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         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 255
 256         /* Set up to return from userspace.  If provided, use a stub
 257            already in userspace.  */
 258         /* x86-64 should always use SA_RESTORER. */
 259         if (ka->sa.sa_flags & SA_RESTORER) {
 260                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 261         } else {
 262                 /* could use a vstub here */
 263                 return -EFAULT;
 264         }
 265
 266         if (err)
 267                 return -EFAULT;
 268
 269         /* Set up registers for signal handler */
 270         regs->di = sig;
 271         /* In case the signal handler was declared without prototypes */
 272         regs->ax = 0;
 273
 274         /* This also works for non SA_SIGINFO handlers because they expect the
 275            next argument after the signal number on the stack. */
 276         regs->si = (unsigned long)&frame->info;
 277         regs->dx = (unsigned long)&frame->uc;
 278         regs->ip = (unsigned long) ka->sa.sa_handler;
 279
 280         regs->sp = (unsigned long)frame;
 281
 282         /* Set up the CS register to run signal handlers in 64-bit mode,
 283            even if the handler happens to be interrupting 32-bit code. */
 284         regs->cs = __USER_CS;
 285
 286         return 0;
 287 }
 288
 289 /*
 290  * OK, we're invoking a handler
 291  */
 292 static int signr_convert(int sig)
 293 {
 294 #ifdef CONFIG_X86_32
 295         struct thread_info *info = current_thread_info();
 296
 297         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 298                 return info->exec_domain->signal_invmap[sig];
 299 #endif /* CONFIG_X86_32 */
 300         return sig;
 301 }
 302
 303 #ifdef CONFIG_X86_32
 304
 305 #define is_ia32 1
 306 #define ia32_setup_frame        __setup_frame
 307 #define ia32_setup_rt_frame     __setup_rt_frame
 308
 309 #else /* !CONFIG_X86_32 */
 310
 311 #ifdef CONFIG_IA32_EMULATION
 312 #define is_ia32 test_thread_flag(TIF_IA32)
 313 #else /* !CONFIG_IA32_EMULATION */
 314 #define is_ia32 0
 315 #endif /* CONFIG_IA32_EMULATION */
 316
 317 #endif /* CONFIG_X86_32 */
 318
 319 static int
 320 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 321                sigset_t *set, struct pt_regs *regs)
 322 {
 323         int usig = signr_convert(sig);
 324         int ret;
 325
 326         /* Set up the stack frame */
 327         if (is_ia32) {
 328                 if (ka->sa.sa_flags & SA_SIGINFO)
 329                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 330                 else
 331                         ret = ia32_setup_frame(usig, ka, set, regs);
 332         } else
 333                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 334
 335         if (ret) {
 336                 force_sigsegv(sig, current);
 337                 return -EFAULT;
 338         }
 339
 340         return ret;
 341 }
 342
 343 static int
 344 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 345               sigset_t *oldset, struct pt_regs *regs)
 346 {
 347         int ret;
 348
 349         /* Are we from a system call? */
 350         if (syscall_get_nr(current, regs) >= 0) {
 351                 /* If so, check system call restarting.. */
 352                 switch (syscall_get_error(current, regs)) {
 353                 case -ERESTART_RESTARTBLOCK:
 354                 case -ERESTARTNOHAND:
 355                         regs->ax = -EINTR;
 356                         break;
 357
 358                 case -ERESTARTSYS:
 359                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 360                                 regs->ax = -EINTR;
 361                                 break;
 362                         }
 363                 /* fallthrough */
 364                 case -ERESTARTNOINTR:
 365                         regs->ax = regs->orig_ax;
 366                         regs->ip -= 2;
 367                         break;
 368                 }
 369         }
 370
 371         /*
 372          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 373          * flag so that register information in the sigcontext is correct.
 374          */
 375         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 376             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 377                 regs->flags &= ~X86_EFLAGS_TF;
 378
 379         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 380
 381         if (ret)
 382                 return ret;
 383
 384 #ifdef CONFIG_X86_64
 385         /*
 386          * This has nothing to do with segment registers,
 387          * despite the name.  This magic affects uaccess.h
 388          * macros' behavior.  Reset it to the normal setting.
 389          */
 390         set_fs(USER_DS);
 391 #endif
 392
 393         /*
 394          * Clear the direction flag as per the ABI for function entry.
 395          */
 396         regs->flags &= ~X86_EFLAGS_DF;
 397
 398         /*
 399          * Clear TF when entering the signal handler, but
 400          * notify any tracer that was single-stepping it.
 401          * The tracer may want to single-step inside the
 402          * handler too.
 403          */
 404         regs->flags &= ~X86_EFLAGS_TF;
 405
 406         spin_lock_irq(&current->sighand->siglock);
 407         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 408         if (!(ka->sa.sa_flags & SA_NODEFER))
 409                 sigaddset(&current->blocked, sig);
 410         recalc_sigpending();
 411         spin_unlock_irq(&current->sighand->siglock);
 412
 413         tracehook_signal_handler(sig, info, ka, regs,
 414                                  test_thread_flag(TIF_SINGLESTEP));
 415
 416         return 0;
 417 }
 418
 419 #ifdef CONFIG_X86_32
 420 #define NR_restart_syscall      __NR_restart_syscall
 421 #else /* !CONFIG_X86_32 */
 422 #define NR_restart_syscall      \
 423         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 424 #endif /* CONFIG_X86_32 */
 425
 426 /*
 427  * Note that 'init' is a special process: it doesn't get signals it doesn't
 428  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 429  * mistake.
 430  */
 431 static void do_signal(struct pt_regs *regs)
 432 {
 433         struct k_sigaction ka;
 434         siginfo_t info;
 435         int signr;
 436         sigset_t *oldset;
 437
 438         /*
 439          * We want the common case to go fast, which is why we may in certain
 440          * cases get here from kernel mode. Just return without doing anything
 441          * if so.
 442          * X86_32: vm86 regs switched out by assembly code before reaching
 443          * here, so testing against kernel CS suffices.
 444          */
 445         if (!user_mode(regs))
 446                 return;
 447
 448         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 449                 oldset = &current->saved_sigmask;
 450         else
 451                 oldset = &current->blocked;
 452
 453         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 454         if (signr > 0) {
 455                 /*
 456                  * Re-enable any watchpoints before delivering the
 457                  * signal to user space. The processor register will
 458                  * have been cleared if the watchpoint triggered
 459                  * inside the kernel.
 460                  */
 461                 if (current->thread.debugreg7)
 462                         set_debugreg(current->thread.debugreg7, 7);
 463
 464                 /* Whee! Actually deliver the signal.  */
 465                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 466                         /*
 467                          * A signal was successfully delivered; the saved
 468                          * sigmask will have been stored in the signal frame,
 469                          * and will be restored by sigreturn, so we can simply
 470                          * clear the TS_RESTORE_SIGMASK flag.
 471                          */
 472                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 473                 }
 474                 return;
 475         }
 476
 477         /* Did we come from a system call? */
 478         if (syscall_get_nr(current, regs) >= 0) {
 479                 /* Restart the system call - no handlers present */
 480                 switch (syscall_get_error(current, regs)) {
 481                 case -ERESTARTNOHAND:
 482                 case -ERESTARTSYS:
 483                 case -ERESTARTNOINTR:
 484                         regs->ax = regs->orig_ax;
 485                         regs->ip -= 2;
 486                         break;
 487
 488                 case -ERESTART_RESTARTBLOCK:
 489                         regs->ax = NR_restart_syscall;
 490                         regs->ip -= 2;
 491                         break;
 492                 }
 493         }
 494
 495         /*
 496          * If there's no signal to deliver, we just put the saved sigmask
 497          * back.
 498          */
 499         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 500                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 501                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 502         }
 503 }
 504
 505 /*
 506  * notification of userspace execution resumption
 507  * - triggered by the TIF_WORK_MASK flags
 508  */
 509 void
 510 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 511 {
 512 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 513         /* notify userspace of pending MCEs */
 514         if (thread_info_flags & _TIF_MCE_NOTIFY)
 515                 mce_notify_user();
 516 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 517
 518         /* deal with pending signal delivery */
 519         if (thread_info_flags & _TIF_SIGPENDING)
 520                 do_signal(regs);
 521
 522         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 523                 clear_thread_flag(TIF_NOTIFY_RESUME);
 524                 tracehook_notify_resume(regs);
 525         }
 526
 527 #ifdef CONFIG_X86_32
 528         clear_thread_flag(TIF_IRET);
 529 #endif /* CONFIG_X86_32 */
 530 }
 531
 532 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 533 {
 534         struct task_struct *me = current;
 535
 536         if (show_unhandled_signals && printk_ratelimit()) {
 537                 printk(KERN_INFO
 538                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 539                        me->comm, me->pid, where, frame,
 540                        regs->ip, regs->sp, regs->orig_ax);
 541                 print_vma_addr(" in ", regs->ip);
 542                 printk(KERN_CONT "\n");
 543         }
 544
 545         force_sig(SIGSEGV, me);
 546 }