LXR qemu/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
  26struct target_fpreg {
  27    uint16_t significand[4];
  28    uint16_t exponent;
  29};
  30
  31struct target_fpxreg {
  32    uint16_t significand[4];
  33    uint16_t exponent;
  34    uint16_t padding[3];
  35};
  36
  37struct target_xmmreg {
  38    uint32_t element[4];
  39};
  40
  41struct 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
  63struct 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
  84struct 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
 109struct 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 */
 152struct 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
 161struct 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
 170struct 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
 183struct 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 */
 197static 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 = CPU(x86_env_get_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
 279static inline abi_ulong
 280get_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() */
 313void 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
 366give_sigsegv:
 367    force_sigsegv(sig);
 368}
 369#endif
 370
 371/* compare linux/arch/x86/kernel/signal.c:setup_rt_frame() */
 372void 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
 458give_sigsegv:
 459    force_sigsegv(sig);
 460}
 461
 462static int
 463restore_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(VERIFY_READ, fpstate_addr,
 517                       sizeof(struct target_fpstate)))
 518            goto badframe;
 519#ifndef TARGET_X86_64
 520        cpu_x86_frstor(env, fpstate_addr, 1);
 521#else
 522        cpu_x86_fxrstor(env, fpstate_addr);
 523#endif
 524    }
 525
 526    return err;
 527badframe:
 528    return 1;
 529}
 530
 531/* Note: there is no sigreturn on x86_64, there is only rt_sigreturn */
 532#ifndef TARGET_X86_64
 533long do_sigreturn(CPUX86State *env)
 534{
 535    struct sigframe *frame;
 536    abi_ulong frame_addr = env->regs[R_ESP] - 8;
 537    target_sigset_t target_set;
 538    sigset_t set;
 539    int i;
 540
 541    trace_user_do_sigreturn(env, frame_addr);
 542    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
 543        goto badframe;
 544    /* set blocked signals */
 545    __get_user(target_set.sig[0], &frame->sc.oldmask);
 546    for(i = 1; i < TARGET_NSIG_WORDS; i++) {
 547        __get_user(target_set.sig[i], &frame->extramask[i - 1]);
 548    }
 549
 550    target_to_host_sigset_internal(&set, &target_set);
 551    set_sigmask(&set);
 552
 553    /* restore registers */
 554    if (restore_sigcontext(env, &frame->sc))
 555        goto badframe;
 556    unlock_user_struct(frame, frame_addr, 0);
 557    return -TARGET_QEMU_ESIGRETURN;
 558
 559badframe:
 560    unlock_user_struct(frame, frame_addr, 0);
 561    force_sig(TARGET_SIGSEGV);
 562    return -TARGET_QEMU_ESIGRETURN;
 563}
 564#endif
 565
 566long do_rt_sigreturn(CPUX86State *env)
 567{
 568    abi_ulong frame_addr;
 569    struct rt_sigframe *frame;
 570    sigset_t set;
 571
 572    frame_addr = env->regs[R_ESP] - sizeof(abi_ulong);
 573    trace_user_do_rt_sigreturn(env, frame_addr);
 574    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
 575        goto badframe;
 576    target_to_host_sigset(&set, &frame->uc.tuc_sigmask);
 577    set_sigmask(&set);
 578
 579    if (restore_sigcontext(env, &frame->uc.tuc_mcontext)) {
 580        goto badframe;
 581    }
 582
 583    if (do_sigaltstack(frame_addr + offsetof(struct rt_sigframe, uc.tuc_stack), 0,
 584                       get_sp_from_cpustate(env)) == -EFAULT) {
 585        goto badframe;
 586    }
 587
 588    unlock_user_struct(frame, frame_addr, 0);
 589    return -TARGET_QEMU_ESIGRETURN;
 590
 591badframe:
 592    unlock_user_struct(frame, frame_addr, 0);
 593    force_sig(TARGET_SIGSEGV);
 594    return -TARGET_QEMU_ESIGRETURN;
 595}
 596