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 COPYR(x)        err |= __get_user(regs->x, &sc->r ## x)
  66 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  67
  68         COPYR(di); COPYR(si); COPYR(bp); COPYR(sp); COPYR(bx);
  69         COPYR(dx); COPYR(cx); COPYR(ip);
  70         COPY(r8);
  71         COPY(r9);
  72         COPY(r10);
  73         COPY(r11);
  74         COPY(r12);
  75         COPY(r13);
  76         COPY(r14);
  77         COPY(r15);
  78
  79         /* Kernel saves and restores only the CS segment register on signals,
  80          * which is the bare minimum needed to allow mixed 32/64-bit code.
  81          * App's signal handler can save/restore other segments if needed. */
  82         {
  83                 unsigned cs;
  84                 err |= __get_user(cs, &sc->cs);
  85                 regs->cs = cs | 3;      /* Force into user mode */
  86         }
  87
  88         {
  89                 unsigned int tmpflags;
  90                 err |= __get_user(tmpflags, &sc->eflags);
  91                 regs->flags = (regs->flags & ~0x40DD5) | (tmpflags & 0x40DD5);
  92                 regs->orig_ax = -1;             /* disable syscall checks */
  93         }
  94
  95         {
  96                 struct _fpstate __user * buf;
  97                 err |= __get_user(buf, &sc->fpstate);
  98
  99                 if (buf) {
 100                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 101                                 goto badframe;
 102                         err |= restore_i387(buf);
 103                 } else {
 104                         struct task_struct *me = current;
 105                         if (used_math()) {
 106                                 clear_fpu(me);
 107                                 clear_used_math();
 108                         }
 109                 }
 110         }
 111
 112         err |= __get_user(*prax, &sc->rax);
 113         return err;
 114
 115 badframe:
 116         return 1;
 117 }
 118
 119 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 120 {
 121         struct rt_sigframe __user *frame;
 122         sigset_t set;
 123         unsigned long ax;
 124
 125         frame = (struct rt_sigframe __user *)(regs->sp - 8);
 126         if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
 127                 goto badframe;
 128         }
 129         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
 130                 goto badframe;
 131         }
 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 #ifdef DEBUG_SIG
 143         printk("%d sigreturn ip:%lx sp:%lx frame:%p ax:%lx\n",current->pid,regs->ip,regs->sp,frame,ax);
 144 #endif
 145
 146         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 147                 goto badframe;
 148
 149         return ax;
 150
 151 badframe:
 152         signal_fault(regs,frame,"sigreturn");
 153         return 0;
 154 }
 155
 156 /*
 157  * Set up a signal frame.
 158  */
 159
 160 static inline int
 161 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 162 {
 163         int err = 0;
 164
 165         err |= __put_user(regs->cs, &sc->cs);
 166         err |= __put_user(0, &sc->gs);
 167         err |= __put_user(0, &sc->fs);
 168
 169         err |= __put_user(regs->di, &sc->rdi);
 170         err |= __put_user(regs->si, &sc->rsi);
 171         err |= __put_user(regs->bp, &sc->rbp);
 172         err |= __put_user(regs->sp, &sc->rsp);
 173         err |= __put_user(regs->bx, &sc->rbx);
 174         err |= __put_user(regs->dx, &sc->rdx);
 175         err |= __put_user(regs->cx, &sc->rcx);
 176         err |= __put_user(regs->ax, &sc->rax);
 177         err |= __put_user(regs->r8, &sc->r8);
 178         err |= __put_user(regs->r9, &sc->r9);
 179         err |= __put_user(regs->r10, &sc->r10);
 180         err |= __put_user(regs->r11, &sc->r11);
 181         err |= __put_user(regs->r12, &sc->r12);
 182         err |= __put_user(regs->r13, &sc->r13);
 183         err |= __put_user(regs->r14, &sc->r14);
 184         err |= __put_user(regs->r15, &sc->r15);
 185         err |= __put_user(me->thread.trap_no, &sc->trapno);
 186         err |= __put_user(me->thread.error_code, &sc->err);
 187         err |= __put_user(regs->ip, &sc->rip);
 188         err |= __put_user(regs->flags, &sc->eflags);
 189         err |= __put_user(mask, &sc->oldmask);
 190         err |= __put_user(me->thread.cr2, &sc->cr2);
 191
 192         return err;
 193 }
 194
 195 /*
 196  * Determine which stack to use..
 197  */
 198
 199 static void __user *
 200 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
 201 {
 202         unsigned long sp;
 203
 204         /* Default to using normal stack - redzone*/
 205         sp = regs->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, 16);
 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         struct _fpstate __user *fp = NULL;
 221         int err = 0;
 222         struct task_struct *me = current;
 223
 224         if (used_math()) {
 225                 fp = get_stack(ka, regs, sizeof(struct _fpstate));
 226                 frame = (void __user *)round_down(
 227                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 228
 229                 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
 230                         goto give_sigsegv;
 231
 232                 if (save_i387(fp) < 0)
 233                         err |= -1;
 234         } else
 235                 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 236
 237         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 238                 goto give_sigsegv;
 239
 240         if (ka->sa.sa_flags & SA_SIGINFO) {
 241                 err |= copy_siginfo_to_user(&frame->info, info);
 242                 if (err)
 243                         goto give_sigsegv;
 244         }
 245
 246         /* Create the ucontext.  */
 247         err |= __put_user(0, &frame->uc.uc_flags);
 248         err |= __put_user(0, &frame->uc.uc_link);
 249         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 250         err |= __put_user(sas_ss_flags(regs->sp),
 251                           &frame->uc.uc_stack.ss_flags);
 252         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 253         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
 254         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
 255         if (sizeof(*set) == 16) {
 256                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 257                 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 258         } else
 259                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 260
 261         /* Set up to return from userspace.  If provided, use a stub
 262            already in userspace.  */
 263         /* x86-64 should always use SA_RESTORER. */
 264         if (ka->sa.sa_flags & SA_RESTORER) {
 265                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 266         } else {
 267                 /* could use a vstub here */
 268                 goto give_sigsegv;
 269         }
 270
 271         if (err)
 272                 goto give_sigsegv;
 273
 274 #ifdef DEBUG_SIG
 275         printk("%d old ip %lx old sp %lx old ax %lx\n", current->pid,regs->ip,regs->sp,regs->ax);
 276 #endif
 277
 278         /* Set up registers for signal handler */
 279         regs->di = sig;
 280         /* In case the signal handler was declared without prototypes */
 281         regs->ax = 0;
 282
 283         /* This also works for non SA_SIGINFO handlers because they expect the
 284            next argument after the signal number on the stack. */
 285         regs->si = (unsigned long)&frame->info;
 286         regs->dx = (unsigned long)&frame->uc;
 287         regs->ip = (unsigned long) ka->sa.sa_handler;
 288
 289         regs->sp = (unsigned long)frame;
 290
 291         /* Set up the CS register to run signal handlers in 64-bit mode,
 292            even if the handler happens to be interrupting 32-bit code. */
 293         regs->cs = __USER_CS;
 294
 295         /* This, by contrast, has nothing to do with segment registers -
 296            see include/asm-x86_64/uaccess.h for details. */
 297         set_fs(USER_DS);
 298
 299         regs->flags &= ~TF_MASK;
 300         if (test_thread_flag(TIF_SINGLESTEP))
 301                 ptrace_notify(SIGTRAP);
 302 #ifdef DEBUG_SIG
 303         printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n",
 304                 current->comm, current->pid, frame, regs->ip, frame->pretcode);
 305 #endif
 306
 307         return 0;
 308
 309 give_sigsegv:
 310         force_sigsegv(sig, current);
 311         return -EFAULT;
 312 }
 313
 314 /*
 315  * OK, we're invoking a handler
 316  */
 317
 318 static int
 319 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 320                 sigset_t *oldset, struct pt_regs *regs)
 321 {
 322         int ret;
 323
 324 #ifdef DEBUG_SIG
 325         printk("handle_signal pid:%d sig:%lu ip:%lx sp:%lx regs=%p\n",
 326                 current->pid, sig,
 327                 regs->ip, regs->sp, regs);
 328 #endif
 329
 330         /* Are we from a system call? */
 331         if ((long)regs->orig_ax >= 0) {
 332                 /* If so, check system call restarting.. */
 333                 switch (regs->ax) {
 334                         case -ERESTART_RESTARTBLOCK:
 335                         case -ERESTARTNOHAND:
 336                                 regs->ax = -EINTR;
 337                                 break;
 338
 339                         case -ERESTARTSYS:
 340                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 341                                         regs->ax = -EINTR;
 342                                         break;
 343                                 }
 344                                 /* fallthrough */
 345                         case -ERESTARTNOINTR:
 346                                 regs->ax = regs->orig_ax;
 347                                 regs->ip -= 2;
 348                                 break;
 349                 }
 350         }
 351
 352         /*
 353          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 354          * flag so that register information in the sigcontext is correct.
 355          */
 356         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 357             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 358                 regs->flags &= ~X86_EFLAGS_TF;
 359
 360 #ifdef CONFIG_IA32_EMULATION
 361         if (test_thread_flag(TIF_IA32)) {
 362                 if (ka->sa.sa_flags & SA_SIGINFO)
 363                         ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 364                 else
 365                         ret = ia32_setup_frame(sig, ka, oldset, regs);
 366         } else
 367 #endif
 368         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 369
 370         if (ret == 0) {
 371                 spin_lock_irq(&current->sighand->siglock);
 372                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 373                 if (!(ka->sa.sa_flags & SA_NODEFER))
 374                         sigaddset(&current->blocked,sig);
 375                 recalc_sigpending();
 376                 spin_unlock_irq(&current->sighand->siglock);
 377         }
 378
 379         return ret;
 380 }
 381
 382 /*
 383  * Note that 'init' is a special process: it doesn't get signals it doesn't
 384  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 385  * mistake.
 386  */
 387 static void do_signal(struct pt_regs *regs)
 388 {
 389         struct k_sigaction ka;
 390         siginfo_t info;
 391         int signr;
 392         sigset_t *oldset;
 393
 394         /*
 395          * We want the common case to go fast, which
 396          * is why we may in certain cases get here from
 397          * kernel mode. Just return without doing anything
 398          * if so.
 399          */
 400         if (!user_mode(regs))
 401                 return;
 402
 403         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 404                 oldset = &current->saved_sigmask;
 405         else
 406                 oldset = &current->blocked;
 407
 408         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 409         if (signr > 0) {
 410                 /* Re-enable any watchpoints before delivering the
 411                  * signal to user space. The processor register will
 412                  * have been cleared if the watchpoint triggered
 413                  * inside the kernel.
 414                  */
 415                 if (current->thread.debugreg7)
 416                         set_debugreg(current->thread.debugreg7, 7);
 417
 418                 /* Whee!  Actually deliver the signal.  */
 419                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 420                         /* a signal was successfully delivered; the saved
 421                          * sigmask will have been stored in the signal frame,
 422                          * and will be restored by sigreturn, so we can simply
 423                          * clear the TIF_RESTORE_SIGMASK flag */
 424                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 425                 }
 426                 return;
 427         }
 428
 429         /* Did we come from a system call? */
 430         if ((long)regs->orig_ax >= 0) {
 431                 /* Restart the system call - no handlers present */
 432                 long res = regs->ax;
 433                 switch (res) {
 434                 case -ERESTARTNOHAND:
 435                 case -ERESTARTSYS:
 436                 case -ERESTARTNOINTR:
 437                         regs->ax = regs->orig_ax;
 438                         regs->ip -= 2;
 439                         break;
 440                 case -ERESTART_RESTARTBLOCK:
 441                         regs->ax = test_thread_flag(TIF_IA32) ?
 442                                         __NR_ia32_restart_syscall :
 443                                         __NR_restart_syscall;
 444                         regs->ip -= 2;
 445                         break;
 446                 }
 447         }
 448
 449         /* if there's no signal to deliver, we just put the saved sigmask
 450            back. */
 451         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 452                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 453                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 454         }
 455 }
 456
 457 void
 458 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 459 {
 460 #ifdef DEBUG_SIG
 461         printk("do_notify_resume flags:%x ip:%lx sp:%lx caller:%p pending:%x\n",
 462                thread_info_flags, regs->ip, regs->sp, __builtin_return_address(0),signal_pending(current));
 463 #endif
 464
 465         /* Pending single-step? */
 466         if (thread_info_flags & _TIF_SINGLESTEP) {
 467                 regs->flags |= TF_MASK;
 468                 clear_thread_flag(TIF_SINGLESTEP);
 469         }
 470
 471 #ifdef CONFIG_X86_MCE
 472         /* notify userspace of pending MCEs */
 473         if (thread_info_flags & _TIF_MCE_NOTIFY)
 474                 mce_notify_user();
 475 #endif /* CONFIG_X86_MCE */
 476
 477         /* deal with pending signal delivery */
 478         if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
 479                 do_signal(regs);
 480
 481         if (thread_info_flags & _TIF_HRTICK_RESCHED)
 482                 hrtick_resched();
 483 }
 484
 485 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 486 {
 487         struct task_struct *me = current;
 488         if (show_unhandled_signals && printk_ratelimit())
 489                 printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx\n",
 490                me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax);
 491
 492         force_sig(SIGSEGV, me);
 493 }