linux-user/i386/signal.c

   1 /*
   2  *  Emulation of Linux signals
   3  *
   4  *  Copyright (c) 2003 Fabrice Bellard
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program 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
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #include "qemu/osdep.h"
  20 #include "qemu.h"
  21 #include "signal-common.h"
  22 #include "linux-user/trace.h"
  23
  24 /* from the Linux kernel - /arch/x86/include/uapi/asm/sigcontext.h */
  25
  26 struct target_fpreg {
  27     uint16_t significand[4];
  28     uint16_t exponent;
  29 };
  30
  31 struct target_fpxreg {
  32     uint16_t significand[4];
  33     uint16_t exponent;
  34     uint16_t padding[3];
  35 };
  36
  37 struct target_xmmreg {
  38     uint32_t element[4];
  39 };
  40
  41 struct target_fpstate_32 {
  42     /* Regular FPU environment */
  43     uint32_t cw;
  44     uint32_t sw;
  45     uint32_t tag;
  46     uint32_t ipoff;
  47     uint32_t cssel;
  48     uint32_t dataoff;
  49     uint32_t datasel;
  50     struct target_fpreg st[8];
  51     uint16_t  status;
  52     uint16_t  magic;          /* 0xffff = regular FPU data only */
  53
  54     /* FXSR FPU environment */
  55     uint32_t _fxsr_env[6];   /* FXSR FPU env is ignored */
  56     uint32_t mxcsr;
  57     uint32_t reserved;
  58     struct target_fpxreg fxsr_st[8]; /* FXSR FPU reg data is ignored */
  59     struct target_xmmreg xmm[8];
  60     uint32_t padding[56];
  61 };
  62
  63 struct target_fpstate_64 {
  64     /* FXSAVE format */
  65     uint16_t cw;
  66     uint16_t sw;
  67     uint16_t twd;
  68     uint16_t fop;
  69     uint64_t rip;
  70     uint64_t rdp;
  71     uint32_t mxcsr;
  72     uint32_t mxcsr_mask;
  73     uint32_t st_space[32];
  74     uint32_t xmm_space[64];
  75     uint32_t reserved[24];
  76 };
  77
  78 #ifndef TARGET_X86_64
  79 # define target_fpstate target_fpstate_32
  80 #else
  81 # define target_fpstate target_fpstate_64
  82 #endif
  83
  84 struct target_sigcontext_32 {
  85     uint16_t gs, __gsh;
  86     uint16_t fs, __fsh;
  87     uint16_t es, __esh;
  88     uint16_t ds, __dsh;
  89     uint32_t edi;
  90     uint32_t esi;
  91     uint32_t ebp;
  92     uint32_t esp;
  93     uint32_t ebx;
  94     uint32_t edx;
  95     uint32_t ecx;
  96     uint32_t eax;
  97     uint32_t trapno;
  98     uint32_t err;
  99     uint32_t eip;
 100     uint16_t cs, __csh;
 101     uint32_t eflags;
 102     uint32_t esp_at_signal;
 103     uint16_t ss, __ssh;
 104     uint32_t fpstate; /* pointer */
 105     uint32_t oldmask;
 106     uint32_t cr2;
 107 };
 108
 109 struct target_sigcontext_64 {
 110     uint64_t r8;
 111     uint64_t r9;
 112     uint64_t r10;
 113     uint64_t r11;
 114     uint64_t r12;
 115     uint64_t r13;
 116     uint64_t r14;
 117     uint64_t r15;
 118
 119     uint64_t rdi;
 120     uint64_t rsi;
 121     uint64_t rbp;
 122     uint64_t rbx;
 123     uint64_t rdx;
 124     uint64_t rax;
 125     uint64_t rcx;
 126     uint64_t rsp;
 127     uint64_t rip;
 128
 129     uint64_t eflags;
 130
 131     uint16_t cs;
 132     uint16_t gs;
 133     uint16_t fs;
 134     uint16_t ss;
 135
 136     uint64_t err;
 137     uint64_t trapno;
 138     uint64_t oldmask;
 139     uint64_t cr2;
 140
 141     uint64_t fpstate; /* pointer */
 142     uint64_t padding[8];
 143 };
 144
 145 #ifndef TARGET_X86_64
 146 # define target_sigcontext target_sigcontext_32
 147 #else
 148 # define target_sigcontext target_sigcontext_64
 149 #endif
 150
 151 /* see Linux/include/uapi/asm-generic/ucontext.h */
 152 struct target_ucontext {
 153     abi_ulong         tuc_flags;
 154     abi_ulong         tuc_link;
 155     target_stack_t    tuc_stack;
 156     struct target_sigcontext tuc_mcontext;
 157     target_sigset_t   tuc_sigmask;  /* mask last for extensibility */
 158 };
 159
 160 #ifndef TARGET_X86_64
 161 struct sigframe {
 162     abi_ulong pretcode;
 163     int sig;
 164     struct target_sigcontext sc;
 165     struct target_fpstate fpstate;
 166     abi_ulong extramask[TARGET_NSIG_WORDS-1];
 167     char retcode[8];
 168 };
 169
 170 struct rt_sigframe {
 171     abi_ulong pretcode;
 172     int sig;
 173     abi_ulong pinfo;
 174     abi_ulong puc;
 175     struct target_siginfo info;
 176     struct target_ucontext uc;
 177     struct target_fpstate fpstate;
 178     char retcode[8];
 179 };
 180
 181 #else
 182
 183 struct rt_sigframe {
 184     abi_ulong pretcode;
 185     struct target_ucontext uc;
 186     struct target_siginfo info;
 187     struct target_fpstate fpstate;
 188 };
 189
 190 #endif
 191
 192 /*
 193  * Set up a signal frame.
 194  */
 195
 196 /* XXX: save x87 state */
 197 static void setup_sigcontext(struct target_sigcontext *sc,
 198         struct target_fpstate *fpstate, CPUX86State *env, abi_ulong mask,
 199         abi_ulong fpstate_addr)
 200 {
 201     CPUState *cs = env_cpu(env);
 202 #ifndef TARGET_X86_64
 203     uint16_t magic;
 204
 205     /* already locked in setup_frame() */
 206     __put_user(env->segs[R_GS].selector, (unsigned int *)&sc->gs);
 207     __put_user(env->segs[R_FS].selector, (unsigned int *)&sc->fs);
 208     __put_user(env->segs[R_ES].selector, (unsigned int *)&sc->es);
 209     __put_user(env->segs[R_DS].selector, (unsigned int *)&sc->ds);
 210     __put_user(env->regs[R_EDI], &sc->edi);
 211     __put_user(env->regs[R_ESI], &sc->esi);
 212     __put_user(env->regs[R_EBP], &sc->ebp);
 213     __put_user(env->regs[R_ESP], &sc->esp);
 214     __put_user(env->regs[R_EBX], &sc->ebx);
 215     __put_user(env->regs[R_EDX], &sc->edx);
 216     __put_user(env->regs[R_ECX], &sc->ecx);
 217     __put_user(env->regs[R_EAX], &sc->eax);
 218     __put_user(cs->exception_index, &sc->trapno);
 219     __put_user(env->error_code, &sc->err);
 220     __put_user(env->eip, &sc->eip);
 221     __put_user(env->segs[R_CS].selector, (unsigned int *)&sc->cs);
 222     __put_user(env->eflags, &sc->eflags);
 223     __put_user(env->regs[R_ESP], &sc->esp_at_signal);
 224     __put_user(env->segs[R_SS].selector, (unsigned int *)&sc->ss);
 225
 226     cpu_x86_fsave(env, fpstate_addr, 1);
 227     fpstate->status = fpstate->sw;
 228     magic = 0xffff;
 229     __put_user(magic, &fpstate->magic);
 230     __put_user(fpstate_addr, &sc->fpstate);
 231
 232     /* non-iBCS2 extensions.. */
 233     __put_user(mask, &sc->oldmask);
 234     __put_user(env->cr[2], &sc->cr2);
 235 #else
 236     __put_user(env->regs[R_EDI], &sc->rdi);
 237     __put_user(env->regs[R_ESI], &sc->rsi);
 238     __put_user(env->regs[R_EBP], &sc->rbp);
 239     __put_user(env->regs[R_ESP], &sc->rsp);
 240     __put_user(env->regs[R_EBX], &sc->rbx);
 241     __put_user(env->regs[R_EDX], &sc->rdx);
 242     __put_user(env->regs[R_ECX], &sc->rcx);
 243     __put_user(env->regs[R_EAX], &sc->rax);
 244
 245     __put_user(env->regs[8], &sc->r8);
 246     __put_user(env->regs[9], &sc->r9);
 247     __put_user(env->regs[10], &sc->r10);
 248     __put_user(env->regs[11], &sc->r11);
 249     __put_user(env->regs[12], &sc->r12);
 250     __put_user(env->regs[13], &sc->r13);
 251     __put_user(env->regs[14], &sc->r14);
 252     __put_user(env->regs[15], &sc->r15);
 253
 254     __put_user(cs->exception_index, &sc->trapno);
 255     __put_user(env->error_code, &sc->err);
 256     __put_user(env->eip, &sc->rip);
 257
 258     __put_user(env->eflags, &sc->eflags);
 259     __put_user(env->segs[R_CS].selector, &sc->cs);
 260     __put_user((uint16_t)0, &sc->gs);
 261     __put_user((uint16_t)0, &sc->fs);
 262     __put_user(env->segs[R_SS].selector, &sc->ss);
 263
 264     __put_user(mask, &sc->oldmask);
 265     __put_user(env->cr[2], &sc->cr2);
 266
 267     /* fpstate_addr must be 16 byte aligned for fxsave */
 268     assert(!(fpstate_addr & 0xf));
 269
 270     cpu_x86_fxsave(env, fpstate_addr);
 271     __put_user(fpstate_addr, &sc->fpstate);
 272 #endif
 273 }
 274
 275 /*
 276  * Determine which stack to use..
 277  */
 278
 279 static inline abi_ulong
 280 get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size)
 281 {
 282     unsigned long esp;
 283
 284     /* Default to using normal stack */
 285     esp = get_sp_from_cpustate(env);
 286 #ifdef TARGET_X86_64
 287     esp -= 128; /* this is the redzone */
 288 #endif
 289
 290     /* This is the X/Open sanctioned signal stack switching.  */
 291     if (ka->sa_flags & TARGET_SA_ONSTACK) {
 292         esp = target_sigsp(esp, ka);
 293     } else {
 294 #ifndef TARGET_X86_64
 295         /* This is the legacy signal stack switching. */
 296         if ((env->segs[R_SS].selector & 0xffff) != __USER_DS &&
 297                 !(ka->sa_flags & TARGET_SA_RESTORER) &&
 298                 ka->sa_restorer) {
 299             esp = (unsigned long) ka->sa_restorer;
 300         }
 301 #endif
 302     }
 303
 304 #ifndef TARGET_X86_64
 305     return (esp - frame_size) & -8ul;
 306 #else
 307     return ((esp - frame_size) & (~15ul)) - 8;
 308 #endif
 309 }
 310
 311 #ifndef TARGET_X86_64
 312 /* compare linux/arch/i386/kernel/signal.c:setup_frame() */
 313 void setup_frame(int sig, struct target_sigaction *ka,
 314                  target_sigset_t *set, CPUX86State *env)
 315 {
 316     abi_ulong frame_addr;
 317     struct sigframe *frame;
 318     int i;
 319
 320     frame_addr = get_sigframe(ka, env, sizeof(*frame));
 321     trace_user_setup_frame(env, frame_addr);
 322
 323     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
 324         goto give_sigsegv;
 325
 326     __put_user(sig, &frame->sig);
 327
 328     setup_sigcontext(&frame->sc, &frame->fpstate, env, set->sig[0],
 329             frame_addr + offsetof(struct sigframe, fpstate));
 330
 331     for(i = 1; i < TARGET_NSIG_WORDS; i++) {
 332         __put_user(set->sig[i], &frame->extramask[i - 1]);
 333     }
 334
 335     /* Set up to return from userspace.  If provided, use a stub
 336        already in userspace.  */
 337     if (ka->sa_flags & TARGET_SA_RESTORER) {
 338         __put_user(ka->sa_restorer, &frame->pretcode);
 339     } else {
 340         uint16_t val16;
 341         abi_ulong retcode_addr;
 342         retcode_addr = frame_addr + offsetof(struct sigframe, retcode);
 343         __put_user(retcode_addr, &frame->pretcode);
 344         /* This is popl %eax ; movl $,%eax ; int $0x80 */
 345         val16 = 0xb858;
 346         __put_user(val16, (uint16_t *)(frame->retcode+0));
 347         __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2));
 348         val16 = 0x80cd;
 349         __put_user(val16, (uint16_t *)(frame->retcode+6));
 350     }
 351
 352     /* Set up registers for signal handler */
 353     env->regs[R_ESP] = frame_addr;
 354     env->eip = ka->_sa_handler;
 355
 356     cpu_x86_load_seg(env, R_DS, __USER_DS);
 357     cpu_x86_load_seg(env, R_ES, __USER_DS);
 358     cpu_x86_load_seg(env, R_SS, __USER_DS);
 359     cpu_x86_load_seg(env, R_CS, __USER_CS);
 360     env->eflags &= ~TF_MASK;
 361
 362     unlock_user_struct(frame, frame_addr, 1);
 363
 364     return;
 365
 366 give_sigsegv:
 367     force_sigsegv(sig);
 368 }
 369 #endif
 370
 371 /* compare linux/arch/x86/kernel/signal.c:setup_rt_frame() */
 372 void setup_rt_frame(int sig, struct target_sigaction *ka,
 373                     target_siginfo_t *info,
 374                     target_sigset_t *set, CPUX86State *env)
 375 {
 376     abi_ulong frame_addr;
 377 #ifndef TARGET_X86_64
 378     abi_ulong addr;
 379 #endif
 380     struct rt_sigframe *frame;
 381     int i;
 382
 383     frame_addr = get_sigframe(ka, env, sizeof(*frame));
 384     trace_user_setup_rt_frame(env, frame_addr);
 385
 386     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
 387         goto give_sigsegv;
 388
 389     /* These fields are only in rt_sigframe on 32 bit */
 390 #ifndef TARGET_X86_64
 391     __put_user(sig, &frame->sig);
 392     addr = frame_addr + offsetof(struct rt_sigframe, info);
 393     __put_user(addr, &frame->pinfo);
 394     addr = frame_addr + offsetof(struct rt_sigframe, uc);
 395     __put_user(addr, &frame->puc);
 396 #endif
 397     if (ka->sa_flags & TARGET_SA_SIGINFO) {
 398         tswap_siginfo(&frame->info, info);
 399     }
 400
 401     /* Create the ucontext.  */
 402     __put_user(0, &frame->uc.tuc_flags);
 403     __put_user(0, &frame->uc.tuc_link);
 404     target_save_altstack(&frame->uc.tuc_stack, env);
 405     setup_sigcontext(&frame->uc.tuc_mcontext, &frame->fpstate, env,
 406             set->sig[0], frame_addr + offsetof(struct rt_sigframe, fpstate));
 407
 408     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
 409         __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
 410     }
 411
 412     /* Set up to return from userspace.  If provided, use a stub
 413        already in userspace.  */
 414 #ifndef TARGET_X86_64
 415     if (ka->sa_flags & TARGET_SA_RESTORER) {
 416         __put_user(ka->sa_restorer, &frame->pretcode);
 417     } else {
 418         uint16_t val16;
 419         addr = frame_addr + offsetof(struct rt_sigframe, retcode);
 420         __put_user(addr, &frame->pretcode);
 421         /* This is movl $,%eax ; int $0x80 */
 422         __put_user(0xb8, (char *)(frame->retcode+0));
 423         __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));
 424         val16 = 0x80cd;
 425         __put_user(val16, (uint16_t *)(frame->retcode+5));
 426     }
 427 #else
 428     /* XXX: Would be slightly better to return -EFAULT here if test fails
 429        assert(ka->sa_flags & TARGET_SA_RESTORER); */
 430     __put_user(ka->sa_restorer, &frame->pretcode);
 431 #endif
 432
 433     /* Set up registers for signal handler */
 434     env->regs[R_ESP] = frame_addr;
 435     env->eip = ka->_sa_handler;
 436
 437 #ifndef TARGET_X86_64
 438     env->regs[R_EAX] = sig;
 439     env->regs[R_EDX] = (unsigned long)&frame->info;
 440     env->regs[R_ECX] = (unsigned long)&frame->uc;
 441 #else
 442     env->regs[R_EAX] = 0;
 443     env->regs[R_EDI] = sig;
 444     env->regs[R_ESI] = (unsigned long)&frame->info;
 445     env->regs[R_EDX] = (unsigned long)&frame->uc;
 446 #endif
 447
 448     cpu_x86_load_seg(env, R_DS, __USER_DS);
 449     cpu_x86_load_seg(env, R_ES, __USER_DS);
 450     cpu_x86_load_seg(env, R_CS, __USER_CS);
 451     cpu_x86_load_seg(env, R_SS, __USER_DS);
 452     env->eflags &= ~TF_MASK;
 453
 454     unlock_user_struct(frame, frame_addr, 1);
 455
 456     return;
 457
 458 give_sigsegv:
 459     force_sigsegv(sig);
 460 }
 461
 462 static int
 463 restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc)
 464 {
 465     unsigned int err = 0;
 466     abi_ulong fpstate_addr;
 467     unsigned int tmpflags;
 468
 469 #ifndef TARGET_X86_64
 470     cpu_x86_load_seg(env, R_GS, tswap16(sc->gs));
 471     cpu_x86_load_seg(env, R_FS, tswap16(sc->fs));
 472     cpu_x86_load_seg(env, R_ES, tswap16(sc->es));
 473     cpu_x86_load_seg(env, R_DS, tswap16(sc->ds));
 474
 475     env->regs[R_EDI] = tswapl(sc->edi);
 476     env->regs[R_ESI] = tswapl(sc->esi);
 477     env->regs[R_EBP] = tswapl(sc->ebp);
 478     env->regs[R_ESP] = tswapl(sc->esp);
 479     env->regs[R_EBX] = tswapl(sc->ebx);
 480     env->regs[R_EDX] = tswapl(sc->edx);
 481     env->regs[R_ECX] = tswapl(sc->ecx);
 482     env->regs[R_EAX] = tswapl(sc->eax);
 483
 484     env->eip = tswapl(sc->eip);
 485 #else
 486     env->regs[8] = tswapl(sc->r8);
 487     env->regs[9] = tswapl(sc->r9);
 488     env->regs[10] = tswapl(sc->r10);
 489     env->regs[11] = tswapl(sc->r11);
 490     env->regs[12] = tswapl(sc->r12);
 491     env->regs[13] = tswapl(sc->r13);
 492     env->regs[14] = tswapl(sc->r14);
 493     env->regs[15] = tswapl(sc->r15);
 494
 495     env->regs[R_EDI] = tswapl(sc->rdi);
 496     env->regs[R_ESI] = tswapl(sc->rsi);
 497     env->regs[R_EBP] = tswapl(sc->rbp);
 498     env->regs[R_EBX] = tswapl(sc->rbx);
 499     env->regs[R_EDX] = tswapl(sc->rdx);
 500     env->regs[R_EAX] = tswapl(sc->rax);
 501     env->regs[R_ECX] = tswapl(sc->rcx);
 502     env->regs[R_ESP] = tswapl(sc->rsp);
 503
 504     env->eip = tswapl(sc->rip);
 505 #endif
 506
 507     cpu_x86_load_seg(env, R_CS, lduw_p(&sc->cs) | 3);
 508     cpu_x86_load_seg(env, R_SS, lduw_p(&sc->ss) | 3);
 509
 510     tmpflags = tswapl(sc->eflags);
 511     env->eflags = (env->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
 512     //          regs->orig_eax = -1;            /* disable syscall checks */
 513
 514     fpstate_addr = tswapl(sc->fpstate);
 515     if (fpstate_addr != 0) {
 516         if (!access_ok(env_cpu(env), VERIFY_READ, fpstate_addr,
 517                        sizeof(struct target_fpstate))) {
 518             goto badframe;
 519         }
 520 #ifndef TARGET_X86_64
 521         cpu_x86_frstor(env, fpstate_addr, 1);
 522 #else
 523         cpu_x86_fxrstor(env, fpstate_addr);
 524 #endif
 525     }
 526
 527     return err;
 528 badframe:
 529     return 1;
 530 }
 531
 532 /* Note: there is no sigreturn on x86_64, there is only rt_sigreturn */
 533 #ifndef TARGET_X86_64
 534 long do_sigreturn(CPUX86State *env)
 535 {
 536     struct sigframe *frame;
 537     abi_ulong frame_addr = env->regs[R_ESP] - 8;
 538     target_sigset_t target_set;
 539     sigset_t set;
 540     int i;
 541
 542     trace_user_do_sigreturn(env, frame_addr);
 543     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
 544         goto badframe;
 545     /* set blocked signals */
 546     __get_user(target_set.sig[0], &frame->sc.oldmask);
 547     for(i = 1; i < TARGET_NSIG_WORDS; i++) {
 548         __get_user(target_set.sig[i], &frame->extramask[i - 1]);
 549     }
 550
 551     target_to_host_sigset_internal(&set, &target_set);
 552     set_sigmask(&set);
 553
 554     /* restore registers */
 555     if (restore_sigcontext(env, &frame->sc))
 556         goto badframe;
 557     unlock_user_struct(frame, frame_addr, 0);
 558     return -TARGET_QEMU_ESIGRETURN;
 559
 560 badframe:
 561     unlock_user_struct(frame, frame_addr, 0);
 562     force_sig(TARGET_SIGSEGV);
 563     return -TARGET_QEMU_ESIGRETURN;
 564 }
 565 #endif
 566
 567 long do_rt_sigreturn(CPUX86State *env)
 568 {
 569     abi_ulong frame_addr;
 570     struct rt_sigframe *frame;
 571     sigset_t set;
 572
 573     frame_addr = env->regs[R_ESP] - sizeof(abi_ulong);
 574     trace_user_do_rt_sigreturn(env, frame_addr);
 575     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
 576         goto badframe;
 577     target_to_host_sigset(&set, &frame->uc.tuc_sigmask);
 578     set_sigmask(&set);
 579
 580     if (restore_sigcontext(env, &frame->uc.tuc_mcontext)) {
 581         goto badframe;
 582     }
 583
 584     if (do_sigaltstack(frame_addr + offsetof(struct rt_sigframe, uc.tuc_stack), 0,
 585                        get_sp_from_cpustate(env)) == -EFAULT) {
 586         goto badframe;
 587     }
 588
 589     unlock_user_struct(frame, frame_addr, 0);
 590     return -TARGET_QEMU_ESIGRETURN;
 591
 592 badframe:
 593     unlock_user_struct(frame, frame_addr, 0);
 594     force_sig(TARGET_SIGSEGV);
 595     return -TARGET_QEMU_ESIGRETURN;
 596 }