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