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         /* Kernel saves and restores only the CS segment register on signals,
 114          * which is the bare minimum needed to allow mixed 32/64-bit code.
 115          * App's signal handler can save/restore other segments if needed. */
 116         {
 117                 unsigned cs;
 118                 err |= __get_user(cs, &sc->cs);
 119                 regs->cs = cs | 3;      /* Force into user mode */
 120         }
 121
 122         {
 123                 unsigned int tmpflags;
 124                 err |= __get_user(tmpflags, &sc->eflags);
 125                 regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
 126                 regs->orig_rax = -1;            /* disable syscall checks */
 127         }
 128
 129         {
 130                 struct _fpstate __user * buf;
 131                 err |= __get_user(buf, &sc->fpstate);
 132
 133                 if (buf) {
 134                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 135                                 goto badframe;
 136                         err |= restore_i387(buf);
 137                 } else {
 138                         struct task_struct *me = current;
 139                         if (used_math()) {
 140                                 clear_fpu(me);
 141                                 clear_used_math();
 142                         }
 143                 }
 144         }
 145
 146         err |= __get_user(*prax, &sc->rax);
 147         return err;
 148
 149 badframe:
 150         return 1;
 151 }
 152
 153 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 154 {
 155         struct rt_sigframe __user *frame;
 156         sigset_t set;
 157         unsigned long eax;
 158
 159         frame = (struct rt_sigframe __user *)(regs->rsp - 8);
 160         if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
 161                 goto badframe;
 162         }
 163         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
 164                 goto badframe;
 165         }
 166
 167         sigdelsetmask(&set, ~_BLOCKABLE);
 168         spin_lock_irq(&current->sighand->siglock);
 169         current->blocked = set;
 170         recalc_sigpending();
 171         spin_unlock_irq(&current->sighand->siglock);
 172
 173         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
 174                 goto badframe;
 175
 176 #ifdef DEBUG_SIG
 177         printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs.rip,regs.rsp,frame,eax);
 178 #endif
 179
 180         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
 181                 goto badframe;
 182
 183         return eax;
 184
 185 badframe:
 186         signal_fault(regs,frame,"sigreturn");
 187         return 0;
 188 }
 189
 190 /*
 191  * Set up a signal frame.
 192  */
 193
 194 static inline int
 195 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 196 {
 197         int err = 0;
 198
 199         err |= __put_user(regs->cs, &sc->cs);
 200         err |= __put_user(0, &sc->gs);
 201         err |= __put_user(0, &sc->fs);
 202
 203         err |= __put_user(regs->rdi, &sc->rdi);
 204         err |= __put_user(regs->rsi, &sc->rsi);
 205         err |= __put_user(regs->rbp, &sc->rbp);
 206         err |= __put_user(regs->rsp, &sc->rsp);
 207         err |= __put_user(regs->rbx, &sc->rbx);
 208         err |= __put_user(regs->rdx, &sc->rdx);
 209         err |= __put_user(regs->rcx, &sc->rcx);
 210         err |= __put_user(regs->rax, &sc->rax);
 211         err |= __put_user(regs->r8, &sc->r8);
 212         err |= __put_user(regs->r9, &sc->r9);
 213         err |= __put_user(regs->r10, &sc->r10);
 214         err |= __put_user(regs->r11, &sc->r11);
 215         err |= __put_user(regs->r12, &sc->r12);
 216         err |= __put_user(regs->r13, &sc->r13);
 217         err |= __put_user(regs->r14, &sc->r14);
 218         err |= __put_user(regs->r15, &sc->r15);
 219         err |= __put_user(me->thread.trap_no, &sc->trapno);
 220         err |= __put_user(me->thread.error_code, &sc->err);
 221         err |= __put_user(regs->rip, &sc->rip);
 222         err |= __put_user(regs->eflags, &sc->eflags);
 223         err |= __put_user(mask, &sc->oldmask);
 224         err |= __put_user(me->thread.cr2, &sc->cr2);
 225
 226         return err;
 227 }
 228
 229 /*
 230  * Determine which stack to use..
 231  */
 232
 233 static void __user *
 234 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
 235 {
 236         unsigned long rsp;
 237
 238         /* Default to using normal stack - redzone*/
 239         rsp = regs->rsp - 128;
 240
 241         /* This is the X/Open sanctioned signal stack switching.  */
 242         /* RED-PEN: redzone on that stack? */
 243         if (ka->sa.sa_flags & SA_ONSTACK) {
 244                 if (sas_ss_flags(rsp) == 0)
 245                         rsp = current->sas_ss_sp + current->sas_ss_size;
 246         }
 247
 248         return (void __user *)round_down(rsp - size, 16);
 249 }
 250
 251 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 252                            sigset_t *set, struct pt_regs * regs)
 253 {
 254         struct rt_sigframe __user *frame;
 255         struct _fpstate __user *fp = NULL;
 256         int err = 0;
 257         struct task_struct *me = current;
 258
 259         if (used_math()) {
 260                 fp = get_stack(ka, regs, sizeof(struct _fpstate));
 261                 frame = (void __user *)round_down(
 262                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 263
 264                 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
 265                         goto give_sigsegv;
 266
 267                 if (save_i387(fp) < 0)
 268                         err |= -1;
 269         } else
 270                 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 271
 272         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 273                 goto give_sigsegv;
 274
 275         if (ka->sa.sa_flags & SA_SIGINFO) {
 276                 err |= copy_siginfo_to_user(&frame->info, info);
 277                 if (err)
 278                         goto give_sigsegv;
 279         }
 280
 281         /* Create the ucontext.  */
 282         err |= __put_user(0, &frame->uc.uc_flags);
 283         err |= __put_user(0, &frame->uc.uc_link);
 284         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 285         err |= __put_user(sas_ss_flags(regs->rsp),
 286                           &frame->uc.uc_stack.ss_flags);
 287         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 288         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
 289         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
 290         if (sizeof(*set) == 16) {
 291                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 292                 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 293         } else
 294                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 295
 296         /* Set up to return from userspace.  If provided, use a stub
 297            already in userspace.  */
 298         /* x86-64 should always use SA_RESTORER. */
 299         if (ka->sa.sa_flags & SA_RESTORER) {
 300                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 301         } else {
 302                 /* could use a vstub here */
 303                 goto give_sigsegv;
 304         }
 305
 306         if (err)
 307                 goto give_sigsegv;
 308
 309 #ifdef DEBUG_SIG
 310         printk("%d old rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
 311 #endif
 312
 313         /* Set up registers for signal handler */
 314         {
 315                 struct exec_domain *ed = current_thread_info()->exec_domain;
 316                 if (unlikely(ed && ed->signal_invmap && sig < 32))
 317                         sig = ed->signal_invmap[sig];
 318         }
 319         regs->rdi = sig;
 320         /* In case the signal handler was declared without prototypes */
 321         regs->rax = 0;
 322
 323         /* This also works for non SA_SIGINFO handlers because they expect the
 324            next argument after the signal number on the stack. */
 325         regs->rsi = (unsigned long)&frame->info;
 326         regs->rdx = (unsigned long)&frame->uc;
 327         regs->rip = (unsigned long) ka->sa.sa_handler;
 328
 329         regs->rsp = (unsigned long)frame;
 330
 331         /* Set up the CS register to run signal handlers in 64-bit mode,
 332            even if the handler happens to be interrupting 32-bit code. */
 333         regs->cs = __USER_CS;
 334
 335         /* This, by contrast, has nothing to do with segment registers -
 336            see include/asm-x86_64/uaccess.h for details. */
 337         set_fs(USER_DS);
 338
 339         regs->eflags &= ~TF_MASK;
 340         if (test_thread_flag(TIF_SINGLESTEP))
 341                 ptrace_notify(SIGTRAP);
 342 #ifdef DEBUG_SIG
 343         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 344                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 345 #endif
 346
 347         return 1;
 348
 349 give_sigsegv:
 350         force_sigsegv(sig, current);
 351         return 0;
 352 }
 353
 354 /*
 355  * OK, we're invoking a handler
 356  */
 357
 358 static int
 359 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 360                 sigset_t *oldset, struct pt_regs *regs)
 361 {
 362         int ret;
 363
 364 #ifdef DEBUG_SIG
 365         printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
 366                 current->pid, sig,
 367                 regs->rip, regs->rsp, regs);
 368 #endif
 369
 370         /* Are we from a system call? */
 371         if ((long)regs->orig_rax >= 0) {
 372                 /* If so, check system call restarting.. */
 373                 switch (regs->rax) {
 374                         case -ERESTART_RESTARTBLOCK:
 375                         case -ERESTARTNOHAND:
 376                                 regs->rax = -EINTR;
 377                                 break;
 378
 379                         case -ERESTARTSYS:
 380                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 381                                         regs->rax = -EINTR;
 382                                         break;
 383                                 }
 384                                 /* fallthrough */
 385                         case -ERESTARTNOINTR:
 386                                 regs->rax = regs->orig_rax;
 387                                 regs->rip -= 2;
 388                                 break;
 389                 }
 390         }
 391
 392         /*
 393          * If TF is set due to a debugger (PT_DTRACE), clear the TF
 394          * flag so that register information in the sigcontext is
 395          * correct.
 396          */
 397         if (unlikely(regs->eflags & TF_MASK)) {
 398                 if (likely(current->ptrace & PT_DTRACE)) {
 399                         current->ptrace &= ~PT_DTRACE;
 400                         regs->eflags &= ~TF_MASK;
 401                 }
 402         }
 403
 404 #ifdef CONFIG_IA32_EMULATION
 405         if (test_thread_flag(TIF_IA32)) {
 406                 if (ka->sa.sa_flags & SA_SIGINFO)
 407                         ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 408                 else
 409                         ret = ia32_setup_frame(sig, ka, oldset, regs);
 410         } else
 411 #endif
 412         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 413
 414         if (ret) {
 415                 spin_lock_irq(&current->sighand->siglock);
 416                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 417                 if (!(ka->sa.sa_flags & SA_NODEFER))
 418                         sigaddset(&current->blocked,sig);
 419                 recalc_sigpending();
 420                 spin_unlock_irq(&current->sighand->siglock);
 421         }
 422
 423         return ret;
 424 }
 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 int do_signal(struct pt_regs *regs, sigset_t *oldset)
 432 {
 433         struct k_sigaction ka;
 434         siginfo_t info;
 435         int signr;
 436
 437         /*
 438          * We want the common case to go fast, which
 439          * is why we may in certain cases get here from
 440          * kernel mode. Just return without doing anything
 441          * if so.
 442          */
 443         if (!user_mode(regs))
 444                 return 1;
 445
 446         if (!oldset)
 447                 oldset = &current->blocked;
 448
 449         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 450         if (signr > 0) {
 451                 /* Reenable any watchpoints before delivering the
 452                  * signal to user space. The processor register will
 453                  * have been cleared if the watchpoint triggered
 454                  * inside the kernel.
 455                  */
 456                 if (current->thread.debugreg7)
 457                         set_debugreg(current->thread.debugreg7, 7);
 458
 459                 /* Whee!  Actually deliver the signal.  */
 460                 return handle_signal(signr, &info, &ka, oldset, regs);
 461         }
 462
 463         /* Did we come from a system call? */
 464         if ((long)regs->orig_rax >= 0) {
 465                 /* Restart the system call - no handlers present */
 466                 long res = regs->rax;
 467                 if (res == -ERESTARTNOHAND ||
 468                     res == -ERESTARTSYS ||
 469                     res == -ERESTARTNOINTR) {
 470                         regs->rax = regs->orig_rax;
 471                         regs->rip -= 2;
 472                 }
 473                 if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
 474                         regs->rax = test_thread_flag(TIF_IA32) ?
 475                                         __NR_ia32_restart_syscall :
 476                                         __NR_restart_syscall;
 477                         regs->rip -= 2;
 478                 }
 479         }
 480         return 0;
 481 }
 482
 483 void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
 484 {
 485 #ifdef DEBUG_SIG
 486         printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
 487                thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
 488 #endif
 489
 490         /* Pending single-step? */
 491         if (thread_info_flags & _TIF_SINGLESTEP) {
 492                 regs->eflags |= TF_MASK;
 493                 clear_thread_flag(TIF_SINGLESTEP);
 494         }
 495
 496         /* deal with pending signal delivery */
 497         if (thread_info_flags & _TIF_SIGPENDING)
 498                 do_signal(regs,oldset);
 499 }
 500
 501 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 502 {
 503         struct task_struct *me = current;
 504         if (exception_trace)
 505                 printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
 506                me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
 507
 508         force_sig(SIGSEGV, me);
 509 }