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_STRICT(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_STRICT(cs);
 102         COPY_SEG_STRICT(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_STRICT(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
 161 static inline int
 162 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 163                 unsigned long mask, struct task_struct *me)
 164 {
 165         int err = 0;
 166
 167         err |= __put_user(regs->cs, &sc->cs);
 168         err |= __put_user(0, &sc->gs);
 169         err |= __put_user(0, &sc->fs);
 170
 171         err |= __put_user(regs->di, &sc->di);
 172         err |= __put_user(regs->si, &sc->si);
 173         err |= __put_user(regs->bp, &sc->bp);
 174         err |= __put_user(regs->sp, &sc->sp);
 175         err |= __put_user(regs->bx, &sc->bx);
 176         err |= __put_user(regs->dx, &sc->dx);
 177         err |= __put_user(regs->cx, &sc->cx);
 178         err |= __put_user(regs->ax, &sc->ax);
 179         err |= __put_user(regs->r8, &sc->r8);
 180         err |= __put_user(regs->r9, &sc->r9);
 181         err |= __put_user(regs->r10, &sc->r10);
 182         err |= __put_user(regs->r11, &sc->r11);
 183         err |= __put_user(regs->r12, &sc->r12);
 184         err |= __put_user(regs->r13, &sc->r13);
 185         err |= __put_user(regs->r14, &sc->r14);
 186         err |= __put_user(regs->r15, &sc->r15);
 187         err |= __put_user(me->thread.trap_no, &sc->trapno);
 188         err |= __put_user(me->thread.error_code, &sc->err);
 189         err |= __put_user(regs->ip, &sc->ip);
 190         err |= __put_user(regs->flags, &sc->flags);
 191         err |= __put_user(mask, &sc->oldmask);
 192         err |= __put_user(me->thread.cr2, &sc->cr2);
 193
 194         return err;
 195 }
 196
 197 /*
 198  * Determine which stack to use..
 199  */
 200
 201 static void __user *
 202 get_stack(struct k_sigaction *ka, unsigned long sp, unsigned long size)
 203 {
 204         /* Default to using normal stack - redzone*/
 205         sp -= 128;
 206
 207         /* This is the X/Open sanctioned signal stack switching.  */
 208         if (ka->sa.sa_flags & SA_ONSTACK) {
 209                 if (sas_ss_flags(sp) == 0)
 210                         sp = current->sas_ss_sp + current->sas_ss_size;
 211         }
 212
 213         return (void __user *)round_down(sp - size, 64);
 214 }
 215
 216 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 217                             sigset_t *set, struct pt_regs *regs)
 218 {
 219         struct rt_sigframe __user *frame;
 220         void __user *fp = NULL;
 221         int err = 0;
 222         struct task_struct *me = current;
 223
 224         if (used_math()) {
 225                 fp = get_stack(ka, regs->sp, sig_xstate_size);
 226                 frame = (void __user *)round_down(
 227                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 228
 229                 if (save_i387_xstate(fp) < 0)
 230                         return -EFAULT;
 231         } else
 232                 frame = get_stack(ka, regs->sp, sizeof(struct rt_sigframe)) - 8;
 233
 234         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 235                 return -EFAULT;
 236
 237         if (ka->sa.sa_flags & SA_SIGINFO) {
 238                 if (copy_siginfo_to_user(&frame->info, info))
 239                         return -EFAULT;
 240         }
 241
 242         /* Create the ucontext.  */
 243         if (cpu_has_xsave)
 244                 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
 245         else
 246                 err |= __put_user(0, &frame->uc.uc_flags);
 247         err |= __put_user(0, &frame->uc.uc_link);
 248         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 249         err |= __put_user(sas_ss_flags(regs->sp),
 250                           &frame->uc.uc_stack.ss_flags);
 251         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 252         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
 253         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
 254         if (sizeof(*set) == 16) {
 255                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 256                 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 257         } else
 258                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 259
 260         /* Set up to return from userspace.  If provided, use a stub
 261            already in userspace.  */
 262         /* x86-64 should always use SA_RESTORER. */
 263         if (ka->sa.sa_flags & SA_RESTORER) {
 264                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 265         } else {
 266                 /* could use a vstub here */
 267                 return -EFAULT;
 268         }
 269
 270         if (err)
 271                 return -EFAULT;
 272
 273         /* Set up registers for signal handler */
 274         regs->di = sig;
 275         /* In case the signal handler was declared without prototypes */
 276         regs->ax = 0;
 277
 278         /* This also works for non SA_SIGINFO handlers because they expect the
 279            next argument after the signal number on the stack. */
 280         regs->si = (unsigned long)&frame->info;
 281         regs->dx = (unsigned long)&frame->uc;
 282         regs->ip = (unsigned long) ka->sa.sa_handler;
 283
 284         regs->sp = (unsigned long)frame;
 285
 286         /* Set up the CS register to run signal handlers in 64-bit mode,
 287            even if the handler happens to be interrupting 32-bit code. */
 288         regs->cs = __USER_CS;
 289
 290         return 0;
 291 }
 292
 293 /*
 294  * OK, we're invoking a handler
 295  */
 296 static int signr_convert(int sig)
 297 {
 298 #ifdef CONFIG_X86_32
 299         struct thread_info *info = current_thread_info();
 300
 301         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 302                 return info->exec_domain->signal_invmap[sig];
 303 #endif /* CONFIG_X86_32 */
 304         return sig;
 305 }
 306
 307 #ifdef CONFIG_X86_32
 308
 309 #define is_ia32 1
 310 #define ia32_setup_frame        __setup_frame
 311 #define ia32_setup_rt_frame     __setup_rt_frame
 312
 313 #else /* !CONFIG_X86_32 */
 314
 315 #ifdef CONFIG_IA32_EMULATION
 316 #define is_ia32 test_thread_flag(TIF_IA32)
 317 #else /* !CONFIG_IA32_EMULATION */
 318 #define is_ia32 0
 319 #endif /* CONFIG_IA32_EMULATION */
 320
 321 #endif /* CONFIG_X86_32 */
 322
 323 static int
 324 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 325                sigset_t *set, struct pt_regs *regs)
 326 {
 327         int usig = signr_convert(sig);
 328         int ret;
 329
 330         /* Set up the stack frame */
 331         if (is_ia32) {
 332                 if (ka->sa.sa_flags & SA_SIGINFO)
 333                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 334                 else
 335                         ret = ia32_setup_frame(usig, ka, set, regs);
 336         } else
 337                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 338
 339         if (ret) {
 340                 force_sigsegv(sig, current);
 341                 return -EFAULT;
 342         }
 343
 344         return ret;
 345 }
 346
 347 static int
 348 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 349               sigset_t *oldset, struct pt_regs *regs)
 350 {
 351         int ret;
 352
 353         /* Are we from a system call? */
 354         if (syscall_get_nr(current, regs) >= 0) {
 355                 /* If so, check system call restarting.. */
 356                 switch (syscall_get_error(current, regs)) {
 357                 case -ERESTART_RESTARTBLOCK:
 358                 case -ERESTARTNOHAND:
 359                         regs->ax = -EINTR;
 360                         break;
 361
 362                 case -ERESTARTSYS:
 363                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 364                                 regs->ax = -EINTR;
 365                                 break;
 366                         }
 367                 /* fallthrough */
 368                 case -ERESTARTNOINTR:
 369                         regs->ax = regs->orig_ax;
 370                         regs->ip -= 2;
 371                         break;
 372                 }
 373         }
 374
 375         /*
 376          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 377          * flag so that register information in the sigcontext is correct.
 378          */
 379         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 380             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 381                 regs->flags &= ~X86_EFLAGS_TF;
 382
 383         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 384
 385         if (ret)
 386                 return ret;
 387
 388 #ifdef CONFIG_X86_64
 389         /*
 390          * This has nothing to do with segment registers,
 391          * despite the name.  This magic affects uaccess.h
 392          * macros' behavior.  Reset it to the normal setting.
 393          */
 394         set_fs(USER_DS);
 395 #endif
 396
 397         /*
 398          * Clear the direction flag as per the ABI for function entry.
 399          */
 400         regs->flags &= ~X86_EFLAGS_DF;
 401
 402         /*
 403          * Clear TF when entering the signal handler, but
 404          * notify any tracer that was single-stepping it.
 405          * The tracer may want to single-step inside the
 406          * handler too.
 407          */
 408         regs->flags &= ~X86_EFLAGS_TF;
 409
 410         spin_lock_irq(&current->sighand->siglock);
 411         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 412         if (!(ka->sa.sa_flags & SA_NODEFER))
 413                 sigaddset(&current->blocked, sig);
 414         recalc_sigpending();
 415         spin_unlock_irq(&current->sighand->siglock);
 416
 417         tracehook_signal_handler(sig, info, ka, regs,
 418                                  test_thread_flag(TIF_SINGLESTEP));
 419
 420         return 0;
 421 }
 422
 423 #define NR_restart_syscall      \
 424         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 425 /*
 426  * Note that 'init' is a special process: it doesn't get signals it doesn't
 427  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 428  * mistake.
 429  */
 430 static void do_signal(struct pt_regs *regs)
 431 {
 432         struct k_sigaction ka;
 433         siginfo_t info;
 434         int signr;
 435         sigset_t *oldset;
 436
 437         /*
 438          * We want the common case to go fast, which is why we may in certain
 439          * cases get here from kernel mode. Just return without doing anything
 440          * if so.
 441          * X86_32: vm86 regs switched out by assembly code before reaching
 442          * here, so testing against kernel CS suffices.
 443          */
 444         if (!user_mode(regs))
 445                 return;
 446
 447         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 448                 oldset = &current->saved_sigmask;
 449         else
 450                 oldset = &current->blocked;
 451
 452         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 453         if (signr > 0) {
 454                 /*
 455                  * Re-enable any watchpoints before delivering the
 456                  * signal to user space. The processor register will
 457                  * have been cleared if the watchpoint triggered
 458                  * inside the kernel.
 459                  */
 460                 if (current->thread.debugreg7)
 461                         set_debugreg(current->thread.debugreg7, 7);
 462
 463                 /* Whee! Actually deliver the signal.  */
 464                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 465                         /*
 466                          * A signal was successfully delivered; the saved
 467                          * sigmask will have been stored in the signal frame,
 468                          * and will be restored by sigreturn, so we can simply
 469                          * clear the TS_RESTORE_SIGMASK flag.
 470                          */
 471                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 472                 }
 473                 return;
 474         }
 475
 476         /* Did we come from a system call? */
 477         if (syscall_get_nr(current, regs) >= 0) {
 478                 /* Restart the system call - no handlers present */
 479                 switch (syscall_get_error(current, regs)) {
 480                 case -ERESTARTNOHAND:
 481                 case -ERESTARTSYS:
 482                 case -ERESTARTNOINTR:
 483                         regs->ax = regs->orig_ax;
 484                         regs->ip -= 2;
 485                         break;
 486
 487                 case -ERESTART_RESTARTBLOCK:
 488                         regs->ax = NR_restart_syscall;
 489                         regs->ip -= 2;
 490                         break;
 491                 }
 492         }
 493
 494         /*
 495          * If there's no signal to deliver, we just put the saved sigmask
 496          * back.
 497          */
 498         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 499                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 500                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 501         }
 502 }
 503
 504 /*
 505  * notification of userspace execution resumption
 506  * - triggered by the TIF_WORK_MASK flags
 507  */
 508 void
 509 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 510 {
 511 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 512         /* notify userspace of pending MCEs */
 513         if (thread_info_flags & _TIF_MCE_NOTIFY)
 514                 mce_notify_user();
 515 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 516
 517         /* deal with pending signal delivery */
 518         if (thread_info_flags & _TIF_SIGPENDING)
 519                 do_signal(regs);
 520
 521         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 522                 clear_thread_flag(TIF_NOTIFY_RESUME);
 523                 tracehook_notify_resume(regs);
 524         }
 525
 526 #ifdef CONFIG_X86_32
 527         clear_thread_flag(TIF_IRET);
 528 #endif /* CONFIG_X86_32 */
 529 }
 530
 531 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 532 {
 533         struct task_struct *me = current;
 534
 535         if (show_unhandled_signals && printk_ratelimit()) {
 536                 printk(KERN_INFO
 537                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 538                        me->comm, me->pid, where, frame,
 539                        regs->ip, regs->sp, regs->orig_ax);
 540                 print_vma_addr(" in ", regs->ip);
 541                 printk(KERN_CONT "\n");
 542         }
 543
 544         force_sig(SIGSEGV, me);
 545 }