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/unistd.h>
  19 #include <linux/stddef.h>
  20 #include <linux/personality.h>
  21 #include <linux/compiler.h>
  22 #include <asm/ucontext.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/i387.h>
  25 #include <asm/proto.h>
  26 #include <asm/ia32_unistd.h>
  27 #include <asm/mce.h>
  28
  29 /* #define DEBUG_SIG 1 */
  30
  31 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  32
  33 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  34                sigset_t *set, struct pt_regs * regs);
  35 int ia32_setup_frame(int sig, struct k_sigaction *ka,
  36             sigset_t *set, struct pt_regs * regs);
  37
  38 asmlinkage long
  39 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  40                 struct pt_regs *regs)
  41 {
  42         return do_sigaltstack(uss, uoss, regs->sp);
  43 }
  44
  45
  46 /*
  47  * Do a signal return; undo the signal stack.
  48  */
  49
  50 struct rt_sigframe
  51 {
  52         char __user *pretcode;
  53         struct ucontext uc;
  54         struct siginfo info;
  55 };
  56
  57 static int
  58 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
  59 {
  60         unsigned int err = 0;
  61
  62         /* Always make any pending restarted system calls return -EINTR */
  63         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  64
  65 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  66
  67         COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  68         COPY(dx); COPY(cx); COPY(ip);
  69         COPY(r8);
  70         COPY(r9);
  71         COPY(r10);
  72         COPY(r11);
  73         COPY(r12);
  74         COPY(r13);
  75         COPY(r14);
  76         COPY(r15);
  77
  78         /* Kernel saves and restores only the CS segment register on signals,
  79          * which is the bare minimum needed to allow mixed 32/64-bit code.
  80          * App's signal handler can save/restore other segments if needed. */
  81         {
  82                 unsigned cs;
  83                 err |= __get_user(cs, &sc->cs);
  84                 regs->cs = cs | 3;      /* Force into user mode */
  85         }
  86
  87         {
  88                 unsigned int tmpflags;
  89                 err |= __get_user(tmpflags, &sc->flags);
  90                 regs->flags = (regs->flags & ~0x40DD5) | (tmpflags & 0x40DD5);
  91                 regs->orig_ax = -1;             /* disable syscall checks */
  92         }
  93
  94         {
  95                 struct _fpstate __user * buf;
  96                 err |= __get_user(buf, &sc->fpstate);
  97
  98                 if (buf) {
  99                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 100                                 goto badframe;
 101                         err |= restore_i387(buf);
 102                 } else {
 103                         struct task_struct *me = current;
 104                         if (used_math()) {
 105                                 clear_fpu(me);
 106                                 clear_used_math();
 107                         }
 108                 }
 109         }
 110
 111         err |= __get_user(*prax, &sc->ax);
 112         return err;
 113
 114 badframe:
 115         return 1;
 116 }
 117
 118 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 119 {
 120         struct rt_sigframe __user *frame;
 121         sigset_t set;
 122         unsigned long ax;
 123
 124         frame = (struct rt_sigframe __user *)(regs->sp - 8);
 125         if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
 126                 goto badframe;
 127         }
 128         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
 129                 goto badframe;
 130         }
 131
 132         sigdelsetmask(&set, ~_BLOCKABLE);
 133         spin_lock_irq(&current->sighand->siglock);
 134         current->blocked = set;
 135         recalc_sigpending();
 136         spin_unlock_irq(&current->sighand->siglock);
 137
 138         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 139                 goto badframe;
 140
 141 #ifdef DEBUG_SIG
 142         printk("%d sigreturn ip:%lx sp:%lx frame:%p ax:%lx\n",current->pid,regs->ip,regs->sp,frame,ax);
 143 #endif
 144
 145         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 146                 goto badframe;
 147
 148         return ax;
 149
 150 badframe:
 151         signal_fault(regs,frame,"sigreturn");
 152         return 0;
 153 }
 154
 155 /*
 156  * Set up a signal frame.
 157  */
 158
 159 static inline int
 160 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 161 {
 162         int err = 0;
 163
 164         err |= __put_user(regs->cs, &sc->cs);
 165         err |= __put_user(0, &sc->gs);
 166         err |= __put_user(0, &sc->fs);
 167
 168         err |= __put_user(regs->di, &sc->di);
 169         err |= __put_user(regs->si, &sc->si);
 170         err |= __put_user(regs->bp, &sc->bp);
 171         err |= __put_user(regs->sp, &sc->sp);
 172         err |= __put_user(regs->bx, &sc->bx);
 173         err |= __put_user(regs->dx, &sc->dx);
 174         err |= __put_user(regs->cx, &sc->cx);
 175         err |= __put_user(regs->ax, &sc->ax);
 176         err |= __put_user(regs->r8, &sc->r8);
 177         err |= __put_user(regs->r9, &sc->r9);
 178         err |= __put_user(regs->r10, &sc->r10);
 179         err |= __put_user(regs->r11, &sc->r11);
 180         err |= __put_user(regs->r12, &sc->r12);
 181         err |= __put_user(regs->r13, &sc->r13);
 182         err |= __put_user(regs->r14, &sc->r14);
 183         err |= __put_user(regs->r15, &sc->r15);
 184         err |= __put_user(me->thread.trap_no, &sc->trapno);
 185         err |= __put_user(me->thread.error_code, &sc->err);
 186         err |= __put_user(regs->ip, &sc->ip);
 187         err |= __put_user(regs->flags, &sc->flags);
 188         err |= __put_user(mask, &sc->oldmask);
 189         err |= __put_user(me->thread.cr2, &sc->cr2);
 190
 191         return err;
 192 }
 193
 194 /*
 195  * Determine which stack to use..
 196  */
 197
 198 static void __user *
 199 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
 200 {
 201         unsigned long sp;
 202
 203         /* Default to using normal stack - redzone*/
 204         sp = regs->sp - 128;
 205
 206         /* This is the X/Open sanctioned signal stack switching.  */
 207         if (ka->sa.sa_flags & SA_ONSTACK) {
 208                 if (sas_ss_flags(sp) == 0)
 209                         sp = current->sas_ss_sp + current->sas_ss_size;
 210         }
 211
 212         return (void __user *)round_down(sp - size, 16);
 213 }
 214
 215 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 216                            sigset_t *set, struct pt_regs * regs)
 217 {
 218         struct rt_sigframe __user *frame;
 219         struct _fpstate __user *fp = NULL;
 220         int err = 0;
 221         struct task_struct *me = current;
 222
 223         if (used_math()) {
 224                 fp = get_stack(ka, regs, sizeof(struct _fpstate));
 225                 frame = (void __user *)round_down(
 226                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 227
 228                 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
 229                         goto give_sigsegv;
 230
 231                 if (save_i387(fp) < 0)
 232                         err |= -1;
 233         } else
 234                 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 235
 236         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 237                 goto give_sigsegv;
 238
 239         if (ka->sa.sa_flags & SA_SIGINFO) {
 240                 err |= copy_siginfo_to_user(&frame->info, info);
 241                 if (err)
 242                         goto give_sigsegv;
 243         }
 244
 245         /* Create the ucontext.  */
 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                 goto give_sigsegv;
 268         }
 269
 270         if (err)
 271                 goto give_sigsegv;
 272
 273 #ifdef DEBUG_SIG
 274         printk("%d old ip %lx old sp %lx old ax %lx\n", current->pid,regs->ip,regs->sp,regs->ax);
 275 #endif
 276
 277         /* Set up registers for signal handler */
 278         regs->di = sig;
 279         /* In case the signal handler was declared without prototypes */
 280         regs->ax = 0;
 281
 282         /* This also works for non SA_SIGINFO handlers because they expect the
 283            next argument after the signal number on the stack. */
 284         regs->si = (unsigned long)&frame->info;
 285         regs->dx = (unsigned long)&frame->uc;
 286         regs->ip = (unsigned long) ka->sa.sa_handler;
 287
 288         regs->sp = (unsigned long)frame;
 289
 290         /* Set up the CS register to run signal handlers in 64-bit mode,
 291            even if the handler happens to be interrupting 32-bit code. */
 292         regs->cs = __USER_CS;
 293
 294         /* This, by contrast, has nothing to do with segment registers -
 295            see include/asm-x86_64/uaccess.h for details. */
 296         set_fs(USER_DS);
 297
 298         regs->flags &= ~X86_EFLAGS_TF;
 299         if (test_thread_flag(TIF_SINGLESTEP))
 300                 ptrace_notify(SIGTRAP);
 301 #ifdef DEBUG_SIG
 302         printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n",
 303                 current->comm, current->pid, frame, regs->ip, frame->pretcode);
 304 #endif
 305
 306         return 0;
 307
 308 give_sigsegv:
 309         force_sigsegv(sig, current);
 310         return -EFAULT;
 311 }
 312
 313 /*
 314  * OK, we're invoking a handler
 315  */
 316
 317 static int
 318 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 319                 sigset_t *oldset, struct pt_regs *regs)
 320 {
 321         int ret;
 322
 323 #ifdef DEBUG_SIG
 324         printk("handle_signal pid:%d sig:%lu ip:%lx sp:%lx regs=%p\n",
 325                 current->pid, sig,
 326                 regs->ip, regs->sp, regs);
 327 #endif
 328
 329         /* Are we from a system call? */
 330         if ((long)regs->orig_ax >= 0) {
 331                 /* If so, check system call restarting.. */
 332                 switch (regs->ax) {
 333                         case -ERESTART_RESTARTBLOCK:
 334                         case -ERESTARTNOHAND:
 335                                 regs->ax = -EINTR;
 336                                 break;
 337
 338                         case -ERESTARTSYS:
 339                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 340                                         regs->ax = -EINTR;
 341                                         break;
 342                                 }
 343                                 /* fallthrough */
 344                         case -ERESTARTNOINTR:
 345                                 regs->ax = regs->orig_ax;
 346                                 regs->ip -= 2;
 347                                 break;
 348                 }
 349         }
 350
 351         /*
 352          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 353          * flag so that register information in the sigcontext is correct.
 354          */
 355         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 356             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 357                 regs->flags &= ~X86_EFLAGS_TF;
 358
 359 #ifdef CONFIG_IA32_EMULATION
 360         if (test_thread_flag(TIF_IA32)) {
 361                 if (ka->sa.sa_flags & SA_SIGINFO)
 362                         ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 363                 else
 364                         ret = ia32_setup_frame(sig, ka, oldset, regs);
 365         } else
 366 #endif
 367         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 368
 369         if (ret == 0) {
 370                 spin_lock_irq(&current->sighand->siglock);
 371                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 372                 if (!(ka->sa.sa_flags & SA_NODEFER))
 373                         sigaddset(&current->blocked,sig);
 374                 recalc_sigpending();
 375                 spin_unlock_irq(&current->sighand->siglock);
 376         }
 377
 378         return ret;
 379 }
 380
 381 /*
 382  * Note that 'init' is a special process: it doesn't get signals it doesn't
 383  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 384  * mistake.
 385  */
 386 static void do_signal(struct pt_regs *regs)
 387 {
 388         struct k_sigaction ka;
 389         siginfo_t info;
 390         int signr;
 391         sigset_t *oldset;
 392
 393         /*
 394          * We want the common case to go fast, which
 395          * is why we may in certain cases get here from
 396          * kernel mode. Just return without doing anything
 397          * if so.
 398          */
 399         if (!user_mode(regs))
 400                 return;
 401
 402         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 403                 oldset = &current->saved_sigmask;
 404         else
 405                 oldset = &current->blocked;
 406
 407         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 408         if (signr > 0) {
 409                 /* Re-enable any watchpoints before delivering the
 410                  * signal to user space. The processor register will
 411                  * have been cleared if the watchpoint triggered
 412                  * inside the kernel.
 413                  */
 414                 if (current->thread.debugreg7)
 415                         set_debugreg(current->thread.debugreg7, 7);
 416
 417                 /* Whee!  Actually deliver the signal.  */
 418                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 419                         /* a signal was successfully delivered; the saved
 420                          * sigmask will have been stored in the signal frame,
 421                          * and will be restored by sigreturn, so we can simply
 422                          * clear the TIF_RESTORE_SIGMASK flag */
 423                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 424                 }
 425                 return;
 426         }
 427
 428         /* Did we come from a system call? */
 429         if ((long)regs->orig_ax >= 0) {
 430                 /* Restart the system call - no handlers present */
 431                 long res = regs->ax;
 432                 switch (res) {
 433                 case -ERESTARTNOHAND:
 434                 case -ERESTARTSYS:
 435                 case -ERESTARTNOINTR:
 436                         regs->ax = regs->orig_ax;
 437                         regs->ip -= 2;
 438                         break;
 439                 case -ERESTART_RESTARTBLOCK:
 440                         regs->ax = test_thread_flag(TIF_IA32) ?
 441                                         __NR_ia32_restart_syscall :
 442                                         __NR_restart_syscall;
 443                         regs->ip -= 2;
 444                         break;
 445                 }
 446         }
 447
 448         /* if there's no signal to deliver, we just put the saved sigmask
 449            back. */
 450         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 451                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 452                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 453         }
 454 }
 455
 456 void
 457 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 458 {
 459 #ifdef DEBUG_SIG
 460         printk("do_notify_resume flags:%x ip:%lx sp:%lx caller:%p pending:%x\n",
 461                thread_info_flags, regs->ip, regs->sp, __builtin_return_address(0),signal_pending(current));
 462 #endif
 463
 464         /* Pending single-step? */
 465         if (thread_info_flags & _TIF_SINGLESTEP) {
 466                 regs->flags |= X86_EFLAGS_TF;
 467                 clear_thread_flag(TIF_SINGLESTEP);
 468         }
 469
 470 #ifdef CONFIG_X86_MCE
 471         /* notify userspace of pending MCEs */
 472         if (thread_info_flags & _TIF_MCE_NOTIFY)
 473                 mce_notify_user();
 474 #endif /* CONFIG_X86_MCE */
 475
 476         /* deal with pending signal delivery */
 477         if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
 478                 do_signal(regs);
 479
 480         if (thread_info_flags & _TIF_HRTICK_RESCHED)
 481                 hrtick_resched();
 482 }
 483
 484 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 485 {
 486         struct task_struct *me = current;
 487         if (show_unhandled_signals && printk_ratelimit()) {
 488                 printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 489                me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax);
 490                 print_vma_addr(" in ", regs->ip);
 491                 printk("\n");
 492         }
 493
 494         force_sig(SIGSEGV, me);
 495 }