arch/um/sys-i386/signal.c

   1 /*
   2  * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <linux/ptrace.h>
   7 #include <asm/unistd.h>
   8 #include <asm/uaccess.h>
   9 #include <asm/ucontext.h>
  10 #include "frame_kern.h"
  11 #include "skas.h"
  12
  13 void copy_sc(struct uml_pt_regs *regs, void *from)
  14 {
  15         struct sigcontext *sc = from;
  16
  17         REGS_GS(regs->gp) = sc->gs;
  18         REGS_FS(regs->gp) = sc->fs;
  19         REGS_ES(regs->gp) = sc->es;
  20         REGS_DS(regs->gp) = sc->ds;
  21         REGS_EDI(regs->gp) = sc->di;
  22         REGS_ESI(regs->gp) = sc->si;
  23         REGS_EBP(regs->gp) = sc->bp;
  24         REGS_SP(regs->gp) = sc->sp;
  25         REGS_EBX(regs->gp) = sc->bx;
  26         REGS_EDX(regs->gp) = sc->dx;
  27         REGS_ECX(regs->gp) = sc->cx;
  28         REGS_EAX(regs->gp) = sc->ax;
  29         REGS_IP(regs->gp) = sc->ip;
  30         REGS_CS(regs->gp) = sc->cs;
  31         REGS_EFLAGS(regs->gp) = sc->flags;
  32         REGS_SS(regs->gp) = sc->ss;
  33 }
  34
  35 /*
  36  * FPU tag word conversions.
  37  */
  38
  39 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
  40 {
  41         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
  42
  43         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
  44         tmp = ~twd;
  45         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
  46         /* and move the valid bits to the lower byte. */
  47         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
  48         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
  49         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
  50         return tmp;
  51 }
  52
  53 static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
  54 {
  55         struct _fpxreg *st = NULL;
  56         unsigned long twd = (unsigned long) fxsave->twd;
  57         unsigned long tag;
  58         unsigned long ret = 0xffff0000;
  59         int i;
  60
  61 #define FPREG_ADDR(f, n)        ((char *)&(f)->st_space + (n) * 16);
  62
  63         for (i = 0; i < 8; i++) {
  64                 if (twd & 0x1) {
  65                         st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);
  66
  67                         switch (st->exponent & 0x7fff) {
  68                         case 0x7fff:
  69                                 tag = 2;                /* Special */
  70                                 break;
  71                         case 0x0000:
  72                                 if ( !st->significand[0] &&
  73                                      !st->significand[1] &&
  74                                      !st->significand[2] &&
  75                                      !st->significand[3] ) {
  76                                         tag = 1;        /* Zero */
  77                                 } else {
  78                                         tag = 2;        /* Special */
  79                                 }
  80                                 break;
  81                         default:
  82                                 if (st->significand[3] & 0x8000) {
  83                                         tag = 0;        /* Valid */
  84                                 } else {
  85                                         tag = 2;        /* Special */
  86                                 }
  87                                 break;
  88                         }
  89                 } else {
  90                         tag = 3;                        /* Empty */
  91                 }
  92                 ret |= (tag << (2 * i));
  93                 twd = twd >> 1;
  94         }
  95         return ret;
  96 }
  97
  98 static int convert_fxsr_to_user(struct _fpstate __user *buf,
  99                                 struct user_fxsr_struct *fxsave)
 100 {
 101         unsigned long env[7];
 102         struct _fpreg __user *to;
 103         struct _fpxreg *from;
 104         int i;
 105
 106         env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
 107         env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
 108         env[2] = twd_fxsr_to_i387(fxsave);
 109         env[3] = fxsave->fip;
 110         env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
 111         env[5] = fxsave->foo;
 112         env[6] = fxsave->fos;
 113
 114         if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
 115                 return 1;
 116
 117         to = &buf->_st[0];
 118         from = (struct _fpxreg *) &fxsave->st_space[0];
 119         for (i = 0; i < 8; i++, to++, from++) {
 120                 unsigned long __user *t = (unsigned long __user *)to;
 121                 unsigned long *f = (unsigned long *)from;
 122
 123                 if (__put_user(*f, t) ||
 124                                 __put_user(*(f + 1), t + 1) ||
 125                                 __put_user(from->exponent, &to->exponent))
 126                         return 1;
 127         }
 128         return 0;
 129 }
 130
 131 static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
 132                                   struct _fpstate __user *buf)
 133 {
 134         unsigned long env[7];
 135         struct _fpxreg *to;
 136         struct _fpreg __user *from;
 137         int i;
 138
 139         if (copy_from_user( env, buf, 7 * sizeof(long)))
 140                 return 1;
 141
 142         fxsave->cwd = (unsigned short)(env[0] & 0xffff);
 143         fxsave->swd = (unsigned short)(env[1] & 0xffff);
 144         fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
 145         fxsave->fip = env[3];
 146         fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
 147         fxsave->fcs = (env[4] & 0xffff);
 148         fxsave->foo = env[5];
 149         fxsave->fos = env[6];
 150
 151         to = (struct _fpxreg *) &fxsave->st_space[0];
 152         from = &buf->_st[0];
 153         for (i = 0; i < 8; i++, to++, from++) {
 154                 unsigned long *t = (unsigned long *)to;
 155                 unsigned long __user *f = (unsigned long __user *)from;
 156
 157                 if (__get_user(*t, f) ||
 158                     __get_user(*(t + 1), f + 1) ||
 159                     __get_user(to->exponent, &from->exponent))
 160                         return 1;
 161         }
 162         return 0;
 163 }
 164
 165 extern int have_fpx_regs;
 166
 167 static int copy_sc_from_user(struct pt_regs *regs,
 168                              struct sigcontext __user *from)
 169 {
 170         struct sigcontext sc;
 171         int err;
 172
 173         err = copy_from_user(&sc, from, sizeof(sc));
 174         if (err)
 175                 return err;
 176
 177         copy_sc(&regs->regs, &sc);
 178         if (have_fpx_regs) {
 179                 struct user_fxsr_struct fpx;
 180
 181                 err = copy_from_user(&fpx, &sc.fpstate->_fxsr_env[0],
 182                                      sizeof(struct user_fxsr_struct));
 183                 if (err)
 184                         return 1;
 185
 186                 err = convert_fxsr_from_user(&fpx, sc.fpstate);
 187                 if (err)
 188                         return 1;
 189
 190                 err = restore_fpx_registers(userspace_pid[current_thread->cpu],
 191                                             (unsigned long *) &fpx);
 192                 if (err < 0) {
 193                         printk(KERN_ERR "copy_sc_from_user - "
 194                                "restore_fpx_registers failed, errno = %d\n",
 195                                -err);
 196                         return 1;
 197                 }
 198         }
 199         else {
 200                 struct user_i387_struct fp;
 201
 202                 err = copy_from_user(&fp, sc.fpstate,
 203                                      sizeof(struct user_i387_struct));
 204                 if (err)
 205                         return 1;
 206
 207                 err = restore_fp_registers(userspace_pid[current_thread->cpu],
 208                                            (unsigned long *) &fp);
 209                 if (err < 0) {
 210                         printk(KERN_ERR "copy_sc_from_user - "
 211                                "restore_fp_registers failed, errno = %d\n",
 212                                -err);
 213                         return 1;
 214                 }
 215         }
 216
 217         return 0;
 218 }
 219
 220 static int copy_sc_to_user(struct sigcontext __user *to,
 221                            struct _fpstate __user *to_fp, struct pt_regs *regs,
 222                            unsigned long sp)
 223 {
 224         struct sigcontext sc;
 225         struct faultinfo * fi = &current->thread.arch.faultinfo;
 226         int err;
 227
 228         sc.gs = REGS_GS(regs->regs.gp);
 229         sc.fs = REGS_FS(regs->regs.gp);
 230         sc.es = REGS_ES(regs->regs.gp);
 231         sc.ds = REGS_DS(regs->regs.gp);
 232         sc.di = REGS_EDI(regs->regs.gp);
 233         sc.si = REGS_ESI(regs->regs.gp);
 234         sc.bp = REGS_EBP(regs->regs.gp);
 235         sc.sp = sp;
 236         sc.bx = REGS_EBX(regs->regs.gp);
 237         sc.dx = REGS_EDX(regs->regs.gp);
 238         sc.cx = REGS_ECX(regs->regs.gp);
 239         sc.ax = REGS_EAX(regs->regs.gp);
 240         sc.ip = REGS_IP(regs->regs.gp);
 241         sc.cs = REGS_CS(regs->regs.gp);
 242         sc.flags = REGS_EFLAGS(regs->regs.gp);
 243         sc.sp_at_signal = regs->regs.gp[UESP];
 244         sc.ss = regs->regs.gp[SS];
 245         sc.cr2 = fi->cr2;
 246         sc.err = fi->error_code;
 247         sc.trapno = fi->trap_no;
 248
 249         to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
 250         sc.fpstate = to_fp;
 251
 252         if (have_fpx_regs) {
 253                 struct user_fxsr_struct fpx;
 254
 255                 err = save_fpx_registers(userspace_pid[current_thread->cpu],
 256                                          (unsigned long *) &fpx);
 257                 if (err < 0){
 258                         printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
 259                                "failed, errno = %d\n", err);
 260                         return 1;
 261                 }
 262
 263                 err = convert_fxsr_to_user(to_fp, &fpx);
 264                 if (err)
 265                         return 1;
 266
 267                 err |= __put_user(fpx.swd, &to_fp->status);
 268                 err |= __put_user(X86_FXSR_MAGIC, &to_fp->magic);
 269                 if (err)
 270                         return 1;
 271
 272                 if (copy_to_user(&to_fp->_fxsr_env[0], &fpx,
 273                                  sizeof(struct user_fxsr_struct)))
 274                         return 1;
 275         }
 276         else {
 277                 struct user_i387_struct fp;
 278
 279                 err = save_fp_registers(userspace_pid[current_thread->cpu],
 280                                         (unsigned long *) &fp);
 281                 if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
 282                         return 1;
 283         }
 284
 285         return copy_to_user(to, &sc, sizeof(sc));
 286 }
 287
 288 static int copy_ucontext_to_user(struct ucontext __user *uc,
 289                                  struct _fpstate __user *fp, sigset_t *set,
 290                                  unsigned long sp)
 291 {
 292         int err = 0;
 293
 294         err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
 295         err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
 296         err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
 297         err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
 298         err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
 299         return err;
 300 }
 301
 302 struct sigframe
 303 {
 304         char __user *pretcode;
 305         int sig;
 306         struct sigcontext sc;
 307         struct _fpstate fpstate;
 308         unsigned long extramask[_NSIG_WORDS-1];
 309         char retcode[8];
 310 };
 311
 312 struct rt_sigframe
 313 {
 314         char __user *pretcode;
 315         int sig;
 316         struct siginfo __user *pinfo;
 317         void __user *puc;
 318         struct siginfo info;
 319         struct ucontext uc;
 320         struct _fpstate fpstate;
 321         char retcode[8];
 322 };
 323
 324 int setup_signal_stack_sc(unsigned long stack_top, int sig,
 325                           struct k_sigaction *ka, struct pt_regs *regs,
 326                           sigset_t *mask)
 327 {
 328         struct sigframe __user *frame;
 329         void __user *restorer;
 330         unsigned long save_sp = PT_REGS_SP(regs);
 331         int err = 0;
 332
 333         /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
 334         stack_top = ((stack_top + 4) & -16UL) - 4;
 335         frame = (struct sigframe __user *) stack_top - 1;
 336         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 337                 return 1;
 338
 339         restorer = frame->retcode;
 340         if (ka->sa.sa_flags & SA_RESTORER)
 341                 restorer = ka->sa.sa_restorer;
 342
 343         /* Update SP now because the page fault handler refuses to extend
 344          * the stack if the faulting address is too far below the current
 345          * SP, which frame now certainly is.  If there's an error, the original
 346          * value is restored on the way out.
 347          * When writing the sigcontext to the stack, we have to write the
 348          * original value, so that's passed to copy_sc_to_user, which does
 349          * the right thing with it.
 350          */
 351         PT_REGS_SP(regs) = (unsigned long) frame;
 352
 353         err |= __put_user(restorer, &frame->pretcode);
 354         err |= __put_user(sig, &frame->sig);
 355         err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
 356         err |= __put_user(mask->sig[0], &frame->sc.oldmask);
 357         if (_NSIG_WORDS > 1)
 358                 err |= __copy_to_user(&frame->extramask, &mask->sig[1],
 359                                       sizeof(frame->extramask));
 360
 361         /*
 362          * This is popl %eax ; movl $,%eax ; int $0x80
 363          *
 364          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 365          * reasons and because gdb uses it as a signature to notice
 366          * signal handler stack frames.
 367          */
 368         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 369         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 370         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 371
 372         if (err)
 373                 goto err;
 374
 375         PT_REGS_SP(regs) = (unsigned long) frame;
 376         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 377         PT_REGS_EAX(regs) = (unsigned long) sig;
 378         PT_REGS_EDX(regs) = (unsigned long) 0;
 379         PT_REGS_ECX(regs) = (unsigned long) 0;
 380
 381         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 382                 ptrace_notify(SIGTRAP);
 383         return 0;
 384
 385 err:
 386         PT_REGS_SP(regs) = save_sp;
 387         return err;
 388 }
 389
 390 int setup_signal_stack_si(unsigned long stack_top, int sig,
 391                           struct k_sigaction *ka, struct pt_regs *regs,
 392                           siginfo_t *info, sigset_t *mask)
 393 {
 394         struct rt_sigframe __user *frame;
 395         void __user *restorer;
 396         unsigned long save_sp = PT_REGS_SP(regs);
 397         int err = 0;
 398
 399         stack_top &= -8UL;
 400         frame = (struct rt_sigframe __user *) stack_top - 1;
 401         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 402                 return 1;
 403
 404         restorer = frame->retcode;
 405         if (ka->sa.sa_flags & SA_RESTORER)
 406                 restorer = ka->sa.sa_restorer;
 407
 408         /* See comment above about why this is here */
 409         PT_REGS_SP(regs) = (unsigned long) frame;
 410
 411         err |= __put_user(restorer, &frame->pretcode);
 412         err |= __put_user(sig, &frame->sig);
 413         err |= __put_user(&frame->info, &frame->pinfo);
 414         err |= __put_user(&frame->uc, &frame->puc);
 415         err |= copy_siginfo_to_user(&frame->info, info);
 416         err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
 417                                      save_sp);
 418
 419         /*
 420          * This is movl $,%eax ; int $0x80
 421          *
 422          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 423          * reasons and because gdb uses it as a signature to notice
 424          * signal handler stack frames.
 425          */
 426         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 427         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 428         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 429
 430         if (err)
 431                 goto err;
 432
 433         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 434         PT_REGS_EAX(regs) = (unsigned long) sig;
 435         PT_REGS_EDX(regs) = (unsigned long) &frame->info;
 436         PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
 437
 438         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 439                 ptrace_notify(SIGTRAP);
 440         return 0;
 441
 442 err:
 443         PT_REGS_SP(regs) = save_sp;
 444         return err;
 445 }
 446
 447 long sys_sigreturn(struct pt_regs regs)
 448 {
 449         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 450         struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
 451         sigset_t set;
 452         struct sigcontext __user *sc = &frame->sc;
 453         unsigned long __user *oldmask = &sc->oldmask;
 454         unsigned long __user *extramask = frame->extramask;
 455         int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 456
 457         if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
 458             copy_from_user(&set.sig[1], extramask, sig_size))
 459                 goto segfault;
 460
 461         sigdelsetmask(&set, ~_BLOCKABLE);
 462
 463         spin_lock_irq(&current->sighand->siglock);
 464         current->blocked = set;
 465         recalc_sigpending();
 466         spin_unlock_irq(&current->sighand->siglock);
 467
 468         if (copy_sc_from_user(&current->thread.regs, sc))
 469                 goto segfault;
 470
 471         /* Avoid ERESTART handling */
 472         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 473         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 474
 475  segfault:
 476         force_sig(SIGSEGV, current);
 477         return 0;
 478 }
 479
 480 long sys_rt_sigreturn(struct pt_regs regs)
 481 {
 482         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 483         struct rt_sigframe __user *frame =
 484                 (struct rt_sigframe __user *) (sp - 4);
 485         sigset_t set;
 486         struct ucontext __user *uc = &frame->uc;
 487         int sig_size = _NSIG_WORDS * sizeof(unsigned long);
 488
 489         if (copy_from_user(&set, &uc->uc_sigmask, sig_size))
 490                 goto segfault;
 491
 492         sigdelsetmask(&set, ~_BLOCKABLE);
 493
 494         spin_lock_irq(&current->sighand->siglock);
 495         current->blocked = set;
 496         recalc_sigpending();
 497         spin_unlock_irq(&current->sighand->siglock);
 498
 499         if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 500                 goto segfault;
 501
 502         /* Avoid ERESTART handling */
 503         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 504         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 505
 506  segfault:
 507         force_sig(SIGSEGV, current);
 508         return 0;
 509 }