LXR linux/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
  13void 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
  39static 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
  53static 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
  98static 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
 131static 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
 165extern int have_fpx_regs;
 166
 167static int copy_sc_from_user(struct pt_regs *regs,
 168                             struct sigcontext __user *from)
 169{
 170        struct sigcontext sc;
 171        int err, pid;
 172
 173        err = copy_from_user(&sc, from, sizeof(sc));
 174        if (err)
 175                return err;
 176
 177        pid = userspace_pid[current_thread_info()->cpu];
 178        copy_sc(&regs->regs, &sc);
 179        if (have_fpx_regs) {
 180                struct user_fxsr_struct fpx;
 181
 182                err = copy_from_user(&fpx,
 183                        &((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
 184                                     sizeof(struct user_fxsr_struct));
 185                if (err)
 186                        return 1;
 187
 188                err = convert_fxsr_from_user(&fpx, sc.fpstate);
 189                if (err)
 190                        return 1;
 191
 192                err = restore_fpx_registers(pid, (unsigned long *) &fpx);
 193                if (err < 0) {
 194                        printk(KERN_ERR "copy_sc_from_user - "
 195                               "restore_fpx_registers failed, errno = %d\n",
 196                               -err);
 197                        return 1;
 198                }
 199        }
 200        else {
 201                struct user_i387_struct fp;
 202
 203                err = copy_from_user(&fp, sc.fpstate,
 204                                     sizeof(struct user_i387_struct));
 205                if (err)
 206                        return 1;
 207
 208                err = restore_fp_registers(pid, (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
 220static 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, pid;
 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        pid = userspace_pid[current_thread_info()->cpu];
 253        if (have_fpx_regs) {
 254                struct user_fxsr_struct fpx;
 255
 256                err = save_fpx_registers(pid, (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(pid, (unsigned long *) &fp);
 280                if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
 281                        return 1;
 282        }
 283
 284        return copy_to_user(to, &sc, sizeof(sc));
 285}
 286
 287static int copy_ucontext_to_user(struct ucontext __user *uc,
 288                                 struct _fpstate __user *fp, sigset_t *set,
 289                                 unsigned long sp)
 290{
 291        int err = 0;
 292
 293        err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
 294        err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
 295        err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
 296        err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
 297        err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
 298        return err;
 299}
 300
 301struct sigframe
 302{
 303        char __user *pretcode;
 304        int sig;
 305        struct sigcontext sc;
 306        struct _fpstate fpstate;
 307        unsigned long extramask[_NSIG_WORDS-1];
 308        char retcode[8];
 309};
 310
 311struct rt_sigframe
 312{
 313        char __user *pretcode;
 314        int sig;
 315        struct siginfo __user *pinfo;
 316        void __user *puc;
 317        struct siginfo info;
 318        struct ucontext uc;
 319        struct _fpstate fpstate;
 320        char retcode[8];
 321};
 322
 323int setup_signal_stack_sc(unsigned long stack_top, int sig,
 324                          struct k_sigaction *ka, struct pt_regs *regs,
 325                          sigset_t *mask)
 326{
 327        struct sigframe __user *frame;
 328        void __user *restorer;
 329        unsigned long save_sp = PT_REGS_SP(regs);
 330        int err = 0;
 331
 332        /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
 333        stack_top = ((stack_top + 4) & -16UL) - 4;
 334        frame = (struct sigframe __user *) stack_top - 1;
 335        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 336                return 1;
 337
 338        restorer = frame->retcode;
 339        if (ka->sa.sa_flags & SA_RESTORER)
 340                restorer = ka->sa.sa_restorer;
 341
 342        /* Update SP now because the page fault handler refuses to extend
 343         * the stack if the faulting address is too far below the current
 344         * SP, which frame now certainly is.  If there's an error, the original
 345         * value is restored on the way out.
 346         * When writing the sigcontext to the stack, we have to write the
 347         * original value, so that's passed to copy_sc_to_user, which does
 348         * the right thing with it.
 349         */
 350        PT_REGS_SP(regs) = (unsigned long) frame;
 351
 352        err |= __put_user(restorer, &frame->pretcode);
 353        err |= __put_user(sig, &frame->sig);
 354        err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
 355        err |= __put_user(mask->sig[0], &frame->sc.oldmask);
 356        if (_NSIG_WORDS > 1)
 357                err |= __copy_to_user(&frame->extramask, &mask->sig[1],
 358                                      sizeof(frame->extramask));
 359
 360        /*
 361         * This is popl %eax ; movl $,%eax ; int $0x80
 362         *
 363         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 364         * reasons and because gdb uses it as a signature to notice
 365         * signal handler stack frames.
 366         */
 367        err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 368        err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 369        err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 370
 371        if (err)
 372                goto err;
 373
 374        PT_REGS_SP(regs) = (unsigned long) frame;
 375        PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 376        PT_REGS_EAX(regs) = (unsigned long) sig;
 377        PT_REGS_EDX(regs) = (unsigned long) 0;
 378        PT_REGS_ECX(regs) = (unsigned long) 0;
 379
 380        if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 381                ptrace_notify(SIGTRAP);
 382        return 0;
 383
 384err:
 385        PT_REGS_SP(regs) = save_sp;
 386        return err;
 387}
 388
 389int setup_signal_stack_si(unsigned long stack_top, int sig,
 390                          struct k_sigaction *ka, struct pt_regs *regs,
 391                          siginfo_t *info, sigset_t *mask)
 392{
 393        struct rt_sigframe __user *frame;
 394        void __user *restorer;
 395        unsigned long save_sp = PT_REGS_SP(regs);
 396        int err = 0;
 397
 398        stack_top &= -8UL;
 399        frame = (struct rt_sigframe __user *) stack_top - 1;
 400        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 401                return 1;
 402
 403        restorer = frame->retcode;
 404        if (ka->sa.sa_flags & SA_RESTORER)
 405                restorer = ka->sa.sa_restorer;
 406
 407        /* See comment above about why this is here */
 408        PT_REGS_SP(regs) = (unsigned long) frame;
 409
 410        err |= __put_user(restorer, &frame->pretcode);
 411        err |= __put_user(sig, &frame->sig);
 412        err |= __put_user(&frame->info, &frame->pinfo);
 413        err |= __put_user(&frame->uc, &frame->puc);
 414        err |= copy_siginfo_to_user(&frame->info, info);
 415        err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
 416                                     save_sp);
 417
 418        /*
 419         * This is movl $,%eax ; int $0x80
 420         *
 421         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 422         * reasons and because gdb uses it as a signature to notice
 423         * signal handler stack frames.
 424         */
 425        err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 426        err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 427        err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 428
 429        if (err)
 430                goto err;
 431
 432        PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 433        PT_REGS_EAX(regs) = (unsigned long) sig;
 434        PT_REGS_EDX(regs) = (unsigned long) &frame->info;
 435        PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
 436
 437        if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 438                ptrace_notify(SIGTRAP);
 439        return 0;
 440
 441err:
 442        PT_REGS_SP(regs) = save_sp;
 443        return err;
 444}
 445
 446long sys_sigreturn(struct pt_regs regs)
 447{
 448        unsigned long sp = PT_REGS_SP(&current->thread.regs);
 449        struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
 450        sigset_t set;
 451        struct sigcontext __user *sc = &frame->sc;
 452        unsigned long __user *oldmask = &sc->oldmask;
 453        unsigned long __user *extramask = frame->extramask;
 454        int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 455
 456        if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
 457            copy_from_user(&set.sig[1], extramask, sig_size))
 458                goto segfault;
 459
 460        sigdelsetmask(&set, ~_BLOCKABLE);
 461
 462        spin_lock_irq(&current->sighand->siglock);
 463        current->blocked = set;
 464        recalc_sigpending();
 465        spin_unlock_irq(&current->sighand->siglock);
 466
 467        if (copy_sc_from_user(&current->thread.regs, sc))
 468                goto segfault;
 469
 470        /* Avoid ERESTART handling */
 471        PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 472        return PT_REGS_SYSCALL_RET(&current->thread.regs);
 473
 474 segfault:
 475        force_sig(SIGSEGV, current);
 476        return 0;
 477}
 478
 479long sys_rt_sigreturn(struct pt_regs regs)
 480{
 481        unsigned long sp = PT_REGS_SP(&current->thread.regs);
 482        struct rt_sigframe __user *frame =
 483                (struct rt_sigframe __user *) (sp - 4);
 484        sigset_t set;
 485        struct ucontext __user *uc = &frame->uc;
 486        int sig_size = _NSIG_WORDS * sizeof(unsigned long);
 487
 488        if (copy_from_user(&set, &uc->uc_sigmask, sig_size))
 489                goto segfault;
 490
 491        sigdelsetmask(&set, ~_BLOCKABLE);
 492
 493        spin_lock_irq(&current->sighand->siglock);
 494        current->blocked = set;
 495        recalc_sigpending();
 496        spin_unlock_irq(&current->sighand->siglock);
 497
 498        if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 499                goto segfault;
 500
 501        /* Avoid ERESTART handling */
 502        PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 503        return PT_REGS_SYSCALL_RET(&current->thread.regs);
 504
 505 segfault:
 506        force_sig(SIGSEGV, current);
 507        return 0;
 508}
 509