78     siglongjmp(cpu->jmp_env, 1);
  79 }
  80
  81 /* 'pc' is the host PC at which the exception was raised. 'address' is
  82    the effective address of the memory exception. 'is_write' is 1 if a
  83    write caused the exception and otherwise 0'. 'old_set' is the
  84    signal set which should be restored */
  85 static inline int handle_cpu_signal(uintptr_t pc, unsigned long address,
  86                                     int is_write, sigset_t *old_set,
  87                                     void *puc)
  88 {
  89     CPUState *cpu;
  90     CPUClass *cc;
  91     int ret;
  92
  93 #if defined(DEBUG_SIGNAL)
  94     printf("qemu: SIGSEGV pc=0x%08lx address=%08lx w=%d oldset=0x%08lx\n",
  95            pc, address, is_write, *(unsigned long *)old_set);
  96 #endif
  97     /* XXX: locking issue */
  98     if (is_write && h2g_valid(address)
  99         && page_unprotect(h2g(address), pc, puc)) {
 100         return 1;
 101     }
 102
 103     /* Convert forcefully to guest address space, invalid addresses
 104        are still valid segv ones */
 105     address = h2g_nocheck(address);
 106
 107     cpu = current_cpu;
 108     cc = CPU_GET_CLASS(cpu);
 109     /* see if it is an MMU fault */
 110     g_assert(cc->handle_mmu_fault);
 111     ret = cc->handle_mmu_fault(cpu, address, is_write, MMU_USER_IDX);
 112     if (ret < 0) {
 113         return 0; /* not an MMU fault */
 114     }
 115     if (ret == 0) {
 116         return 1; /* the MMU fault was handled without causing real CPU fault */
 117     }
 118     /* now we have a real cpu fault */
 119     cpu_restore_state(cpu, pc);
 120
 121     /* we restore the process signal mask as the sigreturn should
 122        do it (XXX: use sigsetjmp) */
 123     sigprocmask(SIG_SETMASK, old_set, NULL);
 124     exception_action(cpu);
 125
 126     /* never comes here */
 127     return 1;
 128 }
 129
 130 #if defined(__i386__)
 131
 132 #if defined(__APPLE__)
 133 #include <sys/ucontext.h>
 134
 135 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext->ss.eip))
 136 #define TRAP_sig(context)    ((context)->uc_mcontext->es.trapno)
 137 #define ERROR_sig(context)   ((context)->uc_mcontext->es.err)
 138 #define MASK_sig(context)    ((context)->uc_sigmask)
 139 #elif defined(__NetBSD__)
 140 #include <ucontext.h>
 141
 142 #define EIP_sig(context)     ((context)->uc_mcontext.__gregs[_REG_EIP])
 143 #define TRAP_sig(context)    ((context)->uc_mcontext.__gregs[_REG_TRAPNO])
 144 #define ERROR_sig(context)   ((context)->uc_mcontext.__gregs[_REG_ERR])
 145 #define MASK_sig(context)    ((context)->uc_sigmask)
 146 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 147 #include <ucontext.h>
 148
 149 #define EIP_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_eip))
 150 #define TRAP_sig(context)    ((context)->uc_mcontext.mc_trapno)
 151 #define ERROR_sig(context)   ((context)->uc_mcontext.mc_err)
 152 #define MASK_sig(context)    ((context)->uc_sigmask)
 153 #elif defined(__OpenBSD__)
 154 #define EIP_sig(context)     ((context)->sc_eip)
 155 #define TRAP_sig(context)    ((context)->sc_trapno)
 156 #define ERROR_sig(context)   ((context)->sc_err)
 157 #define MASK_sig(context)    ((context)->sc_mask)
 158 #else
 159 #define EIP_sig(context)     ((context)->uc_mcontext.gregs[REG_EIP])
 160 #define TRAP_sig(context)    ((context)->uc_mcontext.gregs[REG_TRAPNO])
 161 #define ERROR_sig(context)   ((context)->uc_mcontext.gregs[REG_ERR])
 162 #define MASK_sig(context)    ((context)->uc_sigmask)
 163 #endif
 164
 165 int cpu_signal_handler(int host_signum, void *pinfo,
 166                        void *puc)
 167 {
 168     siginfo_t *info = pinfo;
 169 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
 170     ucontext_t *uc = puc;
 171 #elif defined(__OpenBSD__)
 172     struct sigcontext *uc = puc;
 173 #else
 174     struct ucontext *uc = puc;
 175 #endif
 176     unsigned long pc;
 177     int trapno;
 178
 179 #ifndef REG_EIP
 180 /* for glibc 2.1 */
 181 #define REG_EIP    EIP
 182 #define REG_ERR    ERR
 183 #define REG_TRAPNO TRAPNO
 184 #endif
 185     pc = EIP_sig(uc);
 186     trapno = TRAP_sig(uc);
 187     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 188                              trapno == 0xe ?
 189                              (ERROR_sig(uc) >> 1) & 1 : 0,
 190                              &MASK_sig(uc), puc);
 191 }
 192
 193 #elif defined(__x86_64__)
 194
 195 #ifdef __NetBSD__
 196 #define PC_sig(context)       _UC_MACHINE_PC(context)
 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(__OpenBSD__)
 201 #define PC_sig(context)       ((context)->sc_rip)
 202 #define TRAP_sig(context)     ((context)->sc_trapno)
 203 #define ERROR_sig(context)    ((context)->sc_err)
 204 #define MASK_sig(context)     ((context)->sc_mask)
 205 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 206 #include <ucontext.h>
 207
 208 #define PC_sig(context)  (*((unsigned long *)&(context)->uc_mcontext.mc_rip))
 209 #define TRAP_sig(context)     ((context)->uc_mcontext.mc_trapno)
 210 #define ERROR_sig(context)    ((context)->uc_mcontext.mc_err)
 211 #define MASK_sig(context)     ((context)->uc_sigmask)
 212 #else
 213 #define PC_sig(context)       ((context)->uc_mcontext.gregs[REG_RIP])
 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     unsigned long pc;
 224 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
 225     ucontext_t *uc = puc;
 226 #elif defined(__OpenBSD__)
 227     struct sigcontext *uc = puc;
 228 #else
 229     struct ucontext *uc = puc;
 230 #endif
 231
 232     pc = PC_sig(uc);
 233     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 234                              TRAP_sig(uc) == 0xe ?
 235                              (ERROR_sig(uc) >> 1) & 1 : 0,
 236                              &MASK_sig(uc), puc);
 237 }
 238
 239 #elif defined(_ARCH_PPC)
 240
 241 /***********************************************************************
 242  * signal context platform-specific definitions
 243  * From Wine
 244  */
 245 #ifdef linux
 246 /* All Registers access - only for local access */
 247 #define REG_sig(reg_name, context)              \
 248     ((context)->uc_mcontext.regs->reg_name)
 249 /* Gpr Registers access  */
 250 #define GPR_sig(reg_num, context)              REG_sig(gpr[reg_num], context)
 251 /* Program counter */
 252 #define IAR_sig(context)                       REG_sig(nip, context)
 253 /* Machine State Register (Supervisor) */
 254 #define MSR_sig(context)                       REG_sig(msr, context)
 255 /* Count register */
 256 #define CTR_sig(context)                       REG_sig(ctr, context)
 257 /* User's integer exception register */
 258 #define XER_sig(context)                       REG_sig(xer, context)
 259 /* Link register */
 260 #define LR_sig(context)                        REG_sig(link, context)
 261 /* Condition register */
 262 #define CR_sig(context)                        REG_sig(ccr, context)
 263
 264 /* Float Registers access  */
 265 #define FLOAT_sig(reg_num, context)                                     \
 266     (((double *)((char *)((context)->uc_mcontext.regs + 48 * 4)))[reg_num])
 267 #define FPSCR_sig(context) \
 268     (*(int *)((char *)((context)->uc_mcontext.regs + (48 + 32 * 2) * 4)))
 269 /* Exception Registers access */
 270 #define DAR_sig(context)                       REG_sig(dar, context)
 271 #define DSISR_sig(context)                     REG_sig(dsisr, context)
 272 #define TRAP_sig(context)                      REG_sig(trap, context)
 273 #endif /* linux */
 274
 275 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 276 #include <ucontext.h>
 277 #define IAR_sig(context)               ((context)->uc_mcontext.mc_srr0)
 278 #define MSR_sig(context)               ((context)->uc_mcontext.mc_srr1)
 279 #define CTR_sig(context)               ((context)->uc_mcontext.mc_ctr)
 280 #define XER_sig(context)               ((context)->uc_mcontext.mc_xer)
 281 #define LR_sig(context)                ((context)->uc_mcontext.mc_lr)
 282 #define CR_sig(context)                ((context)->uc_mcontext.mc_cr)
 283 /* Exception Registers access */
 284 #define DAR_sig(context)               ((context)->uc_mcontext.mc_dar)
 285 #define DSISR_sig(context)             ((context)->uc_mcontext.mc_dsisr)
 286 #define TRAP_sig(context)              ((context)->uc_mcontext.mc_exc)
 287 #endif /* __FreeBSD__|| __FreeBSD_kernel__ */
 288
 289 #ifdef __APPLE__
 290 #include <sys/ucontext.h>
 291 typedef struct ucontext SIGCONTEXT;
 292 /* All Registers access - only for local access */
 293 #define REG_sig(reg_name, context)              \
 294     ((context)->uc_mcontext->ss.reg_name)
 295 #define FLOATREG_sig(reg_name, context)         \
 296     ((context)->uc_mcontext->fs.reg_name)
 297 #define EXCEPREG_sig(reg_name, context)         \
 298     ((context)->uc_mcontext->es.reg_name)
 299 #define VECREG_sig(reg_name, context)           \
 300     ((context)->uc_mcontext->vs.reg_name)
 301 /* Gpr Registers access */
 302 #define GPR_sig(reg_num, context)              REG_sig(r##reg_num, context)
 303 /* Program counter */
 304 #define IAR_sig(context)                       REG_sig(srr0, context)
 305 /* Machine State Register (Supervisor) */
 306 #define MSR_sig(context)                       REG_sig(srr1, context)
 307 #define CTR_sig(context)                       REG_sig(ctr, context)
 308 /* Link register */
 309 #define XER_sig(context)                       REG_sig(xer, context)
 310 /* User's integer exception register */
 311 #define LR_sig(context)                        REG_sig(lr, context)
 312 /* Condition register */
 313 #define CR_sig(context)                        REG_sig(cr, context)
 314 /* Float Registers access */
 315 #define FLOAT_sig(reg_num, context)             \
 316     FLOATREG_sig(fpregs[reg_num], context)
 317 #define FPSCR_sig(context)                      \
 318     ((double)FLOATREG_sig(fpscr, context))
 319 /* Exception Registers access */
 320 /* Fault registers for coredump */
 321 #define DAR_sig(context)                       EXCEPREG_sig(dar, context)
 322 #define DSISR_sig(context)                     EXCEPREG_sig(dsisr, context)
 323 /* number of powerpc exception taken */
 324 #define TRAP_sig(context)                      EXCEPREG_sig(exception, context)
 325 #endif /* __APPLE__ */
 326
 327 int cpu_signal_handler(int host_signum, void *pinfo,
 328                        void *puc)
 329 {
 330     siginfo_t *info = pinfo;
 331 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 332     ucontext_t *uc = puc;
 333 #else
 334     struct ucontext *uc = puc;
 335 #endif
 336     unsigned long pc;
 337     int is_write;
 338
 339     pc = IAR_sig(uc);
 340     is_write = 0;
 341 #if 0
 342     /* ppc 4xx case */
 343     if (DSISR_sig(uc) & 0x00800000) {
 344         is_write = 1;
 345     }
 346 #else
 347     if (TRAP_sig(uc) != 0x400 && (DSISR_sig(uc) & 0x02000000)) {
 348         is_write = 1;
 349     }
 350 #endif
 351     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 352                              is_write, &uc->uc_sigmask, puc);
 353 }
 354
 355 #elif defined(__alpha__)
 356
 357 int cpu_signal_handler(int host_signum, void *pinfo,
 358                            void *puc)
 359 {
 360     siginfo_t *info = pinfo;
 361     struct ucontext *uc = puc;
 362     uint32_t *pc = uc->uc_mcontext.sc_pc;
 363     uint32_t insn = *pc;
 364     int is_write = 0;
 365
 366     /* XXX: need kernel patch to get write flag faster */
 367     switch (insn >> 26) {
 368     case 0x0d: /* stw */
 369     case 0x0e: /* stb */
 370     case 0x0f: /* stq_u */
 371     case 0x24: /* stf */
 372     case 0x25: /* stg */
 373     case 0x26: /* sts */
 374     case 0x27: /* stt */
 375     case 0x2c: /* stl */
 376     case 0x2d: /* stq */
 377     case 0x2e: /* stl_c */
 378     case 0x2f: /* stq_c */
 379         is_write = 1;
 380     }
 381
 382     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 383                              is_write, &uc->uc_sigmask, puc);
 384 }
 385 #elif defined(__sparc__)
 386
 387 int cpu_signal_handler(int host_signum, void *pinfo,
 388                        void *puc)
 389 {
 390     siginfo_t *info = pinfo;
 391     int is_write;
 392     uint32_t insn;
 393 #if !defined(__arch64__) || defined(CONFIG_SOLARIS)
 394     uint32_t *regs = (uint32_t *)(info + 1);
 395     void *sigmask = (regs + 20);
 396     /* XXX: is there a standard glibc define ? */
 397     unsigned long pc = regs[1];
 398 #else
 399 #ifdef __linux__
 400     struct sigcontext *sc = puc;
 401     unsigned long pc = sc->sigc_regs.tpc;
 402     void *sigmask = (void *)sc->sigc_mask;
 403 #elif defined(__OpenBSD__)
 404     struct sigcontext *uc = puc;
 405     unsigned long pc = uc->sc_pc;
 406     void *sigmask = (void *)(long)uc->sc_mask;
 407 #elif defined(__NetBSD__)
 408     ucontext_t *uc = puc;
 409     unsigned long pc = _UC_MACHINE_PC(uc);
 410     void *sigmask = (void *)&uc->uc_sigmask;
 411 #endif
 412 #endif
 413
 414     /* XXX: need kernel patch to get write flag faster */
 415     is_write = 0;
 416     insn = *(uint32_t *)pc;
 417     if ((insn >> 30) == 3) {
 418         switch ((insn >> 19) & 0x3f) {
 419         case 0x05: /* stb */
 420         case 0x15: /* stba */
 421         case 0x06: /* sth */
 422         case 0x16: /* stha */
 423         case 0x04: /* st */
 424         case 0x14: /* sta */
 425         case 0x07: /* std */
 426         case 0x17: /* stda */
 427         case 0x0e: /* stx */
 428         case 0x1e: /* stxa */
 429         case 0x24: /* stf */
 430         case 0x34: /* stfa */
 431         case 0x27: /* stdf */
 432         case 0x37: /* stdfa */
 433         case 0x26: /* stqf */
 434         case 0x36: /* stqfa */
 435         case 0x25: /* stfsr */
 436         case 0x3c: /* casa */
 437         case 0x3e: /* casxa */
 438             is_write = 1;
 439             break;
 440         }
 441     }
 442     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 443                              is_write, sigmask, NULL);
 444 }
 445
 446 #elif defined(__arm__)
 447
 448 #if defined(__NetBSD__)
 449 #include <ucontext.h>
 450 #endif
 451
 452 int cpu_signal_handler(int host_signum, void *pinfo,
 453                        void *puc)
 454 {
 455     siginfo_t *info = pinfo;
 456 #if defined(__NetBSD__)
 457     ucontext_t *uc = puc;
 458 #else
 459     struct ucontext *uc = puc;
 460 #endif
 461     unsigned long pc;
 462     int is_write;
 463
 464 #if defined(__NetBSD__)
 465     pc = uc->uc_mcontext.__gregs[_REG_R15];
 466 #elif defined(__GLIBC__) && (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
 467     pc = uc->uc_mcontext.gregs[R15];
 468 #else
 469     pc = uc->uc_mcontext.arm_pc;
 470 #endif
 471
 472     /* error_code is the FSR value, in which bit 11 is WnR (assuming a v6 or
 473      * later processor; on v5 we will always report this as a read).
 474      */
 475     is_write = extract32(uc->uc_mcontext.error_code, 11, 1);
 476     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 477                              is_write,
 478                              &uc->uc_sigmask, puc);
 479 }
 480
 481 #elif defined(__aarch64__)
 482
 483 int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
 484 {
 485     siginfo_t *info = pinfo;
 486     struct ucontext *uc = puc;
 487     uintptr_t pc = uc->uc_mcontext.pc;
 488     uint32_t insn = *(uint32_t *)pc;
 489     bool is_write;
 490
 491     /* XXX: need kernel patch to get write flag faster.  */
 492     is_write = (   (insn & 0xbfff0000) == 0x0c000000   /* C3.3.1 */
 493                 || (insn & 0xbfe00000) == 0x0c800000   /* C3.3.2 */
 494                 || (insn & 0xbfdf0000) == 0x0d000000   /* C3.3.3 */
 495                 || (insn & 0xbfc00000) == 0x0d800000   /* C3.3.4 */
 496                 || (insn & 0x3f400000) == 0x08000000   /* C3.3.6 */
 497                 || (insn & 0x3bc00000) == 0x39000000   /* C3.3.13 */
 498                 || (insn & 0x3fc00000) == 0x3d800000   /* ... 128bit */
 499                 /* Ingore bits 10, 11 & 21, controlling indexing.  */
 500                 || (insn & 0x3bc00000) == 0x38000000   /* C3.3.8-12 */
 501                 || (insn & 0x3fe00000) == 0x3c800000   /* ... 128bit */
 502                 /* Ignore bits 23 & 24, controlling indexing.  */
 503                 || (insn & 0x3a400000) == 0x28000000); /* C3.3.7,14-16 */
 504
 505     return handle_cpu_signal(pc, (uintptr_t)info->si_addr,
 506                              is_write, &uc->uc_sigmask, puc);
 507 }
 508
 509 #elif defined(__mc68000)
 510
 511 int cpu_signal_handler(int host_signum, void *pinfo,
 512                        void *puc)
 513 {
 514     siginfo_t *info = pinfo;
 515     struct ucontext *uc = puc;
 516     unsigned long pc;
 517     int is_write;
 518
 519     pc = uc->uc_mcontext.gregs[16];
 520     /* XXX: compute is_write */
 521     is_write = 0;
 522     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 523                              is_write,
 524                              &uc->uc_sigmask, puc);
 525 }
 526
 527 #elif defined(__ia64)
 528
 529 #ifndef __ISR_VALID
 530   /* This ought to be in <bits/siginfo.h>... */
 531 # define __ISR_VALID    1
 532 #endif
 533
 534 int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
 535 {
 536     siginfo_t *info = pinfo;
 537     struct ucontext *uc = puc;
 538     unsigned long ip;
 539     int is_write = 0;
 540
 541     ip = uc->uc_mcontext.sc_ip;
 542     switch (host_signum) {
 543     case SIGILL:
 544     case SIGFPE:
 545     case SIGSEGV:
 546     case SIGBUS:
 547     case SIGTRAP:
 548         if (info->si_code && (info->si_segvflags & __ISR_VALID)) {
 549             /* ISR.W (write-access) is bit 33:  */
 550             is_write = (info->si_isr >> 33) & 1;
 551         }
 552         break;
 553
 554     default:
 555         break;
 556     }
 557     return handle_cpu_signal(ip, (unsigned long)info->si_addr,
 558                              is_write,
 559                              (sigset_t *)&uc->uc_sigmask, puc);
 560 }
 561
 562 #elif defined(__s390__)
 563
 564 int cpu_signal_handler(int host_signum, void *pinfo,
 565                        void *puc)
 566 {
 567     siginfo_t *info = pinfo;
 568     struct ucontext *uc = puc;
 569     unsigned long pc;
 570     uint16_t *pinsn;
 571     int is_write = 0;
 572
 573     pc = uc->uc_mcontext.psw.addr;
 574
 575     /* ??? On linux, the non-rt signal handler has 4 (!) arguments instead
 576        of the normal 2 arguments.  The 3rd argument contains the "int_code"
 577        from the hardware which does in fact contain the is_write value.
 578        The rt signal handler, as far as I can tell, does not give this value
 579        at all.  Not that we could get to it from here even if it were.  */
 580     /* ??? This is not even close to complete, since it ignores all
 581        of the read-modify-write instructions.  */
 582     pinsn = (uint16_t *)pc;
 583     switch (pinsn[0] >> 8) {
 584     case 0x50: /* ST */
 585     case 0x42: /* STC */
 586     case 0x40: /* STH */
 587         is_write = 1;
 588         break;
 589     case 0xc4: /* RIL format insns */
 590         switch (pinsn[0] & 0xf) {
 591         case 0xf: /* STRL */
 592         case 0xb: /* STGRL */
 593         case 0x7: /* STHRL */
 594             is_write = 1;
 595         }
 596         break;
 597     case 0xe3: /* RXY format insns */
 598         switch (pinsn[2] & 0xff) {
 599         case 0x50: /* STY */
 600         case 0x24: /* STG */
 601         case 0x72: /* STCY */
 602         case 0x70: /* STHY */
 603         case 0x8e: /* STPQ */
 604         case 0x3f: /* STRVH */
 605         case 0x3e: /* STRV */
 606         case 0x2f: /* STRVG */
 607             is_write = 1;
 608         }
 609         break;
 610     }
 611     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 612                              is_write, &uc->uc_sigmask, puc);
 613 }
 614
 615 #elif defined(__mips__)
 616
 617 int cpu_signal_handler(int host_signum, void *pinfo,
 618                        void *puc)
 619 {
 620     siginfo_t *info = pinfo;
 621     struct ucontext *uc = puc;
 622     greg_t pc = uc->uc_mcontext.pc;
 623     int is_write;
 624
 625     /* XXX: compute is_write */
 626     is_write = 0;
 627     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 628                              is_write, &uc->uc_sigmask, puc);
 629 }
 630
 631 #elif defined(__hppa__)
 632
 633 int cpu_signal_handler(int host_signum, void *pinfo,
 634                        void *puc)
 635 {
 636     siginfo_t *info = pinfo;
 637     struct ucontext *uc = puc;
 638     unsigned long pc = uc->uc_mcontext.sc_iaoq[0];
 639     uint32_t insn = *(uint32_t *)pc;
 640     int is_write = 0;
 641
 642     /* XXX: need kernel patch to get write flag faster.  */
 643     switch (insn >> 26) {
 644     case 0x1a: /* STW */
 645     case 0x19: /* STH */
 646     case 0x18: /* STB */
 647     case 0x1b: /* STWM */
 648         is_write = 1;
 649         break;
 650
 651     case 0x09: /* CSTWX, FSTWX, FSTWS */
 652     case 0x0b: /* CSTDX, FSTDX, FSTDS */
 653         /* Distinguish from coprocessor load ... */
 654         is_write = (insn >> 9) & 1;
 655         break;
 656
 657     case 0x03:
 658         switch ((insn >> 6) & 15) {
 659         case 0xa: /* STWS */
 660         case 0x9: /* STHS */
 661         case 0x8: /* STBS */
 662         case 0xe: /* STWAS */
 663         case 0xc: /* STBYS */
 664             is_write = 1;
 665         }
 666         break;
 667     }
 668
 669     return handle_cpu_signal(pc, (unsigned long)info->si_addr,
 670                              is_write, &uc->uc_sigmask, puc);
 671 }
 672
 673 #else
 674
 675 #error host CPU specific signal handler needed
 676
 677 #endif