arch/x86/um/signal_32.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 /*
  14  * FPU tag word conversions.
  15  */
  16
  17 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
  18 {
  19         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
  20
  21         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
  22         tmp = ~twd;
  23         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
  24         /* and move the valid bits to the lower byte. */
  25         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
  26         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
  27         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
  28         return tmp;
  29 }
  30
  31 static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
  32 {
  33         struct _fpxreg *st = NULL;
  34         unsigned long twd = (unsigned long) fxsave->twd;
  35         unsigned long tag;
  36         unsigned long ret = 0xffff0000;
  37         int i;
  38
  39 #define FPREG_ADDR(f, n)        ((char *)&(f)->st_space + (n) * 16)
  40
  41         for (i = 0; i < 8; i++) {
  42                 if (twd & 0x1) {
  43                         st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);
  44
  45                         switch (st->exponent & 0x7fff) {
  46                         case 0x7fff:
  47                                 tag = 2;                /* Special */
  48                                 break;
  49                         case 0x0000:
  50                                 if ( !st->significand[0] &&
  51                                      !st->significand[1] &&
  52                                      !st->significand[2] &&
  53                                      !st->significand[3] ) {
  54                                         tag = 1;        /* Zero */
  55                                 } else {
  56                                         tag = 2;        /* Special */
  57                                 }
  58                                 break;
  59                         default:
  60                                 if (st->significand[3] & 0x8000) {
  61                                         tag = 0;        /* Valid */
  62                                 } else {
  63                                         tag = 2;        /* Special */
  64                                 }
  65                                 break;
  66                         }
  67                 } else {
  68                         tag = 3;                        /* Empty */
  69                 }
  70                 ret |= (tag << (2 * i));
  71                 twd = twd >> 1;
  72         }
  73         return ret;
  74 }
  75
  76 static int convert_fxsr_to_user(struct _fpstate __user *buf,
  77                                 struct user_fxsr_struct *fxsave)
  78 {
  79         unsigned long env[7];
  80         struct _fpreg __user *to;
  81         struct _fpxreg *from;
  82         int i;
  83
  84         env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
  85         env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
  86         env[2] = twd_fxsr_to_i387(fxsave);
  87         env[3] = fxsave->fip;
  88         env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
  89         env[5] = fxsave->foo;
  90         env[6] = fxsave->fos;
  91
  92         if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
  93                 return 1;
  94
  95         to = &buf->_st[0];
  96         from = (struct _fpxreg *) &fxsave->st_space[0];
  97         for (i = 0; i < 8; i++, to++, from++) {
  98                 unsigned long __user *t = (unsigned long __user *)to;
  99                 unsigned long *f = (unsigned long *)from;
 100
 101                 if (__put_user(*f, t) ||
 102                                 __put_user(*(f + 1), t + 1) ||
 103                                 __put_user(from->exponent, &to->exponent))
 104                         return 1;
 105         }
 106         return 0;
 107 }
 108
 109 static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
 110                                   struct _fpstate __user *buf)
 111 {
 112         unsigned long env[7];
 113         struct _fpxreg *to;
 114         struct _fpreg __user *from;
 115         int i;
 116
 117         if (copy_from_user( env, buf, 7 * sizeof(long)))
 118                 return 1;
 119
 120         fxsave->cwd = (unsigned short)(env[0] & 0xffff);
 121         fxsave->swd = (unsigned short)(env[1] & 0xffff);
 122         fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
 123         fxsave->fip = env[3];
 124         fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
 125         fxsave->fcs = (env[4] & 0xffff);
 126         fxsave->foo = env[5];
 127         fxsave->fos = env[6];
 128
 129         to = (struct _fpxreg *) &fxsave->st_space[0];
 130         from = &buf->_st[0];
 131         for (i = 0; i < 8; i++, to++, from++) {
 132                 unsigned long *t = (unsigned long *)to;
 133                 unsigned long __user *f = (unsigned long __user *)from;
 134
 135                 if (__get_user(*t, f) ||
 136                     __get_user(*(t + 1), f + 1) ||
 137                     __get_user(to->exponent, &from->exponent))
 138                         return 1;
 139         }
 140         return 0;
 141 }
 142
 143 extern int have_fpx_regs;
 144
 145 static int copy_sc_from_user(struct pt_regs *regs,
 146                              struct sigcontext __user *from)
 147 {
 148         struct sigcontext sc;
 149         int err, pid;
 150
 151         err = copy_from_user(&sc, from, sizeof(sc));
 152         if (err)
 153                 return err;
 154
 155         pid = userspace_pid[current_thread_info()->cpu];
 156
 157 #define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname
 158
 159         GETREG(GS, gs);
 160         GETREG(FS, fs);
 161         GETREG(ES, es);
 162         GETREG(DS, ds);
 163         GETREG(DI, di);
 164         GETREG(SI, si);
 165         GETREG(BP, bp);
 166         GETREG(SP, sp);
 167         GETREG(BX, bx);
 168         GETREG(DX, dx);
 169         GETREG(CX, cx);
 170         GETREG(AX, ax);
 171         GETREG(IP, ip);
 172         GETREG(CS, cs);
 173         GETREG(EFLAGS, flags);
 174         GETREG(SS, ss);
 175
 176 #undef GETREG
 177         if (have_fpx_regs) {
 178                 struct user_fxsr_struct fpx;
 179
 180                 err = copy_from_user(&fpx,
 181                         &((struct _fpstate __user *)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(pid, (unsigned long *) &fpx);
 191                 if (err < 0) {
 192                         printk(KERN_ERR "copy_sc_from_user - "
 193                                "restore_fpx_registers failed, errno = %d\n",
 194                                -err);
 195                         return 1;
 196                 }
 197         } else {
 198                 struct user_i387_struct fp;
 199
 200                 err = copy_from_user(&fp, sc.fpstate,
 201                                      sizeof(struct user_i387_struct));
 202                 if (err)
 203                         return 1;
 204
 205                 err = restore_fp_registers(pid, (unsigned long *) &fp);
 206                 if (err < 0) {
 207                         printk(KERN_ERR "copy_sc_from_user - "
 208                                "restore_fp_registers failed, errno = %d\n",
 209                                -err);
 210                         return 1;
 211                 }
 212         }
 213
 214         return 0;
 215 }
 216
 217 static int copy_sc_to_user(struct sigcontext __user *to,
 218                            struct _fpstate __user *to_fp, struct pt_regs *regs,
 219                            unsigned long sp)
 220 {
 221         struct sigcontext sc;
 222         struct faultinfo * fi = &current->thread.arch.faultinfo;
 223         int err, pid;
 224         memset(&sc, 0, sizeof(struct sigcontext));
 225
 226         sc.gs = REGS_GS(regs->regs.gp);
 227         sc.fs = REGS_FS(regs->regs.gp);
 228         sc.es = REGS_ES(regs->regs.gp);
 229         sc.ds = REGS_DS(regs->regs.gp);
 230         sc.di = REGS_EDI(regs->regs.gp);
 231         sc.si = REGS_ESI(regs->regs.gp);
 232         sc.bp = REGS_EBP(regs->regs.gp);
 233         sc.sp = sp;
 234         sc.bx = REGS_EBX(regs->regs.gp);
 235         sc.dx = REGS_EDX(regs->regs.gp);
 236         sc.cx = REGS_ECX(regs->regs.gp);
 237         sc.ax = REGS_EAX(regs->regs.gp);
 238         sc.ip = REGS_IP(regs->regs.gp);
 239         sc.cs = REGS_CS(regs->regs.gp);
 240         sc.flags = REGS_EFLAGS(regs->regs.gp);
 241         sc.sp_at_signal = regs->regs.gp[UESP];
 242         sc.ss = regs->regs.gp[SS];
 243         sc.cr2 = fi->cr2;
 244         sc.err = fi->error_code;
 245         sc.trapno = fi->trap_no;
 246
 247         to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
 248         sc.fpstate = to_fp;
 249
 250         pid = userspace_pid[current_thread_info()->cpu];
 251         if (have_fpx_regs) {
 252                 struct user_fxsr_struct fpx;
 253
 254                 err = save_fpx_registers(pid, (unsigned long *) &fpx);
 255                 if (err < 0){
 256                         printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
 257                                "failed, errno = %d\n", err);
 258                         return 1;
 259                 }
 260
 261                 err = convert_fxsr_to_user(to_fp, &fpx);
 262                 if (err)
 263                         return 1;
 264
 265                 err |= __put_user(fpx.swd, &to_fp->status);
 266                 err |= __put_user(X86_FXSR_MAGIC, &to_fp->magic);
 267                 if (err)
 268                         return 1;
 269
 270                 if (copy_to_user(&to_fp->_fxsr_env[0], &fpx,
 271                                  sizeof(struct user_fxsr_struct)))
 272                         return 1;
 273         }
 274         else {
 275                 struct user_i387_struct fp;
 276
 277                 err = save_fp_registers(pid, (unsigned long *) &fp);
 278                 if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
 279                         return 1;
 280         }
 281
 282         return copy_to_user(to, &sc, sizeof(sc));
 283 }
 284
 285 static int copy_ucontext_to_user(struct ucontext __user *uc,
 286                                  struct _fpstate __user *fp, sigset_t *set,
 287                                  unsigned long sp)
 288 {
 289         int err = 0;
 290
 291         err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
 292         err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
 293         err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
 294         err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
 295         err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
 296         return err;
 297 }
 298
 299 struct sigframe
 300 {
 301         char __user *pretcode;
 302         int sig;
 303         struct sigcontext sc;
 304         struct _fpstate fpstate;
 305         unsigned long extramask[_NSIG_WORDS-1];
 306         char retcode[8];
 307 };
 308
 309 struct rt_sigframe
 310 {
 311         char __user *pretcode;
 312         int sig;
 313         struct siginfo __user *pinfo;
 314         void __user *puc;
 315         struct siginfo info;
 316         struct ucontext uc;
 317         struct _fpstate fpstate;
 318         char retcode[8];
 319 };
 320
 321 int setup_signal_stack_sc(unsigned long stack_top, int sig,
 322                           struct k_sigaction *ka, struct pt_regs *regs,
 323                           sigset_t *mask)
 324 {
 325         struct sigframe __user *frame;
 326         void __user *restorer;
 327         unsigned long save_sp = PT_REGS_SP(regs);
 328         int err = 0;
 329
 330         /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
 331         stack_top = ((stack_top + 4) & -16UL) - 4;
 332         frame = (struct sigframe __user *) stack_top - 1;
 333         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 334                 return 1;
 335
 336         restorer = frame->retcode;
 337         if (ka->sa.sa_flags & SA_RESTORER)
 338                 restorer = ka->sa.sa_restorer;
 339
 340         /* Update SP now because the page fault handler refuses to extend
 341          * the stack if the faulting address is too far below the current
 342          * SP, which frame now certainly is.  If there's an error, the original
 343          * value is restored on the way out.
 344          * When writing the sigcontext to the stack, we have to write the
 345          * original value, so that's passed to copy_sc_to_user, which does
 346          * the right thing with it.
 347          */
 348         PT_REGS_SP(regs) = (unsigned long) frame;
 349
 350         err |= __put_user(restorer, &frame->pretcode);
 351         err |= __put_user(sig, &frame->sig);
 352         err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
 353         err |= __put_user(mask->sig[0], &frame->sc.oldmask);
 354         if (_NSIG_WORDS > 1)
 355                 err |= __copy_to_user(&frame->extramask, &mask->sig[1],
 356                                       sizeof(frame->extramask));
 357
 358         /*
 359          * This is popl %eax ; movl $,%eax ; int $0x80
 360          *
 361          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 362          * reasons and because gdb uses it as a signature to notice
 363          * signal handler stack frames.
 364          */
 365         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 366         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 367         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 368
 369         if (err)
 370                 goto err;
 371
 372         PT_REGS_SP(regs) = (unsigned long) frame;
 373         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 374         PT_REGS_EAX(regs) = (unsigned long) sig;
 375         PT_REGS_EDX(regs) = (unsigned long) 0;
 376         PT_REGS_ECX(regs) = (unsigned long) 0;
 377
 378         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 379                 ptrace_notify(SIGTRAP);
 380         return 0;
 381
 382 err:
 383         PT_REGS_SP(regs) = save_sp;
 384         return err;
 385 }
 386
 387 int setup_signal_stack_si(unsigned long stack_top, int sig,
 388                           struct k_sigaction *ka, struct pt_regs *regs,
 389                           siginfo_t *info, sigset_t *mask)
 390 {
 391         struct rt_sigframe __user *frame;
 392         void __user *restorer;
 393         unsigned long save_sp = PT_REGS_SP(regs);
 394         int err = 0;
 395
 396         stack_top &= -8UL;
 397         frame = (struct rt_sigframe __user *) stack_top - 1;
 398         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 399                 return 1;
 400
 401         restorer = frame->retcode;
 402         if (ka->sa.sa_flags & SA_RESTORER)
 403                 restorer = ka->sa.sa_restorer;
 404
 405         /* See comment above about why this is here */
 406         PT_REGS_SP(regs) = (unsigned long) frame;
 407
 408         err |= __put_user(restorer, &frame->pretcode);
 409         err |= __put_user(sig, &frame->sig);
 410         err |= __put_user(&frame->info, &frame->pinfo);
 411         err |= __put_user(&frame->uc, &frame->puc);
 412         err |= copy_siginfo_to_user(&frame->info, info);
 413         err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
 414                                      save_sp);
 415
 416         /*
 417          * This is movl $,%eax ; int $0x80
 418          *
 419          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 420          * reasons and because gdb uses it as a signature to notice
 421          * signal handler stack frames.
 422          */
 423         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 424         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 425         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 426
 427         if (err)
 428                 goto err;
 429
 430         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 431         PT_REGS_EAX(regs) = (unsigned long) sig;
 432         PT_REGS_EDX(regs) = (unsigned long) &frame->info;
 433         PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
 434
 435         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 436                 ptrace_notify(SIGTRAP);
 437         return 0;
 438
 439 err:
 440         PT_REGS_SP(regs) = save_sp;
 441         return err;
 442 }
 443
 444 long sys_sigreturn(struct pt_regs regs)
 445 {
 446         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 447         struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
 448         sigset_t set;
 449         struct sigcontext __user *sc = &frame->sc;
 450         unsigned long __user *oldmask = &sc->oldmask;
 451         unsigned long __user *extramask = frame->extramask;
 452         int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 453
 454         if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
 455             copy_from_user(&set.sig[1], extramask, sig_size))
 456                 goto segfault;
 457
 458         sigdelsetmask(&set, ~_BLOCKABLE);
 459         set_current_blocked(&set);
 460
 461         if (copy_sc_from_user(&current->thread.regs, sc))
 462                 goto segfault;
 463
 464         /* Avoid ERESTART handling */
 465         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 466         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 467
 468  segfault:
 469         force_sig(SIGSEGV, current);
 470         return 0;
 471 }
 472
 473 long sys_rt_sigreturn(struct pt_regs regs)
 474 {
 475         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 476         struct rt_sigframe __user *frame =
 477                 (struct rt_sigframe __user *) (sp - 4);
 478         sigset_t set;
 479         struct ucontext __user *uc = &frame->uc;
 480         int sig_size = _NSIG_WORDS * sizeof(unsigned long);
 481
 482         if (copy_from_user(&set, &uc->uc_sigmask, sig_size))
 483                 goto segfault;
 484
 485         sigdelsetmask(&set, ~_BLOCKABLE);
 486         set_current_blocked(&set);
 487
 488         if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 489                 goto segfault;
 490
 491         /* Avoid ERESTART handling */
 492         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 493         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 494
 495  segfault:
 496         force_sig(SIGSEGV, current);
 497         return 0;
 498 }