arch/x86/kernel/signal_64.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
   4  *
   5  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   6  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   7  *  2000-2002   x86-64 support by Andi Kleen
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/smp.h>
  13 #include <linux/kernel.h>
  14 #include <linux/signal.h>
  15 #include <linux/errno.h>
  16 #include <linux/wait.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/tracehook.h>
  19 #include <linux/unistd.h>
  20 #include <linux/stddef.h>
  21 #include <linux/personality.h>
  22 #include <linux/uaccess.h>
  23
  24 #include <asm/processor.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/i387.h>
  27 #include <asm/vdso.h>
  28
  29 #ifdef CONFIG_X86_64
  30 #include <asm/proto.h>
  31 #include <asm/ia32_unistd.h>
  32 #include <asm/mce.h>
  33 #endif /* CONFIG_X86_64 */
  34
  35 #include <asm/syscall.h>
  36 #include <asm/syscalls.h>
  37
  38 #include "sigframe.h"
  39
  40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  41
  42 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  43                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  44                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  45                          X86_EFLAGS_CF)
  46
  47 #ifdef CONFIG_X86_32
  48 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  49 #else
  50 # define FIX_EFLAGS     __FIX_EFLAGS
  51 #endif
  52
  53 #ifdef CONFIG_X86_32
  54 asmlinkage int sys_sigaltstack(unsigned long bx)
  55 {
  56         /*
  57          * This is needed to make gcc realize it doesn't own the
  58          * "struct pt_regs"
  59          */
  60         struct pt_regs *regs = (struct pt_regs *)&bx;
  61         const stack_t __user *uss = (const stack_t __user *)bx;
  62         stack_t __user *uoss = (stack_t __user *)regs->cx;
  63
  64         return do_sigaltstack(uss, uoss, regs->sp);
  65 }
  66 #else /* !CONFIG_X86_32 */
  67 asmlinkage long
  68 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  69                 struct pt_regs *regs)
  70 {
  71         return do_sigaltstack(uss, uoss, regs->sp);
  72 }
  73 #endif /* CONFIG_X86_32 */
  74
  75 #define COPY(x)                 {               \
  76         err |= __get_user(regs->x, &sc->x);     \
  77 }
  78
  79 #define COPY_SEG_CPL3(seg)      {                       \
  80                 unsigned short tmp;                     \
  81                 err |= __get_user(tmp, &sc->seg);       \
  82                 regs->seg = tmp | 3;                    \
  83 }
  84
  85 /*
  86  * Do a signal return; undo the signal stack.
  87  */
  88 static int
  89 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
  90                    unsigned long *pax)
  91 {
  92         void __user *buf;
  93         unsigned int tmpflags;
  94         unsigned int err = 0;
  95
  96         /* Always make any pending restarted system calls return -EINTR */
  97         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  98
  99 #ifdef CONFIG_X86_32
 100         GET_SEG(gs);
 101         COPY_SEG(fs);
 102         COPY_SEG(es);
 103         COPY_SEG(ds);
 104 #endif /* CONFIG_X86_32 */
 105
 106         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 107         COPY(dx); COPY(cx); COPY(ip);
 108
 109 #ifdef CONFIG_X86_64
 110         COPY(r8);
 111         COPY(r9);
 112         COPY(r10);
 113         COPY(r11);
 114         COPY(r12);
 115         COPY(r13);
 116         COPY(r14);
 117         COPY(r15);
 118 #endif /* CONFIG_X86_64 */
 119
 120 #ifdef CONFIG_X86_32
 121         COPY_SEG_CPL3(cs);
 122         COPY_SEG_CPL3(ss);
 123 #else /* !CONFIG_X86_32 */
 124         /* Kernel saves and restores only the CS segment register on signals,
 125          * which is the bare minimum needed to allow mixed 32/64-bit code.
 126          * App's signal handler can save/restore other segments if needed. */
 127         COPY_SEG_CPL3(cs);
 128 #endif /* CONFIG_X86_32 */
 129
 130         err |= __get_user(tmpflags, &sc->flags);
 131         regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 132         regs->orig_ax = -1;             /* disable syscall checks */
 133
 134         err |= __get_user(buf, &sc->fpstate);
 135         err |= restore_i387_xstate(buf);
 136
 137         err |= __get_user(*pax, &sc->ax);
 138         return err;
 139 }
 140
 141 static long do_rt_sigreturn(struct pt_regs *regs)
 142 {
 143         struct rt_sigframe __user *frame;
 144         unsigned long ax;
 145         sigset_t set;
 146
 147         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 148         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 149                 goto badframe;
 150         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 151                 goto badframe;
 152
 153         sigdelsetmask(&set, ~_BLOCKABLE);
 154         spin_lock_irq(&current->sighand->siglock);
 155         current->blocked = set;
 156         recalc_sigpending();
 157         spin_unlock_irq(&current->sighand->siglock);
 158
 159         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 160                 goto badframe;
 161
 162         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 163                 goto badframe;
 164
 165         return ax;
 166
 167 badframe:
 168         signal_fault(regs, frame, "rt_sigreturn");
 169         return 0;
 170 }
 171
 172 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 173 {
 174         return do_rt_sigreturn(regs);
 175 }
 176
 177 /*
 178  * Set up a signal frame.
 179  */
 180 static int
 181 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 182                  struct pt_regs *regs, unsigned long mask)
 183 {
 184         int err = 0;
 185
 186 #ifdef CONFIG_X86_32
 187         {
 188                 unsigned int tmp;
 189
 190                 savesegment(gs, tmp);
 191                 err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
 192         }
 193         err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
 194         err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
 195         err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
 196 #endif /* CONFIG_X86_32 */
 197
 198         err |= __put_user(regs->di, &sc->di);
 199         err |= __put_user(regs->si, &sc->si);
 200         err |= __put_user(regs->bp, &sc->bp);
 201         err |= __put_user(regs->sp, &sc->sp);
 202         err |= __put_user(regs->bx, &sc->bx);
 203         err |= __put_user(regs->dx, &sc->dx);
 204         err |= __put_user(regs->cx, &sc->cx);
 205         err |= __put_user(regs->ax, &sc->ax);
 206 #ifdef CONFIG_X86_64
 207         err |= __put_user(regs->r8, &sc->r8);
 208         err |= __put_user(regs->r9, &sc->r9);
 209         err |= __put_user(regs->r10, &sc->r10);
 210         err |= __put_user(regs->r11, &sc->r11);
 211         err |= __put_user(regs->r12, &sc->r12);
 212         err |= __put_user(regs->r13, &sc->r13);
 213         err |= __put_user(regs->r14, &sc->r14);
 214         err |= __put_user(regs->r15, &sc->r15);
 215 #endif /* CONFIG_X86_64 */
 216
 217         err |= __put_user(current->thread.trap_no, &sc->trapno);
 218         err |= __put_user(current->thread.error_code, &sc->err);
 219         err |= __put_user(regs->ip, &sc->ip);
 220 #ifdef CONFIG_X86_32
 221         err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
 222         err |= __put_user(regs->flags, &sc->flags);
 223         err |= __put_user(regs->sp, &sc->sp_at_signal);
 224         err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
 225 #else /* !CONFIG_X86_32 */
 226         err |= __put_user(regs->flags, &sc->flags);
 227         err |= __put_user(regs->cs, &sc->cs);
 228         err |= __put_user(0, &sc->gs);
 229         err |= __put_user(0, &sc->fs);
 230 #endif /* CONFIG_X86_32 */
 231
 232         err |= __put_user(fpstate, &sc->fpstate);
 233
 234         /* non-iBCS2 extensions.. */
 235         err |= __put_user(mask, &sc->oldmask);
 236         err |= __put_user(current->thread.cr2, &sc->cr2);
 237
 238         return err;
 239 }
 240
 241 /*
 242  * Determine which stack to use..
 243  */
 244
 245 static void __user *
 246 get_stack(struct k_sigaction *ka, unsigned long sp, unsigned long size)
 247 {
 248         /* Default to using normal stack - redzone*/
 249         sp -= 128;
 250
 251         /* This is the X/Open sanctioned signal stack switching.  */
 252         if (ka->sa.sa_flags & SA_ONSTACK) {
 253                 if (sas_ss_flags(sp) == 0)
 254                         sp = current->sas_ss_sp + current->sas_ss_size;
 255         }
 256
 257         return (void __user *)round_down(sp - size, 64);
 258 }
 259
 260 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 261                             sigset_t *set, struct pt_regs *regs)
 262 {
 263         struct rt_sigframe __user *frame;
 264         void __user *fp = NULL;
 265         int err = 0;
 266         struct task_struct *me = current;
 267
 268         if (used_math()) {
 269                 fp = get_stack(ka, regs->sp, sig_xstate_size);
 270                 frame = (void __user *)round_down(
 271                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 272
 273                 if (save_i387_xstate(fp) < 0)
 274                         return -EFAULT;
 275         } else
 276                 frame = get_stack(ka, regs->sp, sizeof(struct rt_sigframe)) - 8;
 277
 278         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 279                 return -EFAULT;
 280
 281         if (ka->sa.sa_flags & SA_SIGINFO) {
 282                 if (copy_siginfo_to_user(&frame->info, info))
 283                         return -EFAULT;
 284         }
 285
 286         /* Create the ucontext.  */
 287         if (cpu_has_xsave)
 288                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 289         else
 290                 err |= __put_user(0, &frame->uc.uc_flags);
 291         err |= __put_user(0, &frame->uc.uc_link);
 292         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 293         err |= __put_user(sas_ss_flags(regs->sp),
 294                           &frame->uc.uc_stack.ss_flags);
 295         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 296         err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 297         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 298
 299         /* Set up to return from userspace.  If provided, use a stub
 300            already in userspace.  */
 301         /* x86-64 should always use SA_RESTORER. */
 302         if (ka->sa.sa_flags & SA_RESTORER) {
 303                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 304         } else {
 305                 /* could use a vstub here */
 306                 return -EFAULT;
 307         }
 308
 309         if (err)
 310                 return -EFAULT;
 311
 312         /* Set up registers for signal handler */
 313         regs->di = sig;
 314         /* In case the signal handler was declared without prototypes */
 315         regs->ax = 0;
 316
 317         /* This also works for non SA_SIGINFO handlers because they expect the
 318            next argument after the signal number on the stack. */
 319         regs->si = (unsigned long)&frame->info;
 320         regs->dx = (unsigned long)&frame->uc;
 321         regs->ip = (unsigned long) ka->sa.sa_handler;
 322
 323         regs->sp = (unsigned long)frame;
 324
 325         /* Set up the CS register to run signal handlers in 64-bit mode,
 326            even if the handler happens to be interrupting 32-bit code. */
 327         regs->cs = __USER_CS;
 328
 329         return 0;
 330 }
 331
 332 /*
 333  * OK, we're invoking a handler
 334  */
 335 static int signr_convert(int sig)
 336 {
 337 #ifdef CONFIG_X86_32
 338         struct thread_info *info = current_thread_info();
 339
 340         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 341                 return info->exec_domain->signal_invmap[sig];
 342 #endif /* CONFIG_X86_32 */
 343         return sig;
 344 }
 345
 346 #ifdef CONFIG_X86_32
 347
 348 #define is_ia32 1
 349 #define ia32_setup_frame        __setup_frame
 350 #define ia32_setup_rt_frame     __setup_rt_frame
 351
 352 #else /* !CONFIG_X86_32 */
 353
 354 #ifdef CONFIG_IA32_EMULATION
 355 #define is_ia32 test_thread_flag(TIF_IA32)
 356 #else /* !CONFIG_IA32_EMULATION */
 357 #define is_ia32 0
 358 #endif /* CONFIG_IA32_EMULATION */
 359
 360 #endif /* CONFIG_X86_32 */
 361
 362 static int
 363 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 364                sigset_t *set, struct pt_regs *regs)
 365 {
 366         int usig = signr_convert(sig);
 367         int ret;
 368
 369         /* Set up the stack frame */
 370         if (is_ia32) {
 371                 if (ka->sa.sa_flags & SA_SIGINFO)
 372                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 373                 else
 374                         ret = ia32_setup_frame(usig, ka, set, regs);
 375         } else
 376                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 377
 378         if (ret) {
 379                 force_sigsegv(sig, current);
 380                 return -EFAULT;
 381         }
 382
 383         return ret;
 384 }
 385
 386 static int
 387 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 388               sigset_t *oldset, struct pt_regs *regs)
 389 {
 390         int ret;
 391
 392         /* Are we from a system call? */
 393         if (syscall_get_nr(current, regs) >= 0) {
 394                 /* If so, check system call restarting.. */
 395                 switch (syscall_get_error(current, regs)) {
 396                 case -ERESTART_RESTARTBLOCK:
 397                 case -ERESTARTNOHAND:
 398                         regs->ax = -EINTR;
 399                         break;
 400
 401                 case -ERESTARTSYS:
 402                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 403                                 regs->ax = -EINTR;
 404                                 break;
 405                         }
 406                 /* fallthrough */
 407                 case -ERESTARTNOINTR:
 408                         regs->ax = regs->orig_ax;
 409                         regs->ip -= 2;
 410                         break;
 411                 }
 412         }
 413
 414         /*
 415          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 416          * flag so that register information in the sigcontext is correct.
 417          */
 418         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 419             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 420                 regs->flags &= ~X86_EFLAGS_TF;
 421
 422         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 423
 424         if (ret)
 425                 return ret;
 426
 427 #ifdef CONFIG_X86_64
 428         /*
 429          * This has nothing to do with segment registers,
 430          * despite the name.  This magic affects uaccess.h
 431          * macros' behavior.  Reset it to the normal setting.
 432          */
 433         set_fs(USER_DS);
 434 #endif
 435
 436         /*
 437          * Clear the direction flag as per the ABI for function entry.
 438          */
 439         regs->flags &= ~X86_EFLAGS_DF;
 440
 441         /*
 442          * Clear TF when entering the signal handler, but
 443          * notify any tracer that was single-stepping it.
 444          * The tracer may want to single-step inside the
 445          * handler too.
 446          */
 447         regs->flags &= ~X86_EFLAGS_TF;
 448
 449         spin_lock_irq(&current->sighand->siglock);
 450         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 451         if (!(ka->sa.sa_flags & SA_NODEFER))
 452                 sigaddset(&current->blocked, sig);
 453         recalc_sigpending();
 454         spin_unlock_irq(&current->sighand->siglock);
 455
 456         tracehook_signal_handler(sig, info, ka, regs,
 457                                  test_thread_flag(TIF_SINGLESTEP));
 458
 459         return 0;
 460 }
 461
 462 #ifdef CONFIG_X86_32
 463 #define NR_restart_syscall      __NR_restart_syscall
 464 #else /* !CONFIG_X86_32 */
 465 #define NR_restart_syscall      \
 466         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 467 #endif /* CONFIG_X86_32 */
 468
 469 /*
 470  * Note that 'init' is a special process: it doesn't get signals it doesn't
 471  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 472  * mistake.
 473  */
 474 static void do_signal(struct pt_regs *regs)
 475 {
 476         struct k_sigaction ka;
 477         siginfo_t info;
 478         int signr;
 479         sigset_t *oldset;
 480
 481         /*
 482          * We want the common case to go fast, which is why we may in certain
 483          * cases get here from kernel mode. Just return without doing anything
 484          * if so.
 485          * X86_32: vm86 regs switched out by assembly code before reaching
 486          * here, so testing against kernel CS suffices.
 487          */
 488         if (!user_mode(regs))
 489                 return;
 490
 491         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 492                 oldset = &current->saved_sigmask;
 493         else
 494                 oldset = &current->blocked;
 495
 496         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 497         if (signr > 0) {
 498                 /*
 499                  * Re-enable any watchpoints before delivering the
 500                  * signal to user space. The processor register will
 501                  * have been cleared if the watchpoint triggered
 502                  * inside the kernel.
 503                  */
 504                 if (current->thread.debugreg7)
 505                         set_debugreg(current->thread.debugreg7, 7);
 506
 507                 /* Whee! Actually deliver the signal.  */
 508                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 509                         /*
 510                          * A signal was successfully delivered; the saved
 511                          * sigmask will have been stored in the signal frame,
 512                          * and will be restored by sigreturn, so we can simply
 513                          * clear the TS_RESTORE_SIGMASK flag.
 514                          */
 515                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 516                 }
 517                 return;
 518         }
 519
 520         /* Did we come from a system call? */
 521         if (syscall_get_nr(current, regs) >= 0) {
 522                 /* Restart the system call - no handlers present */
 523                 switch (syscall_get_error(current, regs)) {
 524                 case -ERESTARTNOHAND:
 525                 case -ERESTARTSYS:
 526                 case -ERESTARTNOINTR:
 527                         regs->ax = regs->orig_ax;
 528                         regs->ip -= 2;
 529                         break;
 530
 531                 case -ERESTART_RESTARTBLOCK:
 532                         regs->ax = NR_restart_syscall;
 533                         regs->ip -= 2;
 534                         break;
 535                 }
 536         }
 537
 538         /*
 539          * If there's no signal to deliver, we just put the saved sigmask
 540          * back.
 541          */
 542         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 543                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 544                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 545         }
 546 }
 547
 548 /*
 549  * notification of userspace execution resumption
 550  * - triggered by the TIF_WORK_MASK flags
 551  */
 552 void
 553 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 554 {
 555 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 556         /* notify userspace of pending MCEs */
 557         if (thread_info_flags & _TIF_MCE_NOTIFY)
 558                 mce_notify_user();
 559 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 560
 561         /* deal with pending signal delivery */
 562         if (thread_info_flags & _TIF_SIGPENDING)
 563                 do_signal(regs);
 564
 565         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 566                 clear_thread_flag(TIF_NOTIFY_RESUME);
 567                 tracehook_notify_resume(regs);
 568         }
 569
 570 #ifdef CONFIG_X86_32
 571         clear_thread_flag(TIF_IRET);
 572 #endif /* CONFIG_X86_32 */
 573 }
 574
 575 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 576 {
 577         struct task_struct *me = current;
 578
 579         if (show_unhandled_signals && printk_ratelimit()) {
 580                 printk(KERN_INFO
 581                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 582                        me->comm, me->pid, where, frame,
 583                        regs->ip, regs->sp, regs->orig_ax);
 584                 print_vma_addr(" in ", regs->ip);
 585                 printk(KERN_CONT "\n");
 586         }
 587
 588         force_sig(SIGSEGV, me);
 589 }