LXR linux/arch/x86/um/signal.c

   1/*
   2 * Copyright (C) 2003 PathScale, Inc.
   3 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4 * Licensed under the GPL
   5 */
   6
   7
   8#include <linux/personality.h>
   9#include <linux/ptrace.h>
  10#include <linux/kernel.h>
  11#include <asm/unistd.h>
  12#include <linux/uaccess.h>
  13#include <asm/ucontext.h>
  14#include <frame_kern.h>
  15#include <skas.h>
  16
  17#ifdef CONFIG_X86_32
  18
  19/*
  20 * FPU tag word conversions.
  21 */
  22
  23static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
  24{
  25        unsigned int tmp; /* to avoid 16 bit prefixes in the code */
  26
  27        /* Transform each pair of bits into 01 (valid) or 00 (empty) */
  28        tmp = ~twd;
  29        tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
  30        /* and move the valid bits to the lower byte. */
  31        tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
  32        tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
  33        tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
  34        return tmp;
  35}
  36
  37static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
  38{
  39        struct _fpxreg *st = NULL;
  40        unsigned long twd = (unsigned long) fxsave->twd;
  41        unsigned long tag;
  42        unsigned long ret = 0xffff0000;
  43        int i;
  44
  45#define FPREG_ADDR(f, n)        ((char *)&(f)->st_space + (n) * 16)
  46
  47        for (i = 0; i < 8; i++) {
  48                if (twd & 0x1) {
  49                        st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);
  50
  51                        switch (st->exponent & 0x7fff) {
  52                        case 0x7fff:
  53                                tag = 2;                /* Special */
  54                                break;
  55                        case 0x0000:
  56                                if ( !st->significand[0] &&
  57                                     !st->significand[1] &&
  58                                     !st->significand[2] &&
  59                                     !st->significand[3] ) {
  60                                        tag = 1;        /* Zero */
  61                                } else {
  62                                        tag = 2;        /* Special */
  63                                }
  64                                break;
  65                        default:
  66                                if (st->significand[3] & 0x8000) {
  67                                        tag = 0;        /* Valid */
  68                                } else {
  69                                        tag = 2;        /* Special */
  70                                }
  71                                break;
  72                        }
  73                } else {
  74                        tag = 3;                        /* Empty */
  75                }
  76                ret |= (tag << (2 * i));
  77                twd = twd >> 1;
  78        }
  79        return ret;
  80}
  81
  82static int convert_fxsr_to_user(struct _fpstate __user *buf,
  83                                struct user_fxsr_struct *fxsave)
  84{
  85        unsigned long env[7];
  86        struct _fpreg __user *to;
  87        struct _fpxreg *from;
  88        int i;
  89
  90        env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
  91        env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
  92        env[2] = twd_fxsr_to_i387(fxsave);
  93        env[3] = fxsave->fip;
  94        env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
  95        env[5] = fxsave->foo;
  96        env[6] = fxsave->fos;
  97
  98        if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
  99                return 1;
 100
 101        to = &buf->_st[0];
 102        from = (struct _fpxreg *) &fxsave->st_space[0];
 103        for (i = 0; i < 8; i++, to++, from++) {
 104                unsigned long __user *t = (unsigned long __user *)to;
 105                unsigned long *f = (unsigned long *)from;
 106
 107                if (__put_user(*f, t) ||
 108                                __put_user(*(f + 1), t + 1) ||
 109                                __put_user(from->exponent, &to->exponent))
 110                        return 1;
 111        }
 112        return 0;
 113}
 114
 115static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
 116                                  struct _fpstate __user *buf)
 117{
 118        unsigned long env[7];
 119        struct _fpxreg *to;
 120        struct _fpreg __user *from;
 121        int i;
 122
 123        if (copy_from_user( env, buf, 7 * sizeof(long)))
 124                return 1;
 125
 126        fxsave->cwd = (unsigned short)(env[0] & 0xffff);
 127        fxsave->swd = (unsigned short)(env[1] & 0xffff);
 128        fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
 129        fxsave->fip = env[3];
 130        fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
 131        fxsave->fcs = (env[4] & 0xffff);
 132        fxsave->foo = env[5];
 133        fxsave->fos = env[6];
 134
 135        to = (struct _fpxreg *) &fxsave->st_space[0];
 136        from = &buf->_st[0];
 137        for (i = 0; i < 8; i++, to++, from++) {
 138                unsigned long *t = (unsigned long *)to;
 139                unsigned long __user *f = (unsigned long __user *)from;
 140
 141                if (__get_user(*t, f) ||
 142                    __get_user(*(t + 1), f + 1) ||
 143                    __get_user(to->exponent, &from->exponent))
 144                        return 1;
 145        }
 146        return 0;
 147}
 148
 149extern int have_fpx_regs;
 150
 151#endif
 152
 153static int copy_sc_from_user(struct pt_regs *regs,
 154                             struct sigcontext __user *from)
 155{
 156        struct sigcontext sc;
 157        int err, pid;
 158
 159        /* Always make any pending restarted system calls return -EINTR */
 160        current->restart_block.fn = do_no_restart_syscall;
 161
 162        err = copy_from_user(&sc, from, sizeof(sc));
 163        if (err)
 164                return err;
 165
 166#define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname
 167
 168#ifdef CONFIG_X86_32
 169        GETREG(GS, gs);
 170        GETREG(FS, fs);
 171        GETREG(ES, es);
 172        GETREG(DS, ds);
 173#endif
 174        GETREG(DI, di);
 175        GETREG(SI, si);
 176        GETREG(BP, bp);
 177        GETREG(SP, sp);
 178        GETREG(BX, bx);
 179        GETREG(DX, dx);
 180        GETREG(CX, cx);
 181        GETREG(AX, ax);
 182        GETREG(IP, ip);
 183
 184#ifdef CONFIG_X86_64
 185        GETREG(R8, r8);
 186        GETREG(R9, r9);
 187        GETREG(R10, r10);
 188        GETREG(R11, r11);
 189        GETREG(R12, r12);
 190        GETREG(R13, r13);
 191        GETREG(R14, r14);
 192        GETREG(R15, r15);
 193#endif
 194
 195        GETREG(CS, cs);
 196        GETREG(EFLAGS, flags);
 197#ifdef CONFIG_X86_32
 198        GETREG(SS, ss);
 199#endif
 200
 201#undef GETREG
 202
 203        pid = userspace_pid[current_thread_info()->cpu];
 204#ifdef CONFIG_X86_32
 205        if (have_fpx_regs) {
 206                struct user_fxsr_struct fpx;
 207
 208                err = copy_from_user(&fpx,
 209                        &((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
 210                                     sizeof(struct user_fxsr_struct));
 211                if (err)
 212                        return 1;
 213
 214                err = convert_fxsr_from_user(&fpx, (void *)sc.fpstate);
 215                if (err)
 216                        return 1;
 217
 218                err = restore_fpx_registers(pid, (unsigned long *) &fpx);
 219                if (err < 0) {
 220                        printk(KERN_ERR "copy_sc_from_user - "
 221                               "restore_fpx_registers failed, errno = %d\n",
 222                               -err);
 223                        return 1;
 224                }
 225        } else
 226#endif
 227        {
 228                err = copy_from_user(regs->regs.fp, (void *)sc.fpstate,
 229                                     sizeof(struct _xstate));
 230                if (err)
 231                        return 1;
 232        }
 233        return 0;
 234}
 235
 236static int copy_sc_to_user(struct sigcontext __user *to,
 237                           struct _xstate __user *to_fp, struct pt_regs *regs,
 238                           unsigned long mask)
 239{
 240        struct sigcontext sc;
 241        struct faultinfo * fi = &current->thread.arch.faultinfo;
 242        int err, pid;
 243        memset(&sc, 0, sizeof(struct sigcontext));
 244
 245#define PUTREG(regno, regname) sc.regname = regs->regs.gp[HOST_##regno]
 246
 247#ifdef CONFIG_X86_32
 248        PUTREG(GS, gs);
 249        PUTREG(FS, fs);
 250        PUTREG(ES, es);
 251        PUTREG(DS, ds);
 252#endif
 253        PUTREG(DI, di);
 254        PUTREG(SI, si);
 255        PUTREG(BP, bp);
 256        PUTREG(SP, sp);
 257        PUTREG(BX, bx);
 258        PUTREG(DX, dx);
 259        PUTREG(CX, cx);
 260        PUTREG(AX, ax);
 261#ifdef CONFIG_X86_64
 262        PUTREG(R8, r8);
 263        PUTREG(R9, r9);
 264        PUTREG(R10, r10);
 265        PUTREG(R11, r11);
 266        PUTREG(R12, r12);
 267        PUTREG(R13, r13);
 268        PUTREG(R14, r14);
 269        PUTREG(R15, r15);
 270#endif
 271
 272        sc.cr2 = fi->cr2;
 273        sc.err = fi->error_code;
 274        sc.trapno = fi->trap_no;
 275        PUTREG(IP, ip);
 276        PUTREG(CS, cs);
 277        PUTREG(EFLAGS, flags);
 278#ifdef CONFIG_X86_32
 279        PUTREG(SP, sp_at_signal);
 280        PUTREG(SS, ss);
 281#endif
 282#undef PUTREG
 283        sc.oldmask = mask;
 284        sc.fpstate = (unsigned long)to_fp;
 285
 286        err = copy_to_user(to, &sc, sizeof(struct sigcontext));
 287        if (err)
 288                return 1;
 289
 290        pid = userspace_pid[current_thread_info()->cpu];
 291
 292#ifdef CONFIG_X86_32
 293        if (have_fpx_regs) {
 294                struct user_fxsr_struct fpx;
 295
 296                err = save_fpx_registers(pid, (unsigned long *) &fpx);
 297                if (err < 0){
 298                        printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
 299                               "failed, errno = %d\n", err);
 300                        return 1;
 301                }
 302
 303                err = convert_fxsr_to_user(&to_fp->fpstate, &fpx);
 304                if (err)
 305                        return 1;
 306
 307                err |= __put_user(fpx.swd, &to_fp->fpstate.status);
 308                err |= __put_user(X86_FXSR_MAGIC, &to_fp->fpstate.magic);
 309                if (err)
 310                        return 1;
 311
 312                if (copy_to_user(&to_fp->fpstate._fxsr_env[0], &fpx,
 313                                 sizeof(struct user_fxsr_struct)))
 314                        return 1;
 315        } else
 316#endif
 317        {
 318                if (copy_to_user(to_fp, regs->regs.fp, sizeof(struct _xstate)))
 319                        return 1;
 320        }
 321
 322        return 0;
 323}
 324
 325#ifdef CONFIG_X86_32
 326static int copy_ucontext_to_user(struct ucontext __user *uc,
 327                                 struct _xstate __user *fp, sigset_t *set,
 328                                 unsigned long sp)
 329{
 330        int err = 0;
 331
 332        err |= __save_altstack(&uc->uc_stack, sp);
 333        err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, 0);
 334        err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
 335        return err;
 336}
 337
 338struct sigframe
 339{
 340        char __user *pretcode;
 341        int sig;
 342        struct sigcontext sc;
 343        struct _xstate fpstate;
 344        unsigned long extramask[_NSIG_WORDS-1];
 345        char retcode[8];
 346};
 347
 348struct rt_sigframe
 349{
 350        char __user *pretcode;
 351        int sig;
 352        struct siginfo __user *pinfo;
 353        void __user *puc;
 354        struct siginfo info;
 355        struct ucontext uc;
 356        struct _xstate fpstate;
 357        char retcode[8];
 358};
 359
 360int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig,
 361                          struct pt_regs *regs, sigset_t *mask)
 362{
 363        struct sigframe __user *frame;
 364        void __user *restorer;
 365        int err = 0, sig = ksig->sig;
 366
 367        /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
 368        stack_top = ((stack_top + 4) & -16UL) - 4;
 369        frame = (struct sigframe __user *) stack_top - 1;
 370        if (!access_ok(frame, sizeof(*frame)))
 371                return 1;
 372
 373        restorer = frame->retcode;
 374        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 375                restorer = ksig->ka.sa.sa_restorer;
 376
 377        err |= __put_user(restorer, &frame->pretcode);
 378        err |= __put_user(sig, &frame->sig);
 379        err |= copy_sc_to_user(&frame->sc, &frame->fpstate, regs, mask->sig[0]);
 380        if (_NSIG_WORDS > 1)
 381                err |= __copy_to_user(&frame->extramask, &mask->sig[1],
 382                                      sizeof(frame->extramask));
 383
 384        /*
 385         * This is popl %eax ; movl $,%eax ; int $0x80
 386         *
 387         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 388         * reasons and because gdb uses it as a signature to notice
 389         * signal handler stack frames.
 390         */
 391        err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 392        err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 393        err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 394
 395        if (err)
 396                return err;
 397
 398        PT_REGS_SP(regs) = (unsigned long) frame;
 399        PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
 400        PT_REGS_AX(regs) = (unsigned long) sig;
 401        PT_REGS_DX(regs) = (unsigned long) 0;
 402        PT_REGS_CX(regs) = (unsigned long) 0;
 403        return 0;
 404}
 405
 406int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 407                          struct pt_regs *regs, sigset_t *mask)
 408{
 409        struct rt_sigframe __user *frame;
 410        void __user *restorer;
 411        int err = 0, sig = ksig->sig;
 412
 413        stack_top &= -8UL;
 414        frame = (struct rt_sigframe __user *) stack_top - 1;
 415        if (!access_ok(frame, sizeof(*frame)))
 416                return 1;
 417
 418        restorer = frame->retcode;
 419        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 420                restorer = ksig->ka.sa.sa_restorer;
 421
 422        err |= __put_user(restorer, &frame->pretcode);
 423        err |= __put_user(sig, &frame->sig);
 424        err |= __put_user(&frame->info, &frame->pinfo);
 425        err |= __put_user(&frame->uc, &frame->puc);
 426        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 427        err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
 428                                        PT_REGS_SP(regs));
 429
 430        /*
 431         * This is movl $,%eax ; int $0x80
 432         *
 433         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 434         * reasons and because gdb uses it as a signature to notice
 435         * signal handler stack frames.
 436         */
 437        err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 438        err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 439        err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 440
 441        if (err)
 442                return err;
 443
 444        PT_REGS_SP(regs) = (unsigned long) frame;
 445        PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
 446        PT_REGS_AX(regs) = (unsigned long) sig;
 447        PT_REGS_DX(regs) = (unsigned long) &frame->info;
 448        PT_REGS_CX(regs) = (unsigned long) &frame->uc;
 449        return 0;
 450}
 451
 452long sys_sigreturn(void)
 453{
 454        unsigned long sp = PT_REGS_SP(&current->thread.regs);
 455        struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
 456        sigset_t set;
 457        struct sigcontext __user *sc = &frame->sc;
 458        int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 459
 460        if (copy_from_user(&set.sig[0], &sc->oldmask, sizeof(set.sig[0])) ||
 461            copy_from_user(&set.sig[1], frame->extramask, sig_size))
 462                goto segfault;
 463
 464        set_current_blocked(&set);
 465
 466        if (copy_sc_from_user(&current->thread.regs, sc))
 467                goto segfault;
 468
 469        /* Avoid ERESTART handling */
 470        PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 471        return PT_REGS_SYSCALL_RET(&current->thread.regs);
 472
 473 segfault:
 474        force_sig(SIGSEGV);
 475        return 0;
 476}
 477
 478#else
 479
 480struct rt_sigframe
 481{
 482        char __user *pretcode;
 483        struct ucontext uc;
 484        struct siginfo info;
 485        struct _xstate fpstate;
 486};
 487
 488int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 489                          struct pt_regs *regs, sigset_t *set)
 490{
 491        struct rt_sigframe __user *frame;
 492        int err = 0, sig = ksig->sig;
 493        unsigned long fp_to;
 494
 495        frame = (struct rt_sigframe __user *)
 496                round_down(stack_top - sizeof(struct rt_sigframe), 16);
 497        /* Subtract 128 for a red zone and 8 for proper alignment */
 498        frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);
 499
 500        if (!access_ok(frame, sizeof(*frame)))
 501                goto out;
 502
 503        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 504                err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 505                if (err)
 506                        goto out;
 507        }
 508
 509        /* Create the ucontext.  */
 510        err |= __put_user(0, &frame->uc.uc_flags);
 511        err |= __put_user(0, &frame->uc.uc_link);
 512        err |= __save_altstack(&frame->uc.uc_stack, PT_REGS_SP(regs));
 513        err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
 514                               set->sig[0]);
 515
 516        fp_to = (unsigned long)&frame->fpstate;
 517
 518        err |= __put_user(fp_to, &frame->uc.uc_mcontext.fpstate);
 519        if (sizeof(*set) == 16) {
 520                err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 521                err |= __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 522        }
 523        else
 524                err |= __copy_to_user(&frame->uc.uc_sigmask, set,
 525                                      sizeof(*set));
 526
 527        /*
 528         * Set up to return from userspace.  If provided, use a stub
 529         * already in userspace.
 530         */
 531        /* x86-64 should always use SA_RESTORER. */
 532        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 533                err |= __put_user((void *)ksig->ka.sa.sa_restorer,
 534                                  &frame->pretcode);
 535        else
 536                /* could use a vstub here */
 537                return err;
 538
 539        if (err)
 540                return err;
 541
 542        PT_REGS_SP(regs) = (unsigned long) frame;
 543        PT_REGS_DI(regs) = sig;
 544        /* In case the signal handler was declared without prototypes */
 545        PT_REGS_AX(regs) = 0;
 546
 547        /*
 548         * This also works for non SA_SIGINFO handlers because they expect the
 549         * next argument after the signal number on the stack.
 550         */
 551        PT_REGS_SI(regs) = (unsigned long) &frame->info;
 552        PT_REGS_DX(regs) = (unsigned long) &frame->uc;
 553        PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
 554 out:
 555        return err;
 556}
 557#endif
 558
 559long sys_rt_sigreturn(void)
 560{
 561        unsigned long sp = PT_REGS_SP(&current->thread.regs);
 562        struct rt_sigframe __user *frame =
 563                (struct rt_sigframe __user *)(sp - sizeof(long));
 564        struct ucontext __user *uc = &frame->uc;
 565        sigset_t set;
 566
 567        if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
 568                goto segfault;
 569
 570        set_current_blocked(&set);
 571
 572        if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 573                goto segfault;
 574
 575        /* Avoid ERESTART handling */
 576        PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 577        return PT_REGS_SYSCALL_RET(&current->thread.regs);
 578
 579 segfault:
 580        force_sig(SIGSEGV);
 581        return 0;
 582}
 583