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->rsp);
  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(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx);
  68         COPY(rdx); COPY(rcx); COPY(rip);
  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->eflags);
  90                 regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
  91                 regs->orig_rax = -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->rax);
 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 eax;
 123
 124         frame = (struct rt_sigframe __user *)(regs->rsp - 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, &eax))
 139                 goto badframe;
 140
 141 #ifdef DEBUG_SIG
 142         printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs->rip,regs->rsp,frame,eax);
 143 #endif
 144
 145         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
 146                 goto badframe;
 147
 148         return eax;
 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->rdi, &sc->rdi);
 169         err |= __put_user(regs->rsi, &sc->rsi);
 170         err |= __put_user(regs->rbp, &sc->rbp);
 171         err |= __put_user(regs->rsp, &sc->rsp);
 172         err |= __put_user(regs->rbx, &sc->rbx);
 173         err |= __put_user(regs->rdx, &sc->rdx);
 174         err |= __put_user(regs->rcx, &sc->rcx);
 175         err |= __put_user(regs->rax, &sc->rax);
 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->rip, &sc->rip);
 187         err |= __put_user(regs->eflags, &sc->eflags);
 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 rsp;
 202
 203         /* Default to using normal stack - redzone*/
 204         rsp = regs->rsp - 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(rsp) == 0)
 209                         rsp = current->sas_ss_sp + current->sas_ss_size;
 210         }
 211
 212         return (void __user *)round_down(rsp - 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->rsp),
 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 rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
 275 #endif
 276
 277         /* Set up registers for signal handler */
 278         regs->rdi = sig;
 279         /* In case the signal handler was declared without prototypes */
 280         regs->rax = 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->rsi = (unsigned long)&frame->info;
 285         regs->rdx = (unsigned long)&frame->uc;
 286         regs->rip = (unsigned long) ka->sa.sa_handler;
 287
 288         regs->rsp = (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->eflags &= ~TF_MASK;
 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->rip, 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 rip:%lx rsp:%lx regs=%p\n",
 325                 current->pid, sig,
 326                 regs->rip, regs->rsp, regs);
 327 #endif
 328
 329         /* Are we from a system call? */
 330         if ((long)regs->orig_rax >= 0) {
 331                 /* If so, check system call restarting.. */
 332                 switch (regs->rax) {
 333                         case -ERESTART_RESTARTBLOCK:
 334                         case -ERESTARTNOHAND:
 335                                 regs->rax = -EINTR;
 336                                 break;
 337
 338                         case -ERESTARTSYS:
 339                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 340                                         regs->rax = -EINTR;
 341                                         break;
 342                                 }
 343                                 /* fallthrough */
 344                         case -ERESTARTNOINTR:
 345                                 regs->rax = regs->orig_rax;
 346                                 regs->rip -= 2;
 347                                 break;
 348                 }
 349         }
 350
 351         /*
 352          * If TF is set due to a debugger (PT_DTRACE), clear the TF
 353          * flag so that register information in the sigcontext is
 354          * correct.
 355          */
 356         if (unlikely(regs->eflags & TF_MASK)) {
 357                 if (likely(current->ptrace & PT_DTRACE)) {
 358                         current->ptrace &= ~PT_DTRACE;
 359                         regs->eflags &= ~TF_MASK;
 360                 }
 361         }
 362
 363 #ifdef CONFIG_IA32_EMULATION
 364         if (test_thread_flag(TIF_IA32)) {
 365                 if (ka->sa.sa_flags & SA_SIGINFO)
 366                         ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 367                 else
 368                         ret = ia32_setup_frame(sig, ka, oldset, regs);
 369         } else
 370 #endif
 371         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 372
 373         if (ret == 0) {
 374                 spin_lock_irq(&current->sighand->siglock);
 375                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 376                 if (!(ka->sa.sa_flags & SA_NODEFER))
 377                         sigaddset(&current->blocked,sig);
 378                 recalc_sigpending();
 379                 spin_unlock_irq(&current->sighand->siglock);
 380         }
 381
 382         return ret;
 383 }
 384
 385 /*
 386  * Note that 'init' is a special process: it doesn't get signals it doesn't
 387  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 388  * mistake.
 389  */
 390 static void do_signal(struct pt_regs *regs)
 391 {
 392         struct k_sigaction ka;
 393         siginfo_t info;
 394         int signr;
 395         sigset_t *oldset;
 396
 397         /*
 398          * We want the common case to go fast, which
 399          * is why we may in certain cases get here from
 400          * kernel mode. Just return without doing anything
 401          * if so.
 402          */
 403         if (!user_mode(regs))
 404                 return;
 405
 406         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 407                 oldset = &current->saved_sigmask;
 408         else
 409                 oldset = &current->blocked;
 410
 411         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 412         if (signr > 0) {
 413                 /* Reenable any watchpoints before delivering the
 414                  * signal to user space. The processor register will
 415                  * have been cleared if the watchpoint triggered
 416                  * inside the kernel.
 417                  */
 418                 if (current->thread.debugreg7)
 419                         set_debugreg(current->thread.debugreg7, 7);
 420
 421                 /* Whee!  Actually deliver the signal.  */
 422                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 423                         /* a signal was successfully delivered; the saved
 424                          * sigmask will have been stored in the signal frame,
 425                          * and will be restored by sigreturn, so we can simply
 426                          * clear the TIF_RESTORE_SIGMASK flag */
 427                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 428                 }
 429                 return;
 430         }
 431
 432         /* Did we come from a system call? */
 433         if ((long)regs->orig_rax >= 0) {
 434                 /* Restart the system call - no handlers present */
 435                 long res = regs->rax;
 436                 switch (res) {
 437                 case -ERESTARTNOHAND:
 438                 case -ERESTARTSYS:
 439                 case -ERESTARTNOINTR:
 440                         regs->rax = regs->orig_rax;
 441                         regs->rip -= 2;
 442                         break;
 443                 case -ERESTART_RESTARTBLOCK:
 444                         regs->rax = test_thread_flag(TIF_IA32) ?
 445                                         __NR_ia32_restart_syscall :
 446                                         __NR_restart_syscall;
 447                         regs->rip -= 2;
 448                         break;
 449                 }
 450         }
 451
 452         /* if there's no signal to deliver, we just put the saved sigmask
 453            back. */
 454         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 455                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 456                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 457         }
 458 }
 459
 460 void
 461 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 462 {
 463 #ifdef DEBUG_SIG
 464         printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%p pending:%x\n",
 465                thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
 466 #endif
 467
 468         /* Pending single-step? */
 469         if (thread_info_flags & _TIF_SINGLESTEP) {
 470                 regs->eflags |= TF_MASK;
 471                 clear_thread_flag(TIF_SINGLESTEP);
 472         }
 473
 474 #ifdef CONFIG_X86_MCE
 475         /* notify userspace of pending MCEs */
 476         if (thread_info_flags & _TIF_MCE_NOTIFY)
 477                 mce_notify_user();
 478 #endif /* CONFIG_X86_MCE */
 479
 480         /* deal with pending signal delivery */
 481         if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
 482                 do_signal(regs);
 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 rip:%lx rsp:%lx orax:%lx\n",
 490                me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
 491
 492         force_sig(SIGSEGV, me);
 493 }