arch/x86_64/kernel/signal.c

   1 /*
   2  *  linux/arch/x86_64/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
   6  *
   7  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   8  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   9  *  2000-2002   x86-64 support by Andi Kleen
  10  *
  11  *  $Id: signal.c,v 1.18 2001/10/17 22:30:37 ak Exp $
  12  */
  13
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/smp_lock.h>
  18 #include <linux/kernel.h>
  19 #include <linux/signal.h>
  20 #include <linux/errno.h>
  21 #include <linux/wait.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/unistd.h>
  24 #include <linux/stddef.h>
  25 #include <linux/personality.h>
  26 #include <linux/compiler.h>
  27 #include <asm/ucontext.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/i387.h>
  30 #include <asm/proto.h>
  31 #include <asm/ia32_unistd.h>
  32
  33 /* #define DEBUG_SIG 1 */
  34
  35 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  36
  37 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  38                sigset_t *set, struct pt_regs * regs);
  39 int ia32_setup_frame(int sig, struct k_sigaction *ka,
  40             sigset_t *set, struct pt_regs * regs);
  41
  42 asmlinkage long
  43 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  44 {
  45         sigset_t saveset, newset;
  46
  47         /* XXX: Don't preclude handling different sized sigset_t's.  */
  48         if (sigsetsize != sizeof(sigset_t))
  49                 return -EINVAL;
  50
  51         if (copy_from_user(&newset, unewset, sizeof(newset)))
  52                 return -EFAULT;
  53         sigdelsetmask(&newset, ~_BLOCKABLE);
  54
  55         spin_lock_irq(&current->sighand->siglock);
  56         saveset = current->blocked;
  57         current->blocked = newset;
  58         recalc_sigpending();
  59         spin_unlock_irq(&current->sighand->siglock);
  60 #ifdef DEBUG_SIG
  61         printk("rt_sigsuspend savset(%lx) newset(%lx) regs(%p) rip(%lx)\n",
  62                 saveset, newset, regs, regs->rip);
  63 #endif
  64         regs->rax = -EINTR;
  65         while (1) {
  66                 current->state = TASK_INTERRUPTIBLE;
  67                 schedule();
  68                 if (do_signal(regs, &saveset))
  69                         return -EINTR;
  70         }
  71 }
  72
  73 asmlinkage long
  74 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  75                 struct pt_regs *regs)
  76 {
  77         return do_sigaltstack(uss, uoss, regs->rsp);
  78 }
  79
  80
  81 /*
  82  * Do a signal return; undo the signal stack.
  83  */
  84
  85 struct rt_sigframe
  86 {
  87         char __user *pretcode;
  88         struct ucontext uc;
  89         struct siginfo info;
  90 };
  91
  92 static int
  93 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
  94 {
  95         unsigned int err = 0;
  96
  97         /* Always make any pending restarted system calls return -EINTR */
  98         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  99
 100 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
 101
 102         COPY(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx);
 103         COPY(rdx); COPY(rcx); COPY(rip);
 104         COPY(r8);
 105         COPY(r9);
 106         COPY(r10);
 107         COPY(r11);
 108         COPY(r12);
 109         COPY(r13);
 110         COPY(r14);
 111         COPY(r15);
 112
 113         {
 114                 unsigned int tmpflags;
 115                 err |= __get_user(tmpflags, &sc->eflags);
 116                 regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
 117                 regs->orig_rax = -1;            /* disable syscall checks */
 118         }
 119
 120         {
 121                 struct _fpstate __user * buf;
 122                 err |= __get_user(buf, &sc->fpstate);
 123
 124                 if (buf) {
 125                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 126                                 goto badframe;
 127                         err |= restore_i387(buf);
 128                 } else {
 129                         struct task_struct *me = current;
 130                         if (used_math()) {
 131                                 clear_fpu(me);
 132                                 clear_used_math();
 133                         }
 134                 }
 135         }
 136
 137         err |= __get_user(*prax, &sc->rax);
 138         return err;
 139
 140 badframe:
 141         return 1;
 142 }
 143
 144 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 145 {
 146         struct rt_sigframe __user *frame;
 147         sigset_t set;
 148         unsigned long eax;
 149
 150         frame = (struct rt_sigframe __user *)(regs->rsp - 8);
 151         if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
 152                 goto badframe;
 153         }
 154         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
 155                 goto badframe;
 156         }
 157
 158         sigdelsetmask(&set, ~_BLOCKABLE);
 159         spin_lock_irq(&current->sighand->siglock);
 160         current->blocked = set;
 161         recalc_sigpending();
 162         spin_unlock_irq(&current->sighand->siglock);
 163
 164         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
 165                 goto badframe;
 166
 167 #ifdef DEBUG_SIG
 168         printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs.rip,regs.rsp,frame,eax);
 169 #endif
 170
 171         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
 172                 goto badframe;
 173
 174         return eax;
 175
 176 badframe:
 177         signal_fault(regs,frame,"sigreturn");
 178         return 0;
 179 }
 180
 181 /*
 182  * Set up a signal frame.
 183  */
 184
 185 static inline int
 186 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 187 {
 188         int err = 0;
 189
 190         err |= __put_user(0, &sc->gs);
 191         err |= __put_user(0, &sc->fs);
 192
 193         err |= __put_user(regs->rdi, &sc->rdi);
 194         err |= __put_user(regs->rsi, &sc->rsi);
 195         err |= __put_user(regs->rbp, &sc->rbp);
 196         err |= __put_user(regs->rsp, &sc->rsp);
 197         err |= __put_user(regs->rbx, &sc->rbx);
 198         err |= __put_user(regs->rdx, &sc->rdx);
 199         err |= __put_user(regs->rcx, &sc->rcx);
 200         err |= __put_user(regs->rax, &sc->rax);
 201         err |= __put_user(regs->r8, &sc->r8);
 202         err |= __put_user(regs->r9, &sc->r9);
 203         err |= __put_user(regs->r10, &sc->r10);
 204         err |= __put_user(regs->r11, &sc->r11);
 205         err |= __put_user(regs->r12, &sc->r12);
 206         err |= __put_user(regs->r13, &sc->r13);
 207         err |= __put_user(regs->r14, &sc->r14);
 208         err |= __put_user(regs->r15, &sc->r15);
 209         err |= __put_user(me->thread.trap_no, &sc->trapno);
 210         err |= __put_user(me->thread.error_code, &sc->err);
 211         err |= __put_user(regs->rip, &sc->rip);
 212         err |= __put_user(regs->eflags, &sc->eflags);
 213         err |= __put_user(mask, &sc->oldmask);
 214         err |= __put_user(me->thread.cr2, &sc->cr2);
 215
 216         return err;
 217 }
 218
 219 /*
 220  * Determine which stack to use..
 221  */
 222
 223 static void __user *
 224 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
 225 {
 226         unsigned long rsp;
 227
 228         /* Default to using normal stack - redzone*/
 229         rsp = regs->rsp - 128;
 230
 231         /* This is the X/Open sanctioned signal stack switching.  */
 232         /* RED-PEN: redzone on that stack? */
 233         if (ka->sa.sa_flags & SA_ONSTACK) {
 234                 if (sas_ss_flags(rsp) == 0)
 235                         rsp = current->sas_ss_sp + current->sas_ss_size;
 236         }
 237
 238         return (void __user *)round_down(rsp - size, 16);
 239 }
 240
 241 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 242                            sigset_t *set, struct pt_regs * regs)
 243 {
 244         struct rt_sigframe __user *frame;
 245         struct _fpstate __user *fp = NULL;
 246         int err = 0;
 247         struct task_struct *me = current;
 248
 249         if (used_math()) {
 250                 fp = get_stack(ka, regs, sizeof(struct _fpstate));
 251                 frame = (void __user *)round_down(
 252                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 253
 254                 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
 255                         goto give_sigsegv;
 256
 257                 if (save_i387(fp) < 0)
 258                         err |= -1;
 259         } else
 260                 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 261
 262         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 263                 goto give_sigsegv;
 264
 265         if (ka->sa.sa_flags & SA_SIGINFO) {
 266                 err |= copy_siginfo_to_user(&frame->info, info);
 267                 if (err)
 268                         goto give_sigsegv;
 269         }
 270
 271         /* Create the ucontext.  */
 272         err |= __put_user(0, &frame->uc.uc_flags);
 273         err |= __put_user(0, &frame->uc.uc_link);
 274         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 275         err |= __put_user(sas_ss_flags(regs->rsp),
 276                           &frame->uc.uc_stack.ss_flags);
 277         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 278         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
 279         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
 280         if (sizeof(*set) == 16) {
 281                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 282                 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 283         } else
 284                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 285
 286         /* Set up to return from userspace.  If provided, use a stub
 287            already in userspace.  */
 288         /* x86-64 should always use SA_RESTORER. */
 289         if (ka->sa.sa_flags & SA_RESTORER) {
 290                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 291         } else {
 292                 /* could use a vstub here */
 293                 goto give_sigsegv;
 294         }
 295
 296         if (err)
 297                 goto give_sigsegv;
 298
 299 #ifdef DEBUG_SIG
 300         printk("%d old rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
 301 #endif
 302
 303         /* Set up registers for signal handler */
 304         {
 305                 struct exec_domain *ed = current_thread_info()->exec_domain;
 306                 if (unlikely(ed && ed->signal_invmap && sig < 32))
 307                         sig = ed->signal_invmap[sig];
 308         }
 309         regs->rdi = sig;
 310         /* In case the signal handler was declared without prototypes */
 311         regs->rax = 0;
 312
 313         /* This also works for non SA_SIGINFO handlers because they expect the
 314            next argument after the signal number on the stack. */
 315         regs->rsi = (unsigned long)&frame->info;
 316         regs->rdx = (unsigned long)&frame->uc;
 317         regs->rip = (unsigned long) ka->sa.sa_handler;
 318
 319         regs->rsp = (unsigned long)frame;
 320
 321         set_fs(USER_DS);
 322         regs->eflags &= ~TF_MASK;
 323         if (test_thread_flag(TIF_SINGLESTEP))
 324                 ptrace_notify(SIGTRAP);
 325 #ifdef DEBUG_SIG
 326         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 327                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 328 #endif
 329
 330         return 1;
 331
 332 give_sigsegv:
 333         force_sigsegv(sig, current);
 334         return 0;
 335 }
 336
 337 /*
 338  * OK, we're invoking a handler
 339  */
 340
 341 static int
 342 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 343                 sigset_t *oldset, struct pt_regs *regs)
 344 {
 345         int ret;
 346
 347 #ifdef DEBUG_SIG
 348         printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
 349                 current->pid, sig,
 350                 regs->rip, regs->rsp, regs);
 351 #endif
 352
 353         /* Are we from a system call? */
 354         if ((long)regs->orig_rax >= 0) {
 355                 /* If so, check system call restarting.. */
 356                 switch (regs->rax) {
 357                         case -ERESTART_RESTARTBLOCK:
 358                         case -ERESTARTNOHAND:
 359                                 regs->rax = -EINTR;
 360                                 break;
 361
 362                         case -ERESTARTSYS:
 363                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 364                                         regs->rax = -EINTR;
 365                                         break;
 366                                 }
 367                                 /* fallthrough */
 368                         case -ERESTARTNOINTR:
 369                                 regs->rax = regs->orig_rax;
 370                                 regs->rip -= 2;
 371                                 break;
 372                 }
 373         }
 374
 375         /*
 376          * If TF is set due to a debugger (PT_DTRACE), clear the TF
 377          * flag so that register information in the sigcontext is
 378          * correct.
 379          */
 380         if (unlikely(regs->eflags & TF_MASK)) {
 381                 if (likely(current->ptrace & PT_DTRACE)) {
 382                         current->ptrace &= ~PT_DTRACE;
 383                         regs->eflags &= ~TF_MASK;
 384                 }
 385         }
 386
 387 #ifdef CONFIG_IA32_EMULATION
 388         if (test_thread_flag(TIF_IA32)) {
 389                 if (ka->sa.sa_flags & SA_SIGINFO)
 390                         ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 391                 else
 392                         ret = ia32_setup_frame(sig, ka, oldset, regs);
 393         } else
 394 #endif
 395         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 396
 397         if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
 398                 spin_lock_irq(&current->sighand->siglock);
 399                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 400                 sigaddset(&current->blocked,sig);
 401                 recalc_sigpending();
 402                 spin_unlock_irq(&current->sighand->siglock);
 403         }
 404
 405         return ret;
 406 }
 407
 408 /*
 409  * Note that 'init' is a special process: it doesn't get signals it doesn't
 410  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 411  * mistake.
 412  */
 413 int do_signal(struct pt_regs *regs, sigset_t *oldset)
 414 {
 415         struct k_sigaction ka;
 416         siginfo_t info;
 417         int signr;
 418
 419         /*
 420          * We want the common case to go fast, which
 421          * is why we may in certain cases get here from
 422          * kernel mode. Just return without doing anything
 423          * if so.
 424          */
 425         if ((regs->cs & 3) != 3)
 426                 return 1;
 427
 428         if (try_to_freeze(0))
 429                 goto no_signal;
 430
 431         if (!oldset)
 432                 oldset = &current->blocked;
 433
 434         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 435         if (signr > 0) {
 436                 /* Reenable any watchpoints before delivering the
 437                  * signal to user space. The processor register will
 438                  * have been cleared if the watchpoint triggered
 439                  * inside the kernel.
 440                  */
 441                 if (current->thread.debugreg7)
 442                         asm volatile("movq %0,%%db7"    : : "r" (current->thread.debugreg7));
 443
 444                 /* Whee!  Actually deliver the signal.  */
 445                 return handle_signal(signr, &info, &ka, oldset, regs);
 446         }
 447
 448  no_signal:
 449         /* Did we come from a system call? */
 450         if ((long)regs->orig_rax >= 0) {
 451                 /* Restart the system call - no handlers present */
 452                 long res = regs->rax;
 453                 if (res == -ERESTARTNOHAND ||
 454                     res == -ERESTARTSYS ||
 455                     res == -ERESTARTNOINTR) {
 456                         regs->rax = regs->orig_rax;
 457                         regs->rip -= 2;
 458                 }
 459                 if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
 460                         regs->rax = test_thread_flag(TIF_IA32) ?
 461                                         __NR_ia32_restart_syscall :
 462                                         __NR_restart_syscall;
 463                         regs->rip -= 2;
 464                 }
 465         }
 466         return 0;
 467 }
 468
 469 void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
 470 {
 471 #ifdef DEBUG_SIG
 472         printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
 473                thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
 474 #endif
 475
 476         /* Pending single-step? */
 477         if (thread_info_flags & _TIF_SINGLESTEP) {
 478                 regs->eflags |= TF_MASK;
 479                 clear_thread_flag(TIF_SINGLESTEP);
 480         }
 481
 482         /* deal with pending signal delivery */
 483         if (thread_info_flags & _TIF_SIGPENDING)
 484                 do_signal(regs,oldset);
 485 }
 486
 487 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 488 {
 489         struct task_struct *me = current;
 490         if (exception_trace)
 491                 printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
 492                me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
 493
 494         force_sig(SIGSEGV, me);
 495 }